Low-rank coal pyrolysis control system and control method based on external heating type rotary furnace

Abstract

The invention relates to a low-rank coal pyrolysis control system and method based on an external heating type rotary furnace. The low-rank coal pyrolysis system is composed of a raw coal drying system and a dried coal pyrolysis system. The low-rank coal pyrolysis control system comprises a central control system, a drying control system and a pyrolysis control system, wherein the drying control system and the pyrolysis control system are respectively connected with the central control system; the drying control system comprises a drying process parameter measuring component and a drying process parameter adjusting component; the pyrolysis control system comprises a pyrolysis process parameter measuring component and a pyrolysis process parameter adjusting component; linkage control of a raw coal drying system and a dried coal pyrolysis system and multi-parameter linkage control of production process parameters (including raw coal flow, raw coal moisture, dried coal moisture, fuel heat value, carrier gas flow, fuel flow, combustion-supporting air flow, discharged flue gas flow and the like) are realized through a low-rank coal pyrolysis control system; therefore, the accurate control of the low-rank coal drying and pyrolysis process is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of low-rank coal pyrolysis, and in particular to a low-rank coal pyrolysis control system and a control method based on an externally heated rotary kiln. Background Art

[0002] In the field of low-rank coal pyrolysis and utilization technology, the externally heated rotary kiln is one of the mainstream equipment. The main feature of this equipment is that the external heat source provides heat indirectly, causing the low-rank coal to undergo pyrolysis reaction in the rotary kiln, thereby producing products such as tar, semi-coke and coal gas. It has the advantages of strong raw material adaptability, high-quality coal gas products, simple process and easy operation, and has broad application prospects in industries such as coal chemical industry.

[0003] Low-rank coal typically has a high water content and requires drying before pyrolysis. Therefore, existing pyrolysis processes based on externally heated rotary kilns typically follow a sequence of drying, pyrolysis, and cooling or waste heat recovery. Drying and pyrolysis are the most critical steps, and controlling the operating parameters of the drying and pyrolysis furnaces can effectively control the quality and yield of the final product.

[0004] Currently, the low-rank coal pyrolysis production process using externally heated rotary furnaces relies primarily on manual judgment and operation, with limited measurement points and control parameters, and a low degree of automation, making it impossible to achieve full process automatic control. This not only increases operator workload but also easily leads to operational errors, impacting product yield and quality. Furthermore, different types of raw coal vary significantly in their chemical composition and moisture content, and existing control methods often rely on historically empirically determined parameters for specific coal types. This makes it difficult to quickly adjust the appropriate operating parameters for different types of raw coal, leading to increased production costs and reduced product quality. This also increases the complexity and difficulty of operations for production personnel.

[0005] Chinese invention patent publication number CN109135778B discloses a "reaction control system and method for an externally heated rotary furnace retorting device." Applicable to externally heated rotary furnaces with an outer jacket and inner tubes, the system automatically controls the retorting system temperature through temperature and flow detection devices, control valves, and dampers installed in the hot air system. However, the system only addresses temperature control in the pyrolysis section, not the drying section, and fails to address the coordinated control of multiple parameters, such as raw coal flow rate, raw coal moisture content, dried coal moisture content, and fuel calorific value.

[0006] Chinese invention patent CN109340809B discloses a "control system and method for the preparation and drying of high-volatile pulverized coal." The method achieves pulverized coal drying by controlling parameters such as relative humidity, oxygen content, and drying load. However, the method only addresses the automatic adjustment of gas flow and air distribution in the rotary kiln, and does not address the coordinated control of the drying and pyrolysis processes. Furthermore, the method does not mention the coordinated control of multiple parameters such as raw coal flow, raw coal moisture, and dried coal moisture.

[0007] A U.S. patent application, publication number US20190292466A1, discloses a "Control Method for Pyrolysis Process of Low-Rank Coal," which achieves real-time control of the production process by analyzing the composition of solid, gas, and liquid phases during the pyrolysis of low-rank coal. However, this control method primarily relies on analyzing the composition of the pyrolysis products, does not involve control of the drying system, and does not mention the coordinated control of multiple parameters such as raw coal flow rate, raw coal moisture, dried coal moisture, and fuel calorific value. Summary of the Invention

[0008] The present invention provides a low-rank coal pyrolysis control system and control method based on an externally heated rotary kiln. Through the low-rank coal pyrolysis control system, the linkage control of the raw coal drying system and the dried coal pyrolysis system is realized, as well as the multi-parameter linkage control of the production process parameters (including raw coal flow, raw coal moisture, dried coal moisture, fuel calorific value, carrier gas flow, fuel flow, combustion-supporting air flow, external exhaust gas flow, etc.), thereby realizing precise control of the low-rank coal drying and pyrolysis process.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A low-rank coal pyrolysis control system based on an externally heated rotary kiln, the low-rank coal pyrolysis system consisting of a raw coal drying system and a dried coal pyrolysis system; the low-rank coal pyrolysis control system includes a central control system and a drying control system and a pyrolysis control system respectively connected to the central control system;

[0011] The raw coal drying system includes an externally heated rotary drying furnace, and a raw coal supply unit, a carrier gas supply unit, a steam supply unit, a drying and dust removal unit, and a nitrogen supply unit respectively connected to the rotary drying furnace; the drying control system includes a drying process parameter measurement component and a drying process parameter adjustment component; the drying process parameter measurement component includes a raw coal online monitoring device, a carrier gas online monitoring device, a steam online monitoring device, an exhaust gas online monitoring device, and a drying coal temperature detection device; the drying process parameter adjustment component includes a driving device of the rotary drying furnace, a carrier gas flow adjustment device provided in the carrier gas supply unit, a steam flow adjustment device provided in the steam supply unit, a dust collector and an exhaust gas induced draft fan provided in the drying and dust removal unit, and a nitrogen shut-off valve provided in the nitrogen supply unit;

[0012] The drying coal pyrolysis system includes an externally heated rotary pyrolysis furnace, and a drying coal supply unit, a hot air heating unit, a raw gas treatment unit and a semi-coke conveying device respectively connected to the rotary pyrolysis furnace; the pyrolysis control system includes a pyrolysis process parameter measurement component and a pyrolysis process parameter adjustment component; the pyrolysis process parameter measurement component includes a drying coal online monitoring device, a pyrolysis furnace temperature monitoring device, a hot air furnace control system, a raw gas online monitoring device and a semi-coke online monitoring device; the pyrolysis process parameter adjustment component includes a driving device of the rotary pyrolysis furnace, a circulating fan, a smoke exhaust fan, a combustion-supporting air volume adjustment device and a fuel volume adjustment device arranged in the hot air heating unit, and a gas induced draft fan and a raw gas flow adjustment device arranged in the raw gas treatment unit.

[0013] The raw coal supply unit includes a raw coal conveying device, a raw coal buffer bin and a metering and conveying device connected in sequence, and the discharge port of the metering and conveying device is connected to the feed port of the rotary drying furnace; a drying coal thermometer is provided at the discharge end of the rotary drying furnace; the raw coal online monitoring device includes a buffer bin level meter 1, a raw coal moisture meter, and a raw coal flow meter provided on the metering and conveying device; the signal output ends of the buffer bin level meter 1, the raw coal moisture meter and the raw coal flow meter, and the control end of the metering and conveying device are respectively connected to the central controller; the control end of the driving device of the rotary drying furnace and the signal output end of the drying coal thermometer are respectively connected to the central controller.

