JP2015212584A - Exhaust heat recovery boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust heat recovery boiler for heating a water pipe provided in a boiler body part by flowing exhaust gas through the boiler body, in which an absorption amount of heat in the boiler body increases.SOLUTION: The exhaust heat recovery boiler comprises an inlet duct 3 and an outlet duct 4 provided at positions on the opposite sides of the boiler body 1, and is configured to heat the water pipe provided in the boiler body part by the exhaust gas. The exhaust heat recovery boiler is provided with: a lower guide plate 11 extending in a direction parallel to the water pipe, and having a surface for blocking the flow of exhaust gas in the lower portion of an exhaust gas flow path of the boiler body 1; and an upper guide plate 7 extending in the direction parallel to the water pipe, and having a surface for blocking the flow of exhaust gas in the upper portion of the exhaust gas flow path of the boiler body. The lower guide plate 11 and the upper guide plate 7 are arranged at intervals in the flow direction of exhaust gas so that a stream of the exhaust gas flowing through the boiler body 1 meanders.

Description

The present invention relates to an exhaust heat recovery boiler that recovers heat from high-temperature exhaust gas discharged from a gas engine or the like. More specifically, the present invention relates to an inlet duct on the side of the boiler body, and a boiler body on the opposite side of the inlet duct An outlet duct is provided at the side, heating is performed by introducing exhaust gas at a higher temperature than the inlet duct, and flowing the exhaust gas in a crossing direction with respect to the vertical water pipe provided in the boiler body, and the exhaust gas passes through the outlet duct. The present invention relates to an exhaust heat recovery boiler configured to exhaust.

In recent years, cogeneration has been carried out, in which exhaust gas emitted from a gas engine or the like is generated by combustion in a gas engine or the like, supplied to an exhaust heat recovery boiler, and heat is recovered from the exhaust gas by an exhaust heat recovery boiler. It has increased. In this case, the exhaust heat recovery boiler has an inlet duct on the side of the boiler body and an outlet duct on the side opposite to the inlet duct of the boiler body, as described in JP-A-2001-124301. The exhaust gas is allowed to flow from one end of the boiler body to the other end.

In the exhaust heat recovery boiler as shown in FIG. 4, an exhaust gas inlet 5 is provided in the upper part of the inlet duct 3, and the exhaust gas is introduced downward into the inlet duct 3. The boiler main body 1 is provided at a position adjacent to the inlet duct, and the inlet duct 3 and the boiler main body 4 are connected by opening the side surfaces so that the exhaust gas entering the inlet duct is discharged from the side surfaces of the inlet duct. Enter the heat transfer section. The flow of the exhaust gas flows downward in the inlet duct, and when it reaches the bottom of the inlet duct, the flow direction is changed by 90 degrees and flows toward the boiler body.

In the boiler body 1 part, an upper header is provided in the upper part and a lower header is provided in the lower part, and a number of vertical water pipes 8 are provided between the upper and lower headers. Exhaust gas in the boiler body part flows sideways through the part where the vertical water pipe 8 is provided. When the exhaust gas is brought into contact with the vertical water pipe, the exhaust gas heats the vertical water pipe and heats the can water in the water pipe to generate steam. An outlet duct 4 is provided on the side surface opposite to the inlet duct of the boiler body, and the exhaust gas that has passed through the boiler body portion enters the outlet duct. Since the exhaust gas outlet 6 is also provided in the upper part of the outlet duct 4, the exhaust gas that has entered the outlet duct changes its flow direction again in the outlet duct and flows upward from the outlet duct. .

