Removal Technology And Application Of Heavy Hydrocarbon Components In Feed Gas Of Guang'an LNG Plant

Although the heavy hydrocarbon component above Cs+accounts for a small proportion in natural gas,it will result in the heat exchanger flow passage blocked in the liquefied low temperature section if it is not completely removed in the natural gas liquefaction process.It also will cause the liquefaction rate reducing and the energy increasing.The severely blocked can cause the device stop working.Based on the freeze-blocking phenomenon of cold box in Guangan-1 million square LNG plant,this paper conducts a series of basic research on its heavy hydrocarbon removal technology,and provides theoretical basis and technical support for deep purification of LNG in Guang'an LNG plant.This study mainly combines the gas source sampling analysis data and theoretical research results in the production process of Guang'an LNG to determine the heavy hydrocarbon components causing blockage of the LNG plant;the GPA vapor/liquid/solid balance software is used to calculate the freezing concentration at different temperatures.And propose to remove the heavy hydrocarbons which are difficult to separate in natural gas.The experimental and theoretical comparisons are carried out to find a suitable adsorbent,and the adsorption and regeneration conditions of the process are studied..The main research contents of this thesis are as follows:(1)Heavy hydrocarbon components such as benzene and cyclohexane are the main reason to cause the low temperature clogging of LNG plants;(2)The freezing concentration of heavy hydrocarbon components such as benzene and cyclohexane at different temperatures was calculated by GPA vapor/liquid/solid equilibrium software;(3)Defining the judgment basis of low temperature blockage caused by components such as benzene and cyclohexane;(4)The adsorption and regeneration conditions of carbon to remove benzene,cyclohexane and other clogging heavy hydrocarbon+molecular sieve dehydration combined process were studied;(5)Formed a complete process simulation of the activated carbon easy-occlusion component+molecular sieve adsorption dehydration,and optimized the operating conditions and application scope by engineering accumulation.After adopting this technology,Guang'an LNG plant solved the problem of low temperature blockage in cold box,reduced the number of device stop,made the device safe and stable production,saved operating costs,and achieved a good example of the operation of similar devices in China.It proves that the project is practical and effective.When the composition of the raw material gas changes,it can meet the adaptability of the LNG plant cold box to heavy hydrocarbons,save the time for the plant to start production,and create good economic benefits for the enterprise.