JP7427761B2 - Heat exchanger, boiler equipped with the same, and heat exchange method - Google Patents

Description

The present invention relates to a heat exchanger, a boiler equipped with the same, and a heat exchange method.

A large boiler that constitutes a thermal power plant or the like has a hollow furnace installed vertically, and a plurality of combustion burners are arranged along the circumferential direction on the wall of the furnace. Further, in a large boiler, a flue is connected vertically above the furnace, and a heat exchanger for generating steam is disposed in the flue. Then, the combustion burner injects a mixture of fuel and air into the furnace to form a flame and generate high-temperature combustion gas that flows into the flue. A heat exchanger is installed in a region where combustion gas flows, and superheated steam is generated by heating water or steam flowing through heat transfer tubes that make up the heat exchanger.

Generally employed heat exchangers have an inlet header and an outlet header connected by a plurality of heat transfer tubes. As an example of a heat exchanger, Patent Document 1 describes a heat exchanger in which heat exchanger tubes are configured in two or more groups, and two or more inlet headers and/or outlet headers are provided for each group. There is. According to this heat exchanger, the flow rate of steam flowing through each of the outlet headers can be suppressed, so that the diameter of each outlet header can be reduced.

Unexamined Japanese Patent Publication No. 2018-9762

As mentioned above, the heat exchanger has an inlet header and an outlet header connected by a plurality of heat transfer tubes. Here, if the flow or temperature of the combustion gas flowing through the flue becomes uneven, there is a possibility that the amount of heat absorbed by each heat exchanger tube differs. In this case, the performance of the heat exchange amount of the heat exchanger decreases, and it is necessary to increase the design temperature of each device constituting the heat exchanger, which may increase equipment costs.

Also, when focusing on the velocity distribution of the fluid (steam) in the inlet header and the outlet header, dynamic pressure distribution due to the velocity difference may occur in each header, and accordingly, the inlet of each heat transfer tube There may be a static pressure difference between the outlet and the outlet. This results in a difference in the flow rate of the fluid (steam) flowing between the individual heat transfer tubes. If the flow rate of steam flowing through the individual heat exchanger tubes is uneven, a difference will occur in the amount of heat absorbed by each heat exchanger tube, further reducing the heat exchange performance of the heat exchanger, and causing the heat exchanger to It is necessary to further increase the design temperature of each device, which may further increase equipment costs.

In the configuration of the heat exchanger described in Patent Document 1, a difference in the flow rate of steam flowing through each heat transfer tube due to the velocity distribution in each header tends to occur, and there is a difference in the flow rate and temperature of the combustion gas mentioned above. If non-uniformity occurs, there may be an excessive difference in the temperature of the steam near the outlet end of each heat exchanger tube. This is because, for example, if a heat transfer tube with a small flow rate of flowing steam is placed in a high temperature side area of the combustion gas, and a heat transfer tube with a large flow rate of flowing steam is placed in a low temperature side area of the combustion gas, the high temperature side area In heat exchanger tubes in the lower region, the amount of heat removed by steam is small and is exposed to a high temperature atmosphere and easily becomes high temperature.On the other hand, in heat transfer tubes in the low temperature region, the amount of heat removed by steam is large and is exposed to a low temperature atmosphere. This is because the temperature tends to be low. Therefore, it is necessary to increase the design temperature of each device constituting the heat exchanger, which may increase equipment costs.

The present invention has been made in view of the above circumstances, and provides a heat exchanger that suppresses the temperature difference between fluids near the outlet end of each heat exchanger tube, a boiler equipped with the same, and a heat exchange method. With the goal.

In order to solve the above problems, the heat exchanger, boiler equipped with the same, and heat exchange method of the present invention employ the following means.
That is, the heat exchanger according to the reference aspect of the present invention includes one or more inlet headers that extend in a predetermined direction and are provided with an inlet communication pipe that communicates with the outside at an end in the predetermined direction; a plurality of outlet headers, each of which is arranged in the predetermined direction and has an outlet end along the predetermined direction; a plurality of heat transfer tubes, the heat transfer tubes being alternately connected to the headers, and having an inlet end connected to one of the inlet headers, the other end being the outlet end connected to one of the outlet headers; The outlet communication pipe and the inlet communication pipe, which are associated with each other through the common heat transfer tube, are provided on the same side in the predetermined direction.

Regarding the heat exchanger of this embodiment, the plurality of heat exchanger tubes are arranged in a predetermined direction, the outlet ends are alternately connected to each outlet header along the predetermined direction, and the heat exchanger tubes are connected to one outlet header. The inlet end of is connected to one inlet header. As a result, for example, when a heat exchanger is installed in the flue inside a boiler that constitutes a thermal power plant, the flow velocity and temperature of the combustion gas flowing through the flue inside the boiler will be uneven in a predetermined direction. Even in non-uniform cases (for example, when the heat exchanger tubes are divided into two regions, a high-temperature side region and a low-temperature side region), the heat transfer tubes placed in the high-temperature side region are alternately arranged along a predetermined direction with respect to each outlet header. At the same time, heat exchanger tubes arranged in the low temperature side region are alternately connected to each outlet header along a predetermined direction. Therefore, fluid (for example, steam) can be concentrated from the heat exchanger tubes arranged in each temperature side region into each outlet header so that the total amount of heat becomes approximately equal and the temperature difference between each outlet header is reduced. Therefore, it is possible to suppress the temperature difference that occurs in the fluid that flows through each heat transfer tube and is collected in each outlet header and then flows out from each outlet communication pipe of each outlet header. In addition, since it is possible to suppress the temperature difference between the fluids flowing out from each outlet connecting pipe, it is possible to suppress the occurrence of temperature unevenness in downstream equipment connected to the outlet connecting pipe, which in turn improves the performance of the entire plant. The decrease can be suppressed.

