RU2339673C1 - Method for thermal processing of slate coal with production of liquid and gaseous fuel and also cement clinker and facility for its employing - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to thermal processing of slate coal and can be employed in slate coal processing industry, power engineering, for production of chemical raw material, liquid and gaseous power carriers, for production of cement, concrete, and also in agriculture. Method incorporates crumbling, drying of fine-grain slate coal (0-15 mm) with smoke fumes in a dryer of aero-fountain type, mixing of slate coal with a solid heat carrier for heating to temperature of pyrolysis and pyrolysis in a reactor with formation of a steam-gaseous mixture of pyrolysis products, directed to condensation, and mineral residue of pyrolysis. Part of organics of the mineral residue is burned in aero-fountain process fire chamber at temperature of de-carbonization not lower, than 900-1000°C and coefficient of circulation of a solid heat carrier 2-3 followed with formation of aero-suspension of hot smoke fumes and de-carbonized ashes. A required amount of ashes is separated from smoke fumes in a divider, the said ashes as a solid heat carrier are directed to mixing with slate coal. The excess of ashes, separated in the cyclone from hot smoke fumes is supplied together with added de-carbonised lime with additives into a mixer of the clinker charge and further for burning of cement clinker into a cement furnace. Following afterburning in an exhaust-heat boiler hot smoke fumes are directed into dryer of aero-fountain type for drying of slate coal.

EFFECT: production of liquid fractions with low contents of mechanical impurities and production of cement clinker.

5 cl, 1 ex, 2 dwg

Description

The invention relates to the field of thermal processing of oil shale and can be used in the oil shale industry, energy, for the production of chemical raw materials, liquid and gaseous energy carriers, building materials: cement, concrete, as well as in agriculture for the use of the pyrolysis mineral residue in reclamation of acid soils.

The method includes thermal degradation of the initial carbonate shale with a solid heat carrier in a solid heat carrier (UTT) or thermal contact coking unit (TKKU) with the formation of a vapor-gas mixture and decorbonized hot pyrolysis ash by adding the necessary stoichiometric amounts of decarbonized limestone and clay to the hot ash to produce a calcined shear.

The method also includes purification of the vapor-gas mixture from mechanical impurities, condensation of the vapor-gas mixture with the release of liquid fractions and high-calorie semi-coke gas, which is sent as an energy carrier for decarbonization of the charge, and clinker burning in a cement kiln.

EFFECT: obtaining from the shale liquid fractions with a low content of mechanical impurities, including those going to the preparation of high-quality motor and energy fuels, as well as obtaining cement clinker from the mineral part of the shale.

The invention relates to the field of thermal processing (pyrolysis) of primarily combustible carbonate shales and can be used in the oil shale and petrochemical industries, energy, in the production of motor and energy fuels, in the production of building materials and agriculture for the reclamation of acid soils with the mineral residue of pyrolysis of shales.

A known method of processing high-ash carbonate oil shales, including drying shredded shale with flue gas, heating the dried fuel with an ash solid heat carrier (TT) to form a gas-vapor mixture and a coke-ash residue (KZO), burning the organic part of KZO in an air blast stream with an increase in the temperature of the TT and returning it to the stage of pyrolysis in the reactor.

Chilled ash in an amount adequate to its content in the mineral part of the initial shale is removed from the process, and flue gases are sent to dry the shale, followed by their release into the atmosphere. Combustion gas treatment is carried out in an air fountain furnace with a lack of oxygen, and the chemical and physical heats of flue gases and ash are disposed of in an ash heat exchanger and a waste heat boiler. AU USSR No. 1754760, СВВ 53/06.

A known installation for the thermal processing of high-ash solid fuels, such as oil shale, containing a sequentially arranged dryer, a separator for separating a drying agent, a reactor for thermal decomposition of shale, a separator for separating a solid heat carrier connected to the reactor, and a separator for separating ash connected to a waste heat boiler , an aero-fired firebox connected to a solid heat separator in front of the mixer, an ash heat exchanger connected to an ash separator.

A known installation for the thermal processing of high-ash solid fuels, such as oil shale, containing successively arranged crushed fuel dryer, a separator for separating a drying agent, a reactor for thermal decomposition of solid fuel, a furnace, a separator for separating solid coolant (TT) connected to the upper part of the mixing unit, a reactor for thermal decomposition of dried shale, an ash heat exchanger, a waste heat boiler (G.P. Stelmakh, B.I. Tyagunov, V.I. Chikul, and others. Oil shale 1985, 2/2, pp. 181-188).

