RU2533731C2 - Synthetic gas production method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is referred to the area of petroleum chemistry and may be used for synthesis of methanol, dimethyl ether, hydrocarbons according to Fischer-Tropsch method. Methane-containing raw material is subjected to oxidative conversion at temperature of 650-1100°C in the riser. Miscrospheric or shredded catalyst based on metal oxides capable of multiple reduction-oxidative transfers is used as the oxidizer. Regenerated catalyst is recovered by its oxidation in the regenerator and addition to the riser in the bottom-up flow of methane-containing raw material; the riser operates in a through flow mode and duration of the raw material stay in the reaction area is 0.1-10 s. The regenerated catalyst exiting from the riser is separated from the product of synthetic gas and delivered to the regenerator. Catalyst regeneration is performed in fluidized, forced fluidized or semi-through flow by oxidation with oxygen-containing agent. The produced synthetic gas has H₂/CO ratio within the range of 7.5-2.5.

EFFECT: improvement of the product area efficiency, potential usage of hydrocarbon raw material containing carbon dioxide at reduced explosion and fire hazard and at low energy consumption.

5 cl, 3 tbl, 13 ex

Description

The invention relates to the field of petrochemistry and more specifically to a method for producing synthesis gas, a mixture of hydrogen and carbon monoxide, which is known as feedstock, for example, for the synthesis of methanol, dimethyl ether, hydrocarbons by the Fischer-Tropsch method.

A known method of producing synthesis gas by the partial oxidation of methane with oxygen. The reaction is carried out at a temperature of 800-900 ° C. The resulting synthesis gas consists of hydrogen and carbon monoxide with a molar ratio of H ₂ / CO close to 2 (Arutyunov VS, Krylov OV Oxidative transformations of methane. M: Nauka, 1998).

The disadvantage of this method is the high cost of producing oxygen, as well as the explosiveness of the process due to the formation of mixtures of methane with oxygen.

A known method of producing synthesis gas, described in patent US 2665199 A, publ. 01/05/1954, class C01B 3/30, C01B 3/44, according to which synthesis gas is obtained from gaseous hydrocarbons in the presence of solid particles of metal oxide in a fluidized state in a plant consisting of a reactor and a regenerator. In the reactor, the oxidation of hydrocarbons by oxygen contained in the solid particles proceeds; in the regenerator, the oxidation of solid particles occurs. The hydrocarbon oxidation reaction is carried out in a fluidized bed having the following disadvantages:

- uneven residence time of the raw materials in the reaction zone, as a result, some of the raw materials are subjected to excessive conversion to the formation of soot, and the other part does not achieve complete conversion;

- the average fictitious residence time of the raw material in the reaction zone is not small enough to provide the highest selectivity of the process.

Closest to the technical nature of the proposed is the method of producing synthesis gas described in patent US 6833013 B1, publ. 12/21/2004, class C01B 3/32, according to which synthesis gas is obtained by the partial oxidation of light hydrocarbons with oxygen contained in solid particles containing metal oxide and undergoing redox cycles. Light hydrocarbons are oxidized in the reactor at a temperature of 800-1100 ° C and a pressure of 0.5-5 MPa, solid particles are oxidized in the regenerator at a temperature of 750-1050 ° C.

This makes it possible to prevent the possibility of explosion and ignition due to the absence of gaseous oxidizing agents in the reaction zone and to use the thermal energy of the catalyst coming from the regenerator in which the exothermic oxidation reaction of the metal components of the catalyst takes place for the endothermic reaction of the partial oxidation of methane, which reduces energy costs and ultimately the cost process. The resulting synthesis gas contains 60.2% H2 and 30.6% CO, i.e., the H ₂ / CO ratio in it is 1.97, which is well suited for industrial needs.

However, the disadvantage of the described method is the carrying out of the hydrocarbon oxidation reaction and the regeneration of solid particles in the fluidized bed, which results in a very low specific removal of the product, namely 335 liters of synthesis gas per kilogram of catalyst per hour, which negatively affects the performance of the reactor. Specific removal refers to the amount of product obtained by carrying out the process on a catalyst of a certain mass per unit time [Melnikov E.Ya. Reference book of nitrogen. / M.: Chemistry, 1967, 492 p.]. The specific removal of the product in the closest analogue was calculated based on the amount of catalyst in the reactor - 1400 g and the product yield - 516 l / h.

