CN112625720A - Cross-flow type coal mixing pyrolysis method and pyrolysis device - Google Patents
Cross-flow type coal mixing pyrolysis method and pyrolysis device Download PDFInfo
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- CN112625720A CN112625720A CN202011335908.XA CN202011335908A CN112625720A CN 112625720 A CN112625720 A CN 112625720A CN 202011335908 A CN202011335908 A CN 202011335908A CN 112625720 A CN112625720 A CN 112625720A
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B57/00—Other carbonising or coking processes; Features of destructive distillation processes in general
- C10B57/08—Non-mechanical pretreatment of the charge, e.g. desulfurization
- C10B57/10—Drying
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B49/00—Destructive distillation of solid carbonaceous materials by direct heating with heat-carrying agents including the partial combustion of the solid material to be treated
- C10B49/02—Destructive distillation of solid carbonaceous materials by direct heating with heat-carrying agents including the partial combustion of the solid material to be treated with hot gases or vapours, e.g. hot gases obtained by partial combustion of the charge
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B53/00—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G1/00—Production of liquid hydrocarbon mixtures from oil-shale, oil-sand, or non-melting solid carbonaceous or similar materials, e.g. wood, coal
Abstract
The invention discloses a cross-flow type coal mixing pyrolysis method and a pyrolysis device, wherein a longitudinal multilayer gas distribution and multilayer gas collection structure is adopted, gas-solid two-phase cross flow and counter flow are combined, uniform heat exchange and primary dust fall are realized simultaneously, dust-containing oil-containing high-temperature coal gas generated by pyrolysis is contacted with a medium-temperature material in a drying and carbonization transition section for heat exchange, the purpose of secondary dust removal is achieved, a part of heavy tar is condensed and is brought into the carbonization section by the dry coal for secondary pyrolysis, the coal gas separated out by the pyrolysis device has the characteristics of moderate temperature, low dust content and high light oil content, the working load and equipment investment of a gas purification system are obviously reduced, and the quality of the coal gas and tar products is improved.
Description
Technical Field
The invention belongs to the field of coal chemical industry, and particularly relates to a cross-flow type coal mixing pyrolysis method and a pyrolysis device.
Background
The coal pyrolysis refers to a thermal processing technology for obtaining coal gas (gas), coal tar (liquid) and semicoke (solid) by placing coal in an air or inert gas isolated environment and continuously heating the coal to a certain temperature to generate a series of physical changes and chemical changes. Pyrolysis is an important link in the coal thermal processing process, and is widely concerned due to the advantages of low processing temperature, simple process and operation and the like. The pyrolysis product is processed differently according to the property and the structural difference of the pyrolysis product, an industrial chain is extended, various chemical raw materials and various fine chemicals can be produced, and clean and efficient utilization of coal is realized.
The coal pyrolysis device can be divided into a plurality of moving beds, fluidized beds, rotary furnaces, belt furnaces and the like according to the furnace type, wherein an internally heated moving bed which takes high-temperature gas as a heat carrier and directly contacts gas and solid phases has the characteristics of relatively simple structure, no power part, low operation cost and the like, and is most widely applied in industry. But the technology has the defects of single production raw material, only treatment of 20-80mm lump coal, low tar recovery rate and the like. Along with the great improvement of the mechanization degree of coal mining, the lump coal is less and less, and more than 80 percent of the lump coal is mixed coal smaller than 30 mm. When the moving bed pyrolysis furnace is used for treating mixed coal, because of the small gaps in the furnace, the bed resistance is high, gas is easy to be short-circuited and difficult to be uniformly distributed, the gas-solid two-phase heat exchange efficiency is low, and the quality of a semicoke product is poor. If a multi-layer gas inlet and outlet structure is adopted in the pyrolysis furnace to reduce the height of a bed layer, the treatment capacity of a single furnace is reduced, the gas separation temperature is higher, and the heat utilization efficiency of the system is reduced. In addition, compared with lump coal, coal gas generated by mixed coal pyrolysis contains a certain amount of tar gas and also carries a large amount of dust, heavy tar is condensed due to the reduction of the gas temperature, and the dust and the tar are easy to bond and deposit in equipment and pipelines, so that the long-period operation of the equipment is influenced. Therefore, the method has important significance for reducing dust precipitation and avoiding heavy tar condensation in the mixed coal pyrolysis device.
In the prior art, a low-rank coal pyrolysis device can be divided into an external heating type and an internal heating type according to a heating mode, and can be divided into a moving bed, a fluidized bed, a rotary furnace and the like according to device types, wherein the internal heating type moving bed pyrolysis device is more and most mature in industry due to simple equipment structure and low operation cost. However, when the existing internal heating type moving bed pyrolysis technology is used for treating mixed coal with the particle size less than 30mm, the problems of non-uniform gas-solid heat exchange, low heat utilization efficiency, high gas dust content, difficult purification treatment, easy blockage of equipment pipelines, poor product quality and the like generally exist; the external heating type pyrolysis process has low single-furnace processing capacity due to obvious temperature gradient in the furnace, and is difficult to be applied industrially; the material in the fluidized bed or the rotary furnace pyrolysis device is severely disturbed, the gas dust amount is large, the pyrolysis gas containing dust and oil is separated out in a high-temperature form (400 ℃), the treatment process is complex, the system stability is poor, and the operation cost is high.
