Processing of natural gas with methanol obtaining

 

(57) Abstract:

The invention relates to the field of chemical technology and can be used for chemical and petrochemical plants producing synthetic alcohols, in particular methanol. The essence of the method is that the method of production of methanol comprises steam-oxygen conversion of natural gas, waste heat of the synthesis gas, the partial removal of carbon dioxide, drying, compression to a pressure of 8.5 - 9.0 MPa and the synthesis of methanol at low temperature catalyst in two stages - preliminary flow and the main circulation, at this preliminary stage of the synthesis are before drying and compression under pressure stage steam-oxygen conversion, followed by a main step of the synthesis. Dehydration synthesis gas is carried out by separation of the water-methanol fraction. Preliminary synthesis carried out on a copper-containing catalyst at a volumetric rate 2000 - 6500 h-1. The method allows for energy-saving technology. 2 C.p. f-crystals.

The invention relates to the field of chemical technology and can be used for chemical and petrochemical plants producing synthetic is with the heating process natural gas to 380 - 400oC fire in the heater, cleaned from sulphur, mixed with water vapor, steam reforming in a tubular furnace, steam-oxygen conversion in the shaft of the Converter, the cleaning gas from the carbon dioxide, kompremirovannyj synthesis gas, the synthesis of methanol in a deck columns on copper-containing catalyst circulation method (inventor's certificate SU N 1465410, 01 3/32, 1989).

The disadvantage of this method is the high energy intensity of the process.

A known method of producing methanol from synthesis gas, comprising two stages of the synthesis of methanol at elevated temperature and pressure, where the first stage of the synthesis are in the flow reactor, and the second stage in the reactor recycle, and the volume ratio of CO/(H2+ CO2the output from the second stage reactor adjust by adding to the gas supplied to the second stage, additional gas stream containing an excess of hydrogen or carbon oxides.

The disadvantage of this method are significant energy consumption and low efficiency of use of reactive components in the reaction mixture due to the high solubility of carbon dioxide in methanol with condensation after the first stage of the synthesis.

Known methods for the teaching of converted gas waste heat of the product gas partial removal of carbon dioxide from the converted gas mixture to obtain the factorial of f, defined as (H2- CO2)/(CO2+ CO), 2.05-2.1, drying the remaining moisture by freezing and engagement Almagell, compression of dry gas to a pressure of 8.5 - 9.0 MPa and the synthesis of methanol in a deck columns with stepped vipasyana gas in the copper-zinc-chromium catalyst at a temperature of 230-250oC circulation method (Analog, RF patent N 2099320, published. 1997).

The disadvantages of this method are the increased energy consumption due to the need for compression only fresh synthesis gas to a pressure of synthesis and a significant flow of cold on the condensation of the residual moisture of the fresh synthesis gas at the stage of compression and at the stage of compression.

The claimed invention aims to remedy these disadvantages and providing a cost-effective method of producing methanol, comprising a steam-oxygen conversion of natural gas to synthesis gas, the utilization of its heat, partial removal from synthesis gas, carbon dioxide, drying, compression to a pressure of 8.5-9.0 MPa and the synthesis of methanol at low temperature catalyst, and with the circulation and, the dehydration and compression is carried out between the mentioned stages.

Dehydration synthesis gas before compression is performed with the separation of the water-methanol fraction.

In addition, a preliminary synthesis carried out on a copper-containing catalyst at a volumetric rate 2000-6500 h-1.

The method is performed by the following examples.

