EA008269B1 - A method of converting coal into fuels - Google Patents

Abstract

The method is applicable to chemical and petrochemical industries for the production of synthesis gas. The method includes the preparation of the water-coal mixture and its gasification in two stages. The first stage (2) takes place in a vertical counter-flow pipe heat-exchanger (3) on a gasification column, and the second in a heating reactor (8) with production o synthesis gas and solid residues. A stage of catalytic conversion of the synthesis gas into motor fuels follows. The vapor-gas-coal mixture in the heat-exchanger (3) is subject to an action by modulated high-frequency fields in the frequency range from 1 MHz to 50 MHz at modulation frequencies in the range from 1 KHz to 200 KHz. In the reactor (8) , the vapor-gas-coal mixture is subject to the action of plasma from single-electrode high-frequency discharges at temperature 600-800°C. The synthesis gas obtained is subject to electrochemical purification from the compounds of sulphur and nitrogen, purification from chemical impurities, compressed and subject to conversion with the help of a polyfunctional catalyst containing oxides of iron, zinc and molybdenum in combination with a carrier, namely aluminium, its oxides and aluminium phosphate.The method is characterized in that the process of gasification of the vapor-gas-coal mixture in the reactor is performed in the presence of catalysts for the vapor conversion of carbon, which are deposited upon the thermoinsulating coating of the internal walls of the reactor.

Description

Application area

The invention relates to the thermal and thermochemical processing of coal into synthesis gas and can be used in the chemical and petrochemical industry for the production of synthesis gas of raw materials for the production of various types of chemical products and synthetic motor fuels.

State of the art

A known method of processing solid fuels, including the saturation of coal with hydrogen at high temperatures (above 400 ° C) and a pressure of 50-300 atm, followed by separation into liquid and solid intermediates. Liquid products are subsequently subjected to hydrogenation refinement to obtain components of high-octane gasoline, diesel, jet and gas turbine fuels, phenols, nitrogen bases and other products [1].

The disadvantage of this known method, as well as all known methods for producing motor fuels from coal by hydrogenation, is the need to use significant amounts of hydrogen. The amount of hydrogen needed is on average 3 times the amount of fuels obtained. This factor is a constraint for the wide development of such industries.

A known method of producing motor fuels from coal by producing synthesis gas (a mixture of CO + H ₂ ) from it with its subsequent processing into motor fuels [2].

According to this method, the mixture of hydrogen and carbon monoxide necessary for production is obtained in the process of treating coal with water vapor and oxygen.

There is also known a method for the thermal processing of solid fuels, including preliminary mixing of crushed coal with a gaseous oxidizing agent and subsequent gasification by supplying an electric arc to the zone so that the velocity vector of this mixture has a component parallel to the arc axis. In this case, the average temperature of the synthesis gas is maintained at a level of 1200-1700 ° C due to the regulation of the power of the electric arc. As the oxidizing agent according to this method, water vapor and oxygen are used in the ratio: water vapor 15-45%, and oxygen 8555% [3]. The use of oxygen as an oxidizing agent leads to the ballasting of synthesis gas with carbon dioxide, a product of the interaction of carbon and oxygen, and, in addition, a special installation is required to produce oxygen. All this leads to additional energy costs, since the synthesis gas must be cleaned, and the production and storage of oxygen in the required volume is also a very energy-intensive task.

Maintaining the temperature of the generated synthesis gas by controlling the power of the electric arc is ineffective, unreliable and difficult, since the heat in the reactor occurs both due to the combustion of coal in oxygen and due to the energy released by the electric arc, and only one heat source is regulated - the electric arc.

These shortcomings significantly reduce the technical and economic indicators and complicate the process as a whole.

A known method of processing coal into synthesis gas, comprising preparing coal in the form of a colloidal dispersed fuel system with an average surface particle size of the dispersed phase of not more than 1 μm, gasification of the resulting fuel mixture in one stage in a reactor with vertically arranged pipes to which the specified fuel mixture is fed while the temperature of the coolant in the annulus of the reactor is maintained in the range of 400-1000 ° C, and the temperature in the pipes is in the range of 200-800 ° C [4]. The disadvantage of this method is the low energy efficiency of the synthesis gas production process, namely:

the preparation of a colloidal dispersed fuel system is accompanied by grinding not only the organic but also the mineral part of coal with an average surface particle size of the dispersed phase of not more than 1 μm, which significantly increases the energy consumption for grinding coal as a whole;

independent heating of the coolant supplied to the annulus of the reactor to 1000 ° C in the presence of hot air cooling the synthesis gas after the tube cooler leads to unnecessary energy costs for heating the dispersed fuel system;

the use of a once-through tubular cooler to cool synthesis gas instead of countercurrent is also ineffective.

