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DEVICES AND METHODS OF OBTAINING A SUBSTITUTE OF GASOLINE, DIESEL FUEL (BIODIESEL)
INVENTION
Patent of the Russian Federation RU2198838

METHOD OF OBTAINING METHANOL

The name of the inventor: Pisarenko Elena Vitalevna; Pisarenko Vitaliy Nikolaevich; Abaskuliyev Jangir Ahmedovich
The name of the patent holder: Pisarenko Elena Vitalevna; Pisarenko Vitaliy Nikolaevich; Abaskuliyev Jangir Ahmedovich
Address for correspondence: 141700, Moscow Region, Dolgoprudny, ul. Tsiolkovsky, 6, sq. 57, V.N. Pisarenko
The effective date of the patent: 2002.01.29

The invention relates to a process for the preparation of methanol. The method for producing methanol includes the step of producing synthesis gas from gaseous hydrocarbons, a synthesis gas compression step, a catalytic conversion step of the synthesis gas to methanol in a reactor assembly consisting of several catalytic reactors, including the steps of heating and synthesis gas conversion in each reactor, Cooling the reaction products and separating the produced methanol after each reactor, an operation for tail gas recovery. The hydrogen obtained after vapor conversion of a part of the methanol produced is mixed with the synthesis gas to form a prepared synthesis gas with a molar ratio of hydrogen to carbon monoxide in the range of 1.4: 1 and 3: 1, and it is fed to the synthesis gas catalytic converter In methanol. The invention makes it possible to increase the productivity of the process.

DESCRIPTION OF THE INVENTION

The invention relates to the field of chemical-technological, energy-resource-saving processes for the production of methanol from natural gas or "tail" hydrocarbon-containing gases of chemical, petrochemical, gas processing and metallurgical industries.

More particularly, the invention relates to a process for synthesizing methanol from synthesis gas obtained in catalytic carbon dioxide-vapor-oxygen or steam-oxygen processes of hydrocarbon-containing gas conversion, as well as in homogeneous partial oxidation of natural gas by air or air enriched with oxygen.

In industrial production of methanol, the synthesis of methanol is usually carried out in two stages:

1. Synthesis of synthesis gas is carried out in the first stage in two types of reactors. A high-endothermic reaction of gaseous hydrocarbon vapor conversion is realized in the tube furnace and a steam-oxygen conversion of gaseous hydrocarbons unreacted in the first stage in the shaft reactor. The processes providing for the combination of these stages are also developed.

2. In the second stage, the conversion of the synthesis gas to methanol is carried out. At the same time, in order to maintain the high productivity of the catalytic reactors and to ensure sufficient purity of the methanol produced in the industrial apparatus, a gas flow flow regime close to turbulent is realized, with a low conversion of the feedstock not exceeding 5-7% , in some cases up to 15% . The unreacted synthesis gas, after separation of methanol, is fed to the synthesis gas inlet stream entering the catalytic reactor.

The disadvantages of such industrial technologies are the following:

1. High capital costs.

2. Low degree of use of the reactionary volume of industrial apparatus.

3. Use of expensive equipment.

4. Complexity of control systems.

5. Significant consumption rates for raw materials.

6. Significant energy costs.

In view of this, the cost of the methanol produced is high enough and it can not be used as raw materials for highly profitable production of monomers (ethylene, propylene) or motor fuels.

There are known industrial technologies for production of synthesis gas by high-temperature conversion of hydrocarbon-containing gases , which is incomplete combustion of hydrocarbons in oxygen or in a steam-oxygen mixture in homogeneous reactors in the absence of a catalyst. The main products of these reactions are hydrogen, carbon dioxide, carbon monoxide, water. The possibility of carrying out the process in the absence of a catalyst is ensured by a high combustion temperature of hydrocarbons. The main advantages of the high-temperature conversion process are the simplicity of the technological scheme and low capital costs.