Further, in addition to the above-described configuration, the outlet communication pipe of the outlet header and the inlet communication pipe of the inlet header, which are associated with a connection relationship using a common heat exchanger tube, are provided on the same side in a predetermined direction. Thereby, the differential pressure distribution between the static pressure distribution along the predetermined direction within the inlet header and the static pressure distribution along the predetermined direction within the outlet header can be made to be substantially uniform along the predetermined direction. The flow velocity of the fluid flowing through the heat exchanger tubes depends on the static pressure difference between the inlet header and the outlet header at the position where the heat exchanger tubes are connected, so it is possible to suppress the difference in the flow velocity of the fluid flowing within each heat exchanger tube. . Further, for example, if the inlet connecting pipe of a certain inlet header and the outlet connecting pipe of an outlet header connected to that inlet header are provided on different sides in a predetermined direction, the inlet header at the position where each heat transfer tube is connected The static pressure difference between the outlet header and the outlet header increases (or decreases) along a predetermined direction. Therefore, a difference in flow velocity occurs in the fluid flowing through each heat transfer tube along a predetermined direction. This results in a difference in the amount of heat absorbed by the flowing fluid depending on the individual heat transfer tubes. In addition to this difference in the amount of heat absorption, when the above-mentioned non-uniformity in the temperature of the combustion gas is added, the temperature difference in the fluid near the outlet end of each heat exchanger tube becomes even larger. Therefore, the performance of the heat exchange amount of the heat exchanger decreases, and it is necessary to increase the design temperature of each device constituting the heat exchanger, which may increase equipment costs. However, by suppressing the difference in flow velocity of the fluid flowing through each heat exchanger tube, it is possible to suppress the temperature difference that occurs between the fluids near the outlet end of each heat exchanger tube.
Furthermore, by providing a plurality of outlet headers, the number of heat exchanger tubes connected to each outlet header can be reduced. This makes it possible to reduce the diameter of the outlet header as the flow rate guided to each outlet header decreases, and also to reduce the space occupied by the heat transfer tubes extending from the outlet header, allowing the flue inside the boiler to This makes it easier to place the heat exchanger.

Further, in the heat exchanger according to the reference aspect of the present invention, the number of the inlet headers is the same as the number of the plurality of outlet headers, and the outlet connecting pipes provided in each of the outlet headers are arranged on the same side in the predetermined direction. It is provided.

For the heat exchanger of this embodiment, the number of inlet headers is the same as the number of outlet headers. This makes it possible to reduce the diameter of the inlet header as the flow rate per inlet header decreases, and also to reduce the space occupied by the heat exchanger tubes that protrude from the inlet header. This makes it easier to place the heat exchanger.
Moreover, the outlet communication pipes provided in each outlet header are provided on the same side in a predetermined direction. As a result, the inlet communication pipe and the outlet communication pipe are concentrated on one side in a predetermined direction, so that workability during assembly of the heat exchanger can be improved.
Also, if the flow rate of fluid flowing through the boiler is large depending on the specifications of the boiler, for example, if there is only one inlet header, in order to allow a large flow rate to flow through, the outer diameter of the inlet header must be increased in order to maintain an appropriate flow velocity. However, as the outer diameter increases, the wall thickness must be increased to increase strength, and the manufacturing process may also increase. By providing a plurality of inlet headers, it is possible to reduce the diameter of the inlet headers as described above, so that such manufacturing problems do not occur. Note that this also applies to the exit header.

Further, in the heat exchanger according to the reference aspect of the present invention, one of the outlet communication pipes provided in each of the outlet headers is connected to at least one other outlet communication pipe in the predetermined direction. They are on different sides.

For the heat exchanger of this embodiment, the number of inlet headers is the same as the number of outlet headers. This makes it possible to reduce the diameter of the inlet header as the flow rate per inlet header decreases, and also to reduce the space occupied by the heat transfer tubes extending from the inlet header, making it easier to arrange the heat exchanger. becomes easier.
Furthermore, one of the outlet communicating pipes provided in each outlet header is provided on a different side in a predetermined direction from at least one other inlet communicating pipe. For example, when there are two inlet headers and two outlet headers, the direction of the inlet connecting pipe of one inlet header and the outlet connecting pipe of one outlet header connected to that one inlet header is the same as that of the other inlet header. The direction of the inlet connecting pipe is different from the direction of the outlet connecting pipe of the other outlet header connected to the other inlet header. That is, there are two pairs of inlet communication pipes and outlet communication pipes, and each pair is located on opposite sides in a predetermined direction. As a result, the inlet connecting pipe and the outlet connecting pipe are not concentrated on one side in a predetermined direction, making it easier to route the pipes connected to them, suppressing the increase in occupied space, and making it easier to arrange the heat exchanger. becomes easier.
In addition, if the flow rate of fluid flowing through the boiler is large depending on the specifications of the boiler, for example, if there is only one inlet header, the outer diameter of the inlet header must be increased to allow a large flow of fluid to flow. As the size increases, the wall thickness must be increased to increase strength, and the manufacturing process may increase. By providing a plurality of inlet headers, it is possible to reduce the diameter of the inlet headers as described above, so that such manufacturing problems do not occur.

Further, in the heat exchanger according to the reference aspect of the present invention, the number of the inlet headers is one, the number of the outlet headers is two, and the inlet communication pipe is provided at both ends of the inlet header, and one of the inlet headers is provided at both ends of the inlet header. The communication pipe and the outlet communication pipe of one of the outlet headers are provided on one side in the predetermined direction, and the other inlet communication pipe and the outlet communication pipe of the other outlet header are provided on one side in the predetermined direction. The flow path area of the inlet header is larger than the flow path area of the outlet header.

Regarding the heat exchanger of this embodiment, the inlet connecting pipes are provided at both ends of one inlet header, and the one inlet connecting pipe and the outlet connecting pipe of one outlet header are provided on one side in a predetermined direction. , the other inlet connecting pipe and the outlet connecting pipe of the other outlet header are provided on different sides in a predetermined direction. This means that the inlet connecting pipe of one inlet header and the outlet connecting pipe of one outlet header are in a pair, and the inlet connecting pipe of the other inlet header and the outlet connecting pipe of the other outlet header are in a pair, and each pair It becomes equivalent to a heat exchanger located on the opposite side in a given direction.
Further, the inlet header is configured to be common, and the inlet header has a larger flow path area than the outlet header. As a result, the inlet connecting pipe and the outlet connecting pipe are not concentrated on one side in a predetermined direction, so that the piping connected to them can be easily routed.
Further, by using two outlet headers, the number of heat exchanger tubes connected to each outlet header can be reduced. This makes it possible to reduce the diameter of the outlet header as the flow rate guided to each outlet header decreases, and also to reduce the space occupied by the heat transfer tubes extending from the outlet header, allowing the flue inside the boiler to This makes it easier to place the heat exchanger.

