A pulverized coal bunker system for optimizing boiler start-up and shut-down and a method of using the same

Abstract

The application discloses a kind of coal powder bin system for optimizing boiler start-stop and its use method, the coal powder bin system, including A powder bin, B powder bin, carbon dioxide supply device and control unit, the A powder bin and B powder bin are equipped with powdering unit and powder feeding unit, A powder bin and B powder bin are communicated with carbon dioxide supply device, A powder bin is equipped with pressure sensor and temperature sensor, the control unit is electrically connected with carbon dioxide supply device, powdering unit, powder feeding unit, pressure sensor and temperature sensor respectively.The coal powder bin system and its use method of the application are used, while the efficiency of boiler start-stop is considered, the fuel and electric energy consumption of boiler start-stop are saved.

Description

Technical Field

[0001] This invention belongs to the field of boiler pulverized coal silo technology, specifically relating to a pulverized coal silo system for optimizing boiler start-up and shutdown and its usage method. Background Technology

[0002] Current power plant boilers (such as 300MW boilers, which are designed with a single furnace, L-shaped layout, and balanced ventilation; the boiler adopts an all-steel frame structure and semi-open-air layout; burns bituminous coal and lean coal, with solid ash discharge; use direct-flow burners with tangential combustion at the four corners; the combustion system has five layers of burners, from bottom to top: layers A, B, C, D, and E. The four burners in layer A are all micro-oil ignition burners, equipped with corresponding small gasification oil guns. After the boiler is ignited, pulverized coal is immediately added to the micro-oil ignition burners in layer A, which can save a lot of start-up oil consumption) mostly adopt a central storage pulverizing system. Qualified pulverized coal is transferred and stored in the pulverized coal silo, which allows the pulverizing system and the combustion system to operate relatively independently, enhancing the system's safety and flexibility. However, the existence of the pulverized coal silo also brings many potential dangers and inconveniences to the central storage pulverized coal system: 1. During boiler shutdown, the pulverized coal silo needs to be emptied while the boiler is in oil-filled mode, which prolongs the boiler shutdown time and wastes a lot of fuel oil and electricity. Especially in the case of unplanned emergency shutdown, the large amount of pulverized coal stored in the silo poses a risk of spontaneous combustion and explosion, which is a huge safety hazard. 2. Even after consuming a large amount of fuel oil and electricity, the pulverized coal accumulated in the dead corners of the silo is still difficult to burn off completely. If this accumulated pulverized coal is not controlled, it still poses a risk of spontaneous combustion or even explosion. This accumulated pulverized coal can only be removed manually, which not only wastes all the pulverized coal and seriously pollutes the environment, but also requires a lot of manpower and takes a long time to clean, which also creates an important safety hazard. 3. Currently, boiler startup mainly uses a combination of primary air heater and micro-oil ignition burner. Due to the low output of the primary air heater, the ignition and pulverizing system remains in a warm-mill or low-output state for about 1.5 hours after boiler ignition. At this time, there is no pulverized coal in the pulverizer to supply the micro-oil ignition burner in layer A, and the boiler is in a pure oil combustion state. Not only is the boiler water temperature rise extremely slow, but the fuel consumption is also extremely high, prolonging the boiler startup time and increasing the fuel and electricity consumption during boiler startup.

[0003] In summary, for boiler units based on the existing pulverized coal silo system, the pulverized coal silo needs to be emptied every time the boiler is shut down. At the initial stage of ignition, there is no pulverized coal to burn in the silo. This boiler start-up and shutdown mode prolongs the start-up and shutdown time and wastes a lot of fuel oil and electricity. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a pulverized coal silo system for optimizing boiler start-up and shutdown and its usage method, so as to save fuel oil and electricity consumption during boiler start-up and shutdown while taking into account boiler start-up and shutdown efficiency.

[0005] The present invention solves the above problems through the following technical means:

[0006] A pulverized coal storage system for optimizing boiler start-up and shutdown includes a pulverized coal storage compartment A, a pulverized coal storage compartment B, a carbon dioxide supply device, and a control unit. Both the pulverized coal storage compartment A and B are equipped with a pulverizing unit and a pulverizing unit, respectively. Both the pulverized coal storage compartment A and B are connected to the carbon dioxide supply device. The pulverized coal storage compartment A is equipped with a pressure sensor and a temperature sensor. The control unit is electrically connected to the carbon dioxide supply device, the pulverizing unit, the pulverizing unit, the pressure sensor, and the temperature sensor, respectively.

