Bagaimana cara menghitung Flow rate gas bahan bakar

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Saya butuh bantuan untuk menghitung flow rate gas (BBG) u/ bahan bakar turbin gas generator di tempat saya. saya kesulitan untuk menghitung berapa sebenarnya kapasitas maksimum flow rate gas untuk line yg menuju gas station di pabrik. sementra ini saya menggunakan formula Panhandle yg hasilnya dari perhitungan saya ( press > 7 bar) kayanya kurang memuaskan ( diameter pipa gas 6 inch). kira2 bagaimana saya mesti menghitung/menggunakan formula apakah yg semetinya? sebab kami berencana menambah kapasitas dengan menambah line 8 inch.



Tanya – topan kovick


yth rekan milis sekalian,

Saya butuh bantuan untuk menghitung flow rate gas (BBG) u/ bahan bakar turbin gas generator di tempat saya. saya kesulitan untuk menghitung berapa sebenarnya kapasitas maksimum flow rate gas untuk line yg menuju gas station di pabrik. sementra ini saya menggunakan formula Panhandle yg hasilnya dari perhitungan saya ( press > 7 bar) kayanya kurang memuaskan ( diameter pipa gas 6 inch). kira2 bagaimana saya mesti menghitung/menggunakan formula apakah yg semetinya? sebab kami berencana menambah kapasitas dengan menambah line 8 inch.

atas bantuannya saya sampaikan terima kasih..( mohon maaf kalo informasi diatas kurang / tidak jelas u melakukan perhitungan)..


Tanggapan 1 – Nugroho Wibisono


Mas Taufan,

Sepertinya situasi yang mas Taufan tuliskan kok rasa-rasanya kurang lengkap, seperti
1. hasil hitungan gas flowrate dianggap kurang memuaskan itu anda bandingkan dengan data darimana? apa pake rotameter atau ada flowtransmitter atau lainnya?
2. pressure 7 bar itu pressure di upstream atau downstream atau deviasi pressure-nya?

Maaf, saya sendiri hanya mengutip saja dari GPSA di Chapter 17 (dan belum pernah melakukan perhitungan sendiri, paling2 simulasi hysys thok) , bahwa Panhandle A equation lebih merefleksikan aliran gas pada smooth pipes. Dengan mengubah faktor efisiensi E sekitar 0.90, bias mengaproksimasi persamaan flow yang turbulen secara parsial (biasanya asumsinya 0.92). Kalau yang saya baca di bukunya Gas Production Engineering karangan Sanjay Kumar (bukan sutradara dari Bollywood lho!), Panhandle A ini applicable for large diameter pipeline and high flowrates.

Panhandle B yg merupakan revisi, lebih mengaproksimasi menjadi persamaan flow turbulen secara penuh. Kalo katanya pak Kumar, yg ini lebih luas dipakai pada long transmission lines, large diameter line dan pada Reynolds number yg lebih besar.

Yang menarik pada GPSA adalah :
The successful application of these transmission line flow equations in the past has largely involved compensation for discrepancies through the use of adjustment factors, usually termed “efficiencies.” These efficiencies are frequently found in practice by determining the constant required to cause predicted gas equation behavior to agree with flow data. As a result, the values of these factors are specific to particular gas flow equations and field conditions and, under many circumstances, vary with flow rate in a fashion that obscures the real nature of flow behavior in the pipe.

Ya wis, pinter2nya kita ngutak-atik angka2 yg bisa diubah (kalo data pengukuran ya jangan lah). Kalo ga sama lagi hasilnya, ya paling mbalik ngitung lagi hehehe…

Mohon dipersori kalau ngawur dan ngelantur, maklum bukan orang proses… lha wong cuma tukang kok.. hehe


Tanggapan 2 – Djohan.bingito

Bang Topan,
menentukan flow rate BBG untuk gas generator bukan dihitung, tetapi diukur. Perhitungan dengan Panhandle atau yang lain hanya untuk sizing pipanya saja, dengan asumsi P1 dan P2 yang konstan. Dasar sizingnya tentu katalog / info dari pabrik turbine gas generator berapa fuel consumptionnya dan macamana spesifikasinya. Untuk actual consumption ya diukur pakai orifice, turbinemeter, vortexmeter etc. tergantung karakteristik dari gas.


Tanggapan 3 – topan kovick

sebelumnya terima kasih atas responnya,
begini mas wibisono, “kurang memuaskan” itu maksudnya karena saya sendiri masih belum paham jelas apa yg dimaksud upstream pressure maupun downstream pressure..(he3…mohon maaf dalam hal ini, karena saya masih awam urusan seperti ini) permasalahan sebenarnya adalah main line gas yg ada (dari supplier BBG) adalah berukuran 16 inch, sementara yg masuk pabrik kami berukuran 6 inch dan sebelum masuk T/G lewat gas station dulu dan ada reducing valve sehingga max. pressure hanya 16 Kg/cm2. yang ingin saya ketahui adalah maksimum flow rate yang mungkin dari kondisi tsb bagaimana? pressure main line sekitar 22 kg/cm2.
mohon maaf kalo situasinya masi kurang jelas.


Tanggapan 4 – erwan nazam

Dear Pak Topan,

Perhitungan diameter pipa memang didasarkan batasan laju alir yang diperbolehkan. Untuk service gas dengan tekanan 16K , biasanya range laju alir gas yang diperbolehkan adalah 20 – 30 m/sec. Hal ini di dasarkan pada pengalaman empiris untuk menghindari terjadinya noise di pipa yang bisa mengakibatkan erosi.


Tanggapan 5 – Taufiq Firmansyah

Di Associated Press 15 Mei 2005 diberitakan bahwa pemerintah Qatar  tengah gencar2nya membangun fasilitas konversi natural gas ke bahan bakar diesel. Mengingat posisi Indonesia  sebagai pengekspor natural gas no. 1 di dunia tentunya prospeknya akan sangat cerah kalau bisa dikembangkan di sini sehingga  bisa mengurangi polusi akibat kandungan karbon. Di artikel ini dikatakan bahwa prinsip kerjanya menggunakan cobalt. Ada yang bisa memberi pencerahan nggak bagaimana cara kerja proses ini?
Terimakasih atas penjelasannya.

http://www.wired.com/news/technology/0,1282,67534,00.html?tw=wn_tophead_10

  Natural-Gas Diesel May Cut Smog

[Print story] <http://www.wired.com/news/print/0,1294,67534,00.html>
[E-mail story]
<http://www.wired.com/news/story/mail/1,2292,67534,00.html>
<http://avantgo.com/channels/_add_channel.pl?cha_id=6&set_cookie=WN%5F67534%3D67534%3Bpath%3D%2F%3Bdomain%3Dwww%2Ewired%2Ecom%3Bexpires%3DSat%2C+20+Feb+2010+01%3A31%3A52+GMT>
*Page 1* of 1

Associated Press

05:09 PM May. 15, 2005 PT

RAS LAFFAN INDUSTRIAL CITY, Qatar — The rat’s nest of pipes and columns  snaking across the desert harbors a secret process that will use cobalt  to turn natural gas into a powerful, clean-burning diesel fuel. By next  year, rulers of this tiny desert sheikdom hope, these gas-to-liquids, or  GTL, reactors under construction will bring in billions of dollars while  clearing big city smog belched by trucks and buses.

Petroleum experts who have sniffed vials of gin-clear GTL diesel speak  of it with reverence. “It’s a beautiful product,” says Jim Jensen, a  Massachusetts energy economist. “The kerosene smells like perfume.”

In all, some $20 billion has been committed to build an unprecedented  array of clean diesel plants in this Gulf shore industrial park. Those  chipping in include oil titans Royal Dutch/Shell Group, ChevronTexaco  and Exxon Mobil, which is making a $7 billion bet on GTL, the largest  investment in the corporate history of America’s largest company.

Smaller plants in Malaysia, South Africa and the United States have  proved the technology works, but none is nearly as large as those  planned here. In a few years, says Andy Brown, who heads Shell’s office  in Qatar, the country will be “the GTL capital of the world.”

“This really is where GTL will come of age, where the industry will be  born,” he said.

By 2011, the Qatar plants should be producing 300,000 barrels of liquid  fuels and other products daily. The largest GTL plant now producing is  Shell’s plant in Bintulu, Malaysia, churning out 14,700 barrels per day.

The investments amount to a big gamble on a clean alternative to  pollutant-rich crude oil, based on an obscure “synthetic fuel” process  developed to make fuel from coal in 1920s Germany. Like Qatar’s headlong  rush to produce liquefied natural gas, the ruling sheiks here are  pushing GTL as an idea whose time has come.

The clean-burning fuel, with almost none of the smelly sulfur soot  belched by engines firing on conventional diesel, appears tailor-made  for countries looking to reduce emissions in line with the Kyoto  Protocol on global warming.

Faisal al-Suwaidi, chief executive of Qatar Liquefied Gas Co., said  interest has come from Japan, Canada, Korea, Europe and the United  States, the world’s largest polluter. Although Washington has refused to  sign the Kyoto protocols, state and local caps on emissions are pushing  refiners to clean up diesel.

Complying with Kyoto’s strictures “is agenda item No. 1 when we visit  countries like Japan,” al-Suwaidi said over coffee in his office in the  Qatari capital, Doha. “This is the product for them. This is green diesel.”

As far as carbon emissions go, green diesel appears to offer only a  modest dent, partly because natural gas contains less carbon than  oil-based diesel to begin with. The big difference is in sulfur. Sulfur  emissions from diesel engines cause as many as 10,000 deaths a year  among Americans with heart and lung ailments, said William Becker, who  represents state and local air pollution control agencies in the United  States.

“It’s a matter of life and death,” Becker said. “And the solution  depends on removing the sulfur.”

Emissions can be cut further by adding better filters that remove up to  90 percent of remaining particulates, said Richard Kassel, a fuels  expert at the Natural Resources Defense Council in New York.  Sulfur-laden diesel gums up these finer filters, he said.

“Clean fuels open the door to the most advanced emission controls,”  Kassel said.

Tests of GTL fuel are under way in several countries. Shell is already  selling the fuel in Thailand, The Netherlands, Greece and Germany,  charging slightly more than its oil-based diesel. In Europe, Shell calls  the fuel V-Power Diesel.

Environmentalists like Kassel caution that GTL fuel is most attractive  when high oil prices make it competitive. The fuel will probably see  most of its smog-cutting in developing countries where emissions  standards will require better filters.

“It’s going to be a very important blending stock but the idea that it’s  going to compete with crude oil is overstating the case,” Jensen said.  “It sort of cuts down on the use of crude but it’s not going to  massively change things.”

GTL diesel from Sasol Chevron, the South African-American joint venture  that is a 49 percent shareholder in the first Qatari GTL plant, will  surge onto the market next year and could wind up as a niche fuel that  powers fleets of city buses and trucks, company spokesman Malcolm Wells  said.

More likely, says economist Jensen, the clean fuel will be blended with  crude-oil diesel to lower sulfur emissions into compliance with  tightening standards in several countries.

The economics of GTL make sense, experts say, when it’s produced on a  large scale and with a cheap source of natural gas. And Qatar, a  Connecticut-sized thumb on the Arabian peninsula, is perhaps the world’s  best source of cheap gas. It sits on a bubble containing 10 percent of  the world’s known gas reserves, conveniently gathered in the planet’s  largest reservoir.

By 2011, Qatar hopes three ventures will convert natural gas into more  than 300,000 barrels per day of liquids, most of that diesel fuel, but  also including naphtha, liquid petroleum gas and lubricating oil. That  much synthetic diesel won’t cut into the current market for oil-based  diesel — 13 million barrels a day — but it might help clear some  skylines.

The fuel will sell for more than conventional diesel, and is hugely  profitable with current oil prices above $50 a barrel. But Shell will  still profit if oil drops to $20, Brown said. Exxon Mobil aims to  produce 155,000 barrels per day by 2011, said Wayne Harms, Exxon’s chief  in Qatar.

“We have a lot of money invested here. We’re going to invest a lot  more,” Harms said. Exxon counts investments in some 200 countries, and  Qatar “will be one of our top countries by the end of the decade.”

End of story


Tanggapan 6 – Johanes Anton Witono


Pak Taufiq,
Ini merupakan inovasi baru di industri gas yang disebut dengan Gas-To-Liquid(GTL) Technology. Dimana dengan feed berupa gas atau coal dapat menghasilkan product berupa bahan bakar diesel.

Basic prosesnya sederhana, dimana umpan diubah dulu menjadi gas sintetik selanjutnya melewati proses utama di reaktor GTL dan dipisahkan berdasarkan fraksinya untuk menjadi end product. Komponen penting dalam teknologi ini adalah desain reaktor GTL serta pemilihan katalis. Katalis yang digunakan tidak hanya Cobalt tetapi juga dapat menggunakan Iron, tergantung pada komposisi syngas dan end product yang ingin dihasilkan.

Untuk tahapan reaksi kimia atau informasi yang lebih jelas, Pak Taufiq silahkan mencari di website lisensor GTL seperti Syntroleum, Sasol, Shell, ConocoPhillips, dll.


Tanggapan 7 – Achmad Hidayat

Tentang overview natural gas utilization, barangkali artikel berikut bisa jadi awalan, untuk lebih detail-nya bisa difollow link reference-nya.

Note:
Mas Budhi, minta bantuan attachment.


Tanggapan 8 – Oki Muraza


Pak Taufiq Yth,

Prospek GTL memang sedang terang, terutama setelah Shell dan ExxonMobil berlomba-lomba merencanakan GTL (Gas to Liquid) Plant. Seperti kita ketahui, dalam skenario GTL, Natural Gas di convert ke CO & H2 (Syngas) dengan Catalytic Partial Oxidation (CPO), atau Steam Reforming (SR),  atau kombinasi keduanya . Lalu CO & H2 di convert ke bahan bakar cair  dengan Fischer Tropsch (FT) process. Katalis yang banyak digunakan untuk CPO dan SR misalnya Rhodium dan Nickel based catalyst. Yang dimaksud Cobalt based catalyst di artikel Qatar tersebut adalah FT prosesnya. Berikut ada artikel di majalah Chemical and Engineering News tentang GTL, semoga membantu.


http://pubs.acs.org/cen/coverstory/8129/8129catalysis2.html

July 21, 2003 Volume 81, Number 29
CENEAR 81 29 pp. 18-19
ISSN 0009-2347

CATALYZING GTL
Gas-to-liquids fuels are becoming a reality and looming as a robust market for catalysts

ALEXANDER H. TULLO, C&EN NORTHEAST NEWS BUREAU
In early July, a collaboration between Royal Dutch/Shell, DaimlerChrysler, and a local bus company unveiled a bus powered by diesel fuel derived from a gas-to-liquids (GTL) process. The effort is similar to other experiments with alternative fuels. Earlier this year, for example, a road rally of fuel-cell-powered cars was held in California. And fleets of natural-gas-powered vehicles have been on the road for years.

However, major oil companies see nothing “alternative” about GTL fuels. ExxonMobil has invested more than $400 million in its GTL technology. Sasol Chevron, a joint venture between Sasol and ChevronTexaco established to license GTL plants, says natural-gas-based diesel will likely make up 10% of the global diesel market within 15 years.

Bill Bell, vice president of methanol and GTL technology and catalysts at Johnson Matthey, which intends to produce catalysts for the Fischer-Tropsch-based GTL process, shares this optimism. “We are moving from a world which exists on oil refining to one which coexists with gas refining built around GTL facilities,” he says. GTL’s appeal is that it can make use of trapped gas. Countries in the Middle East, for example, have huge reserves of natural gas but little local market for it and no pipeline infrastructure to ship it to larger economies. GTL can convert it into a liquid form that is easier to export. This is the same reason such countries crack ethane to make ethylene and convert that into polyethylene, ethylene glycol, and other petrochemicals. It is also why they convert methane into methanol and liquefied natural gas (LNG).

However, GTL facilities would allow these countries to participate in the much bigger diesel fuel market. Moreover, environmental regulations are calling for the kind of low-sulfur diesel fuels that come out of the GTL process. Of course, GTL technology is by no means a sure thing. It is used extensively by only one company, South Africa’s Sasol, which started making synthetic fuels and chemicals from gasified coal a half century ago because it had no other choice. Embargoes engendered by the country’s apartheid policies forced it to develop fuels from indigenous materials.

GTL processes start with synthesis gas production. The front end of the plant uses a reformer or a gasifier to convert natural gas into carbon monoxide and hydrogen. This technology is similar to processes used for years to make methanol and ammonia. This syngas is then fed into a Fischer-Tropsch reactor, which converts it into a paraffin wax that is hydrocracked to make a variety of products, mostly diesel, but also some naphtha, lube-oil base stocks, and gases. “Fischer-Tropsch is the core of the process and where the novelty resides,” Bell says. And central to the Fischer-Tropsch process is the catalyst. “The whole enabler of a GTL plant is really the F-T catalyst,” says Andrew Stotler, markets director of process technologies at Engelhard. On the other hand, he says, proven catalyst chemistries are used in the front-end syngas making and the back-end hydrocracking steps.

Luc Kersten, Shell’s senior adviser on GTL technologies, agrees: “The catalyst in Fischer-Tropsch is the heart of the plant because that is where all the technology providers do a lot of work trying to distinguish themselves and getting the highest yield.”

Johnson Matthey’s Bell says the catalysts used in the latest generation of Fischer-Tropsch technologies are cobalt-based—usually on alumina supports and often with precious-metal promoters. “Everybody’s got their view of what the formulation should be and is pretty secretive about that formulation.”

Major oil companies see nothing “alternative” about gas-to-liquids fuels.

BUT THE COBALT systems aren’t the only ones used. Older technologies, such as the coal-based process that Sasol employs in South Africa, use iron catalysts. Iron is suited to high-temperature processes that involve a lot of impurities like sulfur in the feedstock, experts say. However, iron produces aromatics, oxides, and other nonparaffins as by-products, while cobalt is very efficient in making paraffins from a relatively clean feedstock. “The attraction of the cobalt catalyst is its high activity and its selectivity to make the molecules we want to make,” says Jeff M. Bigger, chief technology officer at GTL process developer Syntroleum Corp.
However, even Sasol has developed a cobalt catalyst for future Fischer-Tropsch plants. Another licensor, Rentech, offers an iron-based catalyst for a low-temperature process that it claims creates fewer by-products.

But the catalyst isn’t everything, according to Rocco Fiato, intellectual property coordinator of GTL strategic process, but it is not used in a vacuum,” he says, noting that his company–as well as Sasol Chevron and Syntroleum–uses a slurry process in the Fischer-Tropsch step. Shell and BP use a fixed-bed process. In fact, the only commercial, natural-gas-based, low-temperature Fischer-Tropsch GTL plant–Shell’s 12,500-barrel-per-day unit in Bintulu, Malaysia–uses a fixed-bed process. Fixed-bed technology is more proven than slurry, and Kersten says Shell has experience with it and is ready to use it in bigger units. “For us, it is the experience we have had with the Bintulu plant that has given us a lot of confidence in further scaling up that principle,” he says.

And Shell already has plans to scale up the process. The company is pursuing a plant in Qatar that will produce 140,000 bbl per day—a scale that should make the plant competitive in fuels markets. Bintulu, Kersten concedes, is successful mainly because of the unique products it turns out. “Bintulu is competitive in its own right because it produces a large proportion of specialty products,” he says. “That recipe can’t be translated to coming projects because those specialty markets are limited.”

Although Shell stands alone as a commercial operator, Sasol Chevron is the most aggressive GTL developer. The company will begin construction later this year on a 34,000-bbl-per-day plant in Qatar that is a joint venture between Sasol and Qatar Petroleum. Sasol Chevron is also negotiating a joint-venture plant in Nigeria and is studying units in Australia and the Caribbean.

ExxonMobil, which runs multiple pilot plants of hundreds of barrels per day, is also studying a plant in Qatar, as is Syntroleum licensee Marathon. Syntroleum is studying a joint-venture plant in Bolivia. One of the reasons GTL is entering the commercial realm is that the cost of production is coming down. Sasol Chevron says the capital cost of building a 17,000-bbl-per-day plant is about $25,000 per daily bbl of synthetic fuel. The company estimates that fixed and variable costs–including labor, maintenance, and catalysts–are about $5.00 per bbl. Moreover, the company figures that with natural gas prices hypothetically at 50 cents per million Btu–a fraction of the going rate in North America–the cash cost of synthetic fuels production is about $10 per bbl.

Theo H. Fleisch, distinguished adviser of gas technologies for BP America, says BP is experimenting with a 300-bbl-per-day plant in Alaska. He believes that BP’s technology can come in 10 to 20% below the benchmark of $25,000 per daily bbl. “The purpose of our technology development was to have a lower cost technology,” he says.

BETTER CATALYSTS are a big part of the drop in GTL technology costs, Johnson Matthey’s Bell says. “Like most catalysts, if you look at their history you will see a steady optimization, and usually the net result is that the customer gets a more efficient, longer lived catalyst typically without paying what they did to start with.” He notes that reducing precious-metal or cobalt content is one way catalyst companies can reduce costs.

However, Fleisch says economy of scale is a bigger factor in reducing GTL costs. “We believe the best way to bring down cost is by building plants,” he says. “Look at the LNG industry. Over the past 10 to 15 years, the cost has come down 40%, and it didn’t come down because of new technologies, it came down because of economies of scale.”

Shell says the company will build its next GTL plant at less than half the unit cost of the Bintulu facility. ExxonMobil also says it cut costs in half from 10 years ago. “It brings the technology into a realm where it becomes sufficiently interesting that you would look at it as a commercial alternative,” Fiato says. Fleisch says BP’s process can compete with $17-bbl Brent crude oil–less than Brent’s usual price. “Ten years ago, GTL was not economically viable,” he says. “That is why there was no action. It has come to the point where GTL plants can be economical. If you have the right location and the right access to gas, they can be economical, and that is why people are talking about building plants today.” And with GTL ready for ascension, a big market for catalysts is now emerging, Bell says. “We are looking at thousands of tons-plus of catalyst as inventory in a single plant. It is not insubstantial.”

Engelhard’s Stotler notes, sale of catalysts at a GTL plant is more than a one-time proposition. “The newer technologies are going in the direction of slurry reactors, and in that case you are constantly making up catalysts: You lose some every day, and you put some in every day,” he says. Engelhard has a supply agreement for cobalt catalysts with Sasol and Sasol Chevron. In January 2002, it started up a catalyst plant dedicated to GTL in De Meern, the Netherlands. The plant has been running at full capacity, Stotler says, and he thinks that, because Engelhard has aligned with Sasol, an expansion will likely happen in three to five years. “I believe they are ahead of the rest of the industry,” he says. “We wouldn’t be running at 100% of capacity if they weren’t.” Stotler acknowledges that the industry will have many catalyst suppliers. “All of the major catalyst companies are focused on this area, and it is a market that’s coming,” he says. But with the volumes being bandied about in the GTL industry, there may be enough business to go around.


Tanggapan 9 – topan kovick


Sebelumnya terima kasih atas responnya, begini mas wibisono, “kurang memuaskan” itu maksudnya karena saya sendiri masih belum paham jelas apa yg dimaksud upstream pressure maupun  downstream pressure..(he3…mohon maaf dalam hal ini, karena saya masih awam urusan seperti ini) permasalahan sebenarnya adalah main line gas yg  ada (dari supplier BBG) adalah berukuran 16 inch, sementara yg masuk  pabrik kami berukuran 6 inch dan sebelum masuk T/G lewat gas station dulu dan ada reducing valve sehingga max. pressure hanya 16 Kg/cm2. yang ingin saya ketahui adalah maksimum flow rate yang mungkin dari kondisi  tsb bagaimana? pressure main line sekitar 22 kg/cm2. mohon maaf kalo situasinya masi kurang jelas.


Tanggapan 10 – Migas_Indonesia@yahoogroups

Dear Pak Topan,
Perhitungan diameter pipa memang didasarkan batasan laju alir yang  diperbolehkan. Untuk service gas dengan tekanan 16K , biasanya range  laju alir gas yang diperbolehkan adalah 20 – 30 m/sec. Hal ini di dasarkan pada pengalaman empiris untuk menghindari terjadinya noise di pipa yang bisa mengakibatkan erosi.


Tanggapan 11 – topan kovick

Sebelumnya terima kasih atas responnya,  begini mas wibisono, “kurang memuaskan” itu maksudnya karena saya sendiri masih belum paham jelas apa yg dimaksud upstream pressure maupun downstream pressure..(he3…mohon maaf dalam hal ini, karena saya masih  awam urusan seperti ini) permasalahan sebenarnya adalah main line gas yg  ada (dari supplier BBG) adalah berukuran 16 inch, sementara yg masuk  pabrik kami berukuran 6 inch dan sebelum masuk T/G lewat gas station  dulu dan ada reducing valve sehingga max. pressure hanya 16 Kg/cm2. yang ingin saya ketahui adalah maksimum flow rate yang mungkin dari kondisi  tsb bagaimana? pressure main line sekitar 22 kg/cm2.  mohon maaf kalo situasinya masi kurang jelas.


Tanggapan 12 – cahyo@migas-indonesia


Maaf respon-nya telat,

Saya menangkap Mas Tauvan mencoba mencari tahu apa sebenarnya yang menjadi  bottleneck dari system perpipaan fuel gas terpasang. Either itu pipanya  kekecilan atau ada something yang membuatnya jadi bottle neck, seperti ada  control valve atau regulator dan sebagainya.

Melihat adanya perubahan tekanan yang terjadi di perpipaan fuel gas, dari  22 ke 16 kg/cm2 atau dari 230 ke 310 psig, maka kelihatannya Mas Tauvan  harus hati-hati karena jika menggunakan standard ANSI, kemungkinan ada spec  break di perpipaan gas tersebut.Jadi jika nantinya harus mengganti pipa,  anda harus awas

It is OK untuk mengganti regulator atau PCV atau big joe dsb, akan tetapi,  kita harus tahu betul system lain yang terlibat, agar tidak ada yang  terlewat. Contoh misalnya criteria overpressure yang di set di awal design,  PSV capacity vs PCV fail open, dst. Say, itu OK, maka orang control  harusnya mulai nanya tentang seberapa bagusnya cepat tanggap PCV ketika dia  dibesarkan mengingat prosentase “dia” mengambil beban pressure drop  relative akan berkurang. (pernyataan ini perlu dikoreksi jika ternyata laju  aliran fuel gas “yang baru” akan menyebabkan dp across control valve  menjadi naik, etc..bla.bla..)

Lebih dari itu, sebenarnya Mas Tauvan perlu mencari tahu dulu apa yang  diinginkan dan apa yang membatasi masalah ini. Perhitungan bisa menyusul,  rumus bisa dicari di buku atau bertanya di milis.

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