JP2020180719A - Heat pipe type exhaust heat recovery facility and hot stove facility equipped therewith - Google Patents

Abstract

To provide a heat pipe type exhaust heat recovery facility preventing occurrence of acid dew-point corrosion by raising the minimum temperature in an exhaust gas flow passage and uniformizing temperature distribution, and allowing effective use of exhaust gas heat by suppressing a heat transfer amount from the exhaust gas to gas to be heated, and a hot stove equipped with the exhaust heat recovery facility.SOLUTION: An exhaust heat recovery facility 1 has a first casing part 7 having a gas to be heated flow-in port 3 and a flow-out port 5, a second casing part 13 placed directly under the first casing part 7 and having an exhaust gas flow-in port 9 and a flow-out port 11, and a plurality of heat pipes 15 with one ends arranged in the first casing part 7 and the other ends arranged in the second casing part 13. The facility has a bypass flow passage 19 bypassing a first region out of the first region being a part inside the second casing part 13 and a second region downstream in the exhaust gas flow direction from the first region arranged with the heat pipes 15. A part of the exhaust gas is introduced to the second region without passing through the first region.SELECTED DRAWING: Figure 1

Description

The present invention relates to a heat pipe type exhaust heat recovery facility and a hot air furnace facility provided with the heat pipe type exhaust heat recovery facility.

There is an exhaust heat recovery facility that recovers exhaust heat from the exhaust gas of a hot air furnace for supplying high-temperature gas to a blast furnace and preheats the air for burning fuel in the hot air furnace. In this exhaust heat recovery facility, when the exhaust gas contains SOx components, when the exhaust gas outlet temperature of the heat exchanger falls below a certain temperature (acid dew point), the moisture in the exhaust gas condenses to generate sulfuric acid, and the acid dew point. Corrosion may occur. In order to prevent this, it is necessary to maintain the outlet temperature of the exhaust gas above a certain temperature.

In order to prevent the occurrence of such acid dew point corrosion, in Patent Document 1, a bypass pipe is provided in the heated gas system of the heat exchanger, and when there is a concern about a temperature drop in the heat exchanger, the bypass pipe is provided. By opening the bypass valve (flow control valve) installed in the heat exchanger, the amount of heated gas flowing through the heat exchanger is reduced to reduce the amount of heat recovery, thereby raising the exhaust gas outlet temperature of the heat exchanger. ing.

Japanese Unexamined Patent Publication No. 62-17108

In the method of Patent Document 1, by reducing the amount of heat recovered by the heated gas, the average temperature of the entire exhaust gas outlet of the heat exchanger can be raised to raise the temperature on the outlet side of the heat exchanger, but bypassing The heated gas flowing through the tube is not heated, and the amount of preheating of the heated gas is reduced.

The present invention has been made to solve such a problem, and effectively utilizes the heat of the exhaust gas by preventing the occurrence of acid dew point corrosion and suppressing the decrease in the amount of heat transfer from the exhaust gas to the heated gas. It is an object of the present invention to provide a heat pipe type exhaust heat recovery facility and a hot air furnace facility equipped with the heat pipe type exhaust heat recovery facility.

(1) The heat pipe type exhaust heat recovery facility according to the present invention preheats the heated gas to be preheated by the heat of high-temperature exhaust gas that can generate sulfuric acid when the temperature drops below the acid dew point.
A first casing portion having a heated gas inlet and a heated gas outlet,
A second casing portion that is arranged directly below the first casing portion and has an exhaust gas inlet and an exhaust gas outlet.
A plurality of heat pipes in which one end in the longitudinal direction is arranged in the first casing portion and the other end in the longitudinal direction is arranged in the second casing portion.
A first region in the second casing portion, which is a part of a region in which the plurality of heat pipes are arranged, and a part of the region in which the plurality of heat pipes are arranged, which is more than the first region. Of the second region located on the downstream side in the flow direction of the exhaust gas, the second region is provided with a bypass flow path that bypasses the first region, and a part of the exhaust gas does not pass through the first region. It is characterized in that it is configured to be introduced in.

(2) Further, in the above (1), the bypass flow path is configured to guide the partial exhaust gas above the center of the second casing portion in the vertical direction. It is a feature.

(3) Further, in the above-mentioned (1) or (2), the bypass flow path is a first opening provided on the upstream side in the flow direction of the exhaust gas from the first region. It has a second opening provided on the downstream side of the first region in the flow direction of the exhaust gas.
The bypass flow path is formed so as to guide the part of the exhaust gas flowing in from the first opening to the second region through the second opening without passing through the first region. It is a feature.

(4) Further, in the above-described item (3), the center of the second opening in the vertical direction is located above the center of the second casing in the vertical direction. is there.

(5) Further, in the one described in (3) or (4) above, the flow path wall forming the bypass flow path has a guide portion for guiding a part of the exhaust gas upward.
The guide portion is characterized in that the position of the end portion on the upstream side is lower than the position of the end portion on the downstream side.

