RU2548410C2 - Method and device for syngas production - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: group of inventions relates to hydrocarbon (HC) feed stock (CH₄) processing, i.e. method and device (reactor) for syngas production. Method of syngas production by the methane catalytic transformation by the chemicals passage through the fixed bed of catalyst; the ring bed of catalyst is used as fixed bed of catalyst, in it the chemicals pass from internal to outside surface of the ring bed of catalyst; the methane mixture with gaseous chemicals is used as chemicals, the mixture additionally contains products of plasmochemistry desintegration of the gaseous chemicals or their mixture; thermal mode of the process is ensured by mixing of the products of plasmochemistry disintegration with mixture of methane and gaseous chemicals; and at least part of chemicals is directly supplied to the plasmochemistry zone. At that carbon dioxide or water vapour, or oxygen are used as gaseous chemicals. The reactor for the syngas production by the methane catalytic transformation including the fixed bed of catalyst and device for chemicals and catalyst heating is made in form of a ring, in which chemicals move from internal to outside surface of the ring bed of the catalyst, the device for chemicals and catalyst heating is made in form of the plasmatron using the work gas and located in centre of the reactor in the plasmochemistry zone, it has fireproof heat insulation; between the plasmochemistry zone and the catalyst bed there is buffer zone in which the chemicals and products of the disintegration of the plasmatron work gas are mixed. Besides the plasmatron can be made with possibility of movement in the plasmochemistry zone.

EFFECT: invention ensures capacity increasing of the syngas production and reduces heat losses to environment.

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Description

Technical field

The present group of inventions relates to the field of hydrocarbon processing (CH ₄ ) - to a method and apparatus (reactor) for producing synthesis gas. Synthesis gas (CO + H ₂ ) is used in the synthesis of methanol, dimethyl ether, the production of hydrocarbons by the Fischer-Tropsch method, etc.

State of the art

The main methods for producing synthesis gas are based on the oxidative conversion of methane:

- methane steam reforming (PFP):

СН + Н ₂ О = СО + 3Н ₂ ΔН = + 206 kJ / mol

- partial oxidation of methane (POM) with oxygen:

СН ₄ + ½О ₂ = СО + 2Н ₂ ΔН = -35.6 kJ / mol

- carbon dioxide methane reforming (URM):

CH ₄ + CO ₂ = 2CO + 2H ₂ ΔH = + 247 kJ / mol

At least two of these processes: steam reforming and carbon dioxide reforming require significant energy costs due to the endothermic nature of the course. To obtain synthesis gas by the above methods, practically only the methane steam reforming method is used in industry. The process is carried out on a supported Ni catalyst at a high temperature (700-900 ° C). In addition, all of the above processes occur with increasing pressure (at a constant volume). Therefore, the organization of optimal heat transfer and pressure stabilization in the catalyst bed are one of the urgent tasks of developing new methods and designs of reactors for these processes.

The prior art method for producing synthesis gas by carbon dioxide reforming of methane in a flow reactor is described in patent RU 2325219, published May 27, 2008, in which at a temperature of 1073 K, a pressure of 1 atm on a bulk catalyst system Ni / Al ₂ O _{3 it is} possible to achieve conversion methane and CO ₂ about 96% with a ratio of H ₂ : CO about 0.96. A significant drawback of this process is the rapid deactivation of the catalyst due to the high proportion of coke formation processes.

There is also known a method for producing synthesis gas by carbon dioxide reforming of methane on a porous ceramic catalytic module (PKKM), disclosed in patent RU 2325219, published May 27, 2008, which is a thermal synthesis product of a highly dispersed exothermic mixture of nickel and aluminum densified by vibrocompression. PKKM contents (% wt.): Ni - 56-96; Al 4-44. PKKM may additionally contain titanium carbide in an amount of 20% of the mass. in relation to the mass of the module, as well as a catalytic coating comprising La and MgO or Ce and MgO, or La, Ce and MgO, or ZrO ₂ , Y ₂ O ₃ and MgO, or Pt and MgO, or W ₂ O ₅ and MgO in the amount of 0.002-6 mass. % in relation to the mass of the module. Synthesis gas is obtained by converting a mixture of methane and carbon dioxide at a temperature of 450-700 ° C and a pressure of 1-10 atmospheres in a filtration mode on a PCCM at a feed rate of methane and carbon dioxide through a module of 500-5000 h ^-1 . The disadvantage of this method is the increased coke formation, which reaches 79.5%.

