Internal heating type rotary furnace low-order pulverized coal pyrolysis system

Abstract

The utility model relates to a low-order pulverized coal pyrolysis system of an internal heating type rotary furnace. The low-order pulverized coal pyrolysis system consists of a heat carrier system, a pulverized coal drying system, a pulverized coal pyrolysis system, a waste heat recovery system, a semicoke cooling system and an oil gas recovery system, a hot blast stove unit is adopted to produce a hot gas carrier for pulverized coal drying and pulverized coal pyrolysis, a rotary furnace adopting a hot flue gas carrier is adopted to dry pulverized coal, an internal heating rotary furnace adopting a hot gas carrier is adopted to pyrolyze pulverized coal, a coke particle moving bed is adopted to separate high-temperature oil gas from dust, and a rotary furnace adopting a dividing wall heat exchanger and a flue gas cold carrier is adopted to cool semi-coke. The system heat efficiency is improved, the energy consumption of the system is reduced, the amount of coal dust brought into an oil gas recovery system by the raw gas is reduced, the yield of a coal tar product and the content of effective components, especially H2, CO and CH4, in pyrolysis gas are improved, and the heat value of the product gas is 3500-4500 kcal / Nm < 3 >.

Description

Technical Field

[0001] The utility model relates to the technical field of coal chemical industry, and in particular to a process system which uses low-grade pulverized coal as raw material, adopts an internal heating rotary furnace for pyrolysis and upgrading, and produces anhydrous semi-coke, high calorific value coal gas and high-yield coal tar. Background Art

[0002] my country is rich in low-rank coal resources. As the main coal producing areas move westward, the output of low-rank coal will increase in the future. However, currently more than 90% of low-rank coal is directly burned for power generation, industrial boilers and civilian fuel, which has low resource utilization efficiency and high environmental protection costs. On the one hand, low-rank coal usually has the characteristics of high oxygen content, high moisture content, poor stability and low calorific value; on the other hand, in the large-scale mechanized coal mining process, the yield of 0-30mm pulverized coal accounts for about 60% to 70%, which greatly limits the utilization of low-rank coal.

[0003] Low-rank coal fractionation technology has low water consumption, low emissions, high energy efficiency, and can maximize the use of high-value components and chemical energy of raw coal. It is the most reasonable development direction at present. Solving the pyrolysis problem of low-rank pulverized coal, reducing its moisture and volatile content, improving its calorific value and thermal stability, and recovering coal tar and coal gas will not only help to make up for part of the gap in oil and natural gas resources, but also improve the utilization level of low-rank coal in my country and promote the development of my country's economy.

[0004] At present, most of the processes involving pyrolysis and upgrading of low-rank coal at home and abroad are not mature enough and are basically in the test or demonstration stage. The main technical difficulties are: the amount of dust in coal tar is high and difficult to separate, the yield of coal tar is low, the calorific value of coal gas is low, and semi-coke needs to be quenched by water, resulting in high energy consumption of the system.

[0005] The rotary kiln pyrolysis technology is recognized as a process with low coal tar dust content and high coal tar yield, but there is room for further improvement. The current mainstream rotary kiln pyrolysis uses an externally heated rotary kiln, and is a three-stage furnace that includes drying, pyrolysis and cooling. The difference between the various related processes lies only in the source and recovery of heat in the process.

[0006] The Chinese patent application with publication number CN 1066459A discloses "a multi-stage rotary furnace gas heat carrier internal and external heating low-medium temperature rapid pyrolysis process". Coal drying, pyrolysis and cooling are carried out in three rotary furnaces respectively, using hot flue gas internal heating drying, external heating pyrolysis, internal heating carbonization heat processing, and water spraying on a vibrating screen to quench coke. Among them, in the carbonization furnace, the semi-coke is further pyrolyzed to generate granular coke by internal heating to 800-850℃, and the generated high-temperature mixed gas is introduced into the pyrolysis heating furnace. The raw coal particle size treated by this process is 3-30mm, and it cannot solve the pyrolysis problem of pulverized coal with a particle size of 0-3mm.

