RU2744602C1 - Method for gasification of carbon-containing raw materials and device for its implementation - Google Patents

Abstract

FIELD: gasification of carbonaceous materials.

SUBSTANCE: invention relates to the field of gasification of carbon-containing raw materials and can be used in chemical, petrochemical, coke-gas, energy and other related industries, mainly for processing carbon-containing raw materials to obtain energy and process gases, obtaining synthesis gas by partial oxidation of a stream containing carbon. The method for gasification of carbon-containing raw materials includes partial oxidation of carbon-containing raw materials in an oxidation chamber in a mixture of oxygen-containing gas and water vapor, partial oxidation is carried out in a partial oxidation channel coaxially installed in a vertical oxidation chamber, and the supply of water vapor for partial oxidation of carbon-containing raw materials is carried out at the inlet and outlet of the vertical combustion chamber oxidation channel. The gas generator contains a housing, a burner device, a vertical oxidation chamber, collectors for supplying carbon-containing raw materials, water vapor and oxygen-containing gas, a pipe for removing gasification products, and a slag removal chamber. A partial oxidation channel is additionally introduced into it, which is coaxially located in the vertical oxidation chamber and is attached to the upper inner part of the housing, into which the burner device is built.

EFFECT: production of high hydrogen content in industrial gases, which makes it possible with high efficiency to carry out utilization of heavy oil residues at refineries to obtain high-quality motor fuels.

15 cl, 5 dwg

Description

The present invention relates to chemical, petrochemical, coke and gas, energy and other related industries, and can be used mainly for processing carbon-containing raw materials to obtain energy and process gases, in particular, for gasification of carbon-containing raw materials, obtaining synthesis gas by partial oxidation of the stream, containing carbon.

Methods for producing synthesis gas by partial oxidation are now well known in the applied technologies. Typically, a stream containing carbon (hydrocarbon) such as coal, brown coal, peat, wood, coke, soot or other gaseous, liquid or solid fuels, or mixtures thereof, is partially combusted in the gasification reactor, i. E. is partially oxidized using an oxygen-containing gas such as substantially pure oxygen or air, optionally enriched in oxygen, and the like, thereby obtaining a product stream including synthesis gas (i.e., CO and H ₂ ) and CO ₂ .

Coal gasification technologies are mainly divided into three types: fixed bed gas generators, such as gas generators manufactured by Lurgi AG (Germany, Frankfurt am Main) [1, pp. 161-167], fluidized or fluidized bed gas generators implemented using the U-GAS technology, Winkler (USA, Institute of Gas Technologies, Chicago) [1, pp. 167-173], and gas generators in parallel flow, according to the Shell process (jointly by Shell and Uhde, installation Buggenum, Netherlands) [1, pp. 189-191] and "Texaco" (USA, Texaco GP, Cool Water and Polk installations) [1, pp. 176-180].

Fixed bed gas generators have disadvantages due to the low throughput of a single device and the presence of expensive syngas and water treatment systems, and they also have inherent safety problems.

Fluidized bed gas generators have low efficiency due to low carbon conversion, difficulty in discharging dry bottom ash and carried away high fly ash.

These disadvantages are absent when using a parallel flow gasification process. In gasification devices in a parallel flow, it is possible to carry out partial oxidation of almost all types of carbon-containing raw materials, with the receipt of industrial gases with desired properties. In addition, such gas generators are small in size and can provide high productivity for the gasified feedstock.

The disadvantages of the parallel flow gasification process include the following:

1. Gasification of any types of solid and liquid fuels in a parallel flow can be efficiently carried out only when they are finely dispersed, as a rule, with a particle size of less than 75 microns. In this case, large fractions of raw material particles can significantly reduce the efficiency of the process and the quality of the gases obtained.

2. To obtain industrial gases with the highest possible yield of hydrogen (water gas, synthesis gas and their mixtures) during the gasification of solid and liquid fuels, it is necessary to use water vapor or a steam-oxygen mixture for the oxidation of raw materials, which creates problems for ignition of the mixture while maintaining the required optimal temperature conducting the process in the region of 900-1100 ° С [2, p. 26-27, p. 31].

The known scheme of a gas generator operating according to the "Koppers-Totzek" method [1, pp. 174-176], in which gasification is carried out at atmospheric pressure. According to the Koppers-Totzek technology, specially prepared crushed and dried fuel enters the fuel bunker, from where it is fed by metering screws to the mixing nozzles and then to the elliptical reaction chamber, in which there are two to four burner mixing nozzles located opposite each other. In burner nozzles, pulverized fuel is mixed with oxygen and water vapor in such a way that water vapor forms a steam jacket outside the dust-oxygen flame, thereby protecting the refractory lining of the reaction chamber from slagging, erosion and high temperatures inside the flame. The combustion temperature inside the torch is 1500–1700 ° C and its level is maintained depending on the ash melting temperature. Ash in liquid form is removed from the bottom of the reaction chamber into a special device, where it is cooled and granulated. The disadvantages of this gasifier include:

1. Increased oxygen consumption in comparison with other known steam-oxygen gas generators;

2. Reduced hydrogen yield due to high temperatures;

3. Low security, because even minor deviations from the nominal mode can lead to the formation of an explosive concentration of gaseous products inside the reaction chamber.

4. Increased requirements for structural materials for the construction of a gas generator due to high process temperatures.

