尿素装置二段蒸发喷射系统的改造及分析

分析二段蒸发喷射系统存在的主要问题，确定了提高真空度的改造方案，并应用气体动力学分析对喷射系统进行成化设计，生产运行结果表明，完全达到预期效果。

ANALYAIS AND MODIGIVSYION OF THE SECOND STAGE EVAPORATION ANDSPRAY SYSTEMS IN UREA PLANT

Since its commission,the pressure of the second stage evaporation system in the ureaplant lastcd to be higher than the design value. It is found by calculation that the sprayer of the originalthree-stage spraying system hasn't sufficient ability,meanwhile,the geometric sizes of the sprayers ineach stage and the pressure enhancer are not compatible. In addition,the heat transfer area of the mid-dle condenser is a bit small, resulting in the poor performance of the spray system. Its performance isnow not suitable for the designed production scale,but our plant plans to increase the output.Thus,thesprayers at each stage must be modified.By the analysis to the values,it is determined to redesign thenozzles of the first and second sprayers and pressure enhancer,without changing the pressure enhancingparts of the middle condenser and pressrue enhancing sprayer. Though the project increases the difficul-ty of medification,it is most economic. Using the analysis tneory of gas dynamics,we optimized tne de-sign of the spray system,and adjusted the parameters of the first and second sprayers.The most ad-vanced bell-shaped nozzle is selected for pressure enhancing sprayer,which guarantees the perfectstreamlined surface,shortens the length of the mozzle and mates the original pressure enhancer quitewell.The modified spray system was commissioned in early June,1994 , performing stably. In the pa-per,the operating parameters in 1993 and the latter ten days of July,1994 are listed and compared. Under the basically same production load and circumstances,the pressure of the second stage evaporatorafter the modification is decreased by about 50%of that before the modification. Water content in ure-a is also decreased accordingly. The process requirements can be met even in Summer.The porformanceof the spray system after modification is greatly increased, having met the expocted requirement,whichshows the modification is successfal.