RU2521638C2 - Gasification of carbon-bearing solid fuels - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to gasification of solid carbon-bearing combustibles, i.e. lignite and coal, shale oil and peat. Gasification comprises heating and pyrolysis of solid carbon fuel fed into bath with fused melt of sealed electrode kiln at forcing gasifying agents through fused slag with solid carbon fuel. Besides, electric current is passed by electric circuit including electrodes fed into kiln bath and kiln hearth. Synthesis gas, slag and metal alloy is removed from kiln working space. Three-phase current if fed through fused slag with solid carbon fuel, current magnitude being defined in compliance with solid fuel consumption and required power defined by relationship: $$P_a=\frac{G\times w_p}{3600},MW,$$

where G is solid fuel consumption, kg/h, w_p is specific power consumption.

EFFECT: more efficient application of electric power, more stable process.

1 dwg, 1 tbl

Description

The invention relates to methods for gasification of solid types of carbon fuel: brown and black coal, shale and peat. The invention can be used in energy, chemical and metallurgical industries.

The use of direct methods of burning solid fuels for gasification has low efficiency due to incomplete combustion of fuel and low efficiency of furnaces, high cost of transportation and environmental pollution. Solid fuels cannot fundamentally be used in the most modern technologies of energy generation (gas turbine plants, combined-cycle plants, gas piston units) without first converting solid fuel into a gaseous or liquid state. The use of solid fuels in traditional generation in the steam cycle has unsatisfactory energy efficiency, as well as harmful atmospheric emissions of sulfur oxides, ash particles and dumps containing heavy metals. One of the priority areas for the technical re-equipment of thermal power plants is the introduction of highly efficient environmentally friendly technologies for the production of electric and thermal energy using gasification of solid fuel (Dyakov A.F. et al. New approaches to the technology of using solid fuel in the electric power industry. - "Power Engineering", 1998, N 2).

Chemical reactions of thermochemical processing of solid fuels in gas generators proceed with the release and absorption of heat, MJ / kmol (High-temperature heat-engineering processes and plants. / I.I. Pereletov, L.A. Brovkin, I.Yu. Rozengart et al., Ed. A . D. Klyuchnikova. - M.: Energoatomizdat, 1989.336 s.)

$$C+O_2=C{O}_2+407;\left(\mathrm{one}\right)$$

$$C+0.5O_2=CO+123;\left(2\right)$$

$$C+H_{2}O=CO+H_2-118.7;\left(3\right)$$

$$C+2H_{2}O=C{O}_2+2H_2-75.5;\left(\mathrm{four}\right)$$

$$C+C{O}_2=2CO-161.5;\left(5\right)$$

$$CO+0.5O_2=C{O}_2+284;\left(6\right)$$

$$C{O}_2+H_2=CO+H_{2}O-43.6;\left(7\right)$$

In autothermal gas generators, the thermal energy necessary for gasification processes is obtained by oxidizing part of the solid fuel.

A known method of gasification of solid fuel in a slag melt sparged with oxygen blast (patent RU 2181861, IPC F23C 3/00. The method of step-by-step gasification and burning of solid fuel in aero-slag melt. Madoyan AA; Efimov NN, Sverdlov V.I. , published on April 27, 2002).

The method includes burning solid fuel in a bath with a liquid melt of slag when a gasifying agent is supplied to it under pressure with the formation and removal of gas from the bath, as well as mineral components from the liquid phase of the melt. In this case, the bath is filled with liquid slag, solid fuel, for example coal, is loaded, and a gasifying agent (oxygen or water vapor) is supplied. Fuel, falling into the volume of liquid slag, is heated, its pieces crack and melt. In the chamber, the process of intensive gasification of fuel in the melt volume begins under the influence of a gasifying agent. When using oxygen as a gasification agent, gasification occurs in accordance with reaction (2), water vapor in accordance with reaction (3) and (4)). Gasification agents and gases released by reactions (2,3,4) sparge molten slag. At the same time, boiling slag plays the role of a heat carrier, which provides ideal conditions for heat and mass transfer of all components of the melt, including fuel with an oxidizing agent. In this case, the fuel-slag mixture heats up, thermal crushing and melting of all its components occurs, except for carbon, which behaves as an unwettable substance. As a result, “non-wettable light carbon” rises to the upper part of the melt, fuel carbon is demineralized by separating (melting) the mineral components in the liquid phase of the melt with the formation of non-wettable carbon of high concentration.

The resulting synthesis gas is sent to the exhaust pipe. Light slag accumulates in the upper part of the melt, which is a valuable raw material for building products, and in the lower part, a liquid metal phase of industrial importance is concentrated.

The technology of coal gasification in slag melt sparged with oxygen blast has the following main advantages:

- the ability to use any low-grade and non-projective coals regardless of their brand and quality;

- the possibility of the beneficial use of the mineral part of the fuel with the recovery and removal of ferrous and non-ferrous metals from the melt;

- high environmental cleanliness of the processes (emissions of particulate matter - not more than 50 μg / m ³ , nitrogen oxides - not more than 100 mg / m ³ , a 30% reduction in SO ₂ emissions and 10% CO ₂ emissions;

- lack of bulky fuel preparation systems, dust supply and ash treatment, lack of ash dump.

The disadvantage is that with autothermal technologies, which is the method of gasification of solid fuel according to patent No. 2181861, up to 40% of the fuel is spent on maintaining the process temperature. Moreover, when using fuels with a high content of mineral component (coal and slate) and low calorific value of the fuel used, the temperature of the slag melt is not enough to provide a high-performance gasification process, and it is impossible to produce gas whose energy value would exceed 70% of the energy value of the fuel used . In this case, the slurry fluidity in this process is not sufficient to remove the mineral part of the fuel from the bath.

