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INVENTION
Patent of the Russian Federation RU2152378
METHOD OF OBTAINING METHANOL
The name of the inventor: Pisarenko VN; Abasculiev DA; Chernomyrdin A.V .; Kachalov VV; Brezgin B.E.
The name of the patent holder: Closed Joint-Stock Company "FIRMA RUSINVEST"
Address for correspondence: 103498, Moscow, K498, Birch Alley, к.423, кв.81, Kremlin V.Ya.
Date of commencement of the patent: 1999.04.28
The process for producing methanol comprises the step of producing a synthesis gas, a step of catalyzed conversion of synthesis gas to methanol in a series of connected reactors, comprising the steps of supplying and heating the synthesis gas in the inlet zones of the reactors with an external coolant, the catalytic conversion of the synthesis gas to methanol with gas stream heating Due to the heat from the gas stream in the outlet zone of the reactor, the methanol recovery operation and tail gas recovery. The method is characterized in that synthesis gas containing more than 40 vol.% Nitrogen is supplied to the inlet zones of the reactors at a molar ratio of hydrogen to carbon monoxide in the range 2.8: 1 to 1.8: 1, heating the gas stream to the coolant temperature in Inlet zones of the reactor is carried out with a temperature gradient along the length of the reactor exceeding the gradient of the temperature of the gas stream heating in the active part of the reactor due to the reaction heat. For example, the process of methanol synthesis is carried out in the temperature range of 170 - 280 o C, pressure of 4,0 - 10,0 MPa and volumetric flow rates of 1000-10,000 h -1 , heating of the gas flow to the coolant temperature in the inlet zones of the reactor is carried out with a temperature gradient not More than 10 ° C / dm, and the temperature gradient of the gas stream heating in the active part of the reactor is no more than 3 ° C / dm.
DESCRIPTION OF THE INVENTION
The invention relates to energy-saving methods for synthesizing methanol from synthesis gas obtained by partial oxidation of natural gas with air enriched with oxygen, air, or in oxygen-containing gas streams with a high nitrogen content in power machines with generation of electricity at all stages of methanol production.
More particularly, the invention relates to the field of chemical-technological, energy-saving processes for the production of methanol from natural gas or "tail" hydrocarbon-containing gases of chemical, petrochemical and metallurgical industries.
In conventional methanol production processes, usually the first stage of the process is to produce synthesis gas by steam methane conversion. At this stage, the total conversion of methane to synthesis gas is not achieved, and therefore the residual methane is converted in a subsequent stage - the steam-oxygen conversion (possibly combining these stages). Oxygen conversion usually uses pure oxygen or oxygen-enriched air, the production of which is associated with energy costs. In addition, steam carbon monoxide conversion processes are carried out to increase the hydrogen content in the synthesis gas and recover additional carbon dioxide from the synthesis gas. The cost price of the obtained synthesis gas containing a small amount of nitrogen is high enough that the produced synthesis gas could be used, in addition to methanol production, even in the production of olefins or motor fuels. The reaction of methane vapor conversion is highly endothermic and, along with the methane steam-oxygen conversion, is carried out in expensive equipment with significant energy and operating costs.
There are known technologies for the production of synthesis gas from natural gas (see US Patent 5.177.114), the cost of which is significantly lower compared to the cost of synthesis gas produced by traditional technologies. This is achieved primarily due to the fact that synthesis gas is obtained as a result of partial oxidation of natural gas. And as an oxidizer is used not oxygen, but air or air enriched with oxygen. The cost reduction is achieved due to:
1) lower costs for the production of oxygen-enriched air compared to the costly production of pure oxygen;
2) use of simpler and less expensive equipment;
3) lower operating costs;
4) use of simpler and cheaper process control systems.
The disadvantages of the process under consideration include the need to produce a synthesis gas containing significant amounts of nitrogen, up to (40 vol.%). Therefore, the production of methanol or motor fuels, or key products of petrochemical synthesis, should be carried out on a no-recirculation scheme, otherwise the prime cost of the target products would again increase due to the recycling of large flows of inert components (nitrogen, methane). Thus, the shortcomings of the existing schemes for processing natural gas are the complexity of the technological design process, the use of a large number of units of process equipment, and the lack of flexibility of technological schemes for raw materials.