Further, a boiler according to a reference aspect of the present invention includes the above-mentioned heat exchanger.

Further, a heat exchange method according to a reference aspect of the present invention includes one or more inlet headers extending in a predetermined direction and provided with an inlet communication pipe communicating with the outside at an end in the predetermined direction; a plurality of outlet headers, each of which is arranged in the predetermined direction and has an outlet end along the predetermined direction; a plurality of heat transfer tubes, the heat transfer tubes being alternately connected to the headers, and having an inlet end connected to one of the inlet headers, the other end being the outlet end connected to one of the outlet headers; , the outlet connecting pipe and the inlet connecting pipe are associated with each other by the common heat transfer tube, in a heat exchange method using a heat exchanger provided on the same side in the predetermined direction; a step of flowing a fluid into the inlet header via a tube, a step of circulating the fluid in the heat transfer tube to heat the fluid, and a step of heating the fluid from the outlet header through the outlet connecting tube. and a step of draining.
Further, a heat exchanger according to one aspect of the present invention is a heat exchanger disposed in a flue of a boiler, the inlet communication pipe extending in a predetermined direction and communicating with the outside at an end in the predetermined direction. one or more inlet headers provided with one or more inlet headers; a plurality of outlet headers extending in the predetermined direction and provided with an outlet communication pipe that communicates with the outside only at one end in the predetermined direction; and the outlet ends are alternately connected to each of the outlet headers along the predetermined direction, and the outlet end connected to one outlet header is connected to the other outlet end. a plurality of heat exchanger tubes connected to the inlet header of the heat exchanger tube, and the outlet communication tube is arranged in a region where a difference in the amount of heat absorption in each of the heat exchanger tubes occurs and is associated with the common heat exchanger tube. The inlet communication pipe is provided on the same side in the predetermined direction.
Further, the heat exchange method according to one aspect of the present invention includes one or more inlet headers extending in a predetermined direction and provided with an inlet communication pipe communicating with the outside at an end in the predetermined direction; a plurality of outlet headers each of which is arranged in the predetermined direction and is provided with an outlet communication pipe that extends in the predetermined direction and communicates with the outside only at one end in the predetermined direction; a plurality of heat exchanger tubes that are alternately connected to the headers, and whose inlet ends are connected to one of the inlet headers, with the outlet end being the other end connected to the one of the outlet headers; The outlet connecting pipe and the inlet connecting pipe are associated with each other by the common heat transfer tube, and the heat exchange method uses a heat exchanger provided on the same side in the predetermined direction, The exchanger is arranged in a region in the flue of the boiler where the amount of heat absorption in each of the heat transfer tubes differs, and each of the heat transfer tubes arranged in the predetermined direction has a difference in the amount of heat absorption along the predetermined direction. There is a step of flowing the fluid into the inlet header via the inlet connecting pipe, a step of circulating the fluid in the heat transfer tube to heat the fluid, and a step of flowing the fluid from the outlet header to the outlet connecting pipe. and draining the heated fluid through the heated fluid.

ADVANTAGE OF THE INVENTION According to the heat exchanger, the boiler equipped with the same, and the heat exchange method which concern on this invention, the temperature difference of the fluid near the outlet end of each heat exchanger tube can be suppressed.

It is a diagram showing an example of a boiler equipped with a heat exchanger. FIG. 1 is a schematic longitudinal cross-sectional view of a heat exchanger according to a first embodiment of the present invention. It is a modification of the heat exchanger according to the first embodiment of the present invention. It is a figure showing the pressure distribution in an inlet header and an outlet header. It is a figure showing the pressure distribution in an inlet header and an outlet header. FIG. 3 is a diagram showing a longitudinal cross-sectional view of the exit header. FIG. 3 is a diagram showing a longitudinal cross-sectional view of the exit header. It is a schematic diagram of the longitudinal section of the heat exchanger concerning a 2nd embodiment of the present invention. It is a modification of the heat exchanger according to the second embodiment of the present invention. FIG. 7 is a schematic vertical cross-sectional view of a heat exchanger according to a third embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A heat exchanger, a boiler equipped with the same, and a heat exchange method according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial schematic diagram of a coal-fired boiler 100 (hereinafter simply referred to as "boiler 100") as an example of a thermal power plant suitable for employing a heat exchanger according to an embodiment of the present invention. is shown.

The boiler 100 uses pulverized coal obtained by pulverizing coal by a not-shown pulverizer (mill) as pulverized fuel (carbon-containing solid fuel), combusts this pulverized coal with a combustion burner, and uses the combustion gas generated by this combustion for water supply and This is a coal-fired (pulverized coal-fired) boiler that can generate superheated steam by exchanging heat with steam. In the following description, the term "above" or "upper" refers to the upper side of the page or the upper side in the vertical direction, and the term "bottom" or "lower" refers to the lower side of the page or the lower side in the vertical direction.

The boiler 100 has a furnace 110, a combustion device 114, and a flue 102. The furnace 110 has a hollow rectangular tube shape and is installed along the vertical direction. The furnace wall (heat transfer tube) constituting the furnace 110 is composed of a plurality of evaporation tubes and fins connecting these, and suppresses a rise in temperature of the furnace wall by exchanging heat with water and steam.

The combustion device 114 is provided on the lower side of the furnace wall that constitutes the furnace 110 . In the figure, combustion device 114 includes a plurality of combustion burners 108 mounted on the furnace wall. For example, each combustion burner 108 is arranged in multiple stages along the vertical direction, with a set of combustion burners arranged at equal intervals along the circumferential direction. However, the shape of the furnace, the number of combustion burners in one stage, and the number of stages are not limited to this form.

