CN116443879B - Calcium carbide production method and production system - Google Patents
Calcium carbide production method and production system Download PDFInfo
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- CN116443879B CN116443879B CN202310727337.1A CN202310727337A CN116443879B CN 116443879 B CN116443879 B CN 116443879B CN 202310727337 A CN202310727337 A CN 202310727337A CN 116443879 B CN116443879 B CN 116443879B
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- 239000005997 Calcium carbide Substances 0.000 title claims abstract description 184
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 title claims abstract description 184
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 126
- 238000000197 pyrolysis Methods 0.000 claims abstract description 219
- 239000007789 gas Substances 0.000 claims abstract description 163
- 239000008188 pellet Substances 0.000 claims abstract description 154
- 238000006243 chemical reaction Methods 0.000 claims abstract description 55
- 239000003245 coal Substances 0.000 claims abstract description 44
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 37
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 37
- 239000004571 lime Substances 0.000 claims abstract description 37
- 238000002156 mixing Methods 0.000 claims abstract description 28
- 238000002844 melting Methods 0.000 claims abstract description 26
- 230000008018 melting Effects 0.000 claims abstract description 26
- 239000003034 coal gas Substances 0.000 claims abstract description 22
- 239000002994 raw material Substances 0.000 claims abstract description 20
- 238000000465 moulding Methods 0.000 claims abstract description 19
- 238000001816 cooling Methods 0.000 claims abstract description 13
- 239000011230 binding agent Substances 0.000 claims abstract description 12
- 239000007788 liquid Substances 0.000 claims abstract description 11
- 238000003825 pressing Methods 0.000 claims abstract 2
- 239000000463 material Substances 0.000 claims description 78
- 239000000203 mixture Substances 0.000 claims description 28
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 19
- 239000003546 flue gas Substances 0.000 claims description 19
- 238000002485 combustion reaction Methods 0.000 claims description 16
- 239000002245 particle Substances 0.000 claims description 7
- 239000003232 water-soluble binding agent Substances 0.000 claims description 6
- 229920001800 Shellac Polymers 0.000 claims description 5
- 238000010298 pulverizing process Methods 0.000 claims description 5
- 239000004208 shellac Substances 0.000 claims description 5
- ZLGIYFNHBLSMPS-ATJNOEHPSA-N shellac Chemical group OCCCCCC(O)C(O)CCCCCCCC(O)=O.C1C23[C@H](C(O)=O)CCC2[C@](C)(CO)[C@@H]1C(C(O)=O)=C[C@@H]3O ZLGIYFNHBLSMPS-ATJNOEHPSA-N 0.000 claims description 5
- 229940113147 shellac Drugs 0.000 claims description 5
- 235000013874 shellac Nutrition 0.000 claims description 5
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 4
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- 238000000227 grinding Methods 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 4
- 239000002904 solvent Substances 0.000 claims description 4
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims description 3
- 239000004375 Dextrin Substances 0.000 claims description 3
- 229920001353 Dextrin Polymers 0.000 claims description 3
- 229920002472 Starch Polymers 0.000 claims description 3
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 3
- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims description 3
- 239000008112 carboxymethyl-cellulose Substances 0.000 claims description 3
- 235000019425 dextrin Nutrition 0.000 claims description 3
- 235000019422 polyvinyl alcohol Nutrition 0.000 claims description 3
- 239000008107 starch Substances 0.000 claims description 3
- 235000019698 starch Nutrition 0.000 claims description 3
- 239000003021 water soluble solvent Substances 0.000 claims description 2
- 239000000853 adhesive Substances 0.000 claims 1
- 230000001070 adhesive effect Effects 0.000 claims 1
- 238000000034 method Methods 0.000 abstract description 63
- 239000000571 coke Substances 0.000 abstract description 36
- 238000005265 energy consumption Methods 0.000 abstract description 7
- 239000000126 substance Substances 0.000 abstract description 2
- 239000012495 reaction gas Substances 0.000 abstract 1
- 239000002918 waste heat Substances 0.000 description 36
- 238000011084 recovery Methods 0.000 description 31
- 239000000428 dust Substances 0.000 description 15
- 239000000843 powder Substances 0.000 description 14
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 13
- 239000011269 tar Substances 0.000 description 11
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- 230000035484 reaction time Effects 0.000 description 8
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- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000002817 coal dust Substances 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 238000010309 melting process Methods 0.000 description 3
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- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000012946 outsourcing Methods 0.000 description 2
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- 229910001018 Cast iron Inorganic materials 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 239000011280 coal tar Substances 0.000 description 1
- 238000004939 coking Methods 0.000 description 1
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/90—Carbides
- C01B32/914—Carbides of single elements
- C01B32/942—Calcium carbide
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
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Abstract
The invention belongs to the technical field of chemical industry, and relates to a calcium carbide production method and a calcium carbide production system. The production method comprises the following steps: (1) Mixing the crushed raw material lime with coal in the presence of a binder, and then cold-pressing and molding to obtain pellets; (2) preheating and pyrolyzing the pellets in sequence; (3) And carrying out high-temperature melting reaction on the pyrolyzed pellets obtained by the pyrolysis reaction to generate liquid calcium carbide, and cooling and crushing the discharged liquid calcium carbide to form finished calcium carbide, wherein the preheating is realized by mixing and contacting the pellets with pyrolysis gas generated by the pyrolysis reaction and coal gas generated by the high-temperature melting reaction. According to the invention, the mixed pellets of the pulverized coal and the lime can be directly used as raw materials, and the two steps of the process of producing the coke by pyrolyzing the pulverized coal and the process of producing the calcium carbide by mixing the coke and the lime are combined into one step to produce the calcium carbide in the calcium carbide furnace, so that the energy consumption and the production cost in the calcium carbide production process are reduced.
Description
Technical Field
The invention belongs to the technical field of chemical industry, and relates to a calcium carbide production method and a calcium carbide production system.
Background
Calcium carbide is an important raw material for preparing acetylene, and acetylene prepared from the calcium carbide is widely applied to metal welding and cutting. The traditional calcium carbide preparation process mainly adopts low ash content and low volatile coke (or semi-coke) and quicklime as raw materials, and carries out melting reaction in an electric furnace to prepare the calcium carbide. The specific process flow of the preparation process is as shown in figure 1: the calcined lime in the lime kiln is sent to a lime bin of a batching station for storage for standby through a belt conveyor after being screened (or outsourcing qualified finished lime); drying and screening outsourcing coke (or semi-coke) with qualified granularity, and then entering a coke bin of a batching station for storage for later use; in a batching station, the blocky quicklime and coke (or semi-coke) are respectively weighed and batched according to the proportion specified by the process, the furnace burden is conveyed to the furnace top of an electric furnace after being mixed by a belt conveyor, and the furnace top feeder and a storage bin are used for sequentially feeding the furnace; charging materials enter a calcium carbide furnace from a material pipe to generate high-temperature melting chemical reaction to generate calcium carbide; and cooling and crushing the calcium carbide after the calcium carbide is discharged from the furnace to obtain the finished product calcium carbide.
