RU2539656C1 - Method for producing liquid hydrocarbons of hydrocarbon gas and plant for implementing it - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil and gas chemistry, in particular to a method of oil-associated and hydrocarbon gas processing. A method for producing liquid hydrocarbons of hydrocarbon gas is accompanied by water production; if necessary, it involves desulphurisation, flue gas heating of a heat-energised instrumentation assembly followed by synthetic gas production by high-temperature reforming by conversion with atmospheric oxygen, to prepare liquid hydrocarbons and water followed by water distillation from residual hydrocarbons. The method is characterised by the fact that before high-temperature reforming, the hydrocarbon gas and air are subject to low-temperature pre-reforming; a reaction gas mix flow supplied from a pre-reforming reactor is separated into two flows; one of the flows is introduced into a pre-reforming converted gas feed line into the reforming reactor; before injection, the second flow is supplied into the reforming reactor for carbon dioxide venting; the gas flows are then combined; liquid hydrocarbons are produced of the synthetic gas using a narrow-fraction catalyst system; the pre-reforming, reforming and liquid hydrocarbon synthesis reactors use the radial filtration of reaction flows; additionally, water is produced of flue gas and pre-reforming gas outflows; water process loss is compensated with water from a collector, wherein the water recovered from the flue gasses, pre-reforming gasses, synthetic liquid hydrocarbons, optionally reforming gasses, flows. What is also declared is a plant for implementing the method.

EFFECT: creating the method and a light plant producing liquid hydrocarbons to be used on remote, low-pressure deposits, for flared gas processing; the method and plant are characterised by a closed internal water supply system enabling avoiding water discharge into the environment that generally leads to economical efficiency of the method and plant.

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Description

The invention relates to oil and gas chemistry, in particular to methods for processing associated petroleum gas and hydrocarbon gas of an unstable composition.

Background of the invention and prior art.

Currently, there is a problem of processing associated petroleum gas, as well as gas from fields with an unstable composition. Such gases are either flared or there is a need to lay pipelines to existing gas pipelines or to the nearest gas processing plant. Gas from low-pressure wells lies at great depths and is difficult to transport due to low pressure. Therefore, the utilization of associated petroleum gas, gas with an unstable composition and low-pressure gas (for the purpose of producing liquid hydrocarbons) is of great importance for solving one of the main environmental problems - reducing the emission of carbon dioxide into the atmosphere directly at the field, in order to satisfy the own demand of oil and gas producers for motor fuel, as well as for obtaining a commercially liquid product without expensive gas transportation.

Known methods for converting natural gas to liquid hydrocarbons include two stages. First, a catalytic conversion of natural gas is carried out to produce a synthesis gas consisting of H ₂ and CO, as well as some CO ₂ . In the second stage, liquid hydrocarbons consisting of higher C ₅₊ hydrocarbons are obtained from synthesis gas as a result of catalytic synthesis. This process may also include an additional stage of stabilization (refinement) of liquid hydrocarbons to obtain the final products.

From patent RU 2247701 С07С 1/04, published on March 10, 2005, a method is known for converting natural gas to higher hydrocarbons. The method includes the catalytic conversion of natural gas by reacting with water vapor and an oxygen-containing gas to produce synthesis gas in two stages. At the first stage in the pre-reforming reactor at a temperature of (430-500) ° C, the hydrocarbons C ₂ and higher contained in the feed gas are converted to methane, CO and CO ₂ , after which at the second stage the gas mixture is heated to a temperature of (550-650) ° C and together with oxygen or an oxygen-containing gas (air) is sent to an autothermal reforming reactor, where under pressure (3-4) MPa is converted to synthesis gas. The temperature of the synthesis gas at the outlet of the reforming reactor is maintained at (950-1050) ° C. The resulting synthesis gas is cooled, and then sent to a liquid hydrocarbon synthesis reactor, where at a pressure of (2-4) MPa and a temperature of (180-240) ° C, a crude synthesis product is obtained consisting of lower hydrocarbons, higher hydrocarbons, water and residual synthesis gas. Then carry out the separation of the liquid and gaseous phases. Part of the exhaust gases with the addition of natural gas is subjected to steam reforming in a separate apparatus, after which they are introduced into the main synthesis gas stream in front of the liquid hydrocarbon synthesis reactor and / or into the gas stream in front of the reforming reactor. Pre-hydrocarbon gas passes through the sulfur removal unit. Using this method allows to increase the yield of liquid fuel and reduce the emission of CO ₂ .

The installation for implementing this method comprises a natural gas desulfurization unit, an evaporator for adding water vapor to the desulfurized gas, a heat exchanger for heating the gas mixture with water vapor, a pre-reforming reactor, a heat exchanger for additionally heating the pre-reforming exhaust gases, an autothermal reforming reactor, a heat exchanger for producing high-pressure steam from water due to the heat of reforming waste gases, a separator for condensing and separating water from synthesis gas, a liquid hydrocarbon synthesis reactor , a unit for separating the products of the synthesis of liquid hydrocarbons (for the desired product C ₅₊ , for by-products in the form of C _5- , СО ₂ , Н ₂ О, unreacted synthesis gas СО and Н ₂ ), a steam reforming reactor for a part of the exhaust gas, containing by-products.

