A Study On The Optimization Of Cryogenic Parameters And The Measures To Improve The Yield Of Natural Gas

As an important clean energy,natural gas is widely used in the world,and plays an important role.Around the processing of natural gas at home and abroad,a supporting treatment process has been formed.Recovery of light hydrocarbon and purification of natural gas will improve economic and social benefits.According to the analysis of gas gathering capacity and existing unit scale in the southern area of Daqing Oilfield,in September 2010,a cryogenic unit of Nanba was designed and built by Daqing Oilfield Engineering Co.,Ltd.The deep cooling process of feed gas pressurization plus molecular sieve deep dehydration,expander and propane auxiliary refrigerant refrigeration is adopted in Nanba cryogenic unit.The device is equipped with a centrifugal feed gas compressor unit,a propane refrigeration unit and an expansion refrigeration unit,in which the expansion agent is the main refrigeration equipment and the propane machine is the auxiliary refrigeration equipment.In this paper,combined with the actual situation of south eight cryogenic in-depth investigation and analysis,according to the design parameters and actual running status,to deal with moisture,transmission of products,such as gas and light hydrocarbon,calculated the whole material of demethanizer,heat exchange equipment（cold box,air cooler）,equipment（such as propane,expansion machine）for accounting,evaluation system and equipment running effect.By aiming at the problems existing in the plant,such as higher CO₂ content in the raw gas component,lower negative temperature yield of refrigeration than the design value,and lower load of propane machine,corrective measures are proposed.PRO/II simulation software was used to simulate and optimize the process of the Nanba cryogenic equipment,analyze and evaluate the factors affecting product yield,system and energy consumption of individual equipment,diagnose the unreasonable links in the operation of the equipment,propose optimization and improvement measures,optimize the capacity of the equipment,and improve the product yield.According to the energy consumption of the unit,the factors affecting the power consumption of compressor and propane machine were studied.By carrying out this research,we will deeply investigate and analyze the operation status of the device,find out the difference between the actual operation and the original design conditions,analyze and evaluate the relevant factors affecting the product yield,system and single equipment energy consumption,find out the unreasonable links of the device,and point out the problems for the optimization of the device.It provides scientific basis for parameter adjustment,production increase and consumption reduction,as well as data support for production management and post operation.Improve light hydrocarbon yield,save production cost and optimize energy consumption of the unit.