(6) Further, in any one of the above (3) to (5), the second opening is provided with an opening degree adjusting device configured to be able to adjust the opening degree of the second opening. is there.

(7) The hot blast furnace equipment according to the present invention includes a hot blast furnace for supplying high temperature gas to the blast furnace.
The heat pipe type exhaust heat recovery facility according to any one of (1) to (6) above is provided.
One of the air and the fuel for burning the fuel in the hot air furnace by the heat of the exhaust gas generated by the heat pipe type exhaust heat recovery facility burning the fuel in the hot air furnace. Is configured to be preheated as the heated gas.

(8) In addition, a hot air furnace for supplying high temperature gas to the blast furnace and
The heat pipe type exhaust heat recovery facility according to any one of (1) to (6) above, wherein the fuel is generated in the hot air furnace by the heat of exhaust gas generated by burning the fuel in the hot air furnace. A first exhaust heat recovery facility configured to preheat the air for burning the fuel as the heated gas.
The heat pipe type exhaust heat recovery facility according to any one of (1) to (6) above, in the hot air furnace, due to the heat of the exhaust gas generated by burning the fuel in the hot air furnace. It is characterized by including a second exhaust heat recovery facility configured to preheat the fuel gas, which is the fuel to be burned, as the heated gas.

In the present invention, the first region which is a part of the region where the plurality of heat pipes are arranged in the second casing portion and the first region which is a part of the region where the plurality of heat pipes are arranged and are said. Of the second region located on the downstream side in the flow direction of the exhaust gas, a bypass flow path that bypasses the first region is provided, and a part of the exhaust gas is introduced into the second region without passing through the first region. It is configured to be. As a result, it is possible to raise the temperature in the region where the exhaust gas temperature tends to be low in the second casing, prevent the occurrence of acid dew point corrosion, and reduce the amount of heat transfer from the exhaust gas to the heated gas. It is possible to provide a heat pipe type exhaust heat recovery facility that can suppress and effectively utilize the heat of exhaust gas.

It is a perspective view of the exhaust heat recovery equipment which concerns on Embodiment 1 of this invention. It is explanatory drawing of the internal structure of the exhaust heat recovery facility shown in FIG. FIG. 2 is a cross-sectional view taken along the line AA of FIG. FIG. 2 is a cross-sectional view taken along the line BB of FIG. It is explanatory drawing of the hot air furnace equipment which concerns on Embodiment 2 of this invention. It is explanatory drawing of the hot air furnace equipment which concerns on Embodiment 3 of this invention.

[Embodiment 1]
The exhaust heat recovery facility 1 according to the present embodiment preheats the heated gas to be preheated by the heat of the high-temperature exhaust gas that generates sulfuric acid when the temperature drops below the acid dew point, and FIGS. As shown in the above, a first casing portion 7 having a heated gas inlet 3 and a heated gas outlet 5 and a first casing portion 7 arranged directly under the first casing portion 7 and having an exhaust gas inlet 9 and an exhaust gas outlet 11. Two casings 13 and a plurality of heat pipes 15 having one end in the longitudinal direction arranged in the first casing 7 and the other end in the longitudinal direction in the second casing 13. I have.
Further, the first region (see FIG. 2) which is a part of the region where the plurality of heat pipes 15 are arranged in the second casing portion 13 and a part of the region where the plurality of heat pipes 15 are arranged. Of the second region (see FIG. 2) located downstream of the first region in the flow direction of the exhaust gas, a bypass flow path 19 that bypasses the first region is provided, and a part of the exhaust gas is the first. It is configured to be introduced into the second region without passing through the region.
Hereinafter, each configuration will be described in detail. In the following description, the upstream side and the downstream side of the second casing portion 13 mean the upstream side and the downstream side in the flow direction of the exhaust gas flowing inside.

<First casing part>
The first casing portion 7 has a heated gas inflow port 3 into which the heated gas flows into one end side, and a heated gas outflow port 5 from which the heated heated gas flows out on the other end side. ..
Examples of the gas to be heated include air for burning the fuel gas in the hot air furnace and fuel gas for burning in the hot air furnace.
In the present embodiment, as shown in FIGS. 1 to 4, the first casing portion 7 is directed toward the first main body portion 21 having a rectangular parallelepiped outer shape and the heated gas inflow port 3 in the first main body portion 21. A first inflow side diameter reduction portion 23 that is continuously reduced in diameter and a first outflow side diameter reduction portion 25 that is continuously reduced in diameter toward the heated gas outlet 5 in the first main body portion 21 are provided. Has been done.

