A method of producing methanol and installation for its implementation

 

The invention relates to a method for production of methanol and installation for its implementation. The method comprises feeding to a reaction zone heated hydrocarbon gas and compressed air, gas-phase oxidation of a hydrocarbon gas at elevated temperature and pressure, cooling the reaction mixture in the reactor, the final cooling of the reaction mixture before separation, in which the cooled reaction mixture is separated into exhaust gases and liquid products, rectification obtained during separation of liquid products with the release of methanol and the flue gas. When this process is carried out at constant temperature 430-470oC and a pressure of 8 MPa and the filing of the original hydrocarbon gas from a plant of complex gas preparation carried out sequentially in two streams: the first of which is heated to the reaction temperature and supplied directly to the inlet of the reaction zone, and the second is served after heating in the heat exchanger the gas-gas to a temperature that allows the cooling of the reaction mixture in two stages: cooling by mixing directly in the reaction zone with the second stream and cooling the tubular part of the reactor through the wall of the tube, and how exactly is get in the separation process and in the heat exchanger "gas-gas" cold source of hydrocarbon gas, while exhaust gases are returned to the installation of complex gas. A distinctive feature of the installation is that the source of the hydrocarbon gas is to install complex gas cooling zone is a tubular part of the reactor, the reaction zone and cooling zone provided with a device for inputting the initial hydrocarbon gas, heated in the heat exchanger the gas-gas to a temperature that allows the cooling of the reaction mixture in two stages: by mixing with a stream of hydrocarbon source gas, heated in the heat exchanger the gas-gas directly into the reaction zone in the tubular part of the reactor through the wall of the tube, and the device for final cooling of the reaction mixture before separation is made in the form of a heat exchanger installed in series "gas-liquid", connected to the reactor, a separator and a rectifying junction, and heat exchanger "gas-gas", connected to the reactor and installation of complex gas. The invention allows to apply the method directly in terms of gas and gas condensate fields. 2 S. and 4 C.p. f-crystals, 1 tab., 2 Il.

The invention relates to oblige gas (natural gas).

Natural gas is projected to be a major hydrocarbon resource for energy and chemical industry of the XXI century. The main deposits of gas and gas condensate are located in remote areas of the Far North, 87% of the production is in the North of the Tyumen region. The development of small energy (fuel and energy complexes) is constrained by lack of transport schemes for the delivery of reagents and inhibitors. The main inhibitor in the fight against hydroabrasive in gas production is methanol, the delivery of which to the remote fields represents a huge cost several times the price to buy methanol from petrochemical plants.

Creating a compact apparatus for the production of methanol by the method of converting natural gas directly from fields in the installations of complex gas treatment plants would solve the problems described above for the gas industry. Considering the fact that a further increase in gas production will be done at the expense of numerous small fields, located in the Far North, this process takes priority.

The number of known ways of converting methane to methanol. Wide is talities transformation in methanol (Karavaev M M, Leonov, C. E. and others. "Technology of synthetic methanol", Moscow, "Chemistry", 1984, S. 72-125). However, implementation of this process requires sophisticated equipment, high demands on the purity of the gas, and the high cost of energy for the production of synthesis gas and its treatment, a large number of intermediate stages of the process, the lack of profitability of small and medium enterprises with a capacity of less than 2000 tons/day.

Currently, the greatest interest is direct, bypassing the stage of synthesis gas production, gas-phase oxidation of methane to methanol at high pressures. The process is carried out at pressures up to 10 MPa and temperatures of 400-450oIn tubular reactors with a relatively low initial concentrations of oxygen, followed by cooling gas-liquid mixture and separation of liquid products, of which the rectification into methanol (Arutyunov B. C. Krylov, O. C. "Oxidative conversion of methane", Moscow, "Science", 1998, S. 130-145). However, the low degree of methane conversion per pass through the reactor does not exceed 3-5%, and, respectively, low yield of methanol, the cumbersome process hinder the practical implementation of the method for producing methanol by direct oxidation of methane.

