UA81120C2 - Method for plasma thermal coal reprocessing and unit for realizing the same - Google Patents

Abstract

A method for plasma thermal coal reprocessing and a mechanism for realizing the same. The method provides in one technological aggregate realization in cyclically serial modes of processes of oxidation by processing coal of oxidation plasma jet for obtaining synthesis gas for subsequent obtaining electric energy and processes for reduction of metals from slag by periodic blowing slag by reduction plasma jet with purpose of obtaining precious components, at that water is used as one of plasma forming components. The unit represents two blocks - block for gasification and block for transforming energy, at that block for gasification consists of coupled gazifiers and receiver-cyclone, which provides equalizing pressure of synthesis gas in the system and its preliminary purification of dust either in oxidative and reduction modes, block for energy transformation comprises system of cooling and purification of synthesis gas, gas-turbine and stem-turbine plants with electric generators.

Description

Description of the invention

The interconnected group of inventions belongs to the technology of complex processing of solid fuel and to 2 designs of the device used in this, in particular to the technology of gasification of low-quality coal with low-temperature plasma and obtaining fuel synthesis gas for its subsequent (further) burning in power plants, as well as for obtaining metal products and can be used in many industries and utilities.

There is a known method of coal gasification, which includes the introduction of pulverized fuel by blowing a gasifying agent into the reaction chamber, in which, before the introduction of fuel into the reaction chamber, part of the fuel with an oxidizer is fed into the preparation chambers, made in the form of a muffle, in which the flow is previously generated low-temperature plasma, mix the flow of low-temperature plasma with pulverized fuel, heat and ignite the fuel, and support the combustion process in preparatory chambers made in the form of a muffle, after which the combustion products are sent to the reaction chamber, into which the main 72 flow of pulverized fuel and the agent , which gasifies, to carry out complete gasification of fuel, while air is used as an oxidizer, and superheated steam is used as a gasifying agent (Russian patent Mo2062287, application 04/14/94. Publ. Bull. Mo17, 1996).

The given method does not ensure complete processing of raw materials and is characterized by low productivity and complexity of the technological process.

The closest in technical essence and achievable result (prototype) is the plasma thermal method of processing coal into synthesis gas, which includes preparation, heat treatment and gasification of coal with the help of plasma, and the gasification process is carried out in three stages, two of which are carried out in tubular heat exchangers of the gasification column , and the third, final stage of gasification is carried out directly in the volume of the plasmatron simultaneously with the process of high-temperature pyrolysis in the presence of a reagent. At the same time, the preparation of coal c 22 is carried out by dispersing it in methane water, to which a surface-active substance - Ho) alkyl amides is added, and the obtained coal suspension is heated to 500-6009 K before the first stage of gasification in the flow of waste gases from the gasification column, and before the second during the gasification stage, it is heated to 1200-14009K in the flow of synthesis gas, which is removed from the plasmatron, while water vapor is used as a reagent during high-temperature pyrolysis, which is injected into the reaction zone with the help of a 3o plasma source, so that the velocity vector of plasma jets and the velocity vector of the gasified SM mixture are opposite to each other in the projection onto the plasmatron axis and coincide when they are projected onto the plane perpendicular to the plasmatron axis, and the synthesis gas obtained in the plasmatron is cooled and purified from the mixture in the centrifugal-drum apparatus using an atmospheric air and water, and atmospheric air is then used with part sy ntez-gas in the furnace device of the gasification column, and water is fed into: - w - d) dispersed device for the production of coal suspension (Russian Patent Mo2047650, application 28.09.93. Publ.

Bul. Mo31, 1995).

However, the known method is not economical enough, due to the fact that the preliminary preparation of raw materials and the multi-stage gasification process negatively affect the energy balance of the process as a whole. In addition, it does not ensure the complete extraction of valuable components from the raw materials, because it is intended exclusively for obtaining gaseous and liquid end products, while the removed molten slags contain a sufficiently high content of iron oxides (up to 2490) and silicon oxides (up to 4090). :z" A known energy-technological installation, which includes a lined gasifier for obtaining synthesis gas with a plasmatron installed in its lower part, and in the upper part - a dispenser for the supply of solid low-grade fuel and nozzles for the discharge of heated synthesis gas and the discharge of slag I.G. Artamonov. Processing of various so 15 organic wastes in a plasma chemical reactor. In the book Device! high-temperature technology. - M:

