RU2252209C1 - Method for methanol production (variants) - Google Patents

Abstract

FIELD: technology for production of methanol from syngas.

SUBSTANCE: claimed method includes mixing of hydrocarbon raw material with water steam to provide syngas by steam conversion of hydrocarbon raw material and subsequent methanol synthesis therefrom. Conversion of hydrocarbon raw material and methanol synthesis are carried out under the same pressure from 4.0 to 12.0 MPa. In one embodiment hydrocarbon raw material is mixed with water steam and carbon dioxide to provide syngas by steam/carbonic acid conversion of hydrocarbon raw material in radial-helical reactor followed by methanol synthesis therefrom under the same pressure (from 4.0 to 12.0 MPa). In each embodiment methanol synthesis is carried out in isothermal catalytic radial-helical reactor using fine-grained catalyst with grain size of 1-5 mm. Methanol synthesis is preferably carried out in two steps with or without syngas circulation followed by feeding gas from the first or second step into gasmain or power plant.

EFFECT: simplified method due to process optimization.

12 cl, 3 tbl, 3 dwg

Description

The invention relates to methods for producing methanol from hydrocarbons and can be used in gas, chemical, petrochemical, oil refining and other industries.

Methanol is widely used in many industries as a solvent, as a starting material for the production of polymeric materials, organic dyes, medicinal substances, etc.

Methanol can be obtained from hydrocarbon feedstocks, for example from natural gas, associated gases from oil production, and naphtha. The main raw material for methanol production is natural gas.

The main industrial method for the production of methanol is the synthesis gas synthesis by steam, steam-oxygen or steam-carbon dioxide conversion of natural gas, followed by the synthesis of methanol by reduction of carbon monoxide and hydrogen dioxide on a catalyst.

Steam conversion of natural gas with dosing of carbon dioxide (steam-carbon dioxide conversion) provides a more optimal ratio of reacting components in the initial gas mixture for methanol synthesis.

The main stages of methanol production are:

- compression of natural gas to the pressure of synthesis gas production;

- purification of natural gas from sulfur compounds;

- production of synthesis gas;

- compression of synthesis gas and circulating gas to the pressure of methanol synthesis;

- methanol synthesis;

- rectification.

Syngas for methanol production is obtained in tube furnaces by steam conversion of hydrocarbons at a pressure of 1.5-2.0 MPa and in shaft reactors by steam-oxygen conversion of hydrocarbons at a pressure of up to 7.5 MPa. Sometimes these processes are combined, carrying out the conversion process in two stages at a pressure of up to 4.0 MPa.

Methanol synthesis is carried out on a high-temperature zinc-chromium catalyst at a temperature of 310-400 ° C and a pressure of 27.5-43.1 MPa or on a low-temperature zinc-copper-aluminum or zinc-chromium-copper catalyst at a temperature of 200-280 ° C and pressure 5-10 MPa in axial or radial type reactors.

Along with the synthesis of methanol, reactions of the formation of by-products, such as water, carbon dioxide, methane, ethers, higher alcohols, acids, etc., occur simultaneously.

In order to increase the selectivity of the process, preferential production of methanol, it is important to carry out the process at the optimum temperature.

The traditionally used methanol synthesis catalytic reactors are distinguished mainly by axial or radial movement of the medium flow through the catalyst bed and by the method of heat removal from the reaction zone.

To remove heat from the reaction zone, cold gas (bypass) is supplied to the main gas stream in front of each catalyst shelf. Another way to remove heat from the reaction zone is to place tubular or coil heat-exchange elements between the catalyst shelves or in the catalyst layer of the reactor. (Karavaev M.M., Leonov V.E., Popov I.G., Shepelev E.T. Technology of synthetic methanol. - M.: Chemistry, 1984, - 240 p., Ill.).

The main disadvantages of the traditional method of producing synthesis gas are:

- pressure limitation of the natural gas conversion process in tube furnaces;

- the need to use oxygen in the process of converting natural gas in mine reactors;

- significant energy costs for compression of natural gas, synthesis gas and circulating gas;

- the high cost of natural gas conversion equipment and compressors.

