CN106276903B - A kind of system and method for preparing hydrogen-rich gas and calcium carbide - Google Patents

Abstract

The invention relates to a system and method for preparing hydrogen-rich gas and calcium carbide. The system includes high-temperature pyrolysis unit, catalytic reforming unit, conversion, decarbonization unit and calcium carbide smelting unit. The whole unit includes the inlet of raw coal gas and the outlet of synthesis gas; the transformation and decarbonization unit includes the inlet of synthesis gas and the outlet of hydrogen-rich gas; the calcium carbide smelting unit includes the inlet of solid material, the inlet of oxygen-containing gas and the outlet of calcium carbide, which is used for the preparation of calcium carbide by oxygen thermal method; The solid material inlet is connected with the high-temperature mixed powder outlet of the high-temperature pyrolysis unit. The system and method for preparing hydrogen-rich gas and calcium carbide of the present invention not only utilize the heat of pyrolysis gas, but also convert the complex composition of pyrolysis gas into hydrogen-rich gas.

Description

A system and method for preparing hydrogen-rich gas and calcium carbide

technical field

The invention mainly relates to the production field of calcium carbide, in particular to a system and method for preparing hydrogen-rich gas and calcium carbide.

Background technique

The process of preparing calcium carbide by oxythermal method after pyrolysis of powdery medium-low rank coal and powdery quicklime as raw materials to obtain high-temperature active semi-coke has been extensively studied. This process has made a major breakthrough in terms of raw material cost and thermal efficiency. However, in this process, the heat of active semi-coke after pyrolysis is fully utilized, while a large amount of heat carried by raw gas is cooled and wasted in the subsequent separation process. In addition, in the continuously developed calcium carbide acetylene chemical process, calcium carbide reacts with water to produce a large amount of calcium carbide slag (the main component is calcium hydroxide). If it is not effectively utilized, it will not only cause waste of resources, but also cause adverse effects on the surrounding environment. surroundings.

At the same time, the pyrolysis gas produced by coal pyrolysis contains a large amount of methane and carbon monoxide, and steam reforming of methane and carbon monoxide shift reaction are relatively mature methods in industry for producing hydrogen-rich gas from gas containing methane and carbon monoxide. The main reaction Including the reaction of methane and water vapor to produce carbon monoxide and hydrogen, and the reaction of carbon monoxide and water vapor to produce carbon dioxide and hydrogen. Considering that the temperature of the pyrolysis gas obtained by high-temperature pyrolysis of spherical balls is similar to the steam reforming reaction of methane, if the methane and carbon monoxide in the pyrolysis gas are converted into hydrogen through steam reforming reaction and shift reaction, the pyrolysis The gas becomes an _H2 -rich gas.

In addition, because water vapor is required in both methane steam reforming and carbon monoxide shifting processes, part of calcium carbide slag can be added to quicklime as raw material for calcium carbide production. In this way, the calcium oxide in the carbide slag can not only be turned into raw materials, reducing the cost of raw materials, but also the water in the carbide slag can also be turned into the raw material for the high-temperature catalytic reaction of pyrolysis gas, which can save the steps of drying and calcination of the carbide slag slurry. Further save energy consumption.

Therefore, in view of the above problems, it is necessary to invent a system and method for preparing hydrogen-rich gas and calcium carbide, which can make full use of the components in the raw materials and the energy of the pyrolysis gas, and convert them into gas products with higher added value.

Contents of the invention

In view of the above problems, the present invention aims to provide a system and method for preparing hydrogen-rich gas and calcium carbide. The purpose of the system and method is to solve the problems of heat loss carried by pyrolysis gas and low utilization efficiency of pyrolysis gas when producing calcium carbide. Further, the present invention can also reduce the cost of calcium carbide raw materials and make full use of calcium carbide slag.