Moscow Institute of Chemical Engineering, Interuniversity Collection of Scientific Works. 1998, p. 63-64). Such use of the installation is intended exclusively for obtaining gas, while solid metal is used almost completely, and waste is ash and slag. The design of the specified installation does not provide sufficient flexibility of the technological process in relation to the production of other products. ko 20 The closest in terms of technical essence and achievable result (prototype) is a combined steam-gas plant with plasma-thermal gasification of coal, which includes two steam and one gas turbines with electric generators, a plasma-thermal gasifier with a coal supply unit, steam generators, a recovery boiler, a combustion chamber, a gas accumulator, a gas purification system, air and gas compressors and a catalytic reactor for the production of liquefied hydrocarbons, which is characterized by the fact that one of the steam generators is placed inside a plasma thermal gasifier, which has at least two plasmatrons on water vapor and

HF) is hydraulically connected to a steam turbine, a coal supply unit and one of the plasmatrons, the second steam generator 7 is installed inside the boiler-utilizer under a gas burner for burning synthesis gas and is hydraulically connected to a second steam turbine, a coal supply unit and a second plasmatron , while both steam generators are hydraulically connected to the heat utilization circuit, and the output of the gas turbine is placed inside the boiler-utilizer 60 in the flame zone of its gas burner and is hydraulically connected through the heat exchanger of the steam generator and the smoke extractor with the smoke pipe, while the system purification of synthesis gas is divided into two stages, connected to the plasma thermal gasifier by means of a steam ejector and to each other by means of a gas blower, of which one stage is wet and includes a venter-bubble apparatus with a recirculation circuit of liquid absorbent and a device for removing slag, and the second stage - dry and includes a replaceable block of catalysts with electrofilters and a device for removal of sulfur and its compounds, and the gas burner of the recovery boiler, the combustion chamber of the gas turbine, and the gas accumulator are hydraulically connected to the low-pressure gas compressor placed after the second stage of synthesis gas purification, and in the supply network of the catalytic reactor with synthesis gas, placed a high-pressure gas processor and a device for taking gaseous and liquefied gasification products, such as synthesis gas; gasoline (Patent of Russia

Mo2105040, application 03/29/95, publ. Bul. Mo5, 981.

The disadvantage of the known installation is the incomplete use of its internal volume, the limited field of application - the impossibility of its use in metallurgy. The slag formed in the gasification process is in a liquid state at the gasification temperature, and when the slag enters the lower part of the gasifier, where the temperature is significantly 7/0 lower than the gasification temperature, the liquid slag hardens and forms deposits at the bottom of the gasifier, which shortens its service life. In addition, the placement of steam generators inside the plasma-thermal gasifier and waste boiler in the event of the need for repair work on them leads to a stoppage of the installation as a whole. The installation provides for mandatory preliminary preparation of the initial fuel, which also reduces its efficiency.

The basis of the first of the group of inventions is the task of improving the method of plasma thermal /5 processing of coal, by creating a cycle of continuous processing of carbon-containing raw materials of any fractional composition, without its preliminary preparation and maximally using the reaction space of gasifiers, which ensures the production of synthesis gas, its use for obtaining electricity, ferrosilicon and fillers while preserving the cleanliness of the environment and reducing energy consumption.

The basis of the second group of inventions is the task of improving the installation for plasma thermal processing of coal by creating a cycle of uninterrupted and waste-free processing of raw materials due to the sequential placement of appropriate devices along the technological process and complete processing of raw materials in a single technological unit while preserving the cleanliness of the environment.

The first task is solved by the fact that in the method of plasma thermal processing of coal, which includes its gasification simultaneously with the process of high-temperature pyrolysis in the presence of a reagent that is injected with

In the reaction zone with the help of plasma sources, production of synthesis gas, cooling and purification of impurities of the obtained synthesis gas, according to the invention, gasification of coal in two gasifiers is carried out alternately i) in the plasma flow in such a way that after the end of the oxidation regime in the first gasifier, the plasma jet is turned off in it and the oxidation mode is continued in the second gasifier, while the cyclicity of the modes is repeated until the height of the liquid slag in one of the gasifiers is reached, which is determined by the dependence: во2 с и--- - тют

Rprrozp zho bis Z tb where A is the height of liquid slag; --

Sp - consumption of plasma-forming gas, kg/s; so rp 7 integrity of plasma, kg/m;

Рrozp 7" Density of the melt, kg/m ; ас - diameter of the output nozzle of the plasmatron, m; « d - acceleration of free fall, m/s2; жк 3.14, not s and the resulting liquid slag is treated with a reducing plasma jet and, after draining the metal and slag from the gasifier, it is reloaded with coal and the cycle is repeated, while water is used as one of the plasma-forming components.

