TW202124898A - Gas-gas heat exchanger - Google Patents

Abstract

In the present invention, a plurality of columns of heat exchange bundles 41 are formed by heat transfer tube groups in which a plurality of linear tube parts 45 of heat transfer tubes 12 are arranged side by side in block shapes separated from each other. The heat exchange bundles are disposed in a serial arrangement in a plurality of columns, from the upstream side of exhaust gas to the downstream side. In each of the plurality of columns of the heat exchange bundles 41, the plurality of linear tube parts 45 are disposed so as to intersect the exhaust gas flow direction. The plurality of heat exchange bundles 41 include a tube pattern hybrid bundle 41A in which a first array tube group 51, in which the tube pattern of the plurality of linear tube parts 45 in a tube orthogonal cross-section that is substantially orthogonal to the linear tube parts 45 is a first array, and a second array tube group 52, in which the tube pattern of the plurality of linear tube parts 45 provided on the downstream side of the first array tube group 51 is a second array differing from the first array, are provided in the same bundle and form a heat transfer tube group.

Description

Gas to gas heat exchanger

The present invention relates to a gas-to-gas heat exchanger that performs heat exchange between a heat medium and exhaust gas.

In order to treat exhaust gas (exhaust gas) from boilers used in thermal power plants, etc., it is known to install an air preheater, GGH heat recovery device, dust collection device, wet flue gas desulfurization device, and Exhaust gas treatment system for GGH reheater. In the GGH heat recovery device, heat recovery from the exhaust gas is performed, and in the wet flue gas desulfurization device, a part of sulfur oxides and coal dust in the exhaust gas is removed by gas-liquid contact. In the wet flue gas desulfurization device, the exhaust gas cooled to the saturated gas temperature is heated by the heat recovered by the GGH heat recovery device in the GGH reheater, and then discharged from the chimney.

Patent Document 1 describes that in the exhaust gas treatment system described above, the gas flow path of the GGH reheater is divided into an upstream zone on the upstream side, a downstream zone on the downstream side, and a midstream zone between the upstream zone and the downstream zone. In the upstream, midstream, and downstream regions, separate heat exchange packages (upstream, midstream, and downstream) are arranged. The so-called heat exchange package is a structure of a heat transfer tube group formed by combining the heat transfer tubes to block (unitize) the heat transfer tube as a constituent unit of the heat transfer tube in which the heat medium flows. Patent Document 1 discloses that each of the upstream, midstream, and downstream packages is composed of three layers of heat exchange packages (upper package, middle package, and lower package) stacked one above the other example.

In addition, Patent Document 1 describes that the heat transfer tube arrangement pattern of the upstream package of the GGH reheater is staggered, and the heat transfer tube arrangement pattern of the midstream package and the downstream package is a square arrangement. The bales are connected to an example of a structure in which the heat medium flows from the upstream package to the middle package through the downstream package. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2018/139669

[The problem to be solved by the invention]

In the GGH reheater of Patent Document 1, the upstream package, midstream package, and downstream package function as a high-temperature preheating section, a low-temperature section, and a high-temperature section, respectively, and the introduced exhaust gas is sequentially circulated in a staggered arrangement The high temperature preheating part, the low temperature part and the high temperature part of the square arrangement increase the temperature, so the heat exchange efficiency of the GGH reheater can be improved. In addition, the efficiency of the collision between the mist scattered from the wet flue gas desulfurization device and the heat transfer tubes of the upstream package (the mist evaporation efficiency of the high-temperature preheating section) can be improved, and the influence of the mist on the heat transfer tubes of the low-temperature part and the high-temperature part can be suppressed. Adhesion can suppress the increase in pressure loss caused by long-term use.

However, in the GGH reheater (gas-to-gas heat exchanger) of Patent Document 1, three rows of heat transfer tube packs (upstream pack, midstream pack, and downstream pack) are arranged along the flow direction of exhaust gas. ), and set the heat transfer tube arrangement pattern of each row of heat transfer tube bundles to the same arrangement pattern (staggered arrangement in the upstream package, square arrangement in the middle stream and downstream package), so for example, it is desired to change the pattern of Patent Document 1 The structure is suitable for an existing gas-to-gas heat exchanger with two rows of heat transfer tubes bundled along the exhaust gas flow direction. In addition to the existing two rows of heat exchange bundles, a new one row of heat must be installed. To exchange packages, large-scale modifications are necessary.