[0014] The carrier gas supply unit includes a carrier gas pipeline and a carrier gas flow regulating device arranged on the carrier gas pipeline, the carrier gas pipeline is connected to the carrier gas inlet of the rotary drying furnace; the carrier gas flow regulating device is a carrier gas flow regulating valve; the carrier gas online monitoring device includes a carrier gas flow meter, a carrier gas pressure gauge and a carrier gas thermometer arranged on the carrier gas pipeline, the signal output ends of the carrier gas flow meter, the carrier gas pressure gauge and the carrier gas thermometer, and the carrier gas flow regulating valve are respectively connected to the central controller.

[0015] The steam heating unit consists of a steam pipe and a steam flow regulating device arranged on the steam pipe, and a condensed water pipe. The steam flow regulating device is a steam flow regulating valve; the steam pipe is connected to the steam inlet of the rotary drying furnace, and the condensed water pipe is connected to the condensed water outlet of the rotary drying furnace; the steam online monitoring device includes a steam thermometer, a steam pressure gauge and a steam flow meter arranged on the steam pipe; the signal output ends of the steam thermometer, steam pressure gauge and steam flow meter, and the control end of the steam flow regulating valve are respectively connected to the central controller.

[0016] The drying and dust removal unit includes an exhaust gas pipeline and a dust collector and an exhaust gas induced draft fan arranged on the exhaust gas pipeline; the exhaust gas online monitoring device includes an exhaust gas thermometer and an oxygen concentration meter arranged on the exhaust gas pipeline; the nitrogen supply unit includes a nitrogen pipeline and a nitrogen shut-off valve arranged on the nitrogen pipeline; the signal output ends of the exhaust gas thermometer and the oxygen concentration meter, as well as the control ends of the dust collector, the exhaust gas induced draft fan and the nitrogen shut-off valve are respectively connected to the central controller.

[0017] The dry coal supply unit includes a dry coal transfer device, a dry coal buffer bin and a dry coal conveying device connected in sequence, the discharge port of the dry coal conveying device is connected to the feed port of the rotary pyrolysis furnace; the discharge port of the rotary pyrolysis furnace is connected to the semi-coke conveying device through a semi-coke conveying pipe; the dry coal online monitoring device includes a buffer bin level meter 2 and a dry coal moisture meter provided on the dry coal buffer bin, and the signal output ends of the buffer bin level meter 2 and the dry coal moisture meter are respectively connected to the central controller; the semi-coke online monitoring device includes a semi-coke thermometer and a discharge pipe level meter provided on the semi-coke conveying pipe, and the signal output ends of the semi-coke thermometer and the discharge pipe level meter are respectively connected to the central controller.

[0018] The hot air heating unit includes a hot air furnace, a fuel pipeline, a combustion-supporting air pipeline and a flue gas pipeline connected to the hot air furnace, a smoke exhaust fan arranged on the flue gas pipeline, and a circulation fan; the hot air outlet of the hot air furnace is connected to the hot air inlet wind box of the rotary pyrolysis furnace through a high-temperature hot air pipeline, the hot air outlet wind box of the rotary pyrolysis furnace is connected to the flue gas pipeline through a low-temperature hot air pipeline, and a circulation fan is arranged on the low-temperature hot air pipeline; the hot air inlet wind box is provided with a hot air inlet thermometer, and the outlet wind box is provided with a hot air outlet thermometer; the signal output ends of the hot air inlet thermometer and the hot air outlet thermometer are connected to a central controller, and the driving device of the rotary pyrolysis furnace and the control end of the circulation fan are respectively connected to the central controller;

[0019] The fuel online monitoring device includes a fuel calorific value meter, a fuel flow meter, a fuel pressure gauge, and a fuel thermometer installed on the fuel pipeline; the fuel quantity regulating device is a fuel flow regulating valve installed on the fuel pipeline; the signal output ends of the fuel calorific value meter, the fuel flow meter, the fuel pressure gauge, and the fuel thermometer are respectively connected to the central controller; the control end of the fuel flow regulating valve is connected to the central controller;

[0020] The combustion air online monitoring device comprises a combustion air flow meter, a combustion air pressure meter and a combustion air temperature meter arranged on the combustion air pipeline; the signal output ends of the combustion air flow meter, the combustion air pressure meter and the combustion air temperature meter, and the control end of the combustion air flow regulating valve are respectively connected to the central controller.

[0021] The flue gas online monitoring device comprises a flue gas flow meter, a flue gas pressure meter and a flue gas temperature meter arranged on the flue gas pipeline; the signal output ends of the flue gas flow meter, the flue gas pressure meter and the flue gas temperature meter, and the control end of the exhaust fan are respectively connected to the central controller.

[0022] The raw coal gas treatment unit comprises a raw coal gas pipeline, a raw coal gas flow regulating device arranged on the raw coal gas pipeline and a coal gas induced draft fan, and the raw coal gas flow regulating device is a raw coal gas flow regulating valve; the raw coal gas online monitoring device comprises a raw coal gas pressure meter and a raw coal gas temperature meter arranged on the raw coal gas pipeline; the signal output ends of the raw coal gas pressure meter and the raw coal gas temperature meter, and the control ends of the raw coal gas flow regulating valve and the coal gas induced draft fan are respectively connected to the central controller.

[0023] A low-rank coal pyrolysis control method, comprising the following processes:

[0024] 1) Raw coal drying control process: raw coal is sent into a rotary drying furnace through a metering conveying device to complete a drying process, a heat source for the rotary drying furnace is saturated water vapor, dried coal after drying and temperature rising is discharged through a discharge box and is sent into a dried coal pyrolysis system through a dried coal transfer device; a specific control process is as follows:

[0025] Raw coal drying process control parameters are input in advance in the central controller, including a raw coal flow set value, a raw coal buffer storage bin level set value, a tail gas pressure set value after drying, a steam pressure set value and a dried coal discharge temperature set value; then the raw coal drying process is automatically controlled through the central controller;

[0026] a. The level of raw coal in the raw coal buffer storage bin is controlled within a set range by adjusting the raw coal conveying device;

[0027] b. The raw coal flow is controlled within a set range by adjusting the metering conveying device;

[0028] c. The carrier gas flow is controlled at a carrier gas flow target value by adjusting the opening degree of the carrier gas flow regulating valve; the carrier gas flow target value is obtained by real-time calculation of the central controller on the basis of feedback values of carrier gas related parameters, and the carrier gas related parameters include the raw coal flow, the raw coal moisture, the dried coal moisture, the carrier gas pressure and the carrier gas temperature;

[0029] d. The tail gas pressure after drying is controlled within a set range by adjusting the tail gas induced draft fan;

[0030] e. Control the steam pressure within the set range by adjusting the opening of the steam flow control valve;

[0031] f. By adjusting the driving device of the rotary drying furnace, the temperature of the dry coal discharged from the discharge box is controlled within the set range;