In addition, the disadvantages of technology based on autothermal smelting in a liquid bath are also:

limited sustainable technological regimes of the autogenous process;

the difficulty of starting and stopping the installation.

Save all the advantages of gasification in slag melt and get rid of the shortcomings of the autothermal process of melting in a liquid bath allow based on the conversion of electrical energy into heat. Electrotechnological processes carried out in electrode furnaces allow gasification of any type of solid fuel with the full use of raw materials to produce high-calorie gas, metal alloy and building materials from slag. Gasification in electrotechnological installations allows obtaining synthesis gas with a high content of hydrogen and carbon monoxide from various types of solid fuel, which can be used as fuel in any installations, as well as as a raw material in the chemical industry.

The closest technical solution to the claimed invention is a method of gasification of carbon-containing solid fuels (SU No. 878774 A1, C10J 3/18, publ. 07.11.1981). This method involves heating, pyrolysis of solid carbon fuel supplied to a bath with molten slag of an electrode electric furnace while passing a gasifying agent through the slag melt, using a mixture of water vapor and oxygen in the following ratio of components to carbon mass of coal, wt.%:

Water vapor 15-45 Oxygen 55-85

and electric current.

To do this, solid fuel, gasifying agents (oxygen and water vapor), and mineral additives are supplied to the electrotechnological installation. In the working space of the installation is the conversion of electrical energy into energy. The processes of heating, drying, pyrolysis, semi-coking and gasification of the coke residue with oxygen and water vapor, the reduction of oxides of the mineral part of the feedstock with carbon, as well as the formation of slag and metal melt, the process of gasification of solid fuel.

The disadvantage of this method is that when it is implemented, electric energy cannot be used effectively enough, since the parameters and the amount of current required to carry out and maintain the process are not set, and the process itself cannot be carried out stably.

The technical result of the claimed invention is to increase the efficiency of use of electric energy in the implementation of the method and to increase the stability of the process.

This technical result is achieved by the fact that during the gasification of solid types of carbon fuel, including heating, pyrolysis of the sealed electrode furnace of carbon fuel supplied to the bath with molten slag when passing gasification agents through the slag melt, as well as passing electric current, removes synthesis from the working space of the furnace gas, slag and metal alloy, in accordance with the invention, a three-phase electric current is passed through the slag melt, the value of which is determined I in accordance with the consumption of solid fuel and taking into account the necessary power, determined from the expression

Where

G - solid fuel consumption in an electric furnace, kg / h,

w _el - specific consumption of necessary electricity, determined by physical and mathematical modeling, equal to:

- for gasification of coal and use in the gasification process as a gasifying agent, a vapor-oxygen mixture of 2.20-2.356 MJ / kg, water vapor 7.0-7.23 MJ / kg, oxygen 0.20-0.23 MJ / kg;

- for the gasification of brown coal and peat and use in the gasification process as a gasifying agent, an oxygen-vapor mixture of 2.50-2.83 MJ / kg, water vapor 5.0-5.08 MJ / kg, oxygen 0.08-0.1 MJ / kg;

3600 - conversion factor kg / h to kg / s,

based on which determine the power per one electrode:

where 10 ⁶ is the power conversion factor in watts, η is the electrical efficiency,

m is the number of electrodes equal to 3,

then determine the amount of current per one electrode:

where C is the technological parameter, which is a complex characteristic of the electrotechnological regime of the installation of electrothermal gasification of solid fuels, the values of parameter C determined by physical and mathematical modeling are 0.88 V / W ^1/3 for gasification of coal and 0.85 V / for peat gasification Tue ^1/3 .

The method is as follows. First, a layer of molten slag is created in the bath of the electrothermal gasifier. When the working mass of fuel enters the electrothermal gasifier, the materials are heated, moisture evaporates and volatiles are released from the organic mass of solid fuel. The high temperature and the presence of a gasification agent in the reaction zone contribute to the most complete gasification of carbon, which is part of the combustible mass, with the formation of a mixture of carbon monoxide and hydrogen. The iron and silicon oxides contained in the ash are reduced by carbon by reactions.

$$F{e}_m{O}_n+nC=mFe+nCO\left(8\right)$$

$$Si{O}_2+2C=Si+2CO\left(9\right)$$

Figure 1 shows a schematic drawing of electrothermal gasification of solid fuel. In the bath of the installation there are solid fuel 2, molten slag 3, metal alloy 4. Using electrodes 1, an alternating three-phase electric current is supplied, which flows through the molten slag, and the electromagnetic field energy is converted into thermal energy. To create a symmetrical load on the power grid, three-phase alternating current is used, 3 electrodes are installed in the furnace melt. An electric circuit is created in the electric furnace, including graphite electrodes immersed in the melt, slag and metal alloy layers on the bottom of the electric furnace.

