Design And Analysis Of Reheating Furnace Flue Gas Carbon Capture System Based On The Sensible Heat Of Continuous Casting Slabs

In recent years,CO₂ emissions have increased year by year,and the resulting climate change issues,such as the greenhouse effect,have attracted widespread attention.Corresponding CO₂ emission reduction technologies have also been extensively studied.At present,carbon capture and storage（CCS）technology is one of the most effective ways to shorten CO₂ emission in the short term.It has the advantages of good capture efficiency and high purity of CO₂ recovery.CCS technology has been deeply studied in power plants,but research on CCS in steel companies is rare.As the pillar enterprises in the process of industrialization in China,the high energy consumption and high CO₂ emissions status of iron and steel enterprises can not be ignored.Therefore,it is of great significance to carry out carbon capture technology research for steel plants.In the view of the difference between the iron and steel enterprises and the power plant,this paper designs a set of carbon capture system for the flus gas of the reheating furnace based on the sensible heat of the continuous casting slabs.The waste heat of the steel rolling plant is used rationally to achieve CO₂ capture of the flue gas.Firstly,this paper analyzes the CO₂ emissions of various processes in iron and steel enterprises and the parameters of flue gas discharged from each process.According to the analysis of production conditions and other factors,the heating furnace flue gas from the rolling mill is one of the most suitable processes for carbon capture.Based on the composition of the furnace flue gas and the advantages and disadvantages of various carbon capture methods,the monoethanolamine chemical absorption method was selected as the carbon capture method of the furnace exhaust gas.Due to the large number of steel slabs which should be cooled in the steel rolling plant,a lot of heat is wasted during the cooling process.This paper collects this part of the wasted waste heat from the continuous casting slabs,providing heat for the carbon capture system,and making full use of the abundant waste heat resources of the steel companies.By using the commercial software Aspen Plus to simulate and optimize the parameters of regeneration pressure,reflux ratio,regeneration energy consumption and CO₂ loading in lean solvent,the relationship of main parameters and renewable energy consumption are obtained.The results are compared with the power plant and the accuracy of the results are verified by other carbon capture articles.Results show that when the regeneration pressure increases,the recovery rate of CO₂ increases,and the reboiler heat load of per unit of capture volume decreases.However,increasing the regeneration pressure also increases the energy consumption of the pump.The minimum heat load of the reboiler is basically a fixed value under the condition that the flow rate of the lean liquid and the capture rate are fixed.When the capture rate is fixed,CO₂ loading in lean solvent increases and the flow rate of lean solvent increases.When the CO₂ loading in lean solvent increases,the reboiler heat load decreases first and then increases.The results show that the CO₂ capture rate is 90.01%,the CO₂ purity is 98.4%,the annual capture capacity is about 70,000 tons,the reboiler heat load is8.19 MW,and the CO₂ heat load of unit mass was 3.67 MJ/kg CO₂.Compared with conventional power plants and NGCC power plants,the accuracy and rationality of the simulation results are proved.Secondly,this paper also calculates the heating capacity of the heating system,including the heating capacity of the steel billets and the main parameters of the heat recovery boiler.It has been calculated that the combined method of slabs and the heat recovery boiler can provide heat of8.5 MW for the reboiler in carbon capture system,demonstrating the feasibility of utlizating the waste heat of slabs to provide heat for the reboiler in the system.In addition,this paper also calculats the additional CO₂ emissions by supplemental combustion equipment of the heat recovery boiler.When the waste heat of the slabs is not enough,the additional CO₂emission was only 26.5%of the captured amount.This demonstrates that the supplemental combustion equipment can not only ensure the stable operation of the system,but also do not discharge excessive CO₂.This method plays an exemplary role in the establishment of carbon capture systems for steel plants.