In this case, it is ideal that the exhaust gas flowing through the boiler body part flows uniformly throughout the entire exhaust gas flow path in the boiler body. If there are few parts, the heat absorption efficiency will decrease. However, in the exhaust heat recovery boiler shown in FIG. 4, the exhaust gas that has entered the inlet duct 3 flows downward in the inlet duct, and much of the exhaust gas reaches the bottom surface of the inlet duct. Since the exhaust gas collides with the bottom surface of the inlet duct and changes the flow direction toward the boiler body, a lot of exhaust gas in the boiler body part flows in the lower part of the flow path, and the exhaust gas in the upper part of the boiler body part There was a dead space 9 where the flow decreased. If the dead space 9 with a small exhaust gas flow rate is formed in the boiler body, the amount of heat absorbed is reduced.

In such an exhaust heat recovery boiler, if the heat transfer area is increased, the amount of heat transferred from the exhaust gas to the water pipe increases. Therefore, the amount of heat absorption in the boiler body can be increased by increasing the number of installed water tubes and enlarging the boiler body. However, increasing the number of installed water pipes directly increases the cost of the apparatus, so the number of installed water pipes could not be increased in a dark manner.

JP 2001-124301 A

The problem to be solved by the present invention is:
An inlet duct is provided on the side of the boiler body, an outlet duct is provided on the side of the boiler body opposite to the inlet duct, hot exhaust gas is introduced from the inlet duct, and exhaust gas is allowed to flow through the boiler body to the boiler body. An exhaust heat recovery boiler that can increase the amount of heat absorbed in the boiler body in an exhaust heat recovery boiler that heats the water pipes provided and exhausts the exhaust gas used to heat the water pipes through the outlet duct. Is to provide.

The invention described in claim 1
An exhaust heat recovery boiler that recovers heat from high-temperature exhaust gas discharged from a gas engine or the like, and is provided with an inlet duct and an outlet duct at opposite positions of the boiler body, and introduced through the inlet duct In the exhaust heat recovery boiler that flows from the inlet duct to the outlet duct through the boiler body, the water pipe provided in the boiler body is heated by the exhaust gas.
A lower guide plate having a surface that extends in a direction parallel to the water pipe at the lower part of the exhaust gas flow path of the boiler body part and blocks the flow of exhaust gas,
An upper guide plate having a surface extending in a direction parallel to the water pipe and blocking the flow of exhaust gas is provided on the upper part of the exhaust gas flow path of the boiler body part,
The lower guide plate and the upper guide plate are installed with an interval in the flow direction of the exhaust gas so that the exhaust gas flow flowing through the boiler body portion is meandered.

According to a second aspect of the present invention, in the exhaust heat recovery boiler, the lower guide plate and / or the upper guide plate are partially provided with an opening hole, and a part of the exhaust gas flow is provided in the opening hole of the guide plate. It is characterized by flowing through the back of the guide plate.
According to a third aspect of the present invention, in the exhaust heat recovery boiler, the inlet duct has an exhaust gas inlet at an upper portion, and an outlet duct also has an exhaust gas outlet at an upper portion. A lower guide plate is provided closer to the inlet duct than the closer water pipe, and an upper guide plate is provided closer to the outlet duct than the water pipe closest to the outlet duct provided in the boiler body.
Invention of Claim 4 in the said waste heat recovery boiler,
A plurality of upper guide plates and lower guide plates are provided, and the upper guide plates and the lower guide plates are alternately arranged.
The invention according to claim 5 is the exhaust heat recovery boiler,
The lower guide plate and / or the upper guide plate are provided with an inclination so that the tip side approaches the direction of the outlet duct.
The invention according to claim 6 is the exhaust heat recovery boiler,
The lower guide plate and / or upper guide plate is characterized in that the guide plate installed on the downstream side of the exhaust gas flow of the boiler body has a longer length to the tip.

By carrying out the present invention, the exhaust gas flowing through the boiler main body part flows while meandering, and it becomes difficult to form a dead space for the exhaust gas in the boiler main body, so that the entire boiler main body can absorb heat. Therefore, the boiler body can absorb more heat from the exhaust gas.

