tag:blogger.com,1999:blog-43899540798572301722024-03-19T05:05:05.148-07:00Albanich iuliarsaalbanich iuliarsahttp://www.blogger.com/profile/09435472766893099726noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-4389954079857230172.post-52361434152753496322012-03-17T06:16:00.000-07:002012-03-17T06:16:11.205-07:00<b>CATALYTIC REFORMING PROCESS/<br />
PLATFORMING PROCESS</b><br />
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<b>Pendahuluan </b> <br />
Catalytic reforming (atau UOP menyebut Platforming) telah menjadi bagian penting bagi suatu kilang di seluruh dunia selama bertahun-tahun. Fungsi utama proses catalytic reforming adalah meng-upgrade naphtha yang memiliki octane number rendah menjadi komponen blending mogas (motor gasoline) dengan bantuan katalis melalui serangkaian reaksi kimia. Naphtha yang dijadikan umpan catalytic reforming harus di-treating terlebih dahulu di unit naphtha hydrotreater untuk menghilangkan impurities seperti sulfur, nitrogen, oksigen, halide, dan metal yang merupakan racun berbahaya bagi katalis catalytic reformer yang tersusun dari platina. <br />
Selain itu, catalytic reforming juga memproduksi by-product berupa hydrogen yang sangat bermanfaat bagi unit hydrotreater maupun hydrogen plant atau jika masih berlebih dapat juga digunakan sebagai fuel gas bahan bakar fired heater. Butane, by-product lainnya, sering digunakan untuk mengatur vapor pressure gasoline pool.<br />
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<b>Teori Catalytic Reforming </b> <br />
Feed naphtha ke unit catalytic reforming biasanya mengandung C6 s/d C11, paraffin, naphthene, dan aromatic. Tujuan proses catalytic reforming adalah memproduksi aromatic dari naphthene dan paraffin. <br />
Kemudihan reaksi catalytic reforming sangat ditentukan oleh kandungan paraffin, naphthene, dan aromatic yang terkadung dalam naphtha umpan. Aromatic hydrocarbon yang terkandung dalam naphtha tidak berubah oleh proses catalytic reforming. Sebagian besar napthene bereaksi sangat cepat dan efisien berubah menjadi senyawa aromatic (reaksi ini merupakan reaksi dasar catalytic reforming). Paraffin merupakan senyawa paling susah untuk diubah menjadi aromatic. Untuk aplikasi low severity, hanya sebagian kecil paraffin berubah menjadi aromatic. Sedangkan pada aplikasi high severity, konversi paraffin lebih tinggi, tetapi tetap saja berlangsung lambat dan inefisien.<br />
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<b>Reaksi-reaksi yang Terjadi di Catalytic Reforming </b><br />
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Reaksi-reaksi yang terjadi di catalytic reforming adalah sebagai berikut :<br />
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<b>1. Dehidrogenasi Naphthene </b> <br />
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Naphthene merupakan komponen umpan yang sangat diinginkan karena reaksi dehidrogenasi-nya sangat mudah untuk memproduksi aromatic dan by-product hydrogen. Reaksi ini sangat endotermis (memerlukan panas). Reaksi dehidrogenasi naphthene sangat terbantu oleh metal catalyst function dan temperatur reaksi tinggi serta tekanan rendah.<br />
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<b>2. Isomerisasi Napthene dan Paraffin </b><br />
Isomerisasi cyclopentane menjadi cyclohexane harus terjadi terlebih dahulu sebelum kemudian diubah menjadi aromatic. Reaksi ini sangat tergantung dari kondisi operasi.<br />
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<b>3. Dehydrocyclization Paraffin </b><br />
Dehydrocyclization paraffin merupakan reaksi catalytic reforming yang paling susah. Reaksi dehydrocyclization terjadi pada tekanan rendah dan temperature tinggi. Fungsi metal dan acid dalam katalis diperlukan untuk mendapatkan reaksi ini.<br />
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<b>4. Hydrocracking </b><br />
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Kemungkinan terjadinya reaksi hydrocracking karena reaksi isomerisasi ring dan pembentukan ring yang terjadi pada alkylcyclopentane dan paraffin dank area kandungan acid dalam katalis yang diperlukan untuk reaksi catalytic reforming. <br />
Hydrocracking paraffin relative cepat dan terjadi pada tekanan dan temperature tinggi. Penghilangan paraffin melalui reaksi hydrocracking akan meningkatkan konsentrasi aromatic dalam produk sehingga akan meningkatkan octane number. Reaksi hydrocracking ini tentu mengkonsumsi hydrogen dan menghasilkan yield reformate yang lebih rendah.<br />
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<b>5. Demetalization </b><br />
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Reaksi demetalisasi biasanya hanya dapat terjadi pada severity operasi catalytic reforming yang tinggi. Reaksi ini dapat terjadi selama startup unit catalytic reformate semi-regenerasi pasca regenerasi atau penggantian katalis.<br />
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<b>6. Dealkylation Aromatic </b> <br />
Dealkylation aromatic serupa dengan aromatic demethylation dengan perbedaan pada ukuran fragment yang dihilangkan dari ring. Jika alkyl side chain cukup besar, reaksi ini dapat dianggap sebagai reaksi cracking ion carbonium terhadap rantai samping. Reaksi ini memerlukan temperature dan tekanan tinggi. <br />
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<b>Catalytic Reforming Catalyst Dual Function Balance </b><br />
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Reaksi yang terjadi pada Unit Catalytic Reforming, sebagian reaksi menggunakan fungsi metal dari katalis dan sebagian reaksi lainnya menggunakan fungsi acid dari katalis. Pada unit catalytic cracking sangat penting untuk memiliki balance yang sesuai antara fungsi metal dan fungsi acid dari katalis.<br />
Pada proses catalytic reforming, sangat penting untuk meminimumkan reaksi hydrocracking dan memaksimumkan reaksi dehydrogenation dan dehydrocyclization. Balance ini dijaga dengan pengendalian H2O/Cl yang tepat selama siklus katalis semi-regeneration dan dengan menggunakan teknik regenerasi yang tepat. Fase uap H2O dan HCl berada dalam kesetimbangan dengan permukaan chloride dan kelompok hydroxyl. Terlalu banyak H2O dalam fase uap akan memaksa chloride dari permukaan katalis keluar dan menyebabkan katalis menjadi underchloride (fungsi acid dalam katalis tidak dapat dijalankan dengan baik), sedangkan terlalu banyak chloride dalam fase uap akan menjadikan katalis overchloride yang juga tidak baik untuk katalis (fungsi metal dalam katalis tidak dapat dijalankan dengan baik).<br />
<b><br />
Catalyst Poison </b> <br />
Beberapa racun katalis catalytic reforming adalah sebagai berikut : <br />
<i>• Sulfur</i> <br />
Konsentrasi sulfur maksimum yang diijinkan dalam umpan naphtha adalah 0,5 wt-ppm. Biasanya diusahakan kandungan sulfur dalam umpan naphtha sebesar 0,1-0,2 wt-ppm untuk menjamin stabilitas dan selektivitas katalis yang maksimum. Beberapa sumber yang membuat kandungan sulfur dalam umpan naphta tinggi adalah : proses hydrotreating yang tidak baik (temperature reactor kurang tinggi atau katalis sudah harus diganti), recombination sulfur dari naphtha hydrotreater (dan terbentuknya sedikit olefin) akibat temperature hydrotreater yang tinggi dan tekanan hydrotreater yang rendah, hydrotreater stripper upset, memproses feed yang memiliki end point tinggi. <br />
<i>• Nitrogen </i><br />
Konsentrasi nitrogen maksimum yang diijinkan dalam umpan naphtha adalah 0,5 wt-ppm. Kandungan nitrogen dalam umpan naphtha akan menyebabkan terbentuknya deposit ammonium chloride pada permukaan katalis. Beberapa sumber yang membuat kandungan nitrogen dalam umpan naphtha tinggi adalah : proses hydrotreating yang tidak baik (temperature reactor kurang tinggi atau katalis sudah harus diganti), penggunaan f ilming atau neutralizing amine sebagai corrosion inhibitor di seluruh area yang tidak tepat guna. <br />
<i> • Water </i><br />
Kandungan air dalam recycle gas sebesar 30 mol-ppm sudah menunjukkan excessive water, dissolved oxygen, atau combined oxygen di unit catalytic reforming. Tingkat moisture di atas level ini dapat menyebabkan reaksi hydrocracking yang excessive dan juga dapat menyebabkan coke laydown. Lebih lanjut lagi, kondisi ini akan menyebabkan chloride ter-strip dari katalis, sehingga mengganggu kesetimbangan H2O/Cl dan menyebabkan reaksi menjadi terganggu. <br />
Beberapa sumber yang membuat kandungan air dalam system tinggi adalah : proses hydrotreating yang tidak sesuai, kebocoran heat exchanger yang menggunakan pemanas/pendingin steam/water di upstream unit, system injeksi water catalytic reforming, kebocoran naphtha hydrotreater stripper feed effluent heat exchanger, proses drying yang tidak cukup di drying zone di dalam regeneration tower, dan kebocoran steam jacket di regeneration section. <br />
<i>-Metal </i><br />
Karena efek reaksi irreversible, maka kontaminasi metal ke dalam katalis catalytic reforming sama sekali tidak dibolehkan, sehingga umpan catalytic reformer tidak boleh mengandung metal sedikit pun. Beberapa sumber kandungan metal dalam umpan naphtha adalah : arsenic (ppb) dalam virgin naphtha, lead mungkin timbul akibiat memproses ulang off-spec leaded gasoline atau kontaminasi umpan dari tangki yang sebelumnya digunakan untuk leaded gasoline, produk korosi, senyawa water treating yang mengandung zinc, copper, phosphorous, kandungan silicon dalam cracked naphtha yang berasal dari silicon based antifoam agent yang diijeksikan ke dalam coke chamber untuk mencegah foaming, dan injeksi corrosion inhibitor yang berlebihan ke stripper naphtha hydrotreater. <br />
<i>• High feed end point </i><br />