<Second casing part>
The second casing portion 13 is arranged directly under the first casing portion 7 via a pipe plate 27 for fixing the heat pipe 15, and has an exhaust gas inflow port 9 into which exhaust gas as a heating gas flows into one end side. It has an exhaust gas outlet 11 on the end side through which exhaust gas flows out.
Since the exhaust gas flowing through the second casing portion 13 and the heated gas flowing through the first casing portion 7 have opposite flow directions, the exhaust gas flowing above the exhaust gas inlet 9 in the second casing portion 13 is located above. The heated gas outlet 5 of the 1 casing portion 7 is arranged, and the heated gas outlet 3 of the first casing portion 7 is arranged above the exhaust gas outlet 11 of the second casing portion 13.

When the heated gas is air for burning the fuel gas in the hot air furnace or fuel gas to be burned in the hot air furnace, examples of the exhaust gas include exhaust gas discharged from the hot air furnace.
In the present embodiment, the diameter of the second casing is reduced toward the second main body 29 having a rectangular parallelepiped outer shape and the exhaust gas inlet 9 in the second main body 29, similarly to the first casing 7. It is configured to include a continuous second inflow side reduced diameter portion 31 and a second outflow side reduced diameter portion 33 that is continuously reduced in diameter toward the exhaust gas outlet 11 in the second main body portion 29.

<Heat pipe>
The heat pipe 15 penetrates the pipe plate 27 provided at the boundary between the first casing portion 7 and the second casing portion 13, and one end (heat dissipation portion) is arranged in the first casing portion 7. The other end (heat receiving portion) is arranged in the second casing portion 13 and fixed to the pipe plate 27.

The heat pipes 15 form a group of heat pipes having a predetermined number of pipes, and the heat pipe groups are arranged in the first casing portion 7 and the second casing portion 13 along the gas flow. The rectangles shown by diagonal lines in FIGS. 2 to 4 indicate that a large number of heat pipes 15 are aggregated to form a heat pipe group.
The first casing portion 7, the second casing portion 13, and the heat pipe 15 form a so-called heat pipe type heat exchanger.
In the present embodiment, the first region in the second casing portion 13 is a region including the most upstream heat pipe among the plurality of heat pipes, and the exhaust gas introduced into the second region through the bypass flow path 19 will eventually be discharged. Although it is not in contact with the heat pipe of No. 1, the first region may be set as any region as long as it is a region on the upstream side of the second region.

<Bypass flow path>
The bypass flow path 19 is a flow path that bypasses the first region, which is a part of the region in which the plurality of heat pipes 15 are arranged in the second casing portion 13.
More specifically, the bypass flow path 19 is introduced so that a part of the exhaust gas is introduced into the second region located on the downstream side in the flow direction of the exhaust gas from the first region without passing through the first region. It is for doing.

As shown in FIGS. 1 and 4, the bypass flow path 19 is provided from the duct 37 provided on the outside of both side walls of the second casing portion 13 to form the flow path wall, and from the first region inside the duct 37. The first opening 39 for introducing the exhaust gas into the duct 37 provided on the upstream side in the flow direction of the exhaust gas, and the exhaust gas in the duct 37 provided on the downstream side in the flow direction of the exhaust gas from the first region. Is configured by a second opening 41 for introducing the heat pipe 15 side.
The bypass flow path 19 as described above can guide a part of the exhaust gas flowing in from the first opening 39 to the second region through the second opening 41 without passing through the first region.

The reason why the bypass flow path 19 is provided is as follows.
When there is no bypass flow path 19, all the exhaust gas flows from the exhaust gas inlet 9 into the second casing portion 13, passes through the first region in the second casing portion 13, reaches the second region, and reaches the exhaust gas outlet. It flows out from 11. At this time, the temperature of the exhaust gas is highest when it flows in from the exhaust gas inlet 9, is cooled by heat exchange with the heat pipe 15 in the second casing portion 13, and is lowest when it flows out from the exhaust gas outlet 11. ing.
As mentioned above, as a major problem in heat exchangers, when the exhaust gas temperature falls below a certain temperature (acid dew point), acid dew point corrosion due to the SOx component contained in the exhaust gas may occur, and in order to prevent this, , It is necessary to maintain the exhaust gas temperature above a certain temperature. The acid dew point varies depending on various conditions such as gas components, but in most cases, it is a value of about one hundred and several tens of degrees.
Therefore, in the present embodiment, the exhaust gas having a high temperature that does not pass through the first region is introduced into the second region so that the exhaust gas temperature in the second region is maintained above a certain level.
Since the heat of the exhaust gas flowing into the second region is recovered by the heat pipe arranged in this region, the heat of the exhaust gas is compared with the conventional method of bypassing the heated gas to prevent acid dew point corrosion. Can be used more effectively.

