| With the increasing attention of the state to environmental protection,some provinces and municipalities have listed smoke control as an indicator of atmospheric environmental management.At present,there are three main technical routes for plume control: flue gas condensation,flue gas heating and flue gas condensation and reheating.The flue gas heating methods mainly include GGH(Gas-Gas Heater)and MGGH(Media Gas Gas Heater).There are some ways of flue gas condensation,such as slurry cooling,flue gas cooler and spray tower cooling.The condensation method of spray tower has the advantages of synergistic elimination of some pollutants,large cooling range and good flue gas treatment effect.MGGH has the advantages of low leakage rate,wide adjustment range and flexible arrangement.After comprehensive comparison,the combination of spray tower and MGGH is more recommended when the comprehensive conditions permit.In the latter part of this paper,the spray tower is taken as the research object.Combining with the basic operating parameters of a 320 MW unit in Datang,a large number of empirical documents about spray tower design are consulted,and the geometric dimensions of spray tower are preliminarily designed.Then the optimum diameter-height ratio and flue gas inlet angle are determined by CFD numerical simulation.The non-uniform distribution of internal flow field is optimized.Among them,the numerical calculation of internal flow field of spray tower is mainly based on standard DPM model.The conclusion has certain reference and guiding significance for the design and optimization of spray tower.The conclusions are as follows: 1)For the spray tower with the same side inlet and outlet,the diameter-height ratio is about 0.550,the flue gas inlet angle is about 15 degrees,and the internal flow field uniformity of the spray tower is relatively good.Before installing the optimization plate,the distribution of empty tower streamline is not uniform,spraying has a certain integration effect on flue gas,pressure drop resistance mainly comes from spraying;2)the installation height of the optimization plate has a certain effect on spraying.The internal flow field of the spray tower has a great influence,which mainly affects the size and distribution of swirling flow in the spray tower and optimizes the overall velocity direction of flue gas in the upper part of the spray tower.The low or high installation height of the optimization plate is not conducive to the uniform distribution of the flow field in the spray tower.For the spray tower model of this size and form,it is suggested that the optimum plate be installed at about 6.25 m.3)The hole ratio of the optimum plate has a great influence on the flow field and velocity gradient distribution in the spray tower,which mainly affects the location and velocity distribution uniformity of the swirl.High or low opening rate is not conducive to the uniform distribution of internal flow field.The smaller the opening rate,the greater the resistance of flue gas through.From the streamline uniformity,the optimum plate opening rate is 32.12%.4)When the optimum plate opening rate is 32.12%,the diameter parameters of the optimum plate opening have little effect on the streamline uniformity distribution in the spray tower,but the hole diameter has a great influence on the flue gas velocity distribution.Reducing the aperture in a certain range is more conducive to optimizing the uniform distribution of flue gas velocity above the board.The smaller the pore size is,the smaller the pressure drop of flue gas is.The conclusions are as follows: 1)For the spray tower with the same side inlet and outlet,the diameter-height ratio is about 0.550,the flue gas inlet angle is about 15 degrees,and the internal flow field uniformity of the spray tower is relatively good.Before installing the optimization plate,the distribution of empty tower streamline is not uniform,spraying has a certain integration effect on flue gas,pressure drop resistance mainly comes from spraying;2)the installation height of the optimization plate has a certain effect on spraying.The internal flow field of the spray tower has a great influence,which mainly affects the size and distribution of swirling flow in the spray tower and optimizes the overall velocity direction of flue gas in the upper part of the spray tower.The low or high installation height of the optimization plate is not conducive to the uniform distribution of the flow field in the spray tower.For the spray tower model of this size and form,it is suggested that the optimum plate be installed at about 6.25 m.3)The hole ratio of the optimum plate has a great influence on the flow field and velocity gradient distribution in the spray tower,which mainly affects the location and velocity distribution uniformity of the swirl.High or low opening rate is not conducive to the uniform distribution of internal flow field.The smaller the opening rate,the greater the resistance of flue gas through.From the streamline uniformity,the optimum plate opening rate is 32.12%.4)When the optimum plate opening rate is 32.12%,the diameter parameters of the optimum plate opening have little effect on the streamline uniformity distribution in the spray tower,but the hole diameter has a great influence on the flue gas velocity distribution.Reducing the aperture in a certain range is more conducive to optimizing the uniform distribution of flue gas velocity above the board.The smaller the pore size is,the smaller the pressure drop of flue gas is. |
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