Closest to the claimed method is the method for producing synthesis gas described in published on March 27, 2009 patent RU 2350386 in the processes of partial oxidation of methane, steam reforming of methane and carbon dioxide reforming of methane by passing reactants through a fixed catalyst bed at a temperature of 800-1200 ° C, pressure 1 -7 bar and a volumetric rate of transmission of reagents 5000-15000 h ^-1 .

According to the prototype process is carried out as follows. Partial oxidation of methane by oxygen is carried out at a temperature of 600-850 ° C and a space velocity of 5000 h ^-1 . The composition of the reaction mixture at the inlet to the reactor (% vol.): CH ₄ - 20; O ₂ - 10; Ar - 70. Ni / Al ₂ O ₃ promoted with U compounds is used as a catalyst. The best results achieved are:

methane conversion,% 94 yield H ₂ ,% 93 CO yield,% 93

Steam reforming of methane is carried out at a temperature of 600-850 ° C and a space velocity of 6300 h ^-1 . The composition of the reaction mixture at the inlet to the reactor (% vol.): CH ₄ - 15; H ₂ O - 45; Ar - 40. Ni / Al ₂ O ₃ promoted with U compounds is used as a catalyst. The best results achieved are:

methane conversion,% 80 yield H ₂ ,% 42 yield Co,% 27

Carbon dioxide reforming of methane is carried out at 850 ° C and a space velocity of 5000 h ^-1 . The composition of the reaction mixture at the inlet to the reactor (% vol.): CH ₄ - 20; CO ₂ - 20; Ar - 60. Ni / Al ₂ O ₃ promoted with U compounds is used as a catalyst. Under these conditions, it is possible to achieve a methane and CO ₂ conversion _of about 95% with an H ₂ : CO ratio of about 0.95. Modification of the catalyst by uranium compounds significantly reduces coke formation: the carbon yield is only 0.4% versus 14% using unmodified Ni / Al ₂ O ₃ - catalyst.

The disadvantage of the prototype is the low productivity of the methods described in it, due to the fact that the process proceeds in the filtering mode provided by the ceramic catalytic membrane.

The prior art various devices for producing synthesis gas, the design features of which are due, first of all, to the method of heat input in catalytic reactors with the occurrence of endothermic reactions, among which there are two main methods:

1) supply of the body from external sources;

2) heat supply due to exothermic reactions occurring in the reaction system itself (the so-called “internal heating”).

Reforming with "internal heating" was called autothermal reforming (APR). It is usually sold through internal combustion of a portion of the process gas. As an oxidizing agent, ATP schemes use oxygen rather than air to eliminate the harmful effects of nitrogen and inert gases. This type of reforming is currently considered one of the most effective in terms of cost and effectiveness among the methods of production of synthesis gas. In ATP, light hydrocarbon feeds with the addition of water vapor react with a near-stoichiometric amount of oxygen to produce synthesis gas. The prior art, for example, operates under pressure an ATP reactor described in patent RU 2345948, published March 20, 2010, which consists of a burner, a combustion chamber and a catalyst layer in a casing coated with a refractory. A similar solution is proposed in patent RU 2342318, published December 27, 2008.

An externally heated reactor is disclosed in patents: RU 2354607, published May 10, 2009, and RU 2354608, published May 10, 2009. In these patents, the reforming process takes place in three different devices — an adiabatic pre-reforming unit, structured catalytic elements with steam reforming catalysts, and in a tubular reformer with fire heating. Similar technical solutions were proposed by Lurga and One Synergy, in which steam reforming involves heating the catalytic zone by convection of combustion products. As a result of the pre-reforming process, traces of higher hydrocarbons that may be present in natural gas are removed.

The prior art reactor is described in patent RU 921621, published 04/23/1982, in which the catalyst is placed in rectangular cassettes with upper open ends fixed in a horizontal partition and equipped with removable gratings placed on their lower ends.