The recommended gasification temperature range of 200-800 ° C does not ensure the effective conduct of this process in the case of using low-reaction coals, such as anthracite.

In addition, the mass ratio of coal and water in the prepared colloidal dispersed fuel system is not indicated, which does not allow to determine the energy costs required to produce synthesis gas.

A known plasma-thermal method for processing coal into synthesis gas, including the preparation, heat treatment and gasification of coal using plasma in a plasma reactor, the gasification process is carried out in three stages, two of which occur in tubular heat exchangers, and the third, final, gasification stage is carried out directly in the volume of the plasma reactor simultaneously with the process of high-temperature pyrolysis in the presence of a reagent. Coal preparation is carried out by dispersing it in methanol water, to which surfactants alkylamides are added, and the resulting coal suspension is heated in the pipes of the first gasification stage to

- 1 008269

200-300 ° C in the stream of flue gases leaving the gasification column fed into the annulus of the reactor, and before the second stage of gasification, the coal suspension is heated to 9001100 ° C in the stream of synthesis gas discharged from the plasma reactor. As a reagent for high-temperature pyrolysis, water vapor is used that is injected into the reaction zone using plasma sources. The synthesis gas obtained in the plasma reactor is cooled and purified from impurities in a centrifugal bubbler using atmospheric air and water, while the atmospheric air is then used with a part of the synthesis gas in the furnace of the gasification column, and water is fed into a dispersing device for preparing a coal suspension [5].

The disadvantage of this method is the complexity of the technological process, carried out in three stages, with preliminary heating of the water-carbon suspension to 200-300 ° C, parallel combustion of part of the synthesis gas and the use of synthesis gas withdrawn from the plasma reactor heated to temperatures of 2200-2700 ° C. For the purpose of preheating and carrying out the first and second stages of gasification in the temperature range 900-1100 ° C, it is sufficient to use the heat accumulated in the synthesis gas discharged from the plasma reactor.

In the known method, the energy costs for the production of synthesis gas are also overestimated, which is associated with the introduction into the plasma reactor of a gas-vapor suspension consisting of carbon monoxide, carbon dioxide, hydrogen, water vapor and unreacted coal particles. Water vapor is used as a reagent in the plasma reactor, which leads to additional ballasting of gaseous gasification products with water vapor and simple hydrocarbons formed at high temperatures of 2200-2700 ° С.

The scheme of interaction between the plasma jets of steam and jets of the gasified mixture recommended in this method and the organization of the return of unreacted particles of the organic part of the coal to the reaction zone before they are completely converted into gas equally apply to the solid particles that make up the mineral part of coal that do not react with the steam phase and, as a result, accumulate in the high-temperature zone of the plasma reactor. Due to high temperatures and the length of their stay in the plasma reactor, the metal oxides that make up the mineral part of coal melt and their chemical interaction with carbon with the formation of metals, their carbides and carbon oxides becomes possible, which consumes a significant part of the energy and which, in general, lowers calorific value of synthesis gas due to its saturation with carbon oxides.

Closest to the claimed invention is a method for producing synthesis gas from a water-coal suspension [6], including the preparation and gasification of a water-coal suspension, the gasification of which is carried out in two stages, the first of which is carried out in a vertical countercurrent tubular heat exchanger of the gasification column, and the second stage in the reactor heating with microwave radiation (microwave reactor). According to this method, the preparation of a coal-water suspension is carried out by dispersing coal in the aqueous phase to a particle size of a solid phase of 10-30 μm with a mass concentration of the organic part of coal in a water-coal suspension of 32-48%. In the first stage of gasification, the resulting water-coal suspension under a pressure of 0.5-10 MPa is sent to the heat exchanger of the gasification column, where it is heated to a temperature of 500-700 ° C until a vapor-coal suspension forms. Next, this suspension is sent to a steam jet mill to regrind the particles of the solid phase to a finely dispersed state of 1-3 microns. The gas-vapor suspension, crushed to a given size, is fed to the second stage of gasification - to the microwave reactor heated by microwave radiation of the reactor, where it is heated to a temperature of 700-1500 ° C until synthesis gas is obtained. The obtained synthesis gas is cooled in the heat exchanger of the gasification column using a water-coal suspension entering the heat exchanger, and it is purified from ballast substances using water, which is used to prepare the water-coal suspension.