In the present embodiment, the second opening 41 is provided at two locations on each side wall of the second casing portion 13, and each second opening 41 is provided with an opening / closing door 43 that functions as an opening adjusting device. It is provided so that the opening degree of the second opening 41 can be adjusted.
By providing the opening degree adjusting device in this way, for example, when it is detected that the temperature on the exhaust gas outlet side of the second casing portion 13 is low, the amount of exhaust gas introduced from the second opening 41 into the second region is increased. You can make adjustments such as. Further, it is also possible to install a thermometer for measuring the temperature on the downstream side and above in the second casing portion 13 and automatically control the opening / closing door 43 based on the measurement result. That is, an exhaust heat recovery facility capable of more reliably preventing acid dew point corrosion will be provided.

For the above purpose, it is desirable that the bypass flow path 19 is configured to guide the exhaust gas above the center of the second casing portion 13 in the vertical direction.
The reason for this is as follows.
Since a low-temperature heated gas flows in the first casing portion 7 arranged above the second casing portion 13, the temperature of the exhaust gas flowing in the second casing portion 13 is lower as it is closer to the first casing portion 7. Become. Therefore, by providing the second opening 41 which is the outlet of the bypass flow path 19 in the upper region close to the first casing portion 7, the portion in the second casing portion 13 where the temperature is the lowest is concentrated and raised. It can be heated, and the minimum temperature can be raised efficiently and pinpointly. Therefore, it is possible to more reliably prevent the occurrence of acid dew point corrosion and effectively utilize the heat of the exhaust gas.
In this respect, in the present embodiment, the lower end of the second opening 41 is more preferably located above the center of the second casing 13 in the vertical direction, but at least the second opening 41 If the center in the vertical direction is located above the center in the vertical direction of the second casing portion 13, the effect of concentrating and raising the temperature of the portion having a relatively low temperature can be obtained to a certain extent. In other words, the bypass flow path 19 may be configured to guide more exhaust gas to the upper side than the lower side with respect to the center in the vertical direction with respect to the second region in the second casing portion 13.

Further, in the present embodiment, the duct 37 forming the flow path wall forming the bypass flow path 19 has a guide portion 44 for guiding the exhaust gas flowing in the bypass flow path 19 upward, and the guide portion 44 is upstream. The position of the side end (A in FIGS. 1 and 2) is set lower than the position of the downstream end (B in FIGS. 1 and 2). By providing the guide portion 44, the entrance of the bypass flow path 19 can be enlarged, and the exhaust gas can easily flow in the bypass flow path 19 as compared with the case where the guide portion 44 is not provided.

In the exhaust heat recovery facility 1 configured as described above, the exhaust gas temperature in the region where the temperature is most likely to be the lowest in the second region in the second casing portion 13 can be raised, and acid dew point corrosion due to the SOx component can be performed. Can be prevented. Moreover, as in Patent Document 1, a part of the heated gas bypasses the heat exchanger, and the unheated gas is mixed with the preheated gas preheated on the discharge side of the heat exchanger. Compared with the above, it is possible to preheat more gas to be heated, and it is possible to effectively utilize the heat of the exhaust gas by suppressing a decrease in the amount of heat transfer to the gas to be heated.

[Embodiment 2]
Next, as an example of use of the exhaust heat recovery facility 1 configured as described above, a case where it is applied to the hot air furnace facility 45 that blows high temperature air to the tuyere of the blast furnace will be described with reference to FIG.
Since the heat pipe type exhaust heat recovery facility 1 described in the first embodiment can be installed in a more space-saving manner, it is particularly meaningful to apply it to the hot air furnace facility 45, which is often difficult to handle. Is.

In FIG. 5, equipment other than the exhaust heat recovery equipment 1 described in the first embodiment will be outlined. 48 is a hot air furnace composed of a combustion chamber 46 and a heat storage chamber 47, and 49 is supplied to the exhaust heat recovery equipment 1. A blower 51 that blows air, which is a gas to be heated, is a chimney for discharging exhaust gas to the atmosphere. Of the lines connecting each facility, the solid line indicates the line through which the exhaust gas flows (exhaust gas line 53, the exhaust gas bypass line 57, the exhaust heat recovery line 59), and the one-point chain line is the line through which the combustion air supplied to the combustion chamber 46 flows. (Heated gas line 55, heated gas bypass line 81) and a line through which the fuel gas flows (B gas line 75, C gas line 77, fuel gas line 79) are shown, and the two-point chain line shows a control line.

