A dry pulverized coal gasification furnace

Abstract

This invention discloses a dry pulverized coal gasifier, comprising an upper furnace body, a fire-tube boiler, a lower furnace body, and a circular end cap, connected sequentially from top to bottom. Advantages: The lower furnace body has a first coal feeding port, a second coal feeding port, and a third coal feeding port arranged sequentially from bottom to top, allowing pulverized coal to be added at different heights within the lower furnace body. Furthermore, the lower furnace body has an overall inverted conical design, with its cross-sectional area increasing from bottom to top. This allows for variations in the gas velocity in the fluidized bed; a smaller cross-sectional area results in a higher gas velocity, ensuring a high gas velocity at the bottom of the fluidized bed and achieving optimal fluidization, thus preventing slagging at the bottom of the gasifier. Additionally, the coordination of the air supply pipe and water spray pipe effectively reduces the bed temperature. Combined with the inverted conical design of the lower furnace body, this lowers the pressure and temperature near the central jet pipe while increasing the gas velocity in that area, further preventing slagging at the bottom of the gasifier.

Description

Technical fields:

[0001] This invention relates to the field of coal gasification technology, and more specifically to a dry pulverized coal gasification furnace. Background technology:

[0002] The main process of a high-pressure fluidized bed gasifier involves adding pulverized coal from the top of the moving bed into the gasifier, while the gasifying agent is introduced from the bottom. The fuel and gasifying agent flow counter-currently, and the ash residue is discharged from the bottom. The following problems exist during the operation of a high-pressure fluidized bed gasifier: 1. Traditional gasifiers have a cylindrical structure, with the gasifying agent entering from the bottom. A large amount of crude gas accumulates in the upper part of the gasifier, resulting in a higher volume of crude gas at the top than at the bottom. This leads to a lower gas velocity at the bottom of the fluidized bed, easily inducing slagging and causing difficulties in slagging removal. Frequent shutdowns for cleaning are necessary, resulting in significant economic losses for the enterprise. 2. In a fluidized bed gasifier, all oxygen enters through the central jet pipe in the central area at the bottom of the gasifier. Under high pressure, the gas velocity in the central jet pipe decreases significantly, while the oxygen concentration (the percentage of oxygen in the gasifying agent) remains constant. This creates an ultra-high temperature zone within the area covered by the central jet pipe. The high pressure, high temperature, and low gas velocity are also major causes of slagging in the gasifier. 3. The crude coal gas discharged from the gasifier is returned to the gasifier from below the central jet pipe after the fly ash is captured by the cyclone system. It cannot come into contact with the oxygen-containing gasifying agent, so the secondary gasification efficiency is low. Summary of the Invention:

[0003] The purpose of this invention is to provide a dry pulverized coal gasifier that can prevent slagging.

[0004] This invention is implemented by the following technical solution: a dry pulverized coal gasification furnace, comprising an upper furnace body, a fire-tube boiler, a lower furnace body, and a circular end cap connected sequentially from top to bottom. The upper furnace body is a conical furnace body with a gas outlet at its top. The lower furnace body is an inverted conical furnace body with a central jet pipe at the bottom center and a water spray nozzle at its upper part. A third coal feeding port, a second coal feeding port, and a first coal feeding port, arranged obliquely downwards, are sequentially arranged on the side wall of the lower furnace body below the water spray nozzle. A cyclone return port is also provided on the lower side wall of the lower furnace body.

[0005] The first coal feeding port and the cyclone return port are located above the nozzle of the central jet pipe. The first coal feeding port and the cyclone return port are within the spray range of the central jet pipe, and the angle between the first coal feeding port and the cyclone return port and the horizontal line is greater than 30°.

[0006] An air supply pipe and a cooling pipe are connected to the side of the circular head. An inverted conical air distribution plate is provided inside the circular head. The top edge of the air distribution plate is fixed to the bottom of the lower furnace body. A slag discharge pipe is connected to the bottom of the air distribution plate. The bottom of the slag discharge pipe extends to the bottom of the circular head. A slag discharge control valve is installed at the bottom of the slag discharge pipe.

