Process of producing liquid oxygenates via conversion of natural gas and installation to implement the same

FIELD: industrial organic synthesis and chemical engineering .

SUBSTANCE: invention relates to a process of producing liquid oxygenates, including methanol, C2-C4-alcohols, formaldehyde, lower organic acids, or mixtures thereof, and to installation for implementation the process. Process comprises successively supplying natural gas from complex gas preparation plant to a series of "gas-gas" heat exchangers and into annular space of at least one tubular reaction zone of reactor, wherein natural gas is heated to temperature of the beginning of reaction, whereupon heated gas is passed to the entry of the tubular reaction zone mixer, into which compressed air or oxygen is also injected to provide gas-phase oxidation in reaction zone of reactor. Resulting reaction mixture is discharged from reactor into a series of "gas-liquid" and "gas-gas" heat exchangers, wherein reaction mixture is cooled to ambient temperature and sent to separator, wherefrom liquid phase is passed through lower carboxylic acid recovery vessel to the system of rectification columns to isolate the rest of mixture components, whereas leaving gas is recycled to complex gas preparation plant. More specifically, oxidation is carried out within temperature range 240 to 450°C and pressure from 2 to 10 MPa at residence time of reaction mixture in reactor 2-6 sec and oxidant concentration 2 to 15 wt %. In reactor having mixers hollow and at least one tubular reaction zones, required temperature is maintained constant throughout all length of tubular reaction zone and at entries for compressed air or oxygen in mixers of each of tubular reaction zones and hollow reaction zone. Liquid oxygenate production plant is composed of aforesaid complex gas preparation plant, a series of "gas-gas" heat exchanger to heat natural gas, reactor, a series of "gas-liquid" and "gas-gas" heat exchangers to cool reaction mixture obtained in reactor, gas-liquid separator, lower carboxylic acid recovery vessel, and system of rectification columns to isolate the rest of products.

EFFECT: enabled implementation of the process directly near gas and gas condensate deposits, increased conversion of methane per one passage through reactor, and increased yield of oxygenates due to improved design of plant.

6 cl, 1 dwg, 1 tbl

 

The invention relates to a method of manufacturing a liquid oxygenates (oxygen-containing organic compounds), including methanol, With2-C4-alcohols, formaldehyde, lower organic acids or mixtures thereof, direct the homogeneous oxidation of natural gas, and installation for its implementation.

The depletion of world oil reserves forces us to reconsider the role of gas chemistry in the modern industry, the raw material which may be natural gas reserves are large enough. The main reasons for the limited use of natural gas as a raw material for the chemical industry are: high resistance to oxidation of the primary component of natural gas - methane greater than the resistance to oxidation products of incomplete oxidation; inaccessibility gas fields; the high cost of transportation of gaseous hydrocarbons to the consumer compared with the cost of transportation of liquid products. Major gas field in our country are located in remote areas of the Far North. The development of small energy (fuel and energy complexes) is constrained by lack of transport schemes for the delivery of reagents and inhibitors. Delivery to remote fields of methanol - base of hydrate inhibitor is a huge satr is you, several times the cost of its purchase.

Creating a compact apparatus for the production of methanol by means of direct conversion of natural gas directly to the fields in the structure of the complex gas treatment plants (GPP) would solve part of these problems for the gas industry. Considering the fact that a further increase in gas production will occur at the expense of deposits located in the Far North, this process takes priority.

The number of known methods for producing methane from natural gas. The main industrial method for the production of methanol is the catalytic processing of synthesis gas (mixture of CO and H2), which, in turn, receive a steam methane reforming using a catalyst. (Karavaev M.M., Leonov V.E. and others. Technology of synthetic methanol. M.: Chemistry, 1984, p.72-125). When this process has very high demands on the purity of natural gas, the high cost of energy for the production of synthesis gas and its clean, sophisticated and expensive equipment, a large number of intermediate stages. All this leads to the fact that methanol production small and medium capacities up to 2000 tons/day, become unprofitable.