A known method of producing methanol, comprising separate feeding preggo gas in the mixing chamber, the next stage partial oxidation of methane with oxygen concentrations of 1-4% vol. with the addition of reagents (metal oxide catalyst, the higher gaseous hydrocarbons or oxygen-containing compounds, cold oxidant in the reaction zone of the reactor, cooling the reaction mixture in the heat exchanger, separation of methanol from the liquid reaction products in the separator, the flow of exhaust gaseous reaction products at the reactor inlet (EN, A, 2049086). However, the need for the use of the catalyst or additional reagents and strong heating of the reacting gases lead to the reduction of the yield of methanol and increase the likelihood of sooting.

A method of producing methanol, comprising separate feeding into the mixer hydrocarbon gas (natural gas or methane) and oxygen-containing gas (air or oxygen), the subsequent filing of the mixture in an inert reactor, gas-phase partial oxidation of hydrocarbon gas in the reactor under a pressure of 1-10 MPa for 2-1000 seconds at a temperature of 300-500oIn the absence of catalyst, the oxygen content of 2-20 vol.%, the allocation of methanol in the condenser of the reaction products, the return exhaust the reaction gas containing the second reactor, sequentially connected to the first reactor (GB, 2196335, And). The method provides a high yield of methanol and 5-15% methane can react with each pass through the reactor, however, a high response time limits the performance of the reactor methanol.

A known method of producing methanol by separate feed and oxidation of hydrocarbon gas to oxygen-containing gas at 370-450oC, a pressure of 5-20 MPa and time contact them in the reactor of 0.2-0.22 seconds, cooling the reaction mixture warmed up to 330 to 340oWith the introduction into the reactor of methanol (SU, A1, 1469788) or by cooling the reaction mixture without intermediate condensation and separation of up to 380-400oWith interstage heat exchangers installed in the reactor, after which the reaction mixture flows on 2-3 consecutive stages of oxidation (SU, A1, 1336471). In the first case, the need for additional flow and re-allocation of methanol leads to its inevitable losses that otherwise require the installation of additional cooling circuits of circulation in additional cooling agent.

The closest technical solution is a method for the production of methanol (EN, A, 2162460), including separate supply p is a recreational zone of consecutive reactors, subsequent gas-phase oxidation of a hydrocarbon gas at initial temperature to 500oC, pressure up to 10 MPa and the oxygen content of not more than 8 vol.%, cooling the reaction mixture after each reaction zone of the reactor at 70-150oWith through the wall of the flow of cold hydrocarbon gas, quenching of the reaction mixture after the last reaction zone by lowering the temperature of the reaction mixture not less than 200oWith time, constituting less than 0.1 time of her stay in the reaction zone, cooling and separation of the cooled reaction gas mixture in the exhaust gas and liquid products after each successively positioned reactor, a distillation of liquid products with the release of methanol, the flow of exhaust gases in hydrocarbon source gas, or burning.

The known method does not provide the required heat removal rate of the reaction that leads to the necessity of reducing the degree of conversion of the hydrocarbon gas. In addition, even using as oxidant oxygen is not possible to effectively recycle hydrocarbon gas due to the rapid increase in the concentration of carbon oxides. While significant testconversion carbon source gas and further overheating of the reaction mixture. In addition, the additional amount of hydrocarbon source gas must be burned to provide steam stage distillation of liquid products.

Known plant for production of methanol containing successively installed and connected by pipelines mixing chamber connected to separate sources of hydrocarbon gas and air or oxygen, the reactor from an inert material with heating elements for partial oxidation of methane in the mixture fed to the reactor under pressure, a condenser and separator for the separation of methanol from the reaction products, the capacity for recycled gaseous reaction products by pipeline to serve them in the original hydrocarbon gas or mixing chamber. (GB, 2196335, AND). However, a high residence time of the reactants in the reactor does not provide high performance installation, which makes the process practically not applicable in an industrial environment.

Closest to the present invention is a device for producing methanol, which contains the hydrocarbon source gas, the compressor and the heater to compress and heat the gas, the oxygen-containing source gosection areas with pipelines hydrocarbon feed gas in a first mixing zone of the reactor and the oxygen-containing gas into each of the mixing zone, recuperative heat exchangers for cooling the reaction mixture through the wall of the flow of cold hydrocarbon gas, installed near the output ends of all of the reaction zones of the reactor pipelines for further supplying heated hydrocarbon gas in a heater, a cooler-condenser, a separator for separating the exhaust gases and liquid products followed by separation of the methanol and the piping for the exhaust gases in hydrocarbon source gas, and a pipe for supplying the waste liquid oxygenated products in the first mixing zone of the reactor (EN, A, 2162460).

