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Device energy saving starts from the "heart"
Ethylene is a leader in the petroleum and chemical industry and one of the six key energy-consuming industries in the petrochemical industry in China. Reducing the energy consumption of the ethylene industry is crucial to promoting the entire petrochemical industry to achieve energy conservation goals. The cracking furnace is the key equipment of the ethylene plant, and it is also a large energy consumer of the ethylene plant. It consumes a lot of water, natural gas and electricity. It is reported that the cracking furnace has been using normal temperature air in the past, not only that the combustion temperature of the furnace is difficult to be effectively controlled, but also that when the cracking furnace burner heats the air, the circulating system of the furnace must reduce the temperature of water vapor, during the process of “one lift and one dropâ€, It consumes a lot of energy. From this calculation, the energy consumption of the cracking furnace accounts for 50% to 60% of the total energy consumption of the production. Therefore, energy conservation must begin with the “heart†device, the cracking furnace, optimize the operation mode of the cracking furnace, reduce the energy consumption of the cracking furnace, and spare no effort to increase the efficiency.
In December 2002, PetroChina Daqing Petrochemical, the northernmost petrochemical plant in China, took the lead in installing air preheating and energy-saving devices on three ethylene cracking furnaces. The energy saving effect was particularly significant, and the investment was recovered in those years. In the second year, the plant installed the energy-saving device on eight ethylene cracking furnaces with an annual output of 350,000 tons. After that, Sinopec-owned ethylene companies Jilin, Lanhua, and Dushanzi Petrochemical also successively implemented this energy-saving project. On November 27, 2003, Yuan Chonglun and four other designers applied for a patent on the air preheating system and method for the bottom burner of an ethylene cracking furnace.
At the Sinopec Energy Conservation Technology Exchange Conference held in Zhengzhou in October 2004, the air pre-energy-saving technology for cracking furnaces attracted the attention of China’s leading ethylene giant Sinopec, and began piloting at Maoming Petrochemical. In 2005, Sinopec held an energy conservation technology promotion and appraisal meeting at Maoming Petrochemical Plant. The energy conservation technology was ranked first in the five advanced technologies promoted in the ethylene industry, and was fully promoted in its eight ethylene companies. At present, Sinopec has completed the energy-saving transformation of 85 units with 100 cracking furnaces. According to the difference in the temperature of the waste heat source, the amount of fuel saved generally accounts for 1% to 6% of the fuel consumption of the entire furnace. Based on this calculation, nearly 65,000 tons of fuel will be saved each year, and the energy-saving benefit will be RMB 124 million per year for each ton of fuel.
The system operates without external power
Song Xiaofeng, general manager of the Thermal Engineering Division of the Beijing Aerospace Power Research Institute, said that the system energy saving method they invented was to add air preheating and energy-saving devices to the bottom burner of the ethylene cracker. According to the researcher Yuan Chonglun, there are four principles for reducing the energy consumption of cracking furnaces: First, the choice of waste heat sources must be based on the waste heat resources (such as low-pressure steam that is vented) or the waste heat resources that need to be recovered ( Such as boiler sewage, cracking furnace quench water, etc.) Second, it must be two-way energy saving, not only the use of the device's residual heat to save fuel consumption, but also make the waste heat device to reduce the secondary energy consumption, so as to achieve the purpose of energy saving; Third, energy-saving tube The operation of the network system requires no external power consumption, completely solves the technical problems through design, and completes the energy transfer through the internal cycle process to achieve the goal of pure energy saving; Fourth, the requirement for flexible operation of the device, open and stop freely, and meet the needs of process parameter fluctuations , No need for automatic control equipment, no additional operation and maintenance personnel.
Chemical companies have application conditions
The use of low-temperature heat sources has always been a difficult problem to be solved by chemical companies in energy conservation and emission reduction. The pyrolysis furnace air waste heat technology makes full use of the device's residual heat resources to heat the combustion air in the cracking furnace to achieve the purpose of energy saving. It uses a low-temperature heat source (usually less than 150°C) and does not require a high heat source. Therefore, companies using industrial furnaces and low-temperature heat sources can use this technology.
It is reported that after several years of technology promotion and continuous improvement, the technology has achieved point-to-face promotion in ethylene plants. Sinopec's 85% ethylene plant has used this technology and is promoting it on new ethylene projects. After the successful implementation of the four major ethylene projects, it has also been widely promoted conditions. With the gradual maturity of the application in the cracking furnace, at present, the technology can already be applied to other equipment such as industrial furnaces. The pure energy-saving technology of this province is completely suitable for China's national conditions, with less investment and quick results, and it is in line with the new concept energy-saving technology of energy recycling.
Chemical plant energy needs to do "heart surgery"
In the National Development and Reform Commission recently announced the "National Key Energy Technology Promotion Directory (first batch)", a cracking furnace air residual heat technology for ethylene cracking process will focus on promotion in the petroleum, petrochemical, and chemical industries. This technology skillfully uses the heat energy technology of liquid rocket engines to successfully recycle the steam and waste liquids from the recycling plant to a new ethylene cracking furnace. This technique, known as the air preheating of cracking furnaces, was successfully developed by the Beijing Aerospace Power Research Institute and is the first of its kind in China and even in the world. After more than 80 cracking furnaces of Sinopec have been transformed with this technology, the annual fuel cost can be saved by hundreds of millions of yuan.