Study Of Numerical Simulation On Elbow-type Pulverized Coal Concentrator

By the development of society and electric power industry, generator unit is developing to large scale. 300MW and 600MW generator units have become the mainstream. The change of people's demand for electricty increase the peak-valley difference of electric network load. The large-scale units popularly have to take the task of peak-load regulating. The problems of highly efficient combustion and steady combustion in low load are urgent to be solved. The dense-dilute combustion technology is an excellent combustion technology , which can realize steady combustion with high efficiency, prevent slagging and reduce the emission of contaminatioin. Developing new-type dense-dilute pulverized coal burner is one of hotspots in pulverized coal combustion realm.This paper analyzes the mechanism of dense-dilute combustion technology, points out the proper way to utilize dense-dilute combustion: the thickness of pulverized coal should can be ajusted according to the change of coal and boiler load; enhance heat circumfluence and turbulent perturbation to found a steady igniting area; strengthen the blend of pulverized coal and air in the combustion anaphase to insure the combustion efficiency. Then then this paper analyzes several prevalent dense-dilute burners.This paper introduces and analyzes main gas-solid two phase models , introduces the mechanism of CFD and PHOENICS-a kind of CFD software by which the gas-solid fluid is simulated, then introduces the use of PHOENICS and the simulation method of gas-solid fluid in pulverized coal concentrator.According to the problems in retrofits of dense-dilute burners in our country, the thought combining elbow with louver concentrator is brought forward. By PHOENICS3.2, the gas-solid two phase fluid of three types of concentrators is simulated.1) Simulate the gas-solid two phase fluid of single elbow and calculate the concentrating performance indexes. This paper researches the concentrating effect of elbow and blending speciality in horizontal segment behind elbow, and then analyzes it's concentrating performance.2) Wholly simulate the gas-solid two phase fluid and calculate the concentratingperformance indexes of both elbow and louver disposed in horizontal segment behind elbow. This paper analyzes the influence of elbow on the concentrating performance of louver concentrators and researches the working state of louver concentrators behind elbow.3) Simulate the gas-solid two phase fluid for louver-in-elbow type concentrator and calculate the concentrating performance indexes. This paper simulate for concentrators with different structures by changing their structures such as numbers of vanes, angles of vanes, position of vanes and installing baffle or not etc, qualitatively analyzes the effect of different structures on the concentrating performance, and appraises the performance of this kind of concentrator by comparision with former two type of concentrators.