Example 1. Natural gas under pressure 1.6 MPa in the number 8380 nm3/h undergo the process of steam-oxygen conversion of obtaining 51200 nm3/hour wet the converted gas, after disposing of its heat and the separation of moisture from synthesis gas at a temperature of 40oC partially remove carbon dioxide, while receiving 25725 nm3/h of synthesis gas of the following composition,%: CO 15.89, CO211.55, H269.16, H2O 0.43, CH41.48, Ar 0.62, N20.87, with the factorial of 2.1. The resulting synthesis gas is separated into two streams, most of which, passing through the regenerative heat exchanger, heated to 233oC heat of the reaction mixture after stage precatalyzed synthesis and flows into the flow reactor loaded in two layers of low-temperature copper-containing catalyst for synthesis of methanol in a volume of 8 m3. In the first layer being mixed with the second, a smaller stream of the reaction mixture so that the temperature at the inlet to the second layer dropped to 226oC. At the outlet of the second catalyst layer, the temperature of the reaction mixture increased to 257oC and has the following composition,%: CO 14.728, CO211.764, H267.596, H2O 0.718, CH3HE 2.099. The volumetric rate of synthesis of methanol in the reactor precatalyzed is 3200 h-1. The reaction mixture is cooled to 5oC when you do this, it is water-methanol mixture in an amount of 709 kg/h with 90% methanol and drying gas, and further 24000 nm3/h of dry synthesis gas is compressed by the compressor synthesis gas to a pressure of 9.0 MPa, and divide into 4 equal flow by the number of paths of synthesis, and then mixed with the gas stream after the circulation compressor and served on the second stage of the synthesis, in the column shelf type by volume of catalyst 3.8 m3. On the methanol synthesis catalyst, placed on five shelves, is the synthesis of methanol so that after a column of synthesis gas has the following composition,%: CO 2.24, CO24.43, H257.15, H2ABOUT 1.62, CH3HE 4.03. The temperature at the outlet of the last shelf is 263oC. After cooling in the internal heat exchanger, the reaction mixture pic the mixture. The resulting methanol-raw contains 20.05% water column productivity synthesis, the crude methanol is 2.816 t/h After separation of the water-methanol mixture circulating gas is divided into two streams, most of which goes to the suction side of the circulation compressor, and a smaller stream in the form of purge gases derived from the synthesis loop. The total production capacity of the plant crude methanol 11.97 t/h with a concentration of methanol 80,53%.

Example 2. Natural gas under pressure 1.6 MPa in the number 8272 nm3/h undergo the process of steam-oxygen conversion of obtaining 50557 nm3/hour wet the converted gas, after disposing of its heat and the separation of moisture from synthesis gas at a temperature of 40oC partially remove carbon dioxide, while receiving 25403 nm3/h of synthesis gas of the following composition,%: WITH 15.89, CO211.55, H269.16, H2ABOUT 0.43, CH41.48, Ar 0.62, N20.87, factorial, equal to 2.1. The resulting synthesis gas is separated into two streams, most of which, passing through the regenerative heat exchanger, heated to 248oC heat of the reaction mixture after stage precatalyzed synthesis and flows into the flow reactor loaded in two layers of low-temperature copper is electroplated by raising the temperature to 275oC. the Reaction mixture after the first layer is mixed with a second, smaller flow of the reaction mixture so that the temperature at the inlet to the second layer dropped to 238oC. At the outlet of the second catalyst layer, the temperature of the reaction mixture increased to 262oC and has the following composition,%: WITH 15.081, CO211.616, H267.829, H2O 0.759, CH3HE 1.647. The volumetric rate of synthesis of methanol in the reactor precatalyzed is 6350 h-1. The reaction mixture is cooled to 5oC when you do this, it is water-methanol mixture in an amount of 556 kg/h with 86.88% methanol content and is drying gas, and further 24000 nm3/h of dry synthesis gas is compressed by the compressor synthesis gas to a pressure of 9.0 MPa, and divide into 4 equal flow by the number of paths of synthesis, and then mixed with the gas stream after the circulation compressor and served on the second stage of the synthesis, in the column shelf type by volume of catalyst 3.8 m3. On the methanol synthesis catalyst, placed on five shelves, is the synthesis of methanol so that after a column of synthesis gas has the following composition,%: CO 2.248, CO24.42, H256.99, H2ABOUT 1.59, CH3HE 4.05. The temperature at the outlet of the last shelf is 263.7oC is a bill circulating water with simultaneous condensation of water-methanol mixture. The resulting methanol-raw contains 19.73% water column productivity synthesis, the crude methanol is 2.817 t/h After separation of the water-methanol mixture circulating gas is divided into two streams, most of which goes to the suction side of the circulation compressor, and a smaller stream in the form of purge gases derived from the synthesis loop. The total production capacity of the plant crude methanol 11.82 t/h with a concentration of methanol 80,57%.

