CN-119799353-B - External combustion external heating type pulverized coal pyrolysis system and pulverized coal pyrolysis method

Abstract

The invention relates to an external combustion external heating type pulverized coal pyrolysis system and a pulverized coal pyrolysis method, wherein the external combustion external heating type pulverized coal pyrolysis system comprises a coal carbonization device, a smoke heat exchange system and a raw gas system, the smoke heat exchange system comprises an external gas combustion furnace, a high-temperature smoke distribution system and a smoke blending temperature control system, the raw gas system comprises a raw gas cooling and collecting system and a raw gas purifying system, the coal carbonization device adopts a three-stage structure of a low-temperature pyrolysis drying section, a medium-temperature pyrolysis section and a quality-improving coal cooling section, waste gas generated by combustion of coal gas in the external gas combustion furnace is introduced into the medium-temperature pyrolysis section and the high-temperature pyrolysis section to transfer heat indirectly, so that step pyrolysis of raw material pulverized coal is realized, the medium-temperature pyrolysis section and the high-temperature pyrolysis drying section are controllable in inlet smoke temperature, the equipment service life is prolonged, the product quality is stabilized, and the method can realize the pulverized coal pyrolysis continuously and stably, and the product quality is good, and the investment rate is high.

Inventors

• BAI BIN
• XIAO JIANSHENG
• YANG JUNFENG
• LIU HONGCHUN
• Cai Chengdai
• ZHANG TIANYU
• LIU QINGDA

Assignees

• 中冶焦耐(大连)工程技术有限公司

Dates

Publication Date

20260512

Application Date

20250116

Claims (6)