The disclosed method of processing solid fuel provides in one technological unit the implementation of oxidation processes in cyclic and sequential modes by processing raw materials, for example, coal, using an oxidizing plasma jet to obtain synthesis gas for the subsequent generation of electricity, and - processes of recovery of metals from unreacted solid residue (slag) by periodically blowing the slag with a regenerative plasma jet in order to obtain valuable components, while water is used as one of the plasma-forming components. The given analytical dependence interrelates the ko 20 mode of operation of the plasmatron in the slag melt with the gas-dynamic parameters of the liquid bath of the melt. If this ratio is not met, gas-dynamic blocking of the plasmatron occurs, or melt m is splashed out of the slag trap and accumulates on the walls of the oxidation zone of the gasifier, forming vaults, bridges and cooling, as a result of which the process stops. Substitution of part of the reagent, which includes a gaseous oxidizer, for example, air or steam, for water, allows to increase the efficiency of the process and reduce the number of harmful emissions of MO." Since oxygen and hydrogen are formed during the plasma conversion of water,

HF) then free oxygen is spent on fuel oxidation, and hydrogen is used as an additional fuel element that increases the energy content of synthesis gas and preserves the cleanliness of the environment. o The second task is solved by the fact that in the installation for plasma thermal processing of coal, which contains a lined gasifier connected in the upper part with the fuel supply nodes, plasmatrons, a combustion chamber 60, a slag collector located in the lower part of the gasifier, a synthesis gas purification system , connected to a gasifier, a heat exchanger, gas and steam turbines with electric generators, a recovery boiler, according to the invention, the installation is equipped with an additional gasifier, which is also connected to the synthesis gas purification system, and a receiver - a cyclone, connected between itself in the upper part by a pipeline for transporting synthesis gas, the receiver - cyclone in the lower part is connected by inclined sawdust pipes with bo gasifiers, and plasmatrons are installed on both sides of the plane of the separating partition of the gasifier and slag catcher, respectively, in the wall of each gasifier and slag catcher oppositely each other, and in the slag catchers there are holes for draining the metal into the forks and depleted slag melt into the granulator, and the receiver is a cyclone through a synthesis gas supply pipeline, connected to a gas-cooling heat exchanger, one pipeline of which is connected to a steam turbine, and the other through a hot cleaning system and a ceramic filter connected to the combustion chamber of the gas turbine connected to the boiler-utilizer, while the additional output of the ceramic filter is connected through the unit of automatic supply of synthesis gas, the unit of additional cleaning and the unit of compression of synthesis gas with plasmatrons.

The structural solution of aggregates and nodes and their placement during the technological process ensured 7/0 the creation of residue-free complex processing of raw materials in a single technological unit while preserving the cleanliness of the environment.

The installation structurally consists of two blocks - a gasification block and an energy conversion block. The gasification unit consists of paired gasifiers lined with refractory bricks and a receiver-cyclone located in a hermetic metal case. The cyclone receiver ensures synthesis gas pressure equalization /5 V in the system and at the same time serves as the first stage of synthesis gas cleaning from dust.

Placement of oxidizing plasmatrons in the lower part of gasifiers allows efficient processing of fuel in counterflow mode. Plasmatrons installed in slag collectors provide operation in both oxidation and reduction modes, which makes it possible to use them additionally for fuel gasification, when the gasifier is turned on in the oxidation mode with a flexible and mobile system

Control capable of ensuring a quick transition from one operating mode to another.

The energy conversion unit includes a synthesis gas cooling and purification system, a gas turbine and a steam turbine unit with electric generators and a steam regeneration system, and flue gas purification and removal systems. The scheme for obtaining electricity and synthesis gas is quite flexible and simple.

The essence of the invention is explained by the drawing, which shows the scheme of the installation for plasma-thermal processing of coal.

The claimed method is carried out as follows. (8)

Plasma oxidizing jets blow coal in the volume of the first gasifier. As a result of gasification, synthesis gas is obtained, which is sent for further use in the production of electricity, and the liquid slag that is formed is accumulated in the slag trap until it reaches a height that is determined by the dependence of water cm

AVA A (85

Rpbrozp t ps 9 tb where A is the height of liquid slag; --

Sp - consumption of plasma-forming gas, kg/s; so rp 7 integrity of plasma, kg/m;

Рrozp 7" Density of the melt, kg/m ; ас - diameter of the output nozzle of the plasmatron, m; « d - acceleration of free fall, m/s2; жк 3.14, not s after which the obtained liquid slag is purged with renewable plasma and simultaneously carried out with » the oxidation cycle of carbon-containing raw materials in the second gasifier and, after draining the metal and slag from the first gasifier, it is loaded with raw materials and the cycle repeats. Depending on the brand of coal, its ash content, the cycles of operation of gasifiers in the oxidation mode of obtaining synthesis gas can be repeated two - four times before the liquid slag reaches the calculated height in one of the gasifiers, because such a cyclic-sequential mode allows, on the one hand, to continuously supply synthesis gas to the consumer, and - on the other hand, to process the liquid slag as it accumulates.