[0032] 2) Dry coal pyrolysis control process: The dry coal is fed into the rotary pyrolysis furnace through the dry coal buffer and dry coal conveying device to complete the pyrolysis process. The heat source used by the rotary pyrolysis furnace is the high-temperature hot air generated by the hot air furnace. After pyrolysis, high-temperature semi-coke and raw coal gas are obtained. The high-temperature semi-coke and raw coal gas are discharged through corresponding pipelines for subsequent treatment. The specific control process is as follows:

[0033] Input the control parameters of the dry coal pyrolysis process into the central controller in advance, including the dry coal buffer level setting value, the raw gas pressure setting value, the hot air inlet temperature setting value, the semi-coke discharge temperature setting value, and the discharge pipe level setting value, and then automatically control the dry coal pyrolysis process through the central controller;

[0034] a. Ensure that the material level of dry coal in the dry coal buffer bin is within the set range by adjusting the dry coal transfer device;

[0035] b. Ensure that the raw gas pressure is controlled within the set range by adjusting the opening of the gas induced draft fan and the raw gas flow regulating valve;

[0036] c. Ensure that the semi-coke material level in the discharge pipe is controlled within the set range by adjusting the semi-coke conveying device;

[0037] d. Ensure that the semi-coke discharge temperature is controlled within the set range by adjusting the rotary pyrolysis furnace;

[0038] e. By adjusting the opening of the fuel flow control valve, the fuel flow is controlled at the fuel flow target value. The fuel flow target value is calculated in real time by the central controller based on the feedback values ​​of fuel-related parameters. Fuel-related parameters include fuel calorific value, raw coal flow, raw coal moisture, dried coal moisture, fuel pressure and fuel temperature;

[0039] f. By adjusting the opening of the combustion air flow control valve, the combustion air flow is controlled at the combustion air target value. The combustion air target value is calculated in real time by the central controller based on the feedback values ​​of the combustion air related parameters, including the fuel calorific value, fuel flow, combustion air pressure and combustion air temperature;

[0040] g. By adjusting the exhaust fan, the exhaust gas flow rate is controlled at the exhaust gas target value. The exhaust gas target value is calculated in real time by the central controller based on the feedback values ​​of the exhaust gas related parameters. The exhaust gas related parameters include fuel calorific value, fuel flow rate, combustion air flow rate, exhaust gas pressure and exhaust gas temperature;

[0041] h. Control the hot air inlet temperature of the rotary pyrolysis furnace within the target range by adjusting the circulating fan.

[0042] During the raw coal drying control process, the tail gas thermometer 1, tail gas thermometer 2 and oxygen concentration meter are interlocked through the central controller. When the tail gas temperature measured by tail gas thermometer 1 and tail gas thermometer 2 exceeds the limit value, or the oxygen concentration in the tail gas measured by the oxygen concentration meter exceeds the limit value, an automatic alarm is triggered and the nitrogen shut-off valve is automatically opened to protect the system.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1) High degree of automation: The present invention realizes full-process automatic control of the low-rank coal pyrolysis (including drying and pyrolysis) process. Compared with the traditional operation method relying on manual experience, it reduces the labor intensity of the operator and avoids operational errors.

[0045] 2) Strong adaptability to raw materials: Through parametric control, the present invention can quickly adjust relevant production process parameters for raw coal with different chemical components and moisture content, thereby quickly adjusting to the optimal operating conditions, with stronger production adaptability and faster reaction speed.

[0046] 3) More precise production process control: The present invention can detect abnormalities in a timely manner and automatically adjust them by real-time monitoring of process operating parameters; it can also combine the test results of raw coal and finished products to reversely correct and optimize the process parameter setting values.

[0047] 4) Energy saving and environmental protection: The present invention improves thermal efficiency and reduces energy waste through refined regulation, while also avoiding the emission of excess flue gas, which is beneficial to environmental protection.

[0048] 5) Improved product yield and quality stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a structural schematic diagram of the drying system of the present invention.

[0050] Figure 2 It is a structural schematic diagram of the pyrolysis system of the present invention.

[0051] Figure 3 This is a schematic diagram of a low-rank coal pyrolysis control system based on an externally heated rotary furnace described in the present invention.

[0052] In the figure: 11. Raw coal supply unit 11-1. Raw coal conveying device 11-2. Raw coal buffer 11-3. Metering and conveying device 12. Rotary drying furnace 13. Carrier gas supply unit 14. Steam supply unit 15. Drying and dust removal unit 15-1. Dust collector 15-2. Exhaust draft fan

[0053] 21. Dry Coal Supply Unit 21-1. Dry Coal Transfer Device 21-2. Dry Coal Buffer 21-3. Dry Coal Conveying Device 22. Rotary Pyrolysis Furnace 23. Hot Air Heating Unit 23-1. Circulating Fan 23-2. Hot Air Furnace 23-3. Smoke Exhaust Fan 24. Raw Gas Treatment Unit 24-1. Gas Induced Draft Fan 25. Semi-coke Conveying Device

[0054] L101. Buffer Bin Level Meter 1. L201. Buffer Bin Level Meter 2. L202. Discharge Pipeline Level Meter. M101. Raw Coal Moisture Meter. M201. Dry Coal Moisture Meter. W101. Raw Coal Flow Meter. T101. Dry Coal Thermometer. T102. Exhaust Gas Thermometer 1. T103. Exhaust Gas Thermometer 2. T104. Steam Thermometer. T105. Carrier Gas Thermometer. T201. Hot Air Inlet Thermometer. T202. Hot Air Outlet Thermometer. T203. Semi-coke Thermometer. T204. Raw Coal Gas Thermometer. T205. Fuel thermometer T206. Combustion air thermometer T207. Flue gas thermometer P101. Exhaust gas pressure gauge P102. Steam pressure gauge P103. Carrier gas pressure gauge P201. Raw gas pressure gauge P202. Fuel pressure gauge P203. Combustion air pressure gauge P204. Flue gas pressure gauge A101. Oxygen concentration meter Q101. Steam flowmeter Q102. Carrier gas flowmeter Q201. Fuel flowmeter Q202. Combustion air flowmeter Q203. Flue gas flowmeter C201. Fuel calorific value meter DETAILED DESCRIPTION

[0055] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0056] like Figure 1-Figure 3 As shown, the present invention discloses a low-rank coal pyrolysis control system based on an externally heated rotary kiln. The low-rank coal pyrolysis system is composed of a raw coal drying system and a dried coal pyrolysis system. The low-rank coal pyrolysis control system includes a central control system and a drying control system and a pyrolysis control system respectively connected to the central control system.

