JP6433185B2 - Thermal equipment for preheating air - Google Patents

Description

  The present invention relates to a thermal apparatus that performs combustion, such as a boiler, and relates to a thermal apparatus that performs air preheating in which preheated combustion air is supplied to a combustion apparatus of the thermal apparatus.

As described in Japanese Patent Application Laid-Open No. 2014-89023, a boiler that preheats combustion air by performing heat exchange between the combustion air supplied to the boiler and the combustion gas discharged from the boiler is known. When the combustion air is preheated using the heat of the combustion gas discharged from the boiler, the flame temperature in the boiler can be raised, so that the efficiency of the boiler can be improved. The combustion air supplied to the boiler is pressurized by a blower and sent to the boiler through an air supply duct. A boiler has a structure in which a combustion chamber is provided in the center and a water pipe is arranged in an annular shape around the combustion chamber, and combustion is performed in a combustion chamber by a burner provided at the upper portion of the combustion chamber. The fuel is supplied from above the chamber into the combustion chamber. In such a boiler in which a burner is installed at the top of the combustion chamber, fuel is also injected from above the combustion chamber toward the combustion chamber. At this time, if there is a deviation in the flow of combustion air, uniform combustion cannot be performed, and the combustion state deteriorates. For this reason, a wind box for rectifying the combustion air is provided in front of the burner, and the combustion air rectified by the wind box is supplied to the burner.

When the combustion chamber is a cylindrical space, the burner and the wind box are also generally cylindrical. The cylindrical burner is designed to inject fuel near the center axis. A combustion cylinder is provided around the fuel injection portion, and combustion air is supplied through the combustion cylinder. If it is a burner that burns flames downward, a wind box is installed above the burner. The wind box is concentric with a cylindrical burner, and has a cylindrical outer cylinder larger than the outer diameter of the burner and a top plate that covers the upper surface of the outer cylinder. The inside of the wind box is connected so as to protrude from the base side of the combustion cylinder, and the inside of the wind box is divided into an inner space and an outer space by the combustion cylinder.

The outer cylinder of the wind box is connected to an air supply duct through which the combustion air from the blower that pushes in the combustion air is passed, and the combustion air sent through the air supply duct first enters the outer space of the wind box. . A space is provided between the upper end of the combustion cylinder and the windbox top plate to allow air to flow in. Combustion air that has entered the outer space passes over the upper side of the combustion cylinder and enters the inner space, and enters the combustion cylinder. Flows downward through the combustion section. The connection portion between the outer cylinder of the wind box and the air supply duct may be connected in a tangential direction to the outer cylinder or may be connected at a right angle to the outer cylinder. When the air supply duct is connected to the outer cylinder in the tangential direction, the combustion air flows along the inner peripheral surface of the outer cylinder, and enters the inner space while turning in the outer space. When the air supply duct is connected to the outer cylinder at a right angle, the inner space is on the extension line of the air supply duct, so the combustion air collides from the front with the outer peripheral surface of the combustion cylinder in the wind box, and the outer periphery of the combustion cylinder Enter the inner space while flowing along the surface. By rectifying the combustion air in the wind box, the combustibility in the combustion apparatus can be improved.

Further, in the boiler, the boiler water is heated by the high-temperature combustion gas generated by burning in the burner, and the combustion gas after heat exchange with the boiler water is discharged from the boiler. Since the combustion gas discharged at this time has a heat of about several hundred degrees Celsius, heat is recovered from the discharged combustion gas. If the boiler feed water or combustion air is preheated by the combustion gas, the efficiency of the boiler can be improved. Japanese Unexamined Patent Application Publication No. 2014-89023 includes an air heater that exchanges heat between combustion air and combustion gas, and the combustion air is preheated by the exhausted combustion gas.

When the combustion air is preheated by the air heater, the combustion air entering the wind box becomes high temperature. Then, the outer temperature of the wind box rises, and heat is released from the wind box. Around the wind box, control devices and measuring devices necessary for the operation of the boiler are arranged, and when the amount of heat released from the wind box becomes high, these devices may be adversely affected. Therefore, it is necessary to prevent heat from being released by, for example, winding a heat insulating material around the wind box. The windbox has a burner, but the burner must be removable for maintenance. For this reason, it is necessary to make the structure in which the burner can be removed even when the heat insulating material is wound around the wind box, and the structure is complicated.

JP 2014-89023 A

  The problem to be solved by the present invention is a thermal device that preheats combustion air, and the preheated combustion air is supplied to a burner via a wind box. It is to reduce the heat radiation from the windbox.