Currently, the greatest interest is direct, bypassing the stage floor is placed synthesis gas, gas-phase oxidation of methane to methanol at high pressures. The process is carried out at pressures up to 10 MPa and temperatures of 400-450°in 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., O.V. Krylov Oxidative conversion of methane, M: Nauka, 1998, s-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 pre-heated to 200-500°With hydrocarbon gas under pressure from 2.5 to 15 MPa and an oxygen-containing gas in the mixing chamber, the subsequent 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, And, 2049086). However, the need for the use of the catalyst or additional reagents and strong heating of the reacting gases leads to 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 carbohydrate-containing gas in the reactor under a pressure of 1-10 MPa for 2-1000 seconds at a temperature of 300-500°in 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 unreacted methane, in the mixture with a source of hydrocarbon gas in the first reactor or the second reactor serially 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 370-450°C, a pressure of 5-20 MPa and a contact time of their Messiah. the reactor of 0.2-0.22 seconds, with cooling of the reaction mixture warmed up to 330 to 340°With introduction into the reactor of methanol (SU, A1, 1469788) or by cooling the reaction mixture without intermediate condensation and separation of up to 380-400°With 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 feeding successively compressed and heated hydrocarbon gas and compressed oxygen-containing gas into the mixing zone of consecutive reactors, followed by gas-phase oxidation of a hydrocarbon gas at initial temperature up to 500°C, 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 70-150°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 is not less than 0,vremeni 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. A considerable part of the supplied oxygen is consumed for oxidation of CO in the CO2, leading to additional reduction in the degree of conversion of the 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 of the inert m the 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 source of oxygen-containing gas with a compressor, sequential mixing and reaction zones with the supply pipe hydrocarbon gas in the 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 posleduyushim the allocation of methanol and piping for the exhaust gases in hydrocarbon source gas, and a pipeline for supplying the waste liquid oxygenated products in the first mixing zone of the reactor (EN, A, 2162460).

The disadvantage of this method is that all reaction zones of the reactor is made in the form of a hollow tube, which leads to a strong heating of the reaction mixture due to the heat released during the reaction and, as a consequence, the decrease of the yield of the target product. It is necessary to reduce the initial concentration of oxygen in the mixture, which also leads to a decrease in the degree of methane conversion and reduction of yield of methanol. The problem of low conversion of methane and low yield of the target product, the authors of the invention solve at the expense of increasing the number of reactors. As a consequence, there arises the need for additional equipment for cooling and separation of the reaction mixture at the outlet of the reactor for each of the parallel branches of the reactors, resulting in a significant expansion of the size and complexity of the last service. All this together significantly increases capital investment in the construction installation and ongoing costs of maintenance.

The present invention is directed to: 1 - improve the installation of the production of oxygenates (including methanol, formaldehyde, and other) by direct homogeneous oxidation nature of the aqueous gas, to increase the degree of methane conversion in a single pass through the reactor and, consequently, an increase in the yield of target products synthesis; 2 - simplification of the production of oxygenates due to the possibility of using directly in terms of gas and gas condensate fields in the installation of complex gas preparation.

The problem is solved by a method of producing oxygenates, including a consistent supply of natural gas with the installation of complex gas treatment plant (GTP) in a series of heat exchangers "gas-gas" and annulus, at least one tubular reaction zone of the reactor, where the heat flow of natural gas to the temperature of the beginning of the reaction, with subsequent supply heated gas to the input of the mixer tubular reactor into which is also fed with compressed air or oxygen, followed by gas-phase oxidation in the reaction zone of the reactor, with the conclusion obtained reaction mixture from the reactor in a series of heat exchangers gas-liquid and gas-gas, where it is cooled to ambient temperature, followed by feeding to the separator where the liquid phase, through the capacity to highlight the lower carboxylic acid is fed into the system rectification column for separation of the remaining components of the mixture, and the exhaust gas is returned to unit. When this oxidation spending is in the reactor, with mixers, hollow and at least one tubular reaction zone, while maintaining a constant temperature throughout the length of the tubular reaction zone of the reactor and by compressed air or oxygen into the mixer of each tubular reaction zone and a hollow reaction zone.

The oxidation is carried out in the temperature range 250-450°C, pressure of 2-10 MPa, at a concentration of oxidant 2-15 wt.%. The time of the reaction mixture in each reaction zone may vary from 2 to 6 seconds, respectively shifts the equilibrium towards the formation of some or other products of synthesis.