Catalytic reforming didisain untuk memproduksi aromatic hydrocarbon. Produksi aromatic ini tidak dapat terjadi tanpa kondensasi single ring aromatic menjadi mulgi-ring polycyclic aromatic, yang merupakan petunjuk adanya coke. Endpoint naphtha maksimum yang diijinkan sebagai umpan catalytic reforming adalah 204 oC. Pada endpoint > 204 oC, konsentrasi polycyclic aromatic dalam umpan naphtha akan meningkat tajam. <br />
Jika umpan catalytic reforming merupakan hasil blending dari berbagai sumber (straight run naphtha, hydrocracker naphtha, cracked naphtha), maka tiap arus umpan harus dianalisa secara terpisah dan tiap stream tidak boleh memiliki endpoint > 204 oC. Hasil blending antara high end point stream dengan low end point stream akan ”mengaburkan” kandungan fraksi endpoint yang tinggi.albanich iuliarsahttp://www.blogger.com/profile/09435472766893099726noreply@blogger.com0tag:blogger.com,1999:blog-4389954079857230172.post-71049158723707691102012-02-15T06:32:00.000-08:002012-02-15T06:32:08.797-08:00Naphta Hidrotreating<b>PENDAHULUAN</b><br />
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Naphta adalah fraksi dari hidrokarbon yang diperoleh dari proses pemisahan secara distilasi, yang mempunyai jumlah unsur karbon 6 – 10 (C6-C10) baik itu dalam bentuk parafin, olefin, naften, maupun aromatis. Proses hidrogenasi naphta sangat diperlukan baik di industri refinery maupun di industri petrochemical.<br />
Hydrotreating atau disebut juga hydroprocessing adalah proses hidrogenasi katalitik untuk menjenuhkan hidrokarbon dan menghilangkan sulfur, nitrogen, oksigen, dan logam dari aliran proses. Hydrotreating biasa dilakukan untuk umpan naptha sebelum dialirkan ke unit platforming, karena katalis platforming (platina) sangat sensitif terhadap impurities seperti sulfur, nitrogen,oksigen, dan logam. Hydrotreating biasa juga dilakukan untuk umpan diesel untuk perbaikan kualitas diesel terutama untuk mengurangi kandungan sulfur dalam diesel (spesifikasi produk diesel dari tahun ke tahun semakin ketat terutama dalam hal kandungan sulfur maksimum) dan juga untuk mengurangi kandungan nitrogen dalam diesel yang dapat menyebabkan terjadinya color unstability produk diesel. <br />
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<b>Tujuan proses hydrotreating/hydroprocessing adalah :</b> <br />
1. Memperbaiki kualitas produk akhir (seperti diesel) <br />
2. Pretreating stream (persiapan umpan proses lanjutan) untuk mencegah keracunan katalis di downstream process : <br />
• Catalytic Reforming (Platforming) <br />
• Fluid Catalystic Cracking (FCC) <br />
• Hydrocracking <br />
3. Memenuhi standar lingkungan (untuk diesel sebelum dikirim ke tangki penyimpanan produk) <br />
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Pemilihan tipe katalis bergantung pada aplikasi dan aktivitas / selektivitas yang diinginkan. <br />
• Tipe CoMo : cocok untuk HDS <br />
• Tipe NiMo : cocok untuk HDN, penjenuhan olefin <br />
• Tipe NiW : cocok untuk Hydrocracking, penjenuhan olefin<br />
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<b>METODOLOGI</b><br />
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Teori Hydrotreating <br />
Reaksi hydrotreating dikelompokkan menjadi : <br />
1. Saturasi olefin (penjenuhan hidrokarbon). <br />
2. Desulfurisasi (penghilangan sulfur) atau sering disebut HDS (hydrodesulfurization). <br />
3. Denitrifikasi (penghilangan nitrogen) atau sering disebut (hydrodenitrification). <br />
4. Deoksigenasi (penghilangan oksigen). <br />
5. Demetalisasi (penghilangan logam) atau sering disebut HDM (hydrodemetalization). <br />
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<b><br />
Reaksi yang terjadi di unit Hidrotreating</b><br />
<b><br />
- Reaksi <a href="http://en.wikipedia.org/wiki/Hydrodesulfurization">Hydrodesulfurization</a><br />
<a href="http://en.wikipedia.org/wiki/Hydrodesulfurization"></a> </b><br />
Umumnya reactor inlet temperature 315-340oC akan memberikan kecepatan reaksi hydorgenasi yang cukup dan tidak akan menyebabkan rekombinasi olefin dan hydrogen sulfide (namun tergantung komposisi feed, tekanan operasi, dan LHSV).<br />
Untuk unit naphtha hydrotreater, karena heavy naphtha produk naphtha hydrotreater akan digunakan sebagai umpan unit platforming maka batasan umpan kandungan sulfur dalam produk heavy naphta adalah 0,5 ppm, agar tidak meracuni katalis platforming yang sangat sensitif terhadap impurities. Sedangkan untuk unit distilate (diesel hidrotreater), kandungan sulfur outlet reaktor dapat dijaga sesuai keinginan kita (spesifikasi produk diesel indonesia saat ini masih 500 ppm sulfur, sedangkan spesifikasi diesel yang ada di negara maju sudah ada yang mencapai 30 ppm atau bahka maximum 10 ppm sulfur. Untuk mengatur kandungan sulfur dalam produk dapat dilakukan dengan mengatur temperatur reaktor (naiknya temperatur reaktor akan mengurangi kandungan sulfur dalam produk)<br />
<b><br />
- Reaksi <a href="http://en.wikipedia.org/wiki/Denitrification">Hidrodenitrification</a></b><br />
Biasanya kandungan nitrogen dalam umpan lebih sedikit daripada kandungan sulfur dalam umpan. Namun, reaksi penghilangan nitrogen jauh lebih sulit daripada reaksi penghilangan sulfur, yaitu kurang lebih 5 kali lebih sulit. Untuk unit naphtha hydrotreater, karena heavy naphtha produk naphtha hydrotreater akan digunakan sebagai umpan unit platforming maka batasan maksimum kandungan sulfur dalam produk heavy naphtha adalah 0,5 ppm, agar tidak meracuni katalis platforming yang sangat sensitive terhadap impurities.<br />
Nitrogen yang masuk ke unit platforming akan menyebabkan endapan amonium cloride di circuit recycle gas atau sistem overhead stabilizer. Penghilangan nitogen di unit naphta hidrotreater sangat penting jika naphta hidrotreater mengolah cracked feed.<br />
Sedangkan untuk unit distillate/diesel hydrotreater, walaupun tidak ada batasan maksimum nitrogen dalam produk diesel, namun kandungan nitrogen dalam produk diesel akan mempengaruhi color stability. Semakin rendah kandungan nitrogen, maka semakin tinggi color stability-nya. <br />
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<b>- Reaksi Penghilangan Oksigen <a href="http://en.wikipedia.org/wiki/Deoxygenation">(deoxygenation)</a></b><br />
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<b>- Reaksi <a href="http://en.wikipedia.org/wiki/Hydrodesulfurization#Saturation_of_olefins">penjenuhan Olefin</a> </b><br />
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<b>- Reaksi penghilangan <a href="http://id.wikipedia.org/wiki/Halida">senyawa halida</a></b><br />
Halida organik dapat didekomposisi di unit naphta hidrotreater menjadi hidrogen halida yang kemudian diserap oleh wash water yang diinjeksikan di outlet reaktor atau diambil sebagai stipper gas. Dekomposisi halida organik jauh lebih sulit dari pada desulfurisasi. Biasanya maksimum organic halide removal sekitar 90%, tetapi dapat lebih kecil jika kondisi operasi hanya di-set untuk penghilangan sulfur dan nitrogen saja, untuk alasan ini maka ananlisa periodik terhadap kandungan cloride dalam hidrotreated naphta harus dilakukan, karena tingkat kandungan cloride ini akan digunakan untuk mengatur jumlah injeksi cloride di platformer (cloride di platformer dibutuhkan untuk menjaga suasana asam katalis platformer).<br />
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<b>- Reaksi penghilangan senyawa logam</b><br />
Sebagian besar impurities metal terjadi pada level part per billion (ppb) di dalam naphtha. Biasanya katalis naphtha hydrotreater atau distillate hydrotreater mampu menghilangkan senyawa metal ini pada konsentrasi yang cukup tinggi, yaitu hingga 5 ppmwt atau lebih, dengan basis intermittent pada kondisi normal operasi. Impurities metal ini tetap berada di dalam katalis hydrotreater dan dianggap sebagai racun katalis permanent karena meracuni <br />
katalis secara permanen, tidak dapat dihilangkan dengan cara regenerasi katalis. Beberapa logam yang sering terdeteksi dalam spent catalyst hydrotreater adalah arsenic, iron, calcium, magnesium, phosphorous, lead (timbal), silicon, copper, dan sodium. <br />
Iron biasanya ditemukan terkonsentrasi pada bagian atas catalyst bed sebagai iron sulfide.<br />
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<b>Kinerja Katalis</b> <br />
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Kinerja katalis dapat diketahui atau diukur dengan beberapa parameter sebagai berikut : <br />
• Analisa laboratorium kandungan sulfur, nitrogen, dan olefin (bromine number) pada produk. Jika kandungan sulfur, nitrogen, dan olefin naik pada temperature inlet reactor dan kapasitas serta komposisi feed yang sama, maka berarti kinerja katalis sudah mulai menurun dan untuk menjaga kandungan sulfur, nitrogen, dan olefin yang sama maka temperature inlet reactor harus dinaikkan. <br />
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• ∆T reaktor, yaitu selisih antara temperature bed reaktor tertinggi dengan temperature inlet reaktor. Jika ∆T reaktor menurun pada kapasitas dan komposisi feed yang sama, maka berarti kinerja katalis sudah mulai menurun. <br />
<br />
• ∆P (pressure drop) reaktor, yaitu penurunan tekanan reaktor akibat adanya impurities yang mengendap pada katalis. Biasanya terjadi kalo feed mengandung cracked feed dalam jumlah yang besar atau feed berasal dari tangki penyimpanan yang tidak dilengkapi dengan gas/nitrogen blanketting sehingga feed akan bereaksi dengan oksigen yang akan membentuk gums pada permukaan katalis. <br />
<br />
<br />
<b>Deaktivasi Katalis</b> <br />
Deaktivasi katalis atau penurunan aktivitas katalis dapat disebabkan oleh beberapa faktor yaitu : <br />
- Akumulasi senyawa ammonia pada katalis <br />
