WO2006075978A1

WO2006075978A1 - Method for organic fuel plasma-thermal processing and device for carrying out said method

Info

Publication number: WO2006075978A1
Application number: PCT/UA2005/000032
Authority: WO
Inventors: Anatoly Timofeevich Neklesa
Original assignee: Anatoly Timofeevich Neklesa
Priority date: 2005-01-17
Filing date: 2005-07-21
Publication date: 2006-07-20
Also published as: RU2294354C2; UA81120C2; RU2005113825A

Abstract

The inventive method consists in processing coal in a single technological plant by means of an oxidising plasma jet in cyclical-sequential modes in such a way that a synthetic gas is obtained and used for producing electric power and for recovering metals from slag by periodically blowing said slag with a reducing plasma jet, wherein water is used in the form of a plasma-forming component. The inventive plant consists of coupled gasifiers (1, 2) and a cyclone manifold (3). Plasmotrons (5, 7) are arranged in each gasifier (1, 2) on both sides of a partition separating the gasifier and a slag collector (6) oppositely to each other. The cyclone manifold (3) is connected, by means of a pipeline, to a gas-cooling heat exchanger (14), one end of which is connected to a steam turbine (15) and the second end to the combustion chamber (18) of a gas turbine (19) through a gas preparation unit. The operation of the plasmotrons in a reducing mode is carried out by means of a unit consisting of in series-connected a synthetic gas automatic supplying unit (23), cooling unit (24), cleaning unit (25) and a synthetic gas compressing unit (26).

Description

The method of plasma-thermal processing of fossil fuels and installation for its implementation.

An interrelated group of inventions relates to the technology of complex processing of solid fuel and the design of the device, which is used in this case, in particular to the technology of gasification of low-quality coal with low-temperature plasma to produce combustible synthesis gas for its further combustion in power plants, as well as for the production of metal products and can be used in many industries and utilities.

A known method of gasification of coal, including the introduction of pulverized fuel by blowing and a gasifying agent into the reaction chamber, in which, before the fuel is introduced into the reaction chamber, part of the fuel with the oxidizing agent is fed into the preparation chambers made in the form of a muffle in which a low-temperature plasma stream is pre-generated, mixing the flow of low-temperature plasma with pulverized fuel, heating and igniting the fuel, and supporting the combustion process in preparatory chambers made in the form of a muff I, then the combustion products are sent to the reaction chamber, into which the main stream of pulverized fuel and a gasifying agent are introduced tangentially for the complete gasification of the fuel, with air being used as an oxidizing agent and superheated steam as a gasifying agent (Russian Patent Na 2062287, 14.04.94., Publ. Bul. JVbP, 1996).

The specified method does not provide complete processing of the feedstock and is characterized by low productivity and complexity of the process.

The closest in technical essence and the achieved result (prototype) is a plasma-thermal method for processing coal into synthesis gas, which includes the preparation, heat treatment and gasification of coal using 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 the gasification stage is carried out directly in the plasma torch volume simultaneously with the high-temperature pyrolysis process in the presence of a reagent. In this case, the preparation of coal is carried out by dispersion in methane water, to which surfactants are added - alkylamides and the resulting coal suspension is heated before the first gasification stage to 500-600 ° K in the stream of flue gases leaving the gasification column, and before the second gasification stage they are heated to 1200-1400 ° K in the stream of synthesis gas discharged from the plasma torch, while water vapor, which is injected into the reaction zone using plasma, is used as a reagent for high-temperature pyrolysis source, so that the velocity vector of the plasma jets and the velocity vector of the gasified mixture are opposite to each other when projected onto the axis of the plasma torch and coincide when they are projected onto a plane perpendicular to the axis of the plasma torch, and the synthesis gas obtained in the plasma torch is cooled and purified from the mixture in a centrifugal - a drum apparatus using atmospheric air and water, and the atmospheric air is then used with a portion of the synthesis gas in the furnace of the gasification column, and water is fed into a dispersing device for preparing method of coal suspension (Russian Patent N22047650, decl. 09/28/93, Publ. Bull.: N ° 31.1995) However, the known method is not economical enough, since the preliminary preparation of the feedstock and the multi-stage gasification process adversely affect the energy balance of the process as a whole. In addition, it does not provide complete extraction of valuable components from the feedstock, as it is intended solely for the production of gaseous and liquid final products, while the waste molten slag has a rather high content of iron oxides (up to 24%) and silicon oxides (up to 40 %).