The main disadvantages of the method and device according to patent RU 2247701 are:

1) carrying out the main stages of the process at various pressures from 1 to 4 MPa, which leads to the need to include several compressors in the technological scheme. This complicates the technological scheme and is accompanied by the corresponding capital costs and energy costs for their drive, which is unacceptable for small-tonnage production that pays off in a short time;

2) the use of an additional catalytic reactor for conducting steam conversion of exhaust gases, on the one hand, increases the yield of the final product and reduces CO ₂ emissions, and on the other hand, significantly complicates the technological scheme and leads to higher cost of the installation as a whole.

From patent RU 2387629 С07С 1/04, published on 04/27/2010, a method for producing synthetic hydrocarbons from hydrocarbon gases is known. The initial gaseous feedstock at a constant pressure of (0.8-3.0) MPa after purification from sulfur compounds is divided into two streams, one of which, together with a portion of the exhaust gases from the liquid hydrocarbon synthesis reactor, CO ₂ released from the exhaust flue gases, and H ₂ O in the form of steam is fed into a radial-spiral type reforming catalytic reactor for steam-carbon dioxide conversion, which is carried out at a temperature of (950-1050) ° C. The resulting synthesis gas is supplied as a heating medium to a steam boiler, then the synthesis gas is additionally cooled to a temperature of (20-40) ° С and moisture is separated, after which it is fed to a radial-spiral type liquid hydrocarbon synthesis reactor, where the synthesis reaction is carried out at temperature (180-220) ° С. The resulting mixture of liquid hydrocarbons is divided into commercial types of liquid hydrocarbons. A second stream of feed gas is mixed with another part of the off-gas from the liquid hydrocarbon synthesis reactor and fed to the burner of the catalytic reforming reactor as fuel. After that, moisture and carbon dioxide are released from the flue gases, which are then fed to the catalytic reforming reactor for steam-carbon dioxide conversion of gaseous hydrocarbon feeds, and the flue gases are cooled and removed from the installation. The condensate evolved from the synthesis gas and flue gases and the water obtained after separation of the products of the synthesis of liquid hydrocarbons are subjected to purification in a water treatment unit and sent to a steam boiler to produce the steam necessary for carrying out the carbon dioxide conversion of the feed gas.

The installation for implementing this method comprises a node for heat-utilizing equipment, a node for cleaning hydrocarbon gas from sulfur compounds, a radial-spiral type hydrocarbon gas reforming catalytic reactor, compressors, a steam boiler for producing carbon-dioxide vapor conversion of hydrocarbon gas, a radial-spiral type liquid hydrocarbon synthesis reactor, liquid hydrocarbon separation unit, recuperative heat exchangers, flue gas emission unit ₂ , water treatment unit.

The main disadvantages of the method and device according to patent RU 2387629 C1 of 04/27/2010:

1) the implementation of steam-carbon dioxide conversion in a catalytic reforming reactor requires an increased consumption of the original hydrocarbon gas for heating the reactor with flue gases, which complicates the design of the installation as a whole and leads to an increase in the ratio of the amount of the feedstock to the mass unit of the final product;

2) the adopted scheme for the conversion of the initial hydrocarbon gas (carbon dioxide) does not provide the possibility of wide control of the composition of the synthesis gas.

Closest to the claimed invention is a method for producing aromatic hydrocarbons, hydrogen, methanol, motor fuels and water from gas of an unstable composition of gas condensate and oil fields, described in patent RU 2362760 С07С 1/04, published July 27, 2009, including desulfurization of hydrocarbon gas, heating it flue gases, warming up the unit of heat-using equipment, the subsequent synthesis gas production by high-temperature reforming by its conversion with atmospheric oxygen, methane production from synthesis gas and followed by obtaining liquid hydrocarbons and water, distilling water from hydrocarbon residues.

The feedstock is an unstable hydrocarbon gas, having passed the sulfur removal unit, it is heated by the heat of the flue gases of the heat-using equipment unit and, after being compressed, is fed into the catalytic reforming reactor together with an oxidizing agent (atmospheric oxygen), where synthesis gas is generated (Н ₂ : СО ratio = 1.8-2.3: 1) at a temperature of (800-2000) ° C. The hot converted gas is sent sequentially to the heat exchanger and evaporator for cooling and heat recovery, and the water formed during the process is separated in a separator. Next, the synthesis gas is sent to the flow-type methanol synthesis catalytic reactors mounted in series. The operating temperature in the reactors is (220-280) ° C, the pressure is at least 5 MPa, the space velocity (2000-8000) h ^-1 . The resulting product (methanol) is collected in a separator.