[0057] The raw coal drying system includes an externally heated rotary drying furnace 12, and a raw coal supply unit 11, a carrier gas supply unit 13, a steam supply unit 14, a drying and dust removal unit 15, and a nitrogen supply unit respectively connected to the rotary drying furnace 12; the drying control system includes a drying process parameter measurement component and a drying process parameter adjustment component; the drying process parameter measurement component includes a raw coal online monitoring device, a carrier gas online monitoring device, a steam online monitoring device, an exhaust gas online monitoring device, and a drying coal temperature detection device; the drying process parameter adjustment component includes a driving device of the rotary drying furnace 12, a carrier gas flow adjustment device provided in the carrier gas supply unit 13, a steam flow adjustment device provided in the steam supply unit 14, a dust collector 15-1 and an exhaust gas induced draft fan 15-2 provided in the drying and dust removal unit 15, and a nitrogen shut-off valve provided in the nitrogen supply unit;

[0058] The drying coal pyrolysis system includes an externally heated rotary pyrolysis furnace 22, and a drying coal supply unit 21, a hot air heating unit 23, a raw gas treatment unit 24 and a semi-coke conveying device 25 respectively connected to the rotary pyrolysis furnace 22; the pyrolysis control system includes a pyrolysis process parameter measurement component and a pyrolysis process parameter adjustment component; the pyrolysis process parameter measurement component includes a drying coal online monitoring device, a pyrolysis furnace temperature monitoring device, a hot air furnace control system, a raw gas online monitoring device and a semi-coke online monitoring device; the pyrolysis process parameter adjustment component includes a driving device of the rotary pyrolysis furnace 22, a circulating fan 23-1, a smoke exhaust fan 23-3, a combustion-supporting air volume adjustment device and a fuel volume adjustment device arranged in the hot air heating unit 23, and a gas induced draft fan 24-1 and a raw gas flow adjustment device arranged in the raw gas treatment unit 24.

[0059] The raw coal supply unit 11 includes a raw coal conveying device 11-1, a raw coal buffer bin 11-2 and a metering and conveying device 11-3 connected in sequence, and the discharge port of the metering and conveying device 11-3 is connected to the feed port of the rotary drying furnace 12; the discharge end of the rotary drying furnace 12 is provided with a drying coal thermometer T101; the raw coal online monitoring device includes a buffer bin level meter L101, a raw coal moisture meter M101, and a raw coal flow meter W101 provided on the raw coal buffer bin 11-2; the signal output ends of the buffer bin level meter L101, the raw coal moisture meter M101 and the raw coal flow meter W101, and the control end of the metering and conveying device 11-3 are respectively connected to the central controller; the control end of the driving device of the rotary drying furnace 12 and the signal output end of the drying coal thermometer T101 are respectively connected to the central controller.

[0060] The carrier gas supply unit 13 includes a carrier gas pipeline and a carrier gas flow regulating device provided on the carrier gas pipeline, the carrier gas pipeline is connected to the carrier gas inlet of the rotary drying furnace 12; the carrier gas flow regulating device is a carrier gas flow regulating valve; the carrier gas online monitoring device includes a carrier gas flowmeter Q102, a carrier gas pressure gauge P103 and a carrier gas thermometer T105 provided on the carrier gas pipeline, the signal output ends of the carrier gas flowmeter Q102, the carrier gas pressure gauge P103 and the carrier gas thermometer T105, and the carrier gas flow regulating valve are respectively connected to the central controller.

[0061] The steam heating unit 14 is composed of a steam pipe and a steam flow regulating device arranged on the steam pipe, and a condensed water pipe. The steam flow regulating device is a steam flow regulating valve; the steam pipe is connected to the steam inlet of the rotary drying furnace 12, and the condensed water pipe is connected to the condensed water outlet of the rotary drying furnace 12; the steam online monitoring device includes a steam thermometer T104, a steam pressure gauge P102 and a steam flow meter Q101 arranged on the steam pipe; the signal output ends of the steam thermometer T104, the steam pressure gauge P102 and the steam flow meter Q101, and the control end of the steam flow regulating valve are respectively connected to the central controller.

[0062] The drying and dust removal unit 15 includes an exhaust gas pipeline and a dust collector 15-1 and an exhaust draft fan 15-2 arranged on the exhaust gas pipeline; the exhaust gas online monitoring device includes an exhaust gas thermometer T102 and an oxygen concentration meter A101 arranged on the exhaust gas pipeline; the nitrogen supply unit includes a nitrogen pipeline and a nitrogen shut-off valve arranged on the nitrogen pipeline; the signal output ends of the exhaust gas thermometer T102 and the oxygen concentration meter A101, as well as the control ends of the dust collector 15-1, the exhaust draft fan 15-2 and the nitrogen shut-off valve are respectively connected to the central controller.

[0063] The dry coal supply unit 21 includes a dry coal transfer device 21-1, a dry coal buffer bin 21-2 and a dry coal conveying device 21-3 connected in sequence, and the discharge port of the dry coal conveying device 21-3 is connected to the feed port of the rotary pyrolysis furnace 22; the discharge port of the rotary pyrolysis furnace 22 is connected to the semi-coke conveying device 25 through a semi-coke conveying pipeline; the dry coal online monitoring device includes a buffer bin level meter L201 and a dry coal moisture meter M201 arranged on the dry coal buffer bin 21-2, and the signal output ends of the buffer bin level meter L201 and the dry coal moisture meter M201 are respectively connected to the central controller; the semi-coke online monitoring device includes a semi-coke thermometer T203 and a discharge pipe level meter L202 arranged on the semi-coke conveying pipeline, and the signal output ends of the semi-coke thermometer T203 and the discharge pipe level meter L202 are respectively connected to the central controller.

[0064] The hot air heating unit 23 includes a hot air furnace 23-2, a fuel pipeline, a combustion-supporting air pipeline and a flue gas pipeline connected to the hot air furnace 23-2, a smoke exhaust fan 23-3 provided on the flue gas pipeline, and a circulation fan 23-1; the hot air outlet of the hot air furnace 23-2 is connected to the hot air inlet blower of the rotary pyrolysis furnace 22 through a high-temperature hot air pipeline, and the hot air outlet blower of the rotary pyrolysis furnace 22 is connected to the flue gas pipeline through a low-temperature hot air pipeline, and the circulation fan 23-1 is provided on the low-temperature hot air pipeline; the hot air inlet blower is provided with a hot air inlet thermometer T201, and the outlet blower is provided with a hot air outlet thermometer T202; the signal output ends of the hot air inlet thermometer T201 and the hot air outlet thermometer T202 are connected to the central controller, and the drive device of the rotary pyrolysis furnace 22 and the control end of the circulation fan 23-1 are respectively connected to the central controller;

[0065] The fuel online monitoring device includes a fuel calorific value meter C201, a fuel flow meter Q201, a fuel pressure gauge P202, and a fuel temperature meter T205 installed on the fuel pipeline; the fuel quantity regulating device is a fuel flow regulating valve installed on the fuel pipeline; the signal output ends of the fuel calorific value meter C201, the fuel flow meter Q201, the fuel pressure gauge P202, and the fuel temperature meter T205 are respectively connected to the central controller; the control end of the fuel flow regulating valve is connected to the central controller;

[0066] The combustion-supporting air online monitoring device includes a combustion-supporting air flow meter Q202, a combustion-supporting air pressure gauge P203, and a combustion-supporting air temperature gauge T206 provided on the combustion-supporting air duct; the combustion-supporting air volume regulating device is a combustion-supporting air flow regulating valve provided on the combustion-supporting air duct; the signal output ends of the combustion-supporting air flow meter Q202, the combustion-supporting air pressure gauge P203, and the combustion-supporting air temperature gauge T206, as well as the control end of the combustion-supporting air flow regulating valve are respectively connected to the central controller;

[0067] The flue gas online monitoring device includes a flue gas flow meter Q203, a flue gas pressure meter P204 and a flue gas thermometer T207 installed on the flue gas duct; the signal output ends of the flue gas flow meter Q203, the flue gas pressure meter P204 and the flue gas thermometer T207, and the control end of the exhaust fan 23-3 are respectively connected to the central controller.

