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Application field

 

Production of medium - low - boiling fusel oil by methanol from coal

Technical background

Methanol is one of the important basic organic raw materials, which is used to produce many organic products such as chloromethane, methylamine and dimethyl sulfate. It is also one of the raw materials for the synthesis of dimethyl terephthalate, methyl methacrylate and methyl acrylate. At present, the production of methanol is mainly a synthesis method. The chemical reaction formula of the synthesis is: 2H2+CO→CH3OH. The raw materials are mainly from petroleum and natural gas. In recent years, with the continuous rise of oil and natural gas prices, coal chemical industry has been gradually concerned. Synthetic gas is obtained through coal gasification and purification, and crude methanol is obtained after acid gas is removed by low-temperature methanol washing.

In the typical process of crude methanol separation and refining, the four-column separation and refining process is often adopted, including prerectification column, pressurized distillation column, atmospheric distillation column and methanol recovery column. The crude methanol enters into the predistillation column, and the water extraction distillation is carried out by spraying process at the top of the predistillation column. After removing the light components (mainly non-condensable gas, dimethyl ether, etc.), the methanol at the bottom of the column and its high boiling point are pressurized, and then enters into the pressurized distillation column. The refined methanol condensed by vapor at the top of the pressurized distillation column enters the reflux tank, which is partly used as the reflux of the pressurized column and partly used as the output device of refined methanol products. The methanol, high-boiling components and water at the bottom of the pressurized tower enter the atmospheric tower, and the refined methanol products are extracted at the top of the atmospheric tower, and the side line is set for extraction at the bottom of the feed plate. The extracted substances are mainly methanol, water and high-boiling components, and the methanol is recovered in the methanol recovery tower, and the waste water at the bottom of the tower is treated in the biochemical system. The recovery tower is equipped with a side line to extract low-boiling fusel oil, so as to ensure the quality of fine methanol at the top of the recovery tower and the total alcohol content in the waste water at the bottom of the tower. The waste water at the bottom of the tower is sent to biochemical treatment. The low-boiling miscellaneous alcohol oil extracted from the side line of the recovery tower is mainly composed of methanol, isopropyl ether, n-hexane, ethanol, butanone, propanol, n-heptane, water, etc. The methanol content is related to the synthesis conditions, and the water content is 30~50wt.%. In this part of fusel oil, water molecules and each component form a variety of binary and multiple azeotropic substances. It is difficult to remove water by ordinary distillation, and it also increases great difficulties for further recovery of methanol in fusel oil.

The process flow

  

煤制甲醇生产中低沸杂醇油

 

1. Preheater; 2. Concentrated tower; 3. Coagulator; 4. Superheater; 5. Pervaporation film separator; 6. Percolating liquid condenser; 7. Vacuum unit; 8. Refined tower; Heat pumps.

Refined methanol section of methanol recovery tower low boiling fusel oil extraction by the lateral line, into the strong tower to strong, the strong tower after the initial dehydration of fusel oil steam from strong tower steamed out, part of the reflux condensation is used to carry strong tower, the remaining steam without condensation, through heat or through a heat pump into the pervaporation membrane separator separation after 0.01 ~ 1 wt. % fusel oil dehydration finished product steam, the water in the side of material liquid solution, and a small amount of organic matter in the form of steam through pervaporation membrane permeation fluid, infiltration surface, return after setting strong tower, tower products to enter the pervaporation membrane separator. The steam from the pervaporation membrane separator is not condensed and enters the refining tower in the form of vapor phase. Methanol products are extracted from the top of the refining tower, and residual liquid is discharged from the tower kettle for further separation and recovery of organic components.

Ethanol is made from syngas

Technical background

Ethanol is widely used in national defense chemical industry, medical and health care, food industry, industry and agriculture production. Ethanol production methods include biological fermentation and chemical synthesis. Among them, the production technology of ethanol from syngas by chemical synthesis is mature, and the production cost is significantly lower than that of grain route. There are three ways to produce ethanol from syngas. Second, ethanol production by syngas; The third is the hydrogenation of syngas to ethanol by acetic acid. No matter which ethanol production method is used, aqueous ethanol is obtained. Because of the common boiling point of ethanol and water, anhydrous ethanol cannot be directly obtained by traditional methods. At present, the production of industrial anhydrous ethanol mainly adopts azeotropic distillation, extractive distillation and adsorption separation, etc. These traditional methods of ethanol dehydration all have problems such as complicated process, high energy consumption and serious pollution.