The system for preparing hydrogen-rich gas and calcium carbide provided by the present invention includes: a high-temperature pyrolysis unit, a catalytic reforming unit, a conversion and decarburization unit, and a calcium carbide smelting unit, wherein the high-temperature pyrolysis unit includes a coal powder inlet, a calcium-based raw material The inlet, raw coal gas outlet and high-temperature mixed powder outlet are used for pyrolysis of calcium carbide raw materials; the catalytic reforming unit includes a raw coal gas inlet and a synthesis gas outlet, which are used for catalytic reforming of methane and water vapor; the raw coal gas The inlet is connected to the raw coal gas outlet of the high-temperature pyrolysis unit; the conversion and decarbonization unit includes a synthesis gas inlet and a hydrogen-rich gas outlet, which are used for the catalytic conversion reaction of carbon monoxide and the decarbonization treatment of the generated gas; the synthesis gas The inlet is connected to the synthesis gas outlet of the catalytic reforming unit; the calcium carbide smelting unit includes a solid material inlet, an oxygen-containing gas inlet and a calcium carbide outlet, which are used for preparing calcium carbide by the oxygen thermal method; the solid material inlet is connected to the high-temperature thermal The high-temperature mixed powder outlet of the solution unit is connected.

In the above-mentioned system, the catalytic reforming unit is a reforming reactor, and a filter layer, a catalyst layer for catalytic cracking of tar, and a catalyst layer for methane reforming are arranged in sequence inside it from bottom to top.

In the above system, the shift and decarburization unit includes a shift furnace, and a shift catalyst layer is arranged inside the shift furnace.

In the above-mentioned system, the system further includes an insulated conveying device, and the insulated conveying device is connected with the solid material inlet of the calcium carbide smelting unit and the high-temperature mixed powder outlet of the high-temperature pyrolysis unit.

Further, in the above system, the high-temperature pyrolysis unit is a regenerative down-bed reactor, and multi-layer regenerative radiant tubes are arranged inside it.

Further, the system can also include a raw material processing unit, which includes a sequentially connected coal crushing device, an intermediate coal storage bin, and a coal powder screw conveying device, and a sequentially connected calcium-based raw material crushing device, calcium Base raw material intermediate storage warehouse, calcium base raw material powder screw conveying device.

The present invention also provides a method for preparing hydrogen-rich gas and calcium carbide by using the above system, which includes the following steps: sending coal powder with a particle size of <1mm and calcium-based raw materials with a particle size of <3mm into the high-temperature pyrolysis unit for pyrolysis , to obtain raw coal gas and high-temperature mixed powder; send the raw coal gas to the catalytic reforming unit, obtain synthesis gas through filtration, catalytic cracking of tar and catalytic reforming of methane; send the synthesis gas to the conversion, The decarburization unit performs a conversion reaction, so that the carbon monoxide in the synthesis gas is converted into hydrogen and carbon dioxide, and then a hydrogen-rich gas is obtained after decarburization; the high-temperature mixed powder is sent to the calcium carbide smelting unit, and the oxythermal method Calcium carbide is produced by smelting.

In the above method, the calcium-based raw material includes calcium carbide slag and quicklime, and the added amount of the calcium carbide slag is 20wt%-40wt% of the quicklime; the mass ratio of the calcium-based raw material to the coal powder is 1.0-40wt%. 1.5:1.

In the above method, the temperature of the catalytic reforming is 700-900°C, and the pressure is 2-4MPa; the temperature of the shift reaction is 200-320°C, and the catalyst of the shift reaction is a Co-Mo series sulfur resistant wide temperature catalyst.

The above method, the method may also include the step of: sending coal and calcium-based raw materials into the raw material processing unit, making the coal crushed to <1mm to become coal powder, making the calcium-based raw materials crushed to <3mm; the coal For medium and low price coal.

The technical scheme of the present invention enables the high-temperature water vapor and the pyrolysis gas to be catalytically reacted in the catalytic reforming reactor and the shift furnace to finally obtain hydrogen-rich gas. On the one hand, the heat of the pyrolysis gas can be fully utilized, and on the other hand Pyrolysis gas with complex composition can be converted into hydrogen-rich gas.

