RU2378318C2 - Method and device for thermal processing of solid fuel thus obtaining semicoke, gas and liquid products - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: initial fine-grained fuel is supplied from silo 1 with screw feeder 2 to flash drier 3 whereto drying agent - exhaust gas of heat recovery boiler 4 is supplied from below. In dry fuel cyclone 5, dried fuel is deposited and supplied with screw feeder 6 to mixer 7 whereto hot solid heat carrier - semicoke of processed fuel is also supplied from heat carrier cyclone 8. Mixture of dried fuel and solid heat carrier is supplied via chute to rotary cylindrical reactor 9 wherein the fuel is heated and decomposed, and pyrolysis vapour gases are evolved. Fuel mixed with heat carrier is discharged through discharge throat 10 to dust chamber 11 equipped with built-in cyclones 12 and 13. In order to provide operation of cyclones, there provided is blower 14 by means of which some part of steam-gas mixture is transported via gas pipeline 28 to muffle 15.

EFFECT: increasing output of solid product of thermal processing and increasing energy efficiency of the process.

8 cl, 1 dwg

Description

The invention relates to methods and installations for the thermal processing of solid fuels - pyrolysis to obtain semi-coke, gas and liquid products and can be used in coal processing, ferrous metallurgy and energy.

The aim of the invention is to increase the yield of solid thermal processing product - semi-coke and increase energy efficiency (energy efficiency) of the process.

A known method of thermal processing of coal, including crushing the source coal and drying it with flue gases of a fluidized bed coke heater, pyrolysis of coal in a fluidized bed pyrolyzer, transporting a mixture of pyrolyzed coal with a coolant from a pyrolyzer to a fluidized-bed coke heater via a U-shaped coke pipe from the pyrolyzer of the mixture in the coke heater by partially burning the combustible substances contained in it and returning the heated mixture as a solid heat carrier from the coke heater a pyrolyzer through a U-shaped coke pipe, unloading the finished product - semi-coke from the fluidized bed of the pyrolyzer using a screw feeder (Copyright certificate No. 794063, priority 24.04.78, registered 08.09.80, Publish. 07.01.81, Bulletin No. 1 (51) M Cl ³ S10V 49/00 (53), UDC 662.74 (088.8).

The disadvantage of this method is to reduce the yield of the solid product of pyrolysis - semi-coke due to its partial combustion in a coke heater (technological furnace) in order to obtain the heat necessary for the implementation of the technological process - drying and pyrolysis of the processed fuel.

A known method of thermal processing of fine-grained fuel, including drying the fuel, pyrolyzing it by heating with a solid heat carrier to produce steam-gas products (GWP) and semi-coke, removing the GWP, cooling them, feeding the semicoke to the furnace and burning it to obtain a solid heat carrier, is fed to the pyrolysis stage.

Copyright certificate SU 1213748, СВВ 49/16 dated 12.11.82.

The disadvantage of this method, as well as the previous analogue, is the decrease in the yield of the target product - semi-coke due to its partial burning.

A known power plant containing a boiler with a fluidized bed furnace, in which there is an air heater connected respectively to a compressor and a combustion chamber of a turbine connected to an exhaust pipe of the boiler furnace, characterized in that it further comprises a pyrolyzer reactor connected by transfer pipes to the furnace and a gas outlet pipe - with a combustion chamber of a gas turbine.

Copyright certificate SU 1269578 A1 dated 06/27/84.

The disadvantage of this installation is the burning of all obtained by pyrolysis of semicoke, which is a valuable high-quality fuel and reducing agent.

The closest technical solution is the method and installation for the pyrolysis of fine-grained shale, adopted by us as a prototype and known as the Haloter process, published in the “Shale Processor Handbook”, ed. M.G. Rudina. Leningrad, Chemistry, 1988

Fine-grained slate (class 0–20 mm) is supplied by a screw feeder to an air-fountain dryer, in which it is dried by the physical heat of the flue gases from the recovery boiler. The dried shale is precipitated from the aerosuspension in a dry shale cyclone and is fed through a mixer to a rotating drum reactor, in which it is heated to a temperature of 480-500 ° C by mixing it with shale ash - a solid heat carrier having a temperature of 800-850 ° C and supplied into the reactor through a mixer from a heat-carrier cyclone, in which shale ash is deposited from an aerosuspension consisting of shale ash and exhaust flue gases from an aero-fountain furnace (AFT). In AFT, the mixture of semicoke and ash coolant, which enters it from the reactor through a dust chamber using a screw feeder, is heated to 800–850 ° C by burning a combustible residue of semicoking of shale in the AFT. For this, heated air blast is fed to the AFT through an ash heat exchanger. A bypass is installed between the AFT and the heat carrier cyclone on the flue gas path, which directs one part of the air suspension to the heat carrier cyclone, and the other part to the ash cyclone, from which the precipitated shale ash enters the ash heat exchanger - the air heater, and the AFT exhaust gases from the ash cyclone are sent to the boiler -recycler. Dry shale cyclone exhaust gases are cleaned in an electrostatic precipitator. The gas-vapor mixture of the semicoking of shale formed in the reactor, after dedusting with the help of cyclones placed in the dust chamber, is sent to the condensation and trapping system for the liquid products of shale pyrolysis.