The invention according to claim 1 is a thermal apparatus having a combustion device such as a boiler, wherein the combustion air supplied to the combustion device is rectified by a wind box, and the air preheats the combustion air in the middle In a thermal apparatus that performs air preheating in which a preheated combustion air is supplied to a combustion device by connecting a supply duct provided with a preheating device to the outer portion of the windbox, the outer portion of the windbox Provides a double wall consisting of the outer wall of the windbox and the inner wall of the windbox, the inside of the inner wall of the windbox is the rectifying space, and the space between the outer wall of the windbox and the inner wall of the windbox is the endothermic space, The heat absorption space is connected to the air supply duct or the rectification space at the most downstream part, and the combustion air passing through the air preheating device is adjusted to the windbox. An air supply duct that supplies air to the space, and a bypass air supply pipe that branches from the upstream side of the air preheating device of the air supply duct and supplies combustion air to the heat absorption space of the wind box without passing through the air preheating device. Combustion air supplied through the air supply duct is supplied directly to the rectifying space provided inside the inner wall of the wind box, and combustion air supplied through the bypass air supply pipe is provided outside the inner wall of the wind box. It is characterized in that it enters the rectifying space after passing through the endothermic space.

  According to a second aspect of the present invention, in the combustion apparatus that performs the air preheating, the heat absorption space is installed so as to surround the rectification space, and is connected to the supply duct or the rectification space at the most downstream portion of the heat absorption space. The combustion air that has flowed through the heat absorption space is merged with the combustion air from the air supply duct at the end of the heat absorption space.

In this case, since the preheated combustion air does not contact the outer wall of the windbox, the outermost surface of the windbox is not heated by the combustion air. Since the preheated combustion air comes into contact with the inner wall of the wind box, the temperature of the inner wall rises, and heat is released from the inner wall to the surroundings. However, combustion air that has not been preheated flows on the outer peripheral side of the inner wall, and the heat released from the inner wall is absorbed by the combustion air that has not been preheated. Therefore, the temperature rise of the outer wall forming the outline of the wind box is reduced, and the amount of heat released from the outline of the wind box to the surroundings is reduced.

By carrying out the present invention, the amount of heat released from the outline of the wind box to the surroundings is reduced, so that it is possible to reduce the influence of heat on the control devices and measuring devices installed around the wind box. . Reduction in efficiency can be reduced by reducing the amount of heat released from the windbox and increasing the amount of heat supplied to the combustion section. Since there is no need to install a heat insulating material on the wind box, the wind box can be easily disassembled and the burner can be easily taken out.

Flow diagram of boiler implementing the present invention Sectional plan view of the wind box portion in the first embodiment Partial cross-sectional perspective view of the wind box portion in the first embodiment Sectional plan view of the windbox portion in the second embodiment Sectional plan view of the wind box portion in the third embodiment

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flow diagram of a boiler embodying the present invention, FIG. 2 is a sectional plan view of a wind box portion in the first embodiment, and FIG. 3 is a partial sectional perspective view of a wind box portion in the first embodiment. 4 is a cross-sectional plan view of the wind box portion in the second embodiment, and FIG. 5 is a cross-sectional plan view of the wind box portion in the third embodiment.

A boiler 11 shown in FIG. 1 has a combustion chamber in the center, and has a configuration in which the periphery of the combustion chamber is surrounded by a heat transfer tube. In the boiler 11, the heat use device 14 is connected to the heat use device 14 by a heat medium circulation pipe 15, and heat supply to the heat use device 14 is performed by circulating the heat medium between the heat use device 14 and the boiler 11. The heating medium boiler that performs A combustion device is installed in the upper part of the combustion chamber, and the combustion device burns the flame downward toward the combustion chamber. The heat medium is heated by combustion, the heated heat medium is supplied to the heat using device 14, the heat is used in the heat using device 14, and the heat medium whose temperature has decreased is returned to the boiler 11 to be heated again.

