Process method and system device for preparing high-quality oil gas by pyrolyzing low-caking coal
阅读说明：本技术 一种低粘结煤热解制备高品质油气的工艺方法及系统装置 (Process method and system device for preparing high-quality oil gas by pyrolyzing low-caking coal ) 是由 刘周恩 高士秋 李剑玲 李运甲 王超 余剑 于 2020-06-29 设计创作，主要内容包括：本发明提供了一种低粘结煤热解制备高品质油气的工艺方法及系统装置,所述的工艺方法包括：低粘结煤与氧化剂混合后经低温预氧化得到非粘结煤,非粘结煤通过分段升温热解制备得到所述的高品质油气。所述的系统装置包括依次连接的预氧化装置和热解反应装置；所述的热解反应装置内部沿物料流向分为依此连接的至少两级热解区。(The invention provides a process method and a system device for preparing high-quality oil gas by pyrolyzing low-caking coal, wherein the process method comprises the following steps: and the low-caking coal and the oxidant are mixed and then are subjected to low-temperature pre-oxidation to obtain non-caking coal, and the non-caking coal is subjected to segmented heating pyrolysis to prepare the high-quality oil gas. The system device comprises a pre-oxidation device and a pyrolysis reaction device which are connected in sequence; the interior of the pyrolysis reaction device is divided into at least two stages of pyrolysis areas which are connected in turn along the material flow direction.)
1. A process method for preparing high-quality oil gas by pyrolyzing low-caking coal is characterized by comprising the following steps:
and the low-caking coal and the oxidant are mixed and then are subjected to low-temperature pre-oxidation to obtain non-caking coal, and the non-caking coal is subjected to segmented heating pyrolysis to prepare the high-quality oil gas.
2. The process method according to claim 1, wherein the process method specifically comprises the steps of:
mixing low-caking coal with an oxidant, performing low-temperature pre-oxidation to break viscosity to obtain non-caking coal, heating the non-caking coal to a low-temperature pyrolysis temperature, generating low-temperature pyrolysis gas and obtaining low-oxygen non-caking coal;
(II) heating the low-oxygen non-caking coal obtained in the step (I) to a medium-temperature pyrolysis temperature to generate medium-temperature pyrolysis gas and obtain medium-temperature semicoke;
and (III) heating the warm semicoke obtained in the step (II) to a high-temperature pyrolysis temperature to generate high-temperature pyrolysis gas and obtain coke.
3. The process of claim 2, wherein in step (i), the low-caking coal has a caking index of 80 or less;
preferably, the oxidant is one or a combination of at least two of air, potassium permanganate, ozone or potassium carbonate;
preferably, the caking index of the non-caking coal is less than or equal to 5;
preferably, the low-temperature pre-oxidation temperature is 50-200 ℃;
preferably, the low-temperature pyrolysis gas comprises CO2And water vapor.
4. A process according to claim 2 or claim 3, wherein step (i) further comprises: under a closed anaerobic environment, introducing a deoxidizing agent material into the non-caking coal subjected to low-temperature pre-oxidation to remove residual oxidizing agents;
preferably, the deoxygenator material includes nitrogen or water.
5. The process of any one of claims 2 to 4, wherein in step (I), the low-temperature pyrolysis temperature is 200 to 300 ℃;
preferably, the heating rate of the low-temperature pyrolysis stage is 10-40 ℃/min;
preferably, the temperature is raised to the low-temperature pyrolysis temperature and then is kept for 10-30 min.
6. The process according to any one of claims 2 to 5, wherein in the step (II), the medium-temperature pyrolysis temperature is 300 to 600 ℃;
preferably, the temperature rise rate of the medium-temperature pyrolysis stage is 10-40 ℃/min;
preferably, heating to the medium-temperature pyrolysis temperature and then preserving heat for 10-30 min;
preferably, the medium-temperature pyrolysis gas comprises light tar and methane;
preferably, the medium-temperature pyrolysis gas is dedusted and condensed to obtain tar and pyrolysis gas;
preferably, the asphaltene component in the tar accounts for less than or equal to 40 wt%.
7. The process of any one of claims 2 to 6, wherein in step (III), the pyrolysis temperature is 600 to 900 ℃;
preferably, the heating rate of the high-temperature pyrolysis stage is 10-40 ℃/min;
preferably, heating to a high-temperature pyrolysis temperature and then preserving heat for 10-30 min;
preferably, the high-temperature pyrolysis gas is dedusted and condensed to obtain tar and pyrolysis gas;
preferably, the asphaltene component in the tar is less than or equal to 40 wt%.