High process pressure leads to an increase in capital costs and significantly increases the requirements for the level of safety.

In the regenerator, a by-product is obtained - a gas containing 95.4 mol%. nitrogen and 4.6 mol%. oxygen. Nitrogen of such purity does not meet the requirements for technical nitrogen, and is released into the atmosphere. Its use without additional purification is impossible.

The objective of the invention is to increase the specific removal of the product while maintaining the advantages of the closest analogue - eliminating the formation of explosive mixtures and low energy consumption with the possibility of producing synthesis gas with a ratio of H ₂ / CO in the range of 1.5-2.5. Another result of the invention is to increase the purity of the obtained nitrogen to ensure its use as technical nitrogen without further purification. In addition, when implementing this method, it is possible to use raw materials containing carbon dioxide as methane-containing gas.

The solution of this problem is achieved by the fact that the proposed method for producing synthesis gas, including the oxidative conversion of methane-containing raw materials at a temperature of more than 650 ° C in a reactor using a microspherical or crushed catalyst based on metal oxides capable of multiple redox transitions as an oxidizing agent, and regeneration of the regenerated by its oxidation in the regenerator, from which the regenerated catalyst enters the reactor, and carrying out the oxidative conversion in the elevator reactor, through which the catalyst continuously passes from the bottom up in the methane-containing feed stream during operation of the reactor in the through flow mode and the residence time of the feed in the reaction zone for 0.1-10 s, then the reduced catalyst coming out of the reactor is separated from the synthesis gas product - and sent to the regenerator.

The oxidative conversion is preferably carried out at a temperature of 650-1100 ° C, most preferably 850 ° C.

The regeneration of the catalyst is preferably carried out in a fluidized or forced fluidized or semi-through stream by oxidation with an oxygen-containing agent.

Preferably, oxygen or air is used as the oxygen-containing agent.

It is generally accepted that the fluidized bed is present at gas flow rates of up to 0.8 m / s. At gas speeds of 0.8-1.5 m / s, the system is characterized by the state of a forced fluidized bed. Systems in which the movement of solid particles is carried out at gas velocities reaching 1.5-3.0 m / s are called semi-through flow. Gas flow rates above 3-4 m / s correspond to the movement of solid particles in the gas stream in the through flow mode [S. Hadzhiev Cracking of oil fractions on zeolite-containing catalysts. / M .: Chemistry, 1982. - 280 p.].

Reactors operating in the last two modes are called flow-through (elevator reactors).

The process is continuous, and it is carried out in two spatially separated apparatuses: a reactor and a regenerator. In such a reactor-regenerator system, the catalyst, as it breaks down, is removed from the system in the form of dust and replaced with fresh. By adjusting the residence time of the feedstock in the reaction zone within 0.1-10 s, a through flow mode is maintained, preventing the transition to a half through flow mode.

The resulting synthesis gas and the recovered catalyst are removed from the reactor and the spent (recovered) catalyst stream is separated from the target product stream. The stream of the reduced catalyst through the transport line is fed to the regeneration unit, where the catalyst is oxidized in the fluidized bed, which is supported by the flow of an oxygen-containing agent (air, oxygen). Then the catalyst is separated from the regeneration gases and transport lines, again served in the conversion reactor, as described above.

Regeneration gases are technical nitrogen that can be used without further purification. It meets the requirements of GOST 9293-74 “Gaseous and liquid nitrogen”, according to which technical nitrogen contains from 99.0% vol. nitrogen and up to 1.0% vol. oxygen.

The process is continuous and consists of the following stages:

- the conversion of hydrocarbons into synthesis gas (with the restoration of the catalyst to a metallic state);

- catalyst regeneration (with oxidation of its metal components).

The stages of oxidation and reduction of the catalyst are parallel and continuous.

Thus, the catalyst is continuously circulated and oxygen is transferred from the regeneration zone to the reaction zone, and the material and thermal balances are reduced.

The technical result achieved is:

- to increase the specific removal of the product;

- the possibility of using hydrocarbon raw materials containing a significant amount of carbon dioxide - up to 30%;

- to reduce the risk of explosion and fire, low energy consumption, the production of synthesis gas with a ratio of H ₂ / CO in the range of 1.5-2.5;

- the possibility of obtaining a by-product of industrial nitrogen (the nitrogen content of which is at least 99.0% vol.).