The combustion apparatus is provided with a cylindrical wind box 1 and a fuel injection portion at a central axis portion of the wind box 1. In the wind box 1, there is provided a combustion cylinder 3 that is concentric with the wind box 1 and is installed so as to penetrate the bottom surface of the wind box 1. The upper end of the combustion cylinder 3 is positioned lower than the ceiling surface of the wind box 1, and an inlet passage for allowing combustion air to enter the combustion cylinder 3 is formed between the upper end of the combustion cylinder 3 and the wind box ceiling surface. ing. The lower end of the combustion cylinder 3 extends below the bottom surface of the wind box 1 and sends combustion air through the combustion cylinder 3 to the tip of the combustion cylinder 3. A baffle plate for dispersing and supplying combustion air flowing in the combustion cylinder 3 to the combustion section is provided at the tip of the combustion cylinder 3. Combustion air is ejected to the combustion section. A fuel gas pipe 5 is provided in the central axis portion of the combustion cylinder 3, a fuel injection nozzle is installed at the tip of the fuel gas pipe ahead of the baffle plate, the fuel gas injected from the fuel injection nozzle, Combustion air flowing around is mixed to perform combustion.

The outer portion of the wind box 1 is provided with a double wall composed of an outer wall 8 of the wind box and an inner wall 9 of the wind box, and the heat absorbing space 6 and the inner side of the inner wall 9 of the wind box are provided between the double walls. Is the rectifying space 4. The endothermic space 6 is a thin annular space, and surrounds the periphery of the rectifying space 4. In the portion partitioned by the wind box inner wall 9 between the rectifying space 4, the endothermic space 6 and the rectifying space 4 are separated. Combustion air does not flow between them.

An air supply duct 2 that supplies combustion air from a blower 10 is connected to the wind box 1. In the first embodiment, the air supply duct 2 is connected in the tangential direction of the wind box. An air heater 7 is provided in the middle of the air supply duct 2. The air heater 7 is between the exhaust gas discharged from the boiler 11 through the exhaust duct 13 after heating the heat medium in the boiler 11 and the combustion air being sent from the blower 10 to the combustion device through the air supply duct 2. Heat exchange is performed, and the temperature of the combustion air rises by passing through the air heater 7.
The air supply duct 2 is connected to the inside of the inner wall 9 of the wind box, that is, to the rectifying space 4. Combustion air that has entered the rectifying space 4 enters the inside of the combustion cylinder 3 while swirling in the space between the windbox inner wall 9 and the combustion cylinder 3.

Combustion air is also supplied to the endothermic space 6 side of the windbox 1, and a bypass air supply pipe 12 is connected to the endothermic space 6. The bypass air supply pipe 12 branches from the upstream side of the air heater 7 of the air supply duct 2 and is connected to the wind box 1 without passing through the air heater 7. Therefore, the bypass air supply pipe 12 enters the heat absorption space 6 through the bypass air supply pipe 12. The temperature of the combustion air is lower than the preheated combustion air temperature that enters the rectifying space 4 after passing through the air heater 7. In the first embodiment, the endothermic space 6 is connected to the air supply duct 2 at the most downstream part after making one round of the circumference of the rectifying space 4, and the combustion air sent through the bypass air supply pipe is After making one round of the endothermic space 6, it merges with the combustion air sent through the air supply duct 2.

When the wind box 1 has such a structure, the combustion air that has been preheated by the air heater 7 and rises in temperature enters the combustion cylinder 3 while swirling in the rectifying space 4. When the preheated combustion air is swirling in the rectifying space 4, a part of the heat held by the preheated combustion air is transferred to the windbox inner wall 9 and the temperature of the windbox inner wall 9 is increased. In the inner wall 9 of the wind box where the temperature has risen, heat is released to the endothermic space 6 which is the surface opposite to the rectifying space 4. Flowing non-preheated combustion air is taken in. For this reason, even when high-temperature combustion air is supplied to the wind box, the amount of heat released around the wind box can be reduced. Further, since the combustion air flowing in the heat absorption space 6 enters the rectifying space 4 after recovering the heat released from the inner wall 9 of the windbox, this heat can also be used effectively.

It is also conceivable that the temperature of the windbox outer wall 8 rises due to an increase in the temperature of the combustion air flowing in the endothermic space 6. However, the amount of increase in the combustion air temperature in the endothermic space 6 is significantly lower than the amount of increase in the combustion air temperature in the air heater 7. Therefore, the amount of temperature rise at the windbox outer wall 8 is small, and the amount of heat released from the windbox outer wall 8 is small. Since the heat radiation from the windbox is reduced, the devices around the windbox are not affected by heat.

In the second embodiment, the air supply duct 2 is connected so that the vertical center axis of the windbox 1 and the extension line of the horizontal central axis of the air supply duct intersect. Also in this case, the outer wall portion of the wind box 1 is provided with a double wall body composed of the wind box outer wall 8 and the wind box inner wall wall 9, and the heat absorption space 6 between the double wall and the inner side is provided. A further inside of the inner wall 9 of the wind box that is a wall is a rectifying space 4.