The disadvantage of this method and installation is the burning of the organic part of the solid coolant - semi-coke circulating in the installation in an airborne technological furnace - AFT, which, when processing solid fuel, such as coal, in order to obtain semi-coke as the target product, reduces its yield, i.e. reduces the efficiency of the process.

In order to eliminate this drawback, to maximize the yield of the target product - semi-coke and expand the scope of its application, a method and apparatus for the pyrolysis of solid fuel with a solid heat carrier-semicoke are proposed, which differ from the prototype described above in that the burning of semicoke is excluded from the process as a source heat to conduct the process using steam-gas mixture or pyrolysis gas, burned in a special muffle, and the resulting "inert" - not containing oxygen products Combustion cycles (due to their combustion with an excess air coefficient α <1.0) are used to heat solid coolant.

Thermal processing of solid fuel (coal) is as follows (see drawing). The initial fine-grained fuel (class 0–20 mm) is fed from the hopper 1 by a screw feeder 2 to the airborne dryer 3, in which the drying agent — exhaust gases from the recovery boiler 4 — is fed from below. In the dry fuel cyclone 5, the dried fuel is deposited and transferred by the screw feeder 6 into the mixer 7, where from the cyclone of the coolant 8 also receives hot solid coolant - semi-coke of the processed fuel. The mixture of dried fuel and solid heat carrier flows into the drum rotary reactor 9, in which the fuel is heated and decomposes with the release of combined-cycle pyrolysis products.

The temperature of the solid coolant entering the mixer is 800–850 ° С, and the temperature of fuel pyrolysis in the reactor is 480–500 ° С (and depends on the type of fuel).

The mixture of fuel and coolant through the discharge neck 10 is discharged into the dust chamber 11, equipped with built-in cyclones 12 and 13, designed to dedust the vapor-gas mixture (ASG). To ensure the operation of the cyclones, a supercharger 14 is provided, with which a part of the gas-vapor mixture is transported further through the gas pipeline 28 to the muffle 15, in which it is burned, and the combustion products are sent to the cylinder - a conical aero-fountain heater 18 (AFS) installed between the muffle 15 and the coolant cyclone 8. Another excess portion of the gas-vapor mixture is used as fuel, for example, in a gas-vapor plant (CCGT), which provides electric power for the production of semi-coke.

The entire semi-coke discharged from the reactor 9 from the dust collection chamber 11 by the screw 16 is fed to the riser 17 connected to the AFS 18, in which the solid heat carrier - the semi-coke is heated with hot gases - combustion products of vapor-gas mixture IV or pyrolysis gas XVI entering the muffle 15. Muffle 15 is connected through a gas duct to the riser riser 17 AFN 18, as well as the discharge IV pipe 28 and the discharge XVI pipe 29.

In addition to the indicated flows IV and XVI, the following are sent to the muffle 15:

the air flow X from the air heater 23 - for burning combustible gases supplied to the muffle, the pyrolysis gas stream XVII - from the condensation system, the flue gas VI and water vapor VII flows from the recovery boiler 4 - for temperature control.

The gas suspension leaving the AFS, consisting of gas and semicoke, is divided into 4 streams using flow dividers - bypasses 19 and 20.

After the first bypass 19, one stream is directed to the heat transfer medium cyclone 8, and the second to the bypass 20, which separates the gas suspension into a stream directed to the commodity semi-coke cyclone 21 and a stream directed to the next bypass 22 in the course of the stream. From it, the flow is directed either to the cyclone 24, from which the hot semi-coke deposited in the cyclone is fed through the hopper 39 by pneumatic transport to the furnace of the blast furnace, or all gas suspension of flue gas and semi-coke, bypassing cyclone 24, is sent to the blast furnace.

Commercial semi-coke deposited in cyclone 21 is sent to a heat exchanger — an air heater 23 and is discharged in a cooled form to hopper 40, and the off-gas from the cyclone semi-coke 21 is sent to a waste heat boiler 4. The exhaust gases from the dried fuel cyclone 5 are cleaned in an electrostatic precipitator 25.

The waste heat boiler is equipped with a blower 26, and air is pumped into the muffle 15 through an air heater 23 with a blower 27.

The drawing also shows a system of condensation of liquid pyrolysis products, consisting of a heavy oil scrubber 31, barillet 32, a refrigerator - a heavy oil condenser 33, a tank for heavy oil 34, a distillation column 35, a refrigerator - a condenser of gasoline and tar water 36, a separator 37, a gas blower 38 .