[0007] Furthermore, the carbon dioxide supply device includes a carbon dioxide supply end, a carbon dioxide conveying main pipe, and a carbon dioxide conveying branch pipe. The carbon dioxide conveying main pipe is connected to the carbon dioxide supply end, and the A powder silo and the B powder silo are respectively connected to the carbon dioxide conveying main pipe through the carbon dioxide conveying branch pipe.

[0008] Furthermore, the carbon dioxide supply end includes a high-pressure carbon dioxide supply end and a low-pressure carbon dioxide supply end.

[0009] A method for using the above-mentioned pulverized coal silo system: During boiler shutdown, the pulverized coal in silo B is burned out, while low-temperature pulverized coal is left in silo A. The temperature of the pulverized coal reserved in silo A is 60-65℃, and the height of the pulverized coal is 0.5-1 meter. After boiler shutdown, silo A is sealed, and the temperature and pressure inside silo A are monitored in real time to maintain a slight positive pressure. At the same time, carbon dioxide is introduced into silo A to inhibit the low-temperature oxidation reaction of the pulverized coal. After the boiler is restarted and ignited, the reserved pulverized coal in silo A is added.

[0010] Furthermore, upon receiving the shutdown order, 6 hours before the boiler is shut down, the pulverizing unit of the B pulverizing silo is evacuated and shut down. When the unit is under high load, the speed of the feeder of the B pulverizing silo feeding unit is increased first to evacuate the B pulverizing silo. According to the unit load and shutdown schedule, the pulverizing unit of the A pulverizing silo is shut down in a timely manner. 2 hours before shutdown, the outlet temperature of the A pulverizing unit is controlled between 60-65 degrees Celsius. When the boiler is shut down, 0.5-1.0 meters of low-temperature pulverized coal is left in the A pulverizing silo.

[0011] Furthermore, immediately after shutdown, implement pulverized coal silo sealing measures, closing silo A to isolate it from the outside environment. After the sealing measures are completed, introduce carbon dioxide gas into silo A to maintain a slight positive pressure, preventing humid air from being drawn into silo A through any leaks. Monitor the temperature and air pressure of silo A in real time. If the temperature of silo A reaches 100℃, increase the carbon dioxide injection rate, replacing the silo with low-pressure carbon dioxide gas to achieve a carbon dioxide volume fraction of 31%. 31% carbon dioxide has a good inertizing effect on the low-temperature oxidation reaction of pulverized coal, effectively preventing the temperature of silo A from rising further. If the temperature of silo A rises further to 160℃, increase the carbon dioxide volume fraction to 50%. 50% carbon dioxide can significantly inhibit the low-temperature oxidation reaction of pulverized coal. Increasing the carbon dioxide volume fraction in silo A through replacement and inhibiting the low-temperature oxidation reaction of pulverized coal can effectively prevent spontaneous combustion of pulverized coal. In case of fire, introduce high-pressure carbon dioxide for fire extinguishing.

[0012] Furthermore, before boiler ignition, the coal feeder plate of the coal feeding unit in pulverized coal silo A is opened to 10% of its opening. After ignition, the coal is fed into the micro-oil ignition burners one by one diagonally. The coal powder reserved in pulverized coal silo A is sufficient for the initial startup of the micro-oil burners for 1.5 hours. 1.5 hours after ignition, the ignition and pulverizing system is already operating normally and can continuously supply the coal powder required during boiler startup. The reserved small amount of coal powder ensures a continuous supply of coal powder to the micro-oil burners throughout the entire boiler startup process. Coal powder is added as soon as ignition is successful, which shortens the boiler startup time and reduces boiler startup oil consumption.

[0013] The beneficial effects of this invention are as follows: This application discloses a pulverized coal silo system and its usage method for optimizing boiler start-up and shutdown. The pulverized coal silo system includes an A silo, a B silo, a carbon dioxide supply device, and a control unit. Both the A and B silos are equipped with a pulverizing unit and a feeding unit, and both are connected to the carbon dioxide supply device. The A silo is equipped with a pressure sensor and a temperature sensor. The control unit is electrically connected to the carbon dioxide supply device, the pulverizing unit, the feeding unit, the pressure sensor, and the temperature sensor, respectively. By employing the pulverized coal silo system and its usage method of this application, boiler start-up and shutdown efficiency is achieved while saving fuel and electricity consumption during boiler start-up and shutdown. Attached Figure Description

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0015] Figure 1 This is a schematic diagram of a preferred embodiment of the present invention;

[0016] Figure 2 This is a schematic diagram of powder hopper A;

[0017] Figure 3 This is a schematic diagram showing the distribution of pressure sensors in powder silo A;