[0007] Furthermore, a first pressure sensor is provided on the side of the circular head.

[0008] Furthermore, a second pressure sensor and a third pressure sensor are respectively installed on the bottom side wall and the top side wall of the lower furnace body.

[0009] Furthermore, a first temperature sensor is installed on the slag discharge pipe at the inlet end of the slag discharge control valve.

[0010] Furthermore, a second temperature sensor is provided on the side wall of the lower furnace body below the first coal feeding port.

[0011] Furthermore, a third temperature sensor is installed on the lower furnace sidewall between the water spray port and the second coal feeding port.

[0012] Furthermore, a water spray control valve is installed at the inlet end of the water spray nozzle, and a fourth temperature sensor, interlocked with the water spray control valve, is installed on the side wall of the lower furnace body above the water spray nozzle.

[0013] Furthermore, a fifth temperature sensor is provided on the side wall of the upper furnace body.

[0014] Furthermore, the cooling pipe is connected to the saturated steam branch pipe, a first regulating valve is installed on the saturated steam branch pipe, a sixth temperature sensor is installed on the side wall of the circular end cap, the detection probe of the sixth temperature sensor is located inside the air distribution plate, and the sixth temperature sensor is interlocked with the first regulating valve; a desuperheating water branch pipe is connected to the saturated steam branch pipe on the inlet side of the first regulating valve, a second regulating valve is installed on the desuperheating water branch pipe, and a seventh temperature sensor is installed on the saturated steam branch pipe between the desuperheating water branch pipe and the first regulating valve, and the seventh temperature sensor is interlocked with the second regulating valve.

[0015] Furthermore, a dredging pipe is connected to the slag discharge pipe at the inlet end of the slag discharge control valve.

[0016] The advantages of this invention are as follows: A first, second, and third coal feeding port are sequentially arranged from bottom to top on the lower furnace body, allowing pulverized coal to be added at different heights within the furnace body. The lower furnace body has an overall inverted conical design, with its cross-sectional area increasing from bottom to top. This allows for variations in the gas velocity within the fluidized bed; a smaller cross-sectional area results in a higher gas velocity, ensuring a high gas velocity at the bottom of the fluidized bed and achieving optimal fluidization, thus preventing slagging at the bottom of the gasifier. Furthermore, the combination of the air supply pipe and water spray pipe effectively reduces the bed temperature, and combined with the inverted conical design of the lower furnace body, increases the gas velocity in the vicinity, further preventing slagging at the bottom of the gasifier. The central jet pipe is positioned above the air distribution plate, causing the oxygen-containing gasifying agent to move upwards. The cyclone return port is located within the jet range of the central jet pipe, ensuring sufficient reaction between the cyclone return fly ash and the gasifying agent, thereby improving the efficiency of secondary gasification of returned pulverized coal. In addition, by setting fire tube boilers and water spray nozzles in the upper part of the gasifier, the temperature of the crude gas in the upper part of the gasifier can be controlled by cooling. This can significantly reduce the process design requirements of the subsequent equipment of the gasifier and reduce the difficulty of process processing. At the same time, the combination of cooling and capacity expansion can significantly reduce the gas velocity, which can effectively reduce the dust content in the crude gas. Attached image description:

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0018] Tag Name

[0019] 1-Upper furnace body, 2-Fire-tube boiler, 3-Lower furnace body, 4-Circular head, 5-Gas outlet, 6-Central jet pipe, 7-Water spray nozzle, 8-Third coal feed port, 9-Second coal feed port, 10-First coal feed port, 11-Cyclone return port, 12-Air supply pipe, 13-Air distribution plate, 14-Slag discharge pipe, 15-Slag discharge control valve, 16-First pressure sensor, 17-Second pressure sensor, 18-Third pressure sensor, 19-First temperature sensor, 20-Second temperature sensor, 21-Third temperature sensor, 22-Water spray control valve, 23-Fourth temperature sensor, 24-Fifth temperature sensor, 25-Drainage pipe, 26-Cooling pipe, 27-Saturated steam branch pipe, 28-First regulating valve, 29-Sixth temperature sensor, 30-Desuperheating water branch pipe, 31-Second regulating valve, 32-Seventh temperature sensor. Detailed implementation method:

[0020] In the description of this invention, it should be noted that terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] like Figure 1 As shown, a dry pulverized coal gasification furnace includes an upper furnace body 1, a fire-tube boiler 2, a lower furnace body 3, and a circular head 4 connected sequentially from top to bottom. The upper furnace body 1 is a conical furnace body with a gas outlet 5 at its top. The lower furnace body 3 is an inverted conical furnace body. The bottom end of the upper furnace body 1 is connected to the top end of the fire-tube boiler 2, the bottom end of the fire-tube boiler 2 is connected to the top end of the lower furnace body 3, and the bottom end of the lower furnace body 3 is connected to the top end of the circular head 4.

[0022] A central jet pipe 6 is installed at the bottom center of the lower furnace body 3. The central jet pipe 6 is the main inlet channel for the gasifying agent (oxygen + steam) of the gasifier, and all the oxygen required by the gasifier enters through this point. A water spray nozzle 7 is installed at the upper part of the lower furnace body 3. Water sprayed into the lower furnace body 3 through the water spray nozzle 7 can reduce the internal temperature of the lower furnace body 3. On the side wall of the lower furnace body 3 below the water spray nozzle 7, a third coal feeding port 8, a second coal feeding port 9, and a first coal feeding port 10 are arranged from top to bottom in a downward angle. A cyclone return port 11 is also provided on the lower side wall of the lower furnace body 3. The first coal feeding port 10 and the cyclone return port 11 are located at the same height on the side of the lower furnace body 3. The first coal feed port 10 and the cyclone return port 11 are located above the nozzle of the central jet pipe 6. They are within the spray range of the central jet pipe, and the angle between the first coal feed port 10 and the horizontal line is greater than 30° to ensure sufficient contact between the pulverized coal and the central jet. The first coal feed port 10 is the main coal feed port for the gasifier, accounting for 50% of the total coal input. The second coal feed port 9 is located in the middle of the bed, and the third coal feed port 8 is located in the upper part of the bed, with a maximum coal input of 10-30% for each, used to regulate the furnace temperature and gas composition. The cyclone return port 11 is located in the jet region above the central jet pipe 6, allowing the fly ash collected by the cyclone separator to fully contact and gasify with the central jet after returning to the gasifier, thus improving the secondary gasification conversion rate of the fly ash.

[0023] An air supply pipe 12 and a cooling pipe 26 are connected to the side of the circular head 4. The cooling pipe 26 is connected to a saturated steam branch pipe 27. A first regulating valve 28 is installed on the saturated steam branch pipe 27. A sixth temperature sensor 29 is installed on the side wall of the circular head 4. The detection probe of the sixth temperature sensor 29 is placed inside the air distribution plate 13. The sixth temperature sensor 29 is interlocked with the first regulating valve 28. The sixth temperature sensor 29 detects the temperature of the coal slag inside the air distribution plate 13 and adjusts the opening of the first regulating valve 28 according to the detected temperature to regulate the amount of saturated steam entering the circular head 4. Specifically, when the real-time temperature detected by the sixth temperature sensor 29 is higher than the set value, the opening of the first regulating valve 28 is increased to increase the amount of saturated steam supplied. A desuperheating water branch pipe 30 is connected to the saturated steam branch pipe 27 on the inlet side of the first regulating valve. A second regulating valve 31 is installed on the desuperheating water branch pipe 30. A seventh temperature sensor 32 is installed on the saturated steam branch pipe 27 between the desuperheating water branch pipe 30 and the first regulating valve. The seventh temperature sensor 32 is interlocked with the second regulating valve 31. The saturated steam temperature at the inlet side of the first regulating valve 28 is detected by the seventh temperature sensor 32. When the detected temperature exceeds the set value, the opening of the second regulating valve 31 is increased, increasing the flow rate of desuperheating water to regulate the saturated steam temperature.