The disadvantages of the methanol synthesis process are:

- the use of a less active catalyst with relatively large granule sizes;

- a relatively large loss of gas pressure during the passage of the granular catalyst bed;

- the inability to ensure the synthesis process at the optimum temperature;

- large size, complex design and high cost of catalytic reactors.

The present invention is based on the task of creating a method for producing methanol, simplifying the technological scheme by carrying out processes of steam or carbon dioxide conversion of natural gas and methanol synthesis at the same pressure of 4.0-12.0 MPa.

The problem is solved in that the synthesis gas is obtained by steam or carbon dioxide catalytic conversion of hydrocarbon feeds, for example, natural gas, is carried out in a radial-spiral type catalytic reactor at the same pressure from which methanol synthesis is carried out, from 4.0 to 12 , 0 MPa. The conversion process is carried out in a radial-spiral type reactor with external heat input.

In this case, you can use the pressure of natural gas coming from a well or main gas pipeline. This allows excluding compressors of natural gas and synthesis gas from the circuit. In this case, methanol synthesis will be carried out at the same or slightly reduced pressure (due to pressure loss in the path from the hydrocarbon conversion reactor to the methanol synthesis reactor), in which the hydrocarbon conversion is carried out, i.e. from 4.0 to 12.0 MPa .

The exclusion of compressor equipment from the methanol production scheme will reduce capital and operating costs and increase the reliability of the installation.

The use of steam-carbon dioxide conversion will allow to obtain a more optimal composition of the synthesis gas to obtain methanol.

Methanol synthesis is carried out in a radial-spiral type isothermal catalytic reactor.

The use of an isothermal radial-spiral type catalytic reactor in comparison with traditionally used reactors allows using the most active fine-grained catalyst, ensuring the synthesis process under optimal temperature conditions, a high degree of conversion, high selectivity of the process, minimal catalyst volume, minimal loss of pressure of the reaction gas when passing through granular catalyst bed. The possibility of overheating of the catalyst is completely eliminated.

The optimal temperature conditions for carrying out the methanol synthesis process and the high selectivity of the process are ensured by a developed heat exchange surface located in the catalyst layer. Maintaining a predetermined temperature in the catalyst bed located between the spiral-shaped walls is ensured by the pressure of boiling water (or other coolant) in the cavities of the spiral-shaped walls. This eliminates overheating of the catalyst, both during its recovery and during its operation.

The minimum catalyst volume and a high degree of conversion are provided by using a highly active fine-grained catalyst with a granule size of 1-5 mm.

The radial-spiral course of the reaction gas through the granular catalyst bed provides minimal head loss.

The reaction heat released during methanol synthesis is completely utilized for steam production.

The use of a radially spiral type methanol synthesis reactor ensures a stable temperature in the reaction zone under all operating conditions — during catalyst recovery, during start-up, at partial or full load.

Methanol synthesis can be carried out in one or two steps using a circulation compressor.

It is also possible to carry out the methanol synthesis process in one or two stages, followed by gas transfer after the first or second stage to the gas pipeline and / or for use in power plants. This will exclude the circulation compressor from the circuit.

The invention is further illustrated by specific examples of its implementation and the accompanying drawings, in which:

figure 1 depicts a flow diagram of the production of methanol from natural gas with desulfurization, steam catalytic conversion of natural gas and two-stage synthesis of methanol;

figure 2 is a schematic flow diagram of the production of methanol from natural gas without desulfurization of the source gas, steam catalytic conversion of natural gas, using air cooling apparatuses and with single-stage methanol synthesis;

figure 3 is a schematic flow diagram of the production of methanol from natural gas with desulfurization, carbon dioxide catalytic conversion of natural gas and two-stage synthesis of methanol.

The proposed method for producing methanol is as follows. Figure 1 presents a schematic flow diagram of methanol production with desulphurization of natural gas, steam catalytic conversion of natural gas and two-stage synthesis of methanol.