8. The system device for preparing high-quality oil gas by pyrolyzing low-caking coal is characterized by comprising a pre-oxidation device and a pyrolysis reaction device which are sequentially connected;
the interior of the pyrolysis reaction device is divided into at least two stages of pyrolysis areas which are connected in turn along the material flow direction.
9. The system device according to claim 8, wherein an oxidant removing device is arranged on a connecting pipeline between the pre-oxidation device and the pyrolysis reaction device;
preferably, a non-caking coal outlet of the oxidant removing device is connected with the pyrolysis reaction device, an oxidant residue outlet of the oxidant removing device is respectively and independently connected with the residue recovery device and the residue treatment discharge device, and oxidant residues and deoxidant material residues separated by the oxidant removing device enter the residue recovery device for recycling or enter the residue treatment discharge device for treatment and then are discharged;
preferably, the outlet of the residue recovery device is respectively and independently connected with the pre-oxidation device and the oxidant removal device, the oxidant residue collected by the residue recovery device flows back to the pre-oxidation device for recycling, and the deoxidant material residue collected by the residue recovery device flows back to the oxidant removal device for recycling.
10. The system device according to claim 8 or 9, wherein the interior of the pyrolysis reaction device is divided into a low-temperature pyrolysis zone, a medium-temperature pyrolysis zone and a high-temperature pyrolysis zone which are connected in turn along the material flow direction;
preferably, the low-temperature pyrolysis zone is externally connected with a low-temperature pyrolysis gas treatment and discharge device;
preferably, the low-temperature pyrolysis gas treatment and discharge device comprises a first dust remover and a chimney which are sequentially connected along the gas flow direction;
preferably, the first dust remover is a sedimentation type dust remover;
preferably, the medium-temperature pyrolysis zone and the high-temperature pyrolysis zone are both externally connected with the pyrolysis gas treatment device;
preferably, the pyrolysis gas treatment device comprises a second dust remover and a condenser which are sequentially connected along the gas flow direction;
preferably, the second dust remover is a gas-solid separation dust remover.
Technical Field
The invention belongs to the technical field of coal utilization, and relates to a process method and a system device for preparing high-quality oil gas by pyrolyzing low-caking coal.
Background
Caking coal is an important coal resource, particularly high-caking coal (G is more than or equal to 80), which is very important coal for coking, but weak-caking coal (G is less than 80) cannot be used for coking and can only be used for combustion heating, gasification to provide coal gas or pyrolysis stripping gas. If the catalyst is used for pyrolysis oil extraction gas, important chemical products such as tar, coal gas, semicoke or coke can be obtained. Therefore, a considerable part of low-caking coal is used in the pyrolysis industry, but the existing pyrolysis technology has the key technical problems of low pyrolysis oil gas yield, poor quality, unstable system operation and the like, and particularly caking coal is easy to coke and block a furnace, the system operation stability is poor, and production accidents are easy to cause in severe cases.
In order to solve the problems, the patent CN102212378B develops an inner member pyrolysis reactor, which can greatly improve the yield of pyrolysis oil gas, reduce the content of asphaltene in tar to a certain extent, improve the yield of pyrolysis gas and the content of light organic gas components such as hydrogen, methane and the like in the pyrolysis gas to a certain extent, reduce the dust content of oil gas products through the adsorption and dust removal effect of solid materials when the gas materials flow in the solid materials in the inner member pyrolysis reactor, and greatly improve the quality of the oil gas products; meanwhile, non-caking coal is doped into caking coal to reduce caking property of the fed coal, reduce coking and furnace plugging frequency and degree, and improve system operation stability. However, the technology basically adopts one-stage high-temperature pyrolysis, which can cause secondary pyrolysis of light organic components such as tar and methane in coal gas, so that the tar amount is reduced, the asphaltene content of the tar is high, the content of the light organic components such as methane and hydrogen in the pyrolysis coal gas is low, the oil gas quality needs to be further improved, the caking property of the fed coal can be reduced to a certain degree by doping non-caking coal into the caking coal, but the caking property of the fed coal cannot be completely eliminated, the material is easy to coke, and a large amount of non-caking coal needs to be specially prepared and consumed.