The impossibility of rapid heat removal vysokomaslichnoy volume of the oxidation reaction of hydrocarbon gas leads to the need to reduce the amount of hydrocarbon gas and, consequently, the degree of conversion of the hydrocarbon gas. In addition, even when used as an oxidizer oxygen impossible effective recycling of hydrocarbon gas due to the rapid increase in the concentration of carbon oxides. A considerable part of the supplied oxygen is consumed for oxidation of CO and CO2leading to advanced the art. The installation also requires the burning of additional quantities of hydrocarbon source gas to provide steam stage distillation of liquid products. The necessity of cooling gas-liquid mixture after each reactor for the separation of liquid products and its subsequent heating before the next reactor leads to considerable complication of the technological scheme, the increase in units and additional power consumption.

The present invention aims at simplifying the production of methanol due to the possibility of using directly in terms of gas and gas condensate fields in complex with dehydration unit or with the installation of low-temperature separation of gas per one reaction zone with a minimum amount of equipment and returning the gaseous reaction products in the technology of gas on the installation of complex gas preparation, the quality of the gas must comply with the requirements of marketable gas.

The problem is solved by a method of producing methanol, comprising feeding into a reaction zone heated hydrocarbon gas and compressed air, gas-phase oxidation uglee cooling the reaction mixture before separation, in the process, the cooled reaction mixture is separated into exhaust gases and liquid products, rectification obtained during separation of liquid products with the release of methanol and the flue gas. The difference of the proposed method is that the process is conducted at a constant temperature 430-470oC (preferably 450oC) and a pressure of 8 MPa and the filing of the original hydrocarbon gas with the installation of complex gas treatment carried out sequentially in two streams: the first of which is heated to the reaction temperature and supplied directly to the inlet of the reaction zone, and the second is served after heating in the heat exchanger the gas-gas to a temperature that allows to carry out cooling of the reaction mixture in two stages: cooling by mixing directly in the reaction zone with the second stream and cooling the tubular part of the reactor through the wall of the tubes, and the final cooling of the reaction mixture is performed in the heat exchanger gas-liquid methanol-raw which is obtained in the separation process and in the heat exchanger "gas-gas" cold hydrocarbon source gas while the exhaust gases are returned to the installation of complex gas.

In the reaction zone useful the ke for the production of methanol, contains a source of hydrocarbon gas, a reactor for carrying out gas-phase oxidation of hydrocarbon gas consisting of the reaction zone and cooling zone, a device for final cooling of the reaction mixture before separation of the exhaust gases and liquid products of distillation node for the separation of methanol and other liquid products. The difference between the proposed facility from the well-known is the fact that the source of the hydrocarbon gas is to install complex gas. The cooling zone is a tubular part of the reactor, the reaction zone and cooling zone provided with a device for inputting the initial hydrocarbon gas, heated in the heat exchanger the gas-gas to a temperature that allows the cooling of the reaction mixture in two stages: cooling by mixing directly in the reaction zone with the second stream and cooling the tubular part of the reactor through the wall of the tube, and the device for final cooling of the reaction mixture before separation is made in the form of sequentially installed heat exchanger gas-liquid connected to the reactor, a separator and a rectifying junction, and heat exchanger gas-gas, connected the lined material inert to the reaction mixture.

The digester is equipped with thermowells and input devices to control and regulate the temperature in the reaction zone.

The required inlet temperature in the reactor is carried out by heating the hydrocarbon gas to the required temperature in the furnace.

The maximum yield of methanol is obtained by gas-phase oxidation of a hydrocarbon gas with a constant temperature in the isothermal mode in order to reduce the formation of CO, CO2N2and reduce air flow.

Maintaining a constant temperature in the reaction zone of the reactor by sequential input of hydrocarbon gas (cold gas) after heating it in the heat exchanger "gas-gas" to the appropriate temperature directly into the reaction zone by means of the input unit and valve controls the temperature in the reaction zone, are installed on the input lines of the gas.

Further cooling of the reaction mixture produced in the tubular part of the reactor, where the annulus as a cooling agent is supplied a source of hydrocarbon gas after heating it in the heat exchanger "gas-gas" to the appropriate temperate "gas-liquid" where heating of the crude methanol from the bottom of the separator to the desired temperature conducting rectification at the entrance to the distillation column.

