Study On Demisting Characteristic Of The Mist Eliminator For Fume Dehydration

The thermal power industry is one of the industries with the largest industrial water consumption.Its amount of water withdrawals is about 40%of the national industrial water withdrawals.Under the background of water shortage and policy tightening,resource shortage in northwest China and high cost of seawater desalination in southeast China largely limit the construction and development of thermal power plants.However,coal contain a lot of water.The water discharge is about 200 t/h in a 600 MW unit,and million tons of water issues from the chimney in a year.So recycling waste water from fume has an important significance in dealing with water shortage and reducing the cost of water of thermal power plants.In order to solve the problem of efficient removal of condensing superfine droplets in the key technology of flue gas dehydration,a kind of mist eliminator with shutter was put forward in this paper.Using numerical simulation method,it compared and analyzed the different defrosting performance of the mist eliminator,the common demister and the hook plate demister under different conditions,and designed the corresponding dehydration system to calculate and analyze the economy of the three kinds of eliminators.First,using numerical simulation,the flow field distribution and demisting characteristics of three demisters were obtained,and the difference between the mist removal efficiency and the resistance characteristics of the mist eliminator and the other eliminations under the different fume velocity and droplet size was analyzed.The result suggested that the conventional eliminator cannot eliminate droplet with 15 ?m.Accompanied by system resistance rising(the maximum up to 837 Pa),eliminator with hamulus could highly increase demisting efficiency,but it also could not eliminate 5?m tiny droplet.Adopting mist eliminator with shutter could be very good to deal with the bad performance of tiny droplet demisting,especially in low fume velocity,which can highly increase demisting efficiency with less extra resistance(reduce about 35%).Then through the simulation of mist eliminators in different structure parameters,the effects of blade space,bending angle,bending length,hamulus width,shutter width,space,and position on demisting efficiency and system resistance were analyzed.The optimal structure parameters were found.On the basis of numerical simulation results,the test platform of fume dehydration system was designed.The actual operating data was added to economic theoretical calculation of three dimisters.The related economic models were established,from benefits and costs.Lastly,net income,ROI,and IRR were chosen as economic evaluation indicators.The results showed that the eliminator with shutter was significantly ahead of other two mist eliminators in all kinds of economic indicators.When the flow rate of flue gas was 10 m/s,the maximum net profit was 264 thousand yuan per year,ROI was 0.19,and IRR was 62.3%.