The Study On Regulation Characteristics Of Loop Seal In CFB Boiler

The circulating fluidized bed (CFB) combustion technology is one of the mostimportant clean coal combustion technology, and it is developing rapidly in China forthese years.Loop seal is currently the most widely used solid feedback unit incommercial circulating fluidized bed boiler. Due to reasons of commercialconfidentiality, there is not a lot paper on the characteristics of the Loop seal. Loopseal in the regulating characteristics determine the entire boiler solid circulation feedback, thereby affecting the bed temperature in the furnace, combustion anddesulfurization state.Firstly, the theoretical analysis of the theoretical analysis of the various parts ofthe entire back of the loop seal feeding system, and put forward the material themethod of calculation of height h, and improve the theoretical Loop seal in theory tosolve the model. The subsequent two-fluid model of this article with the entireU-shaped valve, numerical simulation, and simulation software for the first time touse the UDF. This will greatly facilitate the numerical simulation of the entirecirculation loop. Finally, this paper, experimental methods to study the regulationcharacteristics of the U-shaped valve, and compared to the results obtained in theexperiment and numerical simulation results. Experimental method to verify theaccuracy of the numerical simulation.By these three research methods, We can get regulation characteristics.Specifically, in the other word,The relationship between the Loop seal in thecirculating feed back six influencing factors. These six factors are the the flow ofwind in Loop seal, loose wind, the height of the horizontal channel, the overflowheight, material high and the bottom of the furnace fluidized wind. These six FactorsAffecting results were:(1) With the increase of the fluidizing air, the loop feed back increases. But the growthrate is getting smaller and smaller, the return valve when the flow of air increases to acertain extent, into the channeling wind condition, feed back loop starts to decrease.(2) The velocity of loose wind is generally small, loose wind loop feed back with loose wind increases, increase. Loose too much wind, and easy return valve into thechanneling wind conditions.(3) the horizontal passage height increases, recycled back to the feeding amount of theadjustment range will change. Meanwhile, the loop feed back adjust the amplitudebecomes large. On the contrary, the amplitude of accommodation decreases.(4) overflow height ringing the range of normal operating conditions, flow of windvelocity and range loop feed back, the higher the altitude, the greater the windvelocity of the stream, the smaller the loop feed back.(5) The expected high h Loop seal in running state of one of the bases. When h is verysmall, the particles return valve may be in a state of the moving bed. h is very large,the return valve may be in channeling wind conditions. Normal operating conditions,h is a range. Feed high in the U-shaped valve is in stable condition with negativefeedback. Due to the existence of this effect, the U-type return valve has thecharacteristics of self-balancing. Under normal operating conditions, high material thehigher the better self-balancing features.(6) the bottom of the furnace fluidizing air velocity (u0) Although not a U-shapedvalve itself a feature of, but in a different under the fluidizing air at the bottom, theentire cycle pressure loop is different. The u0affect the U-shaped valve affect theentire pressure loop imports and exports out of the pressure and the riser material,feed back to affect the circulation Gs. When the bottom of the furnace fluidizing airvelocity increases, Gs increases, otherwise reduced.