Use of liquefied natural gas

2. Domestic research status

As early as the 1960s, the State Science and Technology Commission formulated the development plan of LNG, and completed the industrial test in the mid-1960s, Sichuan Petroleum Administration Weiyuan Chemical plant has the earliest industrial production unit of natural gas cryogenic separation and liquefaction, in addition to the production of He, but also the production of LNG. In 1991, the plant provided 30tLNG as rocket test fuel for the Space Department. Different from the foreign situation, the domestic natural gas liquefaction research is aimed at small-scale liquefaction process, and the related literature has been published more. The following is a brief introduction to the existing domestic natural gas liquefaction plant process.

In 2011, the CRN value of the market sales of China's LNG industry was about 80%, of which the proportion of the three state-owned enterprises of petrochina, Sinopec and CNOOC reached nearly 60%, and the sales areas were mainly concentrated in Tianjin, Shandong, Guangdong, Xinjiang and Shaanxi. In terms of LNG imports, by the end of 2011, China had put into operation five LNG receiving stations, with a total receiving capacity of 15.8 million tons per year. When completed by 2014, China's LNG receiving capacity will reach 33.8 million tons/year. China's natural gas geological resources are estimated to exceed 38 trillion cubic meters, the prospect of recoverable reserves is promising, according to the international standard, is expected to be recoverable reserves of 7-10 trillion cubic meters, recoverable 95 years, in the world is relatively rich in resources in the country. The land resources are mainly concentrated in Sichuan Basin, Shaanxi-Gansu-Ningxia region, Tarim Basin and Qinghai Province, while the sea resources are concentrated in the South China Sea and East China Sea. In addition, there are some resources available in the Bohai Sea, North China and other areas. Due to the lack of effective utilization of resources after exploration, and the lack of matching policies, the unreasonable gas use structure has restricted the healthy development of China's natural gas industry to a certain extent. However, with China's social progress and economic development, it will be an inevitable trend for natural gas to become the main energy source .

(1) Sichuan liquefied natural gas plant

The 300l/h natural gas liquefaction plant developed by Beijing Keyang Gas Liquefaction Technology Joint Company of Chinese Academy of Sciences and Keyang Cryogenic Equipment Company of Jianyang City, Sichuan Province, is a demonstration project of using LNG as industrial and civil gas peak balancing and gas instead of oil. The unit was completed in 1992 to provide LNG for LNG vehicle research.

The device makes full use of the pressure of natural gas itself, adopts gas turbine expansion mechanism to cool natural gas to liquefy, and is used for civil natural gas peak balancing or LNG production. The process flow is reasonable, and the gas turbine expansion machine is adopted, and the technology is relatively advanced. The device basically does not consume water and electricity, is an energy-saving project, but the liquefaction rate is very low, about 10%, which is consistent with its design principle.

(2) Jilin Oilfield liquefied natural gas installation

The 500l/h skid mounted industrial test device jointly developed by Jilin Oilfield, China National Petroleum Corporation and the Low temperature Center of the Chinese Academy of Sciences was successfully tested in December 1996. The device adopts the expansion machine cycle process with nitrogen as the refrigerant. The whole device consists of 10 skid blocks and all the equipment is made in China.

The device adopts gas bearing turbine expansion machine. Domestic molecular sieve deep removal of water and CO2 in natural gas, the process is simple, the use of skid-mounted structure, in line with the characteristics of small devices. Using pure nitrogen as refrigerant, the power consumption is higher than that of the expander cycle using refrigerant. The natural gas is liquefied at medium pressure (about 5.0MPa) without making full use of its own pressure (liquefaction at higher pressure can both increase the refrigeration temperature of nitrogen and reduce the refrigeration load), so the device has a large power consumption.

(2) Shaanxi North Gas Field liquefied natural gas

The 2×104m3/d "Shanbei Gas Field LNG Demonstration Project", which was completed and put into operation in January 1999, is a pilot project for the development of China's LNG industry and the first small LNG industrialization plant in China. The equipment adopts natural gas expansion refrigeration cycle, low temperature methanol washing and molecular sieve drying to purify raw gas, gas wave refrigerator and turbine expansion machine to perform low temperature refrigeration, gas engine as the power source of circulating compressor, and gas engine tail gas as the heat source of heating molecular sieve re-gas. The equipment is all made in China. The successful operation of the plant provides experience for China to produce LNG from natural gas in remote oil and gas fields.