Warehouse type hot air powder feeding system

Abstract

The utility model relates to a storage type hot air powder feeding system, which solves the problems that the existing system is high in transformation cost and not beneficial to energy conservation and consumption reduction, and adopts the technical scheme that the storage type hot air powder feeding system comprises an air pre-heater and a bag-type dust collector which are sequentially connected with an outlet flue of a hearth, a hot air outlet of the air pre-heater is connected with the steel ball mill, the coarse powder separator and the fine powder separator sequentially through a hot air door and a main air door, a pulverized coal outlet of the fine powder separator is sequentially connected with a pulverized coal bin, a powder feeder and an air-powder mixer, and an exhaust gas outlet of the fine powder separator is connected with a recirculation air door, a temperature adjusting air door and an exhaust gas adjusting door. The recirculation air door is connected with the steel ball mill; the temperature adjusting air door is connected with a primary air nozzle of the hearth through a primary air door and an air powder mixer in sequence; and the exhaust gas adjusting door is connected with a bin of the bag-type dust collector. The device is energy-saving, environment-friendly, low in transformation cost and high in safety and reliability.

Description

Technical Field

[0001] The utility model relates to the field of power plant fuel equipment, and specifically relates to a storage type hot air powder feeding system Background Art

[0002] Most of the existing medium and small boilers adopt a storage type pulverizing system, mainly for the preparation of low volatile coal types. The storage type pulverizing system is divided into two types: hot air powder feeding and exhaust gas powder feeding. For low volatile coal types, hot air powder feeding is selected. The exhaust gas after the fine powder separator is used as the tertiary air and sent into the furnace. This part of the exhaust gas with high moisture, low temperature and containing 10-15% of ultrafine coal powder has a great impact on the boiler heating surface. Especially during the start-up and shutdown process of the pulverizing system, the boiler operation is extremely unstable, and various indicators (steam parameters, pollutant emission indicators, furnace oxygen content, furnace pressure, etc.) all fluctuate violently

[0003] To solve the above technical problems, the patent No. CN209857034U discloses an efficient and low-emission storage type hot air powder feeding system. A ceramic filter is connected after the coarse powder separator. After being filtered by the ceramic filter, clean exhaust gas can be obtained. This part of the gas is divided into three streams. The last stream of gas is not sent back to the furnace as the tertiary air, but is discharged through the exhaust gas regulating door, avoiding various problems brought by the return of the tertiary air to the furnace and effectively solving the above problems

[0004] The key point for the tertiary air to be discharged in the above technical solution lies in the use of a ceramic filter. In actual application, due to the high procurement cost of the ceramic filter, the system cost has increased significantly, making it difficult to be actually promoted Summary of the Invention

[0005] The purpose of the utility model is to solve the above technical problems and provide a storage type hot air powder feeding system with energy conservation, environmental protection, low transformation cost and high safety and reliability

[0006] The storage type hot air powder feeding system includes an air preheater and a bag filter connected in sequence to the outlet flue of the furnace. The hot air outlet of the air preheater is connected to a steel ball mill, a coarse powder separator and a fine powder separator through a hot air door and a main air door in sequence. The coal powder outlet of the fine powder separator is connected to a coal powder bin, a coal feeder and a pulverized coal-air mixer in sequence. The exhaust gas outlet of the fine powder separator is respectively connected to a recirculation air door, a temperature regulating air door and an exhaust gas regulating door. Among them, the recirculation air door is connected to the steel ball mill; the temperature regulating air door is connected to the primary air nozzle of the furnace through a primary air door, a pulverized coal-air mixer in sequence; the exhaust gas regulating door is connected to the chamber of the bag filter

[0007] The dust collector has a plurality of chambers connected in series, and the exhaust gas regulating door is connected to the last chamber

[0008] The fine powder outlet at the bottom of the third chamber is connected to the reburning nozzle of the furnace

[0009] The coarse powder outlet of the said coarse powder separator is connected to the steel ball mill.