[0007] The Chinese invention patent with the authorization announcement number CN 103074095 B discloses "a coal pyrolysis system", which includes: a drying rotary kiln for drying raw coal to obtain dry material; a pyrolysis rotary kiln for pyrolyzing the dry material formed by the drying rotary kiln to obtain hot semi-coke; a heating rotary kiln for heating and refluxing the first part of the hot semi-coke formed by the pyrolysis rotary kiln; and a cooling device for cooling the second part of the hot semi-coke formed by the pyrolysis rotary kiln to obtain product semi-coke. The main purpose of this coal pyrolysis system is to add a heating rotary kiln between the drying rotary kiln and the pyrolysis rotary kiln, so that the hot semi-coke part generated by the pyrolysis rotary kiln is heated by the heating rotary kiln and then refluxed and mixed with the dry material dried by the drying rotary kiln, so as to further heat the dry material, and realize the continuous operation of the low-metamorphic coal pyrolysis process through the sequential operation of the drying rotary kiln, the pyrolysis rotary kiln, the heating rotary kiln and the cooling device.

[0008] The Chinese patent application with publication number CN 102250633 A discloses "a method for upgrading lignite using an externally heated rotary furnace". Drying, carbonization and cooling are carried out in three rotary furnaces respectively, and hot flue gas is used for drying, externally heated pyrolysis and dry quenching. The dry quenching process adopts the rotary furnace dry quenching process, and the semi-coke is indirectly cooled in the furnace. The cooling medium can be selected by cooling circulating water spray cooling, or inert gas can be selected to contact and heat exchange with the red-hot red coke in the furnace. The inert gas does not react or burn with the semi-coke, and it is relatively stable under high temperature conditions and does not decompose. Since the heat contained in the pyrolysis semi-coke accounts for 25%-45% of the total load of drying and distillation, and the inert gas after cooling the semi-coke is not heat recovered, the energy efficiency of the entire system is not high.

[0009] The Chinese patent application with publication number CN 101805625 A discloses "a method for preparing semi-coke by thermal cracking raw coal in an externally heated horizontal rotary carbonization furnace". The horizontal rotary carbonization furnace is divided into two parts: a drying section and a carbonization section. The heating method of the rotary carbonization furnace is an external heating form of a jacket. The hot air at the outlet of the carbonization furnace retorting section returns to the drying section of the carbonization furnace for heating. The drying section and the retorting section are indirectly heated, and the heat is recycled. The semi-coke quenching treatment adopts two dry quenching processes. One is that the semi-coke is sent to a rotary cooler for indirect cooling under air-tight conditions, and the cooling medium is circulating water spray cooling; the other is that in the rotary dry quenching furnace, inert gas is used for heat exchange cooling with red-hot red coke. The problem with this method is that the heat released during the semi-coke quenching process is also not well utilized, and the system energy efficiency is not high. At the same time, the particle size of its raw coal is 3-80mm, which is not suitable for the pyrolysis of 0-3mm pulverized coal.

[0010] The Chinese invention patent with the authorization announcement number CN 104789244 B discloses a method for producing anthracite by pyrolysis of pulverized coal rotary furnace. The production system includes a pulverized coal dust removal rotary drying furnace system, an external heating rotary furnace pyrolysis system with coal gas circulation, a rotary cooling passivation system with heat recovery, and an oil and gas recovery system. The dust removal rotary drying furnace system is heated to 110-280°C to remove coal dust with a particle size of less than 0.2mm in the pulverized coal; the recovered dry water is sent to the downstream spiral cooler as water for cooling and humidifying anthracite, and the separated coal dust is sent to the gas generation system to produce fuel coal gas. The dust-removed coal is sent to the downstream rotary pyrolysis system for pyrolysis, and the high-temperature anthracite produced is cooled, passivated at medium and low temperatures, cooled by a spiral cooler, and humidified by water spraying before being sent out; the high-temperature oil and gas produced enters the oil and gas recovery system to obtain coal tar, pyrolysis water, and coal gas. Part of the produced pyrolysis coal gas is preheated and circulated back to the pyrolysis furnace, and the remaining part is sent out. However, with the increasing efforts in environmental protection, the coal-fired hot air furnace used in this method is no longer in line with current industrial policies, and its oil and gas dust removal system still needs to be improved. Summary of the invention