Natural gas (GHG) enters the mass transfer apparatus 1, where mechanical impurities and gas condensate (GC) are cleaned, a natural gas heater 2 passes, where it is heated by gas after steam conversion of natural gas, and sulfur desulfurization-hydrogenation apparatus of organosulfur compounds 3 and absorption of hydrogen sulfide pass in the apparatus 4, then it is mixed with water vapor and fed to the steam conversion of natural gas to reactor 5. In the reactor 5, the process of steam catalytic conversion of natural gas takes place in two stages, m heat input to the first stage is carried out by the heat of the synthesis gas exiting the second stage, and the heat input to the second stage is carried out by heat supplied flue gas. The syngas after steam reforming of natural gas gives off heat to fresh natural gas in a natural gas heater 2, is cooled in a heat exchanger 6, and enters a separator 7, where gas condensate is separated. Next, the synthesis gas is sent to the first stage of the methanol synthesis cycle, is heated in the return heat exchanger 8 and sent to the methanol synthesis reactor 9. After the methanol synthesis reactor 9, the gas passes through the return heat exchanger 8 and is cooled in the heat exchanger 10, where the crude methanol is condensed. The raw methanol is separated in the separator 11, and the synthesis gas is sent to the second stage of the methanol synthesis cycle, where a process similar to the process in the first stage of the methanol synthesis cycle takes place, while the synthesis gas passes through the reverse heat exchanger 12, the methanol synthesis reactor 13, the reverse heat exchanger 12, heat exchanger 14 and enters the separator 15. The raw methanol from the separators 11 and 15 is collected in the raw methanol collector 16 and sent to the consumer by the pump 17. Part of the gas after the methanol separator 15 is sent as fuel to the burner of the reactor 5, and the rest is sent to the discharge into the gas pipeline.

The heat of the flue gas (DG) after the reactor 5 is used to produce steam in the boiler 18.

The isothermal mode in the methanol synthesis reactors 9 and 13 is supported by the evaporation of water in the cavities of the spiral walls located in the catalyst bed, and the set temperature in the synthesis reactor is maintained by the corresponding pressure in the separators 19 and 20. The supply of chemically purified water (HOW) to the separators 19, 20 and 21 carried out by pumps 22 and 23.

When using natural gas not containing sulfur compounds as a raw material, desulfurization can be excluded from the technological scheme. Water cooling can also be replaced by air cooling.

Figure 2 presents a variant of the process flow diagram for the production of methanol without desulfurization of the source gas, with steam catalytic conversion of natural gas, with one-step synthesis of methanol and using air cooling devices. Gas sequentially passes the apparatus for purifying natural gas (GH) from gas condensate and particulate matter 24, a natural gas heater 25, a steam catalytic conversion reactor of natural gas 26, a natural gas heater 25, an air cooling apparatus 27, a separator 28, where gas condensate is separated (GC ) Then the gas is heated in the return heat exchanger 29 and enters the methanol synthesis reactor 30. After the methanol synthesis reactor 30, the gas passes through the return heat exchanger 29, the air cooling apparatus 31 and enters the separator 32, where the raw methanol is separated, which is sent to the raw methanol collector 33 and pump 34 is sent to the consumer.

Part of the gas after the separator 32 is sent as fuel to the burner of the reactor 26, and the rest is sent to the discharge into the gas pipeline.

The heat of the flue gas (DG) after the reactor 26 is used to produce steam in the boiler 35.

The isothermal mode in the methanol synthesis reactor 30 is supported by the evaporation of water in the cavities of the spiral walls located in the catalyst bed, and maintaining the desired temperature is supported by the corresponding pressure in the separator 36. The supply of chemically purified water (HOW) to the separators 36 and 37 is carried out by pumps 38 and 39.

Figure 3 presents a variant of the process flow diagram for the production of methanol from natural gas with desulfurization, carbon dioxide catalytic conversion of natural gas and two-stage synthesis of methanol.