Patent CN102120936A adopts efflux preoxidation pyrolysis fluidized bed gasification technique, and this technique adopts high-speed fluidic mode to spout the material into fluidized bed reactor, and the coal is the oxidation pyrolysis in advance at efflux in-process, makes the quick pyrolysis of coal solid particle become the semicoke to coal and semicoke granule are blown away under strong air current effect, and this patent can make the caking coal gasification in the gasifier effectively, and has avoided the stifled stove of coking. However, the pre-oxidation of the technology is mainly to remove combustible components in all volatile components and a bonding layer on the surface of semi-coke particles through the reaction of oxygen in a gasifying agent at high temperature, and break up the semi-coke particles through high-speed airflow, so that the materials are difficult to coke and block the furnace. However, volatile components volatilized out are all changed into synthetic gas (dry gas components are mainly carbon dioxide, carbon monoxide and a small amount of hydrogen) instead of pyrolysis gas with high hydrogen and methane contents, and tar components are all damaged, so that high-quality oil and gas components of coal cannot be extracted.
Therefore, the research on how to effectively pyrolyze the low-metamorphic caking coal to prepare the high-quality oil gas and solve the problem of coking and furnace blockage so as to improve the operation stability has very important practical significance.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a process method and a system device for preparing high-quality oil gas by pyrolyzing low-caking coal. Meanwhile, the pyrolysis is carried out by adopting a segmented temperature rise pyrolysis mode, so that the secondary pyrolysis of the components in a high-temperature pyrolysis section is avoided, the tar yield is improved, the asphaltene content is reduced, the contents of organic components such as methane in pyrolysis gas are improved, and the quality of pyrolysis oil gas products is improved.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a process for preparing high quality oil gas by pyrolyzing low-caking coal, wherein the process comprises:
and the low-caking coal and the oxidant are mixed and then are subjected to low-temperature pre-oxidation to obtain non-caking coal, and the non-caking coal is subjected to segmented heating pyrolysis to prepare the high-quality oil gas.
The invention firstly adopts the low-temperature preoxidation viscosity breaking process, the caking property of the coal is broken, the coking and furnace blockage phenomenon which occurs when the caking coal is pyrolyzed is eliminated, the system operation stability is improved, and a large amount of non-caking coal is not required to be prepared and consumed. Meanwhile, different from high-temperature preoxidation viscosity breaking, low-temperature preoxidation viscosity breaking is adopted, coal can not be pyrolyzed under the condition of low-temperature preoxidation viscosity breaking, volatile components can not be released, semicoke or coke can not be produced, and the volatile components and the surfaces of semicoke particles can not be oxidized and gasified, so that the loss of tar and pyrolysis gas and the reduction of quality can not be caused.
The pyrolysis is carried out by adopting a segmented temperature rise mode, so that the tar yield is improved, the asphaltene content is reduced, the contents of organic components such as methane in pyrolysis gas are improved, and the quality of pyrolysis oil gas products is improved. The invention relates to a sectional heating pyrolysis process, which adopts a sectional heating pyrolysis mode from low to high, namely, low-temperature pyrolysis is firstly carried out to realize decarboxylation deoxidation reaction, the coal oxygen content is reduced or removed to eliminate the influence of oxygen on the produced oil gas product, then intermediate-temperature pyrolysis is carried out, tar components with low asphaltene content and pyrolysis coal gas rich in light organic components such as methane are extracted, secondary cracking during subsequent high-temperature pyrolysis is prevented, and finally high-temperature pyrolysis is carried out to dissolve residual volatile components out as much as possible to generate hydrogen-rich pyrolysis gas, thereby improving the yield and the quality of the pyrolysis coal gas. The staged heating pyrolysis can be two-stage or more staged heating pyrolysis.
In addition, it is particularly emphasized that the process provided by the invention is not only suitable for low-deterioration caking coal, but also can be high-caking coal, and can also be other caking materials, such as biomass and the like.
