Ethylene cracker operations

Consumers can also negotiate with feedstock suppliers on upfront payments or payment terms under which they pay a higher price than the lowest market price at the trough, but pay lower prices when product prices spike. An interesting application of this is the potential for an ethane cracker operator to convert the economics of its cracker to those of a virtual naphtha cracker, by paying an integrated gas producer-processor a price for ethane indexed to naphtha-based ethylene production costs. 

Another opportunity for advancement in ethylbenzene synthesis is in the development of liquid phase processes that can handle low cost feedstocks, including dilute ethylene such as ethane/ethylene mixtures. The use of dilute ethylene has become increasingly attractive since it has the potential to debottleneck ethylene crackers. Currently higher temperature, vapor phase technologies can tolerate contaminants that enter with the dilute ethylene feed from FCC units. However, these same contaminants can accelerate catalyst aging in lower temperature, liquid phase operations because they are more strongly adsorbed at the lower temperatures. Acid catalysts that tolerate elevated levels of contaminants would facilitate the development of dilute ethylene-based processes. These same catalysts could be useful in applications where lower cost or lower quality benzene feeds are all that are available. 

Gas Authority of India (GAIL) is a government authority that markets gas produced by various upstream producing consortia. GAIL operates a 300,000 t/y ethylene cracker at Pata in Uttar Pradesh. The ethylene is processed downstream to HDPE and LLDPE. 

Petrochemical Processes 2005 , Hydrocarbon Processing, CD ROM, p. 71-81 See Hydrocarbon Processes 2005, Hydrocarbon Processes, CD ROM, p. 71-75 Muse StancU Co ethylene margins for US Gulf operations are published monthly in the Oil Gas Journal and described in Oil Gas Journal, September 16, 2002 S. K. Kapur, A. S. Laghate and W. M. Nouwen, Hydrocarbon Asia, Sept. 1996, p. 110 discuses the use of the SPYRO model in optimising cracker operations. 

The cracking of naphtha is carried out in all regions. The nominal capacity of the operations ranges from about 250 kt/y ethylene to operations producing over 1 million tonnes ethylene. There is good economy of scale and today s world scale crackers have a typical scale of 500 to 1000 kt/y ethylene, typically 850 kt/y. 

Although it may be unhelpful to push the distinction too far, there are noticeable differences in terms of process wastes between the commodity/ bulk/heavy chemical sector and fine chemicals. The former are generally much more efficient at putting atoms of reagent into product [21] which is just as well bearing in mind the scale on which they operate In most cases the product is the desired one although in some, for example cracking of hydrocarbons such as naphtha to produce ethylene, the yield of ethylene leaves room for improvement, and it has been said by some in the industry that operation of ethylene crackers takes one into businesses, due to the coproducts, which one has no wish to be in. 

Flaring and venting are two activities associated with oil and gas production. It is a combustion process used to dispose gases through vertical stacks or ground flares. Qatar is a world leader in gas and hydrocarbon processing. It has a world class Ethylene Cracker, Ras Laffan Olefins Company Limited (RLOC), of 1.3 million mtpa capacity. RLOC started up in April 15, 2010 and is operated by Qatar Chemical Company (QChem). 

In the preceding sections we have seen that an industrial steam cracker operating on naphtha is characterized by a broad range of products. The most prominent product, ethylene, accounts for less than 40% of all products. It would therefore be completely uneconomic to produce only ethylene and to use all other products only as the fuel for heating the steam cracker fiimace. 

During the 1950s the petroleum industry experienced a rapid development. A new abundant and cheap feedstock, naphtha, became available for the chemical industry and all ethylene needed for polyethylene and other chemical products started to be made from fossil feedstock. Combined with the development of cracker technology this has led to the very cost-effective steam crackers operated today. A typical size of a cracker built today has an ethylene production capacity of up to 1 metric tonnes/year. Gradually ethane and propane obtained either by separation from natural gas or from flare gas in oilfields have been used as feedstock. In areas with large oilfields and low population the latter provides a cheap feedstock. This is an important reason why most of today s investments in cracker capacity are made in the Middle East. 