A well-known energy-technology installation containing a lined gasifier for producing synthesis gas with a plasma torch installed in its lower part and a low-grade solid fuel dispenser in the upper part and hot synthesis gas discharge pipes and slag pipes (A. G. Artamonov. Processing of various organic waste in a plasma-chemical reactor, in the book Apparatuses for High-Temperature Technology - M: Moscow Institute chemical engineering, Interuniversity collection of scientific papers. 1988, p. 63-64).

This unit is designed exclusively for gas production, while solid metal is used almost completely, and the waste is ash and slag. The design of this installation does not provide sufficient flexibility of the technological process in relation to the production of other products.

The closest in technical essence and the achieved result (prototype) is a combined-cycle gas and 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 waste heat boiler, a combustion chamber, a gas battery, gas purification system, air and gas compressors and a catalytic reactor for producing liquefied hydrocarbons, characterized in that one of the steam generators is installed inside a plasma-thermal gasifier having at least two plasma torches on water vapor and is hydraulically connected to a steam turbine, a coal supply unit and one of the plasma torches, the second steam generator is installed inside the recovery boiler under a gas burner for burning synthesis gas and is hydraulically connected to the second steam a turbine, a coal supply unit and another plasmatron, while both steam generators are hydraulically connected to the heat recovery circuit, and the gas turbine outlet is located inside the recovery boiler in the flame zone neither its gas burner and is hydraulically connected through the heat exchanger of the steam generator and the smoke exhauster to the chimney, while the synthesis gas purification system is divided into two stages connected to the plasma-thermal gasifier by means of a steam ejector and to each other by gas blowing, of which the first stage is wet and includes a centrifugal sparger with a recirculating liquid absorbent circuit and a device for removing slag, and the second stage is dry and includes a replaceable catalyst block with electrostatic precipitators and a device for 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 located after the second stage of the synthesis gas purification, and the gas processor is installed in the synthesis gas supply line of the catalytic reactor high pressure and a device is provided for sampling gaseous and liquefied gasification products, for example synthesis gas and gasoline (Russian Patent N ° 2105040, application. March 29, 95. Publish. Bull. JN5, 1998). A disadvantage of the known installation is the incomplete use of its working volume, the limited scope of its application is the impossibility of its use in metallurgy. The slag formed during gasification is at a gasification temperature in a liquid state, and when slag enters the lower part of the gasifier, where the temperature is much lower than the gasification temperature, liquid slag hardens and forms a deposit at the bottom of the gasifier, which shortens its life. In addition, the placement of steam generators inside the plasma-thermal gasifier and the recovery boiler, if necessary, carry out repair work on them leads to a stop of the installation as a whole. The installation provides for mandatory preliminary preparation of the initial fuel, which also reduces its effectiveness.

The first of the group of inventions is based on the task of improving the method of plasma-thermal processing of fossil fuels by creating a cycle of non-stop processing of any carbon-containing raw materials, any fractional composition, without its preliminary preparation and maximum use of the reaction space of gasifiers, which ensures synthesis gas production, its use for generating electricity, ferrosilicon and fillers while maintaining a clean environment and reducing energy.

The second of the group of inventions is based on the task of improving the installation for plasma-thermal processing of organic fuel by creating a cycle of non-stop and non-waste processing of feedstock by sequentially placing the corresponding apparatuses during the process and complete processing of the feedstock in a single technological unit while maintaining a clean environment.

The first task is solved by the fact that in the method of plasma-thermal processing of organic fuel, in which the gasification of organic fuel is carried out simultaneously with the process of high-temperature pyrolysis in the presence of a reagent that is injected into the reaction zone using plasma sources, cooling and purification of impurities obtained synthesis gas, according to the invention, the gasification of the feedstock in each gasifier is carried out alternately in the plasma stream so 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 carried out in the second gasifier, while the cycles are repeated until the height is reached liquid slag in one of the gasifiers, which is determined by the dependence:

where Δ is the height of the liquid slag;

Gn is the plasma gas flow rate, kg / s; Pn — plasma density, kg / m ³ ;

P _R A _SP - melt density, kg / m; dс is the diameter of the output nozzle of the plasma torch, m; g is the acceleration of gravity, m / s ² ; π = 3.14, then the liquid slag is purged with a reducing plasma jet and, after the metal and slag are drained in one gasifier, reload it with feedstock and the cycle is repeated, while water is used as one of the plasma-forming components.