The raw material feeding mode of the process flow is as follows: the mixed materials which are uniformly metered and mixed are conveyed to a material shortage bin through an annular material distributor, a material pipe inserted into a furnace cover is arranged below the bin, and the mixed materials are uniformly put into the calcium carbide furnace through the material pipe.
In the process flow, as the calcium carbide reaction in the furnace proceeds, the calcium carbide liquid in the calcium carbide furnace molten pool is discharged periodically, and when the material level in the calcium carbide furnace descends, the mixture in the material pipe immediately enters the reaction material layer in the furnace, and the mixture in the material shortage bin falls and is supplemented. The material shortage bin sets high, low and low material levels, and when a low material level signal appears, batch charging of the bin is started; the feeding is stopped when the level reaches a high level (or batch is completed). The low material level signal is used as a danger alarm to prompt an operator that the material shortage of the material bin reaches a warning line.
In the above process flow, lump coal is generally used for pyrolysis to produce coke (or semi-coke), and then the coke (or semi-coke) and quicklime are mixed for high-temperature melting reaction to produce calcium carbide, that is, the conventional calcium carbide production process cannot realize the continuity of the whole system production process from raw coal.
Disclosure of Invention
The invention aims to provide a calcium carbide production method, which can directly adopt mixed pellets of coal dust and lime as raw materials, organically combine the process of producing coke by pyrolyzing the coal dust and the process of producing calcium carbide by mixing the coke and the lime, and organically use heat energy generated by pyrolysis reaction and calcium carbide production for preheating the pellets, thereby reducing the energy consumption of the calcium carbide production process and simultaneously reducing the production cost.
To achieve the object, in a basic embodiment, the present invention provides a method for producing calcium carbide, the method comprising the steps of:
(1) Mixing raw lime and coal after crushing and pulverizing in the presence of a binder, and then performing cold press molding to obtain pellets, wherein the strength of the pellets meets the breakage rate after falling for 5 times at a height of 2 meters, namely, the number proportion of the crushed particles smaller than 5 millimeters to all the pellets is not more than 3 percent;
(2) Preheating and pyrolyzing the pellets successively;
(3) Carrying out high-temperature melting reaction on the pyrolyzed pellets obtained by the pyrolysis reaction to generate liquid calcium carbide, cooling and crushing the discharged liquid calcium carbide to form finished product calcium carbide, wherein the temperature of the high-temperature melting reaction is 1800-2200 ℃;
wherein the preheating is achieved by contacting the pellets with a mixture of pyrolysis gas produced by the pyrolysis reaction and gas produced by the high temperature melting reaction.
In a preferred embodiment, the invention provides a method for producing calcium carbide, wherein the contacting is for 1-3min.
In a preferred embodiment, the present invention provides a method for producing calcium carbide, wherein in step (2), the preheating is to 200-300 ℃.
In a preferred embodiment, the present invention provides a method for producing calcium carbide, wherein in step (1),
the binder is selected from one or more of water-soluble binders and/or solvent binders;
the water-soluble binder is one or more selected from starch, dextrin, polyvinyl alcohol and carboxymethyl cellulose;
the solvent-based binder is selected from shellac and/or butyl rubber.
In a preferred embodiment, the invention provides a method for producing calcium carbide, wherein in the step (1), the crushing and pulverizing is that the average particle size of raw lime and coal is crushed to 100-200nm. For example, the pulverization and pulverization can be performed by a mill.
In a preferred embodiment, the invention provides a calcium carbide production method, wherein in the step (1), the mixing mass ratio of raw lime to coal is 1:1.2-1.5.
In a preferred embodiment, the present invention provides a method for producing calcium carbide, wherein the temperature of the pyrolysis reaction can be 450-700 ℃; the pyrolysis reaction time can be 3-30min or 0.5-2h.
In a preferred embodiment, the invention provides a method for producing calcium carbide, wherein in the step (3), the time of the high-temperature melting reaction is 30-120min.
A second object of the present invention is to provide a calcium carbide production system for implementing the aforementioned production method, so as to better implement the aforementioned production method, thereby reducing energy consumption and production cost in the calcium carbide production process.
In order to achieve the aim, in a basic embodiment, the invention provides a calcium carbide production system for realizing the production method, wherein the production system comprises a crushing device, a cold press molding bin, a preheating bin, a pyrolysis furnace, a calcium carbide furnace and a mixing chamber which are connected in sequence;
the crushing device is used for crushing raw lime and coal;
the cold press molding bin is used for storing the pellets after cold press molding;
the preheating bin is used for preheating the pellets;
the pyrolysis furnace is used for carrying out pyrolysis reaction of the pellets;
the calcium carbide furnace is used for carrying out high-temperature melting reaction of the pyrolyzed pellets;
the preheating bin, the pyrolysis furnace and the calcium carbide furnace are communicated through the mixing chamber, so that pyrolysis gas generated in the pyrolysis furnace and coal gas generated in the calcium carbide furnace are mixed in the mixing chamber and then introduced into the preheating bin.
In a preferred embodiment, the present invention provides a calcium carbide production system for realizing the aforementioned production method, wherein:
an air inlet branch pipe, a material channel and an air outlet main pipe are arranged in the preheating bin, the air inlet branch pipe is positioned at the lower section of the preheating bin, the air outlet main pipe is positioned at the upper section of the preheating bin, and the material channel is arranged in the inner cavity of the preheating bin;
the material channel is characterized in that a louver board is arranged on the side wall in the material channel, one end of the louver board is fixed on the side wall of the material channel, and the other end of the louver board is used as a free end to extend to the inner cavity of the material channel and incline downwards.
In a preferred embodiment, the invention provides a calcium carbide production system for realizing the production method, wherein the material channel is provided with a plurality of layers along the vertical direction, each layer is provided with a plurality of shutter plates, and the included angle alpha between each shutter plate and the material channel in the vertical direction is 15-25 degrees.
In a preferred embodiment, the invention provides a calcium carbide production system for realizing the production method, wherein the production system further comprises one or more components of a combustion chamber, a pyrolysis pellet bin and a calcium carbide pot,
the combustion chamber is connected with the pyrolysis furnace, so that flue gas generated in the combustion chamber is introduced into the pyrolysis furnace and used for heating to carry out pyrolysis reaction;
the pyrolysis pellet bin is connected with the pyrolysis furnace and the calcium carbide furnace and is used for storing pyrolysis pellets obtained after pyrolysis reaction;
the calcium carbide pot is connected with the calcium carbide furnace, and liquid calcium carbide is led out and enters the calcium carbide pot.
In a preferred embodiment, the invention provides a calcium carbide production system for realizing the production method, wherein a gas channel is arranged at the periphery of the material channel, an air inlet hole is arranged on the side wall of the material channel, and the gas channel and the material channel are in gas communication through the air inlet hole.
In a preferred embodiment, a plurality of gas channel separators are arranged on each gas channel and used for changing the flow direction of gas in the gas channel and enhancing the gas waste heat exchange effect and the purification effect, one or a plurality of air inlet holes are arranged between every two adjacent gas channel separators, and the aperture or equivalent diameter of each air inlet hole is smaller than the grain diameter of the calcium carbide raw material.