Each combustion burner 108 is connected to a mill via a pulverized coal supply pipe (not shown). The mill is configured such that, for example, a rotary table is rotatably supported within a housing, and a plurality of rollers are supported vertically above the rotary table so as to be rotatable in conjunction with the rotation of the rotary table. When coal is placed between a plurality of rollers and a rotary table, it is crushed into a predetermined size of pulverized coal, and the pulverized coal is classified by a conveying gas (primary air) and transferred to a pulverized coal supply pipe (not shown). can be supplied to each combustion burner 108 from.

Further, the furnace 110 is provided with a wind box 116 at the mounting position of each combustion burner 108. The air box 116 is connected to the other end of an air duct 118 that is provided with a blower (not shown) at one end.

The flue 102 is connected to the upper part of the furnace 110. This flue 102 is provided with a superheater 104, a reheater 106, and a economizer 112 as heat exchangers for recovering the heat of the combustion gas. Heat exchange is performed between the heat exchanger and the feed water or steam flowing through each heat exchanger.

[First embodiment]
Next, a heat exchanger 1A according to a first embodiment of the present invention will be explained using the drawings.

The heat exchanger 1A is a suitable heat exchanger that is employed, for example, in the superheater 104 and reheater 106 disposed in the flue 102 of the boiler 100 shown in FIG.

As shown in FIG. 2, the heat exchanger 1A includes one inlet header 10, two outlet headers 20, and a plurality of heat transfer tubes 40.

The inlet header 10 is, for example, a cylindrical tubular member extending in a predetermined direction that corresponds to the left-right direction in the drawing. The inlet header 10 is made of metal such as low alloy steel, high alloy steel, stainless steel, or the like. An inlet communication pipe 12 is provided at an end of the inlet header 10 to communicate an inlet channel 14 formed within the inlet header 10 with the outside of the inlet header 10. In the case of the figure, the inlet communication pipe 12 is provided only at one end in a predetermined direction (the left end in the drawing). On the other hand, the other end (the right end in the drawing) where the inlet communication pipe 12 is not provided is closed.

Like the inlet header 10, the outlet header 20 is a cylindrical tubular member that extends in a predetermined direction that corresponds to the left-right direction in the drawing. The outlet header 20 is made of metal such as low alloy steel, high alloy steel, stainless steel, or the like. The outlet header 20 is provided above the inlet header 10 in the drawing. In the figure, there are two exit headers 20. In the following description, when it is necessary to distinguish between them, the symbols 20a and 20b will be used, and for matters common to each exit header 20, the symbol 20 will simply be used. An outlet communication pipe 22 is provided at an end of the outlet header 20 to communicate an outlet flow path 24 formed within the outlet header 20 with the outside of the outlet header 20. In the case of the figure, each outlet communication pipe 22 of the first outlet header 20a and the second outlet header 20b is provided only at one end on the same side as the inlet communication pipe 12 in a predetermined direction. On the other hand, the other end (the right end in the drawing) where the outlet communication pipe 22 is not provided is closed.

The inlet header 10 and each outlet header 20 described above are connected by a plurality of heat transfer tubes 40, respectively.

The heat exchanger tube 40 is a tubular member that extends in the vertical direction of the plane of the drawing. The heat exchanger tube 40 is made of metal such as low alloy steel, high alloy steel, stainless steel, etc., for example. The upper end of the heat exchanger tube 40 (ie, the end on the outlet header 20 side) is open and serves as an outlet end. On the other hand, the lower end of the heat exchanger tube 40 (ie, the end on the inlet header 10 side) is also open and serves as an inlet end. A heat exchange channel 41 is formed in the heat exchanger tube 40, and a fluid flows therethrough. The flowing fluid is, for example, water or steam, and in this embodiment, it is steam. The plurality of heat exchanger tubes 40 are arranged along a predetermined direction at predetermined intervals. In the figure, eight heat exchanger tubes 40 are arranged in a predetermined direction, but in reality, approximately 100 to 1000 heat exchanger tubes 40 may be arranged.

Each outlet end of the plurality of heat exchanger tubes 40 is alternately connected to the first outlet header 20a and the second outlet header 20b along a predetermined direction. Specifically, the first outlet header 20a, the second outlet header 20b (hereinafter in the same order), etc. are connected alternately in order from the heat exchanger tube 40 on the left side in the figure. For example, when there are three outlet headers 20, as shown in FIG. 3, the first outlet header 20a, second outlet header 20b, and third outlet header 20c (hereinafter the same) They will be connected alternately as follows. In short, the outlet end of a certain heat exchanger tube 40 is configured to be connected to an outlet header 20 different from the outlet header 20 to which the adjacent heat exchanger tube 40 is connected. In other words, when there are three outlet headers 20, for example, from the heat exchanger tube 40 on the left side, the second outlet header 20b, the first outlet header 20a, the third outlet header 20c (hereinafter in the same order), etc. are alternately arranged. or other combinations may be used.

On the other hand, each inlet end of the plurality of heat exchanger tubes 40 is connected to the inlet header 10 along a predetermined direction, as shown in FIG. In the case of the figure, all the heat exchanger tubes 40 connected to the two outlet headers 20 are connected to the inlet header 10. That is, the first outlet header 20a and the second outlet header 20b are associated with each other in a connection relationship through the inlet header 10 and the heat transfer tube 40, respectively.

Here, the operation of the steam (fluid) flowing through the heat exchanger 1A will be explained.
The steam that has flowed into the inlet channel 14 in the inlet header 10 via the inlet communication pipe 12 flows into each heat transfer tube 40 .

As described above, the heat exchanger 1A is installed in the flue 102 through which the high temperature combustion gas generated in the furnace 110 flows. Therefore, the steam flowing through the heat exchange channel 41 in each heat transfer tube 40 is heated and its temperature increases by exchanging heat with the combustion gas flowing around the heat transfer tube 40.

The heated steam flows from the heat exchanger tubes 40 into the outlet channels 24 in each outlet header 20 and is concentrated therein. The concentrated steam is taken out from respective outlet communication pipes 22 provided in each outlet header 20.

