The Design And Analysis Of Wastewater Heat Utiliaztion System For A Printing And Dyeing Enterprise In Zhejiang

Printingand dyeing industry is high-energy consuming and everyday it willproduce a lot of wastewater which has high temperature. A lot of hot water is preparedfor production by dyeing and printing industry consuming much energy which carriesa lot heat after dyeing and printing.Discharging the water directly without recyclingisa huge waste of waste water heat, the current situation of dyeing and printingindustry high-energy consuming will do not change. Domestic and foreign scholarshave done a lot of empirical research on waste water heat recovery and heat pumptechnology for waste water heat recovery has been used in city waste water heatrecovery, but living examples of heat recovery for waste water produced by dyeingand printing industry are not always seen and some projects realize waste water heatrecovery simply using heat-exchanger or heat pump which do not design the heatrecovery project based on enterprise specific situation.Just under such a background the paper analyses the enterprise energyconsuming and structure of energy consuming and makes a conclusion that energyconsuming for dyeing accounts for46.28%of enterprise energy consuming amongwhich about35%is steam accounting for87.7%of dyeing energy consuming throughdata of investigation. The research measured the temperature of waste water and watervolume and got the temperature and water volume for heat recovery. Analysis of heatrecovery potential on enterprise dyeing and printing waste water shows it can save61.3t steam during off season and95.5t steam during season.In this paper, the traditional waste heat recovery system has beenimproved,designed a waste heat recovery system to meet the production demands ofhot water. To raise the water temperature to6℃0,the heat recoveryscheme isdesigned topreheat use the heat exchanger and then reheat use the heat pump unit.Toreduce corrosion of heat pump from printing and dyeing wastewater,the evaporator side of waste-water source heat pump use water source heat pump water cyclescheme.Avoiding the problem of declining performance of the unit which causedbydirect heat exchange with the heat pump unit and wastewater.Condenser sideuse acombination of heat exchanger and heat pump unitstemperature upgrade scheme.Thesystem can produce800tons60℃hot water a day, the hot water can instead of roomtemperature water into the steam heat exchanger,prepare hot water ofproduction. Theinitial investment of this system is1.425million yuan,compared with the originalsteam heat system enterprises, the annual savings is351,000yuan, the payback periodis about four years,Use estimation of NPV,the net income over the next decade is732,000yuan,and converted into the reduction emissions of pollutants for theenterprise.Analysis shows that this waste-water heat recovery system has higheconomic and environmental benefits.