上海石化PTA装置用能优化改造方案

Optimization of Energy Efficiency of PTA Plant

上海石化精对苯二甲酸(PTA)装置能耗较高,为170kg标油/t,2007年装置综合能耗构成中,电耗占53.53%。氧化单元副产低压蒸汽未能有效利用,对苯二甲酸(TA)分离工艺落后,精制母液循环量增加,水耗高,污水排放量大是造成装置能耗高的原因。提出PTA装置用能优化改造方案:改造空压机组,用氧化单元副产低压蒸汽透平加废气膨胀透平驱动的空压机组取代电机驱动;采用压力过滤机系统替代压力离心机系统;采用两级膜过滤技术循环回用精制母液。分析显示,优化方案实施后,预计装置空压机系统将节电8970×104(kW·h)/a,精制分离系统将节电360×104(kW·h)/a,综合能耗将由170kg标油/t降至131kg标油/t。

The energy consumption of SINOPEC Shanghai Petrochemical Co.,Ltd＇s PTA plant was relatively high,at 170kg of oil equivalent per ton.In 2007,power accounted for 53.53% of all energy used by the plant.Low-pressure steam produced as co-product from the oxidation unit of the plant was not utilized effectively ;the TA separation technology used in the plant was outdated;the volumes of circulating refined liquor needed increased;water consumption was high;the volume of sewage discharged was large.These were the causes of the high energy consumption of the PTA plant.Technicians of the company proposed a plan to raise the energy efficiency of the plant： ①revamp the air compressor unit by using an air compressor unit driven by low-pressure steam （from the oxidation unit） turbines and exhaust gas expansion turbines to replace the air compressors driven by motors; ②substitute a pressure filter system for the pressure centrifuge system; ③recycle the refined liquor using the double-pass membrane filtering technology.Analysis shows that after the optimization,power used by the air compressor system is expected to drop by 8970×10^4 （kW·h）/a,power used by the refining and separation system will drop by 360×10^4 （kW·h）/a,and the overall energy consumption of the plant is expected to drop to 131kg of oil equivalent per ton from 170kg of oil equivalent per ton.