FOCUS: REFINING Engineering firm has designed refinery of the future

Makoto Inomata, Kyohei Sato,
Yu Yamada, Hajime Sasaki
JGC Corp.
Yokohama, Japan

The purpose of the team was to forecast the environment facing the refining industry in Japan, long-range energy supply and demand, population and economic growth, traffic system trends, and technology and science progress through the middle of the twenty-first century.

The REF-21 team also was charged with developing a conceptual design for the future refinery. The team proposed four types of configurations for the so-called new-generation refineries. These schemes included some new technologies that it deemed commercializable by 2000. JGC evaluated these new-generation refinery schemes in terms of overall yields, energy efficiencies, emissions, and economics, as compared with existing refineries.

JGC also has developed an amenity design program (ADP), and is applying it to a refinery in Japan to produce a new-concept operation center. Through amenity design, JGC intends to improve the operating environment for employees in order to enhance overall productivity.

Business environment

Fig. 1 [47241 bytes] summarizes the environment facing the refining company in Japan.¹ It is evident from Fig. 1 that Japanese refiners are facing the same pressures as their counterparts in other regions: supply/demand changes, environmental requirements, energy conservation issues, and flexibility needs, to name a few.

Fig. 2 [32609 bytes] shows the refined products demand outlook in Japan. Between now and 2010, demand for white products, such as diesel fuel and gasoline, will increase steadily. Average growth in white oil demand will be about 1.7% annually through 2010. The heavy fuel oil market will be weak, with decreasing demand.

In the Asia/Pacific region between 1991 and 2000, gasoline demand will grow 3.9%/year, while gas oil demand will increase 4.4%/year. Crude oil demand in the region will increase steadily because of strong demand for white products.

Fig. 3 [33319 bytes] shows the API gravity and sulfur content outlook for the crudes processed by Japanese refiners. Crude oil became increasingly lighter from 1980 to 1990. In the last 4 years, however, the gravity and sulfur content of Japan's crude slate have both increased steadily.

These trends will continue in the future. This projection is backed up by data on world oil reserves, which show that Middle East crudes, which are generally heavy and high in sulfur, constitute about 65% of world crude reserves.²

These trends mean that, in the future, the refining industry will need to process heavier crudes and upgrade the bottom of the barrel. In Japan, current gasoline qualities are:

• Benzene content, 2.6 vol %

• Average RON, 92.3

• Sulfur content, 26 ppm(wt).

In the near future, the benzene content will be reduced to less than l vol % by a combination of environmental pressures and commercial needs. Average octane number will increase to about 93 during the next decade, because of increasing market share for premium grades.

The sulfur content of gas oil in Japan is 0.15 wt %, but will be reduced to 0.05 wt % this year. The cetane index of gas oil is about 59.

In the year 2000, however, more severe specifications may be required. Furthermore, there is likely to be continued pressure to reduce environmental pollution not only from the fuels refineries produce, but also from refineries themselves. These pollutants are likely to include SO2, CO2, NOx, and waste products.

Relaxation of Japanese regulations will allow imports of oil products, power generation in the refinery, power exports out of the refinery, and longer continuous operation without legal requirements to shutdown for inspection.

Some Japanese refineries are trying to operate continuously for more than 2 years. The bottleneck in this approach is continuous operation of residual oil hydrotreating, hydrocracking, and residual fluid catalytic cracking (FCC) units. Long continuous operation contributes to the profitability of a refinery.

Recently, power companies accepted the plans of three Japanese refining companies' to introduce power generation facilities. Other refiners are conducting feasibility studies of independent power production.

Based on the business environment facing the refining industry, JGC has proposed ten key ideas in designing the new-generation refinery. They are:

1. Bottoms upgrading

2. Minimum emissions

3. Clean products

4. Minimum maintenance

5. Long-term operation

6. Production center

7. Amenity

8. Safety

9. Flexibility

10. Simplicity.

Refinery configurations

JGC has surveyed developing refining technologies which are expected to be commercialized by the beginning of the twenty-first century. The technologies have been evaluated and screened using the ten key ideas.