A thin-layer pyrolysis furnace, a pyrolysis device and a pyrolysis method for pulverized coal, which are disclosed in patent No. 201610282574.1, provide a thin-layer pyrolysis furnace, a pyrolysis device and a pyrolysis method for pulverized coal. The thin-layer pyrolysis furnace is internally and horizontally provided with a semi-open type gas outlet channel, and the structure of the thin-layer pyrolysis furnace is that the upper part is closed and the lower part is open; one end of the semi-open type gas leading-out channel is communicated with the exhaust hole, the other end of the semi-open type gas leading-out channel is connected with the wall surface opposite to the side wall surface of the furnace where the exhaust hole is positioned, the upper part of the semi-open type gas leading-out channel is opposite to the furnace top surface and has a distance, and the lower part of the semi-open type gas leading-; the semi-open type gas outlet channel and the heating wall have horizontal spacing; when coal exists, the coal in the inner space at the lower part and the inner space at the upper part form a cavity, the cavity forms an integral gas guiding channel, and pyrolysis gas escapes from the exhaust hole along the integral channel. The thin-layer pyrolysis furnace provided by the invention is an indirect heat exchange furnace type, aims to lead pyrolysis gas out of the furnace rapidly, thereby reducing the resistance of a bed layer, and has the characteristics of simple structure and good exhaust effect. However, the main problems of the thin-layer dry distillation are that the temperature is very high when the coal gas is separated out, a large amount of sensible heat is wasted, the heat utilization efficiency of the system is low, and the equipment is difficult to be large-sized and industrialized. In addition, the thin-layer pyrolysis furnace provided by the invention has the defects of high side wall temperature and low center temperature, and the semicoke is heated unevenly, so that the product undercooking condition is obvious.
201711100941.2 CN107858156A discloses a coal pyrolysis system, which comprises a pyrolysis unit, a coke quenching unit, a waste heat recovery unit, a dust removal purification device, an oil-gas separation purification device and an oil-water separation purification device, wherein the pyrolysis unit, the coke quenching unit, the waste heat recovery unit and the dust removal purification device are used for carrying out waste heat recovery and dust removal purification on high-temperature hot carrier gas discharged by the coke quenching unit; the oil-gas separation and purification device is respectively connected with the pyrolysis unit and the coke quenching unit. The primary cooling gas after oil-gas separation is directly introduced into the coke quenching unit to exchange heat with the high-temperature semi-coke, so that trace tar and organic liquid impurities in the primary cooling gas are decomposed into small molecular gas, and the gas purification process is shortened while the heat of the semi-coke is utilized. The method does not provide a targeted solution for mixed coal pyrolysis, and mixed coal is difficult to treat if the pyrolysis heating mode is gas-solid direct heat exchange. In the coke quenching unit, only the heat exchange principle of a cross flow mode is utilized, and the pyrolysis gas is used as a medium to cool the high-temperature semicoke, but the method cannot completely remove tar impurities in the gas, but increases the dust content of the gas, and the gas still cannot be utilized after the waste heat of the semicoke is recovered. Considering that the flue gas dry quenching technology and the water wall waste heat recovery technology are mature, the process flow provided by the invention is more complex, the operation cost is higher, and the process is not feasible economically.
201710831382.6 "CN 107723012B multistage fluidized bed pulverized coal pyrolysis and dust removal coupled coal tar gas preparation system and method" provides a multistage fluidized bed pulverized coal pyrolysis and dust removal coupled coal tar and gas preparation system and method, the system adopts a gas-solid heat carrier multistage fluidized bed pyrolysis process, pyrolysis raw gas is subjected to multistage cyclone dust removal and then exchanges heat with dried granular coal, heavy components of the raw gas are condensed on the granular coal and coated with fine powder to achieve the purpose of dust removal, and meanwhile, the heavy components are subjected to secondary pyrolysis to improve the quality of the coal tar; the semicoke pyrolyzed by the fluidized bed can be used as a filter material for particle dust removal after soot blowing to further filter and remove dust of the raw coke gas. The method uses a fluidized bed as a pyrolysis device and is only suitable for processing small-particle coal or pulverized coal with the particle size of less than 3 mm. In addition, the oily raw gas after multistage dust removal is introduced into the particle bed to achieve the purposes of dust removal and heavy oil removal, the gas dust removal process is complex, the pressure drop of equipment is large, the temperature of the gas in the whole process is not remarkably reduced, a large amount of tar loss is avoided, the system control difficulty is high, and the stable operation capability of the equipment is poor.