1. 1. A pulverized coal pyrolysis method is realized based on an external combustion external heating type pulverized coal pyrolysis system; the external combustion external heating type pulverized coal pyrolysis system is characterized by comprising a coal carbonization device, a flue gas heat exchange system and a raw gas system; the coal carbonization device is sequentially provided with a low-temperature pyrolysis drying section, a medium-temperature pyrolysis section and a upgraded coal cooling section from top to bottom; the flue gas heat exchange system comprises an external gas combustion furnace, a high-temperature flue gas distribution system and a flue gas blending temperature control system, wherein the raw gas system comprises a raw gas cooling gas collecting system and a raw gas purifying system, the highest heat-resistant temperature of the low-temperature pyrolysis drying section is higher than 900 ℃, the highest heat-resistant temperature of the medium-high-temperature pyrolysis drying section is higher than 1400 ℃, a plurality of coal circulation areas and flue gas circulation areas in the medium-high-temperature pyrolysis drying section, the medium-high-temperature pyrolysis drying section and the upgraded coal cooling section are arranged at intervals to form a coal circulation channel and a flue gas circulation channel which are communicated up and down, a flue gas inlet of the medium-high-temperature pyrolysis section is connected with a high-temperature flue gas outlet of an external gas combustion furnace through the high-temperature flue gas distribution system, a mixed flue gas outlet of the medium-high-temperature pyrolysis section is connected with a high-temperature flue gas inlet of the flue gas blending temperature control system, a mixed flue gas outlet of the flue gas blending temperature control system is connected with a flue gas inlet of the low-temperature pyrolysis drying section, a low-temperature pyrolysis drying section flue gas outlet is connected with the purifying system through an outlet flue gas pipeline, the outlet low-temperature pyrolysis drying section is additionally connected with a flue gas inlet Wen Huipei of the blending temperature control system, a plurality of low-temperature flue gas outlets of low-temperature pyrolysis flue gas inlets, and a plurality of high-temperature pyrolysis flue gas outlets Jie Duan are respectively, the raw gas cooling and collecting system is connected with the raw gas purifying system, an ammonia water spraying, cooling and washing device is arranged in a raw gas main pipe of the raw gas cooling and collecting system, the raw gas purifying system is connected with an outer gas conveying pipeline through a purified gas pipeline, a gas fan is arranged on the purified gas pipeline, the purified gas pipeline is additionally connected with a gas inlet pipeline of an external gas combustion furnace, and the gas inlet pipeline is additionally connected with a lean gas pipeline; the pulverized coal pyrolysis method comprises the following steps: 1) Raw material pulverized coal with granularity less than 13mm enters a low-temperature pyrolysis drying section of a coal carbonization device through a furnace top coal bin, descends along a coal circulation channel, and carries out countercurrent indirect heat exchange with smoke in the smoke circulation channel to realize drying and low-temperature carbonization, the pulverized coal after low-temperature carbonization enters a medium-temperature pyrolysis Duan Jinhang for pyrolysis and upgrading, the generated upgraded coal enters a upgraded coal cooling section for cooling to normal temperature under the action of gravity, and the cooled upgraded coal is subjected to coke discharging rate control by a coke pusher and is transported outwards by a semicoke conveying device; 2) Raw material pulverized coal is subjected to low-temperature carbonization in a low-temperature pyrolysis drying section, raw gas, tar and moisture generated by pyrolysis in a medium-high-temperature pyrolysis section are collected in sections and are unified to be converged into a raw gas cooling and collecting system, and then purified by a raw gas purifying system to obtain high-heat-value gas, wherein after being pressurized by a gas fan, part of the gas is taken as outward gas, and the other part of the gas is taken as return gas to burn rich gas and is sent to an external gas combustion furnace; 3) The gas raw material of the external gas combustion furnace comprises rich gas and/or external lean gas which are combusted by the back furnace, the external gas combustion furnace controls combustion heat through a gas regulating valve of the combustion furnace, the temperature of generated high-temperature flue gas is controlled to be 1100-1400 ℃, the high-temperature flue gas is uniformly distributed into each flue gas circulation area of the middle-temperature pyrolysis section through a high-temperature flue gas distribution system, heat exchange is performed between the middle-temperature pyrolysis section and tail coal in the coal circulation area, the temperature of the outlet flue gas of the middle-temperature pyrolysis section is controlled to be 800-950 ℃, the outlet flue gas of the middle-temperature pyrolysis section is mixed with low-temperature Wen Huipei flue gas through a flue gas mixing temperature control system, the temperature of the inlet flue gas of the middle-temperature pyrolysis drying section is controlled to be 600-900 ℃, the temperature of the mixed gas entering the low-temperature pyrolysis drying section is subjected to countercurrent indirect heat exchange with raw material tail coal, the outlet flue gas of the low-temperature pyrolysis drying section is controlled to be 150-250 ℃, part of the outlet flue gas of the low-temperature pyrolysis drying section is boosted by a flue gas fan, the other part of the flue gas enters the flue gas purification system as low-temperature mixing temperature control system, and the flue gas purification system comprises a flue gas desulfurization and denitration system.
2. 2. The pulverized coal pyrolysis method according to claim 1, wherein a top feed inlet of the coal carbonization device is provided with a furnace top feed bin, and a bottom discharge outlet is provided with a coke pusher and a semicoke conveying device.
3. 3. The pulverized coal pyrolysis method according to claim 1, wherein the low-temperature pyrolysis drying section is made of more than one material selected from carbon steel, cast steel, heat-resistant stainless steel and silicon carbide ceramics, the medium-temperature pyrolysis section is made of more than one material selected from refractory materials, cast steel, heat-resistant stainless steel and silicon carbide ceramics, and a plurality of baffle plates are respectively arranged in flue gas circulation channels of the low-temperature pyrolysis drying section and the medium-temperature pyrolysis section.
4. 4. The pulverized coal pyrolysis method according to claim 1, wherein the high-temperature flue gas distribution system comprises a high-temperature flue gas conveying pipe and a high-temperature flue gas distribution pipe which are horizontally arranged, one end of the high-temperature flue gas conveying pipe is connected with a high-temperature flue gas outlet of an external gas combustion furnace through a high-temperature flue gas pipeline, the other end of the high-temperature flue gas conveying pipe is connected with the high-temperature flue gas distribution pipe, a plurality of high-temperature flue gas distribution holes are arranged at the top of the high-temperature flue gas distribution pipe in a one-to-one correspondence with a plurality of flue gas areas of a medium-high-temperature pyrolysis section, and the high-temperature flue gas distribution pipe is of a gradual-change structure with gradually reduced sectional area along the flow direction of the high-temperature flue gas.
5. 5. The pulverized coal pyrolysis method according to claim 4, wherein the high-temperature flue gas conveying pipe is provided with a high-temperature flue gas temperature detection device and a high-temperature flue gas pressure detection device.
6. 6. The pulverized coal pyrolysis method according to claim 1, wherein the flue gas blending temperature control system comprises a first section of flue gas pipeline, a blending sleeve, a blending flue gas regulating valve, a second section of flue gas pipeline, a first section of flue gas temperature detection device and a second section of flue gas temperature detection device, one end of the first section of flue gas pipeline is connected with a middle-high temperature pyrolysis section flue gas outlet, the other end of the first section of flue gas pipeline is connected with the second section of flue gas pipeline through a high-temperature expansion joint, the blending sleeve is provided with a low Wen Huipei flue gas inlet, the blending sleeve is provided with a blending gas regulating valve at a low Wen Huipei flue gas inlet, the other end of the second section of flue gas pipeline is connected with a low-temperature pyrolysis drying section flue gas inlet, the first section of flue gas pipeline is provided with the first section of flue gas temperature detection device, and the second section of flue gas pipeline is provided with the second section of temperature detection device.