The method and the system for producing the calcium carbide have the beneficial effects that the mixed pellets of the pulverized coal and the lime can be directly used as raw materials, and the two steps of the process of producing the coke by pyrolyzing the pulverized coal and the process of producing the calcium carbide by mixing the pulverized coal and the coke and the lime are organically combined, so that the thermal energy generated by the pyrolysis reaction and the production of the calcium carbide is organically used for preheating the pellets, thereby reducing the energy consumption of the production process of the calcium carbide and simultaneously reducing the production cost.
The beneficial effects of the invention are as follows:
(1) The invention realizes the continuity from raw coal to the whole process of calcium carbide production, and omits a separate coking step in the traditional calcium carbide production process.
(2) The invention uses the pyrolysis gas generated in the coal pyrolysis process and the coal gas generated in the high-temperature melting process of the calcium carbide to exchange heat for the pellets, thereby overcoming the defect that the waste heat of the coal gas is not fully utilized in the traditional calcium carbide production process. Meanwhile, in order to realize higher-efficiency heat exchange, the invention uses the preheating bin with a specific design, so that the residence time of the pellets in the preheating bin is longer, and the full heat exchange is realized. The temperature difference between the mixture entering the preheating bin and the mixture exiting the preheating bin can reach 1400-1700 ℃, so that higher heat exchange efficiency is realized.
(3) According to the invention, the louver components are arranged in the preheating bin, and under the interference of the louvers in specific arrangement, the mixed gas does not linearly rise in the preheating bin but rises in a baffling way, so that the turbulence degree of the mixed gas in the preheating bin is increased, and the heat exchange probability of the mixed gas and the pellets is improved.
(4) According to the invention, the pyrolysis pellets generated by the pyrolysis reaction directly enter the pyrolysis pellet bin to serve as the raw material of the calcium carbide furnace, so that the hot coke powder quenching procedure after coal pyrolysis and coke making in the traditional calcium carbide production process is omitted, and the heat loss in the quenching process is avoided.
(5) The calcium carbide production method is suitable for various pyrolysis furnace types including spiral pyrolysis furnaces, fluidized pyrolysis furnaces, rotary pyrolysis furnaces and mobile pyrolysis furnaces, and realizes the coupling of the traditional coal pyrolysis process and the calcium carbide production process.
In conclusion, the method reduces the energy consumption and the production cost in the calcium carbide production process.
Drawings
FIG. 1 is a process flow diagram of a prior art calcium carbide production process.
Fig. 2 is a process flow diagram of an exemplary calcium carbide production method of the present invention.
Fig. 3 is a spiral pyrolysis process and corresponding production system.
Fig. 4 is a fluidized pyrolysis process and corresponding production system.
Fig. 5 is a rotary pyrolysis process and corresponding production system.
Fig. 6 is a mobile pyrolysis process and corresponding production system.
FIG. 7 is an exemplary block diagram of a pyrolysis furnace corresponding to each of the pyrolysis processes of FIGS. 3-6, wherein a is a pyrolysis furnace corresponding to a spiral pyrolysis process; b is a pyrolysis furnace corresponding to a fluidized pyrolysis process; c is a pyrolysis furnace corresponding to a rotary pyrolysis process; d is a pyrolysis furnace corresponding to the movable pyrolysis process.
Fig. 8 is a schematic diagram of the pellet preheating principle of the present invention.
Fig. 9 is a block diagram of the preheating silo of fig. 3-6.
Fig. 10 is a horizontal sectional view of the intake hole of fig. 9.
Fig. 11 is a cross-sectional view of fig. 9 taken along line II-II.
Detailed Description
The following describes the embodiments of the present invention further with reference to examples and drawings.
The traditional calcium carbide production method is to adopt cooling coke (or semi-coke) generated in the raw coal pyrolysis process and lime to perform cold press molding to form pellets, then preheating the pellets, and performing a melting reaction in a calcium carbide furnace, wherein the heat exchange process is to utilize coal gas generated in the melting reaction to perform heat exchange with the pellets. That is, in the conventional calcium carbide production method, the carbon source used is cold coke formed after pyrolysis of raw coal, and the heat generated by pyrolysis of raw coal is not used in the calcium carbide production process at all.
Compared with the traditional production method, the calcium carbide production method of the invention mainly has the following differences: in the production method, the pyrolysis process and the calcium carbide production process are organically combined, and raw coal can be directly used as a carbon source; simultaneously, the two processes are organically combined in the following way: and combining pyrolysis gas generated by the pyrolysis reaction and high-temperature gas generated in the calcium carbide production process to preheat the pellets before pyrolysis. By adopting the combination mode, the heat released by cooling the high-temperature coke generated by pyrolysis of raw coal in the traditional method is recycled for calcium carbide production, and the heat generated by high-temperature coal gas generated by pyrolysis is also recycled for calcium carbide production, so that the recovery rate of waste heat is greatly improved.
In order to adapt to the organic combination of the pyrolysis process and the calcium carbide production process, the calcium carbide production system provided by the invention is provided with the mixing chamber for mixing pyrolysis gas and high-temperature gas in the mixing chamber, and the formed mixed gas flows into the preheating bin for preheating the pellets.
The calcium carbide production method and the system thereof greatly improve the utilization rate of waste heat, and greatly save the heat supply cost for industrial and continuous production of calcium carbide.
In addition, in one embodiment of the invention, the preheating bin is adopted to preheat the pellets, so that the residence time of the pellets in the preheating bin can be prolonged, and the heat exchange time of the pellets and the mixed gas can be prolonged, thereby enabling the heat exchange amount of the mixed gas in the preheating bin to be higher. In one embodiment, the temperature of the pellets after preheating is in the range of 200-300 ℃. The temperature difference of the mixed gas before and after heat exchange can reach 1400-1700 ℃, and the utilization rate of the residual heat is further improved.
Regarding the calculation of the residual heat utilization rate, the present invention performs the following rough calculation.
The temperature of the gas generated by the calcium carbide production method is generally within the range of 1800-2200 ℃ (calculated at 2000 ℃). In the traditional calcium carbide production method, after heat exchange is carried out on high-temperature coal gas and pellets, the outlet temperature of the coal gas after heat exchange is within 400-600 ℃ (calculated at 500 ℃);
waste heat recovery rate=waste heat recovery heat of gas produced by calcium carbide production/sensible heat of gas produced by calcium carbide production x 100%.
In the production method of the invention, the raw coal pyrolysis process and the calcium carbide production process are organically combined together, and the recycled waste heat comprises: the heat released by cooling the hot coke generated by pyrolysis and the heat generated by pyrolysis gas in the traditional production method are both recycled in the calcium carbide production process (the two heat are used for preheating pellets by forming a mixed gas in the invention).
The production method has the advantages that the waste heat recovery rate= (waste heat recovery heat of gas produced by calcium carbide, pyrolysis gas recycling heat in pyrolysis process, coke recycling heat in pyrolysis process-quick lime needs to provide heat in a pyrolysis furnace)/sensible heat of gas produced by calcium carbide production is multiplied by 100 percent
Because the waste heat recovery rate of the traditional production method is the same as the waste heat recovery rate calculation time denominator of the production method, the waste heat recovery rate of the traditional production method can be compared with the waste heat recovery rate of the production method only by using a molecular calculation result, namely the calculation result of the waste heat recovery amount.