The exhaust gas line 53 is an exhaust gas bypass line 57 connected to the chimney 51 side by bypassing the exhaust heat recovery facility 1 on the downstream side of the heat storage chamber 47, and an exhaust heat recovery line 59 connected to the exhaust heat recovery facility 1 side. Branches to. In the case of a hot air furnace, the temperature of the exhaust gas is about 200 to 300 ° C. as shown in FIG.
The exhaust gas bypass line 57 is provided with a first flow rate adjusting valve 61.
In the exhaust heat recovery line 59, a first on-off valve 63 is provided near the branch point, and a first flow control valve 65 for controlling the first flow rate adjusting valve 61 is provided on the downstream side thereof. Further, a second on-off valve 67 is provided on the downstream side thereof, and is connected to the exhaust gas inflow port 9 of the exhaust heat recovery facility 1 on the downstream side thereof. A third on-off valve 69 is provided on the downstream side of the exhaust gas outlet 11 of the exhaust heat recovery facility 1, and a second flow control valve 70 for controlling the second flow rate adjusting valve 83 described later is provided on the downstream side thereof. Is provided.
The first and second flow control valves 65 and 70 are devices that measure the gas temperature and control the first and second flow rate adjusting valves 61 and 83 based on the measured temperature.
The first flow rate adjusting valve 61 is always in a fully closed state during normal operation. However, when the temperature detected by the first flow control valve control device 65 becomes higher than the operating temperature of the heat pipe, the first flow rate adjusting valve is intended to reduce the amount of heat input to the exhaust heat recovery facility. The opening degree of 61 may be increased. Further, in an emergency such as when a gas leak is detected in the exhaust heat recovery facility 1, or during regular maintenance of the exhaust heat recovery facility 1, the first flow rate adjusting valve 61 is fully opened and the first on-off valve 63 is fully closed. It is also possible to prevent the exhaust gas from flowing to the exhaust heat recovery facility 1.

Regarding the heated gas line 55, a fourth on-off valve 71 is provided on the downstream side of the blower 49, and a fifth on-off valve 72 is provided on the downstream side of the blower 49 and on the upstream side of the heated gas inflow port 3 of the exhaust heat recovery facility 1. Has been done. Further, a sixth on-off valve 73 is provided on the downstream side of the heated gas outlet 5 of the exhaust heat recovery facility 1, and a third flow control valve 74 is provided on the downstream side thereof. In the third flow valve control device 74, the B gas flow rate adjusting valve 76 provided in the B gas line 75 through which the B gas (blast furnace gas) flows and the C gas through which the C gas (coke gas) having a calorific value larger than that of the B gas flows. By controlling the C gas flow rate adjusting valve 78 provided on the line 77, the gas is supplied to the hot air furnace 48 according to the temperature of the combustion air supplied from the exhaust heat recovery facility 1 to the combustion chamber 46 of the hot air furnace 48. It adjusts the ratio of B gas and C gas. The B gas and the C gas are mixed at a ratio adjusted by the third flow control valve control device 74 to become a mixed gas, which flows through the fuel gas line 79 and is supplied to the hot air furnace 48.
In the hot air furnace 48, a mixed gas of B gas and C gas is used as fuel, but C gas is generally more expensive than B gas, and C gas containing a large amount of H ₂ is becoming more widely used. Therefore, it is often desirable to increase the proportion of B gas from the viewpoint of supply and demand. However, when the preheating of the combustion air supplied to the hot air furnace 48 is insufficient and the temperature is low, the flow rate of C gas (combustion amount of C gas) is increased in order to achieve the required temperature of the hot air supplied to the blast furnace. It is necessary to increase the number, and the control for this is performed by the third flow control valve control device 74.

Further, a heated gas bypass line 81 is provided on the downstream side of the fourth on-off valve 71 and on the upstream side of the fifth on-off valve 72 to branch from the heated gas line 55 and bypass the exhaust heat recovery facility 1. The heated gas bypass line 81 is provided with a second flow rate adjusting valve 83.

In the hot air furnace facility 45 configured as described above, the exhaust gas from the heat storage chamber 47 of the hot air furnace 48 is supplied to the exhaust heat recovery facility 1, and the exhaust heat recovery facility 1 recovers this exhaust heat to blower 49. The heated gas, which is the combustion air of the hot air furnace supplied from the above, is preheated and supplied to the combustion chamber 46.
As described in the first embodiment, in the exhaust heat recovery facility 1, the bypass flow path 19 is provided to prevent the occurrence of acid dew point corrosion in the second casing portion 13, but the bypass flow path 19 is used. There may be cases where countermeasures are not sufficient.
Therefore, in the present embodiment, the second flow control valve 70 constantly detects the temperature of the exhaust gas discharged from the exhaust heat recovery facility 1, and the second flow rate adjusting valve provided in the heated gas bypass line 81. It also has a function of controlling 83 to adjust the amount of heated gas supplied to the exhaust heat recovery facility 1.
That is, when the exhaust gas temperature on the outlet side of the second casing portion 13 drops and there is a concern that acid dew point corrosion may occur, the opening degree of the second flow rate adjusting valve 83 is increased and supplied to the exhaust heat recovery facility 1. By reducing the amount of gas to be heated and the amount of heat recovery, it is possible to prevent a temperature drop in the downstream region of the second casing portion 13.
As described above, in the present embodiment, acid dew point corrosion occurs by bypassing the exhaust gas to the downstream side in the exhaust heat recovery facility 1 which can suppress the decrease in the amount of heat transfer from the exhaust gas to the heated gas. In addition to preventing this, when the exhaust gas temperature in the downstream area of the exhaust heat recovery facility 1 cannot be maintained above a certain level, a two-step measure of bypassing the heated gas to the exhaust heat recovery facility 1 is taken. By doing so, the safety of the equipment is guaranteed.

