Development of methanol synthesis technologies at home and abroad

　　The technology for methanol production is highly mature, and the main advancement in this field in recent years has been the improvement of methanol synthesis towers. However, several new processes have been developed recently, such as the KVAERNER/BP process jointly developed by KVAERNER and BP, ICI’s LCM process and the improved LCM process; in addition, some new technologies are also under development. The author of this article focuses on the recent advancements in methanol synthesis processes, highlighting the KVAERNER/BP process, the LCM process, and improved versions of the LCM process. 1 KVAERNER/BP process Developing new gas generation processes has been a major focus in the advancement of new methanol synthesis methods in recent years. The KVAERNER/BP process, developed jointly by KVAERNER Company and BP Company, is based on the new type of converter developed by BP. The converter is of coaxial tubular type, with a simple structure. The outside of the tube wall is filled with a conventional steam reforming catalyst; natural gas mixed with water vapor flows along the outside of the tube wall. The effluent from the outer top of the tube wall is collected and then fed into an oxygen-containing reaction chamber for partial oxidation, after which it enters the inner tube filled with a two-stage conversion catalyst. The energy released by partial oxidation and the two-stage conversion of the inner tube can meet the requirements for steam conversion in the outer tube. The KVAERNER/BP process using BP conversion reactors has the following features: (1) The conversion reactors are lightweight, easy to manufacture, and cost-effective; (2) The operation of the conversion reactors takes place at pressures similar to those in the methanol synthesis loop, which does not require compressors – only one compressor for the raw material (natural gas) is needed; (3) There is no need for a high-pressure steam system; (4) The system uses air instead of pure oxygen, so air separation equipment is not required. The disadvantage is that N2 is introduced and must be separated from the syngas. Membrane separation device for purifying syngas. Methanol synthesis reactors can be traditional quench-type reactors, or they can also be axial-radial mixed-flow reactors or other similar improved designs. The process make-up air compressor can be eliminated, but the circulation compressor remains necessary. According to KVAERNER, the crude methanol produced using this process has a higher quality than that produced by traditional methods; as a result, only one distillation tower is needed to achieve an “AA” grade or meet IMPCA standards. 2 LCM process and improved LCM process: ICI’s LCM methanol process was developed based on its advanced gas-heated converter technology. After the successful development of the ICI gas-heated converter, it was first applied in ammonia plants; this is the LCA ammonia synthesis process developed by ICI. ICI built a plant using this process in Severnside, UK. Subsequently, ICI considered applying this technology to methanol production and developed an advanced LCM process. With the assistance of BHP in Australia, the new process was tested on a pilot plant with a capacity of 54,000 t/year, yielding key data. The LCM process developed on this basis is similar to traditional processes, but due to the improvement of the conventional two-stage converter, its overall design is simpler. The basic process is as follows: Natural gas is compressed and desulfurized, then, after becoming water-saturated, it enters the steam conversion section of the converter. The heat required for the first stage of steam conversion is provided by the second stage of partial oxidation. A stream of gas from the first converter enters the second converter, where it is partially oxidized using air; the resulting hot gas stream then enters the catalyst bed in the second converter for further conversion. Since air is used instead of pure oxygen for partial oxidation, the syngas contains a large amount of nitrogen, which must be removed before it enters the methanol synthesis tower. Nitrogen removal is carried out using a membrane separation unit. A large-scale methanol plant only requires one membrane unit. The LCM process was initially designed to use an ICI gas-heated converter. Since 1998, this process design has adopted a more advanced ICI improved gas-heated converter, and the process that uses this new type of converter is known as the improved LCM process. The process is as follows: Natural gas is compressed to 4 MPa, desulfurized, and then fed into a water saturator for saturation. It is subsequently preheated to about 400°C. The natural gas that enters the ICI improved gas heating converter passes through tubes filled with conventional conversion catalysts; the partially converted gas exiting these tubes is collected at the bottom of the reactor before entering the second-stage converter. The gas is partially oxidized in the two-stage converter. The hot exhaust gas from the second-stage converter is returned to the improved gas-heated converter, where it passes through the shell side of the reactor. The stream from the second reactor, after heat exchange, is further cooled through heat exchange before entering the methanol synthesis loop. The synthesis circuit is similar to traditional processes, still primarily using a cooled tubular reactor. A key feature of this process is its conversion pressure, which reaches up to 4 MPa – significantly higher than the 1.5–2 MPa conversion pressure used in traditional steam conversion. As a result, the load on the syngas compressor is reduced, which in turn lowers both the investment required for the compressor and the electricity consumption. Product fractionation is carried out using a double-column distillation system; the liquid by-products are recycled back to the water saturator, while the purge gas is used as fuel for auxiliary boilers or to generate power via gas turbines. Share materials! ! ! !

What about domestically? Which organizations possess unique technologies in this area?

Currently, the methanol projects under way in China are all large-scale, with capacities of over 600,000 tons each. These projects mostly rely on foreign technology, as domestic technology is not yet mature enough.

Abroad, methanol synthesis technologies are primarily designed to produce methanol from natural gas, whereas in China, the production of methanol from natural gas has been explicitly prohibited by the National Development and Reform Commission. Domestic methanol plants mainly use coal as the feedstock. The methanol synthesis feed gas obtained through conversion using natural gas as a raw material differs significantly in composition from the gas generated by coal gasification. Gasification is used to produce methanol feed gas, which contains a high level of CO; the engineering experience gained abroad in natural gas facilities may not be entirely applicable to China. It is recommended that domestic enterprises should not be overly reliant on foreign technologies when choosing methanol production methods – especially for large-scale methanol plants!

Methanol production from CO, Kunming University of Science and Technology

Currently, there are two companies in China that possess large-scale methanol production technology (200,000 tons per year per system). 1. Hangzhou Linda Company, which has a significant track record in methanol production, capable of handling operations on various scales； 2. East China University of Science and Technology: a single-system shell-and-tube reactor with a capacity of 200,000 tons per year. You can consult on 5.0MPa 1# by yourself

Agreed! In a sense, foreign technology suppliers are conducting tests in China at the moment. As for methanol production facilities using coal as feedstock, how many such facilities have actually been built abroad? Whether it’s LURGI, DAVY, TOPSOL, or CASALE, which one has significant achievements in coal-based methanol production?