[0010] Beneficial effects:

[0011] In the present utility model, a fine powder separator is used to replace the ceramic filter. The exhausted gas from the fine powder separator is no longer clean exhausted gas, but exhausted gas containing ultra-fine coal powder. The exhausted gas from the fine powder separator is divided into three streams. The first stream and the second stream are still used as desiccant and for adjusting the temperature of the primary air respectively; the third stream of exhausted gas is neither directly discharged to the outside nor directly sent into the furnace, but is ingeniously discharged into the bag filter for filtration and further drying to separate ultra-fine coal powder and gas. The filtered gas is then discharged to the outside through the bag filter. The internal flue gas environment of the bag filter avoids the risks of spontaneous combustion and deflagration that may occur when using air to make powder and collect the tertiary air; after the separated ultra-fine coal powder is collected, it is sent back to the furnace as reburning fuel. Compared with the original amount of the tertiary air returned to the furnace, the amount of air returned to the furnace can be reduced from 25% of the total combustion air volume to less than 5%. Combined with the original staged combustion, it can effectively reduce the nitrogen oxide emissions by 70%. At the same time, after the filtered gas is discharged to the outside, the amount of external discharge reduces the amount of oxygen required for furnace combustion, and corresponding air needs to be supplemented into the air preheater. At this time, the same amount of cold air can be supplemented into the air preheater for indirect heat exchange with the furnace flue gas. While supplementing oxygen, the temperature of the flue gas after heat exchange is further reduced, and the temperature drop can reach 13 - 20 °C, achieving two goals with one action. The present utility model is energy-saving and environment-friendly, with low transformation cost and high safety and reliability. Description of the drawings

[0012] Figure 1 It is a system diagram of the present utility model.

[0013] Among them, 1 - steel ball mill, 2 - coarse powder separator, 3 - fine powder separator, 4 - powder exhauster, 5 - temperature regulating damper, 6 - recirculation damper, 7 - primary air damper, 8 - hot air damper, 9 - primary air nozzle, 10 - main damper, 11 - coal feeder, 12 - air-powder mixer, 13 - coal feeder, 14 - raw coal bunker, 15 - pulverized coal bunker, 16 - air preheater, 17 - forced draft fan, 18 - exhausted gas regulating damper, 19 - furnace, 20 - reburning nozzle, 21 - Roots blower, 22 - bag filter, 22.1 - #1 chamber, 22.2 - #2 chamber, 22.3 - #3 chamber. Specific implementation manners

[0014] The present utility model will be further explained below in conjunction with the drawings:

[0015] System embodiment: Refer to Figure 1, the outlet flue of the furnace 19 is connected to the air preheater 16. The air preheater 16 is an indirect heat exchanger. A forced draft fan 17 is provided at the cold air inlet of the air preheater 16. The hot air outlet of the air preheater 16 is successively connected to the steel ball mill 1, the coarse powder separator 2, and the fine powder separator 3 through the hot air damper 8 and the main damper 10; the coal powder outlet of the fine powder separator 3 is successively connected to the coal powder silo 15, the coal feeder 11, and the air-coal mixer 12. The exhaust gas outlet of the fine powder separator 3 is respectively connected to the temperature regulating damper 5, the recirculation damper 6, and the exhaust gas regulating damper 18. Among them, the recirculation damper 6 is connected to the steel ball mill 1 through the main damper 10. The temperature regulating damper 5 is successively connected to the primary air damper 7, the air-coal mixer 12, and the primary air nozzle 9 of the furnace 19; the coarse powder outlet of the coarse powder separator 2 is connected to the steel ball mill 1;

[0016] The bag filter 22 has 3 chambers connected in series, namely the #1 chamber 22.1, the #2 chamber 22.2, and the #3 chamber 22.3. The exhaust gas regulating damper 18 is connected to the ash hopper of the third #3 chamber 22.3 of the bag filter through a pipeline. The fine coal powder and ash mixture collected in the #3 chamber 22.3 is connected to the reburning nozzle 20 of the furnace 19 through the roots blower 21.