In contrast to the method described in patent KP2190661 [4], in this case, the gasification process is carried out in two stages instead of three, which simplifies the technology for producing synthesis gas. In addition, the process of preparing a water-coal suspension is carried out by grinding the source coal by dispersing it in the aqueous phase until the fused particles of the mineral and organic parts of the coal are revealed (to particle sizes of the solid phase of 10-30 μm, which avoids grinding the most durable and difficult to disperse the mineral part of coal to the size of the fine fraction is less than 1 μm and reduce energy consumption for the preparation of a water-coal suspension.

In this case, the mass concentration of the organic part of coal in the water-coal suspension is 3248%, which ensures low viscosity values of water-coal suspensions even with a particle size of coal particles in the range of 10-30 μm, which increases the efficiency of the synthesis gas production process.

In the first stage of gasification, the resulting water-carbon suspension under pressure of 0.5-10 MPa is heated in a heat exchanger to a temperature of 500-700 ° C, at which a gas-vapor suspension is formed, which intensifies the gasification process compared to gasification at atmospheric pressure.

The use of a steam-jet mill is not associated with attracting additional energy costs for grinding, since it consumes energy accumulated in an overheated vapor-gas suspension in the form of excess pressure (0.5-10 MPa) and an elevated temperature of 500-700 ° C. It should be noted

- 2 008269 that mainly porous particles of the coke residue of the organic part of coal are grinded both due to collisions and due to the destruction of porous particles due to the pressure drop inside the particle and the current pressure in the working chamber of the mill. Particles consisting of mineral inclusions of coal are crushed to a much lesser extent, since their porosity is practically absent.

The second stage of gasification is carried out in a microwave reactor, in which under the influence of microwave electromagnetic radiation, the entire reacting mass of the vapor-gas-coal suspension is directly heated to a temperature of 700-1500 ° C. As a result of this effect due to the absorption of microwave energy, the gasification process of vapor-gas-coal suspension is accompanied by further dispersion of solid material particles, which leads to an intensification of the gasification process and a more complete use of carbon.

The disadvantage of this method, selected as a prototype, is the process in such a high temperature range, which leads to an increase in energy costs, to reduce the economic efficiency of the process, to partial melting of the mineral part of coal, to the formation of soot.

Other disadvantages of the method are the low intensity of the synthesis gas production process and the technical complexity for introducing microwave radiation into the reactor by means of waveguides.

The objective of the invention is to provide a method for processing coal into fuels with increased efficiency in the process of producing synthesis gas from highly viscous coal-water fuels.

The technical essence of the invention

The goal is achieved by creating a method of processing coal into fuel, which includes the stage of preparation of the water-coal mixture and its gasification in two stages. The first stage is carried out in a vertical flow-through tubular heat exchanger of the gasification column, and the second stage is carried out in a heated reactor to produce synthesis gas and solid waste. Further, the method includes the stage of catalytic processing of synthesis gas into motor fuels. It is characteristic that the vapor-gas mixture in the heat exchanger is exposed to modulated high-frequency fields in the frequency range from 1 to 50 MHz with modulation frequencies in the range from 1 to 200 kHz. In the reactor, a gas-vapor mixture is exposed to a plasma of single-electrode high-frequency discharges at a temperature of 600-800 ° C. The resulting synthesis gas is subjected to electrochemical purification from sulfur and nitrogen compounds, purification from chemical impurities, compressed and subjected to conversion on a multifunctional catalyst containing iron, zinc and molybdenum oxides in combination with a carrier - aluminum, its oxides and aluminum phosphate.

The gasification of the gas-vapor mixture in the reactor can be carried out in the presence of carbon vapor conversion catalysts deposited on the heat-insulating coatings of the inner walls of the reactor.