There is also known a method of gasification of coal "Destec", which was originally developed by the Dow Chemical [1, pp. 180-183] to expand the fuel base by switching from natural gas to coal. For coal gasification, a two-stage in-line liquid ash removal gasifier has been developed. The fuel is fed into the reactor in the form of a water-coal slurry (coal / water = 60/40%) under high pressure generated by a pump. High-purity oxygen (95%) produced by a special unit is used as a gasifying agent. The gasifier operates at a pressure of 2.75 MPa and a temperature of 1371 ° C. However, the process temperature depends on the type of fuel used, and in the presence of more refractory ash, the process temperature increases due to liquid bottom ash removal. The coal-water slurry is fed to the bottom of the gasifier while mixing with oxygen. Partial oxidation of coal takes place, thus providing endothermic reactions in the zone of gasification with thermal energy. The slag formed in the first stage is removed into a water bath and then used in construction. The raw generator gas enters the upper lined part of the reactor, where a coal-water slurry is additionally introduced. In this part, the fresh fuel reacts with the generator gas obtained in the first stage of the process. At the second stage, the heat of combustion of the generator gas increases, and the ongoing endothermic reactions contribute to its cooling to a temperature of about 1038 ° C.

The disadvantages of this gas generator include:

1. The presence of technological problems with the use of coal-water suspension;

2. Reduced hydrogen yield due to high temperatures and high pressures;

3. Increased yield of carbon dioxide CO ₂ in comparison with other direct-flow gasifiers (ie, less caloric gas is obtained than in analogues);

4. Increased requirements for structural materials for the construction of a gas generator due to high process temperatures.

5. Use of highly purified oxygen as a gasifying agent.

Also known process "PRENFLO" (PRessurised Entrained-FLOw) with steam generation (PSG) from Thyssenkrupp AG [1, pp. 183-186], which is implemented at increased pressure on any type of solid fuel (coal, petroleum coke, biomass). The process is based on Koppers-Totzek technology. In the gas generator, the prepared fuel is gasified at a pressure of about 4 MPa.

The gasification temperature is higher than the ash melting temperature (1400-1600 ° C), which allows for liquid slag removal. The advantage of this process is the dry supply of fuel - gasification feedstock. Fine coal (80% of the volume less than 0.1 mm in size) is fed together with oxygen and steam through four burners located in the same horizontal plane at the bottom of the gas generator. The disadvantages of this gas generator include:

1. Reduced hydrogen yield due to high temperatures and pressures (in the chemical industry they are used only where a high hydrogen content in the process gas is not required);

2. High temperature and pressure cause increased requirements for the materials used in the construction of the gas generator and significant financial costs for its manufacture.

Also known is a gasifier of carbon-containing raw materials (RU No. 2237079, IPC C10J3 / 20, publ. 27.09.2004), which belongs to gas generators of carbon-containing raw materials and can be used in chemical, petrochemical, coke-gas, energy and other related industries for processing carbon-containing raw materials for the production of energy and process gases. The gasifier contains a vertical gasification chamber, a burner with nozzles for supplying carbon-containing raw materials and oxygen-containing gas, a collector for supplying water vapor, nozzles for supplying pulverized carbon-containing raw materials, a pipe for removing gasification products (in the lower part of the gasification chamber), a slag removal chamber, while it is equipped with a special block consisting of a burner located in the center of the block above the gasification chamber and nozzles located around the burner along the periphery of the block above the gasification chamber to create a steam curtain to protect the gasification chamber lining from overheating. The gasification chamber is a cylindrical pipe ending with a conical slag removal chamber, while the gasification chamber is conventionally divided into oxidizing and reducing parts. The process in the oxidation zone is carried out at a temperature of 1500-3000 ° C, and in the reduction zone by supplying steam, the temperature is reduced to 1000-1600 ° C.

The disadvantages of this gas generator include:

1. Reduced hydrogen yield due to high temperatures;

2. Reduced efficiency of the device when using the gasifier as a source of thermal energy, since the presence of free hydrogen and high carbon monoxide content indicate incomplete combustion.

3. The location of the gas outlet pipe in the lower part of the gasification chamber predetermines the ingress of significant volumes of slag and ash into the gas ducts and the gas distribution system, which can lead to a rapid failure of the gasifier.

Known adopted as the closest analogue method of gasification in the gas generator "PRENFLO" PDQ company Thyssenkrupp AG [1, pp. 186-189], more perfect than its predecessor "PRENFLO" PSG, which functions according to the "Koppers-Totzek" process. In this gas generator, finely dispersed coal dust is gasified in a mixture of oxygen and water vapor in a vertical oxidation chamber at a temperature of 1400-1600 ° C. Coal oxidation occurs in fact under adiabatic conditions, because the oxidation chamber is a channel coaxially located relative to the outer wall of the gas generator , separated from the outer wall by an annular space washed by the products of coal oxidation, which maintains the temperature in the oxidation chamber close to 1400-1600 ° C. The supply of coal dust and a mixture of oxygen and water vapor is carried out through 4 horizontal burners in the upper part of the oxidation chamber. The oxidation chamber passes into a rapid cooling chamber with water, into which water is injected through the holes located along the ring in the cooling chamber, cooling the oxidation products to a temperature of 200-250 ° C.

