Inverstigation On Cold Energy Recovery Technique For Liquid Nitrogen Vaporization In Air Separation Unit

In recent years, the state advocates "energy conservation and emissions reduction" and lowcarbon life is coming. Due to the irreversible energy utilization, the state and society is payingmore and more attention to the efficient use of energy and the sustainable development of thesociety.In air separation industry, in order to reduce the saturated vapor content and the heat flux ofthe main heat exchanger, it is required that the temperature of the air into the heat exchangerand the distillation device should be reduced as much as possible. The amount of the coldenergy consumption is accounted to be15%of the entire device of low pressure system.Generally, a single refrigerator (model:30HXC165AH, nominal refrigerating capacity10000kCal/h) and water pumps consumpt about28000KWH electric power; At the same time,empty bath carburetor (liquid nitrogen, liquid oxygen, liquid argon, liquid carbon dioxide) forliquid vaporization, in which heat should be transfred from the air, contains a lot of coldenergy which was totally wasted so that the cold recycling is particularly important.With the development of industrial technologies, there put forward higher request to theprocessing capability of air separation system. The gasification device of air separationindustry is becoming larger,80000Nm3/h air separation unit has been put into production.According to the incomplete statistics, only Linde-Gas gasification device in South China areahas more than30sets, and constantly build market rate more than7%a year on average.In this paper, the present situation of the air precooling system in air separation industry ismainly introduced and the development of alternative energy saving technology of airseparation unit is analyzed. Based on a Spectra30000air separation system in Linde(Shenzhen) co., LTD., Guangzhou Iron and Steel Group Corporation, A new technique wasput forward by comparing the process characteristics of the empty bath carburetor (liquidnitrogen, liquid oxygen, liquid argon, liquid carbon dioxide) and the air precooling system, inwhich the cold air bath carburetor was used as the cold source of air separation unitprecooling system to reduce air temperature of the pretreatment processing plan as much aspossible. Research results show that the scheme can replace a30HXY Screw Water Chiller inoriginal precooling system and the refrigerating capacity meets the demand of air separationprocess, which saves the operating cost of634550yuan/year and has good social andeconomic benefits.