[0011] The utility model provides an internal heating type rotary furnace low-grade pulverized coal pyrolysis system, adopts a hot blast furnace group to produce hot coal gas carriers for pulverized coal drying and pulverized coal pyrolysis, adopts a rotary furnace with hot flue gas carriers to achieve pulverized coal drying, adopts an internal heating type rotary furnace with hot coal gas carriers to achieve pulverized coal pyrolysis, adopts a coke particle moving bed to separate high-temperature oil gas from dust, adopts a partition heat exchanger and a rotary furnace with flue gas cooling carriers to cool semi-coke, improves the system thermal efficiency, reduces the system energy consumption, reduces the amount of coal dust brought into the oil and gas recovery system by raw coal gas, improves the yield of coal tar products and the content of effective components in the pyrolysis coal gas, especially H2, CO and CH4, and the calorific value of the product coal gas is 3500-4500 kcal / Nm 3 .

[0012] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0013] A low-grade pulverized coal pyrolysis system of an internally heated rotary furnace comprises a heat carrier system, a pulverized coal drying system, a pulverized coal pyrolysis system, a waste heat recovery system, a semi-coke cooling system and an oil and gas recovery system; the heat carrier system is composed of an air blower, a hot blast furnace group and a flue gas heat exchanger connected in sequence; the pulverized coal drying system comprises a raw coal conveyor, a raw coal bin, a raw coal weighing machine, a raw coal feeder and a drying rotary furnace connected in sequence, and also comprises a flue gas dust removal device, a chimney and a pulverized coal forming device; the drying rotary furnace is an internally heated furnace of a hot flue gas heat carrier, and the hot flue gas inlet of the drying rotary furnace is connected to the hot flue gas outlet of the flue gas heat exchanger; the drying rotary furnace is connected to the flue gas dust removal device and the chimney in sequence through a flue gas pipeline, and the flue gas dust removal device is connected to the hot flue gas outlet of the flue gas heat exchanger through a flue gas duct The dust and ash conveying pipeline is connected to the coal powder molding device; the pulverized coal pyrolysis system includes a dry coal conveyor, a dry coal buffer bin, a dry coal feeder and a pyrolysis rotary furnace connected in sequence, and also includes a coke particle screener; the flue gas dust removal device is connected to the dry coal conveyor through a dust and ash removal pipeline, and the coal powder molding device is connected to the dry coal conveyor through a briquette conveying pipeline; the pyrolysis rotary furnace is an internal heating furnace with hot coal gas heat carrier, and the hot coal gas inlet of the pyrolysis rotary furnace is connected to the hot blast furnace group through a hot coal gas pipeline; the semi-coke cooling system includes a coke powder buffer bin, a coke particle moving bed, a semi-coke feeder, a cooling rotary furnace, a cooling semi-coke conveyor, a passivation air intake fan, a flue gas condenser and a coke discharge dust removal device; the discharge port of the pyrolysis rotary furnace is connected to the coke powder buffer bin through a coke particle screener The discharge ports of the flushing bin and the coke particle moving bed, the coke powder buffer bin and the coke particle moving bed are all connected to the cooling rotary kiln through the semi-coke feeder, and the discharge port of the cooling rotary kiln is connected to the semi-coke processing system through the cooling semi-coke conveyor; the waste heat recovery system includes a partition heat exchanger and a steam drum; the coke powder buffer bin and the coke particle moving bed are both provided with a partition heat exchanger; the partition heat exchanger is connected to the steam drum through a steam pipe and a hot water pipe, and the steam drum is also connected to an external steam delivery pipe; the discharge port of the cooling rotary kiln is connected to the coke exhaust and dust removal device through a flue gas pipe, the coke exhaust and dust removal device is connected to the coal powder forming device through a dust removal ash delivery pipe, and is connected to the chimney through an external flue gas pipe; the flue gas pipe downstream of the flue gas dust removal device is also connected to the cooling rotary kiln through a flue gas delivery pipe The flue gas inlet is provided with an air inlet, a passivation air intake fan and a flue gas condenser on the flue gas conveying pipeline; the oil and gas recovery system comprises a direct cooling tower, an intercooling tower, an electric tar precipitator and a gas fan which are connected in sequence, and the gas fan is also connected to an external gas delivery pipeline and a fuel gas inlet and a heat carrier gas inlet of a hot blast furnace group; the oil and gas recovery system also comprises a tar ammonia water separator; the coke particle moving bed is connected to the direct cooling tower through a raw gas pipeline; the liquid phase outlets of the direct cooling tower, the intercooling tower and the electric tar precipitator are all connected to the inlet of the tar ammonia water separator, and the tar ammonia water separator is also connected to the direct cooling tower through a circulating ammonia water pipeline, connected to an external tar delivery pipeline through a tar outlet, and connected to a dust ash conveying pipeline downstream of the coke discharge and dust removal device through a tar residue pipeline.