201410214844.6 Integrated device and process for desulfuration, dedusting and modification of coal pyrolysis gas, which is disclosed in CN104031693B coal pyrolysis gas desulfuration, dedusting and modification integrated device and process, raw gas from low temperature carbonization furnace or coke oven in coal directly enters into integrated moving bed purifier, and desulfuration, dedusting and modification process are completed under the condition of not reducing temperature by using physical sensible heat carried by the gas, thus obtaining clean and high quality coal tar and gas. The patent provides a method for treating high-temperature oil-containing dust-containing coal gas outside a pyrolysis device, dust removal purification and modification are carried out in a granular bed, the process flow of coal gas treatment is simplified, impurities such as dust and heavy oil generated after purification are difficult to separate after being mixed with a desulfurizing agent, a catalyst and the like, and the regeneration and recycling cost is high. And for the pyrolysis of the mixed coal, the main difficulty lies in that the bed resistance is large, the gas-solid two phases are difficult to uniformly exchange heat, if the structure can be improved in the pyrolysis device, the aims of uniform heat exchange, primary dust fall and gas modification are simultaneously realized, the pressure of a subsequent dust removal working section can be obviously reduced, and the product quality is improved.
201910068284.0 < CN 109679673A Low rank coal pyrolysis furnace and its grading utilization process >, which discloses a low rank coal pyrolysis furnace and its grading utilization process, specifically comprising a furnace body and a plate-type material conveying mechanism arranged along the length direction of the furnace body, wherein the furnace body is a closed heat preservation structure, the upper part of one end is provided with a low rank coal feeding bin, the lower part is provided with a coal ash discharging pipe, the furnace body is internally provided with a drying section, a preheating temperature rise section, a dry distillation section and a cooling section, heat insulation walls are arranged between the sections, a material channel is reserved between the heat insulation walls and the plate-type material conveying mechanism, the furnace body is also provided with a hot carrier gas inlet pipe, a cold gas inlet pipe, a dry gas collecting pipe and a preheating gas collecting pipe, the hot carrier gas inlet pipe is communicated with the dry distillation section, the cold gas inlet pipe is communicated with the cooling section, the dry gas collecting pipe. The method takes a conveying bed as a reaction device, takes high-temperature coal gas as a pyrolysis heat carrier, and solves the problems of non-uniform gas-solid heat exchange and high gas dust content in the coal mixing process, but does not relate to a targeted measure of coal mixing pyrolysis and a purification and modification method of high-dust content pyrolysis coal gas.
201610965775.1 & lt 201610965775.1 & gt CN 106398732A & lt & gt Process and apparatus for low-quality coal poly-generation upgrading relates to a process and apparatus for low-quality coal poly-generation upgrading, which is characterized in that low-quality coal is continuously fed into a dry distillation furnace through a receiving device and a receiving metering device, heating and dry distillation are carried out, after coal gas (including coal tar and moisture) is separated out, clean coal with low volatile content is obtained after remaining solid materials are cooled by a dry quenching device and is continuously fed out, and the dry distillation furnace is provided with a plurality of carbonization chambers, combustion chambers and regenerative chamber burners. The invention adopts an indirect heating method, ensures higher gas quality, and improves the energy efficiency of the system by combining with a regenerative burner. Compared with direct heat exchange, the device for gas-solid indirect heat exchange has lower processing capacity, obvious temperature gradient in the furnace, incomplete reaction of large-particle coal and difficult quality control.
The existing low-rank coal pyrolysis device can be divided into an external heating type and an internal heating type according to a heating mode, and can be divided into a moving bed, a fluidized bed, a rotary furnace and the like according to device types, wherein the internal heating type moving bed pyrolysis device is more and most mature in industrial application due to simple equipment structure and low operation cost. However, when the existing internal heating type moving bed pyrolysis technology is used for treating mixed coal with the particle size less than 30mm, the problems of non-uniform gas-solid heat exchange, low heat utilization efficiency, high gas dust content, difficult purification treatment, easy blockage of equipment pipelines, poor product quality and the like generally exist; the external heating type pyrolysis process has low single-furnace processing capacity due to obvious temperature gradient in the furnace, and is difficult to be applied industrially; the material in the fluidized bed or the rotary furnace pyrolysis device is severely disturbed, the gas dust amount is large, the pyrolysis gas containing dust and oil is separated out in a high-temperature form (400 ℃), the treatment process is complex, the system stability is poor, and the operation cost is high.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a cross-flow type coal mixing pyrolysis method which has the advantages of high heat utilization efficiency, uniform semicoke quality, less dust content in coal gas, low heavy oil content and greatly improved equipment operation stability.