The coal processing unit contains gasifiers 1 and 2, united by a high-temperature receiver-cyclone 3, and supplied in the upper part with loading devices 4, and in the lower side part of coal 20 with plasmatrons 5 located opposite to each other. The lower part of gasifiers 1, 2 connected to liquid slag slag catchers 6, in the side wall of which plasmatrons 7 are installed. In slag catchers 6 m, there are flights 8 for draining the metal ligature in the pouring vessel 9, and the depleted slag melt - into the granulator 10.

Plasmatrons 5 and 7 are connected to power sources 11, which provide the necessary energy-physical 22 Characteristics of the arc discharge, to the compressor 12 of the supply of plasma-forming air and to the centrifugal

F! pump 13 supplying cooling and plasma-forming water. The energy conversion unit includes a system of cooling and fine purification of the obtained synthesis gas, which contains a heat exchanger 14 connected at the outlet of the receiver-cyclone o C, connected to a steam turbine 15, and then sequentially - to a hot purification system 16, a ceramic filter 17, combustion chamber 18 of the gas turbine 19. On the axis of the gas turbine 19 there is an electric generator 20 60 and a compressor 21 for supplying gas to the combustion chamber 18. The gas turbine 19 is connected to a recovery boiler 22. For the operation of plasmatrons in regenerative mode, a block consisting of from the serially connected node 23 of automatic supply of synthesis gas, the node of intensive cooling 24, the node of additional purification 25 and the node of compression of synthesis gas 26, connected to plasmatrons 7. because the installation works in this way.

Coal is loaded from above into gasifier 1 by device 4. Plasma-forming air is supplied to plasmatrons 5 and 7 by compressor 12, and plasma-forming and cooling water is supplied by external pump 13. With the help of the power source 11, arc discharges are excited and plasmatrons 5 and 7 are started. The layer of raw materials is blown by plasma oxidizing jets, and the synthesis gas formed during the gasification process enters the high-temperature receiver-cyclone 3, in the lower part of which, through a pipeline equipped with non-return valves the system of dust removal in gasifiers 1,2 has been implemented. Receiver-cyclone Z is designed to equalize the synthesis gas pressure in the system and at the same time serves as the first stage of purification of synthesis gas from dust. At this time, the raw material is loaded into the gasifier 2 by the loading device 4. After the completion of the gasification process in the first gasifier, the plasmatrons 5 and 7 are turned off and turned on in the gasifier 2. Then the process is repeated.

Synthesis gas heated to a temperature of 1100-130092С from the high-temperature receiver-cyclone Z under an excess pressure of 1-5 atm enters the gas-cooling heat exchanger 14, where it is cooled to a temperature of x5402С. From the heat exchanger 14, steam enters the steam turbine 15 to generate electricity.

Cooled in the heat exchanger 14 to a temperature of -5402C, the synthesis gas enters the hot cleaning system 16, where sulfur in the fluidized bed is adsorbed by zinc titanate, which is partially removed for regeneration.

After hot degreasing, volatile dust is removed from the syngas in the candles of the ceramic filter 17, and then the gas enters the combustion chamber 18 of the gas turbine 19. An electric generator and a compressor 21 are located on the axis of the gas turbine 19, which supplies air to the combustion chamber 18. After the gas turbine 19 combustion products 20 are sent to the boiler-utilizer 22 and then discharged into the chimney. The steam obtained in the recovery boiler 22 is fed to the steam turbine 15 to generate electricity. The electricity produced in gas and steam turbines is partially used for own needs (operation of plasmatrons, pumps, compressors, etc.) and is supplied to the network to the consumer.

Depending on the grade of coal, its ash content, the cycles of operation of gasifiers 1 and 2 in the oxidizing mode of obtaining synthesis gas can be repeated 2-4 times until the liquid slag reaches a thickness of L in one of the gasifiers. When the level of slag of a given thickness is reached, plasmatrons 7, which are placed in the slag catcher of the gasifier, are switched to the regenerative mode of operation. For the operation of plasmatrons 7 in the slag recovery mode, the synthesis gas purified in the candles of the ceramic filter 17 passes through the automatic supply node 23 to the intensive cooling node 24, then to the additional purification node 25 and the compression node 26, from which (a) is purified and cooled to temperature - 302 and compressed to 3-6 atm synthesis gas is fed to plasmatrons 7.

