Large rectangular flue pipes installed in coal-fired power plants usually need inner supports to ensure their stability. The design and arrangement of inner supports in rectangular flue pipe before electrostatic precipitator have an impact on precipitators effectiveness and lifespan. Currently, there are two schemes used for setting inner supports in China. One is National Standard Specification (NSS) and the other is an American Combustion Engineering company design criterion (CE). No work has been done on the comparison of these two types of inner supports, especially with consideration of ash deposition. In this paper, the effect of ash deposition on pressure drop and velocity distribution in practical production are carried out, which are adopted flue pipes volume 1/8 and 1/16 as the ash layer. The numerical results show that the ash deposition volume have effect on pressure loss of the straight flue pipes. However, the effect depends on the inner supports type.
Large rectangular gas ducts installed in power plants usually need inner supports to ensure their stability. Generally two schemes are used for setting inner supports. One is National Standard Specification (NSS) and the other is an American Combustion Engineering company design criterion (CE). The design level of inner supports in flue pipe has a great effect on flow distribution. In this paper, three kinds of inner supports which are common in power plants are simulated by using computational fluid dynamics (CFD). Through a comprehensive analysis of their flow fields and pressure, it can be concluded that NSS inner supports which are thinner, vertical to each other and have more rows is the best design scheme among these three kinds of inner supports.
The flow distribution in flue pipes has a great effect on collection efficiency.Gas pressure and velocity distribution in flue pipes upstream electrostatic precipitator were investigated using computational fluid dynamics (CFD) in this paper. The flue pipe model was established on the basis of standard straight and bended flue pipe which were widely used in engineering. And the availability of numerical simulation model was verified by comparing the empirical curve and the numerical simulation results of a common pipe bend without inner supports. In the same condition, these two flue pipes were simulated. The result shows that inner supports have great impact on flue pipe and the values of the pressure drops are closely linked to airflow directions. These results can provide theoretical basis and method guidance for design of inner support.
At present, power industry is still dominated by coal-fired power generation in China. Coal ash is a major source of air pollution. An important way for controlling atmospheric pollution is reducing dust emission concentration in the coal-fired power plant. Standard curved pipes and guide plates which are widely used in practical application are simulated using computational fluid dynamics (CFD) in this paper. The result shows that inner supports have great impact on flue pipes. Successive bend with guide plates do not have a better flow distribution. These results can provide theoretical basis and method guidance for the design of inner supports.
The gas flow status including velocity and pressure in the rectangular gas duct (before or after) electrostatic precipitator of a power plant were simulated using Fluent software. The grid accuracy which is required by simulation has been determined then the gas flow status has been analyzed through the comparison between numerical simulation results and empirical calculation results. The results show that flues inner supporting structures are the main factor of gas pressure drops and outlet velocity distrubution.
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