Refinery design in China
Poor-quality crude oils and strict environmental regulations promote the use of technologies that favour energy savings and environmental protection
Sinopec Engineering Incorporation
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According to statistics, refining capacity in mainland China reached 575.27 million tons in 2010, 1.77 times the 2000 figure. Sinopec processed 144 crude oils in 2010, with a total processing capacity of 212.972 million tons. Classified according to crude oil properties, high-sulphur and high-TAN crude oils account for 49.58% of the crude oil processed, representing a year-on-year increase of 0.64%, and sour, acid, high-sulphur and high-TAN crude oils account for 80.66% of the crude oil processed, representing a year-on-year increase of 0.68%.
In compliance with the increasingly strict environmental regulations of countries worldwide, standards for gasoline and diesel oil are continuously being upgraded. The European Union, Japan and Korea limit the sulphur content of motor gasoline and diesel to below 10 ppm, and North America and Australia specify a sulphur content of 30-50 ppm. It is predicted that the production of gasoline and diesel oil with a sulphur content of less than 10 ppm will exceed 60% of world gasoline and diesel production this year. The main trend of development in the future is for ultra-low sulphur gasoline and diesel oil.
Since 2010, China has limited the sulphur content of gasoline to below 150 ppm, but still has a long way to go compared with developed countries. Also, China has limited the benzene content of gasoline to no more than 1%, which is equivalent to the figure specified by Europe, America, Japan and Korea. In 2011, a new standard for motor diesel was implemented in China, which significantly lowered the sulphur content of diesel oil.
The corresponding national standard for integrated wastewater discharge is continuously upgraded. Chemical oxygen demand (COD) in wastewater from refineries built after 1998 should be less than 60 mg/l. Currently, most refineries are following Grade II or Grade III wastewater discharge standards.
The corresponding national standard for the integrated emission of air pollutants is continuously upgraded. SO2 and NOx in waste gas emissions from refineries built after January 1997 should be less than 960 mg/l and 240 mg/g, respectively.
Currently, disparity exists between actual emission of pollutants and the requirements of the new standard, and special attention should be paid to NOx control.
Gap analysis between refineries
Waste of petroleum resources
There are quite a lot of small-scale refineries in China, with a total processing capacity above 50 million t/y in 2010. Small-scale refineries are characterised by simple process technologies, poor-quality products, high energy consumption and low environmental protection levels. According to statistics, light oil yield in a small-scale refinery is 10% lower than that in a large-scale refinery, and annual light oil production in a small-scale refinery is five million tons less than that in a large-scale refinery.
Low use of petroleum resources
The average capacity of Chinese refineries is lower than the world average, and most refineries select decarbonisation processes including coking for heavy oil processing, resulting in high energy consumption, high material consumption and low utilisation of petroleum resources.
According to the 2010 statistics of refineries in Sinopec and PetroChina, the average light oil yield is 76.41%, while the world’s advanced level is 80.8%. The average comprehensive self-sufficiency rate is 5.11%, while the world’s advanced level is below 4%. The comprehensive commodity rate is 94.33%, while the world’s advanced level is above 96%, and the processing loss rate is 0.59%, while the world’s advanced level is below 0.45%.
Currently, the consumption of transportation oil and chemical oil constitutes a relatively low proportion of petroleum consumption. Petroleum resources are not utilised effectively and rationally.
Process technology gap leads to high energy consumption
The performance in energy consumption of most refineries in China lags considerably behind the world’s advanced level. In 2010, the Energy Intensity Index (EII) of refineries in Sinopec and PetroChina was 87, while the world’s advanced level was below 78 and at the highest level was below 70.
Currently, oil product quality in China still lags behind that of developed countries. To meet corresponding quality standards, new units should be installed, leading to higher energy consumption and energy loss.
The energy consumption of a refinery accounts for 6-10% of the crude oil processed, depending on the complexity and quality upgrading level of the refinery. The figure is even higher in some refineries.
Treatment of waste gas, wastewater and solid wastes to be strengthened
Flue gas from refinery furnaces and boilers contains relatively high levels of harmful substances, including SO2 and NOx, and the treatment of wastewater and solid wastes needs to be further strengthened. The average SO2 in flue gas is 550 mg/m3, while the world’s advanced level is below 400 mg/m3 and the world’s leading level is below 200 mg/m3. The average COD in wastewater is 100 mg/l, while the world’s advanced level is below 60 mg/l.
Developed countries have realised automatic monitoring of environmental pollution and have integrated the environmental monitoring system of refineries into local environmental monitoring networks for social and public supervision. Chinese refineries should further strengthen their environmental monitoring measures.
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