The claimed method of processing solid fuel allows in one technological unit to carry out oxidation processes in a cyclically sequential mode by treating raw materials, such as coal, with an oxidizing plasma jet to produce synthesis gas for subsequent generation of electricity and metal recovery from unreacted solid residue (slag) by periodic slag purging with a reducing plasma jet in order to obtain valuable components, while one of the plasma-forming their components is water.

The analytical dependence given above relates the operation mode of the plasma torch in the slag melt to the gas-dynamic parameters of the molten liquid bath. If this ratio is not fulfilled, then the gas-dynamic locking of the plasma torch occurs or the melt splashes out of the slag collector and accumulates on the walls of the oxidizer zone of the gasifier, forming arches, bridges and accretions, as a result of which the process stops. Substitution of a portion of a reagent including a gaseous oxidizing agent, such as air or steam to water, can improve the efficiency of the process and reduce the amount of harmful NO ₂ emissions. Since oxygen and hydrogen are formed during the plasma conversion of water, free oxygen is consumed for fuel oxidation, and hydrogen is used as an additional fuel cell, which increases the energy content of synthesis gas and maintains a clean environment.

Another task is solved by the fact that in the installation for plasma-thermal processing of organic fuel, which includes a lined gasifier connected in the upper part with fuel supply units, plasmatrons, a combustion chamber, a slag collector located in the lower part of the gasifier, a synthesis gas purification system associated with gasifiers, 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 and a receiver - a cyclone connected and between themselves in the upper part by a pipeline for transporting synthesis gas, the receiver-cyclone in the lower part is connected by dust conduits to gasifiers, and the plasma torches are installed on both sides of the plane of the partition wall of the gasifier and slag collector, respectively, in the wall of each gasifier and slag collector, opposite in slag collectors there are slots for pouring metal ligatures into molds and depleted slag melt into a granulator, and the receiver - a cyclone with a synthesis gas supply pipe, connect It is connected with a gas-cooled heat exchanger, one pipe of which is connected to a steam turbine, and the second through a hot-cleaning system and a ceramic filter, connected to a combustion chamber of a gas turbine connected to a recovery boiler, and the additional output of the ceramic filter is connected through a synthesis gas, an additional purification unit and a compression unit for synthesis gas with plasmatrons.

The layout solution of units and assemblies and their placement during the technological process, ensured the creation of a waste-free integrated processing of raw materials in a single technological unit while maintaining a clean environment.

The installation is structurally composed of two units - a gasification unit and an energy conversion unit. The gasification unit consists of paired, lined with refractory bricks, gasifiers and a cyclone receiver located in a sealed metal case. The cyclone receiver provides equalization of the pressure of the synthesis gas in the system and at the same time serves as the first step in cleaning the synthesis gas from dust. Placing oxidizing plasmatrons in the lower part of gasifiers allows efficient processing of fuel in countercurrent mode. Plasmatrons installed in slag collectors provide operation in both oxidizing and reducing conditions, which makes it possible to use them additionally for gasification of fuel when the gasifier is switched on in the oxidation mode with a flexible and mobile control system capable of providing a quick transition from one operating mode to other.

The energy conversion unit includes a synthesis gas cooling and purification system, a gas turbine and steam turbine installation with electric generators and a steam regeneration system, and a flue gas cleaning and removal system. The scheme for generating electricity and synthesis gas is quite flexible and simple. The invention is illustrated by the drawing, which shows a diagram of a plant for plasma thermal processing of fossil fuels. The claimed method is implemented as follows. Carbon-containing raw materials are purged with plasma oxidizing jets in the volume of the first gasifier. As a result of gasification, synthesis gas is obtained, which is sent for subsequent use in the production of electricity, and the resulting liquid slag is accumulated in the slag collector until it reaches a predetermined height, which is determined by the dependence:

where Δ is the height of the liquid slag;

Gn is the plasma gas flow rate, kg / s; rp - plasma density, kg / m;

P _R A _SP - melt density, kg / m ³ ; dс is the diameter of the output nozzle of the plasma torch, m; g is the acceleration of gravity, m / s ² ; π = 3.14, after which the liquid slag is purged with a reducing plasma and at the same time carry out a cycle of oxidation of carbon-containing raw materials in the second gasifier and, after draining the metal and slag from the first gasifier, load it with feedstock and repeat the cycle. Depending on the brand of coal, its ash content, gasifier operation cycles in the oxidative mode of synthesis gas production can be repeated two to four times until liquid slag reaches the calculated height in one of the gasifiers.