The invention also relates to a device for producing oxygenates containing a source of natural gas treatment plant (GTP), a series of heat exchangers "gas-gas" for natural gas heating, the reactor containing the mixer and the reaction zone including a cavity and at least one tubular reaction zone, the number of heat exchangers gas-liquid and gas-gas for cooling the obtained reaction mixture, the separator, which separates liquid from gas tank for the selection of lower carboxylic acids, and a number of distillation columns for separation of the remaining products.

The method also allows to change the amount of methanol and formaldehyde. So when oxidation at temperatures which 400-450° C and a pressure of 8-10 MPa mostly get methanol. During oxidation at a temperature of 450°C, a pressure of 2-5 MPa mostly get the methanol content of formaldehyde to 25 wt.%.

The reactor (figure 1), consists of consecutive faucets natural gas and oxidant and reaction zones and equipped with devices to enter the reaction mixture and the supply of oxidant. The number of the reaction zones of the reactor depends on the impurity content2-C4hydrocarbons in the feed gas and the size of the construction area. The design of the reactor provides for up to three entry points oxidant, which allows the oxidation process under the conditions optimal for dominance in the reaction products of one or another connection. The reaction zone of the reactor is made on the principle of heat exchanger "gas-gas", and the last reaction zone is made in the form of a hollow tube, for maximum utilization of the heat released during the reaction, heat exchanger "gas-liquid"is located directly at the outlet of the reaction mixture from the reactor).

The design of the reactor allows the use of hydrocarbon raw materials, enriched With2-C4hydrocarbons (up to 15 wt.%), which are oxidized in the first place, and depending on conditions gives the corresponding alcohols and aldehyde or oxygenates with less Chi is scrap carbon in the chain. Maintenance of the set temperature of the process is performed by applying annulus of the reaction zone of the reactor, the source of hydrocarbons previously, passing a series of heat exchangers is heated to the temperature required to initiate the reaction. The oxidizer is fed into the mixer reactor cold, allowing the reaction mixture enters the reaction zone with a temperature optimum for the start of the reaction.

The inner walls of the reactor system can be lined with inert in this process the material. Each chamber of the reactor is equipped with a set of thermocouples for temperature control process. The temperature control process can be done in two ways - it is the variation of the concentration of an oxidant or varying the flow of refrigerant in the tube space of the reaction zones.

The design of the reactor system also allows you to use gas without additional purification from impurities other hydrocarbons, it is easy to vary the concentration of the oxidant supplied to the reaction in a wide range, the temperature of the process is controlled along the entire length of the reaction zone and does not exceed the threshold, beyond which begins the destruction of the target products. In addition, the design of the reactor allows to shift the oxidation process in the direction of those or other products is tov.

The invention allows to apply the method directly in terms of gas and gas condensate fields for the production of methanol used as a hydrate formation inhibitor

Flexible variation of the basic process parameters, operating temperature, pressure, initial concentration of oxidant and time - shifts the oxidation process towards formation of the required product. So in the oxidation of hydrocarbons containing up to 15% With2-C4hydrocarbons, variation of parameters allows you to change in liquid products the concentration of methanol in the framework of 25-45%, formaldehyde 1-25%, ethyl alcohol 0-15%, organic acids is 0.5-1.5%.

The oxidation process occurs in the isothermal mode, allowing you to significantly improve technical and economic performance of the process.

The original design of the reactor and the feed of oxidant at several points along the length of the reactor site allows you to increase the quantity of oxidizing agent and, accordingly, the conversion of hydrocarbons and the output of products of oxidation.

Exhaust gases back into the process of installation of complex gas as performance PPC a lot more performance installation for producing oxygenates, the increase in nitrogen content in tons of the commodity gas will be not more than 0.3%, which corresponds OST 51.40-93. When placing the unit to gas power plants, the return gas practically does not lose its nutritional value.

This installation is characterized by clean production, where there are no harmful emissions.

Further, the invention is illustrated by examples of its implementation and the accompanying drawings in which are shown:

- figure 1 - scheme of the reactor;

- figure 2 - flow chart of installation.

Installation (figure 2) to obtain oxygenates direct homogeneous oxidation of natural gas contains a gas treatment plant, the reactor 1 for oxidation of natural gas (figure 1), consisting of 2 mixers, reaction zones 3 and 4, made in the form of a heat exchanger and a hollow tube, respectively, the input device is heated natural gas 5 and oxidant 6. The length of the reactor are thermowells 7 for temperature control of the process.

