Integrated complexes typically converted 3 to 20 wt. % of crude intake to petrochemicals[i] and are now pushing this to about 50 wt.% utilizing currently available conversion technologies. These complexes typically start with a mix of light to heavy crude diets. The heavier crudes and higher target yield of petrochemicals lead to a more complex refinery configuration. The petrochemistry building blocks typically include steam cracker and aromatics complex.[ii] The integrated complexes are driven by refinery conversion units (catalytic processes) as well as opportunities for improving overall economics by upgrading low value refinery streams to high value chemicals.[iii] Refinery processing objectives can be achieved through a combination of hydrogen addition technologies (like fixed bed, ebulated bed or slurry based hydrocracking of vacuum gas oil and resid), carbon rejection technologies (like FCC/RFCC, delayed coking, flexifluid coking etc.) and carbon concentration technologies (like deasphalting, visbreaking etc.). Steam cracker plants use a thermal cracking process and are highly flexible and can process a variety of refinery streams starting from light off gases to vacuum gas oils.[iv] Aromatics complex is a combination of processing units for converting naphtha and pyrolysis gasoline into benzene, toluene and xylenes.[v] Integrated facilities provide feedstock synergy and flexibility to adapt to future market changes in product quality specifications and product demand shifts.
Refinery businesses are looking for product diversification and vertical integration to secure market share, given the uncertainty about demand growth in fuels market. Steam cracking is a dominant technology for production of olefins and will remain so for the foreseeable future. Naphtha is the leading feedstock globally, and chemical companies constantly look for advantage feedstock for building and operating olefin complexes in a competitive and cyclical business environment. Shale related developments in North America resulted in abundant ethane feedstock supply at very attractive pricing based on cheap natural gas. Natural gas price is expected to stay relatively stable at lower levels. This changed the global energy dynamics of natural gas pricing relative to crude. Chemical companies, operating in regions of the world where most of the feedstock is sourced from crude oil, are constantly looking at the options for staying competitive in the changing marketplace. With most of the new refinery capacity being added in those regions of the world, it’s a logical option to build integrated refinery petrochemical complexes to stay competitive. The case studies, based on different levels of integration between refinery and petrochemical complex, presented in previous publication demonstrate improvement in overall economics. The diversification of product portfolio helps in increasing the production of higher value products and minimizing the processing costs and thus positioning integrated businesses to be competitive in rapidly changing marketplace.i Integrated complexes are highly capital intensive and complex to plan and implement. It requires a great amount of understanding of the different refining and petrochemical technologies for evaluating the configuration options, along with approach towards integration, to meet the desired business objectives over the long-term life cycle of these facilities.[vi] The scale of these projects is enormous and some in the industry refer to these as “giga-scale”.[vii] Most of these large scale projects are joint venture ownerships (multiple partners) because of large scale investments (tens of billions of dollars). The success of these joint venture lies in understanding of all the aspects of these ventures (strengths of each partner, business drivers, synergy, understanding of technologies/operation and facility operating plan, clear and crisp contractual arrangements based on sound understanding of dynamics that impact the projects/plants over the course of their life etc.) early and upfront.
There is a further push to increase the petrochemicals yield to 70-80% level (Saudi Aramco and Chevron Lummus Global signed a technology development agreement to commercialize the crude oil to chemicals technology).
Many chemical companies and technology suppliers have focused their effort on crude and condensate sources to directly feed these to the ethylene plants.[viii],[ix] These developments are targeted to eliminate the needs of separation/processing facilities to reduce the overall investment and energy consumption. These technologies are generally limited to lighter crudes of suitable quality for achieving optimum results. These lighter crudes normally have a heavy, non-volatile tail (typically referred as residue or resid). This residue material needs to be separated from the feed entering the high temperature areas of the steam cracking furnaces as this leads to coke build-up. Most the developments to handle these crudes relate to separating the residue from the feed prior to entering high temperature zones of the steam cracking furnaces. Some plants in Asia and Europe have successfully cracked lighter crudes and condensates. Most of the focus previously (in 1960s and 1970s) was related to development of technologies that allowed full vaporization of heavier feeds (straight run or hydrotreated/ hydrocracked gas oils, vacuum gas oils) at conditions that avoided the problems of heavy fouling in convection sections of the steam cracking furnaces. These technologies have been applied successfully in many industrial applications.
For heavier refinery streams and crude oil cracking, many processes were developed and tested from 1960 to early 1980s.[x] Most of these processes were based on fluidized bed cracking. Lurgi developed the sand cracker using sand as heat carrier.[xi] Ube used inorganic oxide as heat carrier.[xii] Kunugi and Kunii process used coke as a heat carrier.[xiii] Gulf Chemical and Stone&Webster jointly developed a thermal regenerative cracking process using solid heat carriers in the fluid bed.[xiv] The development of these processes stopped after crude oil prices collapsed in early 1980s and none of these processes achieved commercialization.
Steam cracking, to produce basic building blocks – ethylene/propylene/butadiene/butenes/ aromatics, is the most versatile and critical technology that drives the integration approach and effective management of hydrocarbons. In upcoming blog, I will present a case study that will highlight options for integration and their impact on steam cracker economics.
[i] Kapur et. al., PTQ Q3 2009, “Competitive Driving Force for Integration”, pages 17-23
[ii] Kapur et. al., Hydrocarbon Processing – February 2009, “Why Integrate Refineries and Petrochemical Plants”, pages 29-40
[iii] Kapur et. al., 20th Ethylene Producers Conference April 6-10, 2008 New Orleans, “Catalytic Routes to Olefins Shaping the Integrated Complex Configuration”, paper number 219f
[iv] Sanjeev Kapur, RLPA Conference 1994 Singapore, “Pyrolysis of Hydrocarbons to Olefins”
[v] Zhou et. al., Hydrocarbon Processing – November/December 2012, “Improve Integration Opportunities for Aromatics Units – Parts 1 and 2”
[vi] Sanjeev Kapur, International Petroleum Refining – April 2011, “Planning is imperative for the Success of an Integrated Facility”, pages 66-69
[vii] Interview of Joseph Brewer of Sadara by Ashraf Ayoub of ECC, Hydrocarbon Processing Website – June 19, 2018” http://www.hydrocarbonprocessing.com/news/2018/06/when-mega-goes-giga-a-discussion-on-the-sadara-petrochemical-complex
[viii] Stell et. al., Patent US7588737B2, “Process and Apparatus for Cracking Hydrocarbon Feedstock Containing Resid”
[ix] K. M.Sundram, Patent US20160097002A1, “Thermal Cracking of Crudes and Heavy Feeds to produce Olefins in Pyrolysis Reactor”
[x] Kapur et. al., ENI Encyclopedia of Hydrocarbons – Volume II/Refining and Petrochemicals, “Section 10.5 Ethylene and Propylene”, pages 551-589
[xi] Schmalfeld P., Hydrocarbon Processing and Petroleum Refiner, vol. 42, 1963, “How Lurgi Improved Sand Crackers”, pages 145-148
[xii] Matsunami et. al., Hydrocarbon Processing – November 1970
[xiii] Kunugi D., Chemical Engineering Science, vol. 35, 1980, “Chemical Reaction Engineering and Research and Development of Gas Solid Systems”, pages 1887-1911
[xiv] Ellis et. al., Proceedings of AIChE National Meeting April 1981, Houston, “TRC. A New Olefins Technology”