The rough calculation process of the waste heat recovery amount is as follows:
according to the application of the semi-coke in the fields of calcium carbide production, special alloy smelting and blast furnace injection in the literature, the semi-coke is mainly produced by using raw coal (long flame coal, non-caking coal, weak caking coal and the like), 1 ton of semi-coke is produced with the average consumption of 1.6-1.7 tons of raw coal, and meanwhile, about 0.1-0.16 ton of coal tar and 900-1500m of byproduct can be obtained 3 About (0.52 t) gas.
About 0.85 ton of semi-coke is consumed per 1 ton of calcium carbide produced on average, and about 530Nm of calcium carbide furnace gas is produced 3 (gas density of about 1.1 kg/Nm) 3 ) Namely, about 583kg of calcium carbide furnace gas is generally produced for each 1 ton of calcium carbide. Thus, by back-pushing, 1 ton of semi-coke can be used for producing 1.18 tons of calcium carbide, and the produced calcium carbide furnace gas is about 625Nm 3 (about 688 kg). Ignoring the specific heat difference of the pyrolysis gas and the gas produced by melting the calcium carbide, and taking the specific heat of the gas as 1.672kJ/kg DEG C; the specific heat of the semi-coke is 1.045kJ/kg DEG C, and the mass ratio of the pellet semi-coke to the quicklime is calculated according to 1:1.5, and the specific heat of the quicklime is 0.59 kJ/(kg DEG C).
The waste heat recovery amount of the traditional production method is as follows:
1.672kJ/kg · c x 688kg x (2000 ℃ -500 ℃)/1000= 1725.5MJ (calcium carbide production gas waste heat recovery heat)
The waste heat recovery amount of the invention is as follows:
1.672kJ/kg · c x 688kg x (2000 ℃ -500 ℃)/1000= 1725.5MJ (calcium carbide production gas waste heat recovery heat)
1.672kJ/kg · c ×520kg× (500 ℃ -300 ℃)/1000= 167.2MJ (pyrolysis process pyrolysis gas recovery heat)
1.045 kJ/kg. Degree. C. X1000 kg x (500 ℃ C. To 25 ℃ C.)/1000= 496.4MJ (pyrolysis process coke heat recovery)
0.59 kJ/kg. Degree. C. X1500 kg. Times. (500 ℃ C. To 25 ℃ C.)/1000= 420.4MJ (quicklime requires heat to be supplied in the pyrolysis furnace, should be subtracted)
In the embodiment of preheating pellets by adopting the preheating bin of the invention, the residual heat utilization amount is calculated as follows:
1.672kJ/kg · C.times.688 kg × (500 ℃ -300 ℃) per 1000=230.1 MJ (preheating bin adopts novel structure and then the multi-heat exchanging heat of the gas generated by the calcium carbide furnace)
Therefore, the waste heat recovery amount of the invention can reach 2198.8MJ.
Therefore, the waste heat recovery amount of the invention is increased by (2198.8-1725.5)/1725.5 ×100% = 27.4% compared with the traditional method, namely, the waste heat recovery rate of the invention is increased by 27.4% compared with the traditional method.
The waste heat recovery rate refers to a ratio of sensible heat recovered from a tail end medium (e.g., pyrolysis gas, solid product) in the production process and reused in the calcium carbide production process to total sensible heat possessed by the tail end medium in the production process.
The process flow of the calcium carbide production method is shown in fig. 2, and the corresponding production system and production principle are shown in fig. 3-6, and mainly comprise the procedures of lime grinding, coal grinding, raw material (lime powder and coal dust) metering and mixing, raw material forming, pellet preheating pyrolysis, high-temperature melting, cooling, crushing and the like.
The raw materials lime and coal are milled by a mill, and the average particle size of the obtained lime powder and coal powder is 100-200nm. In the metering and mixing process, the pulverized coal and the lime powder are metered and mixed according to the mass ratio of 1.2-1.5:1, so as to obtain the mixture.
The mixture is subjected to cold press molding at room temperature under the condition of adding water-soluble binders (such as starch, dextrin, polyvinyl alcohol, carboxymethyl cellulose and the like) or solvent binders (such as shellac and butyl rubber) to obtain pellets, and the pellet strength meets the following requirements: the broken grain with the breakage rate of less than 5 millimeters after falling for 5 times at the height of 2 meters accounts for not more than 3 percent of the quantity proportion of all the pellet particles, and the physical strength of single pellets is not less than 500N. The pellets after cold press molding of the mixture are stored in a cold press molding pellet storage bin 1, and then are preheated in a preheating storage bin 2, wherein the preheating temperature can reach 200-300 ℃; and then carrying out pyrolysis reaction in a pyrolysis furnace, wherein the pyrolysis reaction temperature is 450-700 ℃, the pyrolysis reaction pressure is normal pressure, and the pyrolysis reaction time is 10-30 min. The pyrolyzed pellets obtained in the pyrolysis step are stored in a pyrolyzed pellet storage bin 5 and are continuously fed into a calcium carbide furnace 6 for high-temperature melting reaction, wherein the high-temperature melting reaction temperature is 1800-2200 ℃, the reaction pressure is normal pressure, and the reaction time is 30-120min, so that liquid calcium carbide is obtained; the obtained liquid calcium carbide flows into the calcium carbide pot 7 at regular time, and the calcium carbide flowing into the calcium carbide pot 7 is crushed into a certain required granularity specification after the cooling process, so as to obtain the finished product calcium carbide.
In the pellet preheating process, in a preheating bin 2 at the upper part of a pyrolysis furnace, the pellets are preheated by cold press molding, and the pellets are preheated by direct contact through mixed gas formed by pyrolysis gas and coal gas. The polymer such as tar contained in the mixed gas is cooled by the cold-pressed formed pellets and is trapped and adsorbed on the surfaces of the pellets to serve as a carbon source in the calcium carbide production process, and dust carried in the mixed gas (mainly from dust carried by gas discharged from a calcium carbide furnace 6 and a small amount of dust carried by pyrolysis gas) is also trapped by the pellets in the preheating bin 2 and continuously participates in the calcium carbide production process. Wherein, the pyrolysis gas is generated by the pellet pyrolysis process; the coal gas is produced in the process of producing calcium carbide by high-temperature melting of pellets; the pyrolysis gas and the gas are mixed in the mixing chamber 3. The mixture after preheating the pellets can be fed as fuel to a lime kiln for lime production (see fig. 8). In the method, the pellet preheating procedure can realize the recovery and reutilization of the waste heat of pyrolysis gas and coal gas, thereby improving the heat utilization rate of the whole calcium carbide production process and reducing the heat energy consumption of the calcium carbide production process; meanwhile, after the mixed gas of the pyrolysis gas and the coal gas is directly preheated and purified by the pellets, the tar quantity and the dust content of the mixed gas are greatly reduced, and the subsequent treatment load of the tar blockage and dust removal device of the coal gas pipeline of the lime kiln is reduced. In the preheating process, the pellets may be preheated to 200-300 ℃.