However, this process has significant drawbacks:

1. Use of expensive pure oxygen.

2. Low molar ratio of hydrogen to carbon monoxide in the synthesis gas.

3. High consumption rates for raw materials.

4. Significant content of hard-to-remove fine-dispersed carbon in synthesis gas.

The above disadvantages of the process of high-temperature hydrocarbon conversion do not allow to significantly reduce the cost of the produced synthesis gas and, consequently, the cost of methanol.

Techniques for the production of methanol from natural gas (US 5245110) are known, which involve the production of synthesis gas as a result of the partial oxidation of natural gas by air and oxygen-enriched air. Reducing the cost of synthesis gas is achieved through:

1. Reduce the cost of producing oxygen-enriched air compared to the production of pure oxygen.

2. Use of simpler and cheaper technological equipment.

3. Reducing capital and operating costs.

In the second stage of methanol production, the synthesis gas with a high nitrogen content is converted to methanol in four or six series-connected reactors with an intermediate exit of the methanol produced in the reactors after each reactor. At the exit from the reactor block, unreacted synthesis gas enters a mass transfer membrane block, the permeate stream from which is enriched with hydrogen, mixed with synthesis gas and fed to the reactor unit, and the retentate stream is directed to the gas turbine to generate electricity. Nitrogen in the catalytic reactor system recirculates only partially together with the permeate stream, most of it is discharged into the atmosphere together with the exhaust gases of the gas turbine.

The method closest to the claimed methanol production process chosen as a prototype is the method described in the patent (RU 2152378) . In the prototype process, synthesis gas with a high nitrogen content is converted in three series-connected catalytic reactors with intermediate release of the methanol generating agent after each catalytic reactor. Due to the purposeful organization of thermal regimes of reactor operation, a given conversion of synthesis gas is ensured with high quality of the resulting target product.

The disadvantages of the known methanol production methods based on synthesis gas with a significant nitrogen content (more than 40%) are:

1. Low productivity of catalytic reactors.

2. Significant deactivation of catalysts.

3. Complexity of process control when quality of raw materials changes.

These shortcomings make it difficult to directly implement the above processes when organizing small and medium-tonnage production both in gas fields and in gas processing petrochemical and chemical enterprises.

The present invention has the following objectives: achieving high productivity of the methanol production process from natural gas, ensuring the reliability of the operation of industrial plants with a change in the composition of raw materials, increasing the catalyst operation time, obtaining high quality methanol produced, and creating energy-efficient industrial methanol synthesis plants.

These problems are solved in a methanol production process comprising the step of obtaining synthesis gas from gaseous hydrocarbons, a synthesis gas compression step, a catalytic conversion step of synthesis gas to methanol in a reactor assembly consisting of several catalytic reactors including heating and synthesis gas conversions In each reactor, the reaction of cooling the reaction products and recovering the produced methanol after each reactor, a tail gas recovery operation. The hydrogen obtained after the steam conversion of a part of the methanol produced is mixed with the synthesis gas to form a prepared synthesis gas with a mole ratio of hydrogen to carbon monoxide in the range of 1.4: 1 and 3: 1, and it is fed to the catalytic conversion synthesis reactor unit -gas into methanol.

The catalytic conversion of the synthesis to methanol is carried out in the temperature range of 160-320 ° C , pressures of 4.0-10.0 MPa , and flow velocities of 500-5000 h -1 .

Synthesis gas production is carried out at a mole ratio of oxygen: gaseous hydrocarbons of less than 0.7 .

The production of hydrogen by steam conversion of methanol is carried out in the temperature range of 120-320 ° C , pressures of 0.1-10.0 MPa , volume flow rates of 200-10000 h -1 .

The oxygen content in the synthesis gas entering the catalytic reactors for the production of methanol is up to 1.0% by volume.

The prepared synthesis gas is fed sequentially, periodically to each of the reactors in the methanol synthesis reactor unit with continuously operating the rest.