The disadvantages of the aforementioned known method and installation is that they cannot provide a decarbonized charge in a continuous technical process for the formation of clinker and its roasting in a single complex in order to obtain cement.

There is a method of non-waste processing of oil shale in a fine-grained state in a fluidized bed in aggregates with a unit capacity for shale being processed of 1.0 million tons / year (UTT 3000).

The resulting semi-coke (ash) is mixed with limestone. When the content of decarbonized ash (68-70%) in a mixture with decarbonized limestone (30-32%) provides a clinker mixture, corresponding to the generally accepted parameters of cement production.

A mixture of semi-coke with limestone after decorburization is fired in rotary kilns to obtain a cement clinker, during grinding of which portland cement is obtained with active additives (Handbook of a shale processor under the editorship of M.G. Rudin and N.D. Serebryannikov L., “Chemistry” , LO, 1988, p. 189).

A known installation processing carbonate oil shale containing a crusher, dryer, cyclone separator for separating a drying agent, a thermal decomposition reactor, a furnace for producing a solid heat carrier connected to a solid phase separator, an ash heat exchanger for cooling the mineral part, a waste heat boiler (Oil shale V12. No. 4, 1994-1995, pp. 357-361).

The main disadvantage of the above methods and installation is that while ensuring the completeness of combustion of the combustible components of the coke-ash residue, it should be cooled in an ash heat exchanger. In this case, the implementation of the production of cement requires in such a closed process chain the additional cost of heat for the decarbonization of the mixture and firing of clinker upon receipt of cement.

The closest - the prototype of the present invention is a method and installation for thermal processing of fine-grained slate using a solid heat carrier.

To achieve the desired technical result, the fuel is dried with exhaust flue gases, heated with a solid heat carrier to form a gas-vapor mixture and a coke-ash residue, the latter is burned in an air blast stream to form a gas suspension, the solid phase is separated from the gas suspension and returned to the heating stage as a solid heat carrier, the remaining part is separated gas suspension to the solid phase with its output as chilled ash and flue gases, followed by the return of flue gases to the drying stage.

The installation comprises a dryer located in series, a separator for separating the drying agent, a thermal decomposition reactor for solid fuel, a technological furnace, a first separator for separating the solid phase — the solid coolant, the output of the solid phase of which is connected to the top of the mixer connected by the reactor, and a second separator for separating the solid the output of the gas phase of which is connected to the dryer, and the installation further comprises a heat exchanger for cooling the ash (mineral residue) to 80-100 °, input, which is connected to the output of the solid phase of any of the existing or additionally installed separator for separating the solid phase, and the output is connected to the bottom of the aero-fountain furnace (AFT).

The combustion of the coke ash residue in AFT is carried out at the optimum fuel-air ratio (alpha = 0.95-1.05), and the temperature in the gas suspension is maintained within 650-900 ° C.

Due to the maintenance at the burning stage (in AFT) of a temperature lower than the decarbonization temperature of the mineral components of shale ash (below 780 ° C), the sulfide sulfur content in kukersite ash decreases sharply from 1.5-1.8 to 0.1-0.3 wt.%. The ash obtained by the proposed technology, without additional heat treatment, can be used as an ameliorant to neutralize acidic soils and as a bactericidal drug in the fight against bacteriosis of agricultural plants.

The disadvantage of this method and installation is the need to heat from a cold state in order to carbonize the mixture to obtain clinker, additionally consuming heat and energy.

The solution of the set technological task offers the following: to achieve complete decarbonization of the mineral residue in order to obtain a clinker mixture in a single technological chain, it is necessary to increase the temperature of the combustion of coke ash residue after pyrolysis in a flowing layer to 900-1000 ° C, but below the melting of ash, which ensures decarbonization of shale ash . Melting ash of carbonate shales occurs at 1300-1400 ° C. An increase in temperature during the formation of a solid coolant during the afterburning of organics in a coke ash residue (KZO) leads to a decrease in the multiplicity of circulation of a solid coolant to 2.5-3.0, which is permissible for a pyrolysis reactor and a technological furnace. Heated decarbonized ash (76.08%) is mixed with an additional amount of decarbonized added limestone (22.84%) and clay (1.08%), mixed and sent as a charge to calcination in a cement kiln.