The structure schematic diagram of the preheating bin of the invention is shown in fig. 9, the preheating bin 2 of the invention is divided into an upper section, a middle section and a lower section, and a plurality of air outlet manifolds 25 are arranged on the outer wall of the upper section; a gas channel 23, a gas channel baffle 24 (a plurality of layers) and a material channel 26 are arranged in the middle section; a plurality of intake branch pipes 21 are arranged at the outer wall of the lower section.
As shown in fig. 9, the material channel 26 is arranged at the middle position of the inner cavity of the preheating bin 2; the inner cavity of the preheating bin 2 is provided with a plurality of hollow pipelines, and the inner cavity of the hollow pipelines is used as a material channel 26; the hollow conduit may be a heat resistant material, such as ceramic. The cross-sectional view of the material passage 26 and the air inlet hole 22 along the line II-II is shown in fig. 10, wherein the air inlet hole 22 is disposed on the side wall of the material passage 26 (i.e., hollow pipe), and the air can pass through the air inlet hole 22 to the side wall of the material passage 26.
As shown in fig. 9, the gas passage partition 24 is disposed between and spans the inner wall of the middle section and the side wall of the material passage 26 (i.e., the side wall of the hollow pipe), and both ends of the gas passage partition 24 are fixed to the inner wall of the middle section and the side wall of the material passage 26, respectively, thereby forming the gas passage 23 therebetween.
As shown in fig. 9, a louver 27 is further disposed on the inner side wall of the material passage 26, and one end of the louver 27 is fixed to the inner side wall of the material passage 26, and the other end thereof is extended to the inner cavity of the material passage 26 as a free end and is inclined downward. The cross-sectional view of the material passageway 26 and the shutter 27 along line II-II is shown in fig. 11, the shutter 27 being uniformly disposed on the side wall of the material passageway 26 and shielding the air intake hole 22 from the pellets flowing from top to bottom entering the air intake hole 22.
The pellets enter the preheating bin 2 from the upper section material inlet and then enter the material channel 26, and the shutter plates 27 positioned on the side walls of the material channel 26 are arranged at the front ends of the air inlet holes 22, so that the pellets can be prevented from entering the gas channel 23, and the mixed gas formed by pyrolysis gas and coal gas can freely shuttle in the gas channel 23 and the material channel 26 through the air inlet holes 22. Meanwhile, the gas channel baffles 24 are arranged between the inner wall of the middle section of the pyrolysis furnace and the side wall of the material channel 26 (namely the side wall of the hollow pipeline), so that the mixed gas forms a baffling flow in the gas channel 23, and the arrangement of the plurality of gas channel baffles 24 enables the mixed gas to be in a turbulent flow form as a whole, so that the mixed gas is promoted to more frequently pass through the air inlet holes 22, and the residence time of the mixed gas in the preheating bin 2 is prolonged.
The mixed gas enters the preheating bin 2 from the bottom of the preheating bin 2 through the air inlet branch pipe 21 in a division manner, then enters the gas channel 23 in a division manner, and the flowing direction of the mixed gas is changed under the action of the gas channel partition plate 24 arranged in the gas channel 23 to form a baffling, so that the residence time of the mixed gas in the preheating bin 2 is prolonged, the contact time and probability of the mixed gas and pellets are increased, and the waste heat exchange effect and the purifying effect of the mixed gas are enhanced.
The number of the gas channel clapboards 24 arranged in the preheating bin 2 can be 4-10, and one or more gas inlets 22 are arranged between every two gas channel clapboards 24. The air inlet hole 22 is in a circular or oval shape, and the aperture or equivalent diameter (typically 1-3 mm) of the air inlet hole 22 is much smaller than the pellet particle size to prevent the pellets from entering the gas channel 23.
In one embodiment of the invention, 2-5 layers of the shutter plates 27 are arranged along the vertical direction of the material channel 26 according to the diameter and the height of the preheating bin 2, and 4-8 shutter plates 27 are arranged on each layer.
In one embodiment of the present invention, the louver plates 27 and the material channel 26 form an included angle α of 15 to 25 ° in the vertical direction. The arrangement of the included angle can lead the pellets to form deflection in the falling process, thereby prolonging the residence time of the pellets in the preheating bin 2 and increasing the contact time and probability of the pellets and the mixed gas. In one embodiment of the present invention, the length of the louver 27 in the vertical direction is 1.0 to 1.5 times the diameter of the material passage 26. The material passageway 26 is a generally cylindrical passageway.
In order to ensure the residence time of the mixed gas in the preheating bin 2, the relative flow of the mixed gas in the material channel 26 (relative to the total flow of the mixed gas in the preheating bin 2) is controlled to be 60-70%, wherein 30-40% of the relative flow enters the gas channel 23 through the air inlet hole 22 and then returns to the material channel 26 so as to further heat the mixed gas with 60-70% of the relative flow in the material channel 26, thereby avoiding the mixed gas from forming an excessive temperature gradient in the blanking direction after heat exchange of the cold-pressed pellets, and the waste heat utilization efficiency of the mixed gas and the cold-pressed pellets can be improved to more than 85%.
In the preheating bin 2, the gas speed of the mixed gas formed by the pyrolysis gas and the coal gas is controlled to be 0.05-0.1m/s; the speed of the cold-pressed formed pellets entering the preheating bin 2 is controlled to be 0.1-0.15m/s; the contact time of the pellets and the mixed gas in the preheating bin 2 is controlled to be 1-3min, and the pellets and the mixed gas are directly subjected to full countercurrent heat exchange. Meanwhile, after dust and tar carried by the mixed gas entering the preheating bin 2 are cooled and trapped and adsorbed by cold press molding pellets through countercurrent heat exchange, when the mixed gas enters a subsequent system, the dust content of the mixed gas is reduced to about 20% of the dust content of the traditional gas (the dust content of the traditional gas is 10-25 g/m) 3 ) When entering the subsequent system, the tar content of the mixed gas is reduced to 5 percent of the tar content of the traditional gas (the tar content of the traditional gas is 5-12 g/m) 3 ）。
In the preheating bin 2, if the contact time of the pellets and the mixed gas is too long, for example, exceeds 3 minutes, the outlet temperature in the mixed gas is reduced after heat exchange, and water vapor in the mixed gas is condensed, so that the cold-pressed pellets are damped in the preheating bin and crushed, and the material flow in the preheating bin is influenced; meanwhile, the crushed powder is likely to enter the shutter, so that the material feeding state of the preheating bin and the gas-solid heat exchange are affected; if the contact time is too short, for example, less than 1min, the mixed gas temperature outlet temperature is too high, and the waste heat recovery efficiency is lowered.
In the preheating bin 2, the inlet temperature of the mixed gas formed by the pyrolysis gas and the coal gas is 1400-1700 ℃, and the outlet temperature is 300-350 ℃; the inlet temperature of the cold-pressed formed pellets is 20-25 ℃, and the temperature of the preheated pellets at the outlet is 200-300 ℃.
Fig. 10 is a horizontal sectional view of the intake hole of fig. 9.
Fig. 11 is a cross-sectional view of fig. 9 taken along line II-II.