In the present invention, the flow rate of the exhaust gas passing through the bypass flow path 19 may be controlled by automatically adjusting the opening degree of the second opening 41, but the second opening in the exhaust gas bypass flow path 19 It is preferable that the opening / closing door 43 provided in the 41 has a constant opening degree and is used stably. However, if the temperature fluctuation of the exhaust gas is large and it is desired to further improve the temperature controllability, the on-off door 43 may be used as an automatic adjusting valve to automatically control the flow rate. If the exhaust gas temperature on the outlet side does not rise to the set temperature even when the exhaust gas bypass flow rate is controlled by the on-off door 43, the external bypass flow rate control (adjustment) is performed by the second flow rate adjusting valve 83 provided in the heated gas bypass line 81. You may add it.

Further, the opening degree of the second opening 41 in the exhaust gas bypass flow path 19 is set to an opening degree such that the exhaust gas outlet temperature becomes constant or higher when the exhaust gas temperature becomes low while the exhaust gas temperature fluctuates. It is preferable to do so. The reason for this is as follows.
If the opening degree of the second opening 41 in the bypass flow path 19 is set based on the case where the exhaust gas temperature is low, the temperature of the heat receiving portion in the heat pipe 15 rises when the exhaust gas temperature rises. However, when the exhaust gas in contact with the heat receiving portion of the heat pipe 15 changes from a low temperature to a high temperature, the phase conversion cycle of steam and condensed water inside the heat pipe 15 tends to be accelerated and the amount of heat recovered tends to increase. Therefore, even if the opening degree of the second opening 41 in the bypass flow path 19 is fixed, when the exhaust gas temperature rises, the amount of heat recovered in the heat pipe 15 increases, so that the outlet temperature of the exhaust gas rises significantly. Never. As described above, the fact that the outlet temperature fluctuation is suppressed and the exhaust gas outlet temperature does not rise unnecessarily brings about the effect of maximizing the amount of heat recovered by the heat pipe 15.

Further, in the second embodiment described above, an example in which air for burning the fuel gas is preheated as a heated gas has been shown, but the present invention is not limited to these, and the fuel (fuel gas) is used as a heated gas. It may be preheated as.

[Embodiment 3]
In the hot air furnace equipment 45 of the second embodiment, the air for burning the fuel in the combustion chamber 46 was used as the heated gas, but the hot air furnace equipment 84 of the third embodiment uses the air. In addition, the fuel gas (B gas, which is the blast furnace gas), which is the fuel to be burned in the combustion chamber 46, is used as the heated gas.
Specifically, in the present embodiment, in addition to the configuration of the second embodiment, the heated gas line 55-2 that preheats the B gas, which is a fuel gas, as the heated gas, and the exhaust heat in the exhaust gas line 53. In addition to being connected to the recovery line 59-1, it is further provided with a heating gas supply line 85 provided with a heating device 87 such as a burner (see FIG. 6).
The heating gas supply line 85 is provided because the heated gas line 55-2 for preheating the B gas is provided, so that the amount of heat for preheating is insufficient only with the heat of the exhaust gas discharged from the heat storage chamber 47. This is to supplement this amount of heat. Specifically, the high temperature gas is supplied from the temperature rising gas supply line 85 to the exhaust heat recovery line 59-1 in the exhaust gas line 53 by supplying the temperature rising gas heated by the heating device 87. The amount is increased to raise the temperature, and the amount of heat of the exhaust gas supplied to the first exhaust heat recovery facility 1-1 and the second exhaust heat recovery facility 1-2 is increased.

FIG. 6 shows the system of the present embodiment, and the same parts as those of the second embodiment and the corresponding parts are designated by the same reference numerals, and the description thereof will be omitted. However, in order to clarify the correspondence with the second embodiment, for example, the exhaust heat recovery facility 1 of the second embodiment is set to the first exhaust heat recovery facility 1-1, and the exhaust heat recovery added in the third embodiment is used. The equipment shown in the second embodiment is added with "-1" after the main code so that the equipment is the second exhaust heat recovery equipment 1-2, and is added in the corresponding embodiment 3. The device is indicated by adding "-2" after the same main code as used in the second embodiment.

