| In recent years,gas industry has developed rapidly,especially in the context of major energy conversion projects in Shandong Province,more and more cities and regions use natural gas.Most of the strong-drum gas water heaters adopt partial premixed combustion.Several rows of atmospheric burners are juxtaposed in the closed combustion chamber,and centralized air supply is provided by blowers.This brings many problems,such as uneven distribution of air and unreasonable air intake direction,uneven distribution of gas flow and methane concentration in the fire,vortex and turbulence of secondary air flow,and unsmooth air flow and so on.Firstly,according to the actual size of the strong drum gas water heater,the geometric models of the blower,air distribution chamber,burner and secondary air passage are established.Mathematical models are established based on advanced fluid mechanics and advanced heat transfer.The air supply system of strong drum gas water heater is simulated by using CFD software.Secondly,the experimental system of strong-blower gas water heater is established,and the air volume of the blower with different speeds and the distribution of the primary air coefficient under different loads were tested.The experimental results are compared with the simulation results,which verifies the reliability of the numerical simulation method for studying the strong drum gas water heater.Then,the influence of primary air baffle opening area and location on primary air distribution and gas flow distribution at fire was studied by numerical simulation;the influence of gas distributor location on methane concentration at fire;the influence of gap between front side of gas distributor and front cover of combustion chamber on methane concentration distribution at fire;and the influence of secondary air baffle opening location on secondary air.The influence of flow has been optimized and improved.Finally,the distribution of flame height and the variation of flame height at the fire under different loads were tested by using a strong drum gas water heater experimental system.The experimental results are compared with the optimization results to verify the correctness of the optimized simulation results.The results show that changing the opening area of primary air baffle can adjust the uniform distribution of primary air.By adjusting the opening position to change the direction of air intake,the gas flow at the outlet of the fire can be uniformly distributed.The position of air of 1# burner should be moved up by 1 mm,and the upper part of the hole is fully opened.The position of air hole of 2#~12# burner can be moved down by 1 mm,and the lower part of air hole of 6# burner can be moved The larger the horizontal distance d(3mm < d < 6mm)between the gas distributor and the injector entrance center,the more uniform the methane concentration distribution at the fire,the better the position d is 6mm;the larger the vertical distance h(0mm < h < 1.5mm,moving upward)between the gas distributor center and the injector entrance center,the more uniform the methane concentration distribution at the fire first increases and then decreases greatly,and the best position h is 1mm.4#~8# burners correspond to the front side of the gas distributor without gaps,1#~3# and 9#~12# burners have corresponding gaps on the front side of the gas distributor,which has obvious effect on the uniformity distribution of methane concentration at the enhanced fire,4#~8# burner concentration deviation 12% decreased to 4.2%,1#~3# and 9#~12# burner concentration deviation 5.8% decreased to 5.2%.By adjusting the air inlet position and distribution,It improves the backflow of the inlet air and the vortex in the passage to make the velocity distribution at the air outlet uniform. |
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