提高酸性水汽提装置回用水质量并降低能耗的方法探讨

Discussion on methods for improving the reused water quality and reducing the energy consumption of the sour water stripping unit

关键词:  酸性水汽提工艺  回用水  能耗  液相测线抽出  过度汽提  碱液 

Key words:  sour water stripping processes  reused water  energy consumption  liquid phase side draw-off  excessive stripping  alkali

摘要:

介绍了现有双塔加压、单塔加压侧线抽出、单塔低压全抽出等酸性水汽提工艺的主要特点,指出了现有工艺存在经汽提后的净化水作为回用水时带碱及被过度汽提等问题,提供了一种新型的带液相侧线抽出的酸性水汽提方法,即在酸性水汽提塔下部位置自上而下依次设置1#、2#无碱回用水线及碱液注入线,1#无碱回用水中NH₃、H₂S含量相对较高,可用作加氢裂化或催化裂化等装置的回用水；2#无碱回用水中NH₃、H₂S含量相对较低,可用作常减压、加氢精制等装置的回用水。该方法针对各装置对回用水不同的质量要求,采用不同的汽提深度,避免不必要的汽提蒸汽浪费,从而可实现在回用水中不含碱液的前提下大幅度降低能耗的目标。 

Abstract:

This paper introduced the sour water stripping processes including double column pressurized stripping,single column pressurized stripping with side draw-off, and single column with low pressure stripping. The problems of high alkali contents in the stripping purified water and excessive stripping in the existing processes were pointed out. A new method with liquid phase side draw-off, namely in the acid water stripper from the higher to the lower position being sequentially arranged 1#, 2# alkali free reused water line and alkali injection line, was provided. The water in the 1# line has relatively high NH₃, H₂S content; therefore it can be used as the make-up water in the hydrogenation cracking or the catalytic cracking units. The water in the 2# line has relatively low NH₃, H₂S content; therefore it can be used in the hydrotreating or the crude oil units. The method provides various degrees of stripping according to different water quality requirements from different units, so as to avoid unnecessary stripping steam consumption. Therefore, the proposed method could achieve the goal of reducing energy consumption under the premise of no alkali in the reused water.