In the present invention, part of the carbide slag can be used to replace the calcium oxide, so that the calcium carbide slag can be turned from waste to treasure, and carbonization and calcination steps are not required, thereby reducing the cost of raw materials. At the same time, the water vapor produced by the decomposition of calcium hydroxide is used to react with methane and carbon monoxide in the pyrolysis gas. Since the water vapor produced by the decomposition of calcium hydroxide is more, the carbon deposition of the catalyst can be reduced and the life of the catalyst can be extended.

Furthermore, the high-temperature mixed powder produced by pyrolysis in the present invention can be transported to the calcium carbide furnace with heat preservation, which improves the heat utilization efficiency of the system.

The present invention produces calcium carbide by oxythermal method, and the raw material is always powder from pyrolysis to calcium carbide smelting unit, which saves the molding unit, simplifies the system and operation process, and increases the reaction contact area between raw materials, thus improving heat transfer efficiency.

Description of drawings

Fig. 1 is a schematic structural diagram of a system for preparing hydrogen-rich gas and calcium carbide according to an embodiment of the present invention;

Fig. 2 is a flow chart of a system for preparing hydrogen-rich gas and calcium carbide according to an embodiment of the present invention.

Detailed ways

As shown in FIG. 1 , the calcium carbide production system described in the present invention consists of a raw material processing unit 1 , a high-temperature pyrolysis unit 2 , a catalytic reforming unit 3 , a conversion and decarburization unit 4 and a calcium carbide smelting unit 5 .

In order to reduce the cost of raw materials and give full play to the function of this system, the coal in the present invention is medium-low rank pulverized coal.

The raw material processing unit 1 is used for crushing raw coal and lime or calcium carbide slag, which includes a coal crushing device 11, a calcium-based raw material crushing device 12, an intermediate coal storage bin 13, a calcium-based raw material intermediate storage bin 14, and a coal powder screw conveying device 15 and calcium-based raw material powder screw conveyor 16. The crushing device is sequentially connected with the intermediate storage bin screw conveying device. Of course, in the present invention, the raw material processing unit 1 is not required to be installed, and whether it needs to be installed can be determined according to the size of the incoming material.

The device of the high-temperature pyrolysis unit 2 is a fast pyrolysis furnace, which is provided with a pulverized coal inlet 21, a calcium-based raw material inlet 22, a raw coal gas outlet 23, and a high-temperature mixed powder outlet 24; the pulverized coal inlet 21 can be screwed with the pulverized coal The device 15 is connected; the calcium-based raw material inlet 22 can be connected with the calcium-based raw material screw conveying device 16; wherein the fast pyrolysis furnace refers to a regenerative down-bed reactor, and a multi-layer regenerative radiant tube is arranged inside . The high-temperature pyrolysis unit 2 is used to pyrolyze the raw materials and output high-temperature mixed powder and raw coal gas.

The device of the catalytic reforming unit 3 is a reforming reactor, which is used for catalytic reforming reaction of methane and water vapor in the pyrolysis gas, and is provided with a raw coal gas inlet 31 and a synthesis gas outlet 36 . The raw coal gas inlet 31 is connected with the raw coal gas outlet 23 of the high temperature pyrolysis unit 2 . The reforming reactor is provided with a gas distributor 32 , and a filter layer 33 , a tar catalytic cracking catalyst layer 34 , and a methane reforming catalyst layer 35 arranged in sequence from bottom to top. The gas distributor 32 is used to make the gas pass through the catalyst layer more uniformly. The filter layer can be a ceramic filter plate, the purpose is to remove the dust in the raw gas and play the role of heat storage. The purpose of the tar catalytic cracking catalyst is to fully catalyze the tar in the raw coal gas to obtain pyrolysis gas. The purpose of the reforming catalyst layer is to catalyze the reaction of methane in the pyrolysis gas with water vapor to convert methane into hydrogen and carbon monoxide.