Reaksi hydrotreating akan mengubah senyawa nitrogen organic yang ada dalam umpan menjadi ammonia. Jika kandungan ammonia dalam recycle gas tinggi, maka ammonia akan berebut tempat dengan umpan untuk mengisi active site katalis. Jika active site katalis tertutup oleh ammonia maka aktivitas katalis akan langsung menurun. Untuk menghindari terjadinya akumulasi ammonia pada permukaan katalis, diinjeksikan wash water pada effluent reactor, sehingga ammonia akan larut dalam air dan tidak menjadi impurities bagi recycle gas. Ammonia bersifat racun sementara bagi katalis. Jika injeksi wash water dihentikan atau kurang maka akan terjadi akumulasi ammonia pada permukaan katalis, namun setelah injeksi wash water dijalankan kembali maka akumulasi ammonia pada permukaan katalis akan langsung hilang. <br />
- Coke <br />
Coke dapat terjadi karena beberapa hal sebagai berikut : <br />
1. Temperatur reaksi yang tidak sesuai (temperatur terlalu tinggi atau umpan minyak terlalu ringan). <br />
2. Hydrogen partial pressure yang rendah (tekanan reaktor atau hydrogen purity recycle gas yang rendah). <br />
3. Jumlah recycle gas yang kurang (jumlah H2/HC yang kurang/lebih rendah daripada disain). <br />
Pembentukan coke dapat dihambat dengan cara menaikkan hydrogen partial pressure (tekanan reaktor atau hydrogen purity pada recycle gas), atau penggunaan carbon bed absorber untuk menyerap HPNA. <br />
- Keracunan logam <br />
Pada proses penghilangan logam dari umpan, senyawa logam organic terdekomposisi dan menempel pada permukaan katalis. Jenis logam yang biasanya menjadi racun katalis hydrocracker adalah nikel, vanadium, ferro, natrium, kalsium, magnesium, silica, arsenic, timbal, dan phospor. Keracunan katalis oleh logam bersifat permanent dan tidak dapat hilang dengan cara regenerasi. Keracunan logam dapat dicegah dengan membatasi kandungan logam dalam umpan. Best practice batasan maksimum kandungan logam yang terkandung dalam umpan hydrotreater adalah 1,5 ppmwt untuk nikel dan vanadium, 2 ppmwt untuk ferro dan logam lain, serta 0,5 ppmwt untuk natrium. <br />
<br />
<b>Feed dan Produk Hydrotreating </b> <br />
Unit hydrotreating dapat berupa naphtha hydrotreater atau distillate/diesel hydrotreater. Umpan naphtha hydrotreater adalah naphtha yang dapat berupa straight run naphtha, naphtha dari tangki penyimpan, ataupun cracked naphtha. Jika umpan naphtha berasal dari tangki maka harus diyakinkan bahwa tangki dilengkapi dengan gas atau nitrogen blanketing. Jika tangki tidak dilengkapi <br />
dengan gas atau nitrogen blanketing, maka naphtha kemungkinan akan bereaksi dengan oksigen (yang berasal dari udara; biasanya tangki naphtha adalah floating roof yang sangat mungkin terdapat kebocoran seal sehingga dapat menyebabkan udara luar masuk ke dalam tangki) yang kemudian akan menyebabkan terbentuknya gums. Gums ini biasanya terbentuk pada preheater atau bahkan pada permukaan katalis. Sedangkan umpan distillate/diesel hydrotreater adalah straight run diesel atau cracked diesel. Jika mengolah cracked diesel, maka perlu diketahui batasan maksimumnya karena cracked diesel membawa cracked material/olefin yang akan mempengaruhi operasi hydrotreater. Selain itu cracked diesel sangat mungkin mengandung nitrogen yang tinggi. Kandungan nitrogen yang tinggi akan mempengaruhi tingkat color stability produk diesel. <br />
Produk unit hydrotreating dapat berupa hydrotreated heavy naphtha atau hydrotreated diesel. Hydrotreated heavy naphtha merupakan intermediate product yang kemudian merupakan umpan unit platforming. Hydrotreated heavy naphtha harus mempunyai kandungan sulfur dan nitrogen maksimum 0,5 ppmwt dan kandungan logam maksimum 2 ppmwt. Sedangkan hydrotreated diesel merupakan produk jadi siap dipasarkan dengan kandungan sulfur antara 10 ppmwt, 30 ppmwt, atau 500 ppmwt.<br />
<br />
<i>Referensi</i><br />
<br />
Operation Manual for Unit 200 Naphtha Hydrotreating Process Unit, Pakistan-Arabian Refinery Limited, Mid-Country Refinery Project (PARCO), Mahmood Kot, Pakistan.albanich iuliarsahttp://www.blogger.com/profile/09435472766893099726noreply@blogger.com1tag:blogger.com,1999:blog-4389954079857230172.post-53300279782762972522012-02-14T04:08:00.000-08:002012-02-14T04:11:24.974-08:00What's Petrochemical...?<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrek8w9w75_AX17Xh1nAKprkFCeUwwlTifHjFwqT-AofIpoCRvLJ7BojW7So7HdPUD-GBPDTYJxOQnDne1NlysPsBJGfWqD9IkhmR8w5yfnFWtvv4WUXCCsXDCZOvq34Pt8nOp88nAUt8/s1600/300px-TASNEE_001.jpg" imageanchor="1" style="margin-left:1em; margin-right:1em"><img border="0" height="200" width="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrek8w9w75_AX17Xh1nAKprkFCeUwwlTifHjFwqT-AofIpoCRvLJ7BojW7So7HdPUD-GBPDTYJxOQnDne1NlysPsBJGfWqD9IkhmR8w5yfnFWtvv4WUXCCsXDCZOvq34Pt8nOp88nAUt8/s320/300px-TASNEE_001.jpg" /></a></div><br />
<br />
Petrochemicals are chemical products derived from petroleum. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as corn or sugar cane.<br />
<br />
Two petrochemical classes are olefins including ethylene and propylene, and aromatics including benzene, toluene, and xylene isomers. Oil refineries produce olefins and aromatics by fluid catalytic cracking of petroleum fractions. Chemical plants produce olefins by steam cracking of natural gas liquids like ethane and propane. Aromatics are produced by catalytic reforming of naphtha. Olefins and aromatics are the building-blocks for a wide range of materials such as solvents, detergents, and adhesives. Olefins are the basis for polymers and oligomers used in plastics, resins, fibers, elastomers, lubricants, and gels.<br />
<br />
Global ethylene and propylene production are ~110 million tonnes and ~65 million tonnes per annum, respectively. Aromatics production is ~70 million tonnes. The largest petrochemical industries are located in the USA and Western Europe; however, major growth in new production capacity is in the Middle East and Asia. There is substantial inter-regional petrochemical trade.<br />
<br />
<b>Primary petrochemicals are divided into three groups depending on their chemical structure:</b><br />
<br />
* Olefins includes ethylene, propylene, and butadiene. Ethylene and propylene are important sources of industrial chemicals and plastics products. Butadiene is used in making synthetic rubber.<br />
* Aromatics includes benzene, toluene, and xylenes. Benzene is a raw material for dyes and synthetic detergents, and benzene and toluene for isocyanates MDI and TDI used in making polyurethanes. Manufacturers use xylenes to produce plastics and synthetic fibers.<br />
* Synthesis gas is a mixture of carbon monoxide and hydrogen used to make ammonia and methanol. Ammonia is used to make the fertilizer urea and methanol is used as a solvent and chemical intermediate.<br />
<br />
The prefix "petro-" is an arbitrary abbreviation of the word "petroleum"; since "petro-" is Ancient Greek for "rock" and "oleum" means "oil". Therefore, the etymologically correct term would be "oleochemicals". However, the term oleochemical is used to describe chemicals derived from plant and animal fats.<br />
<br />
<br />
<br />
<b>Oil to Petrochemicals</b><br />
<br />
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<br />
Petrochemicals are chemicals made from petroleum (crude oil) and natural gas. Petroleum and natural gas are made up of hydrocarbon molecules, which are comprised of one or more carbon atoms, to which hydrogen atoms are attached.<br />
<br />
Currently, oil and gas are the main sources of the raw materials because they are the least expensive, most readily available, and can be processed most easily into the primary petrochemicals listed on the left.<br />
<br />
Only about five percent of the oil and gas consumed each year is needed to make all the petrochemical products.<br />
Petrochemicals have had a dramatic impact on our food, clothing, shelter and leisure. Some synthetics, tailored for particular uses, actually perform better than products made by nature because of their unique properties.<br />
<b> <br />
Primary Petrochemicals:</b><br />
<br />
"Primary Petrochemicals" include: olefins (ethylene, propylene and butadiene) aromatics (benzene, toluene, and xylenes); and methanol.<br />
<br />
Olefins are unsaturated molecules of carbon (C) and hydrogen (H) that appear as short chains, of two, three or four carbons in length.<br />
Aromatics contain a six carbon ring structure. The oxygen/hydrogen (OH) group in methanol denotes that it is an alcohol. <br />
<br />
<br />
<b>Intermediates and Derivatives:</b><br />
<br />
Petrochemical intermediates are generally produced by chemical conversion of primary petrochemicals to form more complicated derivative products (see graphic on the left).<br />
<br />
Petrochemical derivative products can be made in a variety of ways: directly from primary petrochemicals; through intermediate products which still contain only carbon and hydrogen; and, through intermediates which incorporate chlorine, nitrogen or oxygen in the finished derivative. In some cases, they are finished products; in others, more steps are needed to arrive at the desired composition.<br />
<br />
Of all the processes used, one of the most important is polymerization. It is used in the production of plastics, fibers and synthetic rubber, the main finished petrochemical derivatives.<br />
Some typical petrochemical intermediates are:<br />
vinyl acetate for paint, paper and textile coatings<br />
vinyl chloride for polyvinyl chloride (PVC)<br />
resin manufacture<br />
ethylene glycol for polyester textile fibers<br />
styrene which is important in rubber and plastic manufacturing. <br />
<br />
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<br />
<b>Major End Use Products:</b><br />
<br />
Some typical petrochemical intermediates are:<br />
- vinyl acetate for paint, paper and textile coatings vinyl chloride for<br />
- polyvinyl chloride PVC)<br />
- resin manufacture<br />
- ethylene glycol for polyester - textile fibers<br />
