Technology Study On Optimizing Operation Parameters Of Natural Gas Shallow Condensing Unit

There are 10 sets of natural gas shallow condensing unit in Natural Gas Company of Daqing OilfieldCo., LTD., all of which adopt Ammonia Compression Refrigeration Process. Most of these units were putinto operation in 1980s and all of them were designed in1970s, which become backward and have someunreasonable aspects. The problems, such as irrational temperature difference matching between watercooler and the units before and after it, unmatched operation parameters of the units, unreasonable use ofcycling water, inefficient recovery of waste heat and cold and mismatching of refrigeration machines andother systems, occur in these units after many years in operation.After the analysis on running status and the comparison of existing problems, this subject takesZhongqi Shallow Condensing Unit as investigated object. After 4 times' collecting information on site, theprocess flow, typical operation conditions in different seasons, calibration data of unit, performanceparameters of equipment are obtained and the problems existing in the unit including decline inrefrigeration capacity and low recovery rate of light hydrocarbons are known. The contents and direction ofthe study were determined after the analysis and calculation on the operation parameters in this factorywith thermal kinetic analysis of refrigeration system, process system energy conservation analysis andsimulation software of PRO/Ⅱ. To reach the aim of getting maximal benefit with least consumption ofpublic engineering, optimizing operation parameters and constraint conditions of calculation were donewith optimum theory. After that, an optimum design and optimized scheme were finished and a factoryrevamping and its evaluation were followed.The optimizing and revamping were finished on Zhongqi Shallow Condensing Unit in August, 2006,which processes natural gas of 30×10~4Nm~3/d. After evaluation on spot, the optimizing in Zhongqi ShallowCondensing Unit receives satisfactory results: condensation temperature dropping from -20.2℃to -28.5℃,light hydrocarbons yield increasing 2800t, the natural gas yield decreasing 120×10~4m~3, water conservation68×10~4t, and electricity conservation 53.5×10~4kwh per annum, which could get 389.5×10~4 yuan per annumafter converting into economy profit.