The device of the shift and decarburization unit 4 includes a shift furnace and a carbon dioxide absorption device, which are used for the shift reaction of carbon monoxide and the decarburization treatment of the generated gas to produce hydrogen-rich gas, and are provided with a synthesis gas inlet 41 and a hydrogen-rich gas outlet 44 . The synthesis gas inlet 41 is connected to the synthesis gas outlet 36 of the catalytic reforming unit 3 . A gas distributor 42 and a shift catalyst layer 43 are arranged inside the shift furnace. The gas distributor 42 is provided to enable the gas to pass through the catalyst layer more uniformly. The purpose of the shift catalyst layer 43 is to catalyze the shift reaction of carbon monoxide to generate rich carbon dioxide and hydrogen. After the carbon dioxide is removed by the carbon dioxide absorption device, hydrogen-rich gas can be obtained.

The device of the calcium carbide smelting unit 5 is an entrained flow bed, which is used to generate calcium carbide by the oxythermal method, and is provided with a solid material inlet 51 , an oxygen-containing gas inlet 52 , a calcium carbide furnace gas outlet 53 and a calcium carbide outlet 54 . The molten calcium carbide is exported from the calcium carbide liquid outlet 54 and then cooled to form calcium carbide products. The solid material inlet 51 can be connected with the high-temperature mixed powder outlet 24 of the high-temperature pyrolysis unit through an insulated conveying device. The heat preservation conveying device may be one of heat preservation barrels or heat preservation chain plates. Setting the heat preservation conveying device can further improve the heat utilization efficiency of the system. The heat preservation conveying device does not have to be provided either.

The system flow chart shown in Figure 2 discloses the method for preparing hydrogen-rich gas and calcium carbide by the present invention using the above system, including the following steps:

Raw material pretreatment, that is, through the crushing device, the medium and low-rank coal is crushed to <1mm, and the calcium-based raw material is crushed to <3mm; of course, this step is not mandatory, depending on the size of the incoming material.

Mixed pyrolysis, powdered coal and calcium-based raw materials are added to the powder pyrolysis device to obtain raw coal gas and high-temperature mixed powder. Wherein, the addition amount of calcium carbide slag is 20wt%-40wt% of quicklime; the mass ratio of calcium-based raw material to coal powder is 1.0-1.5:1. The pyrolysis temperature is 800-1100°C, and the pyrolysis time is 15-45min.

Catalytic reforming, pyrolyzed raw coal gas enters the catalytic reforming unit, and is filtered, tar catalytic cracking and methane catalytic reforming to obtain synthesis gas. Wherein, the temperature of the catalytic reforming unit is 700-900° C.; the pressure is 2-4 MPa.

Catalytic shift, decarburization, catalytically reformed synthesis gas, further undergoes shift reaction, converts carbon monoxide into hydrogen and carbon dioxide, and then decarburizes to obtain hydrogen-rich gas. The temperature of the shift reaction is 200-320° C., and the catalyst used is a Co-Mo series sulfur-resistant wide-temperature catalyst.

The high-temperature mixed powder is sent to the calcium carbide smelting device through the heat preservation conveying device, and is smelted by oxygen thermal method at 1750-2200 ℃ to obtain liquid calcium carbide and calcium carbide furnace gas.

According to the above technical proposal of the present invention, the hydrogen-rich gas is finally obtained after catalytic reaction between the high-temperature water vapor and the pyrolysis gas in the catalytic reforming reactor and the shift furnace. On the one hand, the heat of the pyrolysis gas can be fully utilized, and on the other hand On the one hand, it can convert pyrolysis gas with complex composition into hydrogen-rich gas. Furthermore, in the present invention, part of the carbide slag can be used to replace the calcium oxide, so that the carbide slag can be turned from waste to treasure, and the steps of carbonization and calcination are not required, which reduces the cost of raw materials. At the same time, the water vapor produced by the decomposition of calcium hydroxide is used to react with methane and carbon monoxide in the pyrolysis gas. Since the water vapor produced by the decomposition of calcium hydroxide is more, the carbon deposition of the catalyst can be reduced and the life of the catalyst can be extended.

As an extension, the present invention can also react the obtained calcium carbide with water to produce acetylene and carbide slag, which can be used as raw materials after purification, and the system can form a closed loop.