In German patent DE 4300017 A1, low-concentration hydrocarbon-containing gases are processed into methanol. However, with a low quality of the methanol produced and without the use of heat from chemical reactions and heat from the exhaust gases, the cost of the target product will be high enough, and the installation will not be energy-tight. The latter circumstance will restrain its use in various areas of industry.
The method closest to the claimed process for the production of methanol selected as a prototype is the method described in the patent (US 5,472,986). In the prototype method, synthesis gas with a high nitrogen content is converted, with an intermediate exit of the methanol produced in the reactors after each catalytic reactor.
The main drawback of the invention adopted for the prototype is that the heat of the partial oxidation of methane and methanol synthesis is not used to generate electricity, which does not significantly improve the efficiency of the operation (and, therefore, reduce the cost of the target product - methanol) of industrial plants of this type. In addition, synthesized methanol contains a large amount of water and organic impurities, which requires a fairly complex rectification system to produce the high purity target product. Therefore, the energy costs of the separation increase and increase compared to the separation of reaction products that do not contain significant amounts of by-products.
Thus, the analysis of known methanol production technologies shows that there are no energy-tight methanol synthesis plants that would be characterized by obtaining the desired product - methanol - of high quality.
The present invention poses the following tasks: improving the quality of the target product, methanol produced by conversion of natural gas, and transforming the heat of chemical reactions at all stages of the chemical conversion of the reactants into electrical energy ensuring the closure of the industrial methanol synthesis plant for energy, and simplifying the methanol production process scheme , Reduction of capital and energy costs.
These problems are solved in a process for producing methanol comprising the step of converting the hydrocarbonaceous feedstock to synthesis gas, the step of catalytic conversion of the synthesis gas to methanol in a series of connected reactors including the steps of feeding and heating the synthesis gas in the inlet zones of the reactors with an external coolant, Gas into methanol with heating of the gas stream due to the heat of methanol synthesis reactions in the active part of the reactor, heat removal from the gas stream in the reactor outlet zone, methanol recovery and tail gas utilization in which syngas is fed to the inlet zones of the reactors, Containing more than 40 vol. % Of nitrogen, at a molar ratio of hydrogen to carbon monoxide in the range from 2.8: 1 to 1.8: 1, the heating of the gas stream to the temperature of the coolant in the inlet zones of the reactor is carried out with a temperature gradient along the length of the reactor exceeding the temperature gradient of the gas stream heating in Active part of the reactor due to the reaction heat.
The difference in the methanol production process is that synthesis gas is introduced into the inlet zones of the reactors, containing more than 40 vol. % Nitrogen, at a molar ratio of hydrogen to carbon monoxide in the range from 2.8: 1 to 1.8: 1, heating of the gas stream to the coolant temperature in the inlet zones of the reactor is carried out with a temperature gradient along the reactor length exceeding the temperature gradient of the gas stream heating in Active part of the reactor due to heat reactions.
A second variant of the process for the production of methanol is characterized in that the methanol synthesis process is carried out in a temperature range of 170-280 ° C, with a pressure of 4.0-8.0 MPa and a flow rate of 500-10000 h -1 .
A third variant of the process for producing methanol is characterized in that the heating of the gas stream to the coolant temperature in the inlet zones of the reactors is carried out with a temperature gradient of no more than 10 ° C./dm, the temperature gradient of the gas stream in the active part of the reactor being no more than 3 ° C./dm .
A fourth variant of the process for producing methanol is characterized in that the starting synthesis gas is divided into two streams, one of which is enriched with hydrogen in a membrane-type mass transfer apparatus and fed to the first catalytic reactor, thereby adjusting the ratio of hydrogen to carbon monoxide, and the second hydrogen-depleted stream , Is mixed with a gas stream leaving the last catalytic reactor after the methanol evolution and the mixture is fed to the gas turbine as a fuel, ensuring complete combustion of the fuel.