[0068] The raw gas processing unit 24 includes a raw gas pipeline, a raw gas flow regulating device installed on the raw gas pipeline, and a gas draft fan 24-1. The raw gas flow regulating device is a raw gas flow regulating valve; the raw gas online monitoring device includes a raw gas pressure gauge P201 and a raw gas thermometer T204 installed on the raw gas pipeline; the signal output ends of the raw gas pressure gauge P201 and the raw gas thermometer T204, as well as the control ends of the raw gas flow regulating valve and the gas draft fan 24-1 are respectively connected to the central controller.

[0069] A low-rank coal pyrolysis control method, comprising the following processes:

[0070] 1) Raw coal drying control process: raw coal is sent into a rotary drying furnace 12 through a metering conveying device 11-3 to complete a drying process, the rotary drying furnace 12 adopts saturated steam as a heat source, and the dried and heated coal is discharged from a discharge box and sent into a dried coal pyrolysis system through a dried coal transfer device 21-1; the specific control process is as follows:

[0071] The raw coal drying process control parameters, including a raw coal flow set value, a raw coal buffer bin level set value, a dried tail gas pressure set value, a steam pressure set value and a dried coal discharge temperature set value, are input in advance in a central controller, and then the raw coal drying process is automatically controlled through the central controller;

[0072] a. The raw coal level in the raw coal buffer bin 11-2 is controlled within a set range by adjusting the raw coal conveying device 11-1;

[0073] b. The raw coal flow is controlled within a set range by adjusting the metering conveying device 11-3;

[0074] c. The carrier gas flow is controlled at a carrier gas flow target value by adjusting the opening degree of a carrier gas flow regulating valve; the carrier gas flow target value is obtained by real-time calculation of the central controller based on the feedback values of carrier gas related parameters, including raw coal flow, raw coal moisture, dried coal moisture, carrier gas pressure and carrier gas temperature;

[0075] d. The dried tail gas pressure is controlled within a set range by adjusting a tail gas induced draft fan 15-2;

[0076] e. The steam pressure is controlled within a set range by adjusting the opening degree of a steam flow regulating valve;

[0077] f. The temperature of the dried coal discharged from the discharge box is controlled within a set range by adjusting the driving device of the rotary drying furnace 12;

[0078] 2) Dried coal pyrolysis control process: dried coal is sent into a rotary pyrolysis furnace 22 through a dried coal buffer bin 21-2 and a dried coal conveying device 21-3 to complete a pyrolysis process, the rotary pyrolysis furnace 22 adopts high-temperature hot air generated by a hot air furnace 23-2 as a heat source, and high-temperature semicoke and raw coal gas are obtained after pyrolysis, and the high-temperature semicoke and raw coal gas are discharged through corresponding pipelines for subsequent treatment; the specific control process is as follows:

[0079] The dried coal pyrolysis process control parameters, including a dried coal buffer bin 21-2 level set value, a raw coal gas pressure set value, a hot air inlet temperature set value, a semicoke discharge temperature set value and a discharge pipeline level set value, are input in advance in a central controller, and then the dried coal pyrolysis process is automatically controlled through the central controller;

[0080] a. Ensure that the material level of the dry coal in the dry coal buffer bin 21-2 is within the set range by adjusting the dry coal transfer device 21-1;

[0081] b. Ensure that the raw gas pressure is controlled within the set range by adjusting the opening of the gas induced draft fan 24-1 and the raw gas flow regulating valve;

[0082] c. Ensure that the semi-coke material level in the discharge pipe is controlled within a set range by adjusting the semi-coke conveying device 25;

[0083] d. By adjusting the rotary pyrolysis furnace 22, ensure that the semi-coke discharge temperature is controlled within the set range;

[0084] e. By adjusting the opening of the fuel flow control valve, the fuel flow is controlled at the fuel flow target value. The fuel flow target value is calculated in real time by the central controller based on the feedback values ​​of fuel-related parameters. Fuel-related parameters include fuel calorific value, raw coal flow, raw coal moisture, dried coal moisture, fuel pressure and fuel temperature;

[0085] f. By adjusting the opening of the combustion air flow control valve, the combustion air flow is controlled at the combustion air target value. The combustion air target value is calculated in real time by the central controller based on the feedback values ​​of the combustion air related parameters, including the fuel calorific value, fuel flow, combustion air pressure and combustion air temperature;

[0086] g. By adjusting the exhaust fan 23-3, the exhaust gas flow rate is controlled to the exhaust gas target value. The exhaust gas target value is calculated in real time by the central controller based on the feedback values ​​of the exhaust gas related parameters. The exhaust gas related parameters include fuel calorific value, fuel flow rate, combustion air flow rate, exhaust gas pressure and exhaust gas temperature;

[0087] h. By adjusting the circulating fan 23-1, the hot air inlet temperature of the rotary pyrolysis furnace 22 is controlled within the target range.

[0088] During the raw coal drying control process, the tail gas thermometer T102, tail gas thermometer T103 and oxygen concentration meter A101 are interlocked through the central controller. When the tail gas temperature measured by tail gas thermometer T102 and tail gas thermometer T103 exceeds the limit value, or the oxygen concentration in the tail gas measured by oxygen concentration meter A101 exceeds the limit value, an automatic alarm is triggered and the nitrogen shut-off valve is automatically opened to protect the system.

[0089] The low-rank coal pyrolysis control system of the present invention is used to realize automatic control of the production process of a low-rank coal pyrolysis system based on an externally heated rotary furnace. The low-rank coal pyrolysis system includes a raw coal drying system and a dried coal pyrolysis system.

[0090] like Figure 1 As shown, the raw coal drying system includes an externally heated rotary drying furnace 12, and a raw coal supply unit (composed of a raw coal conveying device 11-1, a raw coal buffer bin 11-2, and a metering and conveying device 11-3) connected to the rotary drying furnace 12, a carrier gas supply unit 13, a steam supply unit 14, a drying and dust removal unit 15, and a nitrogen supply unit. The functions of each component and the corresponding control system are as follows:

[0091] Raw coal buffer bin 11-2: used to store raw coal, equipped with a buffer bin level meter L101 (preferably a level sensor) and a raw coal moisture meter M101 (preferably an online moisture detection sensor) to monitor the raw coal level and measure the moisture content of the raw coal.

[0092] Metering and conveying device 11-3: used to quantitatively convey the raw coal in the raw coal buffer bin 11-2 to the rotary drying furnace 12, equipped with a raw coal flow meter W101 (preferably a flow sensor), which can control the raw coal flow by adjusting the motor frequency.