[0017] Process:

[0018] The furnace flue gas from the furnace 19 is discharged into the air preheater 16 to exchange heat with the cold air introduced by the forced draft fan 17. After heat exchange, the flue gas enters the bag filter 22 for dust removal and then is discharged to the outside. The preheated hot air is divided into two streams by the air preheater 16. One stream of hot air (accounting for 25% by volume of the total hot air volume) passes through the hot air damper 8, adjusts the temperature after mixing with the first stream of clean exhausted gas from the recirculation damper 6, and then passes through the main damper 10 to be used as a desiccant to dry the raw coal fed into the steel ball mill 1. Then it carries the pulverized coal after grinding and enters the coarse powder separator 2 for primary filtration. The separated coarse powder is returned to the steel ball mill 1, and the separated fine powder and desiccant enter the fine powder separator 3 for secondary filtration together. The qualified pulverized coal separated is sent to the pulverized coal bin 15 and the coal feeder 11, and then enters the air-powder mixer 12, and finally is sprayed into the furnace 19 through the primary air nozzle 9. The exhausted gas (containing a small amount of ultra-fine pulverized coal) separated by the fine powder separator 3 is divided into three streams after passing through the exhaust fan 4. The first stream of exhausted gas (accounting for 10 - 40% by volume of the total exhausted gas volume) passes through the recirculation damper 6 and mixes with the first stream of hot air to adjust the temperature of the desiccant and then is sent into the steel ball mill 1. The second stream of exhausted gas (accounting for 5 - 10% by volume of the total exhausted gas volume) passes through the temperature adjustment damper 5, mixes with the second stream of hot air, and then passes through the primary air damper 7 to mix with the qualified pulverized coal in the air-powder mixer 12 and is sprayed out from the primary air nozzle 9 of the furnace. The third stream of exhausted gas is sent to the 3# chamber 22.3 of the bag filter 22 through the exhausted gas adjustment damper 18. The mixture of ultra-fine pulverized coal and fly ash collected in the 3# chamber 22.3 of the bag filter 22 is sent into the reburning nozzle 20 of the furnace 19 by the roots blower 21. The air-powder concentration is controlled at 1:10 - 30 (kg / kg). The ultra-fine pulverized coal is used as the reburning fuel to reduce the generation of nitrogen oxides. The exhausted gas separated by the bag filter 22 is discharged to the outside. At the same time, cold air is supplemented into the air preheater 16, and the supplement amount is the external discharge amount of the third stream of exhausted gas.

[0019] Compared with the existing system, after being processed by the system of the present utility model, the temperature of the furnace flue gas discharged from the air preheater 16 drops by 13 - 20 °C, effectively recovering heat energy. The unburned rate in the furnace with the same fuel is reduced by more than 40%, the nitrogen oxide content is reduced by 70%, and the gas volume of the third stream of exhausted gas sent into the furnace 19 is reduced from 25% of the total combustion air volume to less than 5%. As a result, the air flow entering the furnace from the reburning nozzle 20 is in a severely oxygen-deficient state, achieving the purpose of reburning and reducing nitrogen oxides, and the transformation cost is saved by 60%.

Claims

1. A storage type hot air powder feeding system, which includes an air preheater and a bag filter connected in sequence to the outlet flue of the furnace, is characterized in that, The hot air outlet of the air preheater is successively connected to the ball mill, the coarse powder separator and the fine powder separator through the hot air damper and the main air damper. The coal powder outlet of the fine powder separator is successively connected to the coal powder silo, the coal feeder and the air powder mixer. The exhaust gas outlet of the fine powder separator is respectively connected to the recirculation damper, the temperature regulating damper and the exhaust gas regulating damper. Among them, the recirculation damper is connected to the ball mill; the temperature regulating damper is successively connected through the primary air damper, the air powder mixer and the primary air nozzle of the furnace; the exhaust gas regulating damper is connected to the chamber of the bag filter.

2. The storage type hot air powder feeding system according to claim 1, characterized in that, The dust collector has a plurality of chambers connected in series, and the exhaust gas regulating damper is connected to the last chamber.

3. The storage type hot air powder feeding system according to claim 2, wherein The fine powder outlet at the bottom of the third chamber is connected to the reburning nozzle of the furnace.

4. The storage type hot air powder feeding system according to claim 2, wherein The coarse powder outlet of the coarse powder separator is connected to the ball mill.

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