A fifth variant of the process for producing methanol is characterized in that the steam produced by the heat of the methanol synthesis reaction is fed to a steam turbine to produce electricity, and the tail gas is utilized in gas turbines to produce electricity.
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In Fig. 1. The essence of the proposed invention is illustrated which assumes the use of a methanol production unit consisting of three series-connected reactors 1, 2, 3. Each of them has an entrance zone 4, a main catalytic reaction zone 5, an outlet zone 6. The outlet zones are connected to the separators 7 , 8, 9, and they - with heat exchangers 10, 11. Compressor 13 and heat exchanger 12 are located at the entrance to the plant (Fig. 1.). |
In Fig. 2. Diagrammatically depicts an energy-saving plant for the production of methanol in accordance with Nos. 4, 5 of the claims. The plant further comprises a membrane apparatus 14, a steam turbine 15, a steam and gas stream heating furnace 16, a gas turbine 17.
The energy-chemical method for producing methanol is realized in the apparatus shown in FIG. 1,2, as follows.
The feedstock-synthesis gas with a space velocity of 500-10,000 h -1 (obtained by partial oxidation of natural gas in internal combustion engines, gas turbines or catalytic reactors) is fed to compressor 13, where it is, for example, compressed to a pressure of 6.0 MPa. Then it is sent to the heat exchanger 12 where it is heated by the product streams of the 1st reactor to a temperature close to the reaction temperature for methanol production. After the heat exchanger 12, the synthesis gas enters the inlet zone 4 of the reactor 1. In it, it is heated to a temperature of the heat carrier with a temperature gradient of no more than 10 ° C / dm. As a heat carrier, for example, water can be used. Further, the gas stream passes through zone 5 of reactor 1 in which the main conversion of synthesis gas to methanol occurs and zone 6 of reactor 1. In zone 5 of reactor 1, the gas stream is heated by the heat of a chemical reaction at a temperature gradient along the reactor axis not exceeding 3 ° C / dm. In zone 6 of reactor 1, the gas flow is cooled and the temperature gradient along the reactor axis is negative.
From the reactor 1, the gas stream passes the heat exchanger 12, where it heats the feedstock to a temperature close to the temperature in the reactor 1. It then enters the separator 7 where methanol is condensed and the non-condensable gases pass through the heat exchanger 10 to the inlet zone 4 of the reactor 2.
The operating conditions of the reactors 2 and 3 are similar to those of the reactor 1. From the reactor 3, a gas product stream is fed to a separator 9 where liquid methanol synthesis reaction products condense and non-condensable gases are fed to the tail gas utilization unit (shown in FIG.
Variant of methods, corresponding to pp. 4, 5, is carried out as follows. The raw material, a synthesis gas with a high nitrogen content, is fed into the compressor, which receives a hydrogen-rich synthesis gas stream from the membrane apparatus 14. A part of the syngas stream from the compressor 13 enters the membrane apparatus. In it, the gas stream 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.
Complemented in the compressor 13, the hydrogen-rich feed stream passes three successive connected reactors to form methanol in each of them (similar to the scheme shown in Fig. 1). The unreacted synthesis gas from the separator 9 is combined with a retentate stream and sent to the gas turbine 17 as a gas fuel for power generation. The flue gases of the turbine 17 enter the furnace 16 to heat the steam from the reactors 1, 2, 3. The superheated 16 steam enters the steam turbine to generate electricity.
The above examples do not exhaust all possible implementations of the methanol preparation process.
Consequently, the physicochemical meaning of the proposed invention is that methanol synthesis is carried out in a nitrogen medium (with a content of more than 40% by weight) under given temperature regimes of the reactors ensuring a highly selective flow of the process due to homogeneity of the heat fluxes and absence both in the reactor, And the catalyst grain of zones with a high content of reactants.
The invention is illustrated by the following specific embodiments of the method.
Example 1 . 1002 m 3 / h methane and an oxidizer (air) are supplied to the power machine (gas turbine). Excess oxidizer coefficient 0.35. There is formed 5,400 m 3 / h synthesis gas of composition: H 2 - 27 vol. %, CO - 1.4 vol. %, N 2 - 52 vol. %, CO 2 - 3 vol. % At 1000 m3 of pure synthesis gas (without nitrogen), over 0.3 MW of electricity is generated.