Next, methanol, after heating in a recuperative heat exchanger, is pumped to the cascade of liquid hydrocarbon synthesis reactors at a temperature of (180-220) ° C and a pressure of (0.7-1.0) MPa. The reaction mixture leaving the synthesis reactors passes through a heat exchanger and a refrigerator and is separated in a separator. The recirculated gas streams are returned back to the liquid hydrocarbon synthesis reactor.

Liquid hydrocarbons enter the gasoline stabilization stripping column operating at a pressure of (1.2-1.4) MPa. The liquid hydrocarbon fraction flows into a tank to collect a marketable product.

Water is supplied to the distillation unit of the residues of light and heavy hydrocarbons, then for treatment, then to the water collection unit and to the storage tank for water.

The installation for implementing this method comprises a unit for preparing initial reagents, including a unit for heat-using equipment with a combustion chamber, a unit for cleaning hydrocarbon gas from sulfur compounds, a unit for compressing hydrocarbon gas, an unit for cleaning and compressing air, a unit for producing synthesis gas, including a methane synthesis reactor for synthesis -gas, recuperative heat exchangers, evaporator, separators, flare, methanol production unit, including methanol synthesis reactors, mounted after preferably, a unit for producing liquid hydrocarbons, including recuperative heat exchangers, a cascade of reactors for synthesizing liquid hydrocarbons, a refrigerator, a unit for stabilizing liquid hydrocarbons, including a reflux tank, refrigerators, a stripping column, a tank for collecting a marketable product, a unit for preparing water, including a tank for collecting reaction water, storage tank for collecting feed water, while all the installation units are hydraulically and pneumatically connected to each other and to intermediate tanks, and the output is formed gas during methanol processing is pneumatically connected to the inlet to the methanol processing reactor.

The installation is equipped with an automatic control system that provides trouble-free automatic shutdown in case of violation of the operability of individual elements.

This known method and device (patent RU 2362760) for producing aromatic hydrocarbons, hydrogen, methanol, motor fuels and water from gas of an unstable composition of gas condensate and oil fields are selected as prototypes of the proposed inventions, as closest to them in purpose, technical essence and achievable effect.

The main disadvantages of the method and device selected as prototypes:

1) in this installation, flue gases of a block of heat-using equipment, including a large amount of water vapor with a temperature of at least 350 ° C, are released into the atmosphere, which significantly changes the heat balance, harms the environment and makes the installation as a whole more expensive;

2) maintaining the nominal pressure in the system through the use of mechanical compressors of high power significantly increases the cost of installation and requires fixed costs for maintenance and repair of equipment;

3) an installation that implements a method for producing aromatic hydrocarbons, hydrogen, methanol, motor fuels and water from gas of an unstable composition of gas condensate and oil fields, due to its large tonnage, has a long payback period.

The objective of the claimed group of inventions is to reduce the cost of organizing the process of processing hydrocarbon gas, including gas of unstable composition, and the creation of a cost-effective small-tonnage plant for the production of liquid hydrocarbons, including with the aim of maximizing the use of gas reserves in remote, low-production, low-pressure fields, unprofitable for industrial applications by traditional methods, flared gases.

Technical result achieved:

1) reducing the cost of units and units of the installation related to the process of production of synthesis gas;

2) the creation of a small-tonnage installation with a capacity of at least 2 tons / day for liquid hydrocarbons (at least 5 tons / day for methanol) with a payback period of not more than 3.5 years;

3) the creation of a closed internal circulating water supply system that allows reuse of reaction water that has undergone a purification process. At the same time, the concept of recycling water supply to the installation completely eliminates the discharge of reaction water into the external environment, which allows us to solve environmental and economic problems: to reduce the water consumption of the installation as a whole, to reduce the loss of valuable components, to avoid charges for wastewater and fines for exceeding the maximum permissible concentrations.

To solve the problem and achieve a technical result, a group of inventions is claimed, which includes a method for producing liquid hydrocarbons from hydrocarbon gas and an installation for its implementation.

The inventive method for producing liquid hydrocarbons from hydrocarbon gas, accompanied by the simultaneous production of water, including its desulfurization, heating with flue gases a unit of heat-using equipment, the subsequent production of synthesis gas by high-temperature reforming by its conversion by atmospheric oxygen, production of liquid hydrocarbons and water, distillation of hydrocarbon residues from water, in which, according to the invention, the hydrocarbon gas and air are subjected to low temperature pre-reforming prior to high temperature reforming formation, and the stream of the reaction gas mixture after the pre-reforming reactor is divided into two streams, one of which is introduced into the feed line of the converted pre-reforming gas to the reforming reactor, and the second stream is sent before being fed to the reforming reactor to remove carbon dioxide, then the gas streams and liquid hydrocarbons are combined obtained from synthesis gas using a narrow-fraction catalytic system, while a radial filter is used in the pre-reforming, reforming and liquid hydrocarbon synthesis reactors iju reaction streams, further water is obtained from the flue gases from the waste pre-reforming gas and the process water losses are compensated by the water from the collecting tank that receives water released from the flue gases from the flue gas pre-reforming of liquid hydrocarbons synthesis process, optionally after reforming.