[0093] Rotary drying furnace 12: used to dry the raw coal before pyrolysis; a discharge box and an exhaust gas pipe are provided at the discharge end of the rotary drying furnace 12. The discharge box is equipped with a drying coal thermometer T101 (preferably a temperature sensor), and an exhaust gas thermometer T102 (preferably a temperature sensor) and an exhaust gas pressure gauge P101 (preferably a pressure sensor) are provided on the exhaust gas pipe close to the rotary drying furnace 12; the rotation speed of the furnace body can be controlled by adjusting the driving device of the rotary drying furnace 12 (such as the frequency of the transmission motor).

[0094] Drying and dust removal unit 15: connected to the rotary drying furnace 12 through the exhaust gas pipe, used to discharge and purify the exhaust gas generated when the raw coal is dried; an exhaust gas thermometer T103 (preferably a temperature sensor) and an oxygen concentration meter A101 (preferably an oxygen concentration sensor) are provided on the exhaust gas pipe downstream of the dust collector 15-1; by adjusting the motor frequency of the exhaust draft fan 15-2, the exhaust gas flow and pressure can be controlled.

[0095] Steam heating unit 14: used to provide steam to the rotary drying furnace 12. The steam pipeline is provided with a steam thermometer T104 (preferably a temperature sensor), a steam pressure gauge P102 (preferably a pressure sensor), a steam flow meter Q101 (preferably a flow sensor) and a steam flow regulating valve. By adjusting the opening of the steam flow regulating valve, the flow, pressure and temperature of the steam entering the rotary drying furnace 12 can be controlled.

[0096] Carrier gas supply unit 13: used to provide carrier gas to the rotary drying furnace 12. The carrier gas pipeline is provided with a carrier gas thermometer T105 (preferably a temperature sensor), a carrier gas pressure gauge P103 (preferably a pressure sensor), a carrier gas flow meter Q102 (preferably a flow sensor) and a carrier gas flow regulating valve. By adjusting the opening of the carrier gas flow regulating valve, the flow, pressure and temperature of the carrier gas entering the rotary drying furnace 12 can be controlled.

[0097] Nitrogen supply unit: used to fill nitrogen into the rotary drying furnace 12 in an accident state, and a nitrogen shut-off valve is provided on the nitrogen pipeline.

[0098] like Figure 2 As shown, the dry coal pyrolysis system includes an externally heated rotary pyrolysis furnace 22, a dry coal supply unit 21, a hot air heating unit 23, a raw gas treatment unit 24, and a semi-coke conveying device 25, each connected to the rotary pyrolysis furnace 22. The functions of each component and the corresponding control system are as follows:

[0099] Dry coal buffer bin 21-2: used to store dry coal, equipped with a buffer bin material level meter 2110 (preferably a material level sensor) and a dry coal moisture meter M201 (preferably an online moisture detection sensor).

[0100] Rotary pyrolysis furnace 22: Used to achieve pyrolysis of dried coal; rotary pyrolysis furnace 22 is equipped with a hot air inlet and outlet bellows, and the discharge end of rotary pyrolysis furnace 22 is equipped with a discharge pipe and a raw gas pipe. The hot air inlet bellows is equipped with a hot air inlet thermometer T201 (preferably a temperature sensor), and the outlet bellows is equipped with a hot air outlet thermometer T202 (preferably a temperature sensor); the discharge pipe is equipped with a semi-coke thermometer T203 (preferably a temperature sensor) and a discharge pipe level gauge T202 (preferably a level sensor); the raw gas pipe is equipped with a raw gas thermometer T204 (preferably a temperature sensor) and a raw gas pressure gauge T201 (preferably a pressure sensor); the furnace speed can be controlled by adjusting the drive device of rotary pyrolysis furnace 22 (such as the frequency of the transmission motor).

[0101] The raw gas processing unit 24 is connected to the rotary pyrolysis furnace 22 through a raw gas pipeline and is used to discharge the raw gas generated during the pyrolysis of the dry coal. The raw gas pipeline is equipped with a gas induced draft fan 24-1 and a raw gas flow regulating valve; the flow and pressure of the raw gas can be controlled by adjusting the motor frequency of the gas induced draft fan 24-1.

[0102] Hot air heating unit 23: used to provide hot air to the rotary drying furnace 22; including a hot air furnace 23-2, a circulating fan 23-1, a smoke exhaust fan 23-3, a high-temperature hot air duct, a low-temperature hot air duct, a fuel pipeline, a combustion-supporting air duct, a flue gas duct, etc. The high-temperature hot air duct is connected to the hot air inlet bellows of the rotary pyrolysis furnace 22, and the low-temperature hot air duct is connected to the hot air outlet bellows of the rotary pyrolysis furnace 22. The fuel pipeline is provided with a fuel thermometer He 05 (preferably a temperature sensor), a fuel pressure gauge C02 (preferably a pressure sensor), a fuel flow meter Jin 01 (preferably a flow sensor), a fuel calorific value meter C201 (preferably a calorific value sensor) and a fuel flow regulating valve. The fuel supply amount can be controlled by adjusting the opening of the fuel flow regulating valve. The combustion air duct is equipped with a combustion air thermometer T206 (preferably a temperature sensor), a combustion air pressure gauge P203 (preferably a pressure sensor), a combustion air flow meter Q202 (preferably a flow sensor), and a combustion air flow control valve. Adjusting the opening of the combustion air flow control valve controls the amount of combustion air supplied. The flue gas duct is equipped with a flue gas thermometer T207 (preferably a temperature sensor), a flue gas pressure gauge P204 (preferably a pressure sensor), and a flue gas flow meter Q203 (preferably a flow sensor). Adjusting the motor frequency of the smoke exhaust fan 23-3 controls the amount of exhaust gas; adjusting the motor frequency of the circulation fan 23-1 controls the amount of circulating air.

[0103] The drying control system and the pyrolysis control system and the online monitoring devices (such as various sensors) in the present invention are connected to the central controller and transmit signals in real time. The devices with adjustment functions (such as the metering and conveying device 11-3, the rotary drying furnace 12, the rotary pyrolysis furnace 22, the tail gas draft fan 15-2, the circulating fan 23-1, the smoke exhaust fan 23-3, the gas draft fan 24-1, etc.), as well as the flow regulating valves and the nitrogen shut-off valve are all connected to the central controller and transmit signals in real time to realize communication, control, interlocking and other functions.

[0104] The core control parameters and control logic of the low-rank coal pyrolysis control method of the present invention are as follows:

[0105] Before the system works, it is necessary to manually set the target values ​​of "raw coal flow", "steam pressure", and "dried coal temperature in the discharge box" of the raw coal drying system, as well as the target values ​​of "raw gas pressure", "hot air inlet bellows temperature", and "semi-coke discharge temperature" of the drying coal pyrolysis system. Combined with the measured values ​​of "raw coal moisture", "dried coal moisture", "fuel calorific value", "fuel flow", "combustion-supporting air flow", and "exhaust gas flow", the automatic adjustment and control of the interlocking of related parameters can be achieved.