As a preferred technical scheme of the invention, the process method specifically comprises the following steps:
mixing low-caking coal with an oxidant, performing low-temperature pre-oxidation to break viscosity to obtain non-caking coal, heating the non-caking coal to a low-temperature pyrolysis temperature, generating low-temperature pyrolysis gas and obtaining low-oxygen non-caking coal;
(II) heating the low-oxygen non-caking coal obtained in the step (I) to a medium-temperature pyrolysis temperature to generate medium-temperature pyrolysis gas and obtain medium-temperature semicoke;
and (III) heating the warm semicoke obtained in the step (II) to a high-temperature pyrolysis temperature to generate high-temperature pyrolysis gas and obtain coke.
Firstly, the low-temperature preoxidation visbreaking process is adopted to reduce or remove the viscidity of low-metamorphic caking coal so as to prevent coking and furnace blockage, thereby improving the operation stability; and then pyrolyzing the viscosity-broken low-metamorphic coal in a pyrolysis reaction device in a sectional heating mode to prepare an oil gas product so as to improve the quality of the oil gas product prepared by pyrolysis.
The low-temperature pre-oxidation viscosity breaking process adopted by the invention is different from the high-temperature pre-oxidation viscosity breaking process, the high-temperature pre-oxidation viscosity breaking process is realized by gasifying volatile components and semicoke particles of coal, and the low-temperature pre-oxidation viscosity breaking process adopted by the invention is realized by attacking branched chains or bridged bonds of aliphatic hydrocarbon carbon in coal macromolecules by oxygen atoms to form oxygen-containing functional groups, so that the branched chains or the bridged bonds of the aliphatic hydrocarbon carbon fall or are broken to break coal colloids, and the coal colloids are not sticky. The reaction principle is as follows: during low-temperature pre-oxidation, oxygen molecules attack fat branched chains and bridge bond carbon atoms of aliphatic hydrocarbon carbon in a coal macromolecular structure to form oxygen-containing functional groups, so that the oxygen-containing functional groups fall off and are broken, the aliphatic hydrocarbon carbon in the coal is reduced, and colloidal substances playing a binding role in the coal are reduced or even eliminated, so that the cohesive coal loses viscosity and becomes mixed oxidant non-cohesive coal mixed with a small amount of oxidant residues.
In the process of the segmented temperature rise pyrolysis, three-segment temperature rise pyrolysis is preferably adopted, and the three-segment temperature rise pyrolysis comprises low-temperature pyrolysis, medium-temperature pyrolysis and high-temperature pyrolysis which are sequentially carried out.
In the low-temperature pyrolysis stage, oxygen-containing functional groups such as carboxyl and hydroxyl in the non-caking coal are heated and begin to decompose for decarboxylation and deoxidation, the non-caking coal becomes the low-oxygen-containing functional group non-caking coal and releases low-temperature pyrolysis gas mainly comprising carbon dioxide and water, and the low-temperature pyrolysis gas is discharged through a low-temperature pyrolysis gas treatment and discharge device.
In the medium-temperature pyrolysis stage, the non-caking coal with low oxygen-containing functional groups is subjected to medium-temperature pyrolysis, most of volatile matters in the low-oxygen non-caking coal are cracked into medium-temperature pyrolysis gas rich in light tar components, methane and other light organic non-condensable gases and discharged from the pyrolysis reaction device, and the low-oxygen non-caking coal with low oxygen-containing functional groups after the volatile matters are released becomes medium-temperature semicoke.
In the high-temperature pyrolysis stage, the non-caking coal is completely changed into the medium-temperature semicoke, the medium-temperature pyrolysis gas is completely discharged from the pyrolysis reaction device, the temperature is rapidly increased to the high-temperature pyrolysis section, under the action of high temperature, a small amount of residual volatile components in the medium-temperature semicoke are volatilized to be changed into high-temperature pyrolysis gas with high asphaltene content and rich hydrogen and coke (the high-temperature semicoke if the temperature is not high enough) and discharged, and the coke is discharged as a product and then is collected, treated and utilized in a centralized manner.
In a preferred embodiment of the present invention, in step (I), the caking index of the low-caking coal is not more than 80, for example, 40, 45, 50, 55, 60, 65, 70, 75 or 80, but not limited to the values listed, and other values not listed in the range of the values are also applicable.
The caking index determination is to mix a test coal sample and a special smokeless coal sample (the special smokeless coal produced by Ningxia Ru osmunda ditch mine in China is taken as a standard coal sample) with certain quality under a specified condition, rapidly heat the mixture to form coke, perform strength test on the obtained coke block in a rotary drum with a certain specification, and express the caking capacity of the coal sample by the wear resistance of the coke block, namely the size of the breaking resistance. The caking index is a key index for judging caking property and coking property of coal. The caking index defined by the invention is determined by using a method for determining the caking index of the bituminous coal in GB/T5447-1977.