At this time, even if the flow velocity or temperature of the circulating combustion gas is uneven in a predetermined direction (for example, when it is divided into two regions, a high temperature side region and a low temperature side region), each temperature side Steam can be concentrated from the heat exchanger tubes 40 arranged in the region into each outlet header 20 so that the total amount of heat becomes approximately equal. This is because the heat exchanger tubes 40 arranged along a predetermined direction are connected alternately (in a regular order) to each outlet header 20, so the plurality of heat exchanger tubes 40 located in each temperature side region are , are connected to each outlet header 20 in approximately equal numbers. In the case of FIG. 2, two of the four heat exchanger tubes 40 located in the high temperature side region are connected to the first outlet header 20a, and two are connected to the second outlet header 20b. The same applies to the four heat exchanger tubes 40 located in the low temperature side region.

The cross-sectional area of the inlet flow path 14 of the inlet header 10 in the flow direction and the cross-sectional area of the two outlet flow paths 24 of each outlet header 20 in the flow direction are set according to the flow rate of steam passing therethrough. Here, the cross-sectional area of the inlet flow path 14 may be configured to be smaller than the sum of the cross-sectional areas of the two outlet flow paths 24. For example, compared to the steam existing in the inlet flow path 14 of the inlet header 10, the temperature of the steam existing in the outlet flow path 24 of the outlet header 20 is higher due to heat exchange with the combustion gas, and the volume is higher. The flow rate also increases. For this reason, in anticipation of an increase in the volumetric flow rate, the total cross-sectional area of the two outlet flow paths 24 is made larger than the cross-sectional area of the inlet flow path 14 (that is, the cross-sectional area of the inlet flow path 14 is made larger than the cross-sectional area of the two outlet flow paths 24). (smaller than the total cross-sectional area), the flow velocity distribution of steam along a predetermined direction, which will be described later, can be easily made substantially uniform. Note that the cross-sectional areas of each outlet flow path 24 may be configured to approximately match.

Next, the flow velocity distribution of steam (fluid) flowing through the heat exchange channel 41 in each heat exchanger tube 40 will be explained using FIG. 4. In addition, in this description, for the sake of simplicity, an example will be described in which there is only one inlet header 10 and one outlet header 20.

The flow velocity of steam along a predetermined direction in the inlet channel 14 of the inlet header 10 becomes slower from one end where the inlet communication pipe 12 is provided to the other end (from the left end to the right end in the drawing). This is because the steam that has flowed into the inlet header 10 flows out into the outlet header 20 via the heat transfer tubes 40, so that the steam in the inlet channel 14 flows from one end where the inlet communication pipe 12 is provided to the other end. This is due to the gradual decrease in the flow rate. With this change in flow velocity, the dynamic pressure distribution of steam along a predetermined direction in the inlet channel 14 decreases from one end to the other end (solid line shown in graph (a)). Here, if the flow rate of steam flowing into the inlet flow path 14 does not change, the total pressure of the inlet flow path 14 is constant regardless of the position, and the steam flow rate gradually decreases from one end to the other. Considering this, the static pressure distribution of steam along the predetermined direction in the inlet flow path 14 increases from one end to the other end (dotted line shown in graph (a)).

On the other hand, the flow rate of steam in the outlet channel 24 increases from the other end toward one end where the outlet communication pipe 22 is provided (from the right end to the left end in the drawing). This is because the amount of steam in the outlet channel 24 gradually increases from the other end toward the one end where the outlet communication pipe 22 is provided. With this change in flow velocity, the dynamic pressure distribution of steam along a predetermined direction in the outlet channel 24 decreases from one end to the other end (solid line shown in graph (b)). Here, if the flow rate of steam flowing into the outlet flow path 24 does not change, the total pressure of the outlet flow path 24 is constant regardless of the position, and the flow rate of steam gradually increases from the other end to one end. Considering this, the static pressure distribution of steam along the predetermined direction in the outlet flow path 24 increases from one end to the other end (dotted line shown in graph (b)).

The flow rate of steam flowing through each heat transfer tube 40 depends on the pressure difference between the static pressure in the inlet flow path 14 and the static pressure in the outlet flow path 24. Specifically, the flow rate of steam flowing through the plurality of heat transfer tubes 40 arranged along a predetermined direction is determined by the static pressure distribution of the inlet flow path 14 and the static pressure distribution of the outlet flow path 24 along the predetermined direction. depends on the differential pressure of The static pressure distribution of the inlet flow path 14 and the static pressure distribution of the outlet flow path 24 along the predetermined direction both increase from one end toward the other end, as described above. Therefore, the distribution of the static pressure difference becomes a distribution in which the uniformity improves along the predetermined direction and there are no large differences (graph (c)). Therefore, the difference in flow velocity of steam passing through each heat exchanger tube 40 due to the position of each heat exchanger tube 40 along a predetermined direction is suppressed, and the flow velocity distribution of steam passing through each heat exchanger tube 40 along a predetermined direction is suppressed. is approximately equalized. Therefore, the temperature difference that occurs between the fluids near the outlet end of each heat exchanger tube 40 can be suppressed, and the performance of the heat exchanger is improved. Moreover, there is no need to increase the design temperature of each heat exchanger tube 40 more than necessary, and equipment costs can be reduced.

On the other hand, unlike in FIG. The flow velocity is as follows.

That is, as shown in FIG. 5, the steam dynamic pressure distribution and static pressure distribution along the predetermined direction in the inlet flow path 14 of the inlet header 10 are similar to the graph (a) of FIG. 4, and the steam dynamic pressure distribution decreases from one end to the other (solid line shown in graph (a)). Further, the static pressure distribution of steam along the predetermined direction in the inlet channel 14 increases from one end to the other end (dotted line shown in graph (a)). On the other hand, the dynamic pressure distribution and static pressure distribution of steam along the predetermined direction in the outlet flow path 24 differ from the graph (b) of FIG. 4, and show a tendency opposite to that of FIG. 4 in the predetermined direction. That is, the dynamic pressure distribution of steam increases from one end to the other end (solid line shown in graph (b)). Further, the static pressure distribution of steam along a predetermined direction in the outlet flow path 24 decreases from one end to the other end (dotted line shown in graph (b)). The static pressure difference between the static pressure distribution in the inlet flow path 14 and the static pressure distribution in the outlet flow path 24 is a distribution that increases greatly along a predetermined direction (graph (c)). Therefore, due to the position of each heat exchanger tube 40 along the predetermined direction, a flow velocity difference occurs in the steam flowing through each heat exchanger tube 40. In the case of the figure, the flow rate of steam flowing through the heat exchanger tube 40 on the right side is faster than that in the heat exchanger tube 40 on the left side of the paper. Therefore, the temperature difference generated between the fluids near the outlet end of each heat exchanger tube 40 increases, and the performance of the heat exchanger decreases. Furthermore, in the case of the figure, the design temperature needs to be increased due to the temperature rise of each heat exchanger tube 40 on the right side of the drawing, which increases equipment costs.