- styrene which is important in rubber and plastic manufacturing.<b></b>albanich iuliarsahttp://www.blogger.com/profile/09435472766893099726noreply@blogger.com0tag:blogger.com,1999:blog-4389954079857230172.post-84804829476939377352012-02-13T15:08:00.000-08:002012-02-13T15:08:05.754-08:00Control Valve<b>What Is A Control Valve?<blockquote></blockquote></b><br />
<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi61Kz_rPiH7I2DW6s_4sO5s1KAmF36Lju9KifHFo1DA_xMhjQQFGO-_W6SVzNaVFysDo5l4UCAP_v87GO0N_-dYWi2yWO-ZlRXg3VmpZvuxaZxByDg0RxuBkGKu-Q_2jrJ3xGCnAHHtD0/s1600/control+valve.jpg" imageanchor="1" style="clear:left; float:left;margin-right:1em; margin-bottom:1em"><img border="0" height="262" width="192" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi61Kz_rPiH7I2DW6s_4sO5s1KAmF36Lju9KifHFo1DA_xMhjQQFGO-_W6SVzNaVFysDo5l4UCAP_v87GO0N_-dYWi2yWO-ZlRXg3VmpZvuxaZxByDg0RxuBkGKu-Q_2jrJ3xGCnAHHtD0/s320/control+valve.jpg" /></a></div><br />
<br />
Process plants consist of hundreds, or even thousands, of control loops all<br />
networked together to produce a product to be offered for sale. Each of these control loops is designed to keep some important process variable such as pressure,flow, level, temperature, etc. within a required operating range to ensure the quality of the end product. Each of these loops receives and internally creates disturbances that detrimentally affect the process variable, and interaction from other loops in the network provides disturbances that influence the process variable.<br />
To reduce the effect of these load disturbances, sensors and transmitters collect information about the process variable and its relationship to some desired setpoint. A controller then processes this information and decides what must be done to get the process variable back to where it should be after a load disturbance occurs. When all the measuring,comparing, and calculating are done,some type of final control element must implement the strategy selected by the controller.<br />
The most common final control element in the process control industries is the control valve. The control valve manipulates a flowing fluid, such as gas, steam,water, or chemical compounds, to compensate for the load disturbance and keep the regulated process variable as close as possible to the desired set point.<br />
Many people who talk about control valves or valves are really referring to a control valve assembly. The control valve assembly typically consists of the valve body, the internal trim parts, an actuator to provide the motive power to operate the valve, and a varietyof additional valve accessories, which can include positioners, transducers,supply pressure regulators, manual operators, snubbers, or limit switches.<br />
<br />
Whether it is called a valve, control valve or a control valve assembly is not as important as recognizing that the control valve is a critical part of the control loop. It is not accurate to say that the control valve is the most important part of the loop. It is useful to think of a control loop as an instrumentation chain. Like any other chain,the whole chain is only as good as its weakest link. It is important to ensurethat the control valve is not the weak est link.<br />
Following are definitions for process control, sliding-stem control valve,rotary-shaft control valve, and other control valve functions and character istics terminology.<br />
<br />
<b><br />
Process Control Terminology</b><br />
<br />
Accessory: A device that is mounted on the actuator to complement the actuator’s function and makeit a complete operating unit. Examples include positioners, supply pressure regulators, solenoids, and limit switches.<br />
<br />
Actuator*: A pneumatic, hydraulic,or electrically powered device that supplies force and motion to open or close a valve.<br />
<br />
Actuator Assembly: An actuator,including all the pertinent accessories that make it a complete operating unit.<br />
<br />
Backlash: The general name given to a form of dead band that results from a temporary discontinuity between the input and output of a device when the input of the device changes direction. Slack, or looseness of a mechanical connection is a typical example.<br />
<br />
Capacity* (Valve): The rate of flow through a valve under stated conditions.<br />
<br />
Closed Loop: The interconnection of process control components such that information regarding the process variable is continuously fed back to the controller set point to provide continuous, automatic corrections to the process variable.<br />
<br />
Controller: A device that operates automatically by use of some established algorithm to regulate a controlled variable. The controller input receives information about the status of the process variable and then provides an appropriate output signal to the final control element.<br />
<br />
Control Range: The range of valve travel over which a control valve can maintain the installed valve gain between the normalized values of 0.5 and 2.0.<br />
<br />
Control Valve Assembly: Includes all components normally mounted on the valve: the valve body assembly, actuator, positioner, air sets, transducers, limit switches, etc.<br />
<br />
Dead Band: The range through which an input signal can be varied,upon reversal of direction, without initiating an observable change in the output signal. Dead band is the name given to a general phenomenon that can apply to any device. For the valve Figure 1-1. Process Dead Band A7152 / IL assembly, the controller output (CO) is the input to the valve assembly and the process variable (PV) is the output as shown in figure 1-1. When the term Dead Band is used, it is essential that both the input and output variables are identified, and that any tests to measure dead band be under fully loaded conditions. Dead band is typically expressed as a percent of the input span.<br />
<br />
Dead Time: The time interval (Td) in which no response of the system is detected following a small (usually 0.25% - 5%) step input. It is measured from the time the step input is initiated to the first detectable response of the system being tested. Dead Time can apply to a valve assembly or to the entire process. <br />
<br />
Disk: A valve trim element used to modulate the flow rate with either linear or rotary motion. Can also be referred to as a valve plug or closure member.<br />
<br />
Gain: An all-purpose term that can be used in many situations. In its most general sense, gain is the ratio of the magnitude of the output change of a given system or device to the magnitude of the input change that caused the output change. Gain has two components: static gain and dynamic gain. <br />
Static gain is the gain relation ship between the input and output and is an indicator of the ease with which the input can initiate a change in the Figure 1-2.<br />
<br />
<br />
Linearity*: The closeness to which a curve relating to two variables approximates a straight line. (Linearity also means that the same straight line will apply for both upscale and downscale directions. Thus, dead band as defined above, would typically be considered a non-linearity.)<br />
<br />
Linear Characteristic*: An inherent flow characteristic that can be repre-sented by a straight line on a rectangular plot of flow coefficient (Cv) versus rated travel. <br />
<br />
Packing: A part of the valve assembly used to seal against leakage around the valve disk or stem.<br />
<br />
Positioner*: A position controller (servomechanism) that is mechanically connected to a moving part of a final control element or its actuator and that automatically adjusts its output to the actuator to maintain a desired position in proportion to the input signal.<br />
Relay: A device that acts as a power amplifier. It takes an electrical, pneumatic, or mechanical input signal and produces an output of a large volume flow of air or hydraulic fluid to the actuator. The relay can be an internal component of the positioner or a separate valve accessory.<br />
<br />
<br />
Trim*: The internal components of a valve that modulate the flow of the controlled fluid.albanich iuliarsahttp://www.blogger.com/profile/09435472766893099726noreply@blogger.com0tag:blogger.com,1999:blog-4389954079857230172.post-9141467683605395772010-12-02T04:28:00.000-08:002010-12-02T04:28:22.515-08:00<span style="color: navy; font-family: Verdana;"> <h3 align="center">Refining</h3></span> <span style="color: black; font-family: Verdana;"> </span><hr /><span style="color: black; font-family: Verdana;"> </span><h3 align="center" style="margin-top: 0pt;"><span style="color: black; font-family: Verdana;"><strong><a href="" name="Topics"> <span style="color: red; font-family: Verdana; font-size: small;">Topics</span></a></strong></span></h3><span style="color: black; font-family: Verdana;"> </span><ol style="font-family: Verdana; font-size: 10pt;"><span style="color: black; font-family: Verdana;">
<li> <h3 align="left"> <span style="font-weight: 400;"><strong style="font-weight: 400;"><a href="http://www.petrostrategies.org/Learning_Center/refining.htm#Refined%20Products%20and%20Qualities"> <span style="font-family: Verdana; font-size: x-small;">Refined Products and Qualities</span></a></strong></span></h3></li>
<li> <h3 align="left"> <span style="font-weight: 400;"><a href="http://www.petrostrategies.org/Learning_Center/refining.htm#Refinery%20Operations"> <span style="font-family: Verdana; font-size: x-small;">Refinery Operations</span></a></span></h3></li>
<li> <h3 align="left"> <span style="font-weight: 400;"><a href="http://www.petrostrategies.org/Learning_Center/refining.htm#Refinery%20Economics"> <span style="font-family: Verdana; font-size: x-small;">Refinery Economics</span></a></span></h3></li>