In conversion, oxygen enriched air may be used.

A device is also disclosed that is used to implement a method for producing liquid hydrocarbons and water from hydrocarbon gas, comprising a unit for preparing initial reagents, including a unit for heat-using equipment with a combustion chamber, a unit for purifying hydrocarbon gas from sulfur compounds, a unit for compressing hydrocarbon gas, an unit for cleaning and compressing air, synthesis gas production unit, including methane reforming reactor into synthesis gas, recuperative heat exchangers, evaporator, separators, flare oh, a unit for producing liquid hydrocarbons, including recuperative heat exchangers, a cascade of reactors for the synthesis of liquid hydrocarbons, a refrigerator, a unit for stabilizing liquid hydrocarbons, including a reflux tank, refrigerators, a stripping column, a tank for collecting a marketable product, a water preparation unit including a tank for collecting reaction water, storage tank for collecting feed water, in which, according to the invention, a hydrocarbon gas pre-reforming reactor and an assembly carbon dioxide from pre-reforming waste gases, the water treatment unit further comprises a unit for extracting reaction water from the flue gases of the heat-using equipment unit, and a stripping column of the unit for distillation of hydrocarbon residues from the reaction water in the water preparation unit is fed from a storage tank for collecting reaction water, a hydrocarbon compression unit the gas in the preparation unit of the initial reagents is made in the form of a steam-jet compressor, and the catalytic systems of the pre-reforming and reforming reactors nga in the synthesis gas production unit and the synthesis reactor in the liquid hydrocarbon production unit are made in the form of monolithic pipes with the implementation of radial filtration of reaction flows, while all the installation units are hydraulically and pneumatically connected to each other and to intermediate tanks, and the output of the synthesis gas formed during methane conversion, it is pneumatically connected to the inlet of liquid hydrocarbon synthesis reactors.

The air purification and compression unit in the initial reagent preparation unit can be equipped with an oxygen enrichment device for compressed air.

The set of features of the proposed method and installation allows you to:

1) to apply the input raw materials of unstable composition due to the process of low-temperature pre-reforming of hydrocarbons of the general composition (C ₁ -C _5- ). In this case, the primary heating of the feedstock to the pre-reforming reactor is realized due to heat recovery of the subsequent stages;

2) reduce the overall mass characteristics of the equipment for the production of synthesis gas through the use of combined autothermal conversion of a mixture of CH ₄ + CO ₂ + H ₂ O + O ₂ in a reforming reactor to produce a wide composition of CO + H ₂ mixture (100% conversion of the starting hydrocarbons into synthesis gas) and, as a result, rejection of the recycle of reaction flows;

3) to reduce the overall mass characteristics of pre-reforming, reforming and liquid hydrocarbon synthesis reactors (15-20) times by increasing their specific productivity by applying a radial filtration scheme for reaction flows on tubular block catalysts and by reducing the contact time of the starting components with the catalytic system (in reforming reactor, contact time not more than 50 ms, in a liquid hydrocarbon synthesis reactor - not more than 0.8 s);

4) reduce costs both in the procurement of basic equipment and in its operation due to the use of a steam jet compressor in the raw hydrocarbon gas pumping line in the unit for preparing initial reagents to nominal pressures (steam jet compressors do not have moving parts and are not expensive equipment compared to booster mechanical compressors). This ensures a reduction in energy consumption by 45% or more and, accordingly, a reduction in the cost per unit mass of the final product;

5) to reduce the consumption of high-quality energy in the processing of hydrocarbon gas into liquid hydrocarbons due to some increase in the amount of low-quality energy consumed by additional burning of primary raw materials in the burners of the heat-using equipment unit. This increases the ratio of the total volume of raw materials per unit of final product, but maintains a high profitability of the process due to the low cost of the feedstock;

6) reduce the overall mass characteristics of the installation as a whole and reduce its cost by using an internally replenished reverse water supply system with complete regeneration of reaction water;

7) reduce the cost of creating a plant for the production of liquid hydrocarbons due to the additional production of reaction water from the flue gases of the heat-using equipment unit during the combustion of raw gas and blow products; due to the use of water from pre-reforming waste gases, from the process of synthesis of liquid hydrocarbons, possibly after reforming.

8) to create an effective cost-effective installation for the production of liquid hydrocarbons from hydrocarbon gas, including gas of unstable composition, designed for low productivity, which will allow the use of plants of this type in low-yield, low-pressure fields, unprofitable for industrial applications by traditional methods.

The technological process is implemented in a block-modular design, which allows forming technological schemes in accordance with the capabilities of various fields, reducing commissioning time, and ensuring the mobility of the installation.

In FIG. 1 shows a block diagram of the claimed installation for the processing of hydrocarbon gas to produce narrow fraction liquid hydrocarbons and water.

