Research On The Application Of Waste Heat Recovery From Wastewater In Printing And Dyeing Enterprises

With the development of society and economy,the demand for energy by mankind is also increasing.Energy has become one of the most basic factors of human production and life.At the same time,most countries in the world are still facing the continuous destruction of the environment and increasing energy.Due to shortages,energy conservation,emission reduction,and environmental protection have become important development goals for my country and the world.Our country is the largest country in the textile printing and dyeing industry.It discharges at least 1 billion tons of printing and dyeing wastewater each year.The printing and dyeing wastewater contains a large amount of heat energy.If it is not used,it will cause waste of energy and environmental pollution.Heat pump technology is a technology that absorbs heat from low-grade heat sources and converts the work done by compressors into high-grade heat sources.It is currently developing rapidly in my country.This article is based on a printing and dyeing company in Zhejiang Province.Aiming at the company's characteristics of large printing and dyeing wastewater discharge,high wastewater discharge temperature,and failure to use it in time,heat pump technology is used to recycle the heat in the printing and dyeing wastewater and improve the energy utilization rate,And launched the following tasks:(1)The energy consumption of printing and dyeing enterprises was investigated and tested,and the relationship between the main energy consumption of the enterprise,water,electricity,and steam,was fitted with a polynomial,and related formulas were obtained.Analyze the main energy consumption of enterprises and various workshops,of which steam accounts for the largest proportion,at least 55.74%.The thermal energy contained in printing and dyeing wastewater can be used to heat production water and reduce the use of steam.(2)Test and analyze the wastewater discharge volume,wastewater discharge temperature and wastewater quality of printing and dyeing enterprises to meet the requirements of wastewater waste heat recovery system.In addition,the heat contained in the printing and dyeing wastewater can heat up 711 t of production water for the enterprise every day,saving46.3t of steam,heating 34,000 square meters in winter,and cooling 13,000 square meters in summer.(3)The form of the waste heat recovery system of printing and dyeing wastewater and the COP of the overall system are analyzed,and the form of the system is determined as: an indirect sewage source heat pump system with a preheating heat exchanger.According to the results of the analysis,two schemes of waste water heat extraction were selected,and the performance influencing factors of the two schemes were analyzed,and the optimal parameter scheme was obtained.And the exergy efficiency analysis of the scheme is 54.99%,and the equipment selection calculation of the scheme.(4)Analyze the economics of the project.From the static economic evaluation analysis,it is known that the recovery time of the project is short.From the dynamic economic evaluation analysis of the project's financial net present value,internal rate of return,and sensitivity,it is known that the project is economically feasible.,And has a certain degree of anti-risk ability.By comparing traditional coal-fired boilers and gas-fired boilers,the project is analyzed for energy saving and environmental protection.The project saves at least 1.284 million yuan in costs and 870 t of standard coal every year.