The technical scheme is as follows: the invention relates to a cross-flow type coal mixing pyrolysis method, which is characterized in that raw coal is sequentially treated by a drying section, a dry distillation section and a cooling section, and specifically comprises the following steps:
(1) conveying raw coal into a furnace, exchanging heat with a drying heat source in a drying section, completely removing external water, and increasing the temperature of the obtained material;
(2) under the action of gravity, materials enter a dry distillation section from a drying section, high-temperature coal gas is introduced into a furnace through a multilayer gas distribution structure, the temperature of the materials is gradually increased and pyrolysis reaction is generated after the materials exchange heat, volatile matters are separated out in a gas form, raw coal gas in the furnace is led out of the furnace through a multilayer gas collection structure in the furnace, a tar product is obtained after dust removal and cooling, one part of the gas is used as product coal gas, the other part of the gas enters a heat accumulating type coal gas heating furnace and is heated to be high-temperature coal gas, and the high-temperature coal gas is introduced into the dry distillation section of the pyrolysis furnace through;
(3) and the material continuously descends to the cooling section, the temperature of the hot semicoke is reduced after heat exchange with the circulating cold flue gas, the temperature of the circulating cold flue gas is increased to be changed into circulating hot flue gas, the circulating hot flue gas is led out of the furnace, and the circulating hot flue gas returns to the drying section after dust removal to be used as a drying heat source of the raw coal.
The multilayer gas distribution structure comprises gas distribution pipes which are longitudinally arranged in a multilayer manner, and each layer of gas distribution pipe can release target gas to exchange heat with materials around the gas distribution pipe. The multilayer gas collection structure comprises a gas collection channel and a plurality of gas collection inlets communicated with the gas collection channel, and the gas collection inlets and the multilayer gas distribution pipes are alternately arranged.
Further, a first transition section is arranged between the drying section and the dry distillation section, the dried materials are conveyed to the dry distillation section through the first transition section, the raw coke oven gas obtained after the pyrolysis reaction in the step (2) is guided out to the first transition section through the multilayer gas collection structure, and is guided out of the furnace after being subjected to heat exchange with the materials in the first transition section. The invention adopts a longitudinal multilayer gas distribution and collection structure, gas-solid two-phase cross flow and countercurrent are combined, uniform heat exchange and primary dust fall are realized simultaneously, the dust-containing oil-containing high-temperature coal gas generated by pyrolysis is contacted with a medium-temperature material at a drying and dry distillation transition section for heat exchange, the purpose of secondary dust removal is achieved, a part of heavy tar is condensed and is brought into the dry distillation section by the dry coal for secondary pyrolysis, the coal gas separated out by a pyrolysis device has the characteristics of moderate temperature, low dust content and high light oil content, the working load and equipment investment of a gas purification system are obviously reduced, and the product quality of the coal gas and the tar is improved.
Furthermore, a second transition section is arranged between the dry distillation section and the cooling section, the dry distilled material is conveyed to the cooling section through the second transition section, the circulating hot flue gas which completes heat exchange with the hot semicoke in the step (3) is guided out of the second transition section through the multilayer gas collection structure, and the circulating hot flue gas is guided out of the furnace after heat exchange with the material in the second transition section.
The other part enters a heat accumulating type gas heating furnace to be heated and then is mixed with cold gas to form high-temperature gas. The temperature of the direct combustion may be higher than the temperature required for pyrolysis, and the cold gas has the function of temperature regulation.
Furthermore, the raw coal is low-rank coal, and the method is particularly suitable for the quality-based comprehensive utilization of the low-rank coal or the oil shale such as lignite, long-flame coal and the like. The mixed coal with the grain diameter of less than 30mm can be directly processed.
When the traditional moving bed pyrolysis device is used for treating small-particle coal, the problems of high bed resistance, easy short circuit of gas, non-uniform heat transfer of gas-solid two phases and low heat utilization efficiency exist. The mixed coal contains a certain amount of dust less than 1mm, and has poor mechanical strength, the mixed coal is easy to break to generate a large amount of secondary dust during moving bed movement and heating, the dust content of high-temperature coal gas generated by pyrolysis of the mixed coal is high, high-efficiency dust removal is required before cooling, or tar condensation can cause equipment pipeline blockage. According to the invention, a multilayer gas distribution and collection structure is arranged in a vertical pyrolysis furnace, granular coal is fully pyrolyzed in a thin-layer dry distillation mode, gas-solid cross flow and multi-stage material curtain dust filtration in a pyrolysis section can adjust the gas amount and temperature of a heat carrier according to the difference of material properties, accurate temperature control is realized, the regulation and control are matched with the blanking speed, the dust brought out by the pyrolysis coal gas can be greatly reduced, the pressure of subsequent dust removal equipment is reduced, the sensible heat of the coal gas is recovered, heavy oil which is easy to condense is mixed by the coal material and then enters the pyrolysis section again, the heavy oil is cracked into light components and separated out from the coal gas, the proportion of the light components of tar products is increased, and the economic benefit of the system is also remarkably improved.
The cross-flow type coal mixing pyrolysis device comprises a vertical pyrolysis furnace body, wherein the vertical pyrolysis furnace body comprises a drying unit arranged at the upper section, a pyrolysis unit arranged at the middle section and a cooling unit arranged at the lower section, a multilayer gas distribution structure is arranged at the middle position of the pyrolysis unit and comprises a vertically arranged gas distribution chamber and a plurality of transversely arranged gas distribution branch pipes, each gas distribution branch pipe is communicated with the gas distribution chamber, a multilayer gas collection structure is arranged at the side position of the pyrolysis unit and comprises a gas collection ascending channel arranged close to a furnace wall and a plurality of gas collection umbrellas communicated with the gas collection ascending channel, and the gas collection umbrellas and the gas distribution branch pipes are alternately arranged.