Based on the size of the bath, the consumption of solid fuel is determined, that is, the amount of the loaded amount of fuel per unit time. When it is heated to 100-110 ° C in the heating zone, it is dried. In the temperature range of 100-250 ° C, thermal decomposition begins with the release of pyrogenic water, dioxide and carbon monoxide, at a higher temperature, hydrocarbons, tar vapors and other organic compounds begin to be released. The bulk of the volatiles is released from young fuels at 270-450 ° C, and from old ones at 350-500 ° C, the release of resin ceases at 500-580 ° C. When heated to 500-700 ° C, semi-coking of solid fuel occurs. At a higher temperature in the reaction (slag) zone, gasification of the coke residue and melting of the mineral part of the fuel begin. The thermal energy necessary to maintain endothermic processes is obtained when electric current spreads over the materials of the reaction zone. To do this, an electric current is passed through the molten slag with carbon solid fuel using electrodes, the value of which is determined in accordance with the consumption of solid fuel, taking into account the required power, determined from the expression

, где $$P_a=\frac{G\cdot w_{\mathrm{uh}l}}{3600},M\mathrm{AT}t$$

where

G - solid fuel consumption in an electric furnace, kg / h,

w _el - specific energy consumption, determined by physical and mathematical modeling, equal to:

- for gasification of coal and use in the process of gasification as a gasifying agent, an oxygen-vapor mixture - 2.20 ... 2.356 MJ / kg;

- during the gasification of brown coal and peat and the use of a vapor-oxygen mixture as a gasifying agent in the gasification process - 2.50 ... 2.83 MJ / kg;

- for gasification of coal and use in the process of gasification as a gasifying agent, steam - 7.0 ... 7.23 MJ / kg;

- for the gasification of brown coal and peat and the use of steam 5.0 ... 5.08 MJ / kg in the gasification process as a gasification agent;

- for gasification of coal and use in the gasification process as oxygen gasification agent - 0.20 ... 0.23 MJ / kg;

- for gasification of brown coal and peat and use in the gasification process as an oxygenating agent of oxygen 0.08 ... 0.1 MJ / kg,

m is the number of electrodes equal to 3;

3600 - conversion factor kg / h to kg / s (kg / s * MJ / kg = MJ / s = MW)

10 ⁶ - power conversion factor in watts.

Then determine the power per one electrode, W

$$P_{\mathrm{uh}a}=\frac{{10}^6\cdot R_{\mathrm{but}}{\eta }_{\mathrm{uh}l}}{m}$$

where m = 3 is the number of electrodes, η _el is the electrical efficiency,

then determine the amount of current per one electrode

$$I=\frac{p_{\mathrm{uh}\mathrm{but}}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{\mathrm{FROM}}$$

where C is the technological parameter, which is a complex characteristic of the electrotechnological regime of the furnace installation (Electrothermal processes of chemical technology. / Ed. by V.A. Ershov. - L .: Chemistry, 1984, 464 p.). So for installations of electrothermal gasification of solid fuel, the parameter values determined by physical and mathematical modeling for gasification of coal are C = 0.88 V / W ^1/3 , for gasification of brown coal and peat 0.85 V / W ^1/3 .

Complete gasification of the coke residue occurs at temperatures above 1200 ° C. The mineral part of the fuel and mineral additives form a slag melt. Oxides of iron, silicon and other elements are reduced by carbon, and a metal alloy is formed.

Thus, electrothermal gasification plants are high-temperature chemical reactors with a complex structure of the working zone and an uneven distribution of heat and temperature sources. In the upper levels, where the cold charge enters, all the components are solid; as the mixture goes down, the temperature rises and a liquid phase appears. The region of maximum temperatures is located near the working ends of the electrodes, since most of the power is released there due to the spreading of current through the bath materials. In this area, endothermic reactions occur intensively. Since lumps of solid fuel and molten slag have a certain electrical conductivity, heat is generated during electric current spreading over them, therefore, an electrothermal electrode gasifier can operate in resistive heating mode, when heat is released when current spreads over bath materials.

In view of the possibility of maintaining a sufficiently high and stable temperature in the gasification zone, electrothermal gasification allows you to convert the entire combustible mass of low-grade solid fuel into high-calorific synthesis gas practically free of nitrogen, carbon dioxide and water vapor.

Physical and mathematical modeling of the process for determining w _el was carried out taking into account the full energy balance of the electrothermal gasification process, which includes the consumption and arrival of thermal energy.

Moreover, in the physical and mathematical modeling of the process, we proceeded from the fact that the energy balance should take into account the energy consumption for:

moisture evaporation q _ow ,

heating the dry mass to the temperature of the onset of pyrolysis q _c ,

heating to a temperature char gasification q _to start,

endothermic gasification of carbon semicoke with water vapor q _end ,

the melting of slag-forming materials and the mineral part of the fuel q _s ,

reduction of oxides of the mineral part of the ash fuel q _vos ,

heat loss q _sweat;

electric losses q _el

and the energy supply in the electrothermal gasifier includes

active electricity converted into heat w _el

exothermic chemical reactions of gasification of carbon of semicoke with oxygen q _ex ,

physical heat of materials supplied to the working area of the installation q _W

The energy balance of an electrotechnological installation during allothermic gasification

q _ow + q _s + q _to + q _end + q _s + q _vos + q _sweat + q _el = w _el + q _ind + q _w

The specific energy consumption required for the gasification process is

W _e = q + q _{is from to} + q + q + q _{End of Sun} + q + q + q _{sweat e} -q _specimens -q _w

At the same time, the specific energy consumption depends on the gasification technology and the type of fuel (coal, brown coal, peat). When using water vapor as a gasification agent, oxygen is not used. It was empirically determined that the specific energy consumption w _el for steam gasification of coal is 7.0 ... 7.23 MJ / kg, for steam gasification of brown coal and peat 5.0 ... 5.08 MJ / kg. It was revealed that in this case, the synthesis gas obtained in accordance with the claimed method contains up to 56% hydrogen, therefore, it can be used not only as fuel, but also as a raw material for the chemical industry.