An advantage of the invention is that the method of processing coal into fuels is characterized by increased efficiency in the process of producing synthesis gas from highly viscous coal-water fuels.

Description of attached figures

The invention is presented in more detail by way of an exemplary embodiment of an apparatus for implementing a method of processing coal into fuels. The figure shows a diagram of such an installation.

Exemplary Execution and Effect of the Invention

The installation shown in the figure is one of the possible implementations for implementing the method. Unlike the prototype, the gas-vapor mixture is pumped 1 into a vertical counter-current tubular heat exchanger 2 of the gasification column 3 and is further treated with high-frequency electromagnetic fields. The high-frequency energy is supplied to the gas-vapor mixture by means of metal rods 4 completely coated with dielectric materials (ceramics, quartz) 5. These metal rods 4 are directly connected to high-frequency generators 6, which in the operating mode transmit RF power to the gas-vapor mixture at the carrier frequency 1- 50 MHz and a modulation frequency of 1-200 kHz. In the indicated frequency range, the RF power is intensively absorbed by the vapor-gas-coal mixture. Thus, the process of gasification of coal-water fuel is controlled by changing the process temperature and intensifies the mixing of the treated mixture with modulated high-frequency electromagnetic waves.

The second stage of the method is associated with an additional process of gasification of a gas-vapor-coal mixture, which is supplied through pipelines 7 to a reactor 8 and in which the inner walls are coated with a special material based on a refractory coating, which has not only low thermal conductivity and heat capacity, but also catalytic properties in the steam carbon conversion reactor synthesis gas. The use of such a material, which is a catalyst, allows to accelerate the process of carbon gasification at relatively low temperatures (up to 400 ° C), which, ceteris paribus, allows you to increase the productivity of the synthesis gas production plant by 1.5-2.0 times.

In addition, in the reactor, additional processing of the vapor-gas mixture is carried out by means of a highly nonequilibrium plasma created by single-electrode high-frequency discharges,

- 3 008269 directly generated from the tip electrodes 9 inside the reactor, regardless of the chemical composition of the gas-vapor mixture and the thermal regime.

The supply of microwave energy to the rod tip electrodes is carried out by means of high-frequency generators 10. High-frequency generators operate at a frequency of 1-40 MHz and a modulation frequency of 0.5-50 kHz.

In this case, the gas-vapor mixture in the reactor is exposed to both single-electrode discharge plasma and high-frequency electromagnetic fields, resulting in the formation of fullerenes, fullerites, which increase the yield of synthesis gas from the treated mixture.

Distinctive features of the invention are:

the use of high-frequency energy in two stages of producing synthesis gas from a gas-vapor mixture;

the use of a highly nonequilibrium plasma of a single-electrode high-frequency discharge in the second stage of producing synthesis gas from a gas-vapor mixture;

the use of a refractory material for coating the inner walls of the reactor, which is not only resistant to the chemical and mechanical effects of the gas-vapor mixture, but also has high catalytic properties in the reaction of steam conversion of carbon;

the conversion of synthesis gas into synthetic motor fuels, carried out on a multifunctional catalyst containing iron, zinc and molybdenum oxides, aluminum, its oxides and aluminum phosphate.

The implementation of the claimed method has, in comparison with the prototype, a number of original technological methods and structural solutions of technological operations, which are as follows.

Inside the reaction gasification column 3, the synthesis gas production process is activated by modulated high-frequency fields, which allows to reduce the process temperature to 500-800 ° C.

In the reactor 8, a single-electrode high-frequency discharge is applied to the gas-vapor mixture by the plasma with the subsequent formation of fullerene-like compounds, which, in general, enhances the gasification of the treated mixture.

The inner walls of the reactor 8 are lined with material having not only heat-insulating, but also catalytic properties, which allows to increase the intensity of the process of producing syngas gas from a gas-vapor-coal mixture and thereby reduce its residence time in the reactor.

The process of gasification of gas-vapor mixture is as follows.