In addition, according to patent RU 1431825, published on 10.23.1988, a conversion element is known in which, to intensify the external heat exchange supplied to the tubes containing the catalyst, the outer surface of the tubes is made in the form of corrugations. The corrugations of the surface perform the functions of radial finning and provide the intensification of heat transfer processes from the heating medium.

The closest set of essential features to the claimed device is the reactor described in patent RU 2350386, published March 27, 2009, which is a cylinder made of heat-resistant material (quartz) with a fixed catalyst bed located inside. The cylinder is placed in a tube furnace and heated to the reaction temperature.

The disadvantage of this device is its large heat loss to the environment associated with the external location of the heat supply zone in relation to the reaction catalytic zone. The constancy of the elemental volume of the catalyst with respect to the finished reagent stream leads to an increase in pressure in this elementary volume and a decrease in the rate of chemical reactions.

Disclosure of invention

The technical result achieved by using the claimed group of inventions is to increase the productivity of the process of producing synthesis gas and reduce heat loss to the environment.

The specified technical result is achieved due to the fact that in the method for producing synthesis gas by catalytic conversion of methane by passing reactants through a fixed catalyst bed, an annular catalyst layer is used as a fixed catalyst layer, in which the reactants are passed from the inner to the outer surface of the annular catalyst layer, as reagents use a mixture of methane with gaseous reagents, additionally containing products of plasmachemical decomposition of gaseous p agents, or mixtures thereof, the heat treatment process is obtained by the mixing of plasma chemical decomposition products with a mixture of methane with the gaseous reactants and at least part of the reactants fed directly into plazmohimicheskim zone. In this case, carbon dioxide or water vapor or oxygen is used as gaseous reactants.

The specified technical result is achieved due to the fact that in the reactor for producing synthesis gas by catalytic conversion of methane, including a fixed catalyst bed and a heating device for the reactants and catalyst, the catalyst layer is made in the form of a ring in which the movement of the reactants is carried out from the inner to the outer surface of the annular the catalyst bed, the heating device of the reactants and the catalyst is made in the form of a plasmatron consuming the working gas and located in the central part of the reactor in the plasma In the chemical zone with refractory thermal insulation, a buffer zone is located between the plasma chemical zone and the catalyst layer, in which the reagents and plasma chemical decomposition products of the plasmatron working gas are mixed. In addition, the plasmatron can be made with the possibility of movement in the plasma-chemical zone.

Brief Description of the Drawings

Figure 1 presents a schematic diagram of a reactor in which a method for producing synthesis gas is implemented.

The reactor is a vertical cylindrical apparatus, in the central part of which there is a plasma-chemical zone (1). In this zone, using the plasmatron (2), the plasma-chemical transformation of the gaseous working fluid of the plasmatron (GTP) is introduced into the plasmatron through the fitting (3).

The gaseous working fluid of the plasmatron can be:

1) carbon dioxide during carbon dioxide reforming of methane (URM);

2) water vapor during methane steam reforming (PFP);

3) oxygen during the partial oxidation of methane (POM);

4) a mixture of all these gases with the addition of inert components (for example, such as nitrogen, argon, etc.).

Through another fitting (4), coolant is introduced into the plasma torch. The plasmatron (2) can be moved in the plasma-chemical zone (1) using the device (5). The temperature in the plasma-chemical zone reaches 5000-7000 ° C. The plasma-chemical zone is limited by a heat-insulating annular partition (6) made of a refractory material (ceramic). At the top of the plasma-chemical zone is a reflective partition (7), which is also made of refractory material. The products of the transformation of a gaseous working fluid having a high temperature from the plasma-chemical zone (1) through the gap between the heat-insulating annular partition (6) and the reflective partition (7) enter the annular buffer zone (8), where they are mixed with the starting reagents and heated to a temperature 800-1200 ° C. The heating of the resulting reagent mixture also occurs due to its contact with the heat-insulating annular partition. The starting reagents are fed into the annular buffer zone (8) through the central gas duct (9). The device (5) provides for the possibility of introducing (not shown in the figure) into the plasma-chemical zone (1) at least part of the feed stream directed to the buffer zone (8) through the central gas duct (9). The introduction of part of the feed stream into the plasma-chemical zone (1) through the device (5) ensures effective mixing of the reagents with products from the plasma torch torch, provides a decrease in temperature in the plasma-chemical zone and the possibility of its regulation, protects the heat-insulating annular partition (6) from direct exposure to plasma and hot gases torch plasmatron.