The closest to the claimed device is a gas generator [1, p. 186-189], which implements the specified prototype method, containing a manifold for supplying water vapor and oxygen to the burners, a collector for supplying a gas-coal mixture to the burners, an oxidation chamber that goes into a rapid cooling chamber water, which is a cylindrical pipe coaxially located inside the gas generator housing, ending in a conical ash removal chamber. An annular gap is located between the slag removal chamber and the central pipe of the rapid cooling chamber, through which the raw oxidation gas and water vapor leave the cooling chamber, then rise through the gap between the walls of the cooling chamber and the gas generator body and leave the gas generator into the pipe for withdrawing gasification products for further processing.

A sharp change in the movement of the gas flow in the rapid cooling chamber, leading to the fact that the downward movement of gases after passing the slotted gap between the pipe of the cooling chamber and the ash removal chamber is replaced by an upward movement, makes it possible to separate a significant amount of slag and ash into the conical ash removal chamber. The ash removal chamber is connected to the ash removal system.

The slag from the gasifier can be used as a building material.

The disadvantages of this gas generator include:

1. Reduced hydrogen yield due to high temperatures and pressures (in the chemical industry, these gas generators are used only where a high hydrogen content in the process gas is not required). Total hydrogen is not more than 22-32% vol. (as for all once-through gas generators based on Koppers-Totzek technology (Shell-Coppers process), while for Lurgi layer gas generators the hydrogen content in dry gas is 36-40%, for Winkler fluidized bed gas generators [1, p. 169- 170], the hydrogen content is in the range of 35-45% [4, p. 30];

2. High temperature and pressure cause increased requirements for the materials used in the construction of the gas generator and significant financial costs for its manufacture;

3. Increased specific oxygen consumption per 1 ton of gasified coal, as for all once-through gas generators based on Koppers-Totzek technology (540-650 m ³ ), while for Lurgi layer gas generators it is 220-300 m ³ , and for fluidized bed gas generators Winkler - 350 m ³ [4, pp. 30-33];

4. To ensure stable ignition and maintain a stable combustion of the mixture, in addition to the increased oxygen consumption in the oxidation chamber, a horizontal arrangement of burners is used, which does not allow reducing the process temperature to temperatures of 900-1100 ° C (optimal synthesis gas production temperatures), since at such temperatures (900-1100 ° C), the ash of the overwhelming majority of coals is in the solid phase, which means that it can accumulate on the wall of the combustion chamber, which leads to its slagging and further failure of the gas generator;

5. Too sharp cooling of gases to a temperature of 200-250 ° С does not allow obtaining additional hydrogen by means of the reaction

CO + H2O = CO2 + H2 + 10300 kcal, (1)

since already at a temperature of 800 ° C, the degree of decomposition of water vapor decreases compared to 1000 ° C by an order of magnitude, and for the same residence time and contact in 1 sec, the degree of conversion of water vapor at 800 ° C will be only 0.5% of the conversion at 1000 ° C [2, p. 29]. This means that at lower temperatures there will be no reaction at all, which is confirmed by an increase in the equilibrium constant of this reaction (1) at 500 ° C by a factor of 100 in comparison with 1000 ° C [3, p. 102].

The main objective of the invention is to provide an effective method of gasification in a parallel flow of carbonaceous feedstock, such as coal, brown coal, peat, wood, coke, soot or other types of gaseous, liquid or solid fuels, or their mixtures by the partial oxidation of hydrocarbonaceous feedstock in a mixture of oxygen-containing gas and water vapor and a device for its implementation in order to obtain the maximum possible yield of hydrogen during gasification of carbonaceous feedstock.

The technical result of the claimed invention is to obtain a generator gas with an increased hydrogen content. This achieves stability of ignition and maintenance of the required temperature of partial oxidation.

The claimed technical result is achieved by the fact that in the known method for gasification of carbonaceous feedstock, including partial oxidation of carbonaceous feedstock in an oxidation chamber in a mixture of oxygen-containing gas and water vapor, partial oxidation is carried out in a partial oxidation channel coaxially installed in the oxidation chamber, and the supply of water vapor for partial oxidation of carbonaceous feedstock is carried out at the inlet and outlet of the partial oxidation channel of the combustion chamber.

It is optimal to carry out partial oxidation in a flow of a mixture of oxygen and water vapor in the partial oxidation channel of the oxidation chamber at a temperature of 900-1100 ° C, which is provided by changing the volume of steam at the entrance to the partial oxidation channel.

It is advisable at the outlet of the partial oxidation channel of the oxidation chamber to maintain the temperature in the range of 800-1000 ° C, which is provided by changing the volume of steam at the outlet of the partial oxidation channel.

It is advisable to ignite a mixture of carbon-containing raw materials and a steam-oxygen mixture and maintain their stable combustion by supplying the partial oxidation channel of combustion products from a burner installed along the axis of the partial oxidation channel to the input of the partial oxidation channel.

It is preferable to choose the residence time of the combustion products in the oxidation channel longer than the combustion time of the maximum feed particle.

It is optimal to choose the geometric dimensions of the partial oxidation channel based on the ratio:

L ≥ (4 * G * T _b ) / (π * ρ (t _o ) * D ² ),

Where

L is the length of the partial oxidation channel;

D is the diameter of the partial oxidation channel;

G - mass arrival of oxidation products into the partial oxidation channel;

T _b is the combustion temperature of the maximum particle of carbonaceous feedstock;

t _o - design temperature of oxidation products in the partial oxidation channel;

ρ (t _o ) is the calculated density of oxidation products in the partial oxidation channel.