[0106] The above parameters for manually setting target values ​​(3 for raw coal drying system and 3 for dried coal pyrolysis system) have the following functions:

[0107] (1) If the current system user needs to adjust the system's processing capacity, he can manually adjust the "raw coal flow" input value;

[0108] (2) If the user of the current system needs to adjust the "moisture content of dried coal", he can manually adjust the input values ​​of "steam pressure" and "temperature of dried coal in discharge box". The higher the values, the lower the moisture content.

[0109] (3) "Raw gas pressure" is one of the basic conditions to ensure the normal operation of the rotary pyrolysis furnace. Its value usually remains unchanged after setting. The user of the current system can manually adjust the value between 0 and 500 Pa as needed;

[0110] (4) If the user of the current system needs to adjust the product quality (including the yield and quality indicators of coal gas, tar and semi-coke, which require manual regular testing and judgment), the "hot air inlet bellows temperature" and "semi-coke discharge temperature" can be manually adjusted. The values ​​of the two directly determine the product quality;

[0111] Production can be carried out after the above manual adjustment input action is completed. During the production process, the low-grade coal pyrolysis control system will automatically adjust. During this process, the nitrogen shut-off valve will be opened through alarm and interlock after exceeding the limit value, which are all basic safety protection operations of the system.

[0112] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A low-rank coal pyrolysis control system based on an externally heated rotary kiln, the low-rank coal pyrolysis system consisting of a raw coal drying system and a dried coal pyrolysis system; characterized in that: The low-rank coal pyrolysis control system includes a central control system and a drying control system and a pyrolysis control system respectively connected to the central control system; The raw coal drying system includes an externally heated rotary drying furnace, and a raw coal supply unit, a carrier gas supply unit, a steam supply unit, a drying and dust removal unit, and a nitrogen supply unit respectively connected to the rotary drying furnace; the drying control system includes a drying process parameter measurement component and a drying process parameter adjustment component; the drying process parameter measurement component includes a raw coal online monitoring device, a carrier gas online monitoring device, a steam online monitoring device, an exhaust gas online monitoring device, and a drying coal temperature detection device; the drying process parameter adjustment component includes a driving device of the rotary drying furnace, a carrier gas flow adjustment device provided in the carrier gas supply unit, a steam flow adjustment device provided in the steam supply unit, a dust collector and an exhaust gas induced draft fan provided in the drying and dust removal unit, and a nitrogen shut-off valve provided in the nitrogen supply unit; The drying coal pyrolysis system includes an externally heated rotary pyrolysis furnace, and a drying coal supply unit, a hot air heating unit, a raw gas treatment unit and a semi-coke conveying device respectively connected to the rotary pyrolysis furnace; the pyrolysis control system includes a pyrolysis process parameter measurement component and a pyrolysis process parameter adjustment component; the pyrolysis process parameter measurement component includes a drying coal online monitoring device, a pyrolysis furnace temperature monitoring device, a hot air furnace control system, a raw gas online monitoring device and a semi-coke online monitoring device; the pyrolysis process parameter adjustment component includes a driving device of the rotary pyrolysis furnace, a circulating fan, a smoke exhaust fan, a combustion-supporting air volume adjustment device and a fuel volume adjustment device arranged in the hot air heating unit, and a gas induced draft fan and a raw gas flow adjustment device arranged in the raw gas treatment unit.

2. A low-rank coal pyrolysis control system based on an externally heated rotary kiln according to claim 1, characterized in that: The raw coal supply unit includes a raw coal conveying device, a raw coal buffer bin and a metering and conveying device connected in sequence, and the discharge port of the metering and conveying device is connected to the feed port of the rotary drying furnace; a drying coal thermometer is provided at the discharge end of the rotary drying furnace; the raw coal online monitoring device includes a buffer bin level meter 1, a raw coal moisture meter, and a raw coal flow meter provided on the metering and conveying device; the signal output ends of the buffer bin level meter 1, the raw coal moisture meter and the raw coal flow meter, and the control end of the metering and conveying device are respectively connected to the central controller; the control end of the driving device of the rotary drying furnace and the signal output end of the drying coal thermometer are respectively connected to the central controller.

3. The low-rank coal pyrolysis control system based on an externally heated rotary kiln according to claim 1, characterized in that: The carrier gas supply unit includes a carrier gas pipeline and a carrier gas flow regulating device arranged on the carrier gas pipeline, the carrier gas pipeline is connected to the carrier gas inlet of the rotary drying furnace; the carrier gas flow regulating device is a carrier gas flow regulating valve; the carrier gas online monitoring device includes a carrier gas flow meter, a carrier gas pressure gauge and a carrier gas thermometer arranged on the carrier gas pipeline, the signal output ends of the carrier gas flow meter, the carrier gas pressure gauge and the carrier gas thermometer, and the carrier gas flow regulating valve are respectively connected to the central controller.

4. The low-rank coal pyrolysis control system based on an externally heated rotary kiln according to claim 1, characterized in that: The steam heating unit consists of a steam pipe and a steam flow regulating device arranged on the steam pipe, and a condensed water pipe. The steam flow regulating device is a steam flow regulating valve; the steam pipe is connected to the steam inlet of the rotary drying furnace, and the condensed water pipe is connected to the condensed water outlet of the rotary drying furnace; the steam online monitoring device includes a steam thermometer, a steam pressure gauge and a steam flow meter arranged on the steam pipe; the signal output ends of the steam thermometer, steam pressure gauge and steam flow meter, and the control end of the steam flow regulating valve are respectively connected to the central controller.

5. The low-rank coal pyrolysis control system based on an externally heated rotary kiln according to claim 1, characterized in that: The drying and dust removal unit includes an exhaust gas pipeline and a dust collector and an exhaust gas induced draft fan arranged on the exhaust gas pipeline; the exhaust gas online monitoring device includes an exhaust gas thermometer and an oxygen concentration meter arranged on the exhaust gas pipeline; the nitrogen supply unit includes a nitrogen pipeline and a nitrogen shut-off valve arranged on the nitrogen pipeline; the signal output ends of the exhaust gas thermometer and the oxygen concentration meter, as well as the control ends of the dust collector, the exhaust gas induced draft fan and the nitrogen shut-off valve are respectively connected to the central controller.

6. The low-rank coal pyrolysis control system based on an externally heated rotary kiln according to claim 1, characterized in that: The dry coal supply unit includes a dry coal transfer device, a dry coal buffer bin and a dry coal conveying device connected in sequence, the discharge port of the dry coal conveying device is connected to the feed port of the rotary pyrolysis furnace; the discharge port of the rotary pyrolysis furnace is connected to the semi-coke conveying device through a semi-coke conveying pipe; the dry coal online monitoring device includes a buffer bin level meter 2 and a dry coal moisture meter provided on the dry coal buffer bin, and the signal output ends of the buffer bin level meter 2 and the dry coal moisture meter are respectively connected to the central controller; the semi-coke online monitoring device includes a semi-coke thermometer and a discharge pipe level meter provided on the semi-coke conveying pipe, and the signal output ends of the semi-coke thermometer and the discharge pipe level meter are respectively connected to the central controller.