<li> <div align="left"><span style="font-size: x-small;"> <a href="http://www.petrostrategies.org/Learning_Center/refining.htm#References">References</a></span> </div></li>
</span></ol><span style="color: black; font-family: Verdana;"> </span><hr /> <span style="color: black; font-family: Verdana;"> </span><h3 align="center"><span style="color: black; font-family: Verdana;"><strong><a href="" name="Refined Products and Qualities"> <span style="font-family: Verdana; font-size: small;">Refined Products and Qualities</span></a></strong></span></h3><span style="color: black; font-family: Verdana;"> </span><h3 align="center" style="margin-top: 0pt;"><span style="color: black; font-family: Verdana;"><b> <span style="font-family: Verdana; font-size: small;">Crude Oil Fractions</span></b></span></h3><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">Crude oil is processed or <b> <i><span style="color: red;"> refined</span></i></b> to produce useable products such as gasoline. The process is very complex and involves both chemical reactions and physical separations. Crude oil is composed of thousands of different molecules. It would be nearly impossible to isolate every molecule and make <span style="color: red;"><i><b>finished products</b> </i></span> from each molecule. Chemists and engineers deal with this problem by isolating mixtures of molecules according to the mixture's boiling point range. For example, gasoline molecules might boil in the range from 90 to 400 <sup>o</sup>F. Home heating oil could be from molecular mixes that boil from 500 to 650 <sup>o</sup>F. For convenience, the mixtures or fractions are given a name. The following chart illustrates the boiling range and name of the petroleum <b> <i><span style="color: red;"> fraction</span></i></b>.</span></span></div><span style="color: black; font-family: Verdana;"> </span><div align="center"> <span style="color: black; font-family: Verdana;"> </span><center> <span style="color: black; font-family: Verdana;"> <table border="1" cellspacing="1"><tbody>
<tr> <td align="center" bgcolor="#000000" style="border-style: solid;"> <div align="center"><b><span style="color: white; font-family: Arial; font-size: x-small;"> Fraction</span></b></div></td> <td align="center" bgcolor="#000000" style="border-style: solid;"> <div align="center"><span style="font-family: Arial; font-size: x-small;"><b> <span style="color: white;"> Boiling Range,</span></b><span style="color: white;"> <b> <sup>o</sup>F.</b></span></span></div></td> </tr>
<tr> <td align="left" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">Butanes and lighter</span></td> <td align="center" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;"><90</span></td> </tr>
<tr> <td align="left" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">Light straight run gasoline (LSR) <br />
or light naphtha (LN)</span></td> <td align="center" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">90-190</span></td> </tr>
<tr> <td align="left" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">Naphtha or heavy naphtha (HN) </span></td> <td align="center" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">190-380</span></td> </tr>
<tr> <td align="left" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">Kerosene</span></td> <td align="center" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">380-520</span></td> </tr>
<tr> <td align="left" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">Distillate or atmospheric gas oil (AGO)</span></td> <td align="center" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">520-650</span></td> </tr>
<tr> <td align="left" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">Residua</span></td> <td align="center" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">650 +</span></td> </tr>
<tr> <td align="left" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">Vacuum gas oil (VGO)</span></td> <td align="center" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">650-1000</span></td> </tr>
<tr> <td align="left" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">Vacuum Residua</span></td> <td align="center" style="border-style: solid;"> <span style="font-family: Verdana; font-size: x-small;">1000 +</span></td> </tr>
</tbody></table></span></center> <span style="color: black; font-family: Verdana;"> </span></div><span style="color: black; font-family: Verdana;"> </span><div align="left"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">Refined products are produced by combining fractions from the raw crude oil with those from various refinery processing units. These fractions are mixed or <b> <i><span style="color: red;"> blended</span></i></b> to satisfy specific properties that are important in allowing the refined product to perform as desired in an engine, for ease in handling and to reduce the undesirable emissions produced when the product is burned.</span></span></div><span style="color: black; font-family: Verdana;"> </span><hr /> <span style="color: black; font-family: Verdana;"> </span><h3 align="center"><span style="color: black; font-family: Verdana;"><b> <span style="font-family: Verdana; font-size: small;">Product Specifications</span></b></span></h3><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;"><a href="http://www.petrostrategies.org/images/fillup1.JPG"> <img align="left" alt="Gasoline Fillup" border="0" height="100" src="http://www.petrostrategies.org/Learning_Center/fillup1_small.JPG" width="133" xthumbnail-orig-image="../images/fillup1.JPG" /></a>Most people are familiar with gasoline octane number. It's the number that you refer to when selecting the grade of gasoline to use in your car. The number may be 87 or 89. The vehicle manufacturer recommends a certain type of fuel to be used. In most cars this is 87 octane unleaded gasoline. This octane rating is actually the average of two tests that are run on the finished gasoline - the <span style="color: red; font-family: Verdana; font-size: x-small;"><i> <b> Research Octane</b></i></span> and the <span style="color: red; font-family: Verdana; font-size: x-small;"><i> <b>Motor Octane</b></i></span>. The average is the <span style="color: red;"><b><i>Road Octane </i></b></span> or (R+M)/2 which is posted on the pump. Some of you may remember when gasoline was sold with a Research number. The difference between Research and Motor Octane is around eight with Research being higher.</span></span></div><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">Gasoline is blended to meet the following specifications:</span></span></div><span style="color: black; font-family: Verdana;"> <!--msimagelist--><table border="0" cellpadding="0" cellspacing="0"><!--msimagelist--><tbody>
<tr> <!--msimagelist--><td valign="baseline" width="42"> <img height="7" src="http://www.petrostrategies.org/images/bullet1.gif" width="7" /></td> <td valign="top" width="100%"> <div align="left" style="margin-top: 0pt; word-spacing: 0pt;"><i> <span style="color: red; font-family: Verdana; font-size: x-small;"><b>Reid Vapor Pressure</b></span><span style="font-family: Verdana; font-size: x-small;"> </span> </i> <span style="font-family: Verdana; font-size: x-small;"> (RVP) which is a measure of hydrocarbon vapors and is needed for starting engines. </span> </div><!--msimagelist--></td> </tr>
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<tr> <!--msimagelist--><td valign="baseline" width="42"> <img height="7" src="http://www.petrostrategies.org/images/bullet1.gif" width="7" /></td> <td valign="top" width="100%"> <div align="left" style="margin-top: 0pt; word-spacing: 0pt;"> <span style="font-family: Verdana; font-size: x-small;">Octane which is a measure of <span style="color: red; font-family: Verdana; font-size: x-small;"><i> <b>anti-knock</b></i></span> level of gasoline and is important because knocking lowers engine efficiency and wastes power.</span></div><!--msimagelist--></td> </tr>
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<tr> <!--msimagelist--><td valign="baseline" width="42"> <img height="7" src="http://www.petrostrategies.org/images/bullet1.gif" width="7" /></td> <td valign="top" width="100%"> <div align="left" style="margin-top: 0pt; word-spacing: 0pt;"><i> <span style="color: red; font-family: Verdana; font-size: x-small;"><b>Toxics</b></span><span style="font-family: Verdana; font-size: x-small;"> </span> </i><span style="font-family: Verdana; font-size: x-small;"> which are measures of the harmful components in gasoline and refiners are required to benzene, olefins and sulfur levels.</span></div><!--msimagelist--></td> </tr>
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<tr> <!--msimagelist--><td valign="baseline" width="42"> <img height="7" src="http://www.petrostrategies.org/images/bullet1.gif" width="7" /></td> <td valign="top" width="100%"> <div align="left" style="margin-top: 0pt; word-spacing: 0pt;"> <span style="font-family: Verdana; font-size: x-small;"><i><span style="color: red;"><b>Oxygen content</b></span></i> in reformulated gasolines to reduce the level of green house gas emissions.</span></div><!--msimagelist--></td> </tr>
<!--msimagelist--></tbody></table></span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">Jet fuel is blended to meet the following specifications: </span> <!--msimagelist--><table border="0" cellpadding="0" cellspacing="0"><!--msimagelist--><tbody>
<tr> <!--msimagelist--><td valign="baseline" width="42"> <img height="7" src="http://www.petrostrategies.org/images/bullet1.gif" width="7" /></td> <td valign="top" width="100%"> <div align="left" style="margin-top: 0pt;"><i> <b> <span style="color: red; font-family: Verdana; font-size: x-small;">Freeze Point</span></b><span style="font-family: Verdana; font-size: x-small;"> </span> </i> <span style="font-family: Verdana; font-size: x-small;"> is the temperature at which the fuel forms ice crystals which could clog engine fuel filters. </span> <!--msimagelist--></div></td> </tr>