When only steam is used as a gasification agent by the endothermic reaction (3), the supply of thermal energy is necessary, and the electric power consumption will be maximum. When only oxygen is used as the gasification agent in the exothermic reaction (2), the heat generated almost completely compensates for the energy costs of all processes during gasification, while the energy consumption will be relatively small. When using a vapor-oxygen mixture as a gasification agent, a thermoneutral gas production mode is possible in which the thermal effects of the endothermic reaction (3) and exothermic reaction (2) are equal in magnitude. When using a mixture of oxygen and water vapor as gasifying agents, the optimal oxygen content in the mixture is 55% (High-temperature heat-technological processes and installations. / I.I. Pereletov, L.A. Brovkin, I.Yu. Rozengart et al. / Ed. A.D.Klyuchnikova. - M.: Energoatomizdat, 1989.336 s.).

When using a vapor-oxygen mixture as a gasification agent and receiving thermoneutral gas during gasification, electricity is consumed only for moisture evaporation, heating of materials and ash melting, the energy consumption will be significantly less than with gasification only with steam.

It is empirically determined that, for coal, the specific energy consumption is 2.356 MJ / kg, when using a vapor-oxygen mixture as a gasification agent; for the gasification of brown coal and peat, the specific energy consumption is 2.83 MJ / kg, and the synthesis gas obtained in accordance with the claimed method contains up to 45% hydrogen.

The energy potential of the generator gas Qg, which is defined as the product of the net calorific value of gas and the specific gas output

, $$Qg=Q_n^R{v}_g$$

,

-рабочая низшая теплота сгорания генераторного газа, v_г - удельный выход газа.Where $$Q_n^R$$

-operating net calorific value of the generator gas, v _g - specific gas output.

The energy potential of steam gasification obtained from 1 kg of coal synthesis gas will be 29.65 MJ, out of 1 kg of brown coal 17.36 MJ.

The energy potential of synthesis gas obtained from 1 kg of coal will be 24.345 MJ, out of 1 kg of brown coal 14.63 MJ.

When using oxygen as a gasification agent during gasification of coal, it was empirically determined that the specific energy consumption is 0.20 ... 0.23 MJ / kg, while the oxygen gasification of brown coal and peat, the specific energy consumption is 0.08 ... 0.1 MJ / kg It was determined that the resulting synthesis gas contains up to 71% carbon monoxide.

The energy potential of synthesis gas obtained from 1 kg of coal will be 18.88 MJ, out of 1 kg of brown coal 11.8 MJ.

When water vapor is used as a gasification agent during gasification of brown coal and peat, gasification occurs by the endothermic reaction (3) only at the expense of electricity; energy costs for gasification of 1 kg of brown coal and peat are 5.598 MJ.

The table below shows the gasification of coal in accordance with known methods without passing electric current through electroslag melt and in accordance with the claimed method.

Table Gasification Method A.S. 1333686 Autothermal gasification Patent 2422538, Autothermal Gasification claimed, vapor-oxygen allothermic gasification claimed, oxygen allothermic gasification claimed, steam allothermic gasification Consumption Coal, t / h 19.77 24,332 14.8 19,976 2,368 Oxygen, thousand m ³ / h 16,475 14,434 5.25 14,443 -

Steam, t / h 0.44 - 6.12 - 10,067 Power, MW - - 9,686 1,276 24.84 The value of the transmitted current, kA - - 23.49 6.08 47.0 Exit Synthesis gas, thousand m ³ / h 35.15 37,116 32.28 32.28 32.38 The content in the synthesis gas of carbon monoxide and hydrogen,% vol 90 79 98 98 98 Net calorific value of synthesis gas, MJ / m ³ 10,242 9.7 11,152 11,152 11,152 The energy potential of the synthesis gas obtained during the hour, GJ 360 360 360 360 360

From the table it follows that during electrothermal gasification, solid fuel and oxygen are used more efficiently, synthesis gas has a higher content of carbon monoxide and hydrogen and a higher calorific value.

Example 1. Gasification of coal is carried out when fed into a bath with a slag melt of water vapor and oxygen.

An oxide melt bath of the following sizes was used: diameter 4.5 m, depth 1.25 m. The melt density in the bath is 2.65 g / cm ³ . The volume of the melt bath is 19 m ³ , the mass of the melt is 52 tons. The process was carried out at a bath temperature of 1450 ° C. Coal in the form of pieces of size 20 ... 30 mm in the amount of 14800 kg / h is fed into the bath through the loading devices. When pieces of coal get on the surface of the melt, the pyrolysis of coal occurs with the formation of coke, which floats in the melt. In the working space of the bath, a suspension is formed, into which water vapor is supplied in an amount of 6120 kg / h and oxygen in an amount of 5250 m ³ / h.

Empirically established using physical and mathematical methods, the specific energy consumption for coal equal to w _el = 2,356 MJ / kg

For installations of electrothermal gasification of solid fuels, the values of the technological parameter determined by physical and mathematical modeling are C = 0.88 V / W ^1/3 .

Simultaneously with the supply of coal, an electric three-phase current is passed through the melt. The magnitude of the transmitted current is selected as follows. Based on the consumption of solid fuel G = 14800 kg / h, we determined the active power of the installation

$$P_a=\frac{G\cdot w_{\mathrm{uh}l}}{3600},M\mathrm{AT}t$$

$$P_a=\frac{14800\cdot \mathrm{2,356}}{3600}=\mathrm{9,686}M\mathrm{AT}t$$

Power coming to one electrode, W

$$P_{\mathrm{uh}a}=\frac{{10}^6\cdot R_{\mathrm{but}}{\eta }_{\mathrm{uh}l}}{m}$$

where m = 3 is the number of electrodes, η _el = 0.92 is the electrical efficiency. For three-electrode furnaces with a capacity of more than 9 MW, η _el = 0.92 (Short networks and electrical parameters of arc electric furnaces. Reference ed. / Ed. By Ya. B. Dancis and G.M. Zhilov. M.: Metallurgy. 1987. 320 from.)

$$P_{\mathrm{uh}a}=\frac{{10}^6\mathrm{9,686}*0.92}{3}=2970000\mathrm{AT}t$$

Electrode current

$$I=\frac{p_{\mathrm{uh}\mathrm{but}}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{\mathrm{FROM}}$$

where C = 0.88 V / W ^1/3 - technological parameter (Electrothermal processes of chemical technology. / Ed. by V.A. Ershov. - L .: Chemistry, 1984, 464 p.).