As shown in FIG. 7, the pre-heated pellet pyrolysis process of the invention can adopt one of four modes of spiral pyrolysis, fluidized pyrolysis, rotary pyrolysis and mobile pyrolysis, the process flows of which are respectively shown in FIG. 3-FIG. 6, and the structures of the corresponding pyrolysis furnaces are respectively shown in a-d in FIG. 7. The four pyrolysis modes all adopt hot flue gas which is generated by combusting fuel and air in a combustion chamber 8 and is at 800-950 ℃, and the hot flue gas enters a pyrolysis furnace (a spiral pyrolysis furnace 41, a fluidized pyrolysis furnace 42, a rotary pyrolysis furnace 43 or a movable pyrolysis furnace 44) and directly makes countercurrent and convection contact with preheated pellets at 200-300 ℃ to generate pyrolysis reaction. The temperature in the pyrolysis furnace is controlled at 450-700 ℃, the temperature of a pyrolysis gas outlet is controlled at 420-640 ℃, the pellets are subjected to pyrolysis reaction in the pyrolysis furnace to obtain pyrolysis pellets, and the pyrolysis pellets enter a pyrolysis pellet storage bin 5 to be used as a reaction raw material of a calcium carbide furnace 6.
As shown in a of fig. 7, the schematic diagram of the screw pyrolysis furnace 41 includes a first preheating pellet feed port 411, a first pyrolysis pellet outlet 412, a first combustion hot flue gas inlet 413, a first pyrolysis gas outlet 414, which are mainly different from the conventional screw pyrolysis furnace in that:
1) The screw rod adopts a polished rod shallow internal groove screw rod, so that the problem that the porosity in a spiral pyrolysis cavity is large due to the fact that a spiral slice of a traditional screw rod conveys materials does not exist, and the spiral pyrolysis treatment capacity is affected;
2) The length of the screw terminal exceeds the center line of the pyrolysis pellet outlet by 3-5cm, the traditional screw terminal and the pyrolysis pellet outlet are not adopted, the screw terminal space is increased, and the problem that the pyrolysis material terminal pile is accumulated in the blanking is not smooth is avoided;
3) The side of the spiral pyrolysis furnace, which is close to the motor 9, is provided with a pyrolysis airtight device, so that pyrolysis gas generated in the pyrolysis process of the pyrolysis pellets in the furnace flows unidirectionally, the reaction time of the preheated pellets in the spiral pyrolysis furnace 41 is controlled by the rotating speed of the motor 9, and the pyrolysis reaction time of the preheated pellets is generally controlled to be 5-8min.
The schematic diagram of the fluidized pyrolysis furnace is shown as b in fig. 7, the fluidized pyrolysis furnace 42 comprises a second preheating pellet feed inlet 421, a second pyrolysis pellet outlet 422, a second combustion hot flue gas inlet 423 and a second pyrolysis gas outlet 424, a suspension pyrolysis mode is adopted, the operation gas speed of an airtight phase region of hot flue gas in the pyrolysis furnace is controlled to be 0.5-1.0m/s, the preheating pellets and the hot flue gas are subjected to forced heat exchange through strong turbulence caused by the hot flue gas in the furnace, the pyrolysis reaction rate is improved, and the preheating pellets complete the pyrolysis reaction in the furnace for 3-5 min.
The schematic diagram of the rotary pyrolysis furnace is shown as c in fig. 7, the rotary pyrolysis furnace 43 comprises a third preheating pellet feed inlet 431, a third pyrolysis pellet outlet 432, a third combustion hot flue gas inlet 433 and a third pyrolysis gas outlet 434, and the rotary pyrolysis furnace is horizontally installed, and the included angle alpha between the rotary pyrolysis furnace and the horizontal plane is 3-12 degrees. The preheated pellets enter the furnace from a third preheated pellet feed inlet 431 at the top of the rotary pyrolysis furnace 43, combustion hot flue gas enters the furnace from a third combustion hot flue gas inlet 433 at the bottom of the rotary pyrolysis furnace 43 to carry out direct contact countercurrent heat exchange with the preheated pellets, pyrolysis reaction occurs, the reacted pyrolysis pellets enter a pyrolysis pellet bin 5 through a third pyrolysis pellet outlet 432, and pyrolysis gas enters the mixing chamber 3 through a third pyrolysis gas outlet 434. The rotary pyrolysis furnace 43 adopts a fast rotary operation, the pyrolysis time is controlled to be 6-10min, the rotation speed of the furnace is 30-50r/min, and the flow rate of hot flue gas in the furnace is 0.3-0.8m/s. The operation under the condition can effectively increase the reaction time of the pyrolysis pellets and the hot flue gas. A plurality of groups of rotating sheets are purposely arranged in the rotary pyrolysis furnace 43, which is in operation beneficial to enhancing the turbulence degree of hot smoke in the furnace and improving the pyrolysis reaction rate of the preheated pellets.
The schematic diagram of the moving pyrolysis furnace is shown as d in fig. 7, the moving pyrolysis furnace 44 comprises a fourth preheating pellet feed inlet 441, a fourth pyrolysis pellet outlet 442, a fourth combustion hot flue gas inlet 443, and a fourth pyrolysis gas outlet 444, the preheating pellets are uniformly dispersed on the material layer of the moving pyrolysis furnace 44 by a distributor after entering the fourth preheating pellet feed inlet 441, and the pyrolysis pellets are uniformly discharged through the fourth pyrolysis pellet outlet 442 by a furnace bottom discharger. The hot flue gas mainly enters the furnace through a fourth combustion hot flue gas inlet 443 at the bottom of the furnace and is subjected to countercurrent heat exchange with the preheated pellets to carry out pyrolysis reaction, pyrolysis gas generated by the pyrolysis reaction flows upwards to a fourth pyrolysis gas outlet 444 along the axial direction of the pyrolysis furnace and is discharged into the mixing chamber 3, and a multi-layer fourth pyrolysis gas outlet 444 can be arranged in the axial direction of the movable pyrolysis furnace 44. The pyrolysis reaction time of the preheated pellets in the movable pyrolysis furnace 44 is mainly controlled by the rotation speed of the furnace bottom discharger, and the rotation speed of the discharger is usually controlled to be 0.02-0.1r/min, and the pyrolysis time of the preheated pellets in the furnace is controlled to be 0.5-2h. The moving pyrolysis furnace 44 adopts a hot flue gas and preheating pellet internal heating mode and a multi-layer exhaust mode, and the pyrolysis temperature can be strictly carried out according to a temperature rising curve and is not easily influenced by exhaust.
In the high-temperature melting process, pyrolytic pellets at 500-600 ℃ in a pyrolytic pellet bin 5 are added into a calcium carbide furnace 6 through an upper inlet or a pipeline. In an open or closed calcium carbide furnace 6, heating to 1800-2200 ℃ to generate high-temperature melting reaction to produce calcium carbide, enabling qualified molten calcium carbide to flow into a calcium carbide pot 7 through a calcium carbide outlet of the calcium carbide furnace 6 to be collected, returning gas which is generated in the calcium carbide furnace 6 and is at 1800-2000 ℃ to a mixing chamber 3 to be mixed with pyrolysis gas, and then entering a preheating bin 2 to perform pellet preheating.
In the cooling and crushing process, molten calcium carbide in a calcium carbide pot 7 is pulled to a corridor or a packaging room by a winch for cooling, a solidified calcium carbide block is hung out by a bridge crane and a single holding clamp, is placed on the cast iron ground for cooling, and after cooling to a proper level, the calcium carbide is crushed to a qualified granularity, and then packaged in a grading manner and sent to a finished product warehouse.