Explanatory drawing which showed the exhaust gas flow of the waste heat recovery boiler which is implementing this invention 1 is a cross-sectional plan view taken along line AA in FIG. Explanatory drawing which showed the 2nd Example of the waste heat recovery boiler which is implementing this invention Explanatory drawing which showed the exhaust gas flow in the exhaust heat recovery boiler which has not implemented this invention

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing an exhaust gas flow of an exhaust heat recovery boiler embodying the present invention, and FIG. 2 is a plan view showing a cross section taken along the line AA of FIG. The boiler according to the embodiment is an exhaust heat recovery boiler that generates steam by recovering heat from high-temperature exhaust gas discharged from a gas engine or the like.
A combustion system including a combustion device such as a gas engine that generates power and an exhaust heat recovery boiler that uses exhaust gas discharged from the combustion device as a heat source has been increasing in recent years because energy can be effectively used. The configuration of the exhaust heat recovery boiler can be roughly divided into an inlet duct 3 for introducing high-temperature exhaust gas, a boiler body 1 for heating boiler water by the heat of the introduced exhaust gas, and exhaust gas passing through the boiler body is taken out from the boiler. It consists of an outlet duct 4.

The inlet duct 3 has an exhaust gas inlet 5 in the upper part, and is open to the boiler body 1 that is in contact with the side surface of the inlet duct 3.
The boiler body 1 is provided with an upper header at the upper part and a lower header at the lower part, and a number of vertical water pipes 8 are installed between the upper and lower headers.
On the outer surface of the vertical water pipe 8, the heat transfer area is expanded by providing a large number of heat absorbing fins.
Exhaust gas entering from the inlet duct 3 exchanges heat with the vertical water pipe 8 in the boiler body 1, and steam is generated by heating the can water in the vertical water pipe 8. Exhaust gas whose temperature has been lowered by heating the vertical water pipe 8 in the boiler body 1 is sent to the outlet duct 4 provided on the downstream side of the boiler body 1, and from the exhaust gas outlet 6 of the outlet duct 4 to the outside of the boiler. Discharge.

The outlet duct 4 is provided with a feed water preheating device 2 that performs heat exchange between the exhaust gas after the heat exchange in the boiler body and the boiler feed water.
The feed water preheating device 2 is composed of a large number of feed water preheating pipes extending horizontally in the exhaust gas passage. The feed water preheating pipe is installed so as to intersect the exhaust gas flow passing through the outlet duct 4, and the heat transfer area is expanded by providing a large number of heat absorbing fins on the outer surface of the feed water preheating pipe. . A large number of feed water preheating pipes are connected to form a long flow path. When boiler feed water is passed through the feed water preheating pipe, the temperature of the boiler feed water rises by absorbing the heat of the exhaust gas. Boiler feed water whose temperature has been raised by the feed water preheating device 2 is supplied to the boiler body 1.

A lower guide plate 11 is provided in the lower part at the boundary between the boiler body 1 and the inlet duct 3.
The lower guide plate 11 provided at the boundary portion with the inlet duct 3 is a plate extending in a direction parallel to the vertical water pipe 8, and is a large surface that intersects the flow of exhaust gas flowing from the inlet duct 3 to the outlet duct 4. To block the flow of exhaust gas.
The lower guide plate 11 is in contact with the bottom surface of the exhaust gas passage at the lower end, and the upper portion of the lower guide plate 11 is widely open from the ceiling surface of the exhaust gas passage. The lower guide plate 11 uses a punching plate, and a number of punching holes 10 are formed on the surface of the lower guide plate 11 that blocks the exhaust gas flow.

A portion of the boiler body 1 that is slightly inserted in the direction of the outlet duct 4 from the boundary with the inlet duct 3, in the figure, between the second row and the third row from the inlet duct side of the vertical water pipe 8, the upper guide plate is located at the upper portion. 7 is provided. Like the lower guide plate 11, the upper guide plate 7 is a plate extending in a direction parallel to the vertical water pipe 8, and has a large surface that intersects the flow of exhaust gas flowing from the inlet duct 3 to the outlet duct 4. The flow of exhaust gas is blocked.
The upper guide plate 7 is in contact with the ceiling surface of the exhaust gas passage at the upper end, and the lower portion of the upper guide plate 7 is widely open from the bottom surface of the exhaust gas passage.
The upper guide plate 7 also uses a punching plate, and a number of punching holes 10 are formed on the surface of the upper guide plate 7 that blocks the flow of exhaust gas.