This embodiment has the following effects.
When the heat exchanger 1A is installed in the flue 102 of the boiler 100, as shown in FIG. Even if the heat exchanger tubes 40 disposed in each temperature side area are divided into two areas (high temperature side area and low temperature side area), the total amount of heat is approximately equal from the heat transfer tubes 40 arranged in each temperature side area into each outlet header 20, and each outlet Steam can be concentrated so that the temperature difference between the headers 20 is reduced. Therefore, it is possible to suppress the temperature difference that occurs in the steam that flows through each heat transfer tube 40 and is collected in each outlet header 20 and then flows out from each outlet communication pipe 22. In addition, since the temperature difference between the steam flowing out from each outlet connecting pipe 22 can be suppressed, it is possible to suppress the occurrence of temperature non-uniformity in downstream equipment connected to the outlet connecting pipe 22, thereby improving the performance of the entire plant. It is possible to suppress the decrease in

Moreover, the difference in flow velocity of steam flowing through the heat exchange channels 41 in each heat exchanger tube 40 can be suppressed. Further, for example, if a difference in flow velocity occurs in the steam flowing through the heat exchange channel 41, a difference will occur in the amount of heat absorbed by the steam flowing through the individual heat exchanger tubes 40. In addition to this difference in the amount of heat absorption, when the above-mentioned non-uniformity in temperature of the combustion gas is added, the temperature difference in the steam near the outlet end of each heat exchanger tube 40 becomes even larger. For this reason, the performance of the heat exchange amount as a heat exchanger decreases, and it is necessary to increase the design temperature of each device configured as a heat exchanger, which may increase equipment costs. However, in the heat exchanger 1A of the present embodiment, by suppressing the difference in flow velocity of the steam flowing through the heat exchange channel 41 in each heat exchanger tube 40, the difference in the flow rate that occurs between the steam near the outlet end of each heat exchanger tube 40 is suppressed. Temperature differences can be suppressed. Furthermore, the flow rate of steam concentrated in each outlet header 20 can be made substantially uniform.

Furthermore, by providing a plurality of outlet headers 20, the number of heat exchanger tubes 40 connected to each outlet header 20 can be reduced. As a result, the diameter of the outlet header 20 can be reduced as the flow rate guided to each outlet header 20 is reduced. Furthermore, the space occupied by the heat exchanger tubes 40 extending from the outlet header 20 can be reduced. For example, when there is one outlet header 20, it is assumed that the heat exchanger tubes 40 are connected as shown in the cross-sectional view of FIG. However, by setting the number of outlet headers 20 to two, for example, the number of heat exchanger tubes 40 connected to each outlet header 20 can be halved as shown in the cross-sectional view of FIG. 7. This reduces the space occupied by the heat exchanger tubes 40 extending from each outlet header 20. Therefore, the heat exchanger 1A can be easily arranged in the flue 102 of the boiler 100.

[Second embodiment]
Next, a heat exchanger 1B according to a second embodiment of the present invention will be described. This embodiment differs from the first embodiment in the form of the entrance header, but is similar in other respects. Therefore, only the points that are different from the first embodiment will be explained, and the same reference numerals will be used for the others, and the explanation thereof will be omitted.

As shown in FIG. 8, the heat exchanger 1B includes two inlet headers 10. In the following description, when it is necessary to distinguish between them, the numbers 10a and 10b are used, and when it is common to each entry header 10, the number 10 is simply used.

Each inlet communication pipe 12 of the first inlet header 10a and the second inlet header 10b is provided only at one end on the same side as the outlet communication pipe 22 in a predetermined direction. In the case of the figure, all the inlet communication pipes 12 and the outlet communication pipes 22 are provided on the same side in a predetermined direction (on the left side of the paper in the figure).

Each inlet end of the plurality of heat exchanger tubes 40 is alternately connected to the first inlet header 10a and the second inlet header 10b. In detail, the heat exchanger tubes 40 on the left side of the drawing are connected alternately (in a regular order) like the first inlet header 10a, the second inlet header 10b (hereinafter in the same order), etc. ing.

At this time, all the heat exchanger tubes 40 connected to the first outlet header 20a are connected to one inlet header 10 (first inlet header 10a in the figure) and are associated with a connection relationship. Further, all the heat exchanger tubes 40 connected to the second outlet header 20b are connected to another inlet header 10 (second inlet header 10b in the figure) and are associated with a connection relationship. That is, all the heat exchanger tubes 40 connected to one outlet header 20 are connected to one inlet header 10 without being connected to a plurality of inlet headers 10, and are associated with each other in a connection relationship. All the heat exchanger tubes 40 connected to other outlet headers 20 are connected to other inlet headers 10 without being connected to a plurality of inlet headers 10, and are associated with each other in a connection relationship.

Note that, as shown in the modified example of FIG. 9, it is not necessary to provide all the inlet communication pipes 12 and outlet communication pipes 22 on the same side in a predetermined direction, and the inlet header 10 with which the connection relationship is matched by the heat transfer tubes 40 is It is sufficient that the inlet communication pipe 12 and the outlet communication pipe 22 of the outlet header 20 are provided on the same side in a predetermined direction. This becomes clear when considering the flow velocity distribution of steam flowing through the heat exchange channels 41 of each heat exchanger tube 40 along a predetermined direction as described above. In the case of the figure, a connection relationship is established by each heat exchanger tube 40 connected between the first inlet header 10a and the first outlet header 20a, and a connection relationship is established between the second inlet header 10b and the second outlet header 20b. Connection relationships are associated with each connected heat exchanger tube 40.