Since the configuration and operation of the equipment related to the second exhaust heat recovery facility 1-2 are the same as those of the first exhaust heat recovery facility 1-1 of the second embodiment, the temperature rising gas added in the present embodiment is described below. The supply line 85 will be described.
That is, in the hot air furnace equipment 84 of the present embodiment, the hot air furnace is connected between the first exhaust heat recovery equipment 1-1 and the second exhaust heat recovery equipment 1-2, and the exhaust gas is first discharged from the hot air furnace. The exhaust gas line 53 supplied to the exhaust heat recovery equipment 1-1 and the second exhaust heat recovery equipment 1-2 is connected to the exhaust heat recovery line 59-1 in the exhaust gas line 53, and a heating device 87 is provided. A first exhaust heat recovery facility 1-1 is further provided with a hot gas supply line 85, and by supplying the heated gas heated by the heating device 87 from the heated gas supply line 85 to the exhaust heat recovery line 59-1. And it is configured to increase the amount of heat of the exhaust gas supplied to the second exhaust heat recovery facility 1-2.
The heating gas supply line 85 includes a heating device 87 such as a burner, an air supply line 89 that supplies combustion air to the heating device 87, and a blower 91 that generates combustion air to be supplied to the air supply line 89. A third flow control valve 93 provided in the air supply line 89 for adjusting the amount of air, a seventh on-off valve 95 provided in the air supply line 89, and a fuel supply line 97 for supplying fuel to the heating device 87. Fuel supplied to the heating device 87 provided between the eighth on-off valve 99 and the ninth on-off valve 101 provided in the fuel supply line 97 and the eighth on-off valve 99 and the ninth on-off valve 101 in the fuel supply line 97. A fourth flow rate adjusting valve 103 for adjusting the supply amount of the fuel is provided.

The third flow rate adjusting valve 93 and the fourth flow rate adjusting valve 103 were mainly provided in the third flow control valve control device 74-1 and the heated gas line 55-2 provided in the heated gas line 55-1. Although it is controlled by the third flow control valve control device 74-2, the third flow control valve 93 and the fourth flow control valve 103 are provided with the first flow control lines 59-1 and 59-2. The signal lines from the valve control devices 65-1 and 65-2 are also connected to adjust the temperature and amount of the heating gas supplied from the heating device 87 when the exhaust gas temperature is too high or too low. be able to.

In the present embodiment configured as described above, the method of preheating the B gas, which is the fuel gas burned in the combustion chamber 46 of the hot air furnace 48, is the method of preheating the air burned in the combustion chamber 46 described in the second embodiment. The method is the same as the preheating method by the first exhaust heat recovery facility 1.
Hereinafter, the operation of the temperature rising gas supply line 85 will be described.
The temperature-increasing gas supply line 85 operates when the amount of heat of the exhaust gas from the heat storage chamber 47 of the hot air furnace 48 is insufficient to preheat both the air and the B gas. Therefore, regarding the amounts of air and fuel supplied to the heating device 87, the third flow control valve control device 74-1 provided in the heated gas line 55-1 and the heated gas line 55-2 are provided. It is controlled by the 3-flow valve control device 74-2.
Thereby, the heating amount, operation and stop of the heating device 87 can be adjusted according to the temperature status of the preheated air and the preheated B gas supplied to the combustion chamber 46 of the hot air furnace 48.

In the present embodiment, by preheating the air and B gas supplied to the combustion chamber 46 of the hot air furnace 48, the fuel gas of the hot air furnace 48 is burned only with B gas, which has a relatively low unit price. It will also be feasible.
That is, when a mixed gas of coke gas (C gas) having a high calorie and a high unit price and a blast furnace gas (B gas) having a low calorie and a low unit price was generally used as the fuel gas for the hot air furnace, the unit price was low. It is possible to increase the proportion of B gas and operate using only B gas. As a result, the cost of fuel gas can be reduced, and it also contributes to the effective use of C gas, which has a wide range of uses.

Although the present invention has been described above using the embodiments, the present invention is not limited to the configurations of these embodiments. The scope of the present invention is determined based on the description of the appended claims, and all of the configurations in which some of the components shown in the embodiments are omitted or modified, or those are improved within the scope of the claims. Is included in the present invention.

For example, in the above embodiment, the case where the equipment for discharging high-temperature exhaust gas that generates sulfuric acid when the temperature drops below the acid dew point is a blast furnace has been described, but as another example of such an apparatus, a coke-drying type is used. Examples include blast furnace ancillary equipment such as fire extinguishing equipment and sintering machines for sintered ore. Further, the present invention is not limited to these facilities, and when used in combination with a facility that emits exhaust gas that may cause a problem of acid dew point corrosion in an exhaust heat recovery facility, the present invention exhibits the above-mentioned excellent effects. It is a thing.

Further, in the above-described embodiment, the bypass flow path 19 is provided on the outer side surface of the exhaust heat recovery facility 1, but the bypass flow path of the present invention is provided inside the second casing portion 13, for example, in the center. It may be provided so as to pass through.