Solid fuels in the form of coal, brown coal, peat, wood, coke, soot, or gaseous and liquid fuels, or mixtures thereof, can be used as carbon-containing raw materials.

The technical result is also achieved by the fact that the known gasifier for gasification of carbonaceous feedstock, comprising a housing, a burner device, a vertical oxidation chamber, collectors for supplying carbonaceous feedstock, water vapor and oxygen-containing gas, a pipe for removing gasification products, a slag removal chamber, additionally contains a partial oxidation channel , which is coaxially located in the vertical oxidation chamber and is attached to the upper inner part of the housing, in which the burner device is built.

Optimally, the upper part of the body is made in the form of a removable cover, into which the burner device is built-in.

A pipe for withdrawing gasification products can be installed in the side part of the gas generator body, closer to the upper part of the gas generator.

It is optimal to make a gas generator for gasification of carbonaceous raw materials containing upper and lower steam collectors made in the form of hollow rings connected by downpipes, the axes of which are parallel to the axis of the outer casing, while the upper manifold is installed on the outer side of the gas generator cover, downpipes are located on the outer side of the partial oxidation, and the lower steam collector is located at the outlet of the oxidation channel, and is equipped with holes for steam outlet into the stream of partial oxidation products.

It is optimal to make the burner device in the form of a diffusion burner equipped with annular channels arranged coaxially around the diffusion burner and made with the possibility of supplying oxygen-containing gas, hydrocarbon feedstock and water vapor to the annular channels.

It is rational to make the inner walls of the oxidation chamber in the form of a coil, the upper outlet of which is connected to the upper steam collector through the hot steam distribution unit, and the lower outlet is connected to an external steam generator.

The inner walls of the oxidation chamber can be made in the form of coaxially arranged toroidal containers, which provide the possibility of supplying water vapor from the bottom of the oxidation chamber to the cover of the gas generator.

The partial oxidation channel can be made with external thermal insulation.

The claimed method for gasification of carbonaceous raw materials such as coal, brown coal, peat, wood, coke, soot or other types of gaseous, liquid or solid hydrocarbon fuels, or mixtures thereof, as well as a device for its implementation are unknown from the prior art, therefore, the claimed the solutions satisfy the “novelty” condition of patentability of the invention.

The analysis of the state of the art for compliance of the declared solutions with the condition of patentability of the invention "inventive step" showed the following.

In the proposed method for the gasification of carbon-containing raw materials such as coal, brown coal, peat, wood, coke, soot or other types of gaseous, liquid or solid fuels, or mixtures thereof by the method of partial oxidation in a mixture of oxygen-containing gas and water vapor in order to maximize the production of hydrogen , unlike known devices, in fact, the oxidation process is divided into 2 stages: first, partial oxidation is carried out under adiabatic conditions in a heat-insulated oxidation channel at optimal temperatures of 900-1100 ° C in a flow of a mixture of oxygen and water vapor, and then the resulting gases are further oxidized at the outlet channel for partial oxidation with water vapor only with maintaining the temperature in this zone within the optimal temperature range of 800-1000 ° C. In the proposed device for implementing the claimed oxidation method, in contrast to analogs, all processes are carried out under conditions that exclude a sharp increase in pressure in the reaction spaces. In addition, the claimed method allows for stable ignition and combustion in the resulting two-phase flow both on the surface of the particle and in the gas phase, due to the stable supply of additional thermal energy from the combustion products coming from the built-in burner in which liquid or gaseous fuel is burned. Combustion products from the burner enter the partial oxidation channel along the channel axis, mixing with the carbon-containing feedstock and the steam-oxygen mixture.

At the same time, the stability of ignition and maintenance of the required temperature in the oxidation channel is supported by the flow of thermal energy from the burner device built into the upper part of the gas generator housing when burning any fuel, regardless of the carbon-containing raw material supplied to the gas generator for oxidation, for example, using air oxygen, in contrast to the prototype other known means, in which the stabilization is supported by a high oxygen consumption for burning a part of the oxidizable carbon-containing raw materials, with obtaining high temperatures of 1400-1600 ° C and a pressure of 27-40 atm, and as a result, with a reduced yield of hydrogen. Conducting the process under optimal conditions and temperatures for gasification allows, in contrast to the prototype, where the burners are installed across the vertical axis of the gas generator (which leads to high temperatures when the flow of combustion products collide), to use inexpensive materials with significantly lower material consumption and heat resistance in the structure of the gas generator. Therefore, the claimed group of inventions satisfies the condition "inventive step"

The inventive method and device for gasification of carbon-containing raw materials are illustrated by drawings, where

in FIG. 1 schematically shows a general diagram of a gasifier for gasification of carbonaceous raw materials;

in FIG. 2 is a sectional diagram of a gas generator;

in FIG. 3 shows a diagram of the burner device of the gas generator;

in FIG. 4 is a schematic diagram of a gas generator with a coil for heating steam and cooling the wall of the casing;

in FIG. 5 schematically shows a diagram of a gas generator with a set of toroidal containers for heating steam and cooling the wall of the gas generator.