Furthermore, the high-temperature mixed powder produced by pyrolysis in the present invention can be transported to the calcium carbide furnace with heat preservation, which further improves the heat utilization efficiency.

The present invention produces calcium carbide by oxythermal method, and the raw material is always powder from pyrolysis to calcium carbide smelting unit, which saves the molding unit, simplifies the system and operation process, and increases the reaction contact area between raw materials, thus improving heat transfer efficiency.

"wt%" appearing herein refers to weight percentage.

Example 1

Using long-flame coal and quicklime added with 30wt% calcium carbide slag as raw materials, the raw coal particle size is first crushed to <1mm, and the calcium-based raw material particle size is crushed to <3mm by a crushing and grinding device; The mixture with a mass ratio of 1.0 is sent to a high-temperature pyrolysis device through a screw conveying device, and is pyrolyzed at 850°C for 25 minutes to obtain raw coal gas and high-temperature mixture powder. The raw coal gas is directly transported to the catalytic reforming conversion reactor at high temperature. The temperature in the reactor is kept at 800°C and the pressure is 2MPa. After catalytic conversion at 320°C in the furnace, the pyrolysis gas is finally composed of carbon dioxide and hydrogen, and then decarburized to obtain a high-concentration H2-rich gas; the high-temperature mixed powder is sent to the calcium carbide smelting unit through a closed heat preservation conveying equipment Inside, calcium carbide is produced by oxythermal method at 1900°C; after calcium carbide reacts with water, a large amount of calcium carbide slag can be obtained, which can be recycled as raw material for calcium carbide production after purification.

Example 2

Using long-flame coal and quicklime with 20wt% calcium carbide slag as raw materials, first crush the raw coal particle size to <1mm, and the calcium-based raw material particle size to <3mm through a crushing and grinding device; The mass ratio of 1.5 is mixed, and sent to the high-temperature pyrolysis device through the screw conveying device for pyrolysis at 900 ° C for 30 minutes to obtain raw coal gas and high-temperature mixed powder. The raw coal gas is directly transported to the catalytic reforming conversion reactor at high temperature. The temperature in the reactor is kept at 700°C and the pressure is 4MPa. After catalytic conversion at 260°C in the furnace, the pyrolysis gas is finally composed of carbon dioxide and hydrogen, and then decarburized to obtain a high-concentration H2 _- rich gas; the high-temperature mixed powder is sent to the calcium carbide smelting through the airtight heat preservation conveying equipment In the unit, calcium carbide is produced by oxythermal method at 2000°C; after the subsequent reaction of calcium carbide with water, a large amount of calcium carbide slag can be obtained, which can be recycled as raw material for calcium carbide production after purification.

Example 3

Using long-flame coal and quicklime with 40wt% calcium carbide slag as raw materials, first crush the raw coal particle size to <1mm, and the calcium-based raw material particle size to <3mm through a crushing and grinding device; Mixed at a mass ratio of 1.25:0.12, sent to a high-temperature pyrolysis device via a screw conveying device, and pyrolyzed at 1000°C for 30 minutes to obtain raw coal gas and high-temperature mixed powder. The raw coal gas is directly transported to the catalytic reforming conversion reactor at high temperature. The temperature in the reactor is kept at 900°C and the pressure is 3MPa. After catalytic conversion at 200°C in the furnace, the pyrolysis gas is finally composed of carbon dioxide and hydrogen, and then decarburized to obtain a high-concentration H2 _- rich gas; the high-temperature mixed powder is sent to the calcium carbide furnace through a closed heat preservation conveying equipment Inside, calcium carbide is produced by oxygen thermal method at 2000°C; after calcium carbide reacts with water, a large amount of calcium carbide slag can be obtained, which can be recycled as raw material for calcium carbide production after purification.

It can be seen from the above examples that the technical solution of the present invention solves the problem of waste of pyrolysis gas in the production of calcium carbide. Further, the present invention can also reduce the cost of calcium carbide raw materials and make full use of calcium carbide slag.

Finally, it should be noted that obviously, the above-mentioned embodiments are only examples for clearly illustrating the present invention, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. However, the obvious changes or variations derived therefrom are still within the protection scope of the present invention.