Natural gas (GHG) enters the mass transfer apparatus 40, where the mechanical impurities and gas condensate (GC) are cleaned, a natural gas heater 41 passes, where it is heated by gas after steam conversion of natural gas, and sulfur desulfurization-hydrogenation apparatus of organosulfur compounds 42 and hydrogen sulfide absorption are passed in the apparatus 43, it is further mixed with water vapor and carbon dioxide and fed to the steam reforming of natural gas into the reactor 44. In the reactor 44, the steam catalytic conversion process takes place in two stages and natural gas, and the heat is supplied to the first stage due to the heat of the synthesis gas leaving the second stage, and the heat is supplied to the second stage due to the heat supplied by the flue gas. The synthesis gas after steam reforming of natural gas gives off heat to fresh natural gas in a natural gas heater 41, is cooled in a heat exchanger 45, and enters a separator 46, where the gas condensate is separated. Next, the synthesis gas is sent to the first stage of the methanol synthesis cycle, heated in the return heat exchanger 47 and sent to the methanol synthesis reactor 48. After the methanol synthesis reactor 48, the gas passes through a reverse heat exchanger 47, and is cooled in a heat exchanger 49, where the crude methanol is condensed. The raw methanol is separated in the separator 50, and the synthesis gas is sent to the second stage of the methanol synthesis cycle, where a process similar to the process in the first stage of the methanol synthesis cycle takes place, while the synthesis gas sequentially passes through a heat exchanger 51, a methanol synthesis reactor 52, a reverse the heat exchanger 51, the heat exchanger 53 and enters the separator 54. The raw methanol from the separators 50 and 54 is collected in the raw methanol collector 55 and sent to the consumer by the pump 56. Part of the gas after the methanol separator 54 is sent as fuel to the burner of the reactor 44, and the rest is discharged into the gas pipeline.

The heat of the flue gas (DG) after the reactor 44 is used to produce steam in the boiler 57.

The isothermal mode in the methanol synthesis reactors 48 and 52 is supported by the evaporation of water in the cavities of the spiral walls located in the catalyst bed, and the set temperature in the synthesis reactor is maintained by the corresponding pressure in the separators 58 and 59. The supply of chemically purified water (HOW) to the separators 58, 59 and 60 carried out by pumps 61 and 62.

An example of material flows of a method for producing methanol from natural gas, with steam catalytic conversion of natural gas, two-stage synthesis of methanol, under a pressure of 7.0 MPa is presented in table 1.

Table 1. Component composition,% vol. Raw materials In front of a natural gas conversion reactor Syngas after natural gas conversion Synthesis gas in the methanol synthesis reactor stage I Gas after stage I methanol synthesis reactor Gas to the methanol synthesis reactor stage II Gas after stage II methanol synthesis reactor Flue gas Methanol from stage I methanol separator Methanol from stage II methanol separator Raw methane Flue gas CH ₄ 90.26 21.49 5.53 8.7 11.02 12.9 15.84 19.18 0.47 0.53 0.006 - C ₂ H ₆ 6.49 1.545 - - - - - - - - - - C ₃ H ₆ 2.68 0.64 - - - - - - - - - - N ₂ 0.56 0.133 0.1 0.15 0.19 0.23 0.28 0.34 0.003 0.004 - 70.12 CO ₂ 0.01 0.002 5.17 8.13 8.97 9.85 6.3 7.19 4.11 2.26 0.65 4.05 H ₂ O - 76.19 36.44 0.07 1.4 0.004 5.79 0.014 9.18 32.29 20.31 16.77 With - - 8.53 13.41 5.02 5.906 1.66 2.016 0.12 0.031 - O ₂ - 8.22 H ₂ - - 44.23 69.54 60.14 70.87 58.45 71.08 0.66 0.50 - Ar - 0.84 CH ₃ OH 13.26 0.24 11.68 0.18 85.457 64.38 79.03 - Consumption, nm ³ / h 1450 6090 8388.9 5336 4217.4 3573 2910.7 2389.6 644.3 521.08 1116.6 21239 Consumption, kg / hour 1150.1 4880.1 4880.1 2425.9 2425.9 1535.6 1535.6 895.1 890.3 640.5 1458 25979.8 Steam / gas, m ³ / m ³ 3.2 0.57 0.0007 0.01 0.06 0.1 0.48 0.25 0.2 Pressure, MPa 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 0.03 0.03 0.03 0.002 Temperature ° C 10 314.6 420 230 230 230 230 twenty twenty twenty twenty 680

Table 2 shows an example of the main technical and economic indicators of methanol production with a capacity of 10,000 tons / year using well pressure or a gas pipeline, confirming the effectiveness of the proposed method for producing methanol.

