Abstract: Liquefied natural gas (LNG) cold energy for air separation, with low energy consumption, low operating costs and other advantages, most of the domestic LNG receiving stations will be cold energy as the first LNG cold energy utilization projects , LNG cold energy boom rising slowly.

Liquefied natural gas (LNG) cold energy for air separation, with low energy consumption, low operating costs and other advantages, most of the domestic LNG receiving stations will be cold energy as the first LNG cold energy utilization projects, LNG cold energy The use of craze quietly rising. In this regard, industry experts suggest that LNG cold energy sub-project to be synchronized with the receiving station planning, simultaneous construction, so that the receiving station in the design can take into account the needs of cold energy separation, and further promote the LNG cold energy industry development. This is the weekend of China Chemical Industry News reporter held in Xi'an, China's first large-scale air separation technology and low temperature products application forum learned.

LNG cold energy advantage is significant

Sichuan Air Separation Equipment (Group) Co., Ltd. Jiang Rong, vice president of low-temperature technology research institute told the China Chemical Industry News reporter, LNG receiving station through the high-pressure pump and vaporized into normal temperature gas and then into the natural gas pipeline network, vaporization process LNG will release A lot of cold energy. According to the theory, the cooling capacity is estimated to be about 830kJ / kg.

Jiang Rong said: "The traditional LNG receiving station using seawater open-shelf carburetor or immersion combustion carburetor to vaporize LNG, not only a waste of valuable cold energy, but also the local waters of local low temperature pollution. Air separation temperature at -190 ℃ ~ 150 ℃, LNG vaporization temperature is -162 ℃, with the air separation of the temperature zone to match the LNG high-quality low-temperature cold energy for air separation plant, according to the use of temperature cascade can significantly reduce energy consumption, The state to promote energy - saving emission reduction and comprehensive utilization of resources projects.

According to reports, the conventional low-temperature air separation unit by the power-driven mechanical refrigeration, electricity generally accounted for about 70% of production costs, but also consume a lot of cooling water, and the use of LNG cold energy can reduce power consumption of about 56% , Process water consumption reduced by more than 99%, basically zero. And LNG cold energy separation process and simple configuration, eliminating the high and low temperature expander, simplified air separation main cold box, easy to operate, reduce energy consumption. At the same time the cooling capacity from the LNG-nitrogen heat exchanger system closed circulating liquid nitrogen, do not participate in distillation, safe and reliable.

Industrial application boom surging

As China's LNG imports continue to increase, LNG cold energy utilization development temperature. October 2010, CNOOC and the United States Air Products Company in Putian, Fujian Province, the construction of the first domestic LNG cold energy sub-project put into operation, liquid oxygen, liquid nitrogen and other production scale of 600 tons / day, four years the device running smoothly. At the same time, CNOOC in Zhejiang, Zhejiang 614.5 tons / day, Zhuhai, Zhuhai, 614.5 tons / day, and Sichuan air separation group in Hebei Tangshan 723 tons / day, Hangzhou oxygen shares in Jiangsu Rudong 600 tons / day 4 LNG cold energy Sub-projects are under construction, including Ningbo and Tangshan project will be put into operation in November, in addition to a number of LNG cold energy sub-project is being planned.

Jiang Rong told the China Chemical Industry News reporter, Sichuan Air Separation Group in the LNG cold energy separation has been three patented technology, and in a number of projects have been industrial applications. Among them, the company in Hebei Tangshan Caofeidian investment and construction projects for the current domestic largest LNG cold energy sub-project. The project uses LNG receiving stations in the oil, the daily production of 540 tons of liquid oxygen, 150 tons of liquid nitrogen, liquid argon 26 tons, 7 tons of high purity liquid oxygen.

Synchronous planning is critical

LNG cold energy air separation design, in the process conditions, interface conditions, mode of operation, etc., need to coordinate with the LNG receiving station. "However, due to different factors such as investment, LNG cold energy sub-project is often lagging behind the construction of the receiving station, it is difficult to synchronize, resulting in LNG cold energy separation design, the receiving station design has been completed, the relevant equipment has been ordered, The relevant requirements of the cold energy sub-project to modify the design of the receiving station, to the cold energy sub-sub-design, construction and operation to bring some problems. "Jiang Rong called, LNG cold energy sub-project to synchronize with the receiving station planning, So that the receiving station in the design can take into account the needs of cold energy points.

In addition, the LNG cold energy separation unit must be operated continuously for 24 hours, which requires the LNG of the receiving station to be continuously and continuously supplied. The receiving station in the early stage, affected by the downstream users, often can not guarantee the continuity of natural gas transmission. The receiving station can not supply LNG continuously for 24 hours to cold energy, resulting in cold energy separation does not work properly. This Jiangrong proposed, the receiving station in the design, in the re-condenser before the cold air in accordance with the flow of air alone set up a way LNG high-pressure pump, designed for cold energy to use, to ensure the stability of cold energy separation and continuous Sex.

There are also industry experts at the forum that although LNG cold energy and energy consumption and low operating costs, but due to increased LNG / NG related equipment, valves, etc., a one-time investment. At the same time LNG receiving station is generally built at the beach, to consider the cold energy sub-product liquid oxygen, liquid nitrogen, liquid argon market transport radius.

Nevertheless, compared to conventional air separation, LNG cold energy separation products, the combined production costs still have advantages. Jiang Rong suggested that the conditions permit, should expand the scale of cold energy production. In determining the cold energy sub-product program, the enterprise can be based on cold energy air separation in the region's market demand, and consider the cold energy of the one-time investment and product consumption, comprehensive LNG cold energy to determine the product program.