Preferably, the oxidant is one or a combination of at least two of air, potassium permanganate, ozone and potassium carbonate.
In the present invention, the oxidant may be a gaseous oxidant, a solid oxidant or a liquid oxidant, or an oxidant in a multi-phase state such as gas-solid mixture, or an oxidant with catalytic oxidation, or a single oxidant, or a mixture of multiple oxidants, such as air, potassium permanganate, ozone, or a mixture of air and potassium carbonate.
Preferably, the non-caking coal has a caking index of < 5, and may be, for example, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4 or 4.5, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.
Preferably, the low-temperature pre-oxidation temperature is 50 to 200 ℃, for example, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃ or 150 ℃, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
In the invention, the low-temperature pre-oxidation temperature is adopted to be as far as possible not to exceed the minimum critical temperature of decarboxylation deoxidation of the coal for removing the oxygen-containing functional groups.
Preferably, the low-temperature pyrolysis gas comprises CO2And water vapor.
As a preferred embodiment of the present invention, step (i) further comprises: and under a closed anaerobic environment, introducing a deoxidizing agent material into the non-caking coal subjected to low-temperature pre-oxidation to remove residual oxidizing agents in the non-caking coal.
Preferably, the deoxygenator material includes nitrogen or water.
In the present invention, the deoxidizing agent material may be a gaseous material, a liquid material or a solid material, such as nitrogen or water, and mechanical or chemical methods such as vacuum pumping may also be used.
In a preferred embodiment of the present invention, in the step (I), the low-temperature pyrolysis temperature is 200 to 300 ℃, and may be, for example, 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃ or 300 ℃, but is not limited to the above-mentioned values, and other values not listed in the above-mentioned value range are also applicable.
In the invention, the adopted low-temperature pyrolysis temperature is between the minimum decarboxylation and deoxidation critical temperature of coal and the minimum critical temperature of light organic gases such as methane and the like which are obviously released when the coal is heated, and the specific temperature is determined according to the specific minimum decarboxylation and deoxidation critical temperature of the specific coal and the minimum critical temperature of the light organic gases such as methane and the like which are obviously released when the coal is heated.
Preferably, the temperature rise rate of the low-temperature pyrolysis stage is 10-40 ℃/min, such as 10 ℃/min, 15 ℃/min, 20 ℃/min, 25 ℃/min, 30 ℃/min, 35 ℃/min or 40 ℃/min, but not limited to the values listed, and other values not listed in the range of the values are also applicable.
In the invention, the heating rate should reach a constant temperature state as fast as possible to reduce the retention time of pyrolysis gas in the pyrolysis reaction device.
Preferably, the temperature is increased to the low-temperature pyrolysis temperature and then kept for 10-30 min, such as 10min, 12min, 14min, 16min, 18min, 20min, 22min, 24min, 26min, 28min or 30min, but not limited to the values listed, and other values not listed in the range of the values are also applicable.
In a preferred embodiment of the present invention, in the step (II), the medium-temperature pyrolysis temperature is 300 to 600 ℃, and may be, for example, 300 ℃, 320 ℃, 340 ℃, 360 ℃, 380 ℃, 400 ℃, 420 ℃, 440 ℃, 460 ℃, 480 ℃, 500 ℃, 520 ℃, 540 ℃, 560 ℃, 580 ℃ or 600 ℃, but is not limited to the above-mentioned values, and other values not listed in the above-mentioned range of values are also applicable.
In the present invention, the medium-temperature pyrolysis temperature is used at a temperature near the analytical temperature of the coal, i.e., the temperature at which the yield of tar is the highest.
Preferably, the temperature rise rate of the medium-temperature pyrolysis stage is 10-40 ℃/min, such as 10 ℃/min, 15 ℃/min, 20 ℃/min, 25 ℃/min, 30 ℃/min, 35 ℃/min or 40 ℃/min, but not limited to the values listed, and other values not listed in the range of the values are also applicable.
In the invention, the heating rate should reach a constant temperature state as fast as possible to reduce the retention time of pyrolysis gas in the pyrolysis reaction device.
