南充轻烃回收装置工艺改造方案研究

A STUDY OF THE TECHNOLOGICAL PROCESS REFORM PLAN FOR THE NGL RECOVERY DEVICE IN NANCHONG

四川南充轻烃回收装置采用热分离机制冷工艺，装置每天生产液化气１．５ｔ，轻油１．０ｔ，热分离机的等熵效率仅为３５％～４０％，丙烷收率不足１５％，回收装置经济效益较差。因此，为了提高回收装置的产品收率和经济效益，对其工艺装置进行技术改造十分必要。由于热分离机的等熵效率低，制冷效果差，热分离机出口含大量的液烃未回收，脱乙烷塔顶温度比原设计值偏高，造成回收装置丙烷收率低。采用ＳＨＢＷＲ状态方程作为工艺计算模型，通过工艺计算和方案对比分析，在充分利用现有流程中的设备、节省改造费用的条件下，提出了透平膨胀机制冷、二次分离的工艺改造方案。改造后的轻烃回收装置于１９９７年１２月投产，与原有装置相比，降低了制冷温度，提高了液烃收率，达到了工艺设计的改造效果。

For the NGL recovery device in Nanchong,Sichuan,the refrigerating process with heat separator is used.The device produces daily 1.5 tons of liquid gas and 1 ton of light oil,and the isoentropic efficiency of the heat separator is only 35-40% and the propane recovery ratio less than 15%,the economic benefit of the device being worse.Therefore,for enhancing the products′ recovery ratio and economic benefit of the recovery device,it is very necessary to make a technical reform to the device.A great quantity of the liquid hydrocarbon at heat separator′s outlet is not recovered due to the low isoentropic efficiency and the worse refrigerating result of heat separator,and the temperature at deethanizer′s top is on the high side than that designed,which makes propane′s recovery rate reduced.By using SHBWR state equation as the process calculation model,through the contrast and analysis of the process calculation with the plan and under the conditions of fully utilizing existing device and saving the expenses for reforming device,a process reform plan by using turbine expander to refrigerate and second separating has been put forward.The reformed NGL recovery device was put in operation in December 1997 and by comparison with original device,the refrigerating temperature was lowered and the liquid hydrocarbon recovery rate was raised,reaching the reforming result defined in process design.