The resulting synthesis gas (FIG. 2) is fed to a catalytic reactor 1 in which methanol of 486 kg / h is synthesized at a pressure of 6.5 MPa and a temperature of 200 ° C. The reaction mixture at the outlet of 1 is cooled in the heat exchanger 12 and methanol is separated in the separator 7. The non-condensed gas stream is heated by the reaction products from 2 to 205 ° C. and fed to the catalytic reactor 2 in which, at a pressure of 6.5 MPa and a temperature of 210 ° C., Methanol in an amount of 178.2 kg / h. The composition of the reactants at the inlet to 2 is as follows: H 2 - 18.1 vol. %. CO is 9.66 vol. %, CO 2 - 4.0 vol. % The steam-gas mixture of reaction products from 2 is cooled in heat exchanger 10 and methanol is separated from the reaction products in separator 8. Non-condensable gas components of composition: H 2 - 13.19 vol. %, CO - 7.26 vol. %, CO 2 - 4.5 vol. % After heating in the heat exchanger 11 is fed to the catalytic reactor 3 in which, at a pressure of 6.5 MPa and a temperature of 210 ° C., 83.2 kg / h of methanol are formed. After the cooling of the gas mixture in the heat exchanger 11, it is separated in the separator 9.
The total amount of methanol produced is 747.4 kg / h. The composition of the resulting methanol: water 1.5% by weight, methanol 98.5% by weight. The content of other reaction products (dimethyl ether, formates, ethanol) in trace amounts. In the catalytic reactors 1, 2, 3, in particular, a copper-zinc catalyst of the SNM-1 type is used.
The catalytic reaction for the synthesis of methanol in reactors 1, 2, 3 with a catalyst volume of 1150 liters in each is carried out with temperature gradients in the inlet zones of the reactors below 10 o C / dm and temperature gradients in the reactor zones of less than 3 o C / dm. At the same time, due to the heat of chemical reactions, more than 0.07 MW of electricity was produced in the steam turbine.
"Tail" gases of catalytic reactors are sent to a gas turbine. At the same time, more than 0.9 MW of electricity is generated.
Example 2 . In the power machine, due to the partial oxidation of 1005 m 3 / h of natural gas, 5,400 m 3 / h of synthesis gas is obtained: hydrogen 37.2% %, Carbon monoxide - 18.5% vol. %, Carbon dioxide 3.0 vol. %, Methane - 1.5 vol. %, The balance is nitrogen.
The resulting synthesis gas (the total molar flux is 241.07 × 10 3 mol / h) is fed to the first catalytic reactor. The pressure in the reactor is 1 7.0 MPa, the temperature is 220 ° C. The molar stream at the outlet of 1 is hydrogen: 42.84 × 10 3 mol / h, carbon monoxide 21.18 × 10 3 mol / h, carbon dioxide 7.13 × 10 3 Mol / h, methanol - 23.42 × 10 3 mol / h, inertia - 99.6 × 10 3 mol / h. After cooling and condensation from the gas of methanol and water, the non-condensable gas components are supplied after preheating in the heat exchanger 10 to the catalytic reactor 2. The gas inlet velocity in P-2 is 3836 m 3 / h, the pressure in P-2 is 7.0 MPa, 220 ° C. The molar streams of the components at the outlet of 2 are: hydrogen = 21.80 × 10 3 mol / h, carbon monoxide 10.66 × 10 3 mol / h, carbon dioxide = 6.7 × 10 3 mol / h, inertia = 99.8 × 10 3 mol / h. After cooling, condensation of methanol and water, uncondensed gases are fed into 3. The volumetric feed rate of the feed is 3107.3 m 3 / h. The pressure is 3-6.9 MPa, the temperature is 220 o C. The molar gas flows at the outlet of 3: hydrogen is 13.22 × 10 3 mol / h, carbon monoxide is 6.37 × 10 3 mol / h, carbon dioxide is 5.86 × 10 3 mol / H, methanol - 4.29 × 10 3 mol / h, inertia - 100.25 × 10 3 mol / h.