7. The low-rank coal pyrolysis control system based on an externally heated rotary kiln according to claim 1, characterized in that: The hot air heating unit includes a hot air furnace, a fuel pipeline, a combustion-supporting air pipeline and a flue gas pipeline connected to the hot air furnace, a smoke exhaust fan arranged on the flue gas pipeline, and a circulation fan; the hot air outlet of the hot air furnace is connected to the hot air inlet wind box of the rotary pyrolysis furnace through a high-temperature hot air pipeline, the hot air outlet wind box of the rotary pyrolysis furnace is connected to the flue gas pipeline through a low-temperature hot air pipeline, and a circulation fan is arranged on the low-temperature hot air pipeline; the hot air inlet wind box is provided with a hot air inlet thermometer, and the outlet wind box is provided with a hot air outlet thermometer; the signal output ends of the hot air inlet thermometer and the hot air outlet thermometer are connected to a central controller, and the driving device of the rotary pyrolysis furnace and the control end of the circulation fan are respectively connected to the central controller; The fuel online monitoring device includes a fuel calorific value meter, a fuel flow meter, a fuel pressure gauge, and a fuel thermometer installed on the fuel pipeline; the fuel quantity regulating device is a fuel flow regulating valve installed on the fuel pipeline; the signal output ends of the fuel calorific value meter, the fuel flow meter, the fuel pressure gauge, and the fuel thermometer are respectively connected to the central controller; the control end of the fuel flow regulating valve is connected to the central controller; The combustion-supporting air online monitoring device includes a combustion-supporting air flow meter, a combustion-supporting air pressure gauge, and a combustion-supporting air temperature gauge provided on the combustion-supporting air duct; the combustion-supporting air volume regulating device is a combustion-supporting air flow regulating valve provided on the combustion-supporting air duct; the signal output ends of the combustion-supporting air flow meter, the combustion-supporting air pressure gauge, and the combustion-supporting air temperature gauge, as well as the control end of the combustion-supporting air flow regulating valve are respectively connected to the central controller; The flue gas online monitoring device includes a flue gas flow meter, a flue gas pressure gauge and a flue gas thermometer arranged on the flue gas duct; the signal output ends of the flue gas flow meter, the flue gas pressure gauge and the flue gas thermometer, and the control end of the exhaust fan are respectively connected to the central controller.

8. The low-rank coal pyrolysis control system based on an externally heated rotary kiln according to claim 1, characterized in that: The raw gas processing unit includes a raw gas pipeline, a raw gas flow regulating device and a gas draft fan installed on the raw gas pipeline. The raw gas flow regulating device is a raw gas flow regulating valve; the raw gas online monitoring device includes a raw gas pressure gauge and a raw gas thermometer installed on the raw gas pipeline; the signal output ends of the raw gas pressure gauge and the raw gas thermometer, as well as the control ends of the raw gas flow regulating valve and the gas draft fan are respectively connected to the central controller.

9. A low-rank coal pyrolysis control method, implemented based on the low-rank coal pyrolysis control system based on an externally heated rotary furnace as claimed in any one of claims 1 to 8; characterized in that: The process includes the following: 1) Raw coal drying control process: The raw coal is fed into the rotary drying furnace through a metering conveying device to complete the drying process. The heat source used by the rotary drying furnace is saturated water vapor. The dried coal after drying and heating is discharged from the discharge box and fed into the dry coal pyrolysis system through the dry coal transfer device. The specific control process is as follows: Input the raw coal drying process control parameters into the central controller in advance, including the raw coal flow set value, the raw coal buffer bin material level set value, the tail gas pressure set value after drying, the steam pressure set value and the dried coal discharge temperature set value; then the raw coal drying process is automatically controlled by the central controller; a. Control the raw coal level in the raw coal buffer bin within the set range by adjusting the raw coal conveying device; b. Control the raw coal flow rate within the set range by adjusting the metering and conveying device; c. Control the carrier gas flow rate at the target carrier gas flow rate by adjusting the opening of the carrier gas flow control valve; The carrier gas flow target value is calculated in real time by the central controller based on the feedback values ​​of carrier gas related parameters, including raw coal flow, raw coal moisture, dried coal moisture, carrier gas pressure and carrier gas temperature; d. Control the exhaust gas pressure after drying within the set range by adjusting the exhaust induced draft fan; e. Control the steam pressure within the set range by adjusting the opening of the steam flow control valve; f. By adjusting the driving device of the rotary drying furnace, the temperature of the dry coal discharged from the discharge box is controlled within the set range; 2) Dry coal pyrolysis control process: The dry coal is fed into the rotary pyrolysis furnace through the dry coal buffer and dry coal conveying device to complete the pyrolysis process. The heat source used by the rotary pyrolysis furnace is the high-temperature hot air generated by the hot air furnace. After pyrolysis, high-temperature semi-coke and raw coal gas are obtained. The high-temperature semi-coke and raw coal gas are discharged through corresponding pipelines for subsequent treatment. The specific control process is as follows: Input the control parameters of the dry coal pyrolysis process into the central controller in advance, including the dry coal buffer level setting value, the raw gas pressure setting value, the hot air inlet temperature setting value, the semi-coke discharge temperature setting value, and the discharge pipe level setting value, and then automatically control the dry coal pyrolysis process through the central controller; a. Ensure that the material level of dry coal in the dry coal buffer bin is within the set range by adjusting the dry coal transfer device; b. Ensure that the raw gas pressure is controlled within the set range by adjusting the opening of the gas induced draft fan and the raw gas flow regulating valve; c. Ensure that the semi-coke material level in the discharge pipe is controlled within the set range by adjusting the semi-coke conveying device; d. Ensure that the semi-coke discharge temperature is controlled within the set range by adjusting the rotary pyrolysis furnace; e. By adjusting the opening of the fuel flow control valve, the fuel flow is controlled at the fuel flow target value. The fuel flow target value is calculated in real time by the central controller based on the feedback values ​​of fuel-related parameters. Fuel-related parameters include fuel calorific value, raw coal flow, raw coal moisture, dried coal moisture, fuel pressure and fuel temperature; f. By adjusting the opening of the combustion air flow control valve, the combustion air flow is controlled at the combustion air target value. The combustion air target value is calculated in real time by the central controller based on the feedback values ​​of the combustion air related parameters, including the fuel calorific value, fuel flow, combustion air pressure and combustion air temperature; g. By adjusting the exhaust fan, the exhaust gas flow rate is controlled at the exhaust gas target value. The exhaust gas target value is calculated in real time by the central controller based on the feedback values ​​of the exhaust gas related parameters. The exhaust gas related parameters include fuel calorific value, fuel flow rate, combustion air flow rate, exhaust gas pressure and exhaust gas temperature; h. Control the hot air inlet temperature of the rotary pyrolysis furnace within the target range by adjusting the circulating fan.

10. The low-rank coal pyrolysis control method according to claim 9, characterized in that: During the raw coal drying control process, the tail gas thermometer 1, tail gas thermometer 2 and oxygen concentration meter are interlocked through the central controller. When the tail gas temperature measured by tail gas thermometer 1 and tail gas thermometer 2 exceeds the limit value, or the oxygen concentration in the tail gas measured by the oxygen concentration meter exceeds the limit value, an automatic alarm is triggered and the nitrogen shut-off valve is automatically opened to protect the system.

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