The process flow

  

煤制乙醇

 

  

煤制乙醇

 

1. First heat exchanger; 2. First heat exchanger; 3. Rectification tower; 4. Reboiler; 5. Tower top condenser; 6. Superheater; 7. Steam permeable membrane equipment; 8. Heat pump.

The reaction products containing ethanol and water are obtained through multi-step reactions of syngas. Before entering the steam permeable film, the reaction products are separated in the distillation column. At the top or side line of the last distillation tower, 0.1-30% ethanol steam with water is produced. The aqueous ethanol steam is superheated or enters the membrane equipment after passing through the heat pump. After separation of membrane components, the membrane outlet (positive pressure side) is the ethanol product with water content of 0.01 ~ 1.

Technology advantage

The coupling technology of distillation and steam permeable membrane equipment is adopted to couple the traditional process with the new separation technology, which is not limited by azeotrope and does not need to add the third component.

Ethylene glycol from coal produces ethanol by - product

As an important basic raw material for petrochemical industry, ethylene glycol is mainly used in the production of polyester fiber, polyester plastic, antifreeze, lubricant, plasticizer, etc. It is also used in explosive, coating, ink and other industries, and it can derive more than 100 chemical products, with a wide range of USES. Used in the production of polyester, antifreeze, fine chemical products accounted for about 94%, 2.5%, and 3.5% of the total consumption.

Indirect glycol synthesis technology mainly includes methanol dehydrogenation dimerization method, dimethyl ether oxidation coupling method, hydroxyacetic acid method, formaldehyde condensation method, formaldehyde hydroformylation method and oxalate hydrogenation method, among which oxalate hydrogenation method is the most widely used and studied coal glycol technology.

Coal-based oxalate method produces syngas through coal gasification, and at the same time USES alcohol and N2O3 reaction to produce nitrite ester. Dioxalate of oxalate was obtained by oxygen coupling of nitrite on Pd catalyst. Glycol was prepared from dioxalate by catalytic hydrogenation. Methanol and ethanol are the most studied alcohols.

  

煤化工

 

The hydrogenation process of oxalate to produce ethylene glycol mainly consists of four units: esterification unit, carbonylation unit, hydrogenation unit and ethylene glycol refining unit. The esterification unit is used to produce NO from carbonylation unit and methanol ME from hydrogenation unit to obtain methyl nitrite through oxidation reaction. The function of carbonylation unit is to carry out the catalytic coupling reaction of CO and methyl nitrite MN to get the intermediate dimethyl oxalate DMO, and the reaction generates NO which is returned to the esterification unit by the separation system. A small amount of dimethyl carbonate DMC produced by the unit was separated from the DMO by the separation system. The role of the hydrogenation unit is to hydrogenate the DMO to obtain the crude product of ethylene glycol EG, and at the same time to generate ME, which is then returned to the esterification unit by the ME separation system. The unit by-products a small amount of methyl glycolate MG, ethanol Et, water and 1, 2-butanediol hydrogenation crude products. The refining unit is to refine crude EG products to obtain polyester grade EG and frozen grade EG products.

In addition to polyester-grade EG and refrigerated EG products, a stream of by-products composed of ethanol Et, methyl glycolate MG, water and 1, 2-butanediol is produced by this process. For an industrial device with an annual output of 200,000 tons of ethylene glycol, this unit produces about 10,000 tons of ethanol by-products. If the ethanol by-products can be recycled, the profit of this process can be effectively improved.

The process flow

  

煤化工

 

1. First heat exchanger; 2. First heat exchanger; 3. Rectification tower; 4. Coagulator; 5. Superheater; 6. Steam permeable membrane equipment.

The process by-product of ethanol in the first column separation removal of by-product of glycolic acid methyl ester, 1, 2 - butanediol high boiling point material, at the top of the column can rectification tower ethanol containing a small amount of water vapor, aqueous ethanol steam overheat or into the film after heat pump equipment, through the membrane component separation, membrane (positive pressure side) for ethanol production for export.