The diagram shows how a recycled water system is implemented that allows reuse of reaction water that has undergone a purification process. Moreover, the concept of recycling water supply of the installation completely eliminates the discharge of reaction water into the external environment. The connecting lines in the diagram on the right describe the flow of reaction water to the water treatment unit (BPV), the connecting lines on the left describe the possibility of reusing reaction water after purification in the technological cycle in the corresponding devices of the source reagent unit (BPIR) and the synthesis gas production unit (BPGS) .

In FIG. 2 presents a process diagram of the claimed installation for the processing of hydrocarbon gas to produce narrow fraction liquid hydrocarbons and water.

The installation contains (Fig. 1 and Fig. 2) a block for producing initial reagents (BPIR), a block for producing synthesis gas (BPSG), a block for producing liquid hydrocarbons (BPZhU), a block for stabilizing liquid hydrocarbons (BSZhU), a block for preparing water (BPV) .

The initial reagent preparation unit (BPIR) includes a unit 1 of heat-using equipment with a combustion chamber, a unit 2 for cleaning hydrocarbon gas from sulfur compounds, a unit 3 for compressing hydrocarbon gas, and a unit 4 for cleaning and compressing oxygen-enriched air.

The synthesis gas production unit (BPSG) includes an evaporator 5, a recuperative heat exchanger 6, a hydrocarbon gas pre-reforming reactor 7, a refrigerator 8, a separator 9 for separating the reaction water and solid impurities from the pre-reforming waste gases, a carbon dioxide emission unit from the pre-reforming exhaust gases, including an absorber 10 and stripper 11, flare farm 12, recuperative heat exchanger 13, methane to syngas reforming reactor 14, a refrigerator 15, a separator 16 for cleaning the reforming waste gases from solid impurities and separating water.

The unit for producing liquid hydrocarbons (BPZhU) includes a recuperative heat exchanger 17, a cascade of liquid hydrocarbon synthesis reactors 18, and a refrigerator 19 for condensing liquid products.

The liquid hydrocarbon stabilization unit (BSU) includes a refrigerator 20 for cooling a mixture of condensed products and water, a reflux tank 21, a separation tank 22, a stripping column 23 for stabilizing liquid products, a refrigerator 24, a container 25 for collecting a marketable product.

The water preparation unit (BPV) includes a storage tank 26 for collecting reaction water, stripping columns 27, 28 of a hydrocarbon residue stripping unit, a storage tank 29 for collecting feed water, a unit for extracting reaction water and carbon dioxide from flue gases of a heat-using equipment unit 1, including a refrigerator 30, separator 31, absorber 32, stripper 33.

Below is a description of the proposed method and a description of the operation of the installation for producing liquid hydrocarbons from hydrocarbon gas.

The installation for processing hydrocarbon gas to produce liquid hydrocarbons and water contains a source reagent preparation unit (BPIR), which includes a unit 1 of heat-utilizing equipment, where the hydrocarbon gas is heated by flue gas heat and enters the reactor of the unit 2 for cleaning hydrocarbon gas from sulfur compounds.

The desulfurized gas is supplied to the steam jet compressor of the hydrocarbon gas compression unit 3 in order to maintain its nominal pressure in the system. In addition to the steam jet compressor, the hydrocarbon gas compression unit 3 contains a heat exchanger and a gas-liquid separator (not shown in the figure), where the flow is cooled and separated into a gas and liquid fraction, while the reaction water (water condensate) enters the tank 26 for collecting the reaction water of the preparation unit water (BPV). Further, the desulfurized compressed gas is heated by the heat of the flue gases of the unit 1 of the heat-utilizing equipment (not shown), saturated with water vapor from the evaporator 5, passes through a recuperative heat exchanger 6, where it is additionally heated by the heat of the subsequent stages and sent to the pre-reforming reactor 7 of the hydrocarbon gas of the synthesis gas production unit ( BPSG) after mixing with air or oxygen-enriched air from the unit 4 for cleaning and compressing air, also heated by the heat of the flue gases.

In the pre-reforming reactor 7, a catalytic conversion of hydrocarbon gas to methane takes place, where CO ₂ , H ₂ O, H ₂ are also formed. Next, the stabilized stream of the reaction gas mixture, passing through the heat exchanger 6, the evaporator 5 and the refrigerator 8 for cooling and heat recovery is divided into two streams, one of which (about 20%) is directly introduced into the feed line of the converted pre-reforming gas to the reforming reactor 14, and the second a stream (about 80%) is directed to a separator 9 to separate the multiphase stream of the pre-reforming process. In the separator 9, the converted pre-reforming gas is cooled, and the reaction water and solid impurities are separated. Before supplying methane to the reforming reactor 14 to the synthesis gas, carbon dioxide is additionally removed from this part of the preforming waste gases in the absorption and desorption apparatuses 10. Before feeding into the reforming reactor 14, gas flows are combined in front of the regenerative heat exchanger 13.

