Condensing Coal-fired Flue Gas Reheat System And Performance Research

At present,China USES 1.5 billion tons of coal in coal-fired power plants every year,accounting for half of the country's total annual coal consumption.Therefore,research on FGD in coal-fired power plants is very important.Limestone-gypsum wet flue gas desulfurization process is used in most coal-fired power plants in China.The main components of the flue gas after wet desulfurization are N₂,CO₂,O₂,H₂O,etc.In addition,the flue gas also carries heavy metals such as SO₂,SO₃,NO_X,Ca SO₄,Cl^-,F^-,Hg,Pb and solid particles,among which water vapor occupies a high proportion.The flue gas vapor at the exit of the desulfurization tower is generally in a saturated state.If it is directly discharged into the atmosphere,it will form a"white smoke"phenomenon.When the flue gas is discharged into the atmosphere,the flue gas is always in an unsaturated state,so there is no condensation of water vapor in the flue gas,thus there is no"white smoke"phenomenon.Aiming at this design idea,this paper designs a deep treatment system for white flue gas by analyzing and studying the principle of generation and elimination of white flue gas.The research results show that when the flue gas in the chimney exit temperature of 50?,the need to reduce and the most dramatically raise the temperature of 30?,relative humidity was 60%,the adoption of flue gas condensation in reheating technology,under the condition of flue gas can be in the minimum temperature of-12.9?environment to achieve the purpose of white smoke elimination,which is the most widely applicable scope,applicable scope and flue gas heating technology is minimal.So the chosen process route is flue gas condensation and reheating technology.In order to eliminate the white visual pollution of flue gas,the design and performance of flue gas cooler,flue gas reheater,flue gas condenser and chimney are studied in this paper.The results show that the acceleration of the water in the tube cannot effectively improve the heat transfer performance of the heat exchanger,and the wind speed in the heat exchanger cannot be too high because the wind speed of the tube bundle is not conducive to heat transfer due to the high wind speed.In addition,by giving full play to the advantages of small diameter,thin tube wall fluoroplastic heat exchange tube with good toughness,plasticity and mechanical properties,the heat exchange area of unit volume heat exchanger can be increased,thus greatly improving the heat exchange coefficient of heat exchanger and improving the heat exchange efficiency of heat exchanger.Compared with the traditional metal heat exchanger,the fluoroplastic heat exchanger has the characteristics of simple structure,convenient cleaning,not easy scaling and high heat exchange efficiency,thus improving the economic benefit of the system.In order to prove this point,the MGGH system of fluoroplastic heat exchanger was studied experimentally by simulating flue gas cooler and flue gas reheater.The results show that the heat transfer coefficient of the flue gas cooler is larger than that of the flue gas reheater under the same conditions,so the heat transfer area of the flue gas cooler can be designed to be larger,which is beneficial to significantly improve the heat transfer efficiency of the heat exchanger.Because of the significant non-stick characteristics of fluoroplastic heat exchanger,it is better to use spray water to clean it under normal circumstances,which is beneficial to solve the problem of fouling and blockage of flue gas heat exchanger?GGH?.