Claims (10)

1. a kind of system for preparing hydrogen-rich gas and calcium carbide, the system includes high temperature pyrolysis unit, catalytic reforming units, change Change, decarburization unit and calcium carbide smelting unit, wherein,

The high temperature pyrolysis unit includes coal powder entrance, calcium based raw material entrance, raw coke oven gas outlet and the outlet of high temperature mixed powder, uses In the pyrolysis of carbide raw material；The catalytic reforming units include raw coke oven gas entrance and syngas outlet, for methane and vapor Catalytic reforming；The raw coke oven gas entrance is connected with the raw coke oven gas outlet of the high temperature pyrolysis unit；

The conversion, decarburization unit include synthesis gas entrance and hydrogen-rich gas exports, and the catalytic shift for carbon monoxide is reacted Carbonization treatment with generating gas；The synthesis gas entrance is connected with the syngas outlet of the catalytic reforming units；

The calcium carbide, which smelts unit, includes solid material inlet, oxygen-containing gas entrance and calcium carbide outlet, and electricity is prepared for the hot method of oxygen Stone；The solid material inlet is connected with the high temperature mixed powder outlet of the high temperature pyrolysis unit.

2. system according to claim 1, it is characterised in that the catalytic reforming units are reforming reactor, inside it Filter layer, the catalyst layer of catalytic cracking of tar, the catalyst layer of methane reforming are sequentially provided with from the bottom up.

3. system according to claim 1, it is characterised in that the conversion, decarburization unit include change furnace, the conversion Furnace interior is provided with transformation catalyst layer.

4. system according to claim 1, it is characterised in that the system also includes heat-insulation conveying device, the insulation Conveying device smelts the solid material inlet of unit with the calcium carbide and the high temperature mixed powder of the high temperature pyrolysis unit exports It is connected.

5. system according to claim 1, it is characterised in that the high temperature pyrolysis unit reacts for heat accumulating type down-flow fluidized bed using ECT Device, it is internally provided with multilayer heat accumulation type radiant tube.

6. system according to claim 1, it is characterised in that the system also includes material processing unit, the raw material Processing unit includes sequentially connected coal breaker, coal centre warehouse and pulverized coal screw conveying device, and be sequentially connected Warehouse, calcium base feed powder helix transporting device among calcium based raw material breaker, calcium based raw material.

7. a kind of method for preparing hydrogen-rich gas and calcium carbide using any one of claim 1 to 6 system, including following step Suddenly：

By particle diameter<1mm coal dust, particle diameter<3mm calcium based raw material is sent into the high temperature pyrolysis unit and is pyrolyzed, and obtains waste coal Gas and high temperature mixed powder；

The raw coke oven gas is sent into the catalytic reforming units, filtered, catalytic cracking of tar and methyl hydride catalyzed reformation obtain Synthesis gas；

The synthesis gas is sent into the conversion, decarburization unit carries out transformationreation so that the carbon monoxide in the synthesis gas Hydrogen and carbon dioxide are converted into, then hydrogen-rich gas is made after decarburization；

The high temperature mixed powder is sent into the calcium carbide and smelts unit, the hot method of oxygen, which is smelted, is made calcium carbide.

8. according to the method for claim 7, it is characterised in that the calcium based raw material includes carbide slag and quick lime, described The addition of carbide slag is the 20wt%-40wt% of the quick lime；The addition mass ratio of the calcium based raw material and the coal dust For 1.0-1.5:1.

9. according to the method for claim 7, it is characterised in that the temperature of the catalytic reforming is 700-900 DEG C, and pressure is 2-4MPa；The temperature of the transformationreation is 200-320 DEG C, and the catalyst of the transformationreation is urged for the Co-Mo systems wide temperature of resistant to sulfur Agent.

10. according to the method for claim 7, it is characterised in that methods described also includes step：

Coal and calcium based raw material are sent into the material processing unit so that coal is crushed to<1mm turns into coal dust so that the calcium base Raw material is crushed to<3mm；The coal is middle or low price coal.