Performance Analysis And Optimization Of Low Temperature Drying System For Printing And Dyeing Sludge Based On Absorption Heat Pump

The treatment and disposal of printing and dyeing sludge has become the bottleneck of the sustainable development of the printing and dyeing textile industry.This thesis selects the absorption heat pump printing and dyeing sludge low-temperature drying system in an industrial park in Guangdong Province as the research object,and introduces the process principle of the system in detail.Experimental and simulation studies have been carried out on the matching of the operation parameters of the absorption heat pump and the drying module of printing and dyeing sludge during the operation of the system,and the optimal operation measures have been put forward.At the same time,the problems of crystallization and corrosion on the surface of the cooler of the drying module are optimized and analyzed,providing a reference for the improvement of the drying performance of the whole system.The thermodynamic analysis of the air cycle and the absorption heat pump cycle in the system is carried out,and the heat balance model of the system is established based on the field measured data.The results show that the COP_H of absorption heat pump is1.51,the environmental benefit factor is 4.64 kg _H2O/kg _CO2,the cost of sludge treatment per ton is 150.74 yuan,and the annual treatment cost saving is 2.4384 million yuan.The system have a good environmental and economic benefits.The physicochemical properties of the printing and dyeing sludge were tested and experimentally studied.The results showed that the p H of the sample was 6.0,slightly acidic.The initial moisture content is 81.34%,and the organic content after drying reaches65.96%,which calorific value accounts for 38.7%of the low calorific value of standard coal and can be used for secondary use.When the air supply temperature is set at 65℃-75℃,the air supply humidity is set at 20%-25%,and the sludge thickness is set at 40mm in the low-temperature drying process,the sludge drying rate is high and the effect is good.The crystallization and corrosion of the cooler surface are optimized and analyzed in combination with the printing and dyeing process and wastewater treatment process.For the crystallization phenomenon,it is recommended that the front-end water treatment process give priority to the use of alkaline conditioner,shorten the sludge retention time,appropriately reduce the air supply temperature（2-3℃）,and increase the cold water temperature（3-4℃）,so as to slow down the formation of sulfur crystals.For the corrosion phenomenon,it is recommended to use the nanometer coating with acid resistance environment for corrosion prevention.The system performance is simulated and optimized by Aspen Plus software based on the test and experimental results.The results show that the system performance can be optimized by reducing the supply air temperature by 2℃-3℃,the supply air humidity by2%-3%,and the cold water temperature by3℃-4℃on the basis of the original operation status.The COP_H of absorption heat pump is increased by 5.58%,the environmental benefit factor is increased by 6.09%,the cost of sludge treatment per ton is reduced by5.46%,and the annual saved treatment cost increased by 9.58% after optimization.