When burning a vapor-gas mixture IV in a muffle, it is fed into the muffle through a pipeline 28, and when burning pyrolysis gas XVI, freed from liquid products, through a pipeline 29.

The drawing shows the following flows: I - solid fuel (brown coal); II - dried fuel; III - heat carrier - semicoke; IV - vapor-gas mixture; V - flue gas with entrainment of fuel particles; VI - flue gas - to dry the fuel and to dilute the gases in the muffle; VII - water vapor; VIII - precipitated fuel dust; IX - hot gas suspension of flue gas and semi-coke from AFS; X - air blast; XI - heavy resin; XII - heavy fraction of medium resin; XIII - resin gas turbine fraction; XIV - phenolic pyrolysis water - for processing; XV - gasoline fraction; XVI - pyrolysis gas; XVII - total resin; XVIII - pneumatic transport of semi-coke in a blast furnace; XIX - gas suspension of semi-coke and flue gases; XX - chilled semicoke.

An example implementation of the method.

When 130-140 t / h of brown coal is supplied to the unit, which corresponds to a processing of 0.9-1.0 million tons per year, with a continuous annual resource of 7000 hours, as a result of pyrolysis, 40-45 t / h of marketable pulverized semi-coke can be obtained suitable for blowing without cooling in the hearth of a blast furnace.

The total amount of useful heat in the pyrolysis products is ~ 85%, including ~ 60% in commercial semi-coke, and ~ 25% in semi-coke gas (PCG) and liquid products, PCG yield ~ 15 t / h, and liquid products ~ 12. 0 t / h The total heat consumption for own needs when burning part of the gas-vapor mixture or PCG and losses are equivalent to burning ~ 3.0-4.0 t / h of semi-coke. Flue gas emissions will amount to 40.0 t / h when air is supplied to heat the solid coolant at α <1.0 (5-6% of the stoichiometric).

Claims (8)

1. A method of producing semicoke from solid fuel by heating it with a solid heat carrier and pyrolysis, drying solid fuel, mixing it with a solid heat carrier - hot semi-coke heated by a gas heat carrier, a pyrolysis step for a mixture of fuel and a solid heat carrier to produce a semicoke and steam-gas mixture, stage cooling, condensation and separation of the vapor-gas mixture into liquid products and a pyrolysis gas, characterized in that a gas coolant is used to heat the solid heat carrier, which is obtained removed by combustion in a muffle part of the steam-gas mixture formed during the pyrolysis of the solid fuel being processed. 2. The method according to claim 1, characterized in that the pyrolysis gas obtained after condensation of the liquid pyrolysis products and the liquid pyrolysis products are partially burned, and the resulting combustion products are used to heat the solid heat carrier, to produce steam in the recovery boiler and to generate electricity using a combined cycle gas installation. 3. The method according to claim 1, characterized in that the combustion process is carried out with a lack of air - coefficient of excess air α <1. 4. The method according to claim 1, characterized in that the residual products and flue gases after the air heater are sent for afterburning to a waste heat boiler. 5. The method according to claim 1, characterized in that the resulting hot semi-coke and carrier gases are fed together without cooling to the furnace of the blast furnace, and the combined-cycle products and pyrolysis gas not used in the solid fuel pyrolysis technology are supplied to the combined-cycle plant to generate electricity used pyrolysis technology. 6. The method according to claim 1, characterized in that the gas suspension stream consisting of semicoke and combustion products in a muffle of a gas-vapor mixture or pyrolysis gas is sent to the first bypass, after which one stream is sent to the heat carrier cyclone, and the second stream to the other bypass separating the gas suspension into a stream directed to the cyclone of a commodity semi-coke, and into a stream directed to the next bypass along the stream, and then either into a cyclone from which the precipitated semi-coke is fed into the furnace of a blast furnace, or the entire gas suspension, bypassing the cyclone, is sent to blast furnace. 7. Installation for the pyrolysis of solid fuels using a solid coolant to obtain the target product is a semi-coke, consisting of an aero-fountain dryer connected to a dry fuel cyclone, a solid coolant cyclone, and these cyclones are connected through a mixer to a drum reactor equipped with a dust precipitation chamber with cyclones, characterized the fact that the installation comprises an aero-fountain heater, consisting of a vertical riser and a cylindrical aero-fountain device, and connected to a gas duct m flue gases, wherein the elevating vertical riser communicates with a muffle for burning gaseous or liquid fuels pyrolysis connected to conduits supplying air, steam, flue gas, gas mixture, gas pyrolysis, liquid pyrolysis products. 8. Installation according to claim 7, characterized in that three by-pass sequentially installed in the exhaust gas duct.