[0018] Figure 4 This is a schematic diagram showing the distribution of temperature sensors in powder silo A. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings, such as... Figures 1 to 4 The pulverized coal storage system of the present invention for optimizing boiler start-up and shutdown includes a pulverized coal storage silo A (6), a pulverized coal storage silo B (7), a carbon dioxide supply device, and a control unit. Both pulverized coal storage silos A and B are equipped with a pulverizing unit (5) and a feeding unit (8). Both pulverized coal storage silos A and B are connected to the carbon dioxide supply device. The pulverized coal storage silo A is equipped with a pressure sensor (9) and a temperature sensor (10). The control unit is electrically connected to the carbon dioxide supply device, the pulverizing unit, the feeding unit, the pressure sensor, and the temperature sensor, respectively. The carbon dioxide supply device includes a carbon dioxide supply end, a main carbon dioxide delivery pipe (3), and a branch carbon dioxide delivery pipe (4). The main carbon dioxide delivery pipe is connected to the carbon dioxide supply end. The pulverized coal storage silos A and B are respectively connected to the main carbon dioxide delivery pipe via the branch carbon dioxide delivery pipes. The carbon dioxide supply end includes a high-pressure carbon dioxide supply end (2) and a low-pressure carbon dioxide supply end (1).

[0020] In practice, the number of powder-making units and powder-feeding units is adjusted according to the actual situation, and the powder-feeding pipes, powder feeders, etc. equipped in the powder-feeding units are also adjusted according to the actual situation; each pipe is equipped with valves, baffles and other components as required; in this embodiment, powder bins A and B are each equipped with two powder-making units.

[0021] In practice, the pulverized coal ground by the corresponding pulverizing unit enters the A pulverized coal bin and the B pulverized coal bin respectively; the pulverized coal in the A and B pulverized coal bins enters the corresponding primary pulverized coal pipe after passing through their respective pulverizers, and is blown by the primary air conveyed by the primary air conveying pipe to the corresponding burner for ignition and combustion.

[0022] This embodiment also discloses a method for using the above-mentioned pulverized coal silo system. During the shutdown process, the pulverized coal in silo B is burned out, while low-temperature pulverized coal is left in silo A. The temperature of the pulverized coal reserved in silo A is 60-65℃, and the height of the pulverized coal is 0.5-1 meter. After the shutdown, silo A is sealed, and the temperature and pressure inside silo A are monitored in real time to maintain a slight positive pressure. At the same time, carbon dioxide is introduced into silo A to inhibit the low-temperature oxidation reaction of the pulverized coal. After the boiler is restarted and ignited, the reserved pulverized coal in silo A is added.

[0023] Upon receiving the shutdown order, 6 hours before the boiler is shut down, the pulverizing unit of the B pulverizing silo is evacuated and shut down. When the unit is under high load, the speed of the feeder of the B pulverizing silo feeding unit is increased first, and the B pulverizing silo is emptied first. According to the unit load and shutdown schedule, the pulverizing unit of the A pulverizing silo is shut down in a timely manner. 2 hours before shutdown, the outlet temperature of the A pulverizing unit is controlled between 60-65 degrees Celsius. When the boiler is shut down, 0.5-1.0 meters of low-temperature pulverized coal is left in the A pulverizing silo.

[0024] Immediately after shutdown, implement pulverized coal silo sealing measures, closing silo A to isolate it from the outside environment. After sealing, introduce carbon dioxide gas into silo A to maintain a slight positive pressure, preventing humid air from being drawn into the silo through any leaks. Monitor the temperature and air pressure of silo A in real time. If the temperature reaches 100℃, increase the carbon dioxide injection rate, replacing the silo with low-pressure carbon dioxide gas to achieve a carbon dioxide volume fraction of 31%. 31% carbon dioxide has a good inertizing effect on the low-temperature oxidation reaction of pulverized coal, effectively preventing the temperature of silo A from rising further. If the temperature of silo A rises further to 160℃, increase the carbon dioxide volume fraction to 50%. 50% carbon dioxide can significantly inhibit the low-temperature oxidation reaction of pulverized coal. Increasing the carbon dioxide volume fraction in silo A through replacement and inhibiting the low-temperature oxidation reaction of pulverized coal can effectively prevent spontaneous combustion of pulverized coal. In case of fire, introduce high-pressure carbon dioxide for fire extinguishing.