The inventive gasifier for gasification of carbon-containing raw materials contains a housing 1, an oxidation chamber 2, a housing cover 3 (Fig. 1), a burner device 4 (Fig. 4) with a diffusion burner 7, pipes for supplying oxygen 5 and a mixture of water vapor and carbon-containing raw materials 6, a pipe 8 for the removal of generator gases, a partial oxidation channel 9 with thermal insulation 10, with a collector 12 for supplying steam to the space at the outlet of the oxidation channel 9, as well as downpipes 13 (Fig. 2) supplying steam from the upper steam header 14 to the supply header steam 12. In the lower part of the body there is a ash removal chamber 11.

Figure 2 shows a section A-A (Figure 1) of the gas generator, which shows a variant of the arrangement of the steam supply holes 15 in the steam supply manifold 12. Figure 3 shows a diagram of a burner device 4 with a built-in diffusion burner 7 with an air supply channel 16 , with a fuel supply channel 17 (for example, fuel oil or gas fuel), with ignition electrodes 18, a mixing diffuser 19, with an oxygen supply channel 20 and a steam supply channel 21. FIG. 4 shows a diagram of the gas generator of FIG. 1, supplemented with a coil 22 for heating steam and cooling the thermal insulation of the wall of the housing 1 of the gas generator, a branch pipe 23 for introducing steam into the coil 22, a distribution unit 24 for supplying steam to a unit for mixing steam with a carbonaceous raw material 25 and into a collector 14, a supply pipe coal 26 to mixing unit 25. FIG. 5 shows a diagram of the gas generator according to FIG. 1, supplemented with toroidal tanks 27 for heating steam and cooling the thermal insulation of the wall of the gas generator body 1, a pipe 23 for introducing steam into a coil 22, a distribution unit 24 for supplying steam to a unit for mixing steam with a carbon-containing raw material 25 and into a collector 14, a pipe coal supply 26, rolls 28, connecting toroidal containers 27 with each other.

The inventive method and gasifier operate as follows.

The raw steam through the branch pipe 23 (Fig. 4) enters the coil 22, where it is heated by the exhaust gas from the generator through the pipe 8 of the outlet of the generator gases. Through the coil 22, steam enters the steam distribution unit 24, where it is divided into 2 streams. Part of the steam enters the mixing unit 25, where the steam picks up finely dispersed carbon-containing raw materials supplied through the nozzle 26, for example, coal dust, and the resulting vapor-coal mixture enters through the nozzle 6, for example, through an ejection device or a sluice (not shown in the drawing) into the burner device. The burner device is a combination burner 4 (Fig. 3) in which a diffusion burner 7 is located in the center for burning liquid or gaseous fuel in air. The combustion products of a diffusion burner with a temperature of 1500-2000 ⁰ С create the core of the gas flow swirling by the mixing diffuser 19 of the burner 7 and are picked up by mixing the flows of oxygen entering through the nozzle 5 into the channel 20 and the vapor-coal mixture entering through the nozzle 6 into the channel 21.

It is important and essential to obtain the maximum possible amount of hydrogen during gasification of hydrocarbon particles in a parallel flow is the solution of several contradictory problems, namely, the production of generator gas by an endothermic chemical reaction

С + Н2О = СО + Н2 - 31700 kcal (2)

with a significant loss of thermal energy, simultaneously with the process of burning out a part of carbon-containing particles in oxygen (in the total flow of steam and oxygen-containing gas) and maintaining the process temperature in the range of 900-1100 ° C.

To obtain the required result, it is necessary, first of all, to carry out the process at low pressure (for example, close to atmospheric), then, according to Le Chatelier's principle, the process according to (2) will be shifted to the right. Le Chatelier's principle establishes that in the case of an impact on an equilibrium system from the outside, with a change in any of the factors that determine the equilibrium position, the direction of the process in the system that weakens this effect is enhanced . Since as a result of reaction (2), 2 moles of gas are formed (CO and H2 instead of one mole of H2O), with an increase in pressure as a result of an increase in the volume of gases, then lowering the pressure in the reactor, it is possible to force the system to return to equilibrium, accelerating reaction (2) with the generation gases CO and H2. Conversely, when the pressure in the reactor increases, the pressure in the device decreases due to the slowing down of the reaction (2). Technically, this means that pressure must not be allowed to rise during the oxidation process, i.e. it is necessary to prevent an increase in gas-dynamic resistance to the movement of the gas flow, which means that structurally the channels through which the oxidation products move should not have sharp narrowings, and the combustion of carbon-containing particles should preferably be carried out during movement in the flow, and not in a closed chamber.