[0024] An inverted conical air distribution plate 13 is installed inside the circular head 4. The top edge of the air distribution plate 13 is fixed to the bottom of the lower furnace body 3. The bottom end of the air distribution plate 13 is connected to a slag discharge pipe 14, which extends to the bottom of the circular head 4. A slag discharge control valve 15 is installed at the bottom end of the slag discharge pipe 14. The lower part of the central jet pipe 6 is the slag cooling zone. The cooling medium (steam / carbon dioxide) enters through small holes on the air distribution plate 13 to exchange heat with the high-temperature slag, thereby controlling the slag temperature. The cooled slag is discharged from the gasifier through the slag discharge pipe 14. The slag discharge speed can be adjusted by regulating the opening of the slag discharge control valve 15. A dredging pipe 25 is connected to the slag discharge pipe 14 at the inlet end of the slag discharge control valve 15. Steam and carbon dioxide are injected into the slag discharge pipe 14 from the dredging pipe 25, which serves two purposes: to dredge the channel and prevent blockage, and to control the slag temperature.

[0025] A first pressure sensor 16 is installed on the side of the circular head 4. The first pressure sensor 16 is used to detect the air chamber pressure between the air distribution plate 13 and the circular head 4. A second pressure sensor 17 and a third pressure sensor 18 are respectively installed on the bottom side wall and top side wall of the lower furnace body 3. The pressure difference detected by the second pressure sensor 17 and the third pressure sensor 18 is the fluidized bed pressure difference, which represents the fluidized bed height. The pressure difference is used to control the opening of the control valve of the slag discharge system. The higher the pressure difference, the larger the valve opening.

[0026] A first temperature sensor 19 is installed on the ash discharge pipe 14 at the inlet end of the ash discharge control valve 15; a second temperature sensor 20 is installed on the side wall of the lower furnace body 3 below the first coal feeding port 10; a third temperature sensor 21 is installed on the side wall of the lower furnace body 3 between the water spray port 7 and the second coal feeding port 9; a water spray control valve 22 is installed at the inlet end of the water spray port 7; a fourth temperature sensor 23, interlocked with the water spray control valve 22, is installed on the side wall of the lower furnace body 3 above the water spray port 7; and a fifth temperature sensor 24 is installed on the side wall of the upper furnace body 1. The upper part of the central jet pipe 6 can be divided into the bed material fluidization zone, the transition water spray temperature control zone, the dilute phase settling zone, and the cooling settling zone (fire-tube boiler 2). The first temperature sensor 19, the second temperature sensor 20, the third temperature sensor 21, the fourth temperature sensor 23, and the fifth temperature sensor 24 are used to monitor the fluidized bed temperature and provide a basis for fluidized bed operation. Specifically, the first temperature sensor 19 is used to detect the slag discharge temperature. When the slag discharge temperature exceeds the set maximum value, the flow rate of the cooling medium can be appropriately increased, and the pressure at the monitoring point of the first pressure sensor 16 can be increased to lower the slag temperature. The second temperature sensor 20 is used to detect the temperature at the bottom of the bed, and the third temperature sensor 21 is used to detect the temperature in the middle of the bed. The fourth temperature sensor 23 is used to detect the temperature of the dilute phase settling zone and controls the opening of the water spray control valve 22 based on the detected temperature to adjust the temperature of the dilute phase settling zone. The fifth temperature sensor 24 is used to detect the temperature of the crude gas.

[0027] The fluidization zone of the bed material is the main reaction area in the gasifier; the transition water spray temperature control zone cools down the gasifier by spraying water through the spray nozzle 7, controlling the temperature of the fourth temperature sensor 23 at the top of the gasifier to about 800℃; the dilute phase settling zone mainly functions to increase the cross-sectional area of ​​the furnace body and reduce the gas velocity of the crude gas after cooling by spraying water through the spray nozzle 7, thereby reducing its dust content; the cooling settling zone (fire tube boiler 2) mainly functions to further reduce the temperature of the crude gas to about 700℃ through the fire tube boiler 2, recovering high-temperature heat energy, and at the same time further reducing the gas velocity and dust content through cooling.