Description

External combustion external heating type pulverized coal pyrolysis system and pulverized coal pyrolysis method Technical Field The invention relates to the technical field of low-rank coal carbonization, in particular to an external combustion external heating type pulverized coal pyrolysis system and a pulverized coal pyrolysis method. Background The low-rank coal has the characteristics of abundant reserves, shallower burial depth and lower mining economic cost, and the geological reserve of the global low-rank coal is up to 4 trillion tons and accounts for 40% of the total reserve of the global coal according to statistics. In China, development and utilization of high-quality coal types such as bituminous coal, anthracite and the like tend to be saturated, and large-scale development and utilization of low-rank coal are started just. Currently, an internal heating type vertical furnace is generally adopted in the industrial field to upgrade and process low-rank coal, and the internal heating type vertical furnace relates to a process of injecting mixed gas of coal gas and air into the furnace to burn and dry distillation. However, the amount of gas produced in this process is large but the quality of gas is not high, and the proportion of ineffective components such as nitrogen exceeds 50%. The low-quality coal gas can only be sent to a power plant for combustion power generation, and cannot be further used for deep processing to produce chemicals with high added value. In addition, because of the technical characteristics of the internal heating type vertical furnace, the pulverized coal with the particle size smaller than 13mm cannot be treated. So far, the efficient quality-classifying cascade utilization of the pulverized coal is still a difficult problem which prevents the realization of industrial application of low-rank coal. The Chinese patent application with publication number of CN105018120A discloses a continuous carbonization process and device for low-order powdered coal, the low-order powdered coal enters an external heating type continuous carbonization refractory furnace through a double-seal feeding device and a material buffering bin, raw gas is collected through a gas collecting device and a gas collecting cavity and is led out by a gas collecting system, and carbonized furnace burden is discharged through a discharging device. The method realizes the continuous carbonization process of using low-order pulverized coal as a raw material in an externally heated continuous carbonization furnace, raw gas generated in the carbonization process can be rapidly led out, the light oil yield and the gas heat value can be improved, the pulverized coke can be uniformly and continuously discharged in the coke discharging process, and the quality of semicoke can be controlled and regulated. However, the furnace body is of a refractory brick structure, so that the heat transfer efficiency of the device is low, the unit productivity is small, and the overall investment is large. The Chinese patent application with publication number of CN112708434A discloses a continuous low-rank coal pyrolysis furnace with modular combination units, which can be used for processing and producing low-rank coal semicoke, and has better pertinence and applicability to small-grain-size coal and pulverized coal. The pyrolysis furnace is composed of a plurality of furnace body units which are assembled in a row, each unit is a furnace body with complete functions, and each unit is structurally composed of a plurality of detachable functional modules. The module structure ensures that the whole coke oven has the performances of disassembly and replacement, is beneficial to reducing the construction cost and is convenient to overhaul. However, the refractory prefabricated module adopted by the method is difficult to wholly pour, has a complex structure and low yield, and is difficult to popularize in practical industrial application. The Chinese patent application with publication number of CN111518581A discloses an external heating type pulverized coal carbonization method and device with upright multi-tube sectional air guide, which utilizes a tubular carbonization process, adopts a tower-type sectional upright tubular structure to treat raw coal, and sequentially comprises a section of drying, a section of carbonization and a section of cooling process from top to bottom. The device can promote the quality of semicoke, and heat exchange efficiency is high, improves resource utilization and productivity. But the production of high-temperature section equipment is unstable due to the characteristic of the heat-resistant material of the carbonization section. Disclosure of Invention The invention provides an external combustion external heating type pulverized coal pyrolysis system and a pulverized coal pyrolysis method, wherein a coal carbonization device adopts a three-stage structure of a low-temperature pyrolysis dryi