Furthermore, the gas distribution branch pipes are uniformly arranged on the left side and the right side of the gas distribution chamber, the gas distribution branch pipes on each side are arranged in an M x N array, wherein M is larger than 2, the number of layers is represented, N is larger than 2, the number of the gas distribution branch pipes in each layer is represented, the cross section of each gas distribution branch pipe is in an umbrella shape, and gas outlets are formed in the side surfaces of the two ends of each gas distribution umbrella. The cross-flow gas distribution and collection design is adopted, and the gas collection umbrellas and the gas distribution umbrellas are arranged in a staggered manner, so that the height of a bed layer is effectively reduced, the resistance of gas passing through a material layer can be reduced, the gas-solid heat exchange effect is enhanced, meanwhile, the gas generated by pyrolysis is rapidly led out of the furnace, the secondary cracking reaction is avoided, and the tar yield is ensured.
Furthermore, the vertical pyrolysis furnace body also comprises a first transition section arranged between the drying unit and the pyrolysis unit and a second transition section arranged between the pyrolysis unit and the cooling unit, a gas collection ascending channel of the pyrolysis unit penetrates through the pyrolysis unit to the first transition section in the vertical direction, a gas collection ascending channel outlet is arranged at the part of the first transition section of the gas collection ascending channel, and a gas outlet is arranged on the side wall of the first transition section and at the opposite position of the gas collection ascending channel outlet. All gas collected by the gas collection ascending channel passes through a particle bed formed by 150 ℃ dry coal to carry out primary dust fall, the temperature of coal gas is properly reduced, part of heavy oil is mixed with the dry coal after being condensed, the heat of the coal gas is recycled, the aims of primary dust removal and modification are realized, the heavy oil carried by the dry coal is heated and pyrolyzed again in a dry distillation section, light oil and coal gas are generated to be separated out, and the proportion of light oil in a tar product is effectively improved.
Furthermore, the drying unit and the furnace body corresponding to the cooling unit are internally provided with a multilayer gas distribution structure and a multilayer gas collection structure which are the same as those of the pyrolysis unit furnace body.
Furthermore, a gas collection ascending channel of the cooling unit penetrates through the cooling unit to the second transition section in the vertical direction, a gas collection ascending channel outlet is formed in the part, in the second transition section, of the gas collection ascending channel, and a gas outlet is formed in the side wall of the second transition section and in the position, opposite to the gas collection ascending channel outlet, of the second transition section.
The heat carrier gas is led into the furnace from the outside of the furnace through the gas distribution chamber, the gas distribution chamber is divided into a plurality of layers in the longitudinal direction of the furnace body, so that gas-solid phases are uniformly contacted, the gas after heat exchange of each layer enters the gas collection ascending channel through the gas collection umbrella above the gas distribution umbrella, the distance between the gas distribution umbrella and the gas collection umbrella is designed in a pertinence mode according to coal conditions and processing requirements, and the distance between each layer of gas distribution umbrella and each layer of gas collection umbrella is different. The gas collection channel is arranged on the side surface of the outer wall of the pyrolysis furnace, which is beneficial to the deposition and cleaning of dust, the gas entering the gas collection channel rises under the suction action of the fan, enters the furnace again at the transition section, contacts with coal which is not heated, and the dust and heavy oil are deposited at the transition section, thus achieving the purpose of primary dust removal and modification. The modified coal gas is collected to a gas outlet through a gas collecting umbrella at the upper part of the gas distribution umbrella and is led out of the furnace. The gas distribution chamber is connected with a fan of the heat supply system, a gas outlet is connected with a draught fan, and the gas distribution chamber and the draught fan jointly realize gas drainage.
Has the advantages that: compared with the prior art, the invention has the following advantages: (1) the invention adopts a unique gas collection and distribution mode, solves the problem of realizing the pyrolysis of the coal-mixed moving bed in a gas-solid direct heat exchange mode, and has the advantages of simple process flow and controllable operation compared with the fluidized bed pyrolysis technology; compared with a vertical furnace with indirect heat exchange and other pyrolysis devices, the device has the advantages of high heat utilization efficiency, uniform semicoke quality, low dust content in coal gas, low heavy oil content and greatly improved operation stability; (2) the pyrolysis device has the advantages that through the multilayer gas distribution and collection structure, the treatment capacity of the pyrolysis device is obviously improved, the structure is compact, the occupied area is small, the process flow is reliable, the heat utilization efficiency is high, and the operation cost is low. The indirect heating type pyrolysis furnace, the conveying bed pyrolysis device and the fluidized bed device are difficult to realize; (3) according to the invention, the gas distribution and the gas collection chamber are arranged in the furnace at intervals in a staggered manner, so that the flow guide and gas introduction route is simpler, the bed resistance is reduced, and the effect of uniform heat exchange is achieved; (4) compared with the integrated technology of desulfurization, dust removal and modification of coal gas outside the furnace, the invention solves the problem of mixed coal pyrolysis through the structural improvement of the pyrolysis device, so that the coal gas simultaneously realizes the aims of uniform heat exchange, primary dust fall and gas modification in the furnace, the pressure of a subsequent dust removal section can be obviously reduced, and the product quality is improved.