The installation also contains serially arranged heat exchangers "gas-liquid" 8 and "gas-gas" 9 and 10, the separator 11, the pumps 12, 13, 15, 17, distillation columns 14, 16 and container 18, for separation of carboxylic acids. Installation can be equipped with additional distillation column for separation of C2-C4of spirits.

Natural gas compressor 12 is supplied with the unit into the shell side of the heat exchanger 10, where it heats the I to a temperature of 150° With and then fed into the annulus of the heat exchanger 9, where it is heated to a temperature of 300°and then goes into the tube space of the tubular reactor 1, where it is heated to a temperature of 450°and enters the mixer tubular reactor. The air (oxygen), pre-compressed by the compressor 13 to the required pressure, is fed to the mixers of the reaction zones of the reactor 1. After stirring the reaction mixture enters into the tubular reaction zone of the reactor where the oxidation occurs at a constant temperature. Next, the reaction mixture temperature to 450°comes With second mixing chamber of the reactor, mixed with air and fed into the second hollow reaction zone. At the exit of the reactor, the reaction mixture enters the tube of the heat exchanger 8 where it is cooled to a temperature of 450-470°C. Next, the reaction mixture passes sequentially through the tube space of the heat exchangers 9 and 10, cooling down to ambient temperature, and fed into the separator 11, where the separation of the gas and liquid phases. The gas phase is sent back to the unit, the liquid phase, passing through the tank 18 containing reagents for separation of carboxylic acids, the pump 17 is fed into the distillation column 16, where it is separated methanol, raw, and CC the rest of the column 16 naso is om 15 is fed to distillation column 14 for selection of formalin and 2-C4-alcohols.

The table lists examples that illustrate the basic performance of the proposed method.

The placeholderExample No. 1Example # 2Example # 3
The number of reactors, PC1111
The number of stages of oxidation in each reactor2233
The composition of natural gas, %CH4- 72
about.CH4- 98CH4- 98CH4- 98With2H6- 14
N2- 1N2- 1N2- 1With3+- 12,5
CO2- 1CO2- 1CO2- 1N2- 1
CO2- 0,5
The hydrocarbon gas stream through the reactor, m3/h7330700070007000
The conversion of gas, % 11,31012,516,8
Consumption of natural gas, m3/h2107008751176
Complete consumption of oxygen (air), m3/h1010 (Air)2666,7 (Air)84010000 (Air)
The oxygen concentration at the inlet into the mixing zone of the reactor, % vol.1,54410
The pressure in the reactor, MPa10882,5
The temperature of the mixture at the inlet of the reactor, °430450450400
The yield of methanol, kg/h180500625535,5
The total yield of organic products, kg/h1966057571309,5
The release of formaldehyde, kg/h7596491,2
Exit C2-C4alcohols, kg/h--192,2
The yield of carboxylic acids, kg/h303690,6
The volume of thedamage gas, m3/h83409387651015194

1. The method of producing a liquid oxygenates, including methanol, formaldehyde,2-C4alcohols, lower carboxylic acids or mixtures thereof, comprising the sequential supply of natural gas with the installation of complex gas treatment plant (GTP) in a series of heat exchangers "gas-gas" and annulus, at least one tubular reaction zone of the reactor, where the heat flow of natural gas to the temperature of the beginning of the reaction, with subsequent supply heated gas to the input of the mixer tubular reaction zone of the reactor, into which is also fed with compressed air or oxygen, followed by gas-phase oxidation in the reaction zone of the reactor output the resulting reaction mixture from the reactor in a series of heat exchangers gas-liquid and "gas-gas", where it is cooled to ambient temperature, followed by feeding to the separator where the liquid phase through the capacity to highlight the lower carboxylic acid is fed into the system rectification column for separation of the remaining components of the mixture, and the exhaust gas is returned to unit, while the oxidation is carried out in the temperature range 250-450°C, pressure of 2-10 MPa, residence time of the reaction mixture in the reactor 2-6 and concentration of oxidant 2-15 wt.% react is re, with mixers, hollow and at least one tubular reaction zone, while maintaining a constant temperature throughout the length of the tubular reaction zone of the reactor and by compressed air or oxygen into the mixer of each tubular reaction zone and a hollow reaction zone.

2. The method according to claim 1, characterized in that the oxidation at a temperature of 400-450°C, a pressure of 8-10 MPa mostly get methanol.