In the embodiment, the lower guide plate 11 is provided between the fourth row and the fifth row of the vertical water pipe 8 that is further downstream of the exhaust gas flow, and the upper guide plate 7 is provided downstream of the most downstream vertical water pipe 8. Provided. The second lower guide plate 11 is a punching plate and has a punching hole 10, but only the upper guide plate 7 provided at the most downstream stage uses a flat plate without the punching hole 10. The plurality of guide plates provided have a length up to the tip toward the downstream side of the exhaust gas flow, and the downstream guide plate has a larger area for blocking the exhaust gas flow.

Exhaust gas flow will be described.
Since the inlet duct 3 is provided with the exhaust gas inlet 5 in the upper part, the exhaust gas that has entered from the exhaust gas inlet flows downward in the inlet duct 3. When the exhaust gas collides with the bottom of the inlet duct 3, the flow direction is changed to the direction of the boiler body 1 and flows toward the lower guide plate 11 provided at the boundary portion with the boiler body 1.

Since the lower guide plate 11 provided at the boundary with the inlet duct 3 is a punching plate having a large number of holes, when the exhaust gas collides with the lower guide plate 11, a part of the exhaust gas passes through the inlet duct 3. Although it enters the lower part of the boiler body through the punching hole from the lower part, the amount is limited. Since the lower guide plate 11 has an opening that is wide open upward, the exhaust gas flow that reaches the lower part of the inlet duct 3 is blocked by the lower guide plate 11 from entering the lower part of the boiler body 1. The gas passes through the upper part of the lower guide plate 11 and enters the upper part of the boiler body 1.
In this case, in the vertical water pipe 8 near the inlet duct 3, the exhaust gas that has passed over the upper side of the lower guide plate 11 flows in the upper part, and the exhaust gas that has passed through the punching hole 10 of the lower guide plate 11 flows in the lower part. Will flow.
Therefore, the dead space 9 in which the flow rate of the exhaust gas is reduced cannot be formed, and heat can be absorbed by the entire vertical water pipe 8.
Further, when the exhaust gas flow passes through the punching hole 10, a turbulent flow is generated, and the turbulent flow improves the heat transfer efficiency to the vertical water pipe 8.

However, even if the lower guide plate 11 has the punching hole 10, the exhaust gas amount sent to the back side of the lower guide plate 11 is a part of the whole and the exhaust gas amount passing through the opening above the lower guide plate 11 Less than Therefore, only by the amount of exhaust gas passing through the punching hole 10 of the lower guide plate 11, the amount of heat absorption at the lower portion of the vertical water pipe 8 on the back side of the lower guide plate 11 is reduced.
In this case, when the upper guide plate 7 is provided on the downstream side of the lower guide plate 11,
The exhaust gas flow that has entered the upper portion of the boiler body 1 from the inlet duct 3 flows toward the outlet duct 4, but the flow direction of the exhaust gas is also changed here by the upper guide plate 7. Since this upper guide plate 7 also has a punching hole 10, a part of the exhaust gas flow flows to the back side of the upper guide plate 7, but most of the exhaust gas blocked by the shielding surface of the upper guide plate 7 Since it flows toward the opening which is largely open below the guide plate 7, the flow is downward. Here, the exhaust gas flow which has become a downward flow is also sent to the lower part of the vertical water pipe 8 which is the back side of the lower guide plate 11, and the heat absorption amount in this part can be increased. Further, when exhaust gas is caused to flow in the vertical direction in the boiler body 1, turbulence of the exhaust gas flow can be promoted, and this also increases the amount of heat absorbed in the vertical water pipe 8. The exhaust gas flow that has reached the lower part of the boiler body flows in the direction of the outlet duct 4 through the lower part of the upper guide plate 7.