To maintain the required high temperature, it is rational to burn part of the carbon in oxygen according to the reaction

С + О2 = СО2 + 94,300 kcal, (3)

which at 1000 ° C occurs almost instantaneously, and with a decrease in temperature, its speed sharply decreases [1, p. 24]. However, to maintain reaction (2), a significant amount of water vapor is required, which takes away thermal power, and the flow of heat by reaction (3) occurs gradually as the particles burn out, therefore, it is rational to divide the water vapor into 2 parts, where the first part of the steam enters through the burner the device, and the second part of the steam supplied to the partial oxidation of the raw material enters the flow of the products of partial oxidation at the outlet of the oxidation channel, after burning out the particles of the carbon-containing raw material, into the space between the vertical wall of the gas generator body and the wall of the oxidation channel. In addition, the separation of the water vapor supply allows a controlled reaction CO + H2O = CO2 + H2 + 10300 kcal at the exit from the oxidation channel according to the formula (1)

with an increase in hydrogen in the generator gas. Since reaction (1) is exothermic, then, according to Le Chatelier's principle, as the temperature rises, the equilibrium will shift to the left (ie towards the starting products!), But for this reaction the boundary is a temperature of 1000 ° C (this can be seen from the dynamics of the equilibrium constant [ 3, p. 102] and according to experimental data [2, p. 30]). Those. the supply of water vapor at the outlet of the oxidation channel will allow reactions (1) to proceed and reduce the gas temperature to 700-800 ° C, preventing it from rising above 900-1000 ° C. Therefore, it is optimal to maintain the temperature at the exit from the oxidation channel within 800-1000C °.

To complete the redox reactions (2) in the partial oxidation channel, its geometric dimensions (diameter and length) must ensure the residence time of the burning particle in the channel not less than the time of its burnout (which significantly increases the efficiency of the process), and this significantly depends on the size combustible particles. So, for example, a particle of anthracite with a diameter of 100 microns burns in oxygen in 7.1 seconds, and with a diameter of 50 microns in 0.413 seconds [3, p. 210]. Knowing the particle size of the gasified feedstock and its hourly consumption, it is easy to calculate the geometric dimensions of the oxidation channel.

The most important condition for the stable operation of a gasifier with gasification of particles in the flow is stable ignition and combustion in the resulting two-phase flow, where combustion occurs both on the surface of the particle and in the gas phase, and for the stability of the process it is important that the flame propagation speed is higher than the speed of the two-phase flow. otherwise, the flame will break off and the oxidation process will stop. In known gasification gas generators, including the closest analogue of PRENFLO PDQ, this problem is solved by the fact that the combustion rate of coal particles is increased by increasing the pressure and temperature of the process by increasing the oxygen supply and burning more coal by reaction (3). And in addition, the residence time of the particles in the reactor is increased due to the arrangement of the burners perpendicular to the flow. It is important in the design of the prototype that the pressure increase in the oxidation chamber is achieved due to the narrowing at the exit from the oxidation chamber in the form of a rocket nozzle, which a priori requires liquid slag removal, and hence high temperatures, since otherwise, the narrowing channel will be quickly slagged.

In the claimed device, this problem is solved by the fact that in order to obtain a constant ignition source and stabilize the partial oxidation process, the burner device, preferably built into the cover of the gas generator, is a combined diffusion burner, in the center of which, along the axis, the actual diffusion burner for burning gaseous or liquid fuel, which is equipped with annular channels arranged coaxially around the built-in diffusion burner, made with the possibility of supplying oxygen-containing gas, hydrocarbon feedstock and water vapor to these annular channels. Those. the source of additional heat for igniting the mixture and maintaining a stable oxidation process in the proposed method is the heat of combustion products of liquid or gaseous fuel supplied along the stream of the reacting steam-oxygen mixture and carbon-containing raw materials. Such a scheme of the combustion process makes it possible to obtain stable ignition of a two-phase flow, to maintain its combustion until stable heat generation according to reaction (3), and to compensate for heat losses due to the reaction of carbon and carbon monoxide with water vapor. Thermodynamic calculations of variants of such a process show that the power of such a built-in burner in 10-25% of the power of carbon burned by reaction (3) is sufficient to obtain a stable process with a temperature in the flow not higher than 1100 ° C.

Thus, the claimed method allows for stable ignition and combustion in the resulting two-phase flow both on the surface of the particle and in the gas phase, due to the stable supply of additional thermal energy from the combustion products coming from the built-in burner, in which liquid or gaseous fuel is burned. Combustion products from the burner enter the partial oxidation channel along the channel axis, mixing with the carbon-containing feedstock and the steam-oxygen mixture.

By adjusting the flow rates of steam, coal and oxygen in the oxidation channel 9 (Fig. 4), a temperature of 900-1100 ° C is set, monitored by temperature sensors (not shown in the drawings). The second part of the steam from the distribution unit 25 through pipes 13 enters the steam supply collector 12 and through the holes 15 is fed into the space at the outlet of the oxidation channel 9, where additional oxidation of carbon monoxide to carbon dioxide takes place to produce hydrogen. The calculated amount of steam should provide a total of cooling to a temperature not exceeding 900-1000 ° C to prevent reverse reactions according to formula (1). The resulting generator gases through the pipe 8 for the outlet of the generator gases are fed for cooling and purification and further processing (for example, for organic synthesis or for a membrane separator with further supply of the obtained hydrogen for the hydrogenation of coal). The bulk of the slag and ash formed as a result of the combustion of coal enter the ash removal chamber 11, from where they are sent for utilization by the ash and ash removal system.

An example of a specific implementation

1. For the production of hydrogen for a coal hydrogenation plant, a prototype gas generator was built according to the scheme of Fig. 5 for the partial oxidation of coal. The parameters of the initial coal were determined: average ash content - 12%; humidity 8%; carbon content in the organic part of coal (OMU) - 77%; the hydrogen content in the WMD is 5%. The original coal was subjected to crushing, drying in a drum dryer and fine grinding on a crusher with a particle size of less than 100 microns (80% of particles less than 50 microns). Dry coal consumption was 1 ton per hour.