Drawings
FIG. 1 is a flow diagram of a cross-flow coal-blending pyrolysis process;
FIG. 2 is a schematic view of the internal structure of the dry distillation section;
FIG. 3 is a perspective view of a multilayer air distribution structure in example 2;
FIG. 4 is a front view of a multilayer air distribution structure in example 2;
FIG. 5 is a left side view of the multilayer air distribution structure of example 2;
FIG. 6 is a schematic view of an air distribution umbrella;
figure 7 is a schematic view of a gas collection umbrella.
Detailed Description
For a further understanding of the present invention, reference will now be made in detail to the embodiments illustrated in the drawings.
Example 1
In this embodiment, long flame coal pyrolysis is taken as an example, as shown in fig. 1, raw materials can directly enter a furnace through a conveying belt, heat exchange is carried out between the raw materials and hot flue gas in a drying section, external water is completely removed, and the temperature of the materials is raised to about 200 ℃. Under the action of gravity, the material enters a dry distillation section and exchanges heat with 850 ℃ coal gas. In order to reduce the resistance of gas passing through materials and increase the gas retention time, high-temperature coal gas is introduced into the furnace layer by layer through a multilayer gas inlet structure, the temperature of the materials is gradually increased to 600 ℃ and pyrolysis reaction is generated, volatile matters are separated out in a gas form and are led out of the furnace after being integrated through a multilayer gas collection structure in the furnace, and the temperature of a gas outlet is about 300 ℃. And the material after the dry distillation reaction continuously descends to a cooling section, the temperature of the hot semicoke is reduced to be below 100 ℃ after heat exchange with the circulating cold flue gas, the temperature of the flue gas is increased to 300 ℃, and the hot semicoke returns to a drying section after dust removal to be used as a drying heat source of the raw coal. The heat load of the carbonization section can be reduced by pre-drying the raw coal, most of drying heat sources come from the sensible heat of materials in the cooling section, and if the moisture of the raw coal is high, a part of hot flue gas can be supplemented through a combustion system.
The raw gas generated in the dry distillation section is dedusted and cooled to obtain a tar product, part of the gas is used as product gas, the gas is completely generated in the pyrolysis process, the ratio of effective components is high, and the tar product can be used as synthesis gas or used for preparing LNG. The other part of the coke enters a heat accumulating type coal gas heating furnace to be heated to 1000 ℃, then is mixed with cold coal gas to 850 ℃, and is guided into a dry distillation section of the pyrolysis furnace through a multilayer gas distribution structure, and under the atmosphere, the coal gas not only serves as a heat transfer medium, but also has a promoting effect on a pyrolysis reaction process and tar generation, so that the tar yield is improved.
Example 2
The cross-flow coal mixing pyrolysis device described in this embodiment, as shown in fig. 2-7, includes a vertical pyrolysis furnace body, the vertical pyrolysis furnace body 1 includes inside a drying unit, a first transition section 8, a pyrolysis unit 1, a second transition section and a cooling unit that are sequentially arranged from top to bottom, a multilayer gas distribution structure is arranged at a middle position of the pyrolysis unit, the multilayer gas distribution structure includes a vertically arranged gas distribution chamber 2 and a plurality of transversely arranged gas distribution branch pipes 3, a gas inlet 6 is arranged on the gas distribution chamber, each gas distribution branch pipe is communicated with the gas distribution chamber, the gas distribution branch pipes 3 are uniformly arranged at left and right sides of the gas distribution chamber 2, the gas distribution branch pipes at each side are arranged in a 13 x 6 array, a cross section of each gas distribution branch pipe is in a gas distribution umbrella shape 11, and gas outlets 12 are arranged on side surfaces of two ends of the gas distribution umbrella 11. The side position of the pyrolysis unit is provided with a multilayer gas collection structure, the multilayer gas collection structure comprises a gas collection ascending channel 4 arranged close to the furnace wall and a plurality of gas collection umbrellas 5 communicated with the gas collection ascending channel, and the gas collection umbrellas and the gas distribution branch pipes are arranged at intervals and alternately. The drying unit and the furnace body corresponding to the cooling unit are internally provided with a multilayer gas distribution structure and a multilayer gas collection structure which are the same as those of the pyrolysis unit furnace body.
The first transition section is arranged between the drying unit and the pyrolysis unit, the second transition section is arranged between the pyrolysis unit and the cooling unit, a gas collection ascending channel 4 of the pyrolysis unit penetrates through the pyrolysis unit to the first transition section in the vertical direction, a gas collection ascending channel outlet 7 is arranged on the part of the first transition section of the gas collection ascending channel, dust 10 is deposited at the bottom of the gas collection ascending channel, and a gas outlet 9 is arranged on the side wall of the first transition section and at the opposite position of the gas collection ascending channel outlet. The gas collection ascending channel of the cooling unit penetrates through the cooling unit to the second transition section in the vertical direction, a gas collection ascending channel outlet is formed in the part, in the second transition section, of the gas collection ascending channel, and a gas outlet is formed in the side wall of the second transition section and in the position, opposite to the gas collection ascending channel outlet, of the second transition section.