[0014] Furthermore, the semi-coke cooling system also includes an accident quenching trolley, an accident coke conveyor and an accident coke bin connected in sequence; the feed end of the accident quenching trolley is simultaneously connected to the discharge ends of the coke powder buffer bin and the coke particle moving bed; the discharge port of the accident coke bin is connected to the semi-coke processing system through a semi-coke conveying pipeline.

[0015] Compared with the prior art, the beneficial effects of the utility model are:

[0016] (1) The heat carrier system with hot blast furnace group as the core equipment is adopted, and the self-produced coal gas is used as the heat carrier for pyrolysis, which eliminates the mixing of inert gas and can effectively ensure the quality of pyrolysis coal gas. The content of effective components in the coal gas, especially H2, CO and CH4, is high, and the calorific value of the coal gas reaches 3500-4500kcal / Nm 3 , which is of great significance to the deep processing of coal gas;

[0017] (2) The hot flue gas generated by the hot blast furnace group is used as a heat carrier to dry the pulverized coal, which effectively utilizes the waste heat of the flue gas, reduces the heat consumption of pyrolysis, and thus reduces the energy consumption of the system;

[0018] (3) The dust removal ash is mixed with the tar residue produced by the system and then formed. On the one hand, it realizes the resource utilization of waste, and on the other hand, it reduces the fine dust in the system, which is beneficial to improving the quality of tar;

[0019] (4) The internal heating rotary furnace with hot gas carrier is used for pulverized coal pyrolysis, which has a large system processing capacity, improves pyrolysis efficiency, and reduces pyrolysis energy consumption;

[0020] (5) The coke particle moving bed is used to separate high-temperature oil gas and dust, which does not consume extra heat or use extra filter materials, and can achieve efficient separation of oil gas and dust to ensure the quality of tar;

[0021] (6) The waste heat recovery system uses a partition heat exchanger to recover the sensible heat of red coke, reducing system energy consumption;

[0022] (7) The semi-coke is cooled by a cooling rotary kiln using flue gas as a cooling carrier, which effectively realizes the cooling and passivation of the hot semi-coke and ensures the safety of the subsequent material handling system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a low-grade pulverized coal pyrolysis system of an internal heating rotary furnace described in the utility model.

[0024] In the figure: 101. Air blower 102. Hot air furnace group 103. Flue gas heat exchanger 201. Raw coal conveyor 202. Raw coal bin 203. Raw coal weighing machine 204. Raw coal feeder 205. Drying rotary kiln 206. Flue gas dust removal device 207 Coal powder forming device 301. Dry coal conveyor 302. Dry coal buffer bin 303. Dry coal feeder 304. Pyrolysis rotary kiln 305. Coke particle screener 401. Partition wall heat exchanger 402. Steam drum 50 1. Coke powder buffer bin 502. Coke moving bed 503. Semi-coke feeder 504. Cooling rotary kiln 505. Cooling semi-coke conveyor 506. Passivation air intake fan 507. Flue gas condenser 508. Coke discharge and dust removal device 509. Accident quenching trolley 510. Accident coke conveyor 511. Accident coke bin 601. Direct cooling tower 602. Indirect cooling tower 603. Electric tar collector 604. Gas fan 605. Tar ammonia separator 7. Semi-coke processing system DETAILED DESCRIPTION

[0025] The specific implementation of the utility model is further described below in conjunction with the accompanying drawings:

[0026] like Figure 1 As shown, the internal heating rotary furnace low-grade pulverized coal pyrolysis system described in the utility model includes: a heat carrier system, a pulverized coal drying system, a pulverized coal pyrolysis system, a waste heat recovery system, a semi-coke cooling system and an oil and gas recovery system, and the specific components are as follows:

