提高天然气轻烃回收装置C_3^+收率的方案比选——以中坝气田为例  

Comparison and selection of schemes for C_3^+ yield increase of natural gas light ends units:A case study of the Zhongba Gasfield,Sichuan Basin

作　　者：王治红[1] 吴明鸥[2] 李涛[3] 伍申怀[3] 

机构地区：[1]西南石油大学 [2]中国石油西南油气田公司天然气研究院 [3]中国石油西南油气田公司川西北气矿

出　　处：《天然气工业》2016年第3期77-86,共10页Natural Gas Industry

摘　　要：中国石油西南油气田公司川西北矿区江油轻烃厂回收装置采用透平膨胀机单机膨胀制冷工艺,回收中坝气田天然气中C_3以上组分,因仅配备了排气量为(16~17)×10~4m^3/d的低压气增压机组,在目前天然气处理量为40×10~4m^3/d、高压原料气量最低时仅有17×10~4m^3/d、原料气压力由3.65 MPa降到2.80 MPa左右的情况下,出现了透平膨胀机的膨胀比和冷凝效率降低、低温制冷系统冷量不足、液烃产品产量和C_3^+收率下降等问题,同时,也直接影响着装置的安全、平稳运行。为了提高回收装置的C_3^+收率,提出了4种工艺改造方案:①残余气循环工艺(RSV);②直接换热工艺(DHX);③原料气增压的单级膨胀(ISS)工艺;④原料气增压+DHX工艺。对比上述4种方案的轻烃收率、能耗和经济性后认为:上述第三种方案,即原料气增压的单级膨胀工艺静态投资回收期较短(0.74年),C_3收率为89.43%、液化气产量为19.04 t/d,分别较原工艺提高了46.32%和42.94%,同时其单位能耗较低,具有更好的经济效益,适合于该装置的工艺改造。The single expansion refrigeration process of turbo expanders is used in the Jiangyou light ends unit to recover C3 components of natural gas produced from the Zhongba Gasfield, Sichuan Basin. At present, its natural gas processing capacity is 40×10^4m^3/d, the min- imum high-pressure and feed gas volume is 17×10^4m^3/d and the feed gas pressure drops from 3.65 to 2.80 MPa. Only a low-pressure gas booster set with gas discharge of （16-17）×10^4m^3/d is equipped, so expansion ratio and condensing efficiency of turbo expanders reduce, the cooling capacity of low-temperature refrigeration is insufficient and liquid hydrocarbon production and C3^＋ yield drop. Besides, the safety and smooth operation of the units are directly influenced. Thus, four process transformation schemes were put forward for C3^＋ yield increase of the light ends unit, including the Recycle Split-Vapor （RSV）, the Direct Heat Exchange （DHX） process, the Industry-Standard Single-stage （ISS） turbo-expander process, and the combined ISS-DHX process. Then, these four programs were compared in terms of the light ends recovery ratio, energy consumption and economical efficiency. As a result, with the ISS expander process was adopted, the static investment payback period became as short as 0.74 yr., the C3 yield ratio and liquefied gas production was up to 89.43% and 19.04 t/d, respectively, which is increased by 46.32% and 42.94% compared with the primary ones. And furthermore, this scheme helped decrease energy consumption and enhance economic benefit of this unit. Therefore, the ISS process is worth being recommended and mostly suit- able for the process transformation of the unit.

关 键 词：四川盆地 中坝气田 天然气 轻烃回收 残余气循环 直接换热 C_3^+收率 液化气产量 改造方案比选 

分 类 号：TE96[石油与天然气工程—石油机械设备]