The cross-flow coal-mixing pyrolysis device described in this embodiment sequentially comprises a drying unit, a pyrolysis unit and a cooling unit from top to bottom, a transition section is arranged between adjacent units, and a plurality of longitudinally-arranged gas distribution and collection structures are arranged in each unit. Taking the pyrolysis unit as an example, high-temperature gas (flue gas or coal gas at about 850 ℃) generated by a burner or a regenerative furnace is introduced into the furnace from a gas distribution pipe and a gas distribution umbrella, the gas in the umbrella flows out laterally, after cross-flow heat exchange with materials in the furnace, the high-temperature gas and the oil gas generated by pyrolysis enter a longitudinal gas collecting pipe from an inlet 13 of the gas collecting umbrella, and at the top of a longitudinal gas collecting channel, secondary heat exchange is carried out with the materials in a transition section, at the moment, the temperature of the coal gas is reduced from 300 ℃ to about 150 ℃, and partial heavy oil in the coal gas is condensed and then enters the pyrolysis unit together with the materials to generate secondary pyrolysis. The dust content in the gas separated out from the transition section is greatly reduced, and the gas is primarily purified and modified. The heat exchange of the gas phase and the solid phase is in a counter-flow and cross-flow type from the gas distribution umbrella to the gas collection umbrella, and in a transition section, the heat exchange is in a cross-flow type. The drying unit and the cooling unit exchange heat in a similar manner as the pyrolysis unit. Wherein the heat source of the drying unit mainly comes from the waste heat recovered by the semicoke in the cooling section, and the specific flow is as follows: and after dedusting and spraying, the flue gas subjected to heat exchange in the drying unit is introduced into a cooling section to exchange heat with high-temperature semicoke to about 300 ℃, and then introduced into the drying unit to serve as a heat carrier, so that dry quenching of the flue gas is realized. If the moisture content of the raw material is low (< 5%), the drying unit and the pyrolysis unit can be directly combined, and the separation position of the coal gas of the pyrolysis unit can be adjusted.
The temperature of the materials in the furnace is raised to 150 ℃ after passing through the drying unit, the moisture is reduced to below 1 percent, the materials are contacted with coal gas with the temperature of about 300 ℃ from the gas collecting pipe, the temperature of the materials is raised to 200 ℃,
according to the cross-flow moving bed provided by the invention, the heat source of the pyrolysis section is high-temperature gas (flue gas or coal gas), the gas inlets are arranged in a multilayer manner to adapt to the characteristics of raw materials, the outer wall of the furnace is provided with the independent gas inlet chamber for introducing the high-temperature heat carrier into the furnace, the pressure in the furnace is self-balanced, the temperature of each layer of inlets can be flexibly adjusted through gas distribution, the accurate temperature control is realized, and the heat utilization efficiency is higher. The raw gas outlet is also arranged on the outer wall of the furnace, so that the flue can be cleaned without stopping the furnace, and the running time of the system is effectively prolonged. If the processing capacity of a single furnace needs to be improved, the cross section area of the furnace body and the gas distribution and collection chambers can be increased, and the device has a compact structure.
Claims (10)
1. A cross-flow type coal mixing pyrolysis method is characterized in that raw coal is sequentially processed by a drying section, a dry distillation section and a cooling section, and the method specifically comprises the following steps:
(1) conveying raw coal into a furnace, exchanging heat with a drying heat source in a drying section, completely removing external water, and increasing the temperature of the obtained material;
(2) under the action of gravity, materials enter a dry distillation section from a drying section, high-temperature coal gas is introduced into a furnace through a multilayer gas distribution structure, the temperature of the materials is gradually increased and pyrolysis reaction is generated after the materials exchange heat, volatile matters are separated out in a gas form, raw coal gas in the furnace is led out of the furnace through a multilayer gas collection structure in the furnace, a tar product is obtained after dust removal and cooling, one part of the gas is used as product coal gas, the other part of the gas enters a heat accumulating type coal gas heating furnace and is heated to be high-temperature coal gas, and the high-temperature coal gas is introduced into the dry distillation section of the pyrolysis furnace through;
(3) and the material continuously descends to the cooling section, the temperature of the hot semicoke is reduced after heat exchange with the circulating cold flue gas, the temperature of the circulating cold flue gas is increased to be changed into circulating hot flue gas, the circulating hot flue gas is led out of the furnace, and the circulating hot flue gas returns to the drying section after dust removal to be used as a drying heat source of the raw coal.