3. The method according to claim 1, characterized in that the oxidation at a temperature of 450°C, a pressure of 2-5 MPa mostly get the methanol content of formaldehyde to 25 wt.%.

4. The method according to claim 1, characterized in that use natural gas containing C2-C4 hydrocarbons to 15 wt.%.

5. The method according to any one of claims 1 and 4, characterized in that use raw natural gas.

6. Device for producing liquid oxygenates, including methanol, formaldehyde,2-C4-alcohols and lower carboxylic acid, or a mixture thereof according to claim 1, consisting of the installation of complex gas, which is the source of natural gas, a sequential series of heat exchangers "gas-gas" for natural gas heating, the reactor containing mixers and reaction zone containing a cavity and at least one tubular reaction zone, the number of heat exchangers "gas-liquid" and "gas-gas" for the cooling gap the value obtained reaction mixture, the separator, which separates liquid from gas tank for the selection of lower carboxylic acids and the number of distillation columns for separation of other products.



 

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The invention relates to the chemical industry, in particular to methods of regeneration of silver catalysts for the preparation of formaldehyde from methanol

The invention relates to the technology of organic synthesis, and in particular to an improved process for the preparation of formalin used in chemical industry, medicine and agriculture

The invention relates to an improved method of dewatering solution of formaldehyde containing formaldehyde, water and methanol, including the distillation of the specified solution of formaldehyde in the presence of exciting water connection with obtaining the formaldehyde-containing product that contains significantly less water than the original solution, and use a solution of formaldehyde containing methanol at a molar ratio of methanol to formaldehyde 0.3 to 1.5:1, obtaining the formaldehyde-containing product in the form of a complex with methanol

The invention relates to an improved method for the removal of formaldehyde or its adducts of organic liquid mixtures obtained in the production of methyl methacrylate containing at least a carboxylic acid or an ester of carboxylic acid and formaldehyde or its adducts, which forms a two-phase mixture of water, comprising at least one extraction liquid organic mixture in the system liquid-liquid using water as the extractant with getting the flow of the organic phase and flow of the aqueous phase, and the flow of the organic phase contains significantly reduced the concentration of formaldehyde or its adducts compared with the liquid organic mixture

The invention relates to a method of obtaining from semiformal Monomeric formaldehyde high purity, used as a monomer in the production of high molecular polyacetylenic resins, as well as in the synthesis of numerous organic compounds based on it
The invention relates to the field of chemical technology and can be used in the manufacture of formaldehyde in the chemical, petrochemical and other industries
The invention relates to the field of chemical technology and can be used in the manufacture of formaldehyde in the chemical, petrochemical, etc

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to production of butyl alcohols via oxo synthesis, which comprises propylene hydroformylation stage using cobalt carbonyls as catalyst; distilling off butyric aldehyde concentrate containing, in addition to butyric aldehydes, butyl alcohols, water, unsaturated and saturated dibutyl ethers, butyl formates, butyl butyrates, hydrocarbons, aldehydes and alcohols C-8, C12-acetals, and other high-boiling by-products; and liquid-phase hydrogenation of above concentrate on alumino-zinc-chromium catalyst at 280-320°C and pressure 240-300 kg/cm2 followed by recovering commercial isobutyl and n-butyl alcohols from resulting hydrogenate by rectification of six columns. The latter stage comprises: isolation of unreacted butyric aldehydes, methanol, water, and hydrocarbon traces from top part of first column; passing bottom product of the first column into second column and isolation of butyl alcohols with traces of unsaturated and saturated dibutyl ethers from top part of second column; passing bottom product of the second column into third column and isolation of residual butyl alcohols from top part of third column operated at residual pressure 40-400 mm Hg; passing second-column distillate into fourth column and isolation of crude isobutyl alcohol from top part of forth column and crude butyl alcohol from bottom part of the same column. Commercial isobutyl alcohol is obtained on fifth column and commercial butyl alcohol on sixth column. Furthermore, hydrogenation raw mix is supplemented by mixture of water and third-column distillate fraction 140-170°C at weight ratio (0.3-4.0):1, respectively, so that summary concentration of water in hydrogenation raw mix is maintained between 2.0 and 6.0 wt %.

EFFECT: increased yield of butyl alcohols.

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