In the reforming reactor 14, the pre-reforming exhaust gases and the oxidizing agent (air) heated by the flue gases heating the heat-using apparatus unit 1 are subjected to high-temperature reforming, where, in addition to the synthesis gas, a (C ₂ -C ₄ ) fraction is additionally formed and a small amount of water may form.

Next, the hot converted gas (synthesis gas) is sent sequentially to the heat exchanger 13 for cooling and heat recovery. Then, after additional cooling in the refrigerator 15, the gas is purified from solid impurities, cooling and, in the case of water formation during the reforming process, the water is separated in the separator 16. In this case, the reaction water (water condensate) is supplied to the storage tank 26 for collecting reaction water water treatment unit (BPV).

The converted gas from the separator 16 passes through a recuperative heat exchanger 17 and is fed to the stage of liquid hydrocarbon synthesis in the cascade of synthesis reactors 18 of the liquid hydrocarbon production unit (BJCU). The catalytic systems of pre-reforming reactors 7, reforming 14 and synthesis 18 are made in the form of compact monolithic cermet cylindrical pipes with the implementation of radial filtration of reaction flows, i.e. in pre-reforming reactors 7 and reforming 14, a reaction gas stream is supplied along the central axis of the tubular catalyst system with radial gas filtration through the walls of the catalyst system to its outer surface, and in synthesis reactor 18, the reaction gas stream is supplied to the outer side surface of the tubular catalyst system in the radial direction through the catalyst bed to the central axis of the tubular catalyst system. The use of a radial filtering scheme for reaction streams increases the specific productivity of the reactors and reduces the contact time of the starting components with the catalytic system, which ensures optimal process conditions.

The reaction mixture exiting the synthesis reactors 18, consisting of hydrocarbons, water, and residual gas, passes through a heat exchanger 17 for heat recovery and a refrigerator 19 where liquid products are condensed, and in the refrigerator 20, the mixture of condensed liquid products is cooled to the required temperature.

A cooled mixture of condensed reaction products (liquid hydrocarbons and water) and residual gas from the refrigerator 20 is fed sequentially to the reflux tank 21 and the separation tank 22, where the liquid and gaseous phases are separated. Liquid products enter the stripping column 23 for stabilization, water into the storage tank for collecting reaction water 26, and the gaseous phase (purge gases) is sent to the burner in unit 1 of the heat-using equipment. Thanks to the burning of purge gases, inert gases (nitrogen) are continuously removed from the process cycle.

From the stripping column 23, liquid products flow through a refrigerator 24 into a container for collecting a commodity product 25, and the gaseous propane-butane fraction is sent to the burner in the unit 1 of the heat-using equipment.

The reaction water from the storage tank 26 enters the stripping column 27 and the stripping column 28 for sequential distillation of residues of light and heavy hydrocarbons. Purified water is supplied to the storage tank 29 to collect feed water for reuse in the production cycle (in the steam-jet compressor of the hydrocarbon gas compression unit 3 and in the evaporator 5).

The reaction water is extracted from the flue gases of the unit 1 of the heat-using equipment, from the pre-reforming process, from the process of synthesis of liquid hydrocarbons, while the technological losses of water are compensated by the water from the storage tank, which receives the water released from the flue gases, from the pre-reforming exhaust gases, from the liquid synthesis process hydrocarbons, possibly after reforming.

The possibility of carrying out the invention is illustrated by examples of its specific implementation.

Example 1

The proposed method for producing liquid hydrocarbons from hydrocarbon gas, accompanied by the simultaneous production of water, is implemented as follows.

The initial gaseous feedstock - hydrocarbon gas - is fed into the coil heater located in the unit 1 of the heat-using equipment, where it is heated by the heat of the flue gases to a temperature of (350-400) ° C and enters the reactor of the unit 2 for cleaning hydrocarbon gas from sulfur compounds. The sulfur content in the purified gas is not more than 0.5 mg / nm ³ . The desulfurized gas is supplied to the steam-jet compressor of the hydrocarbon gas compression unit 3, with the help of which its nominal pressure in the system is maintained (1.0-1.3) MPa. Water condensate from a gas-liquid separator (not shown in the figure) of a hydrocarbon gas compression unit 3 is supplied to a storage tank 26 for collecting reaction water.

After compression, the desulfurized gas is heated by the heat of the flue gases of the unit 1 of the heat-consuming equipment to (200-220) ° C, then it is saturated with water vapor in the evaporator 5 and heated in the heat exchanger 6 to 300 ° C due to the heat recovery of the subsequent stages and fed to the preformat reactor 7 after mixing with air (or oxygen-enriched air), which is supplied from the air purification and compression unit 4, also heated by the heat of the flue gases to a temperature of 300 ° C.

Due to the application of the low-temperature (280-300) ° С process of hydrocarbon gas pre-reforming, the possibility of using raw materials of an unstable composition is ensured. The technological scheme provides for automatic regulation of the ratio of the flow rates of raw gas and air (oxidizing agent) entering the preforming reactor 7. The ratio of CH ₄ : O ₂ : N ₂ = 1: 0.5: (0.5-3.75).