Utilization of flue gas heat after a technological furnace, decarbonization, firing in a cement kiln is carried out in a waste heat boiler. It is installed on the flue gas stream before the drying step. In it, combustible components contained in flue gases are burned in an air blast stream with an air excess coefficient of alpha = 0.95-1.05. The potential heat contained in these components is 5-8% of the potential heat of the processed oil shale.

The technical solution of this problem is a method for the thermal processing of high-ash combustible shales, including drying the crushed fuel with flue gases, heating the dried fuel with a solid heat carrier to form a gas-vapor mixture, burning a coke ash residue at 900-1000 ° C in an air blast stream to form a gas suspension of a combustible decarbonized solid heat carrier separation of the remaining gas suspension into decarbonized ash and flue gases, followed by return of the flue gases to drying and to the waste heat boiler, and decarbonized ash (76.08%) is sent for mixing with additional decarbonized limestone (22.8%) and clay (1.08%).

The block diagram of the proposed method for the thermal processing of oil shale with the development of cement clinker image in figure 1.

The method represents a single technological system of parallel successive stages of a low-waste complex technological process for processing shale to produce cement clinker.

Stage 1, 2, 3, 4 - pyrolysis compartment of the installation with a solid coolant, 5 - condensation compartment.

Stages 6, 7, 8, 9, - a cement clinker production unit having functional technological connections (flows) with pyrolysis and condensation units.

Carbonate shale I (88-85 wt.%) Enters the preparation stage 1 (crushing by screening to 0-10 ~ 15 mm), then it is sent for drying with flue hot gases XI to stage 2. After drying, the shale with a temperature of ~ 120 ° C sent for mixing with a solid coolant (900-1000 ° C) and pyrolysis in a reactor, stage 3, with a temperature of 450-500 ° C, the amount of solid coolant (TT), stage 4, is determined by the afterburning temperature of the remaining organics and mass flow and is 200-300 wt.%, I.e. the multiplicity of circulation 2 ~ 3 at a temperature at the stage of afterburning of the coke ash residue of pyrolysis of 900-1000 ° C. If there is a lack of heat for some shales, additional fuel can be supplied with the aim of decarbonization of the short-circuit furnace in the technological furnace to maintain the temperature of decarbonization.

The decarbonated mineral pyrolysis residue — KZO, IX, and limestone prepared in a grinder 9 (stage 1) and a decarbonizer (stage 6) are sent for mixing (stage 7), after which the charge is sent to the kiln (stage 8, 1300 ° С).

The proposed proven composition of the mixture for clinker consists, wt.%: 76.08 decarbonized KZO, 22.84 decarbonized limestone and clay - 1.08.

Figure 1 shows the main input and output material flows, including intermediate at the stages of pyrolysis, decarbonization, firing, etc., which are indicated, as in figure 2, in Roman numerals: I - slate, IX - decarbonized ash KZO, XI - hot flue gases, XIII - cold flue gases, XIV - semi-coke gas, XV - additional limestone, XVI - clay, XVII - clinker, XVIII - resins, XIX - phenolic water.

In Fig.2 presents a schematic flow chart of the proposed installation and method, including the separation of the pyrolysis of oil shale with the production of liquid fractions of resin and semi-coke oven gas, as well as the separation of the production of cement clinker from the mineral residue of pyrolysis of oil shale in accordance with the stages of a complex technological process shown in Fig.1 and main material flows (I-XVII).

The installation works as follows: Technological scheme (with the UTT-3000 unit).

The oil shale (I) after the crusher 9 (fraction 0-10 ~ 15 mm) is fed by a screw feeder 1 into the airborne dryer 2, where it is dried by the heat of the process flue gas. The air suspension of dry shale and heat carrier gas is separated in cyclone 3. Dry shale (II) is fed by a screw feeder 4 through a mixer 5 into a rotating drum reactor 6 (reactor diameter 5 m, length 15 m, speed 1 rpm). In the mixer and reactor, due to the heat of the stream (III) received from cyclone 13 of the ash coolant (900-1000 ° C), thermal decomposition of shale occurs at a temperature of 480-500 ° C. Flue gases VII after drying out of cyclone 3, are cleaned from dust in additional cyclones and an electrostatic precipitator 17 and then, at a temperature of about 150 ° C, are released into the atmosphere (XIII). After the screw 18, the ash (ameliorant) XX is sent to the consumer. The gas-vapor mixture (ASG) (V) leaving the reactor 6 enters the dust chamber 7, where it is cleaned of dust in the built-in cyclones 10, and then into the condensation system 21-28. In the column 21, the gas collector 22 and the air condenser 23, the heavy oil entering the vessel 24 is condensed. In the column 25, the heavy fraction of the middle oil and the gas turbine fuel fraction are condensed by irrigation with a cooled gas turbine fraction. Then in the air condenser 26 the vapors of the pyrogenetic resinous resin and gasoline fraction are condensed, which are separated in the separator 27. The semi-coking gas (XIV) containing gas gasoline is sent to the decarbonizer 15 and the kiln clinker 30.

