What are the methods for producing methanol?

In China, there are three methods for producing methanol: from coal, from natural gas, and from coke oven gas.

There are different classifications based on various criteria. By raw material: natural gas, coal (coking gas, gas), petroleum, and others (including CO2 from Iceland, biomass, etc.). By pressure: high pressure, medium pressure, low pressure. By production scale: large-scale, medium-scale, small-scale. By process package: domestic ones (such as LinDa, Huachang, Anchun, Jutuo, etc.) and foreign ones (such as Davy, Lurgi, Topsoe, Cassali, Toyo, etc.). . . . . .

Foreign methanol production technologies: Abroad, 92% of methanol is produced using natural gas as a raw material, while 2.3% is produced from coal; therefore, the methanol production technologies used by foreign companies are all focused on producing methanol from natural gas. The advanced methanol production process technologies widely adopted internationally include DAVY (formerly I.C.I), OPSOE, UHDE, and Lurgi’s methanol technologies. The consumption and energy requirements of these different methanol technologies vary little; the main difference lies in the type of methanol synthesis reactor used. 1. 1 Technical features of DAV Y methanol technology: The advantage of the DAV Y low-pressure methanol synthesis technology lies in its high-performance catalysts for low-pressure methanol synthesis. The synthesis pressure ranges from 5.0 to 10 M Pa; in large-scale methanol production facilities, this pressure is 8 to 10 M Pa. The types of synthesis towers are as follows: The first type is the quenching-type synthesis tower, which has a high production capacity per tower, with a methanol concentration at the outlet of approximately 4–6% vol. The second type is the internal heat-exchange cold-tube methanol synthesis tower. A tubular synthesis tower was also developed. Distillation mostly uses two columns; sometimes three-column distillation is employed as well, with consideration given to the setup of the steam system. Steam system: It is divided into three categories – high pressure at 10.5 M Pa, medium pressure at 2.8 M Pa, and low pressure at 0.45 M Pa. The waste heat generated by the conversion process, along with the waste heat from the flue gases of the converter, is used to produce high-pressure superheated steam at 10.5 M Pa and 510°C. High-pressure superheated steam is used to drive the synthesis compressor steam turbine, while medium-pressure steam is extracted for use within the plant. 1. 2 L Urgi methanol technology: Lurgi’s synthesis process has its own characteristics, namely its own patents for synthetic towers. It is characterized by a tubular reactor; secondary steam is generated, with the Lurgi synthesis catalyst inside the tubes and boiler water outside them, producing saturated medium-pressure steam at 3.5–4.0 M Pa. Due to the extremely large diameter of large-scale units such as synthesis towers with a capacity of 2000 M TPD, two synthesis towers are often used in parallel. For larger scales, a shell-and-tube synthesis tower is used, followed by another cold-tube or hot-tube synthesis tower; alternatively, two series of synthesis towers can be connected in parallel. The distillation in the Lurgi process employs three-column distillation, or three-column distillation followed by a recovery column. Two-column distillation is also used sometimes. The heat sources for the reboilers of the pre-distillation column and the pressurized distillation column in the three-column distillation process come from the waste heat of the conversion gas. Therefore, very little low-pressure steam is consumed in distillation. 1. Technical features of methanol production at TO PSO E: TO PSO E is a major provider of patent technologies and catalyst manufacturer in the fields of ammonia synthesis and methanol production. The technical features related to methanol production include the use of BWR synthesis towers (with tube banks for steam generation) or CMD multi-bed adiabatic synthesis towers for methanol synthesis. Its process characteristics are as follows: an axial adiabatic bed is used, heat exchangers are installed between the towers, and waste heat is utilized to preheat the boiler feedwater or the hot water circulating in the saturated system. The temperature entering the tower is 220°C. It features a high one-way conversion rate, a small catalyst volume, a simple structure for the synthesis tower, and large production capacity per series. The synthesis pressure is 5.0–10.0 M Pa, optimized according to the equipment capacity. The Nissan 2,000-ton methanol plant has a synthesis pressure of approximately 8 M Pa. A three-tower or four-tower (including a recovery tower) process technology is employed. 1. Technical features of the 4 TEC methanol process: The synthesis process utilizes IC I low-pressure methanol technology. Distillation uses Lurgi’s technology. The synthesis was carried out using an IC I low-pressure methanol synthesis catalyst. Synthesis tower: An MRF-Z synthesis tower using TEC (multi-layer radial synthesis tower), with a methanol concentration at the outlet of up to 8% vol. The pressure drop in the synthesis tower is low, at 0.1 M Pa. The waste heat from methanol synthesis is used to generate medium-pressure steam at 3.5–4.0 M Pa; this medium-pressure steam can be used as process steam or, after being superheated, as steam for driving turbines. 1. 5 Technical features of Mitsubishi Heavy Industries’ methanol technology: Mitsubishi’s methanol technology is similar to the I.C.I. process, and its characteristic is the use of a super methanol synthesis tower with a unique structure. The synthesis pressure is related to the capacity of the methanol plant. The Nissan 2,000-ton methanol plant has a synthesis pressure of approximately 8.0 M Pa. The super methanol synthesis tower is characterized by the use of a double-tube design, which ensures uniform catalyst temperature and a high one-pass conversion rate; the concentration at the outlet of the synthesis tower can reach up to 14% vol. The synthesis tower generates 3.5–4.0 M Pa of medium-pressure steam as a by-product; the outlet concentration can reach 8–10% vol. The circulation volume of the synthesis system is significantly reduced compared to traditional technologies, resulting in minimal consumption of make-up gas. 2-tower or 3-tower distillation is used, depending on the steam system setup. 1. The methanol production technology of Wood Company 6 features an I.C.I. low-pressure synthesis process along with corresponding catalysts; the synthesis pressure in a plant with a daily output of 2000 tons of methanol is 8.0 M Pa. Synthesis tower: Wood Company uses improved air-cooled shock-type diamond reactors, isothermal synthesis towers, and cold-tube synthesis towers. The ARC synthesis tower of CA SAL E company (multi-layer axial radial synthesis tower) can achieve a maximum production capacity of 3,000 MTPD per unit. Synthetic waste heat recovery method: Preheating boiler feed water, with low equipment investment. Isothermal synthesis tower: A shell-and-tube synthesis tower that generates medium-pressure steam, with a steam pressure of 3.5–4.0 M Pa; the maximum production capacity per tower can reach 1200 M TPD. Equipment investment is high. Cold-tube synthesis tower: axial configuration with indirect heat exchange via cold tubes; the maximum production capacity of a single tower can reach 2000 M TPD. Low equipment investment. 2-tower, 3-tower, or 4-tower distillation can be employed, with the following comparisons: for 2-tower distillation, the methanol recovery rate is 98.5%, and 1.2 tons of low-pressure steam are required per ton of methanol produced. 3-column distillation: the methanol recovery rate is 99%, and 0.47 tons of low-pressure steam are required per ton of methanol produced. 4-column distillation, with a methanol recovery tower; the methanol recovery rate is 99.5%, and 0.45 tons of low-pressure steam are required per ton of methanol produced. 1. Features of Linde’s methanol technology include the use of an I.C.I. low-pressure synthesis process and catalysts. A spiral-tube isothermal synthesis tower utilizing by-product steam is used; the tubes are filled with boiler water, the medium-pressure steam pressure ranges from 3.5 to 4.0 M Pa, which reduces gas resistance. The rest is similar to IC I low-pressure methanol.