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 liquid slag as it accumulates. Installation for the processing of fossil fuels contains gasifiers 1 and

2, combined by a high-temperature receiver-cyclone 3, and equipped with loading devices 4 in the upper part and plasmatrons 5 located opposite each other in the lower side part. The lower part of the gasifiers 1, 2 is connected to slag collectors 6 of liquid slag, in which side plasmatrons are installed 7. Slots 8 are filled with slots 8 for pouring metal ligatures into molds 9, and depleted slag melt into granulators 10. Plasmatrons 5 and 7 are connected to power sources 11 that provide the necessary energy physical characteristics of the arc discharge to a compressor 12 supplying a plasma to the centrifugal air pump 13 supplying the cooling water and the plasma-forming. The energy conversion unit includes a cooling and fine purification system for the produced synthesis gas, comprising a heat exchanger 14 connected at the outlet of the cyclone receiver 3, connected to a steam turbine 15, and then sequentially to a hot cleaning system 16, a ceramic filter 17, a combustion chamber 18 gas turbine 19. On the axis of the gas turbine 19 is an electric generator 20 and a compressor 21 for supplying gas to the combustion chamber 18. The gas turbine 19 is connected to a waste heat boiler 22. For operation of the plasma torches in a recovery mode This is used a block consisting of successively interconnected node 23 ADF syngas intensive cooling assembly 24, assembly 25 and purification unit compressing syngas 26 connected to the plasma torches 7. The device operates as follows. Coal raw materials loading device 4 is loaded from above into the first gasifier 1. Plasma-forming air is supplied to the plasma torches 5 and 7 by a plasma-forming air 12, and a plasma-forming and cooling water is supplied by a centrifugal pump 13. Using a power source 11, arc discharges are excited and plasmatrons 5 and 7 are triggered. Plasma oxidizing jets blow a layer of feedstock generated during gasification of the synthesis gas through a line equipped with non-return valves, enters the high-temperature receiver-cyclone 3, in the lower part of which the dust removal system for gasifiers 1, 2. The cyclone receiver 3 is designed to equalize the pressure of the synthesis gas in the system and at the same time serves as the first step in cleaning the synthesis gas from dust. At this time, the charging device 4, the feedstock is loaded into the gasifier 2. After the gasification process in the first gasifier is completed, the plasma torches 5 and 7 are turned off and turned on in the gasifier 2. Then the process is repeated.

Heated to a temperature of 1100-1300 ⁰ C synthesis gas from a high-temperature receiver-cyclone 3 at an excess pressure of 1-5 atm enters the gas-cooling heat exchanger 14, where it is cooled to a temperature of -540 ⁰ C. From the heat exchanger 14, the steam enters the steam turbine 15 for power generation.

The synthesis gas cooled in the heat exchanger 14 to a temperature of ~ 540 C enters the hot desulfurization system 16, where sulfur in the fluidized bed is adsorbed by zinc titanate, which is partially withdrawn for regeneration. After hot desulfurization in the candles of the ceramic filter 17, volatile dust is removed from the synthesis gas and then the gas enters the combustion chamber 18 of the gas turbine 19. On the axis of the gas turbine 19 there is an electric generator 20 and a compressor 21 supplying air to the combustion chamber 18. After the gas turbine 19, the combustion products are sent to a waste heat boiler 22 and then removed into the chimney. The steam obtained in the recovery boiler 22 is supplied to a steam turbine 15 to generate electricity. Electricity produced in gas and steam turbines is partially used for own needs (operation of plasmatrons, pumps, a compressor, etc.) and is delivered to the consumer’s network.