The mixture of semicoke and coolant ash (IV) from the reactor 6 enters the lower part of the dust chamber 7, from which it is fed by a screw feeder 8 into the airborne process furnace 11, where air (VIII) is supplied by the supercharger 19. In the furnace 11, the combustible residue of semi-coking is burned, due to which the entire mass of coolant ash is heated to the required temperature. The air suspension of the flue gases and hot ash (VI) through the bypass 12 is sent to the heat-transfer cyclone 13, in which the necessary amount of heat transfer to the mixer 5 is released. Excess ash is released in the cyclones 14, from which the hot gases are sent to the recovery boiler 16 (VII ), and ash (III) enters the batch mixer 29, where decarbonized limestone (IX) enters from 15. As a result of the afterburning in the waste heat boiler of residual combustible gas components (VII and XI), steam (40 atm, 440 ° C) is obtained (XII). Cooled to 500-600 ° C, the gas from the recovery boiler is fed to dryer 2. Slate ash collected by the electrostatic precipitator 17 can be sent through the pneumatic system to the reactor.

From the kiln 30 after cyclone 31, flue gases (XI) are sent to a waste heat boiler 16, the cement clinker (XVII) is removed from the installation for further processing. The required amount of limestone (XV) and clay (XVI) is fed through a crusher 9, a decarbonizer 15 and sent to a cement clinker in a batch mixer 29. The mixture (X) is fired in a furnace 30, from where the clinker (XVII) is sent to produce cement.

An example of the implementation of the process of pyrolysis of carbonate shales with the production of cement clinker, as well as liquid and gaseous pyrolysis products in a plant with a throughput capacity of (UTT-3000) of 3000 tons / day of oil shale or 139 tons / hour.

The plant receives 139 t / h of oil shale and 21.23 t / h of limestone, as well as additives (clay, pellets, etc., 1-2 t / h). After drying the shale to 120 ° C and feeding it to the mixer, where a solid coolant with a temperature of 900-1000 ° C (at K = 2-2.5) enters, the mixture is sent to a reactor with a pyrolysis temperature of 450-500 ° C. A steam-gas mixture leaves the reactor, which condenses, resulting in the formation of 18 t / h of tar, 3.2 t / g of phenolic water and 5500 km ³ / h of high-calorie (Q = 9 ÷ 10 thousand kcal / nm ³ ) coking gas, used for decarbonization of additional limestone and clinker firing. The decarbonized mineral residue (ash) leaving the pyrolysis compartment is 60.9 t / hr after the technological furnace and the hot ash cyclone mixed with decarbonized limestone with an additive (13.8 t / h) and the resulting clinker charge (74.7 t / h) ) sent to the cement kiln for firing, where the temperature is maintained at 1300 ± 50 ° С. This produces 72.5 t / h of clinker for the preparation of Portland cement-400.

Using the hot mineral pyrolysis residue decarbonized at the stage of TT formation, as well as our own high-calorie semi-coke pyrolysis gas for decarbonizing limestone and burning the clinker charge, leads to 30% heat and energy savings compared to separate stages of cement production by traditional technologies.

Figure 1. A flowchart of a method for the pyrolysis of shales with the simultaneous production of cement clinker.

1-5 stages of the pyrolysis compartment, 6-9 stage of preparation of cement clinker.