2. As a source of oxygen was chosen installation for obtaining oxygen from air with a capacity of 300 m ³ per hour or 390 kg per hour.

3. The volume of water for coal oxidation and the proportions of the distribution of steam volumes through the burner and the collector at the exit from the oxidation channel were selected from thermodynamic calculations of heat balances of chemical reactions of oxidation and reduction. A fuel oil burner with a thermal power of 200 kW was used as a diffusion burner built into the burner device, in which 20 kg of fuel oil burns per hour in 20x10.8 = 216 m ³ / h of air or in 276.5 kg / h of air.

4. Up to 150 kg of steam per hour was fed to the inlet of the partial oxidation channel through the burner device. The calculated temperature of the combustion products at the exit from the partial oxidation channel was 952 ° C, which fits into the optimal temperature limit of 900-1100 ° C.

6. The supply of steam from the manifold (item 12, Fig. 5) was carried out through 3 rows of holes with a spray angle between the rows of holes of 120 °. The volume of steam entering through the collector (item 12 in Fig. 5) was 250-300 kg per hour.

The steam volumes supplied through the burner and through the manifold were controlled according to data from 3 temperature sensors built in before the exit from the oxidation channel and data from temperature sensors built into the annular gap between the oxidation channel and the gas generator casing 20 cm above the exit from the oxidation channel ( 3 pcs).

The choice of the geometric dimensions of the partial oxidation channel (pos. 9, Fig. 6) was determined by the residence time of the combustion products in the oxidation channel. This value should preferably be greater than the combustion time of the maximum particle of the raw material. The gas generator received coal dust up to 50 µm - 80% and up to 80 - 90 µm - 20%. The combustion time of a particle with a size of 50 microns was 0.41 sec, and a particle of 100 microns was 7 sec. Under the condition of complete reaction of coal in a steam-oxygen stream, about 826 liters of gases per second were obtained at a temperature of 1000 ° C. When the diameter of the partial oxidation channel was chosen at 0.85 meters and the length of the oxidation chamber was 6 meters, the residence time of the particles in the oxidation chamber was 7.9 seconds, which exceeds the theoretical combustion time of a coal particle of maximum size.

The composition of gases (dry) in the regime with the maximum hydrogen yield was on average in volume%:

H2 - 52.3%,

N2 - 10.0%,

CO - 12.4%,

CO2 - 25.3%.

Oxygen consumption per 1 ton of dry coal was 300 m ³ per hour, steam consumption per 1 ton of dry coal was 370 - 430 kg.

From the source of information [4, page 31], which discloses the prototype installation according to the Shell-Coppers technology, the following average indicators are known:

H2 - 25.6%

CO - 65.6%

CO2 - 0.8%

CH4 - 8.0%

The oxygen consumption was 644m ³ per ton of dry coal, and the steam consumption was only about 100 kg per ton of dry coal. Obviously, the indicators of the hydrogen yield according to the proposed method and device are 2 times higher than that of the prototype, the oxygen consumption is 2 times less, and the process temperature is lower - 1100 ° C, compared to the prototype, in which the process takes place at a temperature of 1400-1600 ° С In the claimed device, the consumption of water vapor is almost 4 times higher, but the increased yield of hydrogen is precisely determined due to the decomposition of water.

The given example of a specific implementation of the proposed method and the device for its implementation shows that in the installation for the inventive gas generator, the results obtained for the hydrogen yield significantly exceed the indicators for the hydrogen yield in comparison with the prototype. In this case, the total consumption of steam for the partial oxidation of coal is 370-430 kg per 1 ton of coal. The oxygen consumption was 300 m ³ per ton of coal. The total hydrogen yield was about 65 kg per hour, while in the prototype it was about 32 kg per hour.

The claimed invention can find wide application for the gasification of carbonaceous feedstock, in connection with the provision of efficient gasification in a parallel flow of carbonaceous feedstock, such as coal, brown coal, peat, wood, coke, soot or other types of gaseous, liquid or solid fuels, or mixtures thereof in order to obtain generator gas with the highest possible hydrogen content. At the same time, the required parameters of the produced gas are easily regulated by changing the flow rates of oxygen, steam, gasified raw materials and the power of the built-in burner.

The gas generator can be used in the chemical, coal chemical and petrochemical industries (ammonia, methanol, synthetic fuels, etc.), coke oven gas, energy and other related industries for the processing of carbon-containing raw materials to obtain energy and process gases. The high content of hydrogen in the technical gases obtained in the claimed device will allow with high efficiency to carry out the utilization of heavy oil residues at oil refineries, with the receipt of high-quality motor fuels, and for the coal chemical industry, the claimed device can become the main basic device for the chemical processing of coals. Such a device is equally important both for the processing of coals by hydrogenation and for the production of synthesis gas from coals.

List of references:

1. Aleshina AS, Sergeev V. V. "Gasification of solid fuel": textbook. allowance. SPb .: Publishing house of Polytechnic. University, 2010 .-- 202 p.

2. Rambush N.E. (translated from English) "Gas generators" - M.-L .: GONTI, 1939. - 413p.

3. Pomerantsev V.V., Arefiev K.V. and others. "Fundamentals of the practical theory of combustion": Textbook for universities - L .: Energoatomizdat, 1986. - 312s.