Iron and silicon are recovered from the slag under the action of regenerative plasma jets. The resulting ferrosilicon metal ligature is poured into the hopper 9 through the fly 8, and the depleted liquid slag into the granulator 10. "--

The term of the metal recovery process does not exceed 20-40 minutes and therefore fits into the technological cycle "- gasification. After draining the metal and slag from the slag collector, a fresh portion of coal is loaded into the gasifier, and plasmatrons 5 of the gasifier and plasmatrons 7 of the slag collector start working in the oxidation 00 mode. After the end of the gasification process in this gasifier, the plasmatrons in the second gasifier are turned on, and then the process is repeated.

The performed calculations and experimental results show that during plasma thermal gasification of coal "emissions into the atmosphere are ten times less than during any other processes based on burning coal. This is due to the fact that during plasma gasification, in contrast to known combustion processes, which take place at a 5-6 times ratio of air to coal, the amount of oxidizer is set clearly dosed and only to support the reaction of incomplete oxidation of carbon. Thus, with an air/water weight ratio not exceeding 0.3, the concentration of nitrogen in the oxidizing plasma does not exceed 2095, and therefore the output of nitrogen and nitrogen compounds in the final product does not exceed 1095, with almost a complete absence of CO and HO.

It was experimentally established that with the power of the proposed installation up to 0.7 MW and the power of three (ee) simultaneously working plasmatrons up to 0.6 MW when processing 1000 kg/h. grade G coal output is provided - 100Okg/h. heated to 10009 synthesis gas, delivery to the network of 1500 kW-h. of electricity, output up to 4Okg/h. ferrosilicon and up to 150 kg/h. lightweight filler for reinforced concrete and other structures. - The declared method of thermal processing of coal and the steam-gas plant for its implementation allow

Ge 20 effectively process the original carbon-containing raw materials of any fractional composition with the maximum extraction of high-quality finished products with minimal impact on the environment.

Claims (1)

The formula of the invention is 1. A method of plasma thermal processing of coal, which includes its gasification in a gasifier simultaneously with the process of high-temperature pyrolysis in the presence of a reagent that is injected into the reaction zone with the help of plasma sources, production of synthesis gas, cooling and purification of impurities of the obtained synthesis gas , which differs in that coal gasification in two gasifiers, one of which is additional, is carried out 60 times in the plasma flow in such a way that after the end of the oxidation mode in the first gasifier, the plasma jet is turned off in it and the oxidation mode is continued in the second gasifier, with this cycle of regimes in the gasifiers is repeated until the height of the obtained liquid slag is reached in one of the gasifiers, which is determined according to the dependence: 2 ' 65 A A Op Eroz p ysE where 4 is the height of the liquid slag; St - consumption of plasma-forming gas, kg/s; Рp 7 plasma density, kg/m; - melt density, kg/m; Shrot ar - the diameter of the output nozzle of the plasmatron, m; s- acceleration of free fall, m/s; -- 3.14, and the slag is treated with a restoring plasma jet and, after draining the metal and slag from the gasifier, it is reloaded with coal and the cycle is repeated, while water is used as one of the plasma-forming components. /5 2. Installation for plasma thermal processing of coal, which contains a lined gasifier, connected in the upper part to the fuel supply units, plasmatrons, a combustion chamber, a slag catcher, located in the lower part of the gasifier, a synthesis gas purification system connected to the gasifier , a heat exchanger, gas and steam turbines with electric generators, a recovery boiler, which is distinguished by the fact that the installation is equipped with an additional gasifier, a receiver-cyclone, interconnected in the upper part by a pipeline for transporting synthesis gas, a receiver-dcyclone in the lower part with is connected by inclined sawdust ducts with gasifiers, and plasmatrons are installed on both sides of the plane of the separating partition of the gasifier and slag trap, respectively, in the wall of each gasifier and slag trap, opposite to each other, and in the slag trap of each of the gasifiers there are outlets for draining metal in the mold and depleted slag melt into the granulator, and the receiver-cyclone through the pipeline supply of synthesis gas is connected to the gas-cooling heat exchanger, one pipeline of which is connected to the steam turbine, and the other - through a hot cleaning system and a ceramic filter, connected to the combustion chamber of the gas turbine, connected to the boiler-utilizer , while the additional output of the ceramic filter is connected through the unit of automatic supply of synthesis gas, the unit of additional purification and the unit of compression of synthesis gas with plasmatrons. "c) c "- "- d) - and? (ee) - - name) (42) name) 60 b5