Therefore, an object of the present invention is to provide a gas-to-gas heat exchanger that can suppress the increase in the number of rows of heat exchange packages along the flow direction of exhaust gas, and configure a desired heat transfer tube arrangement pattern in the gas flow path . [Technical means to solve the problem]

In order to achieve the above-mentioned object, the first aspect of the present invention is a gas-to-gas heat exchanger, which arranges a plurality of rows of heat exchange packages from the upstream side of the exhaust gas to the downstream side in a straight line, and the heat exchange bundles are arranged in a plurality of rows. In each package, a plurality of linear pipes are arranged to cross the flow direction of the exhaust gas, and the heat exchange package is formed by separating the plurality of linear pipes of the heat transfer tube from each other and arranging them in a block shape. The heat transfer tube group is composed. A plurality of heat exchange packages include a piping pattern mixed package in which the first arranging tube group and the second arranging tube group are arranged in the same package to form a heat transfer tube group. The piping pattern of the plurality of linear pipes of the orthogonal cross-section of the pipes that are substantially orthogonal to each other is the first arrangement, and the second arrangement of pipes is a plurality of linear pipes arranged on the downstream side of the first arrangement of pipes. The piping pattern of is the second arrangement different from the first arrangement.

In the above structure, the first arrangement tube group and the second arrangement tube group with different piping patterns are provided in one heat exchange package, so the increase in the number of rows of the heat exchange package along the exhaust gas flow direction can be suppressed. The desired heat transfer tube arrangement pattern is constructed in the gas flow path.

The second aspect of the present invention is on the downstream side of the heat recovery device that recovers heat from the exhaust gas, and on the downstream side of the desulfurization device that removes sulfur oxides in the exhaust gas by gas-liquid contact, as a re The first aspect of the gas-to-gas heat exchanger arranged by the heater includes a plurality of heat exchange packages, including a piping mode mixed package, and a downstream heat exchange package arranged on the downstream side of the piping mode mixed package. The first arrangement tube group is a staggered arrangement tube group in which a plurality of linear tube portions are arranged in a staggered pattern. The second arrangement tube group is a square arrangement tube group in which a plurality of linear tube portions are arranged in a square grid. In the staggered tube group, a heat medium flows in from the heat recovery device. The staggered tube group and the heat transfer tube group of the downstream heat exchange package are provided by the first connecting pipe in a way that the heat medium circulating in the staggered tube group circulates through the heat transfer tube group of the downstream heat exchange package. connect. The heat transfer tube group of the downstream heat exchange package and the square arrangement tube group are provided by the second connecting pipe in a way that the heat medium flowing through the heat transfer tube group of the downstream heat exchange package circulates through the square arrangement tube group. connect.

In the above structure, the staggered tube group, the square tube group, and the downstream heat exchange package (the heat transfer tube group that constitutes the downstream heat exchange package) function as a high-temperature preheating section, a low-temperature section, and a high-temperature section. Function, the introduced exhaust gas will rise in sequence through the staggered high-temperature preheating section, the square-arranged low-temperature section and the high-temperature section, so the heat exchange rate of the reheater (gas-to-gas heat exchanger) can be improved efficiency. In addition, it is possible to improve the efficiency of the conflict between the mist scattered from the desulfurization device and the linear tube parts of the staggered arrangement of the tube group (the mist evaporation efficiency of the high-temperature preheating part), and to suppress the adhesion of the mist in the heat transfer tube at the low-temperature part and the high-temperature part, It can suppress the increase in pressure loss caused by long-term use.

The third aspect of the present invention is that in the gas-to-gas heat exchanger of the second aspect, the linear tube portions of the staggered tube group are composed of bare tube parts of the bare tube specification, and the square tube group is arranged The linear tube part and the linear tube part of the downstream heat exchange package are composed of a fin tube