In the pre-reforming reactor 7 at a temperature of about 300 ° C., the catalytic conversion of the feed gas to methane takes place, where CO ₂ , H ₂ O, H ₂ are also formed. The presence of an excess amount of carbon dioxide in the gas stream is undesirable, therefore, at the next stage of the process, a part of the carbon dioxide is extracted from the preforming waste gases in the absorber 10 and stripper 11, while the gas stream is cooled in the refrigerator 8 and in the separator 9. Water condensate from the separator 9 is fed into a tank 26 for collecting reaction water.

In the reactor 14, the pre-reforming exhaust gases and air (oxidizing agent) are subjected to high-temperature (650-780) ° C reforming, the air being heated by flue gases heating the heat-using equipment unit 1 to a temperature of 420 ° C. By adjusting the ratio of CH ₄ : O ₂ you can control the composition of the synthesis gas.

In addition to synthesis gas (H ₂ : CO = 2: 1 ratio) in the reforming reactor 14, an additional (C ₂ -C ₄ ) fraction is formed and a small amount of water may form. In the case of water formation above acceptable values, a separator 16 is provided for separating multiphase flows of the reforming process.

In the separator 16, the gas is purified from solid impurities, cooled to a temperature of 40 ° C and a small amount of moisture is released, while water condensate is supplied to a container 26 for collecting reaction water for further purification and return to the technological cycle. A recuperative heat exchanger 17 passes from the separator 16 with a pressure of 1 MPa, where it is heated to 190 ° C and fed to the cascade of isothermal reactors 18 with radial filtration of the reaction flows.

The catalytic systems of pre-reforming reactors 7, reforming 14 and synthesis 18 are presented as block catalysts obtained by the SHS method. They are distinguished by selectivity, high mechanical strength, the ability to work in a wide temperature range and high catalytic activity, which is achieved due to the content of nanoparticles of rare earth metal oxides. The catalyst is activated once for the entire service life.

In the cascade of reactors 18 for the synthesis of liquid hydrocarbons using a narrow fraction catalyst system at a temperature of (200-250) ° C, a pressure of (0.9-1.10) MPa and a contact time of the synthesis gas with the catalytic layer of not more than 0.8 s, reactions occur with the release of heat, as a result of which hydrocarbons are formed from the reacted part of the synthesis gas and reaction water is a by-product. The catalytic system used in the cascade of reactors 18 for the synthesis of liquid hydrocarbons is narrow-fractional, since as a result hydrocarbons with a chain length of up to C ₁₂ will be predominantly synthesized, and the distribution of hydrocarbon fractions on a FeCoZr (IV) / SiO ₂ catalyst will be as follows: (C ₅ -C ₆ ) - 4.5% of the mass., (C ₇ -C ₈ ) - 7.5% of the mass., (C ₉ -C ₁₀ ) - 17% of the mass., (C ₁₁ -C ₁₂ ) - 19% of the mass. In this case, a high yield is obtained for the final (C ₅ -C ₁₀ ) product, instead of the total fractions of liquefied hydrocarbons requiring further processing. The high activity of this catalytic system ensures a high conversion of synthesis gas to liquid hydrocarbons in one pass of the reaction gas mixture without organizing a recycle.

Coming out of the synthesis reactors 18, the reaction mixture, consisting of hydrocarbons, water and residual gas, passing through the heat exchanger 17, transfers heat to the synthesis gas included in the cascade of synthesis reactors 18, is supplied to the refrigerator 19 and to the refrigerator 20, where the reaction mixture is cooled to 40 ° C and incomplete condensation into liquid hydrocarbons. A cooled mixture of condensed reaction products (liquid hydrocarbons and water) and residual gas with a temperature of 40 ° C and a pressure of up to 1 MPa is supplied to the reflux tank 21 and the separation tank 22, where the liquid and gaseous phases are separated.

The gaseous phase is directed to the burner of the unit 1 of the heat-consuming equipment, and liquid hydrocarbons enter the stripping column 23 for stabilization, where at a temperature of up to 70 ° С liquid products of С ₅ -С ₁₀ composition are isolated and condensed, and the gaseous propane-butane fraction C ₁ - With _{5 is} sent to the burner in the node 1 of the heat-using equipment.

Water is discharged into the storage tank 26 to collect the reaction water, then it enters the stripping columns 27 and 28 for sequential distillation of residues of light and heavy hydrocarbons. To heat the cube of the stripping column 27, the heat of the pre-reforming exhaust gas is used, to heat the cube of the stripping column 28, the heat of the reforming exhaust gas is used (not shown in the figure).