Further, since the second lower guide plate 11 is provided downstream thereof, the flow direction of the exhaust gas is similarly changed here. Since this lower guide plate 11 also has a punching hole 10, a part of the exhaust gas flow flows to the back side of the lower guide plate 11. In the case of the lower guide plate 11, since there is a large opening on the upper side, the exhaust gas flow blocked by the lower guide plate 11 becomes an upward flow here, and passes upward of the flow path toward the outlet duct 4. Flowing.
In this case as well, exhaust gas is supplied to the back side of the upper guide plate 7 by sending exhaust gas to the upper part of the flow path, so that a sufficient amount of exhaust gas is supplied to the back side of the upper guide plate 7. be able to.

Unlike the three guide plates so far, the upper guide plate 7 provided at the most downstream portion of the boiler body 1 does not have a punching hole 10.
Therefore, the exhaust gas flow that has reached the portion of the upper guide plate 7 does not flow to the back side of the upper guide plate 7 through the punching holes 10, but all flows below the upper guide plate 7. The reason why the punching hole 10 is provided by the three upstream guide plates is that a certain amount of exhaust gas is sent to the back side of the guide plate through the punching hole 10 so that the portion immediately behind the guide plate of the vertical water pipe 8 But to absorb heat. In the case of the outlet duct 4, since the feed water preheating device 2 is provided, it is the same as the three guide plates described above in that the exhaust gas needs to be sent to the back side of the upper guide plate 7. However, since the exhaust gas outlet 6 is provided in the upper part in the outlet duct 4, even if all of the exhaust gas is sent to the lower side of the outlet duct 4, the exhaust gas flows upward in the outlet duct 4, and the upper part. It also flows to the back side of the guide plate 7. Therefore, it is not necessary to provide the punching hole 10 in the upper guide plate 7. Then, by flowing all of the exhaust gas flow downward, the heat absorption amount in the vertical water pipe 8 at the most downstream side in the boiler body 1 can be increased.
Further, if the punching hole 10 is provided in the most downstream upper guide plate 7, the exhaust gas flow sent through the punching hole 10 immediately flows from the upper part of the feed water preheating device 2 to the exhaust gas outlet 6. become. In this case, the amount of heat absorbed by the feed water preheating device 2 is reduced. From this point of view, it is preferable that the punching hole 10 is not formed in the uppermost guide plate 7 on the most downstream side.

As described above, when the lower guide plate 11 and the upper guide plate 7 are alternately installed in the boiler body 1, the exhaust gas flow flowing in the boiler body 1 from the inlet duct 3 side toward the outlet duct 4 The flow is blocked by the guide plate 7 and the lower guide plate 11. And since the lower part of the flow path in the upper guide plate 7 and the upper part of the flow path in the lower guide plate 11 are largely open, the exhaust gas flow after the collision with the upper guide plate 7 or the lower guide plate 11 It flows toward a large vacant opening and flows below the upper guide plate 7 and above the lower guide plate 11.
In this way, when the meandering of the upward flow and the downward flow occurs in the exhaust gas flow, a sufficient amount of exhaust gas flows also on the back side of the guide plate. The amount of heat absorbed from can be increased.

As shown in FIG. 4, when there is no lower guide plate 11 and upper guide plate 7, exhaust gas that has entered the lower part of the boiler body 1 from the inlet duct 3 flows from the inlet duct 3 to the outlet duct 4. Flows in a straight line. In this case, the exhaust gas flow is deviated, and the amount of heat absorbed in the entire boiler body is small. By providing the upper guide plate 7 and the lower guide plate 11 and causing the exhaust gas flowing through the boiler main body portion to meander, the heat absorption efficiency in the boiler main body can be improved.