The design crude oil for the REF-21 refinery is Arabian Heavy, and design capacity is 150,000 b/sd. The project team has determined four configurations for new-generation refineries: flexible refinery, maximum gasoline refinery, power generation refinery, and petrochemical refinery.

Flexible refinery

Table 1 [29158 bytes] shows new technologies used in the flexible refinery scheme. Biocatalytic desulfurization has been added, as has a single hydrotreating unit, coupled with simpler distillation, advanced FCC, solid acid alkylation, slurry-type hydroconversion, and integrated gasification combined cycle (IGCC) with associated methanol production.

Fig. 4 [48571 bytes] shows the configuration of a flexible refinery. This scheme allows a refiner to adjust the yield balance of gasoline and diesel oil, depending on demand patterns. The amount of feed to the vacuum gas oil (VGO) hydrocracker and to the advanced FCC unit are adjustable, according to the desired yield balance.

About 30% of the sulfur in the crude oil is removed by biocatalytic desulfurization of the whole crude using an enzyme catalyst at atmospheric pressure and mild temperatures (Fig. 5) [26717 bytes].³ Biocatalytic desulfurization has many advantages compared to the traditional hydrodesulfurization (HDS) process, such as lower capital and operating costs, low-temperature and low-pressure operation, and no hydrogen requirement.

Aerobic enzymes selectively desulfurize benzothiophene and dibenzothiophene in the crude. Sulfur is removed from the oil as water-soluble sulfate ion. Calcium hydroxide or ammonia is used to neutralize the sulfate, producing high-purity calcium sulfate or ammonium sulfate.

Energy BioSystems Corp., Houston, and Japan's Petroleum Energy Centre, have been developing the biodesulfurization technology. Although substantial innovations in biocatalysts, reactor design, and product separation will be required before biodesulfurization (BDS) replaces conventional hydrodesulfurization, BDS allows the new-generation refinery to reduce hydrogen consumption and to flexibly cope with increasing sulfur content in crude oil.

Desulfurized crude oil is separated in a flasher-type distillation unit into an atmospheric residue and a stream containing gas oil and lighter fractions. This stream is hydrotreated in a single hydrotreating unit. The product is then separated into gas oil, kerosine, heavy naphtha, light naphtha, and gases. Heavy naphtha is fed to the continuous catalyst-regeneration reformer.

JGC has developed this process for a small-scale refinery.

In today's refineries, regardless of capacity, crude oil is separated into several fractions in the distillation unit and each fraction is hydrotreated independently. But, for construction of small refineries, a compact, low-capital-cost flow scheme is desired.

The single-HDS-unit scheme will simplify the construction and operation of a refinery of any size. The crude unit will be smaller and simpler, and the amount of equipment will be much less than for a conventional combination of desulfurization units. The result will be a reduction of capital costs, maintenance costs, and plot area.

For upgrading vacuum residues, a hydroconversion process is adopted. This process has a conversion rate as high as 95% using advanced microcatalyst. Bottoms upgrading and long-term operation will be achieved.

Processes that use a fluidized bed, ebullated bed, or slurry bed can be applied in the REF-21 flow scheme to achieve long-term operation and stable product quality. Ebullated-bed processes are adopted for the VGO hydrotreater and hydrocracker. In addition, continuous regeneration technology will be used in more processes in the future.

VGO is fed into an advanced FCC (AFCC) to produce FCC gasoline and raw materials for reformulated gasoline. Light ends from the AFCC unit are upgraded into high-octane gasoline components by oxygenates production and alkylation.

Solid acid alkylation technology is adopted for the alkylation process. The heavier residues are used for steam and power generation by gasification, associated with combined cycle generation and hydrogen production.

Some new processes

An AFCC unit increases bottoms cracking and desirable products, and decreases dry gas and coke production. By contrast, in resid FCC units, the conversion of feedstock to gasoline and gases is 5-10% less than optimal conversion.⁴

To realize a truly advanced FCC process, catalysts and processes must be improved to achieve maximum conversion coupled with increased yield of desirable products. Table 2 [26338 bytes] shows some new FCC processes that allow higher conversions and better selectivities.⁵⁶

UOP's Millisecond Catalytic Cracking (MSCC) process uses a downflow-type contactor and Sinopec's deep catalytic cracking (DCC) process and its FCC process for maximum production of gasoline, and LPG (MGG) applies new zeolites. The AFCC adopted in this scheme uses oxygen-rich gas for regeneration to reduce the amount of flue gas and NOx emissions.