The reagent mixture obtained in the annular buffer zone (8) at a temperature of 800-1200 ° C passes through a fixed annular catalyst layer (10). The direction of movement of the reagent mixture in the annular catalyst layer is from the catalyst particles located closer to the center of the ring to the catalyst particles located on the periphery of the ring. The volumetric rate of transmission of reagents through a fixed ring catalyst layer (10) is 5000-15000 h ^-1 and largely depends on the need to achieve the required temperature in the ring buffer zone (8). From the fixed annular layer of catalyst, the reaction products enter the product gas duct (11), the annular shape of which passes to the top of the reactor into a pipe form. The reactor has a jacket (13) into which it is supplied through the nozzle (14), and the coolant is discharged through the nozzle (15). The catalyst is discharged through an annular cover (16).

The loading of the catalyst is as follows. Disassemble the flange connections along line (B), disassemble the flange connection along line (C), disassemble the flange connection along line (D), remove the ring cover of the catalyst layer (17). For fastening, the reactor has supports (18). The following examples illustrate this method.

Embodiments of the Inventions

Example 1. The process of carbon dioxide reforming of methane is carried out in the reactor described above. As the gaseous working fluid of the plasmatron, carbon dioxide is used. The process is carried out at a temperature of 900 ° C, a pressure of 1 bar and a space velocity of 10,000 h ^-1 . The catalyst used is Ni / Al ₂ O ₃ . The composition of the reaction mixture (% vol.): Methane - 20; carbon dioxide - 20; argon - 60. Upon completion of the process, the yield of H ₂ is 47%, the yield of CO is 51%, and the methane conversion is 98%.

Example 2. The process of steam reforming of methane is carried out in the reactor described above. As a gaseous working fluid of the plasmatron, a mixture of water vapor and carbon dioxide is used. The process is carried out at a temperature of 1000 ° C, a pressure of 7 bar and a space velocity of 1000 h ^-1 . The catalyst used is Ni / Al ₂ O ₃ . The composition of the reaction mixture (% vol.): Methane - 30; carbon dioxide - 60; argon - 10. Upon completion of the process, the yield of H ₂ is 60%, the yield of CO is 25%, the methane conversion is 95%.

Example 3. The process of partial oxidation of methane is carried out in the reactor described above. A mixture of carbon dioxide and oxygen is used as the gaseous working fluid of the plasmatron. The process is carried out at a temperature of 1000 ° C, a pressure of 7 bar and a space velocity of 1000 h ^-1 . The catalyst used is Ni / Al ₂ O ₃ . The composition of the reaction mixture (% vol.): Methane - 40; carbon dioxide - 30; argon - 30. Upon completion of the process, the yield of H ₂ is 95%, the yield of CO is 93%, and the methane conversion is 96%.

As can be seen from the above examples, the process according to the proposed method in the reactor described above can increase the methane conversion, the yield of H ₂ and CO. This can significantly improve the performance of the process. In addition to increasing the productivity of the process, the method can significantly reduce heat loss due to the location of the heat source (plasmatron) in the center of the reactor (in contrast to the peripheral location of the heat source in the prototype). The increase in process productivity is associated, inter alia, with the organization of the passage of the reaction mixture in the catalyst layer: the direction of movement from the center to the periphery leads to an increase in volume (pressure reduction) in the elementary catalyst layer, which contributes to the process flowing towards the reaction product - synthesis gas. An increase in the process productivity is also achieved due to the involvement in the reaction zone of the products of the plasma-chemical transformation of the working gas of the plasmatron, which initiate the process towards the formation of the main reaction products.