Preferably, the temperature is increased to the mesophilic pyrolysis temperature and then maintained for 10-30 min, such as 10min, 12min, 14min, 16min, 18min, 20min, 22min, 24min, 26min, 28min or 30min, but not limited to the values listed, and other values not listed in the range of the values are also applicable.
Preferably, the medium-temperature pyrolysis gas comprises light tar and methane.
Preferably, the medium-temperature pyrolysis gas is dedusted and condensed to obtain tar and pyrolysis gas.
Preferably, the asphaltene component of the tar is less than or equal to 40 wt%, and can be, for example, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt% or 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt% or 40 wt%, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.
In a preferred embodiment of the present invention, in the step (iii), the pyrolysis temperature is 600 to 900 ℃, for example, 600 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃ or 900 ℃, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.
In the invention, the adopted high-temperature pyrolysis temperature is between the temperature at which the hydrogen yield is larger and the asphaltene content in the produced tar is not too high when the medium-temperature semicoke generated after the medium-temperature pyrolysis of the coal is subjected to high-temperature pyrolysis again.
Preferably, the temperature rise rate of the high-temperature pyrolysis stage is 10-40 ℃/min, such as 10 ℃/min, 15 ℃/min, 20 ℃/min, 25 ℃/min, 30 ℃/min, 35 ℃/min or 40 ℃/min, but not limited to the values listed, and other values not listed in the range of the values are also applicable.
In the invention, the heating rate should reach a constant temperature state as fast as possible to reduce the retention time of pyrolysis gas in the pyrolysis reaction device.
Preferably, the temperature is raised to the pyrolysis temperature and then kept for 10-30 min, such as 10min, 12min, 14min, 16min, 18min, 20min, 22min, 24min, 26min, 28min or 30min, but not limited to the values listed, and other values not listed in the range of the values are also applicable.
Preferably, the high-temperature pyrolysis gas is dedusted and condensed to obtain tar and pyrolysis gas.
Preferably, the asphaltene component of the tar is less than or equal to 40 wt%, and can be, for example, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt% or 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt% or 40 wt%, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.
In a second aspect, the invention provides a system device for preparing high-quality oil gas by pyrolyzing low-caking coal, which comprises a pre-oxidation device and a pyrolysis reaction device which are connected in sequence.
The interior of the pyrolysis reaction device is divided into at least two stages of pyrolysis areas which are connected in turn along the material flow direction.
As a preferable technical scheme of the invention, an oxidant removing device is arranged on a connecting pipeline between the pre-oxidation device and the pyrolysis reaction device.
Preferably, a non-caking coal outlet of the oxidant removing device is connected with the pyrolysis reaction device, an oxidant residue outlet of the oxidant removing device is respectively and independently connected with the residue recovery device and the residue treatment discharge device, and oxidant residues and deoxidant material residues separated by the oxidant removing device enter the residue recovery device for recycling or enter the residue treatment discharge device for treatment and then are discharged.
Preferably, the outlet of the residue recovery device is respectively and independently connected with the pre-oxidation device and the oxidant removal device, the oxidant residue collected by the residue recovery device flows back to the pre-oxidation device for recycling, and the deoxidant material residue collected by the residue recovery device flows back to the oxidant removal device for recycling.
As a preferable technical scheme of the invention, the interior of the pyrolysis reaction device is divided into a low-temperature pyrolysis area, a medium-temperature pyrolysis area and a high-temperature pyrolysis area which are connected in turn along the material flow direction.
Preferably, the low-temperature pyrolysis zone is externally connected with a low-temperature pyrolysis gas treatment and discharge device.
Preferably, the low-temperature pyrolysis gas treatment and discharge device comprises a first dust remover and a chimney which are sequentially connected along the gas flow direction.
Preferably, the first dust remover is a sedimentation type dust remover.
Preferably, the medium-temperature pyrolysis zone and the high-temperature pyrolysis zone are both externally connected with the pyrolysis gas treatment device.
Preferably, the pyrolysis gas treatment device comprises a second dust remover and a condenser which are connected in sequence along the gas flow direction.
Preferably, the second dust remover is a gas-solid separation dust remover.
Illustratively, the invention provides a specific structure of an optional system device, and the system device mainly comprises a pyrolysis reaction device, a low-temperature pyrolysis gas treatment discharge device, a pyrolysis gas treatment device, a pre-oxidation device, an oxidant removal device, a residue recovery device and a residue treatment discharge device.
