A Simulation Study Of Using Low-Grade Waste Heat To Save Electricity Consuption In Compression Type Refrigeration Plant

Every country all over the world face the short of energy source,the economy of our country develop in high speed, and higher primary energy rate is indispensable. In allusion to the object of using energy, all kinds of technology for energy saving are studying and the measure of saving energy has very important significance.This paper study a technology of using low-grade waste heat to save high-grade electricity consumption in a chemical plant. On the one hand the plant requires low temperature cooled liquid from refrigeration station for playing down the temperature of industrial material, on the other hand the plant give birth to abundant low-grade waste heat.The scheme for saving energy is to employ a cascaded refrigeration system which consists of a waste-heat powered chiller and an electrically powered chiller. Namely in hot and humid seasons the waste-heat powered chiller shall work in order to offer lower cooling water to the electrically powered chiller.And the electrically powered chiller should work in high efficiency and save electricity consumptionModels of a typical screw type chiller and a cooling tower were built, combining the weather parameter of the plants seat, simulations of the original refrigeration system and the cascaded system were carried out for analyzing invest callback and saving power and reducing the green house gas let and corf of using.When the chiller of refrigerating capacity is 1213 kW,and the outlet temperature of cooled liquid is -6.5℃,the inlet temperature of cooling water is 15℃in the period from April 1 to November 30,it is concluded that the saving electricity consumption of the cascaded refrigeration system is 0.27 million kWh, the proportion of saving the electricity consumption is 22%, reduce 129.3T per year with the emission of greenhouse gas such as CO2 and reduce 60.7T per year with the use of standard coal. the expense of the system invest can reclaim the cost in 9 years.When the outlet temperature of cooled liquid of spot chiller is 0℃and the hot seasons the area is very long,the potential of saving energy and reducing the pollution of thecascaded refrigeration system is prominent.