Example 4. The resulting synthesis gas is used to produce diesel fuel by the Fischer-Tropsch method. The large-scale calculations carried out for the process of carbon dioxide reforming of methane, taking into account the subsequent conversion of synthesis gas to diesel fuel, give the following main results:

1) the electric power of the plasmatron, kW 600.00 2) consumed electricity, MW · h / year 5382,00 3) operating costs, thousand rubles / year 4949.70 (including the cost of electric energy and CO ₂ ) 4) the cost of natural gas, thousand rubles / year 6728.40 5) the thermal power of the plasma torch, M cal / h 576.30 6) heat capacity of natural gas, kcal / kg / deg 0.94 7) heat capacity of CO ₂ , kcal / kg / deg 0.27 8) temperature in the reactor, ° C 1,200.00 9) CO ₂ consumption per 1 kg of natural gas, kg 2.75 10) the flow of CO ₂ through the plasmatron, kg / h 955.60 11) natural gas flow, kg / h 267.90 12) CO ₂ flow, kg / h 687.70 13) synthesis gas flow, kg / h 1004.60 14) residual CO flow, kg / h 502.30 15) calorie content of residual CO, kcal / h 1213363.50 16) the amount of diesel fuel received, tons / year 1452.10 17) revenue from sales of diesel fuel, thousand rubles / year 19893,10 18) net profit, thousand rubles / year 8215,00

Example 5. The resulting synthesis gas is used to produce diesel fuel by the Fischer-Tropsch method. The large-scale calculations carried out for the process of carbon dioxide reforming of methane, taking into account the subsequent conversion of synthesis gas to diesel fuel, give the following main results:

1) the electric power of the plasmatron, kW 600,0 2) consumed electricity, MW · h / year 5256.0

3) synthesis gas flow, kg / h 886 4) average temperature in the reactor, ° C 1200 5) CO ₂ flow through the plasmatron, kg / h 100.00 kmol / h 2.27 nm ³ / h 50.91 6) the flow of a mixture of natural gas and CO ₂ , kg / h 783.03 7) natural gas consumption, kg / h 236.27 8) natural gas consumption, nm ³ / h 330.78 9) natural gas consumption, nm ³ / year 2897662 10) consumption of CO ₂ , kg / h 549.75 11) synthesis gas flow, kg / h 886.03 12) the ratio of CO: H ₂ = 1: 1 1: 1 13) residual CO flow, kg / h 443.01 14) calorie content of residual CO, kcal / h 1070146.36 15) calorie content of residual СО, MW 1.24 16) natural gas costs, thousand rubles / year 5795.32 17) the thermal power of the plasmatron, Mcal / h 516.25 18) heat capacity of natural gas, kcal / kg / ° C 0.94 19) heat capacity of CO ₂ , kcal / kg 0.27 20) CO ₂ consumption per 1 kg of natural gas, kg 2.75 21) the amount of diesel fuel received, kg / h 146.19 t / day 3,51 t / year 1,280.66 22) the price of diesel fuel, rubles / t 13,700.00 23) revenue from sales of diesel fuel, thousand rubles / year 17545.09 24) operating expenses, thousand rubles / year 4833.84

The results obtained in examples 4-5 illustrate the commercial prospects of the proposed method.

Claims (4)

1. A method of producing synthesis gas by catalytic conversion of methane by passing reactants through a fixed catalyst bed, characterized in that an annular catalyst layer is used as a fixed catalyst layer, in which the reactants are passed from the inner to the outer surface of the annular catalyst layer; a mixture of methane with gaseous reactants, additionally containing the products of plasma-chemical decomposition of gaseous reactants or mixtures thereof, the thermal regime of percent the jar is provided by mixing plasma chemical decomposition products with a mixture of methane with the gaseous reactants and at least part of the reactants fed directly into plazmohimicheskim zone. 2. The method of producing synthesis gas according to claim 1, characterized in that carbon dioxide or water vapor or oxygen is used as gaseous reactants. 3. A reactor for producing synthesis gas by catalytic conversion of methane, comprising a fixed catalyst bed and a heating device for reactants and a catalyst, characterized in that the catalyst layer is made in the form of a ring in which the movement of the reactants is carried out from the inner to the outer surface of the annular catalyst layer, device heating of the reagents and the catalyst is made in the form of a plasmatron consuming working gas and located in the central part of the reactor in the plasma-chemical zone having a refractory insulation, between the plasmachemical zone and the catalyst bed there is a buffer zone in which the reagents and products of plasmachemical decay of the plasmatron working gas are mixed. 4. The reactor according to claim 3, characterized in that the plasmatron is arranged to move in the plasma chemical zone.