The pyrolysis reaction device is mainly used for producing oil gas products by coal pyrolysis, is a multistage moving bed pyrolysis reactor and is divided into a low-temperature pyrolysis zone, a medium-temperature pyrolysis zone and a high-temperature pyrolysis zone which are sequentially communicated from top to bottom. A first inner member is arranged in the low-temperature pyrolysis zone, a second inner member is arranged in the medium-temperature pyrolysis zone, and a third inner member is arranged in the high-temperature pyrolysis zone. The coal inlet is positioned at the top of the low-temperature pyrolysis zone and is externally connected with a coal outlet of an oxidant removal device; the top wall of the first inner member is provided with a low-temperature pyrolysis gas outlet which is externally connected with a low-temperature pyrolysis gas treatment and discharge device. The top wall of the second inner component is provided with a medium-temperature pyrolysis gas outlet which is externally connected with a pyrolysis gas treatment device. The top wall of the third inner component is provided with a high-temperature pyrolysis gas outlet which is externally connected with a pyrolysis gas processing device, the bottom of the third inner component is provided with a coke outlet which is externally connected with a coke processing and storing system.
The low-temperature pyrolysis gas treatment and discharge device is mainly used for performing dust removal, cooling and other treatment on generated low-temperature pyrolysis gas and discharging the treated low-temperature pyrolysis gas out.
The pyrolysis gas treatment device is mainly used for removing dust from generated intermediate-temperature pyrolysis gas and high-temperature pyrolysis gas, cooling and separating the intermediate-temperature pyrolysis gas and the high-temperature pyrolysis gas to obtain tar products and pyrolysis gas products, and specifically comprises a gas-solid separation dust remover, a pyrolysis gas condensation liquefying device, a liquid-gas separation device and a tar dehydration purifying device which are sequentially connected along the gas flow direction, wherein an intermediate-temperature pyrolysis gas inlet of the gas-solid separation dust remover is connected with an intermediate-temperature pyrolysis gas outlet of a second inner member, a high-temperature pyrolysis gas inlet of the gas-solid separation dust remover is connected with a high-temperature pyrolysis gas outlet of a third inner member, a tar outlet of the tar dehydration purifying device is connected with a tar storage system, and a pyrolysis gas outlet of the liquid-gas separation device.
The pre-oxidation device is mainly used for reducing or removing the viscosity of the caking coal and specifically comprises combined equipment consisting of a slurry bed reactor and a liquid-solid separation device which are sequentially connected, wherein a coal inlet of the slurry bed reactor is connected with a coal supply system, an oxidant inlet of the slurry bed reactor is connected with an oxidant supply system, an oxidant residue inlet of the slurry bed reactor is connected with an oxidant residue outlet of a residue recovery device, and a coal outlet of the liquid-solid separation device is connected with a coal inlet of the oxidant removal device.
The oxidant removing device is mainly used for removing oxidant residues in non-caking coal and specifically comprises a coal washing device, a screening device and a drying device which are sequentially connected to form combined equipment, wherein a deoxidizing agent material inlet of the coal washing device is connected with a deoxidizing agent material supply system, a coal inlet of the coal washing device is connected with a coal outlet of the pre-oxidation device, a coal outlet of the drying device is connected with a coal inlet of the first inner member, a residue outlet of the screening device is respectively connected with a feed inlet of the residue recovery device and a feed inlet of the residue treatment discharge device, and a deoxidizing agent material residue inlet of the coal washing device is connected with a deoxidizing agent material residue outlet of the residue recovery device.
The residue recovery device is mainly used for separating and purifying a mixture of oxidant residues and deoxidizing agent material residues to meet the requirement that the oxidant residues and the deoxidizing agent material residues can be recycled, and is a solution concentration device.
The residue treatment and discharge device is mainly used for treating and discharging the unusable residues, and the feed inlet of the residue treatment and discharge device is connected with the residue outlet of the oxidant removal device.
The system refers to an equipment system, or a production equipment.