Final cooling of the reaction mixture, typically to a temperature of t=20-30oWith occurs in the heat exchanger "gas-gas" using the source gas with the installation of complex gas. Next, the cooled gas enters the separator, which is allocated a dry gas and methanol raw. Methanol-raw through a heat exchanger with a temperature of 100-120oWith enters the distillation column. The temperature of the top of the column 72-75oWith the pressure in the column of 0.15-0.2 MPa.

Methanol with a concentration of up to 94% goes to the Park, and CC the rest of the column containing formalin, is directed at the implementation (recycling). Dry gas from the separator is returned to the installation of complex gas.

The holding stage of the oxidation process in virtually isothermal conditions is, according to theoretical and experimental studies, the optimal condition for the production of methanol. This greatly increases the degree of conversion of hydrocarbon gas per one reaction zone. This in turn increases the yield of methanol.

Note the giving process control reactions and its automation. This method completely eliminates the overheating of oxidation products in the reaction zone, thus eliminating the formation of areabrandy products in the oxidation products. In addition, the use of this method allows to carry out the reaction product raw with minimal energy costs.

This method of producing methanol with a high enough degree of accuracy to model mathematically with the aid of computer programs.

The application of this method of production of methanol is distinguished by the fact that in terms of gas and gas condensate fields allows to obtain methanol in one step with a high degree of methane conversion.

The advantage of this method is that the exhaust gases back into the process of installation, comprehensive training, without affecting the mode of its operation and quality of marketable gas, as the capacity of the plant for production of methanol is much less than the performance of complex gas, and the increase in the content of nitrogen compounds in the product gas will be not more than 0.3%, which meets the requirements of OST 51.40-93.

The reaction can be done in the adiabatic regime in the reactor Iceni volume of gas required to produce the same volume of methanol.

The task of the production of methanol at low conversion facilitates installation on gas installations, where the content of2+C3in the source gas reaches up to 7 vol.%, which in turn increases the yield of methanol.

This unit is the production of methanol is different in a way that is environmentally friendly production, where there are no harmful emissions.

Further, the invention is illustrated with specific examples of its implementation and the accompanying drawings, in which Fig.1 depicts a General view of the installation for the production of methanol; Fig.2 - scheme of the reactor.

Device for producing methanol includes a reactor 1 (Fig.1) for carrying out gas-phase oxidation of hydrocarbon gas. The reactor 1 consists of two zones 2 and 3, one of which, zone 2, is reactionary and provided with a device 4 for input of cold hydrocarbon gas after heating in the heat exchanger "gas-gas" to the appropriate temperature. Zone 3 consists of a tubular part for cooling the reaction mixture through the wall of the tube 5 mounted in the tube plate 6 on the inlet and outlet of the reaction see the temperature in the reaction zone.

The installation also includes a device for final cooling of the reaction mixture before separation, which is performed in the form of a heat exchanger installed in series "gas-liquid" 9 and heat exchanger "gas-gas" 10 connected to the reactor 1. The heat exchanger "gas-liquid" 9 communicated with the rectifying junction, for example a distillation column 11 and the separator 12. The heat exchanger "gas-gas" 10 communicated with the installation of 13 comprehensive training. Distillation column 11 is connected to the apparatus 14 air cooling, which is communicated with a reflux tank 15 connected to a pump 16. The reactor 1 is connected to the compressor 17 for supplying compressed air and oven 18 heated hydrocarbon gas.

Hydrocarbon natural gas (methane content up to 98%) with the installation of drying gas through the heat exchanger "gas-gas" 10 (Fig.1) with a temperature of 10-20oWith, where is the final cooling of the reaction mixture before the separator 12, enters the tubular part 3 of the reactor 1. In the reactor 1 of the original hydrocarbon gas is heated to a temperature of 300-350oSince, then through a heater 18 with temperature 430-470oWith fed into the reaction zone 2 of the reactor 1, which has consistently served the compressed air pressure P=8.0 MP is the soup of the serial input of the source mixture after the heat exchanger the gas-gas 10 through the input unit. Next, the reaction mixture through the tubular part 3 of the reactor 1 at a temperature of up to 250oWith enters the heat exchanger "gas-liquid" 9 to heat the crude methanol from the separator 12.