Depending on the brand of coal, its ash content, the cycles of gasifiers 1 and 2 in the oxidative mode of synthesis gas production can be repeated 2-4 times until liquid slag reaches a thickness Δ in one of the gasifiers. At reaching the slag level of a given thickness, the plasma torches 7 placed in the slag collector of the gasifier are transferred to the recovery 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 unit 23 to the intensive cooling unit 24, then to the additional cleaning unit 25 and the compression unit 26, from which it is purified, cooled to a temperature of ~ 30 ⁰ C and compressed to a pressure of 3-6 atm synthesis gas is supplied to the plasma torches 7. Under the action of reducing plasma jets, iron and silicon are reduced from slag. The resulting metal ligature - ferrosilicon through a tap hole 8 is poured into the mold 9, and depleted liquid slag into the granulator 10. The time of the metal recovery process does not exceed 20-40 minutes and therefore fits into the gasification process cycle. After the discharge of metal and slag from the slag collector, a fresh portion of coal is loaded into the gasifier and the plasmotrons 5 of the gasifier and the plasmatrons 7 of the slag collector begin to work in the oxidizing mode. After the gasification process in this gasifier is completed, the plasma torches in the second gasifier are turned on, and then the process is repeated.

The performed calculations and experimental results show that with plasma-thermal gasification of coal, atmospheric emissions are ten times less than with any other processes based on coal combustion. This is due to the fact that in plasma gasification, in contrast to the well-known combustion processes occurring at a 5-6-fold ratio of air to coal, the amount of oxidizing agent is set strictly dosed and only to maintain the reaction of incomplete carbon oxidation. So, with a weight ratio of air / water not exceeding 0.3, the concentration of nitrogen in the oxidizing plasma does not exceed 20% and therefore the yield of nitrogen and nitrogen compounds in the final product does not exceed 10%, with almost no CO ₂ and H ₂ O.

It was experimentally established that when the power of the inventive installation is up to 0.7 MW and the power of three simultaneously operating plasmatrons is up to 0.6 MW when processing 1000 kg / h of grade G coal, an output of 1000 kg / h of synthesis gas heated to 1000 ⁰ C is provided, and the network is delivered 1500 kW-hours of electricity, production of up to 40 kg / h of ferrosilicon and up to 150 kg / h of lightweight filler for reinforced concrete and other structures.

The claimed method of thermal processing of fossil fuels and a combined-cycle plant for its implementation allow to efficiently process the source carbon-containing raw materials of any fractional composition with maximum extraction of high-quality finished products with minimal impact on the environment.

Claims

Claim

1. The method of plasma-thermal processing of organic fuel, including the gasification of organic fuel simultaneously with the process of high-temperature pyrolysis in the presence of a reagent that is injected into the reaction zone using plasma sources, cooling and purification of impurities of the obtained synthesis gas, characterized in that the gasification of the feedstock in each the gasifier is produced alternately in the plasma stream so that after the end of the oxidation regime in the first gasifier, the plasma Ie, and the oxidation mode is produced in the second gasifier, while the cycles are repeated until the height of liquid slag in one of the gasifiers is reached, which is determined by the dependence:

where Δ is the height of the liquid slag;

Gn is the plasma gas flow rate, kg / s; Pn — plasma density, kg / m ³ ;

P _R A _SP - melt density, kg / m ³ ; dс is the diameter of the output nozzle of the plasma torch, m; g is the gravitational acceleration, m / s ² , π = 3.14, then the liquid slag is purged with a reducing plasma jet and, after the metal and slag are drained in one gasifier, re-charged with feedstock and the cycle is repeated, with One of the plasma forming components uses water.

2. Installation for plasma-thermal processing of organic fuel, containing a lined gasifier connected in the upper part with fuel supply units, plasmatrons, a combustion chamber, a slag collector located in the lower part of the gasifier, a synthesis gas purification system associated with gasifiers, a heat exchanger, gas and steam turbines with electric generators, a waste heat boiler, characterized in that the installation is equipped with an additional gasifier and a cyclone receiver connected between each other in the upper part by a pipeline for transporting synthesis gas, the receiver cyclone in the lower part is connected by dust conduits to gasifiers, and the plasma torches are installed on both sides of the plane of the partition wall of the gasifier and slag collector, respectively, in the wall of each gasifier and slag collector, opposite slag compartments are made with slots for pouring metal ligatures into molds and depleted slag melt into a granulator, and the cyclone receiver, connected to the synthesis gas supply pipe, is connected to an azo-cooling heat exchanger, one pipe of which is connected to a steam turbine, and the second through a hot cleaning system and a ceramic filter, is connected to a combustion chamber of a gas turbine connected to a recovery boiler, while the additional output of the ceramic filter is connected through an automatic synthesis gas supply unit, an additional purification unit and a synthesis gas compression unit with plasmatrons.