For installations of electrothermal gasification of solid fuels, the values of the technological parameter determined by physical and mathematical modeling are C = 0.88 V / W ^1/3

$$I=\frac{{2970000}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{0.88}=23490\mathrm{BUT}$$

The current is supplied through 3 graphitized electrodes. Active electric power 8.91 MW. Electrode current 23.49 kA.

Electric energy is converted into thermal energy due to the spreading of current through liquid and solid materials. Due to this thermal energy, the melt temperature is maintained at 1400 ... 1600 ° С, and the course of endothermic reactions is ensured.

In the process of coal gasification, gaseous and condensed products are formed, the mineral part of coal is melted, iron and other metals of the mineral part of the fuel are reduced, and the melt is divided into metallized and non-metallized (slag) phases.

Formed synthesis gas in an amount of 31200 nm ³ / hour, which has the following composition (% vol.): CO - 53; СО ₂ - 0.7; H ₂ - 45; H ₂ O - 0.1 ;. Gas temperature - 400 ° С, calorific value - 11540 kJ / m ³ . The energy potential of the synthesis gas is 360 GJ, the thermal capacity for the combustion of synthesis gas is 100 MW.

A slag melt is formed in an amount of 2200 kg / h with a temperature of 1450 ° C, which is discharged continuously. A metal alloy is formed in an amount of 330 kg / h with a temperature of 1550 ° C, which is periodically withdrawn once every 6 hours from the opposite side from the place of removal of slag melt.

During gasification using the technology of the prototype at a flow rate of coal of 14800 kg / h at a flow rate of oxygen of 12165 nm ³ / h, synthesis gas of 27,000 nm ³ / h will be obtained, with an energy potential of 303 GJ, the heating capacity for burning synthesis gas is 84 MW.

Example 2. The main parameters in the steam gasification of coal.

The bath of oxide melt has the following dimensions: diameter 4.5 m, depth 1.25 m. The density of the melt in the bath is 2.65 g / cm ³ . The volume of the molten bath is 19 m ³ , the mass of the melt is 52 tons. The desired bath temperature is 1450 ° C. Coal in the form of pieces 20 ... 30 mm in the amount of 12370 kg / h is fed into the bath from above through loading devices. When pieces of coal get on the surface of the melt, the pyrolysis of coal occurs with the formation of coke, which floats in the melt. In the working space of the bath, a suspension is formed, into which water vapor is supplied in an amount of 10100 kg / h.

Electric energy is introduced into the working space of the bath by passing electric current through the melt. Electric energy is converted into thermal energy due to the spreading of current through liquid and solid materials. Due to this thermal energy, the melt temperature is maintained at 1400 ... 1600 ° С, and the course of endothermic reactions is ensured.

The specific power consumption determined from the energy balance w _el = 7.23 MJ / kg and the solid fuel consumption G = 12370 kg / h determines the active power of the installation

$$P_a=\frac{G\cdot w_{\mathrm{uh}l}}{3600}$$

$$P_a=\frac{12370*7.23}{3600}=24.84M\mathrm{AT}t$$

Power coming to one electrode, W

$$P_{\mathrm{uh}a}=\frac{{10}^6\cdot R_{\mathrm{but}}{\eta }_{\mathrm{uh}l}}{m}$$

where m = 3 is the number of electrodes, η _el = 0.92 is the electrical efficiency.

$$P_{\mathrm{uh}a}=\frac{{10}^{6}24.84*0.92}{3}=7610000\mathrm{AT}t$$

Electrode current

$$I=\frac{p_{\mathrm{uh}\mathrm{but}}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{\mathrm{FROM}}$$

where C = 0.88 V / W ^1/3 - technological parameter.

For installations of electrothermal gasification of solid fuels, the values of the technological parameter determined by physical and mathematical modeling are C = 0.88 V / W ^1/3

$$I=\frac{{7610000}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{0.88}=44000\mathrm{BUT}$$

The current is supplied through 3 graphitized electrodes. Active electric bath power 24.84 MW. Electrode current 44 kA.

In the process of coal gasification, gaseous and condensed products are formed, the mineral part of coal is melted, iron and other metals of the mineral part of the fuel are reduced, and the melt is divided into metallized and non-metallized (slag) phases

Formed synthesis gas in an amount of 31200 nm ³ / hour, which has the following composition (% vol.): WITH - 42; СО ₂ - 0.7; H ₂ - 56; H ₂ O - 0.1; gas temperature - 400 ° С, calorific value - 11540 kJ / m ³ . The energy potential of the synthesis gas is 360 GJ, the thermal capacity for the combustion of synthesis gas is 100 MW.

A slag melt is formed in the amount of 1840 kg / h with a temperature of 1450 ° C, which is discharged continuously. A metal alloy is formed in an amount of 275 kg / h with a temperature of 1550 ° C, which is periodically withdrawn once every 6 hours from the opposite side from the place of removal of the slag melt.

During gasification using the technology of the prototype at a flow rate of coal of 14800 kg / h at a flow rate of oxygen of 12165 nm ³ / h, synthesis gas of 27,000 nm ³ / h will be obtained, with an energy potential of 303 GJ, the heating capacity for burning synthesis gas is 84 MW.