[0027] (1) Heat carrier system, consisting of air blower 101, hot air furnace group 102, flue gas heat exchanger 103, and corresponding pipelines, valves and control systems;

[0028] (2) Pulverized coal drying system, which consists of a raw coal conveyor 201, a raw coal bin 202, a raw coal weighing machine 203, a raw coal feeder 204, a drying rotary kiln 205, a flue gas dust removal device 206, a chimney, a pulverized coal molding device 207, and corresponding pipelines, valves and control systems;

[0029] (3) A pulverized coal pyrolysis system, which is composed of a dry coal conveyor 301, a dry coal buffer bin 302, a dry coal feeder 303, a pyrolysis rotary furnace 304, a coke particle sifter 305, and corresponding pipelines, valves, and a control system;

[0030] (4) Waste heat recovery system, consisting of a partition heat exchanger 401, a steam drum 402, and corresponding pipelines, valves, and a control system;

[0031] (5) Semi-coke cooling system, which consists of coke powder buffer bin 501, coke particle moving bed 502, semi-coke feeder 503, cooling rotary kiln 504, cooling semi-coke conveyor 505, passivation air intake fan 506, flue gas condenser 507, coke discharge and dust removal device 508, emergency coke quenching trolley 509, emergency coke conveyor 510, emergency coke bin 511, and corresponding pipelines, valves and control systems;

[0032] (6) Oil and gas recovery system, which consists of a direct cooling tower 601, an indirect cooling tower 602, an electric tar collector 603, a gas blower 604, a tar-ammonia water separator 605, and corresponding pipelines, valves and control systems.

[0033] Preferably, the hot blast furnace group 102 is composed of two or more hot blast furnaces, which generate heat by burning externally supplied coal gas or fuel coal gas to heat the heat carrier coal gas, and can stably output hot flue gas and hot coal gas.

[0034] Preferably, the drying rotary kiln 205 is an internally heated furnace using hot flue gas as a heat carrier. The hot flue gas can directly exchange heat with the raw coal in parallel or countercurrent flow, and the shell wall can be assisted by externally heated steam.

[0035] Preferably, the pyrolysis rotary furnace 304 is an internally heated furnace using hot coal gas as a heat carrier, and the hot coal gas and dry coal are directly exchanged with each other in parallel.

[0036] Preferably, the coke particle screener 305 can be an independent device, or the function of the coke particle screener can be realized by integrating a screen in the pyrolysis rotary furnace.

[0037] Preferably, the partition wall heat exchanger 401 is installed on the outer wall and / or inside of the coke powder buffer bin and the coke particle moving bed to realize partial waste heat recovery of the high-temperature semi-coke.

[0038] Preferably, the cooling rotary kiln 504 is a combined internal and external heating furnace containing a low-concentration oxygen flue gas carrier, the flue gas carrier can directly exchange heat with the hot semi-coke in parallel or countercurrent flow and passivate the semi-coke, and the shell wall is indirectly cooled by circulating water.

[0039] In the low-grade pulverized coal pyrolysis system of an internal heating rotary furnace described in the utility model, the heat carrier system provides hot flue gas and hot coal gas for the pulverized coal drying system and the pulverized coal pyrolysis system respectively; the pulverized coal drying system dries the pulverized coal and separates the coal dust therein and returns it to the furnace directly or after forming; the pulverized coal pyrolysis system pyrolyzes the dry coal, and the generated high-temperature semi-coke is graded after being screened by a coke particle screener for waste heat recovery and steam generation; the semi-coke cooling system further cools the coke powder and coke particles after waste heat recovery and sends them to the outside; the hot waste coal gas is dedusted by a coke particle moving bed and then enters the oil and gas recovery system to obtain coal tar and clean coal gas; a part of the clean coal gas is returned to the furnace and sent to the heat carrier system, and the remaining part is sent to the outside.

[0040] Preferably, the hot air furnace group 102 of the heat carrier system generates heat by burning external coal gas or fuel gas at 30-50°C to heat the heat carrier gas, thereby providing both 180-350°C hot flue gas for the pulverized coal drying system and 600-950°C hot coal gas for the pulverized coal pyrolysis system.