  An air supply duct 2 that supplies combustion air from the blower 10 and a bypass air supply pipe 12 branched from the air supply duct 2 are connected to the wind box 1. The air supply duct 2 is connected to the rectifying space 4, and the combustion air that has entered the wind box 1 from the air supply duct 2 collides with the combustion cylinder 3 from the front and follows the outer surface of the combustion cylinder 3. Then, it enters the inside of the combustion cylinder 3 while flowing separately on the left and right. A bypass air supply pipe 12 is connected to the heat absorption space 6. The heat absorption space 6 makes a round around the rectifying space 4 and then merges with the combustion air sent through the air supply duct 2 in the vicinity of the boundary between the air supply duct 2 and the rectification space 4. Therefore, the combustion air sent through the bypass air supply pipe 12 finally joins with the combustion air supplied through the air supply duct 2.

Again, an air heater 7 is provided in the middle of the air supply duct 2, and the temperature of the combustion air rises by passing the air heater 7. Combustion air that has entered the wind box 1 from the air supply duct 2 flows through the rectifying space 4 and enters the inside of the combustion cylinder 3 from the periphery of the combustion cylinder 3. At this time, since the combustion air flowing in the rectifying space 4 has an increased temperature, the combustion air heats the inner wall 9 of the wind box.

When the temperature of the inner side wall 9 of the wind box rises, heat is released from the inner side wall 9 of the wind box to the heat absorbing space 6, but combustion air that has not been preheated flows through the heat absorbing space 6. The heat from the inner wall 9 is recovered by the combustion air flowing in the endothermic space 6.
By doing in this way, the amount of heat released from the wind box 1 to the periphery thereof can be reduced, and the influence of heat on the control device and the measuring device installed around the wind box 1 can be reduced.

The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention. For example, in the third embodiment shown in FIG. 5, the endothermic space 6 is changed from the second embodiment. In this embodiment, the final end of the heat absorption space is opposite to the bypass air supply pipe 12 connecting portion with the combustion cylinder 3 interposed therebetween. In this case, the combustion air that has entered the heat absorbing space 6 from the bypass air supply pipe 12 proceeds separately on the upper side and the lower side in the figure. The windbox inner wall 9 is cut out at the end portion of the endothermic space 6 so that combustion air flowing in the endothermic space 6 enters the rectifying space 4 from the end of the endothermic space. Even with such a configuration, the invention for reducing the amount of heat released from the windbox can be implemented.

1 Windbox
2 Air supply duct
3 Combustion cylinder
4 Rectification space
5 Fuel gas pipe
6 Endothermic space
7 Air heater 8 Wind box outer wall 9 Wind box inner wall
DESCRIPTION OF SYMBOLS 10 Blower 11 Boiler 12 Bypass air supply pipe 13 Exhaust duct 14 Heat use apparatus 15 Heat medium circulation piping

Claims (2)

It is a heat device with a combustion device such as a boiler, and the combustion air supplied to the combustion device is rectified by a wind box, and an air supply duct provided with an air preheating device for preheating the combustion air is provided on the way. By connecting to the outer part of the wind box, in the thermal equipment that performs the air pre-heating to supply the pre-heated combustion air to the combustion device,
The outer portion of the wind box is provided with an inner / outer double wall consisting of an outer wall of the wind box and an inner wall of the wind box, and the inner side of the inner wall of the wind box is sandwiched between the rectifying space and the outer wall of the wind box and the inner wall of the wind box. The endothermic space is the endothermic space, and the endothermic space is connected to the air supply duct or the rectifying space at the most downstream portion ,
An air supply duct for supplying combustion air that has passed through an air preheating device to the rectifying space of the wind box;
A bypass air supply pipe that branches from the upstream side of the air preheating device of the air supply duct and supplies combustion air to the heat absorption space of the wind box without passing through the air preheating device is provided.
Combustion air supplied through the air supply duct is supplied directly to the rectifying space provided inside the inner wall of the wind box,
Combustion air supplied through the bypass air supply tube, the thermal device that performs air preheater, characterized in that it is to enter into the rectifying space after passing through the endothermic space provided outside the wind box inner wall. The thermal apparatus for preheating air according to claim 1, wherein the heat absorption space is installed so as to surround the rectification space, and is connected to the air supply duct or the rectification space at the most downstream portion of the heat absorption space. A combustion apparatus for preheating air, characterized in that combustion air that has flowed through the space joins combustion air from an air supply duct at the end of the heat absorption space.

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