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<tr> <!--msimagelist--><td valign="baseline" width="42"> <img height="7" src="http://www.petrostrategies.org/images/bullet1.gif" width="7" /></td> <td valign="top" width="100%"> <div align="left" style="margin-top: 0pt;"><i> <span style="color: red; font-family: Verdana; font-size: x-small;"><b>Viscosity</b></span><span style="font-family: Verdana; font-size: x-small;"> </span> </i><span style="font-family: Verdana; font-size: x-small;"> is a measure of how easily the jet fuel flows.</span><!--msimagelist--></div></td> </tr>
<!--msimagelist--></tbody></table></span></div><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">Diesel engines are different than gasoline engines, and, as result, have different specifications: </span> <!--msimagelist--><table border="0" cellpadding="0" cellspacing="0"><!--msimagelist--><tbody>
<tr> <!--msimagelist--><td valign="baseline" width="42"> <img height="7" src="http://www.petrostrategies.org/images/bullet1.gif" width="7" /></td> <td valign="top" width="100%"> <div style="margin-top: 0pt; text-align: left;"><i> <b> <span style="color: red; font-family: Verdana; font-size: x-small;">Cetane Index</span></b><span style="font-family: Verdana; font-size: x-small;"> </span> </i> <span style="font-family: Verdana; font-size: x-small;"> is a measure of engine performance. </span> <!--msimagelist--></div></td> </tr>
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<tr> <!--msimagelist--><td valign="baseline" width="42"> <img height="7" src="http://www.petrostrategies.org/images/bullet1.gif" width="7" /></td> <td valign="top" width="100%"> <div style="margin-top: 0pt; text-align: left;"><i> <b> <span style="color: red; font-family: Verdana; font-size: x-small;">Sulfur</span></b><span style="font-family: Verdana; font-size: x-small;"> </span> </i><span style="font-family: Verdana; font-size: x-small;"> content determines the level of sulfur oxides in the exhaust. </span> <!--msimagelist--></div></td> </tr>
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<tr> <!--msimagelist--><td valign="baseline" width="42"> <img height="7" src="http://www.petrostrategies.org/images/bullet1.gif" width="7" /></td> <td valign="top" width="100%"> <div style="margin-top: 0pt; text-align: left;"><i> <span style="color: red; font-family: Verdana; font-size: x-small;"><b>Pour Point</b> </span> </i> <span style="font-family: Verdana; font-size: x-small;">is the temperature at which the diesel fuel flows. </span><!--msimagelist--></div></td> </tr>
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<tr> <!--msimagelist--><td valign="baseline" width="42"> <img height="7" src="http://www.petrostrategies.org/images/bullet1.gif" width="7" /></td> <td valign="top" width="100%"> <div style="margin-top: 0pt; text-align: left;"><i> <b> <span style="color: red; font-family: Verdana; font-size: x-small;">Viscosity</span></b><span style="font-family: Verdana; font-size: x-small;"> </span> </i><span style="font-family: Verdana; font-size: x-small;"> is a measure of how easily the diesel fuel flows. </span> <!--msimagelist--></div></td> </tr>
<!--msimagelist--></tbody></table></span></div><div align="left"> <span style="color: black; font-family: Verdana;"> <span style="color: black; font-family: Arial; font-size: xx-small;"> <img border="0" height="15" src="http://www.petrostrategies.org/arrow.jpg" width="6" /> </span> <span style="font-family: Arial; font-size: xx-small;">Go to the<b> </b> </span> <a href="http://www.petrostrategies.org/Learning_Center/refining.htm#Topics"><span style="font-family: Arial; font-size: xx-small;"> Topic Listing</span></a><b><span style="font-family: Arial; font-size: x-small;"> </span></b></span></div><span style="color: black; font-family: Verdana;"> </span><hr /> <span style="color: black; font-family: Verdana;"> </span><h3 align="center"><span style="color: black; font-family: Verdana;"><b><a href="" name="Refinery Operations"> <span style="font-family: Verdana; font-size: small;">Refinery Operations</span></a></b></span></h3><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;"><a href="http://www.petrostrategies.org/images/refine01.JPG"> <img align="right" alt="Refinery" border="0" height="100" src="http://www.petrostrategies.org/Learning_Center/refine01_small.JPG" width="133" xthumbnail-orig-image="../images/refine01.JPG" /></a>Refineries are composed of many different operating units that are used to separate fractions, improve the quality of the fractions and increase the production of higher-valued products like gasoline, jet fuel, diesel oil and home heating oil. The basic refining operations are described in the following sections.</span></span></div><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> </span></div><span style="color: black; font-family: Verdana;"> </span><hr /> <h3 align="center"><span style="color: black; font-family: Verdana;"><b> <span style="font-family: Verdana; font-size: small;">Crude Oil Distillation</span></b></span></h3><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"><span style="color: black; font-family: Verdana;"><b><i> <span style="color: red; font-family: Verdana; font-size: x-small;">Crude oil distillation</span></i></b><span style="font-family: Verdana; font-size: x-small;"> is used to separate the hydrocarbons in crude oil into fractions based on their boiling points. The separation is done in a large tower that is operated at atmospheric pressure. The tower contains a number of trays where hydrocarbon gases and liquids interact. The liquids flow down the tower and the gases up. The lighter materials such as butane and naphtha are removed in the upper section of the tower and the heavier materials such as distillate and residual fuel oil are withdrawn from the lower section. </span></span></div><h3 style="margin-top: 0pt;"><span style="color: black; font-family: Verdana;"><b> <span style="font-family: Verdana; font-size: small;">Vacuum Distillation</span></b></span></h3><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">The residua fraction (650 <sup>o</sup>F. and higher boiling material) from the crude tower can be sent to fuel blending to produce residual fuel oil or No. 6 fuel oil. Often this residua fraction is further separated into a <i> <span style="color: red; font-family: Verdana; font-size: x-small;"><b>vacuum gas oil</b></span></i> and <span style="color: red; font-family: Verdana; font-size: x-small;"><i><b>vacuum residua</b></i></span>. This unit is operated at a slight vacuum. This allows the hydrocarbons to be separated at lower temperatures and prevent undesirable chemical reactions that would "burn" the material and produce <i> <span style="color: red; font-family: Verdana; font-size: x-small;"><b>petroleum coke</b></span></i>. The vacuum gas oil is sent to the catalytic cracking unit for further processing. The vacuum residua is sent to a coking unit for further processing or to fuel oil blending. </span></span></div><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-size: x-small;"> <a href="http://www.petrostrategies.org/images/Primary%20Distillation%20Flow%20Chart.jpg" style="text-decoration: none;" title="Primary Distillation Flow Chart"> <img align="right" alt="Primary Distillation Flow Chart" border="0" height="100" src="http://www.petrostrategies.org/images/Primary%20Distillation%20Flow%20Chart_small.jpg" width="136" xthumbnail-orig-image="../images/Primary Distillation Flow Chart.jpg" /></a></span><span style="font-family: Verdana; font-size: x-small;">The fractions from the crude and vacuum distillation units are then sent to fuel blending or other <i><b> <span style="color: red;"> d</span></b></i></span><i><span style="color: red; font-family: Verdana; font-size: x-small;"><b>ownstr</b></span><b><span style="color: red; font-family: Verdana; font-size: x-small;">eam</span></b></i><span style="font-family: Verdana; font-size: x-small;"> processing units as shown in the following chart. The chart or </span> </span> <span style="font-family: Verdana; font-size: x-small;"> <span style="color: red; font-family: Verdana;"> <i><b>flowsheet</b></i></span><span style="color: black; font-family: Verdana;"> represents the simplest type of refinery which distills the crude oil into its natural components. </span> </span> <span style="color: black; font-family: Verdana;"> <span style="font-size: x-small;">Additional refining processes are used to increase the production of higher-valued products such as gasoline and diesel fuel and improve the quality of of the finished products.</span></span></div><span style="color: black; font-family: Verdana;"> </span><hr /> <h3 align="center"><span style="color: black; font-family: Verdana;"><b> <span style="font-family: Verdana; font-size: small;">Catalytic Reforming</span></b></span></h3><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">Catalytic reforming is used to improve the quality of naphtha from the crude distillation unit. The catalytic reforming unit uses a <span style="color: red;"><i><b>catalyst</b> </i></span> to allow the chemical reactions to take place under "reasonable" temperatures and pressure and "encourage" the desired hydrocarbons to be produced. The motivation for using catalytic reforming can be seen in the following table:</span></span></div><span style="color: black; font-family: Verdana;"> </span><div align="center"> <span style="color: black; font-family: Verdana;"> </span><center> <span style="color: black; font-family: Verdana;"> <table border="1" cellspacing="1" id="AutoNumber23" style="width: 629px;"><tbody>