Further, since the exhaust gas flow flowing in the boiler body 1 flows while exchanging heat with the vertical water pipe 8, the temperature gradually decreases. When the temperature of the exhaust gas decreases, the volume of the exhaust gas also decreases, so that the exhaust gas flow becomes smaller in volume downstream. When the volume of the exhaust gas is reduced, the amount of heat transfer between the vertical water pipes 8 is reduced. As a result, the heat transfer amount to the vertical water pipe 8 by the exhaust gas can be increased.

FIG. 3 relates to a second embodiment of the present invention.
The difference from the embodiment shown in FIG. 1 is that the lower guide plate 11 and the upper guide plate 7 of FIG. 1 are installed almost vertically, whereas in the second embodiment, the lower guide plate 11 and the upper guide plate. 7 differs in that the front side is inclined in a direction approaching the outlet duct 4. Exhaust gas flow in the boiler body 1 portion largely flows from the inlet duct 3 to the outlet duct 4. When the lower guide plate 11 and the upper guide plate 7 are inclined from the vertical direction to the downstream side, when the exhaust gas flow collides with the lower guide plate 11 and the upper guide plate 7, the exhaust gas flow is changed to the lower guide plate 11 and the upper guide plate. Since it becomes difficult for the plate 7 to become a resistance, it can flow without causing much pressure loss.

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.

1 Boiler body
2 Water supply preheating device 3 Inlet duct 4 Outlet duct 5 Exhaust gas inlet 6 Exhaust gas outlet 7 Upper guide plate 8 Vertical water pipe 9 Dead space 10 Punching hole 11 Lower guide plate

Claims (6)

An exhaust heat recovery boiler that recovers heat from high-temperature exhaust gas discharged from a gas engine or the like, and is provided with an inlet duct and an outlet duct at opposite positions of the boiler body, and introduced through the inlet duct In the exhaust heat recovery boiler that flows from the inlet duct to the outlet duct through the boiler body, the water pipe provided in the boiler body is heated by the exhaust gas.
A lower guide plate having a surface that extends in a direction parallel to the water pipe at the lower part of the exhaust gas flow path of the boiler body part and blocks the flow of exhaust gas,
An upper guide plate having a surface extending in a direction parallel to the water pipe and blocking the flow of exhaust gas is provided on the upper part of the exhaust gas flow path of the boiler body part,
An exhaust heat recovery boiler characterized in that the lower guide plate and the upper guide plate are installed with a space in the exhaust gas flow direction to meander the exhaust gas flow flowing through the boiler body. 2. The exhaust heat recovery boiler according to claim 1, wherein the lower guide plate and / or the upper guide plate are partially provided with an opening hole, and a part of the exhaust gas flow passes through the opening hole of the guide plate. An exhaust heat recovery boiler characterized by flowing to the back of the boiler. In the exhaust heat recovery boiler according to claim 1 or 2,
The inlet duct has an exhaust gas inlet at the top, and the outlet duct has an exhaust gas outlet at the top.
A lower guide plate on the inlet duct side than the water pipe closest to the inlet duct provided in the boiler body,
An exhaust heat recovery boiler characterized in that an upper guide plate is provided on the outlet duct side of the water pipe closest to the outlet duct provided in the boiler body. In the exhaust heat recovery boiler according to any one of claims 1 to 3,
An exhaust heat recovery boiler, wherein a plurality of upper guide plates and lower guide plates are provided, and the upper guide plates and the lower guide plates are alternately arranged. In the exhaust heat recovery boiler according to any one of claims 1 to 4,
The exhaust heat recovery boiler according to claim 1, wherein the lower guide plate and / or the upper guide plate are provided with an inclination so that a distal end side thereof approaches a direction of the outlet duct. In the exhaust heat recovery boiler according to any one of claims 1 to 5,
In the exhaust heat recovery boiler, the lower guide plate and / or the upper guide plate has a longer length to the tip as the guide plate is installed on the exhaust gas flow downstream side of the boiler body.

Images