Abstract
As a kind of clean and high quality fuel, natural gas has attracted more and more attention. With the global environmental problems becoming increasingly serious, reducing the use of oil and coal and other energy sources is becoming the key to adjusting national energy structure. It is China's major energy use policy to accelerate the use of wind energy, nuclear energy, solar energy, natural gas and other clean energy. The transportation of natural gas mainly depends on pipeline transportation, which greatly limits the development of natural gas. Due to its small volume and convenient transportation, Liquefied natural gas (LNG) can fully make up for the shortage of natural gas pipeline. After being liquefied, the volume of the natural gas can be reduced by 600 times. LNG can play a good role both in large-scale transportation on the sea and in land natural gas pipeline. Distributed control system has been gradually applied in various fields of industry. At present, it has become the mainstream of industrial automatic control system. Now, the new liquefied natural gas chemical factories are all equipped with a distributed control system. However, the basic control system cannot meet the needs of urban natural gas operators for liquefied natural gas production. With the expansion of the liquefied natural gas market, the city's natural gas operators have also established their own natural gas liquefaction factory in natural gas station. However, because the natural gas pressure on the inlet and outlet of the LNG factories changes with the fluctuation of the city gas load, the distributed control system cannot automatically adjust the production condition according to the pressure fluctuation. In order to solve this problem, this paper studies the natural gas liquefaction factories based on urban natural gas operators. Firstly, the distributed control system is studied. Secondly, it focuses on the application and principle of liquefied natural gas. Finally, according to the characteristics of urban gas, the DCS is improved so that it can meet the demand of liquefied natural gas production. After improvement, the production efficiency of LNG production factories is greatly increased, and its fault rate of operation is reduced. Besides, the whole process becomes more stable and safe.