Synthesis gas is divided into two streams, one of which is enriched with hydrogen in a membrane-type mass transfer plant and fed to the methanol synthesis reactor unit, and the second hydrogen-depleted stream is mixed with the gas stream leaving the last catalytic methanol synthesis reactor and gaseous hydrocarbons and the mixture Are sent to the power and / or heat plant as a gas fuel.

METHOD OF OBTAINING METHANOL. Patent of the Russian Federation RU2198838

1 illustrates the essence of the inventive method of the invention which proposes the use of an industrial methanol production unit consisting of a synthesis gas synthesis unit 1 from a hydrocarbon feed gas, in particular natural gas, a synthesis gas compression unit 2, a synthesis gas purification reactor 3 From oxygen, synthesis gas synthesis reactor 4, methanol steam reforming, synthesis gas methanol synthesis reactors 5, 6, 7, heat exchangers 8, 13, 16 in which preheating of synthesis gas, condenser coolers 11, 14, 17 methanol production products, separators 12, 15, 18, in which condensed and non-condensable products of the methanol production reaction are separated, the product methanol container 19 is separated.

The process for producing methanol from gaseous hydrocarbons is realized in the apparatus of FIG. 1 as follows.

The starting gaseous hydrocarbons, in particular natural gas, are mixed with the oxidizing agent-air or oxygen-enriched air and sent to the reactor unit for the partial oxidation of gaseous hydrocarbons. In it, in the energy-chemical machines (internal combustion engines, gas turbines, homogeneous chemical reactors) and / or in catalytic reactors, the synthesis gas production process is carried out. Further, synthesis gas enters the compression compartment, where it is compressed to 4.0 MPa and above. Synthesis gas, obtained as a result of the partial oxidation reaction of gaseous hydrocarbons in industrial devices, usually contains 0.1-0.8 volume% oxygen. The latter has a concentration greater than its admissible steady-state concentration in the synthesis synthesis gas feeds of the methanol synthesis reactors. A decrease in the stationary oxygen concentration to 0.01-0.001% v / v is achieved in reactor 3, in which oxygen oxidation of carbon monoxide to carbon dioxide is carried out. Further, the synthesis gas with a predetermined concentration of residual oxygen is mixed with the hydrogen-containing gas coming from the methanol vapor conversion reactor 4 and fed to the heat exchanger 8 where it is heated by the product streams of the reactor 5 to a temperature close to the start temperature of the methanol synthesis reaction. After the heat exchanger 8, the synthesis gas is sent to the reactor 5, in the inlet zone 9 of which it is heated to the reaction temperature. Then, synthesis gas enters zone 10, where the main conversion of synthesis gas to methanol takes place. In zone 9, the initial reactants are heated by the heat transfer agent boiling in the jacket of the reactor 5, and in the zone 10 the reaction mixture is heated due to the occurrence of exothermic chemical reactions. From the reactor 5, the product stream passes through the heat exchanger 8, where it heats the feedstock to a temperature close to the reaction start temperature. Further, the gas stream through condenser-condenser 11 is directed to a separator 12 in which methanol is condensed. Non-condensing gases are sent to the heat exchanger 13 and further to the inlet zone of the reactor 6.

METHOD OF OBTAINING METHANOL. Patent of the Russian Federation RU2198838

The operating condition of the reactors 6, 7 is similar to that of the reactor 5. From the reactor 7, the product gas stream is fed through a condenser condenser 17 to a separator 18 where methanol is condensed and non-condensable gases are supplied to the tail gas utilization unit (shown in FIG. 2 ). The methanol produced from the collectors 12, 15, 18 is sent to the vessel 19, from which one stream is sent to the methanol purification unit and further to the consumer, and the other stream is sent to the methanol vapor conversion reactor 4. Steam to the reactor 4 is supplied from the steam drums, the heat exchange systems of the reactors 5, 6, 7. Hydrogen obtained in the methanol vapor conversion reactor 4 is mixed with the synthesis gas inlet streams of the reactors 5, 6, 7. The gas transportation system of the plant is organized in such a way that Periodically synthesis gas with increased hydrogen concentration can be fed to each of the reactors 5, 6, 7.

