Application Of Slant Hole- Float Valve Combination Tray In Capacity Expansion Revamping Of Pangang's Coal Tar Distillation System

In this paper we break through the traditional ways that only bubble cap columns are used in tar distillation units, and an advanced and high efficiency slant-hole tray and slant hole-float valve combination tray, which have the characteristic of lower resistance, higher separation efficiency and better flexibility of operation, are adopted to replace bubble cap columns in the capacity expansion revamping. Not only does the technology solve the problems of high resistance and low production capacity in thetar distillation units, and good economy benefits are abtained, but also it's first used incivil coal coke field and worthy of being application and dissemination.Application and development of new trays in the chemical field at home and abroad have been reviewed in this paper, and the hydromechanics experiment of slant-hole tray in tar distillation units is finished, in which some parameters such as pressure drop, weeping and entrainment have been tested under the varying conditions. The experimental results demonstrate that the application of slant hole-float valve combination tray to the special mater-tar is feasible. A great deal of analogue computation by computer proves that the fraction column needs two more trays without changing its diameter when adopting slant hole-float valve combination tray as well as the second-stage evaporator needs two less trays with its diameter expanding from 1600mm to 2000mm,in the mean time the column's accessories are correspondingly revamped, the production capacity of tar distillation system in Pan Gang can expand from 8.5 104 t/a to 12 104 t/a.The hydromechanics experiment shows that the slant-hole tray and combination tray' pressure drop is obviously lower than that of bubble cap tray, the entrainment can be controlled under 10%, the wide-mouth-slant-hole tray is advantageous in reducing entrainment, and the weeping is larger when the gas loading is lower and it inverses to the gas loading. Whereas the tar expansion capacity revamping can make full use of slant-hole tray's high loading performance to avoid weeping effectively, and float valve has the advantages of automatic adjustment of gas loading, the novel slant hole-float valve combination tray can further avoid the problem. The running results shows that the coal tar throughput increases from 8.5 X 104 t/a to 14 X 104 t/a while the pressure of the second-stage evaporator's bottom drops from 0.056MPa to 0.032MPa and the energy consumption has decreased apparently. The quality of each fraction products has improved more or less, the revamping is simple and easy to carry out without any influence on the manufacture, and the investment is only 1.6 million Yuan, which is less 25 million Yuan than that of the whole column's replacing. The transformation reaches the prospective requirements of design and has remarkable economy benefits.