[0041] Preferably, in the pulverized coal drying system, the raw coal and the hot flue gas from the heat carrier system are directly exchanged in parallel or countercurrent in the drying rotary kiln 205, and the raw coal is heated to 110-250°C, and the water content is reduced to below 8wt% before being sent to the pulverized coal pyrolysis system; at the same time, the flue gas is cooled and then enters the flue gas dust removal device 206 to achieve smoke and dust separation, and the flue gas is discharged after being qualified. The dust ash with a particle size of 0-0.2mm is directly sent to the pulverized coal pyrolysis system, or is sent to the coal powder molding device 207, and is mixed with the tar residue or other types of molding agents from the oil and gas recovery system and then sent to the pulverized coal pyrolysis system.

[0042] Preferably, in the pulverized coal pyrolysis system, dry coal and hot coal gas from the heat carrier system directly exchange heat in parallel in the pyrolysis rotary furnace 304 to produce a pyrolysis reaction and are heated to 500-850°C to generate high-temperature semi-coke and oil and gas; the high-temperature semi-coke is separated into two levels by the coke particle screener 305, and coke powder of 0-5 mm enters the coke powder buffer bin 501, and coke particles of 5-30 mm (excluding 5 mm) enter the coke particle moving bed 502 together with the oil and gas; the particle size composition of coke powder and coke particles can be adjusted by adjusting the sieve hole size of the coke particle screener 305.

[0043] Preferably, the upper part of the coke moving bed 502 realizes the separation of high-temperature oil, gas and dust through the slowly downward moving coke bed layer; the lower part cools the coke at 500-850°C to 250-350°C through the partition heat exchanger 401; a gas collecting array umbrella is arranged in the middle part of the coke moving bed 502, and the high-temperature oil and gas enter the subsequent direct cooling tower 601 through the gas collecting array umbrella under the negative pressure of the pipeline connected to the oil and gas recovery system, and the oil, gas and ammonia water are separated through direct cooling, indirect cooling, electrostatic precipitator tar and tar ammonia water separation, and part of the coal gas is returned to the furnace for use in the hot air furnace group 102, and the rest of the coal gas is sent out.

[0044] Preferably, the coke powder buffer bin 501 uses a coke powder layer to seal the high-temperature oil and gas, and cools the coke powder at 500-850°C to 100-200°C through the partition heat exchanger 401 during the coke powder's descent; the medium and low pressure steam generated by the partition heat exchanger 401 is transported externally.

[0045] Preferably, coke powder of 0 to 5 mm and coke particles of 5 to 30 mm (not including 5 mm) are mixed together into the cooling rotary kiln 504 after waste heat recovery, and the flue gas containing low concentration of oxygen at 80 to 120°C taken out from the flue gas duct downstream of the flue gas dust removal device 206 is heat exchanged in parallel or countercurrent with coke particles at 250 to 350°C and coke powder at 100 to 200°C, and the flue gas and mixed semi-coke are indirectly cooled to 40 to 80°C by circulating water introduced into the outer wall of the cooling rotary kiln 504, and the semi-coke is discharged to the semi-coke treatment system 7, and the dust ash is returned to the coal powder forming device 207.

[0046] Preferably, if the semi-coke cooling system fails, coke powder of 0 to 5 mm and coke particles of 5 to 30 mm (excluding 5 mm) can be discharged from the bypass to the accident quenching trolley 509 and the accident coke bin 511 for treatment after being recovered by waste heat.

[0047] Preferably, the low-rank pulverized coal of the utility model includes lignite, long flame coal, weakly sticky coal and non-sticky coal, and has a particle size of 0 to 30 mm.

[0048] In order to more intuitively embody the utility model, the implementation method of the utility model is further described in combination with the examples. The following examples are only preferred specific implementation methods of the utility model, but the protection scope of the utility model is not limited thereto. Any technical solution that can be obviously obtained by a person skilled in the art within the technical scope disclosed in the utility model, including simple changes or equivalent replacements, is within the protection scope of the utility model.