<tr> <td align="center" bgcolor="#000000" width="219"> <div align="left" style="margin-top: 0pt;"><b> <span style="color: white; font-family: Verdana; font-size: x-small;">Hydrocarbon</span></b></div></td> <td align="center" bgcolor="#000000" width="78"> <div align="left" style="margin-top: 0pt;"><b> <span style="color: white; font-family: Verdana; font-size: x-small;">Hexane</span></b></div></td> <td align="center" bgcolor="#000000" width="79"> <div align="left" style="margin-top: 0pt;"><b> <span style="color: white; font-family: Verdana; font-size: x-small;">Hexene</span></b></div></td> <td align="center" bgcolor="#000000" width="132"> <div align="left" style="margin-top: 0pt;"><b> <span style="color: white; font-family: Verdana; font-size: x-small;">Cyclohexane</span></b></div></td> <td align="center" bgcolor="#000000" width="93"> <div align="left" style="margin-top: 0pt;"><b> <span style="color: white; font-family: Verdana; font-size: x-small;">Benzene</span></b></div></td> </tr>
<tr> <td width="219"> <div align="left" style="margin-top: 0pt;"><span style="font-family: Verdana; font-size: x-small;"> Hydrocarbon Type</span></div></td> <td align="center" width="78"> <div align="left" style="margin-top: 0pt;"><span style="font-family: Verdana; font-size: x-small;"> Paraffin</span></div></td> <td align="center" width="79"> <div align="left" style="margin-top: 0pt;"><span style="font-family: Verdana; font-size: x-small;"> Olefin</span></div></td> <td align="center" width="132"> <div align="left" style="margin-top: 0pt;"><span style="font-family: Verdana; font-size: x-small;"> Naphthene </span></div></td> <td align="center" width="93"> <div align="left" style="margin-top: 0pt;"><span style="font-family: Verdana; font-size: x-small;"> Aromatic</span></div></td> </tr>
<tr> <td width="219"> <div align="left" style="margin-top: 0pt;"><span style="font-family: Verdana; font-size: x-small;"> Research Octane Number</span></div></td> <td align="center" width="78"> <div align="left" style="margin-top: 0pt;"><span style="font-family: Verdana; font-size: x-small;"> 25</span></div></td> <td align="center" width="79"> <div align="left" style="margin-top: 0pt;"><span style="font-family: Verdana; font-size: x-small;"> 80</span></div></td> <td align="center" width="132"> <div align="left" style="margin-top: 0pt;"><span style="font-family: Verdana; font-size: x-small;"> 83</span></div></td> <td align="center" width="93"> <div align="left" style="margin-top: 0pt;"><span style="font-family: Verdana; font-size: x-small;"> 106</span></div></td> </tr>
</tbody></table></span></center> <span style="color: black; font-family: Verdana;"> </span></div><span style="color: black; font-family: Verdana;"> </span><div align="left"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">Therefore this process provides higher octane material to the gasoline pool to help meet the octane specifications on the gasoline. The process also produces hydrogen which is used to remove sulfur from refinery streams in the hydrotreating processes. </span></span></div><span style="color: black; font-family: Verdana;"> </span><hr /> <h3 align="center"><span style="color: black; font-family: Verdana;"><b> <span style="font-family: Verdana; font-size: small;">Catalytic Cracking</span></b><span style="font-family: Verdana; font-size: small;"><a href="http://www.petrostrategies.org/images/catcrak.jpg" style="text-decoration: none;" title="Catalytic Cracking Unit"><span style="color: black;"><img align="right" alt="Catalytic Cracking Unit" border="0" height="162" src="http://www.petrostrategies.org/images/catcrak_small.jpg" width="100" xthumbnail-orig-image="../images/catcrak.jpg" /></span></a></span></span></h3><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">Catalytic cracking is a very important process in the modern refinery. The process allows the refiner to convert material that would normally be burned as fuel (vacuum gas oil) into gasoline and distillate (home heating oil and diesel fuel). One only need examine the price difference between residual fuel oil and gasoline to see why this is an attractive alternative. (For current prices see <a href="http://www.petrostrategies.org/Graphs/gc_spot_product_prices.htm">Gulf Coast Spot Product Prices</a>). </span></span></div><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">This process breaks or <b> <i> <span style="color: red;"> cracks</span></i></b> long chain hydrocarbons into smaller molecules in the naphtha and distillate boiling range to increase gasoline and diesel production. This process will yield 50-60% gasoline, 20-30% distillate and 30% butanes and lighter. If you do the math you will see that the volume of products is greater than the volume of the feed. This is because the long chain hydrocarbons are broken into smaller ones. </span></span></div><span style="color: black; font-family: Verdana;"> </span><hr /> <span style="color: black; font-family: Verdana;"> </span><h3 align="center"><span style="color: black; font-family: Verdana;"><b> <span style="font-family: Verdana; font-size: small;">Alkylation and Isomerization</span></b></span></h3><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">In the <i><span style="color: red;"><b> alkylation</b> </span></i>process, isobutane is reacted with either isobutylene or propylene to form complex paraffin <span style="color: red; font-family: Verdana; font-size: x-small;"><i><b>isomers</b></i></span>. the reactions take place in the presence of hydrofluoric or sulfuric acid catalysts. By combing these molecules the octane level of the paraffin isomer or alkylate is increased to around 93-96 octane. Refiners use this process to improve the octane level of the gasoline pool.</span></span></div><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">Light naphtha (90-190 <sup>o</sup>F.) can have its octane number improved by the use of an <span style="color: red; font-family: Verdana; font-size: x-small;"><i><b>isomerization</b></i></span> process to convert normal paraffins into their isomers. This results in an increase in octane number as evidenced by increase in normal pentane (62 octane) to iso-pentane (92 octane). The process uses a platinum catalyst. Like alkylation, this process improves the octane quality of the gasoline pool.</span></span></div><span style="color: black; font-family: Verdana;"> </span><hr /> <span style="color: black; font-family: Verdana;"> </span><h3 align="center"><span style="color: black; font-family: Verdana;"><b> <span style="font-family: Verdana; font-size: small;">Hydrotreating</span></b></span></h3><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"><span style="color: black; font-family: Verdana;"><i> <b> <span style="color: red; font-family: Verdana; font-size: x-small;">Hydrotreating</span></b><span style="font-family: Verdana; font-size: x-small;"> </span> </i><span style="font-family: Verdana; font-size: x-small;"> is a process where a petroleum fraction is reacted with hydrogen for the purpose of removing impurities. The process is usually used to remove sulfur. Hydrotreating processes use hydrogen from the catalytic reformer or a hydrogen plant. </span></span></div><span style="color: black; font-family: Verdana;"> </span><hr /> <span style="color: black; font-family: Verdana;"> </span><h3 align="center"><span style="color: black; font-family: Verdana;"><b> <span style="font-family: Verdana; font-size: small;">Product Blending</span></b></span></h3><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"><span style="font-family: Verdana; font-size: x-small;">Product <i><b><span style="color: red;">blending</span></b></i> is where the different petroleum fractions are combined together to make the final product. The fractions are mixed so they meet the specifications discussed earlier. Each product has a specific recipe that calls for the proper mix of petroleum fractions. For example, in order to make gasoline, the refiner would mix naphtha, reformate, catalytic gasoline, alkylate and butane so that the mixture had the required octane number, vapor pressure, sulfur level and aromatics content. The process requires knowing these values for all of the components going into the blend. The recipes are developed using computer models.</span></span></div><span style="color: black; font-family: Verdana;"> </span><hr /> <span style="color: black; font-family: Verdana;"> </span><h3 align="center"><span style="color: black; font-family: Verdana;"><b> <span style="font-family: Verdana; font-size: small;">Refinery Complexity</span></b></span></h3><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;"><a href="http://www.petrostrategies.org/images/refnite.JPG"> <img align="left" alt="Refinery at Night" border="0" height="100" src="http://www.petrostrategies.org/Learning_Center/refnite_small.JPG" width="133" xthumbnail-orig-image="../images/refnite.JPG" /></a>Not all refineries are the same. Refineries can range in size from small units capable of processing 10,000 B/D of crude oil to giant complexes running on 700,000 B/D of crude oil. The United States has 150 refineries with a combined capacity of 17.6 barrels per day of refinery capacity. In 2008 the average refinery utilization was 85.4%. Nearly 48% is located in US PADD III which includes Texas, Louisiana, Arkansas and New Mexico.</span></span></div><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> </span></div><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-size: x-small;"> <a href="http://www.petrostrategies.org/images/Refinery%20Flowchart.jpg" style="text-decoration: none;"> <img align="right" alt="Complex Refinery Flowchart" border="0" height="100" src="http://www.petrostrategies.org/images/Refinery%20Flowchart_small.jpg" width="128" xthumbnail-orig-image="../images/Refinery Flowchart.jpg" /></a></span><span style="font-family: Verdana; font-size: x-small;">Refineries can range from simple topping plants with only a crude oil distillation tower to the more complex refinery shown in the flowsheet. This refinery includes reforming (REF), catalytic cracking (FCC) and coking (COK). Sulfur is removed using the hydrotreating (HYT) and hydrodesulfurization (HR) processes.</span></span></div><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> </span></div><span style="color: black; font-family: Verdana;"> </span><div align="left" style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;">Refinery product yields vary from different parts of the country as seen in the following chart: </span></span></div><span style="color: black; font-family: Verdana;"> </span><div style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: x-small;"><b>U.S. Refinery Yields , Percentage of Crude Oil Charge</b></span></span></div><span style="color: black; font-family: Verdana;"> <table border="1" cellspacing="1" height="242" style="width: 804px;"><tbody>