Example 3. Natural gas under pressure 1.6 MPa in the number 8448 nm3/h undergo the process of steam-oxygen conversion of obtaining 51632 nm3/h wet the converted gas, after disposing of its heat and the separation of moisture from synthesis gas at a temperature of 40oC partially remove carbon dioxide, while receiving 25943 nm3/h of synthesis gas of the following composition,%: WITH 15.89, CO211.55, H269.16, H2ABOUT 0.43, CH41.48, Ar 0.62, N20.87, with the factorial of 2.1. The resulting synthesis gas is separated into two streams, most of which, passing through the regenerative heat exchanger, is heated to a temperature of 224oC heat of the reaction mixture after stage precatalyzed synthesis and flows into the flow reactor loaded in two layers of low-temperature mediterraneum a temperature of up to 266oC. the Reaction mixture after the first layer is mixed with a second, smaller flow of the reaction mixture so that the temperature at the inlet to the second layer dropped to 219oC. At the outlet of the second catalyst layer, the temperature of the reaction mixture increased to 254oC and has the following composition,%: CO 14.514, CO211.852, H267.442, H2O 0.699, CH3HE 2.382. The volumetric rate of synthesis of methanol in the reactor precatalyzed is 2162 h-1. The reaction mixture is cooled to 5oC when you do this, it is water-methanol mixture in an amount of 808 kg/hour with 91.31% methanol content and is drying gas, and further 24000 nm3/h of dry synthesis gas is compressed by the compressor synthesis gas to a pressure of 9.0 MPa, and divide into 4 equal flow by the number of paths of synthesis, and then mixed with the gas stream after the circulation compressor and served on the second stage of the synthesis, in the column shelf type by volume of catalyst 3.8 m3. On the methanol synthesis catalyst, placed on five shelves, is the synthesis of methanol so that after a column of synthesis gas has the following composition,%: CO 2.248, CO24.42, H256.99, H2ABOUT 1.59, CH3HE 4.05. The temperature at the outlet of the last shelf is 262.8odue to the circulating water with the simultaneous condensation of water-methanol mixture. The resulting methanol-raw contains 20.25% water column productivity synthesis, the crude methanol is 2.815 t/h After separation of the water-methanol mixture circulating gas is divided into two streams, most of which goes to the suction side of the circulation compressor, and a smaller stream in the form of purge gases derived from the synthesis loop. The total production capacity of the plant crude methanol 12.068 t/h with a concentration of methanol 80,53%. As can be seen from the examples, the proposed method of production of methanol compared to the prototype 0.9-1.2% reduced energy consumption for compression of the synthesis gas to a pressure of synthesis. In addition, increases the efficiency of the use of reactive components in the reaction mixture in methanol with condensation after the first stage of the synthesis and improves the quality of crude methanol.

1. The method of processing natural gas to methanol obtaining, including steam-oxygen conversion of natural gas to synthesis gas, the utilization of its heat, partial removal from synthesis gas, carbon dioxide, drying, compression to a pressure of 8.5 and 9.0 MPa and the synthesis of methanol at low temperature catalyst, characterized in that the synthesis is carried out in two stages - preliminary pray carried out between these stages.

2. The method according to p. 1, characterized in that the dehydration synthesis gas is carried out by separation of the water-methanol fraction.

3. The method according to p. 1, characterized in that the preliminary synthesis carried out on a copper-containing catalyst at a volumetric rate 2000 - 6500 h-1.

 

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