Oct-2011

Refinery expansion and oil quality upgrading

Optimisation of resources and effective integration of clean fuels technology enable older refineries to better match the economic performance of new plants

Sun Lili
Sinopec Engineering Incorporation

Article Summary

This article analyses the differences between older refineries and advanced refineries with respect to policy requirements, target market demand, advanced process technology, resource utilisation, energy conservation, environment protection and economic benefit. Through case analysis, some effective measures are taken by exploiting the potential to enhance comprehensive refining capacity, improve oil product quality, optimise the product mix, and achieve economies of scale.

China’s refining industry has accelerated its restructuring since the beginning of the 21st century. Production of clean oils has been increased through the wide adoption of clean fuels production technologies. Measures to continuously increase depth of oil processing, adapt to sour, heavy oil processing and further improve light oil yield have been pursued. Also, competitive, integrated refining and petrochemical complexes have been established in coastal areas to ensure the requirements of energy supply to support national economic development are met.

Currently, Sinopec owns a large number of coastal and inland refineries that were built in the 1970s and the 1980s. Since the “10th Five-Year Plan”, the refineries have accelerated their technical transformation, optimised their allocation of resources, adjusted the product mix, notably improved their overall strength and competitiveness, and have achieved a refining capacity of about 5.0 million t/y. However, there are still some differences between these refineries and advanced refineries. These differences, in particular, relate to industrial policy requirements and target market demand, the level of advanced process technology, resource utilisation, energy conservation, environment protection and economic benefit. Therefore, it is necessary to enhance their performance in a number of respects: raising refining capacity; improving oil product quality, optimising the product mix; achieving economies of scale; and exploring a process route with the characteristics of old refineries by exploiting their potential.

Refinery expansion and oil quality upgrading
Goals for the development ofolder refineries
To comply with the newly issued Circular Economy Promotion Law of the People’s Republic of China and the Cleaner Production Promotion Law of the People’s Republic of China, petrochemical plants or refineries, especially older refineries, need to improve their immediate environment to establish a clean performance for sustainable development. As pipeline oil becomes poorer in quality, refineries need to improve their capacity for – and adaptability to – low-quality crude oil processing, to create the conditions for further improving their environmental protection measures and increasing their profitability. The Chinese government aims to adopt tougher quality standards for gasoline and diesel; hence, refineries need to improve measures for gasoline and diesel production by means of technical transformation and improvement, so as to upgrade the quality of crude oils and to supply the market with cleaner oil products. Refineries need to work out an optimal combination of oil, gas and coal, so as to take full advantage of the extensive resources of China.

Development roadmap for older refineries
The quality of crude oils needs to be upgraded by phasing out outmoded process units and technically transforming and improving older refineries. Relying on existing facilities in the older refineries, production needs to be raised to increase oil throughput, so as to provide cleaner oil products for the local economy. Resource allocation needs to be optimised and product costs reduced by adjusting unit configuration and product mix, to further increase the overall competitiveness of the refineries.

Plan for refinery expansion and oil quality upgrading
Optimisation of processtechnology
Crude oil structures and product demand need to be analysed in relation to problems in the existing process flow of the older refineries. These problems include low adaptability to sour crude oil processing, low heavy oil conversion, poor quality of oil products and single product mix. Relying on the existing crude oil processing capacity of the older refineries, a clean vacuum residue desulphurisation (VRDS) FCC process for heavy oil processing is recommended, based on a process comparison to increase adaptability to sour crude oil processing and to improve heavy oil conversion. A catalytic reformer (CCR) unit, an S-Zorb unit and a diesel hydrogenation unit are to be installed to upgrade comprehensively the quality of gasoline and diesel to national III/IV/V standards. While ensuring oil production, the process schemes and operating conditions of the FCC and CCR units are optimised, the production of raw materials such as propylene, benzene and paraxylene are increased appropriately, and the product mix is optimised, thus creating the conditions for the development of a downstream petrochemical industry. A light ends recovery unit and a hydrogen-rich gas purification unit are also to be installed. For example, FCC dry gas is sent to the styrene unit as the feed to recover and produce high-value products and to increase the resource utilisation rate.

The application of such measures for integrating refining and petrochemical production can not only lower the production costs of the refineries, but can also significantly increase the added value of their products and enhance their profitability and overall competitiveness.

Comprehensive energy utilisation
Refinery-wide energy utilisation controlled by complex systems engineering organises heat integration between units as well as the distribution of cold and hot sources based on the actual conditions of each production unit and utility, so as to ensure the smooth operation of closely grouped units and to maximise operational efficiency and value.

Taking advantage of a centralised arrangement of units, an integrated study of refinery-wide energy utilisation is carried out. The focus is shifted from energy optimisation of a single unit to a combination of unit optimisations with refinery-wide optimisation, in order to improve the energy utilisation level of the refineries.

By adopting low-temperature heat utilisation technologies, a low-temperature heat utilisation plan can be further optimised and the application of low-temperature heat power generation or refrigeration technology can be enhanced.