The total amount of methanol produced is 1223.2 kg / h, the mass content of water in the liquid reaction products is 2.5% by weight. Catalytic reactors 1, 2, 3 use, in particular, a copper-zinc catalyst of the SNM-1 type.
The operation of all catalytic reactors 1, 2, 3 with a catalyst volume of 1150 liters in each was carried out at temperature gradients in the inlet zones of reactors 1, 2, 3 below 10 ° C / dm, temperature gradients in the active zones of reactors 1, 2, 3 less than 3 O C / dm
Example 3 . In the power machine, a partial oxidation of 1002 m 3 / h of natural gas is carried out. Composition of the produced synthesis gas: hydrogen - 30.05. %, Carbon monoxide - 17.41%. %, Carbon dioxide - 2.03g. %, The rest - inert components - nitrogen and methane.
4608 m 3 / h synthesis gas is fed to a catalytic tubular reactor containing 288 tubes. The volume of catalyst in each tube of the reactor is 4 dm 3 . The pressure in the reaction zone of the reactor is 8.0 MPa, the temperature is 220 ° C. The amount of liquid reaction products obtained is 708.8 liters. The content of methanol in the catalyst is 92 wt. %, The rest is water. The temperature gradient in the inlet zone of the reactor is less than 10 o C / dm, the temperature gradient in the reactor core is less than 3 o C / dm. Catalytic reactors 1, 2, 3 use, in particular, an ICI copper-zinc catalyst.
Example 4 . In the power machine, a partial oxidation of 1002 m 3 / h of natural gas is carried out. The composition of the produced synthesis gas: hydrogen is 31.0 vol. %, Carbon monoxide - 16.2 vol. %, Carbon dioxide - 2.03 vol. %, The rest - inert components - nitrogen and methane.
4840 m 3 / h synthesis gas is fed to a catalytic tubular reactor containing 288 tubes. The volume of catalyst in each tube of the reactor is 4 dm 3 . The pressure in the reaction zone of the reactor is 6.5 MPa, the temperature is 220 ° C. The amount of liquid reaction products obtained is 662.4 liters. The content of methanol in the catalyst is 94.5 mas. %, The rest is water. The temperature gradient in the inlet zone of the reactor is less than 10 o C / dm, the temperature gradient in the reactor core is less than 3 o C / dm. Catalytic reactors 1, 2, 3 use, in particular, an ICI copper-zinc catalyst.
Example 5 . In the power machine, partial oxidations of 1020 m 3 / h of natural gas are carried out. The composition of the obtained synthesis gas: hydrogen is 29 vol. %, Carbon monoxide - 16.0 vol. %, Carbon dioxide 3.0 vol. %, The rest - inert components - nitrogen and methane. The total molar flow of synthesis gas is 241.07 × 10 3 mol / h, the reactant streams: hydrogen is 69.9 × 10 3 mol / h, carbon monoxide is 38.57 × 10 3 mol / h, carbon dioxide is 7.23 × 10 3 mol / h. The synthesis gas stream is directed to the membrane element, in which it is divided into permeate and retentate streams. The permeate flux is 4.640 m 3 / h (molar reactant streams: hydrogen - 64.2 × 10 3 mol / h, carbon monoxide - 29.41 × 10 3 mol / h, carbon dioxide - 6.42 × 10 3 mol / h). The retentate flow is 760 m 3 / h (molar reactant streams: hydrogen - 5.7 × 10 3 mol / h, carbon monoxide - 9.16 × 10 3 mol / h).