A variant of the methods corresponding to clause 7 is implemented as follows ( Fig. 2 ).

Raw material - natural gas is mixed with an oxidizer (air or oxygen-enriched air) and enters the reactor unit 1 of the partial oxidation of gaseous hydrocarbons. It produces synthesis gas. Further, the synthesis gas is supplied to the compressor 2, the suction line of the first stage receives a permeate stream from the membrane apparatus 20. A smaller portion of the synthesis gas stream enters the membrane apparatus 20 after the compressor 2. In 20, the total gas flow is divided into two streams. The first - permeate stream - is enriched with hydrogen, the second - the retentate stream - is depleted by hydrogen and enriched in nitrogen.

The hydrogen-rich feed stream, compressed in the compressor 2, enters the oxygen purification reactor 3 and, after mixing with the hydrogen stream from the reactor 4, is sent to the methanol synthesis reactor unit containing the reactors 5, 6, 7. The methanol produced in the 5, 6, 7, after cooling in condenser condensers 11, 14, 17 is separated in separators 12, 15, 18 from non-condensable gases, collected in a common tank 19 and discharged from the unit after distillation purification. A portion of the methanol stream is fed to the reactor 4 in which hydrogen is produced by the methanol vapor conversion reaction. The non-condensable syngas stream after the separator 18 is combined with the retentate flow of the membrane apparatus 20 and sent to the gas turbine 21 to generate electricity. The flue gases of the turbine 21 are supplied to the furnace 22 for superheating steam coming from the intertubular space of the reactors 5, 6, 7. The superheated steam enters the steam turbine 23 to generate electricity.

These examples do not exhaust all possible options for implementing the methanol production process.

Therefore, the physicochemical meaning of the present invention is that the synthesis of methanol in a nitrogen medium is carried out by synthesis gas with an adjustable ratio of hydrogen to carbon monoxide, which allows achieving high process productivity with long-term operation of catalytic systems. At the same time, the reaction rate of methanol synthesis depends to a greater extent on the hydrogen content of the feedstock than on the content of carbon monoxide in it. Therefore, the partial removal of carbon from the system as a result of the methanol vapor conversion reaction is covered with an excessively greater depth of conversion of carbon monoxide and carbon dioxide to methanol by increasing the hydrogen concentration in the synthesis gas. When steam reforming of methanol is carried out, steam formed in the heat exchange system of catalytic methanol synthesis reactors is used. The characteristics of the vapor are close to the conditions for carrying out the methanol vapor conversion reaction. Consequently, additional energy costs for carrying out this reaction are almost not required.

The invention is illustrated by the following specific embodiments of the method.

Example 1. (prototype)
1002 m 3 / h of natural gas and an oxidizer (air) are supplied to the power machine (gas turbine, internal combustion engine). 4608 m 3 / h synthesis gas is formed : hydrogen 30.05% , carbon oxide 17.41% , carbon dioxide 2.03% , and inert components 50.4% vol . For every 1000 m 3 of pure synthesis gas (without inert components), over 0.3 MW of electricity is generated. The resulting synthesis gas is compressed into 2 and purified, if necessary from oxygen in 3, fed to a catalytic reactor 5 in which methanol of 435.4 kg / h is produced at a pressure of 6.5 MPa and a temperature of 200 ° C. The reaction mixture of 5 is cooled in the heat exchanger 8, the condenser-condenser 11, and in the separator 12, the methanol is separated from the synthesis gas. The noncondensed gas stream is heated by reaction products from 6 to 13 and fed to a reactor 6 in which methanol is produced at a pressure of 6.4.8 kg / h at a pressure of 6.4 MPa and a temperature of 210.degree. The composition of the reactants at the inlet 6 is as follows: hydrogen 20.5% by volume , carbon oxide 13.15% by volume , carbon dioxide 2.47% by volume , the vapor-gas mixture of reaction products of the reactor 6 is cooled in a heat exchanger 13, Condenser 14 and methanol is separated from the reaction products in the separator 15. The non-condensable components of the gas are hydrogen: 16.98 vol.% , Carbon monoxide: 11.61 vol.% , Carbon dioxide: 2.66 vol.%, After heating in the heat exchanger 16 are fed to the catalytic reactor 7 in which, at a pressure of 6.3 MPa and a temperature of 210 ° C., 35.84 kg / h of methanol are formed. The total amount of methanol produced is 599.04 kg / h . The composition of the obtained product methanol: water - 2.5% by weight , methanol - 97.5% by weight , organic impurities in trace amounts. "Tail gases" are sent to a gas turbine for power generation.

