目前，榆林30万标方/天液化天然气装置改造项目，成功产出-160℃低温LNG产品。原LNG装置液化温度仅为-142℃，生产的LNG产品属于高温产品，在市场上无法满足客户的要求，缺乏市场竞争力，致使高温LNG产品出厂价格比周边市场低温LNG产品出厂价格低100~150元/吨，导致原LNG装置的经济性差，效益低。
原装置采用国外液化工艺及其液化设备，具有系统紧凑复杂的特点。针对原LNG装置的工艺流程及现场条件，提出基于原装置的多循环再液化工艺整改方案，具有技术简单、设备数量少、投资低、效率高、稳定性强等优点。在业主的积极配合下，该装置从改造工艺方案设计、设备及仪表阀门采购、设备制造、管道采购与预制、管道设备安装、试压检验、吹扫置换、开车调试，生产出合格的-160℃的低温液体LNG产品，仅仅花费3个月时间。为了缩短停车时间，最大程度降低停车给业主带来的经济损失，提出根据现场实际情况，采用全场三维建模进行工程设计，采用场外管道预制、现场焊接的施工方案，最终将LNG装置停车、吹扫置换、安装、焊接、试压检验、吹扫置换、开车调试等工作控制在10天内完成。
改造后的LNG装置，生产的LNG属于低温产品，不仅满足更多客户需求，而且能够为企业增加净利润600~700万元/年，创造显著的经济效益。
At present, the renovation project of 300,000 standard square meters/day liquefied natural gas plant in Yulin has successfully produced -160℃ low-temperature LNG products. The liquefaction temperature of the original LNG plant is only -142℃, and the LNG products produced are high-temperature products, which cannot meet the requirements of customers in the market and lack market competitiveness, resulting in the ex-factory price of high-temperature LNG products is 100~150 yuan/ton lower than the ex-factory price of low-temperature LNG products in the surrounding market, resulting in poor economy and low benefit of the original LNG plant.
The original plant adopts foreign liquefaction process and liquefaction equipment, which has the characteristics of compact and complex system. According to the process flow and site conditions of the original LNG plant, a multi-cycle reliquefaction process rectification scheme based on the original plant is proposed, which has the advantages of simple technology, small amount of equipment, low investment, high efficiency and strong stability. With the active cooperation of the owner, the device from the transformation process design, equipment and instrument valve procurement, equipment manufacturing, pipeline procurement and prefabrication, pipeline equipment installation, pressure test, purge replacement, commissioning, the production of qualified -160℃ cryogenic liquid LNG products, only took 3 months. In order to shorten the parking time and minimize the economic loss caused by parking to the owner, the construction scheme of off-site pipeline prefabrication and on-site welding is proposed according to the actual situation of the site. Finally, the LNG plant parking, purging replacement, installation, welding, pressure test, purging replacement, commissioning and other work is controlled within 10 days.
After the transformation of the LNG plant, the LNG produced is a low-temperature product, which not only meets the needs of more customers, but also can increase the net profit of the enterprise by 6 to 7 million yuan/year, creating significant economic benefits.