[0049] [Example]

[0050] like Figure 1 As shown, in this embodiment, the internal heating rotary furnace low-grade pulverized coal pyrolysis system includes: a heat carrier system, a pulverized coal drying system, a pulverized coal pyrolysis system, a waste heat recovery system, a semi-coke cooling system and an oil and gas recovery system. The process is as follows:

[0051] The hot air furnace group 102 of the heat carrier system generates heat by burning 35-45°C fuel gas to heat the heat carrier gas, stably providing 280-320°C hot flue gas for the pulverized coal drying system, and at the same time providing 700-800°C hot gas for the pulverized coal pyrolysis system.

[0052] The low-grade pulverized coal (with a particle size of 0-30 mm) is transported to the raw coal bunker 202 by the raw coal conveyor 201, and fed to the drying rotary kiln 205 through the raw coal weighing machine 203 and the raw coal feeder 204, and enters the drying rotary kiln 205 in parallel with the hot flue gas of 280-320°C from the heat carrier system. The hot flue gas exchanges heat with the raw coal, and the raw coal is heated to 160-220°C, and the water content is reduced to below 8wt%. After that, it is sent to the dry coal buffer bunker 302 of the pulverized coal pyrolysis system through the dry coal conveyor 301; at the same time, the flue gas is cooled and then enters the flue gas dust removal device 206 to separate the smoke and dust, and the smoke is discharged after being treated as qualified. The dust removal ash with a particle size of 0-0.2 mm is sent to the coal powder molding device 207, and is mixed with the tar residue of the oil and gas recovery system and then sent to the dry coal buffer bunker 302.

[0053] In the pulverized coal pyrolysis system, the dry coal feeder 303 feeds the dry coal into the pyrolysis rotary furnace 304, and directly exchanges heat with the hot coal gas of 700-800°C from the heat carrier system in parallel to produce a pyrolysis reaction and is heated to 500-650°C to generate high-temperature semi-coke and oil and gas; the high-temperature semi-coke is separated into two levels by the coke particle screener 305, and the coke powder of 0-5 mm enters the coke powder buffer bin 501, and the coke particles of 5-30 mm (excluding 5 mm) enter the coke particle moving bed 502 together with the oil and gas; the particle size composition of the coke powder and coke particles is adjusted by adjusting the sieve hole size of the coke particle screener 305.

[0054] The upper part of the coke moving bed 502 realizes the separation of high-temperature oil, gas and dust through the slowly downward moving coke bed layer; the lower part cools the coke at 500-650°C to 280-320°C through the partition heat exchanger 401; a gas collecting array umbrella is arranged in the middle part of the coke moving bed 502, and the high-temperature oil and gas enter the subsequent direct cooling tower 601 through the gas collecting array umbrella under the negative pressure of the pipeline connected to the oil and gas recovery system, and the oil, gas and ammonia water are separated through direct cooling, indirect cooling, electrostatic precipitator tar and tar ammonia water separation. Part of the gas is returned to the furnace to supply the hot air furnace group 102 as fuel gas and heat carrier gas, and the rest of the gas is sent out.

[0055] The coke powder buffer bin 501 uses the coke powder layer to seal the high-temperature oil and gas, and cools the coke powder at 500-650°C to 100-160°C through the partition heat exchanger 401 during the coke powder's descent; the medium and low pressure steam generated by the partition heat exchanger 401 is sent out.

[0056] After the waste heat is recovered, coke powder of 0-5 mm and coke particles of 5-30 mm (excluding 5 mm) are mixed into the cooling rotary kiln 504 through the semi-coke feeder 503. The flue gas containing low oxygen concentration of 80-120°C taken out from the gas pipeline downstream of the flue gas dust removal device 206 is heat exchanged in parallel with the coke particles of 280-320°C and the coke powder of 100-160°C. The flue gas and the mixed semi-coke are indirectly cooled to 40-60°C by the circulating water introduced into the outer wall of the cooling rotary kiln 504. The semi-coke is discharged to the semi-coke treatment system 7, and the dust ash is returned to the coal powder forming device 207.