Example 2
1002 m 3 / h of natural gas and an oxidizer (air) are supplied to the power machine (gas turbine, internal combustion engine) and catalytic reactor. 4608 m 3 / h of synthesis gas is formed : hydrogen 30.05% , carbon oxide 17.41% , carbon dioxide 2.03% , inert components 50.4% Every 1000 m 3 of pure synthesis gas (without inert components) produces over 0.3 MW of electricity. Synthesis gas in the presence of a small amount of oxygen in it is sent to the reactor 3 to carry out the process of selective oxidation of carbon monoxide to carbon dioxide. A part of the methanol produced in the reactors 5, 6, 7 in the amount of 104.96 kg / h is subjected to the methanol vapor conversion reaction in the reactor 4 and the hydrogen produced is fed to the feed of the synthesis gas. Prepared synthesis gas of the composition : hydrogen 32.65% vol . ; carbon oxide 16.3% vol. , Carbon dioxide 1.9% vol. % Is sent to a catalytic reactor 5 in which methanol is produced at a pressure of 6.5 MPa and a temperature of 200 ° C. in an amount of 515.6 kg / h. The reaction mixture from the reactor 5 is cooled in the heat exchanger 8, the condenser-cooler 11, and in the separator 12, the methanol is separated from the synthesis gas. The noncondensable gas stream is heated in 13 reaction products from 6 and fed to a reactor 6 in which methanol is produced at a pressure of 6.4 MPa and a temperature of 210 ° C. in an amount of 176.5 kg / h . The composition of the reactants at the inlet to the reactor 6 is as follows: hydrogen 23.1 vol.% , Carbon monoxide 11.51 vol.% , Carbon dioxide 2.44 vol. The gas-vapor mixture of reaction products of reactor 6 is cooled in heat exchanger 13, condenser-condenser 14, and methanol is separated from reaction products in separator 15. Non-condensable gas components of composition: hydrogen 18.44% by volume , carbon monoxide 9.2% , Carbon dioxide 2.69% by volume after heating in the heat exchanger 16 are fed to the catalytic reactor 7 in which, at a pressure of 6.3 MPa and a temperature of 210 ° C., 57.48 kg / h of methanol are formed. The total amount of methanol produced for the consumer is 644.62 kg / h . The composition of the obtained product methanol: water - 2.2 wt. % , Methanol - 97.8% by weight , organic impurities in trace amounts. "Tail gases" are sent to a gas turbine for power generation.