Compared with the prior art, the invention has the beneficial effects that:
the invention firstly adopts the low-temperature preoxidation viscosity breaking process, the caking property of the coal is broken, the coking and furnace blockage phenomenon which occurs when the caking coal is pyrolyzed is eliminated, the system operation stability is improved, and a large amount of non-caking coal is not required to be prepared and consumed. Meanwhile, different from high-temperature preoxidation viscosity breaking, low-temperature preoxidation viscosity breaking is adopted, coal can not be pyrolyzed under the condition of low-temperature preoxidation viscosity breaking, volatile components can not be released, semicoke or coke can not be produced, and the volatile components and the surfaces of semicoke particles can not be oxidized and gasified, so that the loss of tar and pyrolysis gas and the reduction of quality can not be caused. The pyrolysis is carried out by adopting a segmented temperature rise mode, so that the tar yield is improved, the asphaltene content is reduced, the contents of organic components such as methane in pyrolysis gas are improved, and the quality of pyrolysis oil gas products is improved.
Drawings
Fig. 1 is a schematic structural diagram of a system apparatus according to embodiment 1 of the present invention;
fig. 2 is a schematic structural diagram of a pyrolysis reaction apparatus provided in embodiment 1 of the present invention.
Wherein, 1-a pyrolysis reaction device; 11-a low temperature pyrolysis zone; 12-medium temperature pyrolysis zone; 13-a high temperature pyrolysis zone; 14-a first inner member; 15-a second inner member; 16-a third inner member; 2-a low-temperature pyrolysis gas treatment and discharge device; 3-pyrolysis gas treatment device; 4-a pre-oxidation device; 5-an oxidant removal device; 6-a residue recovery unit; 7-residue treatment discharge device.
Detailed Description
It is to be understood that in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be taken as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
It should be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "disposed," "connected" and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
In one embodiment, the invention provides a process for preparing high-quality oil gas by pyrolyzing low-caking coal, which comprises the following steps:
(1) mixing low-caking coal with a caking index of less than or equal to 80 with an oxidant, and performing low-temperature pre-oxidation viscosity breaking treatment at 50-200 ℃ to obtain non-caking coal, wherein the oxidant is one or a combination of at least two of air, potassium permanganate, ozone or potassium carbonate; the caking index of the non-caking coal is less than or equal to 5;
(2) introducing a deoxidizing agent material into the non-caking coal subjected to low-temperature pre-oxidation in a closed anaerobic environment, and removing residual oxidant and deoxidizing agent materials in the non-caking coal, wherein the deoxidizing agent material comprises nitrogen or water;
(3) respectively returning the separated oxidant residues and deoxidant material residues to the step (1) and the step (2) for recycling, and if the oxidant residues and the deoxidant material residues cannot be recycled again, introducing the oxidant residues and the deoxidant material residues into a residue
(4) heating the non-caking coal without the oxidant residues to 200-300 ℃ at a heating rate of 10-40 ℃/min, then preserving the temperature for 10-30 min, carrying out decarboxylation and deoxidation on oxygen-containing functional groups such as carboxyl and hydroxyl in the non-caking coal by thermal decomposition, generating low-temperature pyrolysis gas and obtaining the low-oxygen-containing functional group low-oxygen non-caking coal, wherein the low-temperature pyrolysis gas comprises CO2And water vapor;
(5) after low-temperature pyrolysis gas is exhausted, heating the low-oxygen non-caking coal to 300-600 ℃ at a heating rate of 10-40 ℃/min, and then preserving heat for 10-30 min, wherein the low-oxygen non-caking coal is subjected to medium-temperature pyrolysis, most of volatile matters in the low-oxygen non-caking coal are cracked to generate medium-temperature pyrolysis gas and obtain medium-temperature semicoke, and the medium-temperature pyrolysis gas comprises light tar and methane;
(6) heating the medium-temperature semi-coke to 600-900 ℃ at a heating rate of 10-40 ℃/min, then preserving the heat for 10-30 min, volatilizing a small amount of residual volatile matters in the medium-temperature semi-coke to generate high-temperature pyrolysis gas and obtain coke;
(7) and (3) discharging the medium-temperature pyrolysis gas obtained in the step (5) and the high-temperature pyrolysis gas obtained in the step (6) out of the pyrolysis reaction device 1, then feeding the medium-temperature pyrolysis gas and the high-temperature pyrolysis gas into a pyrolysis
In another embodiment, the invention provides a system device for preparing high-quality oil gas by pyrolyzing low-caking coal, which is shown in fig. 1 and comprises a
An
The inside of the pyrolysis reaction device 1 is divided into a low-
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