Natural gas pressure adopted 7 MPa, methanol synthesis - two-stage.

Table 2. No. p / p Name of raw materials, products, auxiliary materials, waste Unit Indicator value 1 Natural gas nm ³ / t
nm ³ / h 1160
1450 2 Water for technological needs m ³ / t
m ³ / h 2.48
3,1 3 The annual output of raw methanol is 86% solution (in terms of 100% solution) t 11664
(10000) 4 Water for cooling m ³ / t
m ³ / h 120
150 5 Electric power kW / t kW / h 78
97.6 6 Steam to the side t / t
t / h 1,168
1.46 7 Waste gas to the side (to the gas pipeline or as fuel) m ³ / t
m ³ / h 352.4
440.5 7 Specific capital investments rub / t 7505 8 Cost of 1t. methanol rub / t 1568 nine Construction payback period years old 1,5

An increase in the capacity of the methanol production plant using the new technology will lead to further improvement of technical and economic indicators.

Table 3 presents an example of a comparison of some technical and economic indicators of methanol production with a capacity of 10.20 and 40 thousand tons per year.

Table 3. Name of indicator Units measuring Indicator value Performance t / year 10,000 20000 30000 Capital investments million rubles 75.05 90.06 105.07 Cost of 1 ton of methanol rub / t 1568 1061 773 Investment payback period from completion of construction years old 1,5 0.8 0.4

Claims (12)

1. A method of producing methanol, including purification of hydrocarbon materials from sulfur compounds, mixing it with water vapor, production of synthesis gas by steam conversion of hydrocarbon materials under pressure in a radially spiral type reactor, followed by methanol synthesis from it, characterized in that the conversion of hydrocarbon materials and methanol synthesis is carried out at the same pressure of 4.0-12.0 MPa. 2. The method according to claim 1, characterized in that the methanol synthesis is carried out in a radial-spiral type isothermal catalytic reactor using a fine-grained catalyst with a grain size of 1-5 mm 3. The method according to any one of claims 1 and 2, characterized in that the synthesis of methanol is carried out in one step without the synthesis gas circulating, followed by the transfer of gas after the first step to the gas pipeline and / or for use in power plants. 4. The method according to any one of claims 1 and 2, characterized in that the synthesis is carried out in two stages without circulation of the synthesis gas, followed by the transfer of gas after the second stage to the gas pipeline and / or for use in power plants. 5. The method according to any one of claims 1 and 2, characterized in that the synthesis is carried out in one step with the circulation of the synthesis gas. 6. The method according to any one of claims 1 and 2, characterized in that the synthesis is carried out in two stages with the circulation of the synthesis gas. 7. A method for producing methanol, including mixing hydrocarbon feedstock with water vapor and carbon dioxide, producing synthesis gas by steam carbon dioxide conversion of the hydrocarbon feedstock under pressure in a radially spiral type reactor, followed by methanol synthesis from it, characterized in that the hydrocarbon feed conversion and methanol synthesis carried out at the same pressure of 4.0-12.0 MPa. 8. The method according to claim 7, characterized in that the synthesis of methanol is carried out in an isothermal catalytic reactor of radial-spiral type using a fine-grained catalyst with a grain size of 1-5 mm 9. The method according to any one of claims 7 to 8, characterized in that the synthesis of methanol is carried out in one step without circulation of the synthesis gas, followed by the transfer of gas after the first step to the gas pipeline and / or for use in power plants. 10. The method according to any one of claims 7 to 8, characterized in that the synthesis is carried out in two stages without circulation of the synthesis gas, followed by transfer of gas after the second stage to the gas pipeline and / or for use in power plants. 11. The method according to any one of paragraphs.7 and 8, characterized in that the synthesis is carried out in one step with the circulation of the synthesis gas. 12. The method according to any one of paragraphs.7 and 8, characterized in that the synthesis is carried out in two stages with the circulation of the synthesis gas.

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