碱洗塔废碱系统黄油回收探索

EXPLORATION IN GREASE RECOVERY FROM SPENT CAUSTIC SYSTEM OF CAUSTIC SCRUBBING TOWER

裂解气中的酸性气体含量（摩尔分数）为0．2％～0．4％，一般要求将裂解气中的H2 S和CO2分别脱除至体积分数1 mL／m3以下。通常乙烯装置采用碱洗法脱除裂解气中的酸性气体。上海石化乙烯装置老区裂解气压缩机三段出口设有碱洗系统，用NaOH溶液洗涤裂解气，以除去裂解气中的H2 S及CO2等酸性气体，防止下游催化剂中毒和污染乙烯产品。碱洗系统不断排出废碱液，而含有大量黄油的废碱液常因含油量不合格，给下游处理设施的操作带来困难。黄油通过装车外送处理，也给环保带来了压力。结合碱洗塔黄油生成的原因，通过对黄油回收系统进行改造，将黄油回收至急冷系统。

The acid gas content of cracking gas is about 0.2% ~ 0.4%( mol),and generally the H2S and CO2 contents of cracking gas are required to be below 1 ppm. Ethylene plant usually uses caustic scrubbing method to remove the acid gas in cracking gas. A caustic scrubbing system is installed at the 3rd stage outlet of cracking gas compressor in the ethylene plant at SINOPEC Shanghai Petrochemical Co.,Ltd.,and NaO H solution is used to scrub the cracking gas,so as to remove acid gas such as H2S and CO2 in the cracking gas and to prevent the downstream catalysts from being poisoned and the ethylene products from being polluted. The caustic scrubbing system continuously discharges spent caustic which contains a large amount of grease,resulting in difficulties in the operation of downstream treatment facilities. The grease has to be delivered for disposal, arousing concerns over environmental protection. Combined with the reasons for grease formation in caustic scrubbing tower,the grease recovery system is modified to recover the grease to quench system.