4. Schilling G.-D., Bonn B., Kraus U. "Gasification of coal" - M .: Nedra, 1986. - 175p.

List of reference symbols

1. Housing

2. Oxidation chamber

3. Gas generator cover

4. Burner device

5. Oxygen supply pipe

6. Branch pipe for supplying a mixture of water vapor and carbon-containing raw materials

7. Built-in diffusion burner

8. Pipe for removing generator gases

9. Partial oxidation channel

10. Thermal insulation of the oxidation channel

11. Slag removal chamber

12. Bottom steam collector.

13. Downpipes

14. Upper steam collector

15. Steam supply holes in the manifold

16 Air duct

17. Channel of fuel supply.

18. Ignition electrodes

19. Mixing diffuser

20.Oxygen supply channel

21. Steam channel

22. Steam heating coil

23. Steam inlet to the coil

24. Unit for distributing steam supply.

25. Unit for mixing steam with carbonaceous raw materials

26. Branch pipe for supplying coal to the mixing unit.

27. Toroidal containers for heating steam

28. Kalachi for connecting toroidal containers.

Claims (23)

1. A method for gasification of carbon-containing raw materials, including partial oxidation of carbon-containing raw materials in an oxidation chamber in a mixture of oxygen-containing gas and water vapor, characterized in that partial oxidation is carried out in a partial oxidation channel coaxially installed in a vertical oxidation chamber, and the supply of water vapor for partial oxidation of carbon-containing raw materials are carried out at the inlet and outlet of the partial oxidation channel of the oxidation chamber. 2. The method according to claim 1, characterized in that the partial oxidation is carried out in a flow of a mixture of oxygen and water vapor in the partial oxidation channel of the oxidation chamber at a temperature of 900-1100 ° C, which is provided by changing the volume of steam at the entrance to the partial oxidation channel. 3. The method according to claim 1, characterized in that the temperature at the outlet of the partial oxidation channel of the oxidation chamber is maintained in the range of 800-1000 ° C, which is provided by changing the volume of steam at the outlet of the partial oxidation channel. 4. The method according to claim 1, characterized in that the ignition of a mixture of carbon-containing raw materials and a steam-oxygen mixture and maintenance of their stable combustion is carried out by feeding the partial oxidation channel of combustion products from a burner installed along the axis of the partial oxidation channel to the inlet of the partial oxidation channel. 5. The method according to claim 1, characterized in that the residence time of the combustion products in the oxidation channel is chosen longer than the combustion time of the maximum particle of the feedstock. 6. The method according to claim 1, characterized in that the geometric dimensions of the partial oxidation channel are selected based on the ratio: L ≥ (4 * G * T _b ) / (π * ρ (t _o ) * D ² ), Where L is the length of the partial oxidation channel; D is the diameter of the partial oxidation channel; G - mass arrival of oxidation products into the partial oxidation channel; T _b is the combustion temperature of the maximum particle of carbonaceous feedstock; t _o - design temperature of oxidation products in the partial oxidation channel; ρ (t _o ) is the calculated density of oxidation products in the partial oxidation channel. 7. The method according to claim 1, characterized in that solid fuel in the form of coal, brown coal, peat, wood, coke, soot, or gaseous and liquid fuels, or mixtures thereof, is used as the carbon-containing raw material. 8. A gas generator for gasification of carbonaceous feedstock by the method of claim 1, comprising a housing, a burner device, a vertical oxidation chamber, collectors for supplying carbonaceous feedstock, water vapor and oxygen-containing gas, a pipe for withdrawing gasification products and a slag removal chamber, characterized in that it additionally, a partial oxidation channel is introduced, which is coaxially located in the vertical oxidation chamber and is attached to the upper inner part of the housing, into which the burner device is built. 9. Gas generator according to claim 8, characterized in that the upper part of the body is made in the form of a removable cover, into which the burner device is built. 10 The gasifier according to claim 8, characterized in that the pipe for removing the gasification products is installed in the side part of the gasifier body, closer to the upper part of the gasifier. 11. The gas generator according to claim 8, characterized in that it contains upper and lower steam collectors made in the form of hollow rings connected by downpipes, the axes of which are parallel to the axis of the outer casing, while the upper manifold is installed on the outer side of the gas generator cover, downpipes are located on the outer side of the partial oxidation channel, and the lower steam collector is located at the outlet of the oxidation channel and is equipped with holes for steam outlet into the stream of partial oxidation products. 12. Gas generator according to claim 8, characterized in that the burner device is made in the form of a diffusion burner equipped with annular channels located coaxially around the diffusion burner and configured to supply oxygen-containing gas, hydrocarbon feedstock and water vapor into the annular channels. 13. Gas generator according to claim 8, characterized in that the inner walls of the oxidation chamber are made in the form of a coil, the upper outlet of which is connected to the upper steam collector through the hot steam distribution unit, and the lower outlet is connected to an external steam generator. 14. The gas generator according to claim 8, characterized in that the inner walls of the oxidation chamber are made in the form of coaxially arranged toroidal containers made with the possibility of supplying water vapor from the bottom of the oxidation chamber to the cover of the gas generator. 15. Gas generator according to claim 8, characterized in that the partial oxidation channel is made with external thermal insulation.

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