2. The cross-flow type coal mixing pyrolysis method according to claim 1, wherein a first transition section is arranged between the drying section and the dry distillation section, the dried material passes from the first transition section to the dry distillation section, the raw coke oven gas obtained after the pyrolysis reaction in the step (2) is led out to the first transition section through a multi-layer gas collection structure, and is led out of the oven after being subjected to heat exchange with the material in the first transition section.
3. The cross-flow coal-mixing pyrolysis method according to claim 1, wherein a second transition section is arranged between the dry distillation section and the cooling section, the dry-distilled material passes through the second transition section to the cooling section, the circulating hot flue gas which completes heat exchange with the hot semicoke in the step (3) is led out to the second transition section through the multilayer gas collection structure, and the circulating hot flue gas is led out of the furnace after heat exchange with the material in the second transition section.
4. The cross-flow coal blending pyrolysis method of claim 1, wherein the raw coal is low rank coal.
5. The cross-flow coal mixing pyrolysis method of claim 1, wherein the other part in step (2) enters a regenerative gas heating furnace to be heated, and then is mixed with cold gas to form high-temperature gas.
6. A cross-flow coal-mixed pyrolysis device suitable for the pyrolysis method of claims 1 to 5, comprising a vertical pyrolysis furnace body, the interior of the vertical pyrolysis furnace body comprises a drying unit arranged at the upper section, a pyrolysis unit arranged at the middle section and a cooling unit arranged at the lower section, it is characterized in that a multi-layer gas distribution structure is arranged in the middle of the pyrolysis unit (1), the multilayer gas distribution structure comprises a vertically arranged gas distribution chamber (2) and a plurality of transversely arranged gas distribution branch pipes (3), each gas distribution branch pipe is communicated with the gas distribution chamber, the side position of the pyrolysis unit is provided with a multilayer gas collection structure, the multilayer gas collection structure comprises a gas collection ascending channel (4) close to the furnace wall and a plurality of gas collection umbrellas (5) communicated with the gas collection ascending channel, and the gas collection umbrellas and the gas distribution branch pipes are alternately arranged.
7. A cross-flow type coal mixing pyrolysis device according to claim 6, wherein the gas distribution branch pipes are uniformly arranged at the left side and the right side of the gas distribution chamber, the gas distribution branch pipes at each side are arranged in an M x N array, wherein M is more than 2 and represents the number of layers, N is more than 2 and represents the number of the gas distribution branch pipes in each layer, the cross section of each gas distribution branch pipe is in the shape of a gas distribution umbrella (11), and the side surfaces of two ends of each gas distribution umbrella are provided with gas outlets (12).
8. The cross-flow type coal-mixing pyrolysis device according to claim 6, wherein the vertical pyrolysis furnace body further comprises a first transition section (8) arranged between the drying unit and the pyrolysis unit, and a second transition section arranged between the pyrolysis unit and the cooling unit, a gas collection ascending channel of the pyrolysis unit vertically penetrates through the pyrolysis unit to the first transition section, a gas collection ascending channel outlet (7) is arranged on the part of the first transition section of the gas collection ascending channel, a gas outlet (9) is arranged on the side wall of the first transition section and in the position opposite to the gas collection ascending channel outlet, the gas distribution chamber is connected with a fan of a heat supply system, and the gas outlet is connected with an induced draft fan.
9. The cross-flow type coal-mixing pyrolysis device as claimed in claim 6, wherein the drying unit and the cooling unit are provided with a multi-layer gas distribution structure and a multi-layer gas collection structure inside the furnace body, which are the same as those inside the pyrolysis unit.
10. The cross-flow coal-mixing pyrolysis device as claimed in claim 6, wherein the gas-collecting ascending channel of the cooling unit penetrates through the cooling unit to the second transition section in the vertical direction, the gas-collecting ascending channel is provided with a gas-collecting ascending channel outlet at a part of the second transition section, and a gas outlet is provided on the side wall of the second transition section at a position opposite to the gas-collecting ascending channel outlet.
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| CN114907870A (en) * | 2022-05-16 | 2022-08-16 | 延安大学 | Quality improving method for caking coal washing and pyrolysis reactor |
| CN115305104A (en) * | 2022-03-04 | 2022-11-08 | 陕西东鑫垣化工有限责任公司 | Semi coke drying and rotary kiln secondary pyrolysis purification process |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN204237743U (en) * | 2014-10-28 | 2015-04-01 | 北京国电富通科技发展有限责任公司 | A kind of New type coal gas retort |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN204237743U (en) * | 2014-10-28 | 2015-04-01 | 北京国电富通科技发展有限责任公司 | A kind of New type coal gas retort |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115305104A (en) * | 2022-03-04 | 2022-11-08 | 陕西东鑫垣化工有限责任公司 | Semi coke drying and rotary kiln secondary pyrolysis purification process |
| CN115305104B (en) * | 2022-03-04 | 2023-12-05 | 陕西东鑫垣化工有限责任公司 | Semi-coke drying and rotary kiln secondary pyrolysis purification process |
| CN114907870A (en) * | 2022-05-16 | 2022-08-16 | 延安大学 | Quality improving method for caking coal washing and pyrolysis reactor |
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