In summary, the novel calcium carbide production method and production system directly adopt the mixed pellets of the pulverized coal and the lime powder as raw materials, integrate the process of producing coke by pyrolyzing the pulverized coal and the process of mixing the coke and the lime into one step, and carry out high-temperature melting in a calcium carbide furnace to produce calcium carbide, thereby realizing the continuity of the calcium carbide production process, omitting the coke making step of the traditional calcium carbide production process and reducing the production cost of the calcium carbide; meanwhile, raw materials are preheated after the pyrolysis gas generated in the coal pyrolysis process and the coal gas generated in the high-temperature melting process of the calcium carbide are mixed, so that the defect that the waste heat of the coal gas is not fully utilized in the traditional calcium carbide production process is overcome, and the energy consumption and the calcium carbide cost in the calcium carbide production process are reduced; meanwhile, the pyrolysis pellets produced by the preheating pellet pyrolysis furnace can directly enter the pyrolysis pellet bin to be used as a raw material of the calcium carbide furnace, so that the hot coke powder quenching procedure after coke making in the traditional calcium carbide production process is omitted, and the heat loss in the quenching process is avoided. Therefore, the overall waste heat recovery rate of the novel calcium carbide production method and production system can reach 75-80%, and the waste heat recovery rate (55-60%) is improved by 25-45% compared with the traditional calcium carbide production process (the specific difference point is as before).
Example 1:
lime and coal are respectively processed by respective grinding machines to produce lime powder and coal powder with average particle size of 150 nm. The lime powder and the coal powder are metered and uniformly mixed according to the mass ratio of 1.0:1.2, 100 tons of mixture is produced, the mixture is subjected to cold press molding at room temperature under the condition of adding polyvinyl alcohol, and the strength of the obtained single pellets is 500N.
The pellets after cold press molding of the mixture are subjected to heat exchange with mixed gas formed by pyrolysis gas and coal gas in a preheating bin 2, and the speed of the pellets entering the preheating bin 2 is 0.1-0.15m/s; the temperature of the mixed gas at the inlet of the preheating bin 2 is 1400-1700 ℃, the temperature of the mixed gas at the outlet of the preheating bin 2 is 300-350 ℃ after heat exchange, and then the mixed gas is circulated to a lime kiln to be used as fuel, and the temperature of pellets after preheating is 200-300 ℃. The number of the gas passage clapboards 24 arranged in the preheating bin 2 is 4, the layers of the shutter plates 27 arranged along the axial direction of the preheating bin 2 are 4, 8 shutter plates 27 are arranged on each layer, and the installation angle alpha of the shutter plates 27 is 20 degrees. The contact time of the pellets and the mixed gas is about 3min.
The hot flue gas at the temperature of about 850 ℃ generated by combustion in the combustion chamber 8 enters the spiral pyrolysis furnace 41 to directly contact with the preheated pellets for pyrolysis reaction, the pyrolysis reaction time is controlled to be 5.5min, the temperature in the spiral pyrolysis furnace 41 is controlled to be about 580 ℃, the pyrolysis gas outlet temperature of the spiral pyrolysis furnace 41 is controlled to be 540 ℃, and the pyrolysis pellets at the temperature of about 520 ℃ enter the pyrolysis pellet bin 5 to be used as raw materials for the calcium carbide furnace 6.
The calcium carbide furnace 6 body is used for producing 3.5 tons/hour of calcium carbide, the high-temperature melting temperature is controlled to be about 2000 ℃, and the tar content of the obtained gas is 9.8g/m after detection 3 (2000 ℃ C.) the dust content of the gas was 16g/m 3 （2000℃）。
The gas at about 2000 ℃ enters the mixing chamber 3 to be mixed with the pyrolysis gas, the temperature of the obtained mixed gas is about 1500 ℃ (the temperature is monitored by a temperature sensor arranged at the air inlet branch pipe 21 and not shown), the gas speed of the mixed gas entering the preheating bin 2 is 0.05-0.1m/s, and the flow rate is controlled as follows: the relative flow rate of the mixture gas in the material passage 26 is 70%, and the relative flow rate of the mixture gas in the gas passage 23 is 30%. The flow rate of the mixed gas is controlled by a three-way flow valve (ceramic material, not shown) arranged at the lower section of the preheating bin 2, and three passages of the three-way flow valve are respectively communicated with the air inlet branch pipe 21, the gas passage 23 and the material passage 26.
The temperature of the mixture at the outlet of the preheating silo 2 was about 320 c (monitored by a temperature sensor (not shown) provided at the outlet manifold 25), and the tar content of the mixture was detected to be 3.0g/m 3 The dust content of the mixed gas is 2.5g/m 3 The time when the pressure drop of the gas bag dust collector reaches 1200Pa is prolonged from 1.0h to 3.5h of a preheating purification system of a preheating bin 2, and the waste heat recovery rate of the whole calcium carbide production process can reach about 77.6 percent.
The calculation mode of the waste heat recovery rate is as follows: waste heat recovery = (heat before heat exchange of mixture-heat after heat exchange of mixture)/heat before heat exchange of mixture x 100%.
Example 2:
lime and coal respectively pass through respective mills to obtain lime powder and coal powder with average granularity of 100 nm. The lime powder and the coal powder are metered and uniformly mixed according to the mass ratio of 1.0:1.5, 150 tons of mixture is obtained, the mixture is subjected to cold press molding at room temperature under the condition of adding shellac, and the strength of the obtained single pellet is 550N.
In the same manner as in example 1, the pellets after cold press molding of the mixture are subjected to heat exchange with a mixed gas formed of pyrolysis gas and coal gas in the preheating silo 2.
In this embodiment 2, 6 gas passage separators 24 are provided in the preheating silo 2, layers 3 of shutter plates 27 are arranged along the axial direction of the preheating silo 2, 6 shutter plates 27 are arranged in each layer, and the installation angle α of the shutter plates 27 is 18 °. The contact time of the pellets and the mixed gas is about 1 min.
In the manner of example 1, the preheated pellets were subjected to a pyrolysis reaction in the screw pyrolysis furnace 41, and the obtained pyrolysis pellets were fed into the pyrolysis pellet bin 5 as raw materials for the calcium carbide furnace 6.
The high-temperature melting temperature of the calcium carbide furnace 6 is controlled to be about 2050 ℃, and the tar content of the obtained gas is 10.2g/m after detection 3 (2050 ℃) gas dust content 18.5g/m 3 （2050℃）。
The relative flow and temperature of the mixture in the preheating silo 2 were controlled in the manner of example 1. In this example 2, the dust content of the mixture gas at the outlet of the preheating silo 2 was measured to be 2.46g/m 3 Tar content of 3.2g/m 3 . The time when the pressure drop of the gas bag dust collector reaches 1200Pa is prolonged from 1.5 hours to 4.2 hours of a preheating purification system of a preheating bin 2, and the waste heat recovery rate of the whole calcium carbide production process can reach about 78.0 percent.
