Study On The Enhancement Of Simultaneously Heat And Mass Transfer In Hot Water Chamber

The current study is based on the key equipment of coal water slurry gasification process-evaporate hot water tower,which is used to treat the waste water.In order to solve the problem of industrial design and engineering enlargement,the experimental and theoretical methods are used to analyze the direct contact condensation of two phase in the tower,heat transfer enhancement in different contact ways and the various hydrodynamics on different tower internals.1.When the other structural parameters are same,the heat transfer efficiency of fixed valve tray increases slightly with the decrease of hole center distance,but the increasing range is not obvious;With the increase of pore diameter by 50%,the heat transfer efficiency of fixed valve tray increases by 25%;With the increase of the height of fixed valve,the heat transfer efficiency of fixed valve tray first decreases rapidly,and then it remains stable.When the other structural parameters are same,the heat transfer efficiency of sieve trays increases with the decrease of pore diameter.The influence of other structural parameters such as pore center distance and opening ratio on the heat transfer efficiency of sieve trays is not significant.Due to the different contact flow patterns,the heat transfer efficiency of fixed valve tray is better than that of sieve trays under the same structure parameters.There is an exponential relationship between number of heat transfer units and flow parameters of the two phases.This model can provide theory for the tray design and selection of industrial plants.2.The heat and mass transfer processes of the two phases in packed tower were investigated by using Raschig rings packing as two-phase contact element.During the experiment,the effects of different two-phase flow rate and packing height on the heat transfer efficiency were investigated.The relationship between the number of mass transfer units and the flow parameters is deduced as follows NTU1=ln(FLGin/FLGin-0.102)The experimental data of the direct contact condenser are verified.The average deviation is 2%,which is confirmed by the measured value of the steady-state operating condition in the experiment.It is proved that the theoretical derivation is scientific and effective.The calculation method proposed in this paper is simpler than that of the predecessors and is suitable for the quick and accurate measurement of experimental work quality.3.With the increase of the axial height,the influence of the fixed valve on the partial gas holdup in the cross-flow tray gradually decreases,and the gas holdup distribution along the radial direction gradually becomes uniform,and the effect of liquid phase flow rate on the gas holdup is more and more obvious.The partial gas holdup in the central region of the dual-flow trays is larger than that of the cross-flow trays,while the partial gas holdup in the edge regions near the tower wall is smaller than that of the cross-flow trays.The partial gas holdup on both kinds of fixed valve trays shows the trend of large in center area and small in edge area.At different axial heights of the plates,the bubble velocities along the different radial lengths of the dual-flow plates are larger than those of the cross-flow trays.The bubble velocity distributions in two different structures have similar trends,namely the bubble velocity in the central region is larger than that in the vicinity of the column wall.The gas-liquid specific surface area of dual-flow tray is larger than that of cross-flow tray in the central region,and the gas-liquid specific surface area of dual-flow tray decreases gradually with the increase of radial length.The variation of specific surface area with the radial length on cross-flow tray showed no obvious regularity,showing fluctuation.4.The pressure drop of dual-flow trays is less than that of the cross-flow trays.The pressure drop on dual-flow and the height of clear liquid increase with the decrease of hole center distance and open ratio,and increase with the increase of the pore diameter.The height of clear liquid was correlated with plate structure parameters and manipulated variables,and the fitted values were in good agreement with the experimental measurements.The gasfraction of tray is defined and the calculation formula is derived(?).Theresults show that the gas flow fraction of the perforated region decreases with the decrease of center distance of the hole,and with the increase of pore diameter and the open ratio.And the influence of pore diameter on the gas fraction is not significant in each plate structure variable.