Example 3
1002 m 3 / h of natural gas and oxidizer (air) are supplied to the power machine (gas turbine, internal combustion engine) or catalytic reactor. 5,500 m 3 / h of synthesis gas is formed: hydrogen - 26,8% by volume , carbon oxide - 14,3% by volume , carbon dioxide - 3,56% by volume , methane - 1,29 % by volume. % , Nitrogen - 54.05% vol . Synthesis gas is compressed into 2 and in reactor 3 it is cleared of possible small amounts of oxygen in it. In the mass exchange apparatus 20, the permeate stream is enriched with hydrogen and the retentate stream is depleted. A portion of methanol produced in the reactors 5, 6, 7 in an amount of 100 kg / h is subjected to a steam reforming reaction in the reactor 4 and the resulting hydrogen is fed to the feed of the synthesis gas. Prepared synthesis gas of the composition : hydrogen - 32.44% vol. , Carbon monoxide - 14.62% , carbon dioxide - 3.56% , methane - 1.13% , nitrogen - 48.23 % .% Is sent to a catalytic reactor 5 in which methanol is produced at a pressure of 6.5 MPa and a temperature of 200 ° C. in an amount of 522.2 kg / h . The reaction mixture from the reactor 5 is cooled in the heat exchanger 8, the condenser-cooler 11, and in the separator 12, the methanol is separated from the synthesis gas. The noncondensed gas stream is heated in 13 reaction products from 6 and fed to a reactor 6 in which methanol is produced at a pressure of 6.5 MPa and a temperature of 210 ° C. in an amount of 242.2 kg / h . The gas-vapor mixture of reaction products of the reactor 6 is cooled in the heat exchanger 13, the condenser-condenser 14, and the methanol is separated from the reaction products in the separator 15. The non-condensable gas components, after being heated in the heat exchanger 16, enter the catalytic reactor 7, at a pressure of 6.5 MPa and a temperature 220.degree . C., 89.1 kg / hr of methanol are formed. The total amount of product methanol produced for the consumer is 853.5 kg / h . The "tail gas" of the reactors 5, 6, 7, combined with the retentate stream and the natural gas stream, is sent to the gas turbine 21 to generate electricity. The vapor formed in the intertubular space of the catalytic reactors and further heated by the heat of the turbine discharge gases is sent to the steam turbine 23 for additional power generation.

CLAIM

  1. A process for the production of methanol, comprising the step of producing synthesis gas from gaseous hydrocarbons, a synthesis gas compression step, a catalytic conversion step of the synthesis gas to methanol in a reactor assembly consisting of several catalytic reactors, comprising the steps of heating and conversion of the synthesis gas in each reactor, The operation of cooling the reaction products and recovering the produced methanol after each reactor, a tail gas recovery operation characterized in that hydrogen obtained after vapor conversion of a part of the produced methanol is mixed with the synthesis gas to form a prepared synthesis gas with a molar ratio of hydrogen to oxide Carbon in the interval 1.4: 1 and 3: 1 and it is fed to the reactor unit for the catalytic conversion of synthesis gas to methanol.

  2. The method according to claim 1, characterized in that the catalytic conversion of the synthesis gas to methanol is carried out in a temperature range of 160-320 ° C , pressures of 4.0-10.0 MPa , and volumetric rates of 500-5000 h -1 .

  3. The method according to claim 1, characterized in that the production of the synthesis gas is carried out at a molar ratio of oxygen: gaseous hydrocarbons of less than 0.7 .

  4. The method according to any one of claims 1 to 3, characterized in that the production of hydrogen by a steam conversion of methanol is carried out in a temperature range of 120-320 ° C , pressures of 0.1-10.0 MPa , volumetric flow rates of 200-10000 h -1 .

  5. A process according to any one of claims 1 to 4, characterized in that the oxygen content in the synthesis gas entering the catalytic methanol reactors is up to 1.0 volume% .

  6. A method according to any one of claims 1 to 5, characterized in that the prepared synthesis gas is fed sequentially, periodically to each of the reactors in the methanol synthesis reactor unit with continuously operating the remaining reactors.

  7. The process according to any one of claims 1 to 6, characterized in that the synthesis gas is divided into two streams, one of which is mixed with hydrogen in a membrane-type mass transfer plant and fed to the methanol synthesis reactor unit, and the second hydrogen-depleted stream is mixed with A gas stream leaving the last catalytic methanol synthesis reactor and gaseous hydrocarbons, and the mixture is sent to a power and / or heat plant as a gas fuel.

print version
Date of publication 05.12.2006гг