The prepared water-coal mixture with particles with sizes not exceeding 30 microns is pumped 1 under a pressure of 0.1-3.0 MPa into a vertical counter-flow tube heat exchanger 2 of the gasification column 3. In gasification column 3, the water-coal mixture is heated to 200-400 ° C until a vapor-gas coal is formed Suspension, which is processed by modulated high-frequency fields. The microwave power is supplied by metal rods 4 coated with dielectric material 5. The metal rods are directly connected to high-frequency generators 6, which operate at a carrier frequency of 1-50 MHz and a modulation frequency of 1-200 kHz.

The gasification process due to absorption of electromagnetic energy begins in the middle part of the reactor, and most intensively occurs in the upper part of the reactor at a temperature of 500-700 ° C.

Partially gasified vapor-gas-coal suspension through pipelines 7 is fed into the reactor 8 through a static mixer 11, where, under the influence of high-frequency fields and plasma of single-electrode discharges, the gas-vapor mixture is heated to a temperature of 500-800 ° C. The inner walls of the reactor 8 are lined with a thermally insulating coating, on the outer surface of which a carbon vapor conversion catalyst layer is applied.

The synthesis gas generated in the reactor 8 together with the ballast substances enters the annulus of the gasification column 3, where the water-carbon mixture entering the pipe part of the heat exchanger 2 is used as a cooler. After passing the heat exchanger, the synthesis gas is fed to a purification device 12, for example, a centrifugal bubbler an apparatus in which, due to direct contact with cooling water, the synthesis gas is cooled to ambient temperature and the ballast substances of the products are removed from it; gas fication (steam coal ash particles, hydrogen sulphide, carbon dioxide, etc.). The purified synthesis gas is compressed by a compressor and supplied to consumers through pipelines. Purified water is supplied to the recycled water pipeline. Ash gasification waste is removed from the bottom of the gasification column and sent for disposal. The mass ratio between water and the organic part of the solid phase of the coal-water mixture is determined from the condition that the water content is 10-20% higher than the amount of water required by the stoichiometric equation for the gasification of carbon with water vapor, and depends on the carbon content in coal [KP2233312]. When the mass fraction of carbon in the coal is in the range of 0.96-0.6, the mass concentration of coal in the water-coal mixture is equal to ~ 32-48%.

The resulting synthesis gas is sent for electrochemical and plasma chemical treatment at a temperature of ~ 600 ° C in order to maximize purification from sulfur and nitrogen compounds. Then the synthesis gas is cooled, purified from chemical impurities, compressed and sent to the hydrocarbon synthesis reactor at a temperature of 300 ° C and a pressure of 3 MPa. The synthesis of liquid hydrocarbons proceeds in the presence of

- 4 008269 functional catalyst containing oxides of iron, zinc and molybdenum in combination with a carrier - aluminum, its oxides and aluminum phosphate. The total yield of motor fuels is 190 g per 1 normal m ^{3 of} synthesis gas with a conversion of carbon oxides of 90%.

1. Chulkov VV Motor fuels: resources, quality, substitutes. M., 1998.

2. Setterfield C. Practical course of heterogeneous catalysis. M., World, 1984, 362 p.

3. GV2491490

4. KI2190661

5. VI2047650

6. VI2233312

Claims (2)

CLAIM 1. The method of obtaining motor fuels from coal, including the stage of preparation of a coal-water mixture and its gasification in two stages, the first of which is carried out in a vertical flow tube heat exchanger of the gasification column, and the second in a heated reactor, to produce synthesis gas and solid waste, as well as catalytic processing of synthesis gas into motor fuels, characterized in that the vapor-gas-carbon mixture in the heat exchanger is exposed to modulated high-frequency fields in the frequency range from 1 to 50 MHz and modulation frequencies in the range from 1 to 200 kHz, and in the reactor the vapor-gas mixture is exposed to the plasma of single-electrode high-frequency discharges at a temperature of 600-800 ° C, and the resulting synthesis gas is subjected to electrochemical purification from sulfur and nitrogen compounds, purified from chemical impurities, compressed and subjected to conversion on a polyfunctional catalyst containing oxides of iron, zinc, and molybdenum in combination with a carrier — aluminum, its oxides, and aluminum phosphate. 2. The method according to claim 1, characterized in that the gasification process of the vapor-gas-carbon mixture in the reactor is carried out in the presence of catalysts for the steam-reforming of carbon deposited on the heat-insulating coatings of the inner walls of the reactor.