Example 3. The main parameters in the oxygen gasification of coal.

The bath of oxide melt has the following dimensions: diameter 4.5 m, depth 1.25 m. The density of the melt in the bath is 2.65 g / cm ³ . The volume of the molten bath is 19 m ³ , the mass of the melt is 52 tons. The desired bath temperature is 1450 ° C. Coal in the form of pieces 20 ... 30 mm in the amount of 19980 kg / h is fed into the bath from above through loading devices. When pieces of coal get on the surface of the melt, the pyrolysis of coal occurs with the formation of coke, which floats in the melt. A suspension is formed in the working space of the bath, into which oxygen is supplied in an amount of 14443 m ³ / h.

Electric energy is introduced into the working space of the bath by passing electric current through the melt. Electric energy is converted into thermal energy due to the spreading of current through liquid and solid materials. Due to this thermal energy, the melt temperature is maintained at 1400 ... 1600 ° С, and the course of endothermic reactions is ensured.

The empirically determined specific energy consumption w _el = 0.23 MJ / kg from the energy balance and the solid fuel consumption G = 19980 kg / h determines the active power of the installation

$$P_a=\frac{G\cdot w_{\mathrm{uh}l}}{3600}$$

$$P_a=\frac{19980*0.23}{3600}=\mathrm{1,276}M\mathrm{AT}t$$

Power coming to one electrode, W

$$P_{\mathrm{uh}a}=\frac{{10}^6\cdot R_{\mathrm{but}}{\eta }_{\mathrm{uh}l}}{m}$$

where m = 3 is the number of electrodes, η _el = 0.92 is the electrical efficiency.

$$P_{\mathrm{uh}a}=\frac{{10}^6\mathrm{1,276}*0.92}{3}=391000\mathrm{AT}t$$

Electrode current

$$I=\frac{p_{\mathrm{uh}\mathrm{but}}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{\mathrm{FROM}}$$

Where C = 0.88 V / W ^1/3 - technological parameter

$$I=\frac{{7610000}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{0.88}=44000\mathrm{BUT}$$

The current is supplied through 3 graphite electrodes with a diameter of 400 mm. Active electric power 1.276 MW. Electrode current 6.08 kA.

In the process of coal gasification, gaseous and condensed products are formed, the mineral part of coal is melted, iron and other metals of the mineral part of the fuel are reduced, and the melt is divided into metallized and non-metallized (slag) phases.

Formed synthesis gas in an amount of 31200 nm ³ / h, which has the following composition (% vol.): CO - 70; СО ₂ - 0.7; H ₂ - 28; H ₂ O - 0.1; gas temperature - 400 ° С, calorific value - 11540 kJ / m ³ . The energy potential of the synthesis gas is 360 GJ, the thermal capacity for the combustion of synthesis gas is 100 MW.

A slag melt is formed in an amount of 2970 kg / hr with a temperature of 1450 ° C, which is discharged continuously. A metal alloy is formed in an amount of 400 kg / h with a temperature of 1550 ° C, which is periodically withdrawn once every 6 hours from the opposite side from the place of removal of slag melt.

During gasification using the technology of the prototype at a flow rate of coal of 14800 kg / h at a flow rate of oxygen of 12165 nm ³ / h, synthesis gas of 27,000 nm ³ / h will be obtained, with an energy potential of 303 GJ, the heating capacity for burning synthesis gas is 84 MW.

Example 4

The main parameters for vapor-oxygen gasification of brown coal

. Выход летучих (%) V^daf=48.The bath of oxide melt has the following dimensions: diameter 4.5 m, depth 1.25 m. Volume 19.875 m. The density of the bath is 2.65 g / cm ³ . The melt mass is 52.7 tons. The bath temperature is 1450 ° C. Brown coal in the form of pieces of size 20..30 mm in the amount of 24610 kg / h is fed into the bath from above through loading devices. The working mass of brown coal (%): moisture W ^r = 39; ash Ar ^r = 7.3; sulfur S _op + S _k = 0.4; carbon C ^r = 37.4; hydrogen H ^r = 2.6; nitrogen N ^r = 0.6; oxygen O ^r = 12.7. Net calorific value of coal $$Q_n^p=13.02MD\mathrm{well}/\mathrm{to}g$$

. The yield of volatile (%) V ^daf = 48.

When pieces of coal get on the surface of the melt, the pyrolysis of coal occurs with the formation of coke, which floats in the melt. In the working space of the bath, a suspension is formed, into which water vapor is supplied in an amount of 5266 kg / h and oxygen in an amount of 4528 m ³ / h.

Electric energy is introduced into the working space of the bath, which is converted into thermal energy due to the spreading of current through liquid and solid materials. Due to this thermal energy, the melt temperature is maintained at 1400 .. 1600 ° С, the course of endothermic reactions is ensured.

The specific power consumption determined from the energy balance w _el = 2.83 MJ / kg and the solid fuel consumption G = 24610 kg / h determines the active power of the installation

$$P_a=\frac{G\cdot w_{\mathrm{uh}l}}{3600}$$

$$P_a=\frac{24610*\mathrm{2,38}}{3600}=19.34M\mathrm{AT}t$$

Power coming to one electrode, MW

$$P_{\mathrm{uh}a}=\frac{{10}^6\cdot R_{\mathrm{but}}{\eta }_{\mathrm{uh}l}}{m}$$

where m = 3 is the number of electrodes, η _el = 0.92 is the electrical efficiency.

$$P_{\mathrm{uh}a}=\frac{{10}^{6}19.34*0.92}{3}=5930000\mathrm{AT}t$$

Electrode current

$$I=\frac{p_{\mathrm{uh}\mathrm{but}}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{\mathrm{FROM}}$$

$$I=\frac{{5930000}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{0.85}=38560\mathrm{BUT}$$

The current is supplied through 3 graphite electrodes with a diameter of 400 mm. Active electric power 19.34 MW. Electrode current 38.56 kA.