Cooled to a temperature of 80-140oWith the reaction mixture enters the heat exchanger "gas-gas" 10, where the final cooling to a temperature of 20-30oWith, and fed into the separator 12.

In the separator 12 separates into dry gas and methanol raw, then dry gas is returned to the installation of 13, and methanol raw through the heat exchanger "gas-liquid" 9 with a temperature of 100-120oWith enters the distillation column 11. From distillation column 11 methanol vapor through the device 14 air cooling comes in the reflux tank 15. Part of the methanol from the reflux tank 15 is supplied to the irrigation of the column 11, and the carrying amount of methanol by means of a pump 16 is directed in the Park methanol.

Example, confirming the ability of the proposed method for the production of methanol.

Cold dry natural gas (methanol content 98%) from the unit 13 with a flow rate of 20,000 kg/h with pressure P=8.0 MPa through the heat exchanger "gas-gas" 10, where it is heated to 100oWith, is directed into the tubular part 3 of the reactor 1 to the op>oC and fed to reaction zone 2 of the reactor 1, which successively is supplied compressed air from the compressor 17 in the amount of 6000 kg/h.

In reaction zone 2 is constantly maintained temperature within 450oWith due to the serial input of part of the hydrocarbon gas after heating in the heat exchanger "gas-gas" to the appropriate temperature by means of the valve, temperature controller installed on the input of cold gas. The reaction time is 1-1 .5 C.

Then the reaction mixture is fed to the tubular part 3 of the reactor for cooling and temperatures up to 250oWith forwarded to the heat exchanger "gas-liquid" 9 to heat the crude methanol from the bottom of the separator 12.

Dry gas from the separator in the amount of 25000 kg/h returns to the installation of 13, and methanol raw number of 860 kg/h is directed to the distillation column 11. Methanol vapor through the device 14 are received in the reflux tank 15, where the pump 16 is directed in the Park methanol, the other part is supplied to the upper part of the column 11 to maintain the temperature within the 75oC.

Claims

1. A method of producing methanol, comprising feeding into a reaction zone heated hydrocarbon g the discussion of the reaction mixture in the reactor, final cooling of the reaction mixture before separation, in which the cooled reaction mixture is separated into exhaust gases and liquid products, rectification obtained during separation of liquid products with the release of methanol and the flue gas, wherein the process is conducted at constant temperature 430-470oC and a pressure of 8 MPa and the filing of the original hydrocarbon gas from a plant of complex gas preparation carried out sequentially in two streams: the first of which is heated to the reaction temperature and supplied directly to the inlet of the reaction zone, and the second is served after heating in the heat exchanger the gas-gas to a temperature that allows the cooling of the reaction mixture in two stages: cooling by mixing directly in the reaction zone with the second stream and cooling the tubular part of the reactor through the wall of the tubes, and the final cooling of the reaction mixture is performed in the heat exchanger gas-liquid methanol-raw which is obtained in the separation process and in the heat exchanger "gas-gas" cold hydrocarbon source gas while the exhaust gases are returned to the installation of complex gas.

2. The method according to p. 1, OE maintain the concentration of oxygen in the range from 1 to 2.5%.

4. Installation for the production of methanol containing hydrocarbon source gas, a reactor for carrying out gas-phase oxidation of hydrocarbon gas consisting of the reaction zone and cooling zone, a device for final cooling of the reaction mixture before separation of the exhaust gases and liquid products of distillation node for the separation of methanol and other liquid products, characterized in that the source of the hydrocarbon gas is to install complex gas cooling zone is a tubular part of the reactor, the reaction zone and cooling zone provided with a device for inputting the initial hydrocarbon gas, heated in the heat exchanger the gas-gas to a temperature allow cooling of the reaction mixture in two stages: by mixing with a stream of hydrocarbon source gas, heated in the heat exchanger "gas-gas", directly in the reaction zone and in the tubular part of the reactor through the wall of the tube, and the device for final cooling of the reaction mixture before separation is made in the form of a heat exchanger installed in series "gas-liquid", connected to the reactor, separator and rectification Osinovka on p. 4, characterized in that the reactor is equipped with thermowells and input devices to control and regulate the temperature in the reaction zone.

6. Installation according to p. 4, characterized in that the inner wall of the reaction zone lined with a material inert to the reaction mixture.

 

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