Key technology for an aFCC catalyst is hydrothermal stability of structure at around 850° C. and high metals capacity. An advanced FCC catalyst, which has a high-integrity crystalline structure with a high silica-to-alumina (Si/Al) ratio, has been developed, although it is still experimental.

With the advent of reformulated gasoline, alkylate is growing in importance because of its high octane and low vapor pressure. Solid acid alkylation has potential environmental and safety advantages over conventional processes that use hydrofluoric and sulfuric acid as catalyst.

The key to developing this process is the catalyst and catalyst regeneration. Most solid catalysts under development still make use of acids that contain halogen.^7-9 These catalysts are capable of regeneration under mild conditions. The octane-barrel of alkylate produced using these catalyst would be equal to or better than that from conventional processes.

Integrated refineries

In a power generation refinery, asphaltenes from deep solvent extraction of vacuum residue are used as feed for power generation. The recovered deasphalted oil (DAO) is then processed in a downstream vacuum oil HDS unit.

The incorporation of a carbon-rejection process, such as solvent deasphalting or coking, to FCC and power generation is an attractive approach for bottom-of-the-barrel upgrading, because low-value vacuum residue can be converted into valuable products and utilities.

Carbon-rejection has some advantages over hydroconversion, such as lower investment cost and no hydrogen requirement. However, cokes and pitch are solid fuels with fire hazard and dust problems, and they require yard facilities for loading, storage, and transportation. Consequently, the utilization of pitch or coke as a salable liquid fuel plays a very important role in the overall economics of the carbon-rejection configuration.

JGC has developed a mixture of 70 wt % residue and 30 wt % water to convert pitch and coke to a salable liquid fuel. Table 3 [21117 bytes] shows the properties of the residue-water mixture (RWM) compared with a coal-water mixture (CWM) and Orimulsion.

The carbon content of RWM is 65 wt %. RWM is pumpable, transportable, and capable of being burned in a conventional boiler.

In the petrochemical refinery, LPG, light naphtha, and lower olefins, which are surplus in the refinery, are upgraded to aromatics and hydrogen. Aromatics and reformates are converted to benzene and xylene in an aromatics complex.

Ethylbenzene is produced by reacting dilute ethylene from the AFCC unit with benzene. Hydrogen evolved in aromatics production is used in the refinery.

In the petrochemical refinery, consumption and production of hydrogen are balanced without the need for a hydrogen production facility. Petrochemicals and energy production form a synergy with oil refining, in terms of utilities, hydrogen, and upgrading.

Performance, economics

Fig. 6 [37798 bytes] shows white oil yields, emissions, and utility consumption for the new-generation refinery compared with conventional refineries. In the refinery of the future, white products yields are increased without producing heavy fuel oil. In addition, NOx and SOx emissions and energy consumption per unit of white oil production decline, compared with existing refineries. This is a result of the incorporation of more-efficient processes, such as biodesulfurization, single-unit HDS, AFCC, hydroconversion, and IGCC.

JGC has evaluated revenues from the new-generation refinery, based on various price scenarios for crude oil and refined products. Bottom upgrading, long-term continuous operation, and synergy with petrochemical and energy production contribute largely to the profitability of the refinery of the future.

Amenity design

The preceding sections described the technological considerations of a twenty-first century refinery. For personnel issues related to the operation of a complex refinery, JGC has proposed a production center and so-called amenity design.

The production center will process and analyze not only the operating data, but also on-line facility inspection information, crude supply information, and product market data. The goal of the production center is to merge refinery operation with home office management to economize on personnel expenses and to optimize refinery and company performance.

For JGC's amenity design program (ADP), statistical analyses were performed on personal preference data. The data were collected through questionnaires and by interviewing refinery personnel at all levels.