[0025] Before boiler ignition, open the pulverized coal feeder plate of the pulverized coal feeding unit in pulverized coal bin A to 10% opening. After ignition, feed the pulverized coal into the micro-oil ignition burners one by one diagonally. The pulverized coal reserved in pulverized coal bin A is sufficient for the initial startup of the micro-oil burners for 1.5 hours. 1.5 hours after ignition, the ignition and pulverizing system is already operating normally and can continuously supply the pulverized coal required during boiler startup. The reserved pulverized coal ensures a continuous supply of pulverized coal to the micro-oil burners throughout the entire boiler startup process. Pulverized coal is added as soon as ignition is successful, shortening the boiler startup time and reducing boiler startup oil consumption.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method of using a pulverized coal silo system for optimizing boiler start-up and shut-down, characterized by: The pulverized coal storage system includes a pulverized coal storage silo A, a pulverized coal storage silo B, a carbon dioxide supply device, and a control unit. Both the pulverized coal storage silo A and the pulverized coal storage silo B are equipped with a pulverizing unit and a pulverizing unit. Both the pulverized coal storage silo A and the pulverized coal storage silo B are connected to the carbon dioxide supply device, the pulverizing unit, the pulverizing unit, the pressure sensor, and the temperature sensor, respectively. The carbon dioxide supply device includes a carbon dioxide supply end, a carbon dioxide conveying main pipe and a carbon dioxide conveying branch pipe. The carbon dioxide conveying main pipe is connected to the carbon dioxide supply end, and the powder silos A and B are respectively connected to the carbon dioxide conveying main pipe through the carbon dioxide conveying branch pipes. During the shutdown process, the pulverized coal in pulverized coal bin B is burned out, while low-temperature pulverized coal is left in pulverized coal bin A. The reserved pulverized coal temperature in pulverized coal bin A is 60-65℃, and the pulverized coal height is 0.5-1 meter. After shutdown, pulverized coal bin A is sealed, and the temperature and pressure inside pulverized coal bin A are monitored in real time to maintain a slight positive pressure. At the same time, carbon dioxide is introduced into pulverized coal bin A to inhibit the low-temperature oxidation reaction of pulverized coal. After restarting the boiler, the reserved pulverized coal in pulverized coal bin A is introduced. Upon receiving the shutdown order, 6 hours before the boiler is shut down, the pulverizing unit of the B pulverizing silo is evacuated and shut down. When the unit is under high load, the speed of the feeder of the B pulverizing silo feeding unit is increased to evacuate the B pulverizing silo. According to the unit load and shutdown schedule, the pulverizing unit of the A pulverizing silo is shut down in a timely manner. 2 hours before shutdown, the outlet temperature of the A pulverizing unit is controlled between 60-65℃. When the boiler is shut down, 0.5-1.0 meters of low-temperature pulverized coal is left in the A pulverizing silo. Immediately after shutdown, implement pulverized coal silo sealing measures, closing silo A to isolate it from the outside environment. After sealing, introduce carbon dioxide gas into silo A to maintain a slight positive pressure, preventing humid air from being drawn into the silo through any leaks. Monitor the temperature and air pressure of silo A in real time. If the temperature reaches 100℃, increase the carbon dioxide injection rate, replacing the silo with low-pressure carbon dioxide gas to achieve a carbon dioxide volume fraction of 31%. 31% carbon dioxide has a good inertizing effect on the low-temperature oxidation reaction of pulverized coal, effectively preventing the temperature of silo A from rising further. If the temperature of silo A rises further to 160℃, increase the carbon dioxide volume fraction to 50%. 50% carbon dioxide can significantly inhibit the low-temperature oxidation reaction of pulverized coal. Increasing the carbon dioxide volume fraction in silo A through replacement and inhibiting the low-temperature oxidation reaction of pulverized coal can effectively prevent spontaneous combustion of pulverized coal. In case of fire, introduce high-pressure carbon dioxide for fire extinguishing.

2. A method of using a pulverized coal silo system for optimizing boiler start-up and shut-down as claimed in claim 1, wherein: The carbon dioxide supply end includes a high-pressure carbon dioxide supply end and a low-pressure carbon dioxide supply end.

3. A method of using a pulverized coal silo system for optimizing boiler start-up and shut-down as claimed in claim 1, wherein: Before boiler ignition, open the pulverized coal feeder plate of the pulverized coal feeding unit in pulverized coal bin A to 10% opening. After ignition, feed the pulverized coal into the micro-oil ignition burners one by one diagonally. The pulverized coal reserved in pulverized coal bin A is enough for the micro-oil burners to burn for 1.5 hours during the initial start-up. 1.5 hours after ignition, the ignition and pulverizing system is already operating normally and can continuously supply the pulverized coal required during boiler start-up.

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