The following examples illustrate and explain the proposed technical solution, but in no way limit it.

Example 1

Methane is fed to the bottom of the elevator reactor, which is in contact with the microspherical catalyst coming from the regenerator. The catalyst consists of nickel and cobalt oxides supported on alumina. The catalyst, caught in an upward flow of methane, moves upward through the reactor, and methane is oxidized by the oxygen contained in the catalyst into carbon monoxide and hydrogen by the reaction

CH ₄ + [O] → CO + 2H ₂

Methane is supplied at such a rate as to maintain a residence time of the feed in the riser reactor of 2.1 s. The temperature in the reaction zone is kept at 850 ° C. The product pairs are separated from the catalyst, and the catalyst is sent to a regenerator. In the regenerator, the catalyst is oxidized with air. The temperature in the regeneration zone is kept at 600 ° C. The oxidized catalyst from the regenerator is again sent to the lower part of the reactor.

Raw material conversion - the ratio of the amount of converted raw materials to the original, expressed in%

X is the conversion of raw materials, wt.%

m _f - mass of raw materials, kg

m _p - mass of hydrocarbons in products, kg

Specific synthesis gas removal - the amount of synthesis gas obtained from one kilogram of catalyst per hour

P - specific removal of synthesis gas, l / (kg cat. · H)

V _sg is the volume of synthesis gas obtained during time τ, l

m _cat is the mass of the catalyst in the reactor, kg

τ - time, s

The molar ratio of H ₂ / CO is the ratio of the amount of hydrogen to the amount of carbon monoxide in the reaction products

The process indicators are shown in table 1.

As can be seen from the table, the specific removal of synthesis gas increases significantly with a high value of the conversion of raw materials and the simultaneous production of technical nitrogen with a purity of 99.1% vol.

Example 2

The experiment is carried out as in example 1, but the process is carried out in the presence of a catalyst containing iron oxide deposited on alumina at a temperature in the reaction zone of 750 ° C.

The conversion of raw materials according to the example is 60.3%.

The specific removal of synthesis gas according to the example is 4600 l / (kg cat. · H).

The process indicators are shown in table 1.

Example 3

The experiment is carried out as in example 1, but the temperature in the reaction zone is maintained equal to 950 ° C.

The conversion of raw materials according to the example is 99.4%.

The specific removal of synthesis gas according to the example is 7700 l / (kg cat. · H).

The process indicators are shown in table 1.

Example 4

The experiment is carried out as in example 1, but the temperature in the reaction zone is maintained equal to 1000 ° C.

The conversion of raw materials according to the example is 99.6%.

The specific removal of synthesis gas according to the example is 7700 l / (kg cat. · H).

The process indicators are shown in table 1.

Example 5

The experiment is carried out as in example 1, but the process is carried out in the presence of a catalyst containing cobalt oxide deposited on alumina at a temperature in the regeneration zone of 800 ° C.

The conversion of raw materials according to the example is 95.1%.

The specific removal of synthesis gas according to the example is 7300 l / (kg cat. · H).

The process indicators are shown in table 1.

Example 6

The experiment is carried out as in example 5, but the process is carried out at a temperature in the regeneration zone of 1100 ° C.

The conversion of raw materials according to the example is 95.1%.

The specific removal of synthesis gas according to the example is 7300 l / (kg cat. · H).

The process indicators are shown in table 1.

Example 7

The experiment is carried out as in example 1, but the process is carried out in the presence of a catalyst containing nickel oxide deposited on alumina, with a residence time of the feed in the reaction zone of 0.1 s and a temperature in the reactor of 1100 ° C.

The conversion of raw materials according to the example is 20.4%.

The specific removal of synthesis gas according to the example is 40,400 l / (kg cat. · H).

The process indicators are shown in table 1.

Example 8

The experiment is carried out as in example 7 with a residence time of the raw material in the reaction zone of 5.0 s and a temperature in the reactor of 850 ° C.

The conversion of raw materials according to the example is 99.4%.

The specific removal of synthesis gas according to the example is 2900 l / (kg cat. · H).

The process indicators are shown in table 1.

Example 9

The experiment is carried out as in example 8, with a residence time of the raw material in the reaction zone of 10.0 s.

The conversion of raw materials according to the example is 99.2%.

The specific removal of synthesis gas according to the example is 1500 l / (kg cat. · H).

The process indicators are shown in table 1.