In the process of coal gasification, gaseous and condensed products are formed, the mineral part of coal is melted, iron and other metals of the mineral part of the fuel are reduced, and the melt is divided into metallized and non-metallized (slag) phases.

Formed synthesis gas in an amount of 31200 nm ³ / h, which has the following composition (% vol.): CO - 54; СО ₂ - 0.7; H ₂ - 44; H ₂ O - 0.1; gas temperature - 400 ° С, calorific value - 11540 kJ / m ³ . The energy potential of the synthesis gas is 360 GJ, the thermal capacity for the combustion of synthesis gas is 100 MW.

A slag melt is formed in an amount of 1796 kg / h with a temperature of 1550 ° C, which is discharged continuously. A metal alloy is formed in an amount of 270 kg / h with a temperature of 1550 ° C, which is periodically withdrawn once every 6 hours from the opposite side from the place of removal of slag melt.

In the process of coal gasification, gaseous and condensed products are formed, the mineral part of coal is melted, iron and other metals of the mineral part of the fuel are reduced, and the melt is divided into metallized and non-metallized (slag) phases.

Formed synthesis gas in an amount of 31130 nm ³ / hour, which has the following composition (% vol.): WITH - 55; СО ₂ - 0.7; H ₂ - 44.23; H ₂ O - 0.1; gas temperature - 400 ° С, calorific value - 11570 kJ / m ³ . The energy potential of the synthesis gas is 360 GJ, the thermal capacity for the combustion of synthesis gas is 100 MW.

Example 5

Key parameters for steam gasification of brown coal

. Выход летучих (%) V^daf=48.The bath of oxide melt has the following dimensions: diameter 4.5 m, depth 1.25 m. Volume 19.875 m ³ . The density of the bath is 2.65 g / cm ³ . The melt mass is 52.7 tons. The bath temperature is 1450 ° C. Brown coal in the form of pieces of size 20..30 mm in the amount of 20740 kg / h is fed into the bath from above through loading devices. The working mass of brown coal (%): moisture W ^r = 39; ash Ar ^r = 7.3; sulfur S _op + S _k = 0.4; carbon C ^r = 37.4; hydrogen H ^r = 2.6; nitrogen N ^r = 0.6; oxygen O ^r = 12.7. Net calorific value of coal $$Q_n^p=13.02MD\mathrm{well}/\mathrm{to}g$$

. The yield of volatile (%) V ^daf = 48.

When pieces of coal get on the surface of the melt, the pyrolysis of coal occurs with the formation of coke, which floats in the melt. In the working space of the bath, a suspension is formed, into which water vapor is supplied in the amount of 8730 kg / h.

Electric energy is introduced into the working space of the bath, which is converted into thermal energy due to the spreading of current through liquid and solid materials. Due to this thermal energy, the melt temperature is maintained at 1400 ... 1600 ° С, and the course of endothermic reactions is ensured.

The specific power consumption determined from the energy balance w _el = 5.08 MJ / kg and the solid fuel consumption G = 20740 kg / h determines the active power of the installation

$$P_a=\frac{G\cdot w_{\mathrm{uh}l}}{3600}$$

$$P_a=\frac{20740*5.08}{3600}=\mathrm{41,966}M\mathrm{AT}t$$

Power coming to one electrode, W

$$P_{\mathrm{uh}a}=\frac{{10}^6\cdot R_{\mathrm{but}}{\eta }_{\mathrm{uh}l}}{m}$$

where m = 3 is the number of electrodes, η _el = 0.92 is the electrical efficiency.

$$P_{\mathrm{uh}a}=\frac{\mathrm{41,966}\cdot 0.92\cdot {10}^6}{3}=12870000\mathrm{AT}t$$

Electrode current

$$I=\frac{p_{\mathrm{uh}\mathrm{but}}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{\mathrm{FROM}}$$

where C = 0.85 V / W ^1/3 - technological parameter

$$I=\frac{{12870000}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{0.85}=64610\mathrm{BUT}$$

The current is supplied through 3 graphitized electrodes. Active electric power 41.966 MW. Electrode current 64.61 kA. In the process of coal gasification, gaseous and condensed products are formed, the mineral part of coal is melted, iron and other metals of the mineral part of the fuel are reduced, and the melt is divided into metallized and non-metallized (slag) phases.

Formed synthesis gas in an amount of 31200 nm ³ / h, which has the following composition (% vol.): CO - 53; СО ₂ - 0.7; H ₂ - 45; H ₂ O - 0.1; gas temperature - 400 ° С, calorific value - 11540 kJ / m ³ . The energy potential of the synthesis gas is 360 GJ, the thermal capacity for the combustion of synthesis gas is 100 MW.

A slag melt is formed in an amount of 1510 kg / h with a temperature of 1550 ° C, which is discharged continuously. A metal alloy is formed in an amount of 230 kg / h with a temperature of 1550 ° C, which is periodically withdrawn once every 6 hours from the opposite side from the place of removal of slag melt. In the process of coal gasification, gaseous and condensed products are formed, the mineral part of coal is melted, iron and other metals of the mineral part of the fuel are reduced, and the melt is divided into metallized and non-metallized (slag) phases.