The retentate stream is directed to the gas turbine, and the permeate stream enriched in hydrogen to the catalytic reactor 1 (FIG. 2). In it, at a temperature of 205 ° C, a pressure of 7.0 MPa, 489 kg / h of methanol is formed, which is separated in the separator 7 from the gas stream. The molar flows of the synthesis gas components entering the reactor 2 are as follows: hydrogen 33.62 × 10 3 mol / h, carbon monoxide 14.15 × 10 3 mol / h, carbon dioxide 6.11 × 10 3 mol / h. In reactor 2 at a pressure of 7.0 MPa, at a temperature of 205 ° C., 158.5 kg / h of methanol are formed. After its separation in the separator 8, the synthesis gas is fed to the reactor 3. The molar reactant streams entering the reactor 3: hydrogen 23.72 × 10 3 mol / h, carbon monoxide 9.2 × 10 3 mol / h, carbon dioxide 6.13 × 10 3 mol / h. In it at a pressure of 7.0 MPa, at a temperature of 210 ° C., 83.4 kg of methanol are formed. The total amount of methanol produced in three reactors is 730.9 kg / h.
The unreacted synthesis gas is mixed with the retentate stream and fed to a gas turbine. At the same time, more than 1.2 MW of electricity is generated in the gas turbine.
Catalytic reactors use, in particular, an ICI type catalyst.
The catalytic reaction for the synthesis of methanol in reactors 1, 2, 3 with a catalyst volume of 1150 liters in each is carried out with temperature gradients in the inlet zones of the reactors below 10 ° C / dm and temperature gradients in the reactor core less than 3 ° C / dm. Due to the heat of chemical reactions, more than 0.07 MW of electricity was produced in the steam turbine.
Example 6 . In the power machine, a partial oxidation of 1002 m 3 / h of natural gas is carried out. Composition of the produced synthesis gas: hydrogen - 31.0 vol. %, Carbon monoxide - 16.2 vol. %, Carbon dioxide - 2.03 vol. %, The rest - inert components - nitrogen and methane. The change in the temperature conditions of the operation of the reactors and the process parameters are shown in Table. 1
Example 7 . In the power machine, a partial oxidation of 1002 m 3 / h of natural gas is carried out. Composition of the produced synthesis gas: hydrogen - 38.1 ob. %, Carbon monoxide - 18.4 vol. %, Carbon dioxide - 2.03 vol. %, The rest - inert components - nitrogen and methane. The change in the composition of nitrogen in the synthesis gas and the process parameters are shown in Table. 2.
CLAIM
A process for the production of methanol, comprising the step of producing synthesis gas, a step of catalytically converting the synthesis gas to methanol, comprising the steps of supplying and heating the synthesis gas in the inlet zones of the reactors, the catalytic conversion of the synthesis gas to methanol with the heating of the gas stream by heat Methanol synthesis, methanol recovery and tail gas recovery, characterized in that the process is carried out in a series of reactors connected in series, heating the synthesis gas containing more than 40 vol.% Nitrogen at a molar ratio of hydrogen to carbon monoxide in the range of 1.8: 1 to 2.8: 1 in the inlet zones of the reactors by an external coolant to the coolant temperature is carried out with a temperature gradient along the length of the reactor exceeding the temperature gradient of the gas stream heating in the active part of the reactor due to the reaction heat with heat removal in the exit zones of the reactors .
2. A process for the preparation of methanol according to claim 1, wherein the synthesis of methanol is carried out in a temperature range of 170 to 280 ° C, with a pressure of 3.0 to 8.0 MPa and a flow rate of 500 to 10,000 h -1 .
3. A process for the production of methanol according to claims 1 and 2, characterized in that the heating of the gas stream to the temperature of the coolant in the inlet zones of the reactors is carried out with a temperature gradient of no more than 10 ° C./dm, and the temperature gradient of the gas stream in the active part of the reactor is Not more than 3 o C / dm.
4. Process for producing methanol according to claims 1 to 3, characterized in that the starting synthesis gas is divided into two streams, one of which is enriched with hydrogen in a membrane-type mass transfer unit and fed to the first catalytic reactor, adjusting the ratio of hydrogen to carbon monoxide , And the second hydrogen-depleted stream is mixed with the tail gas stream leaving the last catalytic reactor after the methanol evolution and the mixture is sent for recycling to a gas turbine as fuel.
5. Method for producing methanol according to claims 1 to 4, characterized in that the tail gas is utilized by supplying it to a gas turbine with electricity generation.
print version
Date of publication 07.04.2007gg
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