Example 10

The experiment is carried out as in example 1, but as a methane-containing raw material, a gas mixture consisting of methane and ethane with a concentration of the latter of 20 vol% is fed to the elevator reactor, and the catalyst contains manganese oxide supported on alumina.

The conversion of raw materials according to the example is 92.3%.

The specific removal of synthesis gas according to the example is 8000 l / (kg cat. · H).

The process indicators are shown in table 1.

Example 11

The experiment is carried out as in example 1, but as a methane-containing gas in the elevator reactor serves a gas mixture consisting of methane and carbon dioxide with a concentration of the latter of 10 vol.%, And the catalyst contains copper oxide supported on alumina.

The conversion of raw materials according to the example is 91.6%.

The specific removal of synthesis gas according to the example is 7250 l / (kg cat. · H).

The process indicators are shown in table 1.

Example 12

The experiment is carried out as in example 11, but as a methane-containing gas in the elevator reactor serves a gas mixture consisting of methane and carbon dioxide with a concentration of the latter of 30 vol.%.

Example 13

The experiment is carried out as in example 1, but as a methane-containing gas, a gas mixture is supplied to the reactor, the composition of which is given in table 2. The composition of this mixture corresponds to the average composition of associated petroleum gases (APG) of Russia and the CIS. Associated gases - gaseous hydrocarbons accompanying crude oil, under reservoir pressure conditions, dissolved in oil and released during its production. Associated gases contain 30-80% methane, 10-26% ethane, 7-22% propane, 4-7% butane and isobutane, 1-3% n-pentane and higher n-alkanes. Also, these gases contain hydrogen sulfide, carbon dioxide, nitrogen, inert gases, mercaptans. The average gas factor of Russian oil fields is 95-112 cubic meters. m / t (the amount of associated gases per cubic meter per 1 ton of extracted oil). To calculate the average composition of the model mixture (concentrations of methane, ethane, propane and butane), we used data on the composition of associated petroleum gases of some oil fields in the Russian Federation and the CIS (table 3) [Lapidus A.L., Golubeva I.A., Zhagfarov F.G. Gas chemistry. M .: TsentrLitNefteGaz, 2008].

The concentration of each component in the model, the mixture was calculated

c _cpi = 100 · Σ (c _ij · p _j ) / Σ (Σ (c _ij · p _j ) _i ),

where c _ij is the concentration of the i-th component in the j-th field

p _j - 7th field

The catalyst consists of nickel and cobalt oxides supported on alumina.

The conversion of raw materials according to the example is 97.6%.

The specific removal of synthesis gas according to the example is 10,000 l / (kg cat. · H).

The process indicators are shown in table 1.

The molar ratio of H ₂ / CO in the resulting synthesis gas is 2.1.

The nitrogen concentration in the regeneration gas is 99.1 vol.

As can be seen from table 1, a decrease in the residence time of the raw material in the reaction zone below a certain value (2 s) leads to an increase in product removal, but a decrease in the degree of conversion, which in turn will require separation of unreacted raw materials from the reaction products. An increase in the residence time of the feedstock in the reaction zone over 10 s is associated with a decrease in the flow rate, which can lead to the transition of the reactor from a through flow mode to a half flow mode and, accordingly, a decrease in product removal.

When the reaction temperature is reduced to 750 ° C, the degree of conversion and removal of the product, as well as the purity of the resulting nitrogen, decrease.

Thus, the proposed method for producing synthesis gas, which allows under optimal conditions at high values of the conversion of methane-containing raw materials to increase the specific removal of synthesis gas by 20-30 times compared with the prototype when the ratio of H ₂ / CO in the range of 1.5-2.5 eliminating the danger of explosion and fire and low energy consumption and at the same time get a by-product - nitrogen of technical purity.