Example 6

The main parameters in the oxygen gasification of brown coal

. Выход летучих (%) V^daf=48.The bath of oxide melt has the following dimensions: diameter 4.5 m, depth 1.25 m. Volume 19.875 m ³ . The density of the bath is 2.65 g / cm ³ . The melt mass is 52.7 tons. The bath temperature is 1450 ° C. Brown coal in the form of pieces of 20 ... 30 mm in the amount of 30500 kg / h is fed into the bath from above through loading devices. The working mass of brown coal (%): moisture W = 39; ash Ar ^r = 7.3; sulfur S _op + S _k = 0.4; carbon C ^r = 37.4; hydrogen H ^r = 2.6; nitrogen N ^r = 0.6; oxygen O ^r = 12.7. Net calorific value of coal $$Q_n^p=13.02MD\mathrm{well}/\mathrm{to}g$$

. The yield of volatile (%) V ^daf = 48.

When pieces of coal get on the surface of the melt, the pyrolysis of coal occurs with the formation of coke, which floats in the melt. In the working space of the bath, a suspension is formed, into which oxygen is supplied in an amount of 7990 m ³ / h.

Electric energy is introduced into the working space of the bath, which is converted into thermal energy due to the spreading of current through liquid and solid materials. Due to this thermal energy, the melt temperature is maintained at 1400 ... 1600 ° С, and the course of endothermic reactions is ensured.

The specific power consumption determined from the energy balance w _el = 0.1 MJ / kg and the solid fuel consumption G = 30500 kg / h determines the active power of the installation

$$P_a=\frac{G\cdot w_{\mathrm{uh}l}}{3600}$$

$$P_a=\frac{30500*0.1}{3600}=0.847M\mathrm{AT}t$$

Power coming to one electrode, W

$$P_{\mathrm{uh}a}=\frac{R_{\mathrm{but}}{\eta }_{\mathrm{uh}l}{10}^6}{m}$$

where m = 3 is the number of electrodes, η _el = 0.92 is the electrical efficiency.

$$P_{\mathrm{uh}a}=\frac{0.847\cdot 0.92\cdot {10}^6}{3}=259800\mathrm{AT}t$$

Electrode current

$$I=\frac{p_{\mathrm{uh}\mathrm{but}}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{\mathrm{FROM}}$$

where C = 0.85 V / W ^1/3 - technological parameter.

For installations of electrothermal gasification of brown coal, the values of the technological parameter determined by physical and mathematical modeling are C = 0.85 V / W ^1/3

$$I=\frac{{12870000}^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}{0.85}=64610\mathrm{BUT}$$

The current is supplied through 3 graphitized electrodes. Active electric power 0.847 MW. Electrode current 4.79 kA. In the process of coal gasification, gaseous and condensed products are formed, the mineral part of coal is melted, iron and other metals of the mineral part of the fuel are reduced, and the melt is divided into metallized and non-metallized (slag) phases. Formed synthesis gas in an amount of 31200 nm ³ / h, which has the following composition (% vol.): CO - 69; СО ₂ - 0.7; H ₂ - 29; H ₂ O - 0.1; gas temperature - 400 ° С, calorific value - 11540 kJ / m ³ . The energy potential of the synthesis gas is 360 GJ, the thermal capacity for the combustion of synthesis gas is 100 MW.

A slag melt is formed in an amount of 2225 kg / h with a temperature of 1450 ° C, which is discharged continuously. A metal alloy is formed in an amount of 335 kg / h with a temperature of 1550 ° C, which is periodically withdrawn once every 6 hours from the opposite side from the place of removal of slag melt. In the process of coal gasification, gaseous and condensed products are formed, the mineral part of coal is melted, iron and other metals of the mineral part of the fuel are reduced, and the melt is divided into metallized and non-metallized (slag) phases.

The technology of electrochemical gasification, despite the use of relatively expensive electricity, allows combining metallurgical and energy technologies with synthesis gas, metal alloy and slag in one process, reducing the total energy costs compared to separate technologies for metallurgical reduction of oxides and gasification, in addition, you can use the installation of electrothermal gasification as a way of regulating the maximums of electric load, loading electrot rmicheskie gasifiers maximum at night and garnering generator gas in gas holders.

Claims (1)

The method of gasification of solid types of carbon fuel, including heating, pyrolysis of a sealed electrode furnace of carbon fuel supplied to a bath with molten slag while passing gasification agents through the slag melt, as well as passing electric current, removing synthesis gas, slag and metal alloy from the working space of the furnace, characterized in that a three-phase electric current is passed through the slag melt, the value of which is determined in accordance with the consumption of solid fuel and taking into account m of required power, determined from the expression:

where - G - solid fuel consumption in an electric furnace, kg / h,
w _el - specific consumption of necessary electricity, determined by physical and mathematical modeling, equal to:
- for gasification of coal and use in the gasification process as a gasification agent, an oxygen-vapor mixture of 2.20-2.356 MJ / kg, water vapor 7.0-7.23 MJ / kg, oxygen 0.20-0.23 MJ / kg;
- for gasification of brown coal and peat and use in the gasification process as a gasifying agent, an oxygen-vapor mixture of 2.50-2.83 MJ / kg, water vapor 5.0-5.08 MJ / kg, oxygen 0.08-0.1 MJ / kg;
3600 - conversion factor kg / h to kg / s, based on which the power per one electrode is determined:

where 10 ⁶ is the power conversion factor in watts, η is the electrical efficiency,
m is the number of electrodes equal to 3,
then determine the amount of current per one electrode:

where C is the technological parameter, which is a complex characteristic of the electrotechnological regime of the installation of electrothermal gasification of solid fuels, the values of the parameter C determined by physical and mathematical modeling are 0.88 V / W ^1/3 for gasification of coal, 0.85 V for brown coal gasification / W ^1/3 .

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