1 Exhaust heat recovery equipment (1st exhaust heat recovery equipment)
1-2 2nd exhaust heat recovery equipment 3 Heated gas inlet 5 Heated gas outlet 7 1st casing 9 Exhaust gas inlet 11 Exhaust gas outlet 13 2nd casing 15 Heat pipe 19 Bypass flow path 21 1st main body Part 23 1st inflow side reduced diameter part 25 1st outflow side reduced diameter part 27 Tube plate 29 2nd main body 31 2nd inflow side reduced diameter part 33 2nd outflow side reduced diameter part 37 Duct 39 1st opening 41 1st 2 Opening 43 Opening / Closing Door 44 Guide 45 Hot Air Furnace Equipment 46 Combustion Room 47 Heat Storage Room 48 Hot Air Furnace 49 Blower 51 Chimney 53 Exhaust Gas Line 55 Heated Gas Line 57 Exhaust Gas Bypass Line 59 Exhaust Heat Recovery Line 61 First Flow Control Valve 63 1st on-off valve 65 1st flow control valve 67 2nd on-off valve 69 3rd on-off valve 70 2nd flow control valve control device 71 4th on-off valve 72 5th on-off valve 73 6th on-off valve 74 3rd flow control Valve control device 75 B gas line 76 B gas flow control valve 77 C gas flow control valve 79 C gas flow control valve 79 Fuel gas line 81 Heated gas bypass line 83 Second flow control valve 84 Hot air furnace equipment 85 Heat-increasing gas supply line 87 Heating device 89 Air supply line 91 Blower (heating gas supply line)
93 3rd flow control valve 95 7th on-off valve 97 Fuel supply line 99 8th on-off valve 101 9th on-off valve 103 4th flow control valve

Claims (8)

It is an exhaust heat recovery facility that preheats the gas to be preheated by the heat of high-temperature exhaust gas that can generate sulfuric acid when the temperature drops below the acid dew point.
A first casing portion having a heated gas inlet and a heated gas outlet,
A second casing portion that is arranged directly below the first casing portion and has an exhaust gas inlet and an exhaust gas outlet.
A plurality of heat pipes in which one end in the longitudinal direction is arranged in the first casing portion and the other end in the longitudinal direction is arranged in the second casing portion.
A first region in the second casing portion, which is a part of a region in which the plurality of heat pipes are arranged, and a part of the region in which the plurality of heat pipes are arranged, which is more than the first region. Of the second region located on the downstream side in the flow direction of the exhaust gas, the second region is provided with a bypass flow path that bypasses the first region, and a part of the exhaust gas does not pass through the first region. A heat pipe type exhaust heat recovery facility characterized by being configured to be installed in. The heat pipe type exhaust heat recovery according to claim 1, wherein the bypass flow path is configured to guide a part of the exhaust gas above the center of the second casing portion in the vertical direction. Facility. The bypass flow path is provided at a first opening provided on the upstream side of the exhaust gas in the flow direction of the exhaust gas from the first region and on the downstream side of the exhaust gas in the flow direction of the exhaust gas from the first region. Has a second opening and
The bypass flow path is formed so as to guide the part of the exhaust gas flowing in from the first opening to the second region through the second opening without passing through the first region. The heat pipe type exhaust heat recovery facility according to claim 1 or 2. The heat pipe type exhaust heat recovery facility according to claim 3, wherein the center of the second opening in the vertical direction is located above the center of the second casing in the vertical direction. The flow path wall forming the bypass flow path has a guide portion for guiding a part of the exhaust gas upward.
The heat pipe type exhaust heat recovery facility according to claim 3 or 4, wherein the guide portion has a position of the end portion on the upstream side lower than the position of the end portion on the downstream side. The heat pipe type exhaust heat recovery facility according to any one of claims 3 to 5, further comprising an opening degree adjusting device configured to be able to adjust the opening degree of the second opening. A hot air furnace for supplying high temperature gas to the blast furnace,
The heat pipe type exhaust heat recovery facility according to any one of claims 1 to 6 is provided.
One of the air and the fuel for burning the fuel in the hot air furnace by the heat of the exhaust gas generated by the heat pipe type exhaust heat recovery facility burning the fuel in the hot air furnace. A hot air furnace facility characterized in that it is configured to preheat the fuel as the gas to be heated. A hot air furnace for supplying high temperature gas to the blast furnace,
The heat pipe type exhaust heat recovery facility according to any one of claims 1 to 6, wherein the fuel is produced in the hot air furnace by the heat of exhaust gas generated by burning the fuel in the hot air furnace. A first exhaust heat recovery facility configured to preheat the air for combustion as the fuel to be heated, and
The heat pipe type exhaust heat recovery facility according to any one of claims 1 to 6, which is burned in the hot air furnace by the heat of the exhaust gas generated by burning the fuel in the hot air furnace. A hot air furnace facility including a second exhaust heat recovery facility configured to preheat the fuel gas which is the fuel to be heated as the heated gas.

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