<tr> <td align="center" bgcolor="#000000" height="60" valign="bottom" width="162"><b> <span style="color: white; font-family: Verdana; font-size: x-small;">Product</span></b></td> <td align="center" bgcolor="#000000" height="60" valign="bottom" width="65"><b> <span style="color: white; font-family: Verdana; font-size: x-small;">PADD I<br />
East <br />
Coast</span></b></td> <td align="center" bgcolor="#000000" height="60" valign="bottom" width="86"><b> <span style="color: white; font-family: Verdana; font-size: x-small;">PADD II <br />
Midwest</span></b></td> <td align="center" bgcolor="#000000" height="60" valign="bottom" width="118"><b> <span style="color: white; font-family: Verdana; font-size: x-small;">PADD III<br />
Southwest </span></b></td> <td align="center" bgcolor="#000000" height="60" valign="bottom" width="168"><b> <span style="color: white; font-family: Verdana; font-size: x-small;">PADD IV<br />
Rocky Mountains</span></b></td> <td align="center" bgcolor="#000000" height="60" valign="bottom" width="110"> <span style="color: black; font-family: Verdana;"> <b> <span style="color: white; font-family: Verdana; font-size: x-small;">PADD V <br />
West Coast</span></b></span></td> <td align="center" bgcolor="#000000" height="60" valign="bottom" width="58"> <b><span style="color: white; font-size: x-small;">Total</span></b></td> </tr>
<tr> <td align="left" height="25" valign="bottom" width="162"><span style="font-family: Verdana; font-size: x-small;"> LPGs</span></td> <td align="right" height="25" width="65"><span style="font-size: x-small;">3.2</span></td> <td align="right" height="25" width="86"><span style="font-size: x-small;">3.5</span></td> <td align="right" height="25" width="118"><span style="font-size: x-small;">5.1</span></td> <td align="right" height="25" width="168"><span style="font-size: x-small;">1.6</span></td> <td align="right" height="25" width="110"><span style="font-size: x-small;">2.8</span></td> <td align="right" height="25" width="58"><span style="font-size: x-small;">4.1</span></td> </tr>
<tr> <td align="left" height="20" valign="bottom" width="162"><span style="font-family: Verdana; font-size: x-small;"> Gasoline</span></td> <td align="right" height="20" width="65"><span style="font-size: x-small;">44.6</span></td> <td align="right" height="20" width="86"><span style="font-size: x-small;">48.4</span></td> <td align="right" height="20" width="118"><span style="font-size: x-small;">41.6</span></td> <td align="right" height="20" width="168"><span style="font-size: x-small;">47.3</span></td> <td align="right" height="20" width="110"><span style="font-size: x-small;">45.2</span></td> <td align="right" height="20" width="58"><span style="font-size: x-small;">44.2</span></td> </tr>
<tr> <td align="left" height="20" valign="bottom" width="162"><span style="font-family: Verdana; font-size: x-small;"> Jet Fuel</span></td> <td align="right" height="20" width="65"><span style="font-size: x-small;">5.7</span></td> <td align="right" height="20" width="86"><span style="font-size: x-small;">6.3</span></td> <td align="right" height="20" width="118"><span style="font-size: x-small;">9.4</span></td> <td align="right" height="20" width="168"><span style="font-size: x-small;">4.8</span></td> <td align="right" height="20" width="110"><span style="font-size: x-small;">17.5</span></td> <td align="right" height="20" width="58"><span style="font-size: x-small;">9.6</span></td> </tr>
<tr> <td align="left" height="20" valign="bottom" width="162"><span style="font-family: Verdana; font-size: x-small;"> Distillate Fuel Oil</span></td> <td align="right" height="20" width="65"><span style="font-size: x-small;">29.5</span></td> <td align="right" height="20" width="86"><span style="font-size: x-small;">30.0</span></td> <td align="right" height="20" width="118"><span style="font-size: x-small;">28.3</span></td> <td align="right" height="20" width="168"><span style="font-size: x-small;">31.6</span></td> <td align="right" height="20" width="110"><span style="font-size: x-small;">21.6</span></td> <td align="right" height="20" width="58"><span style="font-size: x-small;">27.8</span></td> </tr>
<tr> <td align="left" height="20" valign="bottom" width="162"><span style="font-family: Verdana; font-size: x-small;"> Residual Fuel Oil</span></td> <td align="right" height="20" width="65"><span style="font-size: x-small;">7.1</span></td> <td align="right" height="20" width="86"><span style="font-size: x-small;">1.6</span></td> <td align="right" height="20" width="118"><span style="font-size: x-small;">4.0</span></td> <td align="right" height="20" width="168"><span style="font-size: x-small;">2.2</span></td> <td align="right" height="20" width="110"><span style="font-size: x-small;">5.5</span></td> <td align="right" height="20" width="58"><span style="font-size: x-small;">4.0</span></td> </tr>
<tr> <td align="left" height="17" valign="bottom" width="162"> <span style="font-size: x-small;">Petroleum Coke</span></td> <td align="right" height="17" width="65"><span style="font-size: x-small;">3.3</span></td> <td align="right" height="17" width="86"><span style="font-size: x-small;">4.3</span></td> <td align="right" height="17" width="118"><span style="font-size: x-small;">5.9</span></td> <td align="right" height="17" width="168"><span style="font-size: x-small;">4.6</span></td> <td align="right" height="17" width="110"><span style="font-size: x-small;">6.0</span></td> <td align="right" height="17" width="58"><span style="font-size: x-small;">5.3</span></td> </tr>
<tr> <td align="left" height="17" valign="bottom" width="162"> <span style="font-size: x-small;">Asphalt & Road Oil</span></td> <td align="right" height="17" width="65"><span style="font-size: x-small;">5.1</span></td> <td align="right" height="17" width="86"><span style="font-size: x-small;">5.3</span></td> <td align="right" height="17" width="118"><span style="font-size: x-small;">1.2</span></td> <td align="right" height="17" width="168"><span style="font-size: x-small;">6.1</span></td> <td align="right" height="17" width="110"><span style="font-size: x-small;">1.4</span></td> <td align="right" height="17" width="58"><span style="font-size: x-small;">2.7</span></td> </tr>
<tr> <td align="left" height="17" valign="bottom" width="162"> <span style="font-size: x-small;">Petrochemical Feedstock</span></td> <td align="right" height="17" width="65"><span style="font-size: x-small;">1.1</span></td> <td align="right" height="17" width="86"><span style="font-size: x-small;">1.0</span></td> <td align="right" height="17" width="118"><span style="font-size: x-small;">3.7</span></td> <td align="right" height="17" width="168"><span style="font-size: x-small;">0.0</span></td> <td align="right" height="17" width="110"><span style="font-size: x-small;">0.1</span></td> <td align="right" height="17" width="58"><span style="font-size: x-small;">2.2</span></td> </tr>
<tr> <td align="left" height="17" valign="bottom" width="162"><span style="font-family: Verdana; font-size: x-small;"> Other </span></td> <td align="right" height="17" width="65"><span style="font-size: x-small;">5.8</span></td> <td align="right" height="17" width="86"><span style="font-size: x-small;">5.1</span></td> <td align="right" height="17" width="118"><span style="font-size: x-small;">7.7</span></td> <td align="right" height="17" width="168"><span style="font-size: x-small;">5.7</span></td> <td align="right" height="17" width="110"><span style="font-size: x-small;">6.5</span></td> <td align="right" height="17" width="58"><span style="font-size: x-small;">6.4</span></td> </tr>
<tr> <td align="left" height="20" valign="bottom" width="162"><span style="font-family: Verdana; font-size: x-small;"> Total</span></td> <td align="right" height="20" width="65"><span style="font-size: x-small;">105.4</span></td> <td align="right" height="20" width="86"><span style="font-size: x-small;">105.5</span></td> <td align="right" height="20" width="118"><span style="font-size: x-small;">106.9</span></td> <td align="right" height="20" width="168"><span style="font-size: x-small;">103.9</span></td> <td align="right" height="20" width="110"><span style="font-size: x-small;">106.6</span></td> <td align="right" height="20" width="58"><span style="font-size: x-small;">106.3</span></td> </tr>
</tbody></table></span><div style="margin-top: 0pt;"> <span style="color: black; font-family: Verdana;"> <span style="font-family: Verdana; font-size: xx-small;">[Source: EIA, <a href="http://tonto.eia.doe.gov/dnav/pet/pet_pnp_pct_dc_nus_pct_a.htm"> Refinery Yield</a>, 2008.]</span></span></div>albanich iuliarsahttp://www.blogger.com/profile/09435472766893099726noreply@blogger.com0