The calculation mode of the waste heat recovery rate is as follows: waste heat recovery = (heat before heat exchange of mixture-heat after heat exchange of mixture)/heat before heat exchange of mixture x 100%.
Claims (9)
1. The calcium carbide production method is characterized by comprising the following steps of:
(1) Mixing the crushed raw material lime with coal in the presence of a binder, and then cold-pressing and molding to obtain pellets; the strength of the pellets meets the breakage rate after the pellets fall for 5 times at the height of 2 meters, namely, the number proportion of the broken pellets smaller than 5 millimeters to all the pellets is not more than 3 percent;
(2) Preheating and pyrolyzing the pellets successively;
(3) Carrying out high-temperature melting reaction on the pyrolyzed pellets obtained by the pyrolysis reaction to generate liquid calcium carbide, cooling and crushing the discharged liquid calcium carbide to form finished product calcium carbide, wherein the temperature of the high-temperature melting reaction is 1800-2200 ℃;
wherein the preheating is achieved by contacting the pellets with a mixture of pyrolysis gas produced by the pyrolysis reaction and gas produced by the high temperature melting reaction,
the preheating is performed in a preheating bin; the pyrolysis reaction is performed in a pyrolysis furnace; the high-temperature melting reaction is carried out in a calcium carbide furnace;
the preheating bin, the pyrolysis furnace and the calcium carbide furnace are communicated through a mixing chamber, so that pyrolysis gas generated in the pyrolysis furnace and coal gas generated in the calcium carbide furnace are mixed in the mixing chamber and then are introduced into the preheating bin,
an air inlet branch pipe, a material channel and an air outlet main pipe are arranged in the preheating bin; the air inlet branch pipe is positioned at the lower section of the preheating bin, the air outlet main pipe is positioned at the upper section of the preheating bin, and the material channel is arranged in the inner cavity of the preheating bin;
a shutter plate is arranged on the side wall in the material channel, one end of the shutter plate is fixed on the side wall of the material channel, and the other end of the shutter plate is used as a free end to extend to the inner cavity of the material channel and incline downwards;
an air inlet is arranged on the side wall of the material channel, and air can pass through the side wall of the material channel through the air inlet.
2. The method for producing calcium carbide according to claim 1, wherein: the contact time is 1-3min.
3. The method for producing calcium carbide according to claim 1, wherein: in the step (2), the preheating is performed to 200-300 ℃.
4. The method for producing calcium carbide according to claim 1, wherein: in the step (1), the step of (a),
the binder is selected from one or more of water-soluble binders or solvent binders; or the binder is selected from a mixture of a water-soluble binder and a solvent-type binder;
the water-soluble binder is selected from one or more of starch, dextrin, polyvinyl alcohol or carboxymethyl cellulose;
the solvent type binder is selected from shellac or butyl rubber; or the solvent-based adhesive is a mixture of shellac and butyl rubber.
5. The method for producing calcium carbide according to claim 1, wherein: in the step (1), the grinding and pulverizing is to grind the average particle size of the raw material lime and coal to 100-200nm.
6. The method for producing calcium carbide according to claim 1, wherein: in the step (1), the mixing mass ratio of the raw lime to the coal is 1:1.2-1.5.
7. A calcium carbide production system for carrying out the method for producing calcium carbide according to any one of claims 1 to 6, characterized in that: the production system comprises a crushing device, a cold press molding bin, a preheating bin, a pyrolysis furnace, a calcium carbide furnace and a mixing chamber which are connected in sequence;
the crushing device is used for crushing raw lime and coal;
the cold press molding bin is used for storing the pellets after cold press molding;
the preheating bin is used for preheating the pellets;
the pyrolysis furnace is used for carrying out pyrolysis reaction of the pellets;
the calcium carbide furnace is used for carrying out high-temperature melting reaction of the pyrolyzed pellets;
the preheating bin, the pyrolysis furnace and the calcium carbide furnace are communicated through the mixing chamber, so that pyrolysis gas generated in the pyrolysis furnace and coal gas generated in the calcium carbide furnace are mixed in the mixing chamber and then are introduced into the preheating bin;
an air inlet branch pipe, a material channel and an air outlet main pipe are arranged in the preheating bin; the air inlet branch pipe is positioned at the lower section of the preheating bin, the air outlet main pipe is positioned at the upper section of the preheating bin, and the material channel is arranged in the inner cavity of the preheating bin;
the material channel is characterized in that a louver board is arranged on the side wall in the material channel, one end of the louver board is fixed on the side wall of the material channel, the other end of the louver board serves as a free end to extend to the inner cavity of the material channel and incline downwards, an air inlet hole is arranged on the side wall of the material channel, and air can pass through the side wall of the material channel through the air inlet hole.
8. The calcium carbide production system according to claim 7, wherein: the material channel is provided with a plurality of layers along the vertical direction, each layer is provided with a plurality of shutter plates, and the included angle alpha between the shutter plates and the material channel in the vertical direction is 15-25 degrees.
9. The calcium carbide production system according to claim 8, wherein: the production system also comprises one or more components in a combustion chamber, a pyrolysis pellet bin or a calcium carbide pot;
the combustion chamber is connected with the pyrolysis furnace, so that flue gas generated in the combustion chamber is introduced into the pyrolysis furnace and used for heating to carry out pyrolysis reaction;
the pyrolysis pellet bin is connected with the pyrolysis furnace and the calcium carbide furnace and is used for storing pyrolysis pellets obtained after pyrolysis reaction;
the calcium carbide pot is connected with the calcium carbide furnace, and liquid calcium carbide is led out and enters the calcium carbide pot.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB723455A (en) * | 1951-07-30 | 1955-02-09 | Air Reduction | Improvements in preparation of a charge for a calcium carbide furnace |
| CN107364866A (en) * | 2017-06-28 | 2017-11-21 | 大连华锐重工集团股份有限公司 | A kind of low-order coal prepares the method and compound binding agent of calcium carbide furnace charge |
| CN107473225A (en) * | 2016-06-08 | 2017-12-15 | 神雾环保技术股份有限公司 | Prepare the system and method for calcium carbide |
| CN209922906U (en) * | 2019-03-13 | 2020-01-10 | 北京双零矿山装备技术有限公司 | System for production carbide |
| CN210795784U (en) * | 2019-08-07 | 2020-06-19 | 铂尊投资有限公司 | System for production carbide |
-
2023
- 2023-06-19 CN CN202310727337.1A patent/CN116443879B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB723455A (en) * | 1951-07-30 | 1955-02-09 | Air Reduction | Improvements in preparation of a charge for a calcium carbide furnace |
| CN107473225A (en) * | 2016-06-08 | 2017-12-15 | 神雾环保技术股份有限公司 | Prepare the system and method for calcium carbide |
| CN107364866A (en) * | 2017-06-28 | 2017-11-21 | 大连华锐重工集团股份有限公司 | A kind of low-order coal prepares the method and compound binding agent of calcium carbide furnace charge |
| CN209922906U (en) * | 2019-03-13 | 2020-01-10 | 北京双零矿山装备技术有限公司 | System for production carbide |
| CN210795784U (en) * | 2019-08-07 | 2020-06-19 | 铂尊投资有限公司 | System for production carbide |
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| CN116443879A (en) | 2023-07-18 |
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