[0057] The above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent substitutions or changes within the technical scope disclosed by the present invention according to the technical solution and inventive concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An internal heating rotary furnace low-grade pulverized coal pyrolysis system, characterized in that: It includes a heat carrier system, a pulverized coal drying system, a pulverized coal pyrolysis system, a waste heat recovery system, a semi-coke cooling system and an oil and gas recovery system; the heat carrier system is composed of an air blower, a hot air furnace group and a flue gas heat exchanger connected in sequence; the pulverized coal drying system includes a raw coal conveyor, a raw coal bin, a raw coal weighing machine, a raw coal feeder and a drying rotary furnace connected in sequence, and also includes a flue gas dust removal device, a chimney and a pulverized coal molding device; the drying rotary furnace is an internal heating furnace for hot flue gas heat carriers, and the hot flue gas inlet of the drying rotary furnace is connected to the hot flue gas outlet of the flue gas heat exchanger; the drying rotary furnace is connected to the flue gas dust removal device and the chimney in sequence through a flue gas pipeline, and the flue gas dust removal device is connected to the pulverized coal molding device through a dust ash conveying pipeline The pulverized coal pyrolysis system comprises a dry coal conveyor, a dry coal buffer bin, a dry coal feeder and a pyrolysis rotary furnace which are connected in sequence, and also comprises a coke particle sifter; the flue gas dust removal device is connected to the dry coal conveyor through a dust removal ash pipeline, and the pulverized coal molding device is connected to the dry coal conveyor through a briquette conveying pipeline; the pyrolysis rotary furnace is an internally heated furnace with hot coal gas as a heat carrier, and the hot coal gas inlet of the pyrolysis rotary furnace is connected to the hot blast furnace group through a hot coal gas pipeline; the semi-coke cooling system comprises a coke powder buffer bin, a coke particle moving bed, a semi-coke feeder, a cooling rotary furnace, a cooling semi-coke conveyor, a passivation air intake fan, a flue gas condenser and a coke discharge dust removal device; the discharge port of the pyrolysis rotary furnace is connected to the coke powder buffer bin and the coke particle moving bed through a coke particle sifter The discharge ports of the coke powder buffer bin and the coke particle moving bed are connected to the cooling rotary kiln through the semi-coke feeder, and the discharge port of the cooling rotary kiln is connected to the semi-coke processing system through the cooling semi-coke conveyor; the waste heat recovery system includes a partition wall heat exchanger and a steam drum; the coke powder buffer bin and the coke particle moving bed are both provided with a partition wall heat exchanger; the partition wall heat exchanger is connected to the steam drum through a steam pipe and a hot water pipe, and the steam drum is also connected to an external steam delivery pipe; the discharge port of the cooling rotary kiln is connected to the coke exhaust and dust removal device through a flue gas pipe, and the coke exhaust and dust removal device is connected to the coal powder forming device through a dust removal ash conveying pipe, and is connected to the chimney through an external flue gas pipe; the flue gas pipe downstream of the flue gas dust removal device is also connected to the flue gas inlet of the cooling rotary kiln through a flue gas conveying pipe. The flue gas conveying pipeline is provided with an air inlet, a passivation air intake fan and a flue gas condenser; the oil and gas recovery system comprises a direct cooling tower, an intercooling tower, an electric tar collector and a gas fan which are connected in sequence, and the gas fan is also connected to an external gas pipeline and a fuel gas inlet and a heat carrier gas inlet of a hot blast furnace group; the oil and gas recovery system also comprises a tar ammonia water separator; the coke particle moving bed is connected to the direct cooling tower through a raw gas pipeline; the liquid phase outlets of the direct cooling tower, the intercooling tower and the electric tar collector are all connected to the inlet of the tar ammonia water separator, and the tar ammonia water separator is also connected to the direct cooling tower through a circulating ammonia water pipeline, connected to an external tar pipeline through a tar outlet, and connected to a dust ash conveying pipeline downstream of the coke discharge and dust removal device through a tar residue pipeline.

2. The internal heating rotary furnace low-grade pulverized coal pyrolysis system according to claim 1, characterized in that: The semi-coke cooling system also includes an accident quenching trolley, an accident coke conveyor and an accident coke bin which are connected in sequence; the feed end of the accident quenching trolley is simultaneously connected to the discharge ends of the coke powder buffer bin and the coke particle moving bed; the discharge port of the accident coke bin is connected to the semi-coke processing system through a semi-coke conveying pipeline.

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