Stages: 1 - preparation of oil shale (crushing up to 10-15 mm), 2 - drying to 120 ° С, 3 - pyrolysis of 450-500 ° С, 4 - afterburning of coke ash residue (KZO) of pyrolysis at 900-1000 ° С at К = 2-3, 6 - decarbonization of limestone at 1000 ° C, 7 - preparation of the mixture, 8 - firing of clinker, 9 - preparation of additional limestone (crushing up to 0-5 mm). Streams: I - shale, XV - limestone, XIV - clay, IX - decarbonized KZO, XVI - semi-coke gas, XVIII - resin, XIX - phenolic water, XI - hot flue gases, XIII - cold flue gases, XVII - clinker.

Figure 2. Schematic diagram of the UTT-3000 unit with the simultaneous production of cement clinker

Equipment: 1 - a crude shale screw, 2 - an aerial dryer, 3 - a dry shale cyclone, 4 - a dry shale screw, 5 - a mixer, 6 - a drum reactor, 7 - a dust chamber with cyclones for cleaning a gas-vapor mixture (ASG), 8 - a screw semicoke, 9 - crushers sl. Izv., 10 - dust removal system captured by ASG cyclones, 11 - aero-fountain technological furnace (AFT), 12 - heat carrier bypass, 13 - heat carrier cyclone, 14 - ash cyclone, 15 - decarbonizer known. 16 - waste heat boiler, 17 - an electrostatic precipitator, 18 - augers of dust trapped by an electrostatic precipitator, 19 - air blowers into a decarbonizer and AFT, 20 - a waste heat boiler blower, 21 - a heavy oil scrubber (ТМ), 22 - a barrel (gas separator), 23 - ТМ condenser-refrigerator, 24 - TM capacity, 25 - distillation column, 26 - refrigerator-condenser of gasoline and tar water, 27 - separator, 28 - gas blower, 29 - charge mixer, 30 - clinker kiln, 31 - kiln cyclone, 32 - limestone and additives hopper, 33 - conveying screw.

Streams: I - shale in the flow of the drying agent, II - dry shale, III - coolant (ash), IV - semi-coke with coolant, V - vapor-gas mixture, VI - ash in the flue gas stream, VII - flue gas, VIII - air, IX - limestone dec., X - clinker charge, XI - hot flue gases, XII - steam, XIII - cold flue gases, XV - limestone, XIV - clay, XVII - cement clinker, XVIII - resins, XIXIII - tar resin, XX - - ash (ameliorant).

Claims (5)

1. The method of thermal processing (pyrolysis) of fine-grained carbonate-containing high-ash oil shales, including the stages of preparation, crushing, drying with flue gases of fine-grained shale (0 ~ 15 mm), mixing with a solid heat carrier to heat to the pyrolysis temperature, the pyrolysis stage in the reactor, with the formation of gas-vapor a mixture of pyrolysis products directed to condensation and the pyrolysis mineral residue, characterized in that the stage of burning part of the organics of the pyrolysis mineral residue is carried out at a deck temperature bonization not lower than 900-1000 ° C and a circulation coefficient of solid coolant 2-3 with the formation of an aerosuspension of hot flue gases and decarbonized ash, the required amount of ash is separated, which is sent as a solid coolant for mixing with shale, excess ash is separated from hot flue gases, which is mixed with added decarbonized limestone with additives in the clinker batch mixer and then goes to the stage of cement clinker firing, and hot flue gases after burning in the boiler - the utilizer goes to drying. 2. The method according to claim 1, characterized in that the supplied hot charge after the decarbonizer and mixer is sent for firing in a cement kiln. 3. The method according to claim 1 or 2, characterized in that the mixture of carbonate shales consists of 76.08 wt.% Pyrolysis ash, 22.84 wt.% Decarbonized limestone and 1.08% clay. 4. Installation for the thermal processing of oil shale to produce liquid and gaseous pyrolysis products and cement clinker, including a crusher, aero-fountain type dryer, a dried fuel mixer connected to a pyrolysis reactor connected to the process furnace, a condensation system for combined-gas pyrolysis products, an aerial process furnace, a solid heat carrier and hot flue gas flow divider connected to a mixer, characterized in that the output of the captured hot decarbonized gas The flue gas from the cyclone of hot flue gases supplied through the waste heat boiler to the dryer is connected to a clinker charge mixer containing an input of decarbonized limestone with additives; the mixer outlet is connected to a cement kiln. 5. Installation according to claim 4, characterized in that it contains a mixer for hot decarbonized mineral pyrolysis residue with decarbonized limestone with additives for the formation of a clinker charge, connected to a kiln to produce clinker.

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