榆林气田含油含醇污水预处理工艺改造效果评价

污水预处理直接关系到后续处理能否正常运行。榆林天然气处理厂污水预处理系统自投产以来经常出现过滤器、换热器堵塞，无法加入药剂等现象，致使污水处理效果不理想。为此，通过深入分析该厂含油含醇污水预处理工艺存在的问题，进行了工艺改造，优化了工艺流程和加药方案，变原来的两级沉降两级除油为三级沉降三级除油，并在加药流程前增加蒸气混合加热器，使预处理药剂絮凝反应效果达到最佳。改造取得了满意的效果，预处理后的含醇污水油含量降至20 mg/L，铁离子含量降至0.5～1.0 mg/L，悬浮杂质浓度小于5 mg/L，含油含醇污水透光率在95%以上,既可以满足甲醇回收装置的进料要求，又有效缓解了后续设备、管线堵塞的问题，达到了预期目标。

RESULT EVALUATION ON THE INNOVATED PRE TREATMENT TECHNOLOGY OF SEWAGE CONTAINING OIL AND METHYL ALCOHOL IN YULIN GAS FIELD

The preliminary treatment, related to the sequent procedures, plays an important role in the whole process of sewage disposal. The pre treatment system in the Yulin Natural Gas Processing Plant has never worked smoothly since put into production because many various problems occurred so often that the waste water could not be treated well, for example, the treatment chemicals could not be injected due to the choked filters or heat exchangers. Through deep investigation into the existing problems in this plant, this study reformed the previous technology and optimized its flow process, i. e., the settling out and deoiling being upgraded to three steps from the former two steps, the flocculating effect being improved by steam mixed heating apparatus added before injecting the treatment chemicals. The reformed technology has been proved to achieve in good results as follows: after preliminary treatment the oil content of the sewage decreased to 20 mg/L, the ferric ions content declined to 0.5-1.0 mg/L, and the content of suspended admixture to less than 5 mg/L. The light transmittance of the sewage after pre treatment was up to over 95%, which could not only satisfy the request for entering material of the methyl alcohol distillation tower but also alleviate the choking problems happened to the equipments in following process and pipelines. Therefore this reformed technology has been proved successful in practical use in this plant.