Table 1 Conditions and Results No. pr. Raw materials Catalyst Temperature in the reactor, ° C Temperature in the regenerator, ° C The residence time of the raw materials in the reaction zone, s Specific removable synthesis gas, l / (kg cat. · H) The conversion of raw materials, mass. H ₂ / CO, mol / mol The concentration of N2 in the regeneration products,% vol. one CH ₄ NiO + Co ₃ O ₄ + Al ₂ O ₃ 850 600 2.1 7300 95.1 2.1 99.1 2 CH ₄ Fe ₃ O ₄ + Al ₂ O ₃ 750 600 2,3 4600 60.3 2.2 99.0 3 CH ₄ NiO + Co ₃ O ₄ + Al ₂ O ₃ 950 600 1.9 7700 99,4 2.2 99.3 four CH ₄ NiO + Co ₃ O ₄ + Al ₂ O ₃ 1000 600 1.8 7700 99.6 2.2 99.1 5 CH ₄ Co ₃ O ₄ + Al ₂ O ₃ 850 800 2.1 7300 95.1 2.1 99.1 6 CH ₄ Co ₃ O ₄ + Al ₂ O ₃ 850 1100 2.1 7300 95.1 2.1 99,2 7 CH ₄ NiO + Al ₂ O ₃ 1100 600 0.1 40,400 20,4 2.2 99.1 8 CH ₄ NiO + Al ₂ O ₃ 850 600 5,0 2900 99,4 2.2 99,2 9 CH ₄ NiO + Al ₂ O ₃ 850 600 10.0 1500 99,2 2.2 99.3 10 CH ₄ + 20% C ₂ H ₆ MnО2 + Al ₂ O ₃ 850 600 2.1 8000 92.3 1.8 99.0 eleven CH ₄ + 10% CO ₂ CuO + Al ₂ O ₃ 850 600 2.1 7250 91.6 1.8 99.0 12 CH ₄ + 30% CO ₂ CuO + Al ₂ O ₃ 850 600 2.2 6215 91.6 1.4 99.0 13 PNG * NiO + Co ₃ O ₄ + Al ₂ O ₃ 850 600 2.1 10,000 97.6 1.7 99.1 * The composition of this mixture corresponds to the average composition of associated petroleum gases (APG), presented in table.2.

table 2 The average composition of associated petroleum gases (APG) Gas component CH ₄ C ₂ H ₆ C ₃ H ₈ C ₄ H ₁₀ Concentration, vol.% 70 12 12 6

Table 3 Composition of oil associated gases of some oil fields in Russia and the CIS Field Oil reserves, million tons Component,% vol. CH ₄ C ₂ H ₆ C ₃ H ₈ C ₄ H ₁₀ Samotlor, Zap. Siberia 3200 82.88 4.23 6.48 3,54 Varyogansk 66 77.25 6.95 9.42 4.25 Pravdinskoe 1800 58.40 11.65 14.53 9.20 South Balyk 200 68.16 9.43 15.98 4,50 Romashkinskoye, Tatarstan 2700 43.41 20.38 16.23 6.39 Kuleshovskoe, Samarsk. reg. 60 39.91 23.32 17.72 5.78 Korobkovskoye, Volga. reg. 90 76.25 8.13 8.96 3,54 Yarinskoye Perm. 80 23.90 24.90 23.10 13.90 Kamennolozhskiy Perm. 80 28.90 25.90 20.30 9.30 Gnedintsevskoe, Ukraine 38 5.50 27.39 38.35 12.82 Uzen, Kazakhstan 1100 83.53 8.73 3.98 1.92 Zhetybai, Kazakhstan 330 78.06 8.49 6.32 3.46 Rechitskoe, Belarus 114 51.60 15.74 16.11 9.15

Claims (5)

1. A method of producing synthesis gas, including the oxidative conversion of methane-containing raw materials at a temperature of more than 650 ° C in a reactor using a microspherical or crushed catalyst based on metal oxides capable of multiple redox transitions as an oxidizing agent, and regenerating the reduced catalyst by oxidizing it in the regenerator from which the regenerated catalyst enters the reactor, characterized in that the oxidative conversion is carried out in an elevator reactor through which the th catalyst continuously passes from bottom to top in the flow of methane-containing feedstock, when the reactor is in through flow mode and the residence time of the feedstock in the reaction zone is 0.1-10 s, then the reduced catalyst coming out of the reactor is separated from the product — synthesis gas — and sent to the regenerator . 2. The method according to claim 1, characterized in that the oxidative conversion is carried out at a temperature of 650-1100 ° C. 3. The method according to claim 2, characterized in that the oxidative conversion is carried out at a temperature of 850 ° C. 4. The method according to one of claims 1 to 3, characterized in that the regeneration of the catalyst is carried out in a fluidized or forced fluidized or semi-through stream by oxidation with an oxygen-containing agent. 5. The method according to claim 4, characterized in that oxygen or air is used as the oxygen-containing agent.