The purified water is fed into the storage tank 29 for collecting feed water for reuse in the production cycle. Possible water losses are compensated by water from the storage tank 26 for collecting reaction water, which receives water released from the flue gases of the unit 1 of the heat-utilizing equipment due to the additional combustion of raw hydrocarbon gas, from pre-reforming exhaust gases, from the process of synthesis of liquid hydrocarbons, possibly after reforming.

Example 2

An example of the operation of a pilot plant with a capacity of more than 2 tons of liquid hydrocarbons per day using input materials of known composition such as associated petroleum gas (APG).

On the coil heater of the unit 1 of the heat-consuming equipment, the feedstock is supplied - hydrocarbon gas (APG) at n.o. composition,% of the mass.

To start pre-reforming reactor 7 and reforming 14, it is necessary to supply a certain amount of air (or oxygen-enriched air), which will bring the temperature in the reaction zone to the required value: in the pre-reforming reactor up to 300 ° C, in the reforming reactor up to 650 ° C. After reaching certain temperatures, the increased air supply stops, and the system begins to work in the autothermal mode of incomplete oxidation.

Below are data on the effectiveness of the claimed group of inventions.

The consumption of raw hydrocarbon gas for the process is 260 kg / h.

The consumption of feed hydrocarbon gas in the burner is 63 kg / h.

Air consumption - 922 kg / h.

The volume of reaction water is 332 kg / h.

Productivity of the unit for (C ₅ -C ₁₀ ) products is 100 kg / h.

The conversion of primary raw materials to synthesis gas is (95-98)%, the selectivity for the target products (total fractions of liquefied hydrocarbons) is up to 20%, while the proportion of nitrogen in the synthesis products is up to 65%, the conversion of synthesis gas to liquid hydrocarbons is from 85 to one hundred%. The yield of the final (C ₅ -C ₁₀ ) product from the total fractions of liquefied hydrocarbons is 45%.

Claims (4)

1. A method of producing liquid hydrocarbons from hydrocarbon gas, accompanied by the simultaneous production of water, including, if necessary, its desulfurization, heating with flue gases a unit of heat-using equipment, the subsequent production of synthesis gas by high-temperature reforming by its conversion with atmospheric oxygen, production of liquid hydrocarbons and water, distillation from water of hydrocarbon residues, characterized in that the hydrocarbon gas and air are subjected to low-temperature pre-reforming before high-temperature reforming formation, and the stream of the reaction gas mixture after the pre-reforming reactor is divided into two streams, one of which is introduced into the feed line of the converted pre-reforming gas to the reforming reactor, and the second stream is sent before being fed to the reforming reactor to remove carbon dioxide, then the gas streams and liquid hydrocarbons are combined obtained from synthesis gas using a narrow-fraction catalytic system, while a radial filter is used in the pre-reforming, reforming and liquid hydrocarbon synthesis reactors iju reaction streams, further water is obtained from the flue gases from the waste pre-reforming gas and the process water losses are compensated by the water from the collecting tank that receives water released from the flue gases from the flue gas pre-reforming of liquid hydrocarbons synthesis process, optionally after reforming. 2. The method according to p. 1, characterized in that the conversion is carried out with oxygen enriched air. 3. Installation for producing liquid hydrocarbons and water from hydrocarbon gas, comprising a unit for preparing initial reagents, including a unit for heat-using equipment with a combustion chamber, a unit for cleaning hydrocarbon gas from sulfur compounds, a unit for compressing hydrocarbon gas, an unit for cleaning and compressing air, and a unit for producing synthesis gas comprising a methane reforming reactor into synthesis gas, recuperative heat exchangers, an evaporator, separators, a flare, a liquid hydrocarbon production unit, including cooperative heat exchangers, a cascade of liquid hydrocarbon synthesis reactors, a refrigerator, a liquid hydrocarbon stabilization unit including a reflux tank, refrigerators, a stripping column, a product collection tank, a water preparation unit including a reaction water collection tank, a storage tank for collecting feed water, characterized the fact that a hydrocarbon gas pre-reforming reactor and a carbon dioxide emission unit from the pre-reforming waste gases are additionally introduced into the synthesis gas production unit, bl The water preparation unit additionally contains a unit for extracting reaction water from the flue gases of the unit of heat-using equipment, and a stripping column for the unit for distillation of hydrocarbon residues from the reaction water in the water preparation unit is fed from the storage tank for collecting reaction water, the unit for compressing hydrocarbon gas in the unit for preparing the initial reagents in the form of a steam-jet compressor, and the catalytic systems of the pre-reforming and reforming reactors in the synthesis gas production unit and the synthesis reactor in the unit Radiation of liquid hydrocarbons is made in the form of monolithic pipes with the implementation of radial filtration of reaction streams, while all the units of the installation are hydraulically and pneumatically connected to each other and to intermediate tanks, and the output of the synthesis gas generated during methane conversion is pneumatically connected to the inlet of the liquid synthesis reactors hydrocarbons. 4. Installation according to p. 3, characterized in that the unit for cleaning and compressing air in the block for obtaining the initial reagents is equipped with an oxygen enrichment device for compressed air.

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