[0028] In this embodiment, by setting a fire-tube boiler 2 and a water spray nozzle 7 in the upper part of the gasifier, the temperature of the crude gas in the upper part of the gasifier is controlled by cooling. This can significantly reduce the process design requirements of the subsequent equipment of the gasifier and reduce the difficulty of process processing. At the same time, the combination of cooling and expansion can significantly reduce the gas velocity, which can effectively reduce the dust content in the crude gas.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dry powder coal gasifier characterized by, It includes upper furnace body, fire tube boiler, lower furnace body and round seal head connected in turn from top to bottom, the upper furnace body is a conical furnace body, the top of the upper furnace body is provided with a gas outlet; the lower furnace body is an inverted conical furnace body, a central jet pipe is arranged in the middle of the bottom end of the lower furnace body, a water injection port is arranged on the upper part of the lower furnace body; a third coal feeding port, a second coal feeding port and a first coal feeding port are arranged on the sidewall of the lower furnace body from top to bottom in turn below the water injection port, a cyclone back feeding port is further arranged on the sidewall of the lower furnace body; the first coal feeding port and the cyclone back feeding port are arranged above the nozzle of the central jet pipe, the first coal feeding port and the cyclone back feeding port are within the jet range of the central jet pipe, and the included angle between the first coal feeding port and the cyclone back feeding port and the horizontal line is greater than 30°; a blast pipe and a cooling pipe are communicated with the side of the round seal head, an inverted conical air distribution plate is arranged in the round seal head, the top end edge of the air distribution plate is fixed with the bottom end of the lower furnace body, a slag discharge pipe is communicated with the bottom end of the air distribution plate, the bottom end of the slag discharge pipe extends to the lower side of the round seal head, and a slag discharge control valve is arranged on the bottom end of the slag discharge pipe.

2. A dry powdered coal gasification furnace according to claim 1, wherein A first pressure sensor is arranged on the side of the round seal head.

3. A dry powdered coal gasification furnace according to claim 1, wherein A second pressure sensor and a third pressure sensor are respectively arranged on the bottom sidewall and the top sidewall of the lower furnace body.

4. A dry powdered coal gasification furnace according to claim 1, wherein A first temperature sensor is arranged on the slag discharge pipe at the inlet end of the slag discharge control valve.

5. A dry powdered coal gasification furnace according to claim 1, wherein A second temperature sensor is arranged on the sidewall of the lower furnace body below the first coal feeding port.

6. A dry powdered coal gasification furnace according to claim 1, wherein A third temperature sensor is arranged on the sidewall of the lower furnace body between the water injection port and the second coal feeding port.

7. A dry powdered coal gasification furnace according to claim 1, wherein A water injection control valve is arranged at the inlet end of the water injection port, and a fourth temperature sensor interlocked with the water injection control valve is arranged on the sidewall of the lower furnace body above the water injection port.

8. A dry powdered coal gasification furnace according to claim 1, wherein A fifth temperature sensor is arranged on the sidewall of the upper furnace body.

9. A dry powdered coal gasification furnace according to claim 1, wherein The cooling pipe is communicated with a saturated steam branch pipe, a first regulating valve is arranged on the saturated steam branch pipe, a sixth temperature sensor is arranged on the sidewall of the round seal head, the detection probe of the sixth temperature sensor is arranged on the inner side of the air distribution plate, the sixth temperature sensor is interlocked with the first regulating valve, a desuperheating water branch pipe is connected to the saturated steam branch pipe at the inlet side of the first regulating valve, a second regulating valve is arranged on the desuperheating water branch pipe, and a seventh temperature sensor is arranged on the saturated steam branch pipe between the desuperheating water branch pipe and the first regulating valve, the seventh temperature sensor is interlocked with the second regulating valve.

10. A dry powdered coal gasification furnace according to any one of claims 1 to 9, wherein A dredging pipe is communicated with the slag discharge pipe at the inlet end of the slag discharge control valve.

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