This embodiment has the following effects.
Steam can be concentrated from the heat transfer tubes 40 arranged in each temperature side region into each outlet header 20 so that the total amount of heat becomes approximately equal and the temperature difference between each outlet header 20 is reduced. Therefore, it is possible to suppress the temperature difference that occurs in the steam that flows through the heat exchanger tubes 40 and is collected in each outlet header 20 and then flows out from each outlet communication tube 22.

Moreover, the difference in flow velocity of steam flowing through the heat exchange channels 41 in each heat exchanger tube 40 can be suppressed. Therefore, the temperature difference that occurs in the steam near the outlet end of each heat transfer tube 40 can be suppressed. Furthermore, the flow rate of steam concentrated in each outlet header 20 can be made substantially uniform.

Furthermore, since there are a plurality of outlet headers 20, it is possible to reduce the diameter of each outlet header 20 as the flow rate guided to each outlet header 20 decreases, and the heat transfer tubes 40 protruding from each outlet header 20 can be made smaller. The space occupied can be reduced. Therefore, the heat exchanger 1B can be easily arranged in the flue 102 of the boiler 100.

Furthermore, since there are a plurality of inlet headers 10, it is possible to reduce the diameter of each inlet header 10 as the flow rate flowing through each inlet header 10 decreases, and the heat transfer tubes 40 protruding from each inlet header 10 can be made smaller. The space occupied can be reduced. Therefore, the heat exchanger 1B can be easily arranged in the flue 102 of the boiler 100.

Further, when the outlet connecting pipes 22 provided in each outlet header 20 are provided on the same side in a predetermined direction, the inlet connecting pipe 12 and the outlet connecting pipe 22 are gathered on the same side in the predetermined direction, so that heat It is possible to improve work efficiency when assembling the exchanger.

In addition, when the outlet connecting pipe 22 provided in the first outlet header 20a is provided on a different side in a predetermined direction from the outlet connecting pipe 22 provided in the second outlet header 20b, the inlet is located on one side in the predetermined direction. Since the communication pipe 12 and the outlet communication pipe 22 are not consolidated, the piping connected thereto can be easily routed.

In addition, when the flow rate of steam is large depending on the specifications of the boiler 100, for example, in the case where there is only one inlet header 10, in order to distribute a large flow rate of steam, the outer diameter of the inlet header 10 may be adjusted to obtain an appropriate flow rate. However, as the outer diameter increases, the wall thickness must be increased to increase strength, and the manufacturing process may increase. By providing a plurality of inlet headers 10, it is possible to reduce the diameter of the inlet headers 10 as described above, so such manufacturing problems do not occur.

[Third embodiment]
Next, a heat exchanger 1C according to a third embodiment of the present invention will be described. This embodiment is different from the first embodiment and the second embodiment in the form related to the entrance header, and is the same in other respects. Therefore, only the points that are different from the first embodiment and the second embodiment will be described, and the same reference numerals will be used for the others, and the description thereof will be omitted.

As shown in FIG. 10, the heat exchanger 1C includes one third inlet header 10c. Similar to the first embodiment, two outlet headers 20 are connected to this third inlet header 10c by heat exchanger tubes 40. That is, the first outlet header 20a and the second inlet header 10b are each associated with the third inlet header 10c in a connection relationship.

At this time, the outlet communication pipe 22 of the first outlet header 20a is provided in a different predetermined direction from the outlet communication pipe 22 of the second outlet header 20b. Further, the inlet communication pipes 12 of the third inlet header 10c are provided at both ends in a predetermined direction so that the connection relationship corresponds to each outlet communication pipe 22.

Although there is one third inlet header 10c, the inlet connecting pipe 12 at one end of the third inlet header 10c (on the left side of the drawing) is the outlet of the outlet header 20b connected to the third inlet header 10c. The directions of the communication pipes 22 are on the same side. In addition, the inlet connecting pipe 12 at the other end of the third inlet header 10c (on the right side of the paper in the figure) is on the same side as the outlet connecting pipe 22 of the outlet header 20a connected to the third inlet header 10c. It is something. Furthermore, the third inlet header 10c is configured as a common one. In other words, the inlet connecting pipe 12 at one end of the third inlet header 10c and the outlet connecting pipe 22 of the outlet header 20b are in a pair, and the inlet connecting pipe 12 at the other end of the third inlet header 10c and the outlet connecting pipe 22 of the outlet header 20a are paired. There are outlet connecting pipes 22 in pairs. This means that the inlet connecting pipe of one inlet header and the outlet connecting pipe of one outlet header are in a pair, and the inlet connecting pipe of the other inlet header and the outlet connecting pipe of the other outlet header are in a pair, and each pair It becomes equivalent to a heat exchanger located on the opposite side in a given direction. In other words, the first inlet header 10a and the second inlet header 10b of the heat exchanger 1B according to the second embodiment shown in FIG. 9 are provided as a third inlet header 10c which is one common inlet header. becomes equivalent to

At this time, the passage area of the third inlet header 10c may be larger than the passage area of the outlet header 20. For example, it is preferable to increase the flow path area by increasing the inner diameter of the third inlet header 10c. The flow path area of the third inlet header 10c is appropriate depending on the size of the heat exchanger 1C, the steam flow rate, the flow path cross-sectional area of the heat exchange flow path 41 of each heat transfer tube 40, the length in a predetermined direction of the third inlet header 10c, etc. More preferably, the flow path area of the third inlet header 10c is 1 to 2 times the flow path area of the outlet header 20. When the flow path area of the third inlet header 10c is increased, the overall steam flow rate decreases. This suppresses non-uniformity of the dynamic pressure distribution in the inlet channel 14 along the predetermined direction depending on the flow velocity. Therefore, the static pressure difference distribution between the inlet flow path 14 and the outlet flow path 24 along the predetermined direction is made substantially uniform, and the difference in steam flow velocity caused by the position of each heat transfer tube 40 along the predetermined direction is suppressed. . Note that the configuration in which the flow path area of the inlet header 10 is increased in this way can also be applied to the first embodiment and the second embodiment.