Many Japanese industries, including refining, have, to date, expended much labor improving production facilities mainly from the hardware standpoint, with top priority given to functions and efficiency. The productivity of a refinery, however, depends on the productivity of not only hardware factors (that is, facility functions), but also "soft" factors, with emphasis on personnel satisfaction.

To enhance overall productivity in the new-generation refinery, companies must pay more attention to the improvement of the facility environment. The demands that next-generation refineries are required to deal with may be categorized into factors that:

• Offer greater amenity to employees

• Improve communication with local communities

• Enhance corporate identity (by publicizing business activities).

These three types of demands are thought to be closely connected. To meet these demands, JGC has proposed an approach from the facility standpoint called "refinery amenity design."

Amenity design has beneficial effects on employees, including:

• Arousing keenness to work

• Imparting a sense of pride in one's work

• Improving work quality and efficiency

• Lengthening the service period of employees.

These enhancements not only improve work efficiency, but also reduce "misoperations" or accidents. This will lead to improved productivity in the "soft" areas, and should have a large impact on the local community.

Fig. 7 [40937 bytes] is a chart of amenity engineering work flow.

JGC's ADP analysis uncovered a number of "amenity problems." In one refinery, for example, the on site control rooms lacked windows, thus producing a very enclosed atmosphere. The responses to a questionnaire revealed that many employees strongly desired an improved work environment.

A new control room was built off site. It made use of as much natural lighting as possible. In addition, plants, glass walls, and an atrium have been added.

The control room is located in the center of the first floor, and the second floor above was left open to provide operators a sense of expanse. Office spaces have been provided on both sides of the control room. To improve communication with the control room, these spaces are not walled.

Based on the results, JGC recommends the new-concept amenity design for industrial facilities.¹⁰

Future refineries

There is no single optimum configuration for refineries of the future. Many factors contribute to the decision-making process. Some of these factors are specific to the individual refiner.

JGC's REF-21 approach allows an analysis of the technical and economic merits of different process schemes and new technologies. More-efficient catalysts, technologies, and processes will be developed in the foreseeable future.

These advances will enable refiners to meet the challenges of increased availability of heavy, sour crude oils, while satisfying light products demand, upgrading quality specifications, and improving environmental performance.

Acknowledgment

This study has been sponsored by the Petroleum Energy Center in Japan, which is supported by the Japanese Ministry of International Trade & Industry.

References

1. Inomata, M., "New generation refinery," Middle East Refining & Petrochemicals Conference & Exhibition, PETROTECH96, Bahrain, 1996.
2. Inomata, M., "Future direction of refinery in environmental aspects," Fifth China-Japan Joint Seminar on Research and Technology for Petroleum Refining, Jiujiang, China, 1994, p. 53.
3. Monticello, D.J., "Biocatalytic desulfurization," Hydrocarbon Processing, February 1994, p. 39.
4. De Jong, K.P., "Efficient catalytic processes for the manufacture of high quality transportation fuels," Catalysis Today, Vol. 29, 1996, p. 171.
5. Kauff, D.A., Bartholic, D.B., Stevens, C.A., and Kein, M.R., "Successful application of the MSCC process," NPRA Annual Meeting, 1996, Paper NO. AM-96-27, San Antonio.
6. Li, C., Li, Z., and Huo, Y., "New catalytic processes for maximum light olefins," Fifth China-Japan Joint Seminar on Research and Technology for Petroleum Refining, Jiujiang, China, 1994, p. 52.
7. Rhodes, A.K., " U.S. refiners must increase alkylation capacity to meet demand," OGJ, Aug. 22, 1994, p. 49.
8. Rao, P. ,and Vatcha, S.R., "Solid-acid alkylation process development is at crucial stage," OGJ, Sept. 9, 1996, p. 56.
9. Sogaard-Anderson, P., Geren, P.M., and Hillier, W.J., "Retrofit of alkylation and polymerization plants using the Tops e fixed-bed alkylation process," NPRA Annual Meeting, 1996, Paper No. AM-96-53, San Antonio.
10. Yamada, Y., "Amenity designed refinery for the next generation," NPRA Annual Meeting, 1996, Paper No. AM-96-10, San Antonio.

The Authors