Shanghai Secco Petrochemicals Co Ltd, a jv company of BP (London, UK www.bp.com), Sinopec and Shanghai Petrochemicals Corp, is building a world-scale complex at Shanghai Chemicals Industry Park in Caojing. The Secco complex, expected to begin operation in 2005, will comprise a 900 000 tpa, naphtha-fed ethylene cracker, plus downstream facilities with combined PE, PP and PS capacity of more than 1 million tpa, plus world-scale styrene, acrylonitrile and other olefins-derivative units. 

Production estimates for propylene can only be approximated. Refinery propylene may be diverted captively to fuel or gasoline uses whenever recovery is uneconomic. Steam-cracker propylene production varies with feedstock and operating conditions. Moreover, because propylene is a by-product, production rates depend on gasoline and ethylene demand. 

Since the bulk of butadiene is recovered from steam crackers, its economics is very sensitive to the selection of feedstocks, operating conditions, and demand patterns. Butadiene supply and, ultimately, its price are strongly influenced by the demand for ethylene, the primary product from steam cracking. Currently there is a worldwide surplus of butadiene. Announcements of a number of new ethylene plants will likely result in additional butadiene production, more than enough to meet worldwide demand for polymers and other chemicals. When butadiene is in excess supply, ethylene manufacturers can recycle the butadiene as a feedstock for ethylene manufacture. 

USC [Ultra Selective Conversion] A front-end process for improving the operation of catalytic crackers for making ethylene. Developed and offered by Stone Webster Engineering Corporation. 

Another contrarian, DSM in the Netherlands, had been a state-owned company before it became privatized, a process that began in 1989 and was completed in 1996. From its past it had inherited positions in fertilizers, industrial chemicals, and such intermediates as melamine and caprolactam as well as polyolefins, with access to basic olefins through its own crackers in Geleen, Netherlands. In 1997 DSM acquired the polyethylene and polypropylene operations of FIuls (VEBA) with the Gelsenkirchen site. The company had also diversified into elastomers, having purchased in the United States the Copolymer Rubber and Chemical Corporation, which contributed to DSM s expansion into the fields of ethylene propylene, styrene butadiene, and nitrile rubbers. DSM is also a supplier of industrial resins and engineering... 

In the current state of the techntdogy, the production capacity of a two-cell pyrolysis furnace is about 40,000 t/year of ethylene. Thus, a 400,000 t/year steam cracker comprises ten furnaces on naphtha and one or two used to pyroiyse recycled ethane One or two spare furnaces (10 to 15 per cent of the theoretical production capacity) are also normally provided, in order to compensate for the production dehcit due to decokmg operations. 

N) and aromatics (A). The octane rating (RON) is typically 55 or higher. Some straight-run naphtha contains high levels of aromatics which do not make good cracker feed. It has been proposed that such naphtha could be pre-treated to remove the aromatics prior to the cracking operation. This would improve ethylene yields and provide additional aromatics for downstream operations. ... 

This order of magnitude estimate is based on a hypothetical plant for the production of 500 kt/year of ethylene with a capital cost of 150 million. This is compared to the cost of a green-field ethane cracker of about 700 million. Process selectivity is assumed 100% with operating allowance for feed and fuel of 5.5% and 3% respectively. 

These reactions are reversible, and there is a dynamic equilibrium between carbon formation and removal. Under typical steam reforming conditions, reactions (46) and (48) are carbon - removing, whilst reaction (47) leads to carbon formation in the upper part of the tube [503]. With naphtha as steam reformer feed, irreversible pyrolysis (as in a steam cracker for ethylene production) with the sequence naphtha —> olefins—> polymers—- coke will occur. The mechanism of carbon formation and the determination of the risk areas in the reformer operating conditions on the basis of relevant equilibrium data are discussed in some detail in various publications [362], [363], [418]-[420]. 

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