This embodiment has the following effects.
Steam can be concentrated into each outlet header 20 from the heat transfer tubes 40 disposed in each temperature steam region so that the total amount of heat becomes approximately equal and the temperature difference between each outlet header 20 is reduced. Therefore, it is possible to suppress the temperature difference that occurs in the steam that flows through the heat exchanger tubes 40 and is collected in each outlet header 20 and then flows out from each outlet communication tube 22.

Furthermore, since there are a plurality of outlet headers 20, it is possible to reduce the diameter of each outlet header 20 as the flow rate guided to each outlet header 20 decreases, and the heat transfer tubes 40 protruding from each outlet header 20 can be made smaller. The space occupied can be reduced. Therefore, the heat exchanger 1C can be easily arranged in the flue 102 of the boiler 100.

Further, the outlet communication pipe 22 provided in the first outlet header 20a is provided on a different side in a predetermined direction from the outlet communication pipe 22 provided in the second outlet header 20b, and the inlet communication pipe 12 is provided in the third inlet header 10. are provided at both ends. For this reason, the inlet connecting pipe 12 and the outlet connecting pipe 22 are not concentrated on one side in a predetermined direction, so that the piping connected thereto can be easily routed. Therefore, the heat exchanger 1C can be easily arranged in the flue 102 of the boiler 100.

Moreover, when the flow path area in the third inlet header 10c is increased, the difference in flow speed of steam flowing through the heat exchange flow path 41 in each heat transfer tube 40 can be suppressed. Therefore, the temperature difference that occurs in the steam near the outlet end of each heat transfer tube 40 can be suppressed. Furthermore, the flow rate of steam concentrated in each outlet header 20 can be made substantially uniform.

The present invention is not limited to the inventions according to the embodiments described above, and can be modified as appropriate without departing from the gist thereof.
For example, in each of the above embodiments, an example in which the present invention is applied to a coal-fired boiler as an example of a thermal power plant has been described, but the present invention also applies to a gas-fired boiler, an oil-fired boiler, and a heat recovery boiler (HRSG). It may also be applied to equipment equipped with a heat exchanger, such as Recovery Steam Generator) and fluidized bed boilers (BFB).

1 (1A, 1B, 1C) Heat exchanger 10 Inlet header 10a (10) First inlet header (inlet header)
10b (10) Second entrance header (entrance header)
10c (10) Third entrance header (entrance header)
12 Inlet communication pipe 14 Inlet channel 20a (20) First outlet header (outlet header)
20b (20) Second exit header (exit header)
20c (20) Third exit header (exit header)
22 Outlet communication pipe 24 Outlet channel 40 Heat exchanger tube 41 Heat exchange channel

Claims (12)

A heat exchanger placed in a flue of a boiler,
one or more inlet headers extending in a predetermined direction and provided with an inlet communication pipe communicating with the outside at an end in the predetermined direction;
a plurality of outlet headers extending in the predetermined direction and provided with an outlet communication pipe that communicates with the outside only at one end in the predetermined direction;
inlets arranged in the predetermined direction, outlet ends being alternately connected to each of the outlet headers along the predetermined direction, and with the outlet end being connected to one outlet header and the other end thereof being connected to each outlet header; a plurality of heat transfer tubes having ends connected to one of the inlet headers;
Equipped with
arranged in a region where a difference occurs in the amount of heat absorption in each of the heat exchanger tubes,
In the heat exchanger, the outlet communication pipe and the inlet communication pipe, which are associated with each other through the common heat transfer tube, are provided on the same side in the predetermined direction. The number of inlet headers is equal to the number of the plurality of outlet headers,
The heat exchanger according to claim 1, wherein the outlet communication pipes provided in each of the outlet headers are provided on the same side in the predetermined direction. The heat exchanger according to claim 2, wherein one of the outlet communication pipes provided in each of the outlet headers is provided on a different side in the predetermined direction from at least one other outlet communication pipe. exchanger. The number of the inlet headers is one,
There are two exit headers,
The inlet communication pipe is provided at both ends of the inlet header,
One of the inlet communication pipes and one of the outlet communication pipes of the outlet header are provided on one side in the predetermined direction,
The other inlet connecting pipe and the outlet connecting pipe of the other outlet header are provided on other sides in the predetermined direction,
The heat exchanger according to claim 1, wherein the flow path area of the inlet header is larger than the flow path area of the outlet header. The heat exchanger according to claim 1, wherein the heat exchanger is arranged in an area where the flow of combustion gas is uneven. The heat exchanger according to claim 1, wherein the heat exchanger is arranged in a region where the flow velocity of combustion gas is uneven. The heat exchanger according to any one of claims 1 to 6, which is a superheater or a reheater. A boiler comprising the heat exchanger according to any one of claims 1 to 7. one or more inlet headers extending in a predetermined direction and provided with an inlet communication pipe communicating with the outside at an end in the predetermined direction;
a plurality of outlet headers extending in the predetermined direction and provided with an outlet communication pipe that communicates with the outside only at one end in the predetermined direction;
inlets arranged in the predetermined direction, outlet ends being alternately connected to each of the outlet headers along the predetermined direction, and with the outlet end being connected to one outlet header and the other end thereof being connected to each outlet header; a plurality of heat transfer tubes having ends connected to one of the inlet headers;
Equipped with
The outlet connecting pipe and the inlet connecting pipe are associated with each other through the common heat transfer tube, and the heat exchange method uses a heat exchanger provided on the same side in the predetermined direction,
The heat exchanger is arranged in a region in the flue of the boiler where a difference occurs in the amount of heat absorption in each of the heat exchanger tubes,
flowing fluid into the inlet header via the inlet connecting pipe;
heating the fluid by flowing the fluid through the heat transfer tube;
draining the heated fluid from the outlet header through the outlet connecting pipe;
heat exchange methods including; 10. The heat exchange method according to claim 9, wherein the heat exchanger is placed in an area where the flow of combustion gas is uneven. 10. The heat exchange method according to claim 9, wherein the heat exchanger is arranged in a region where the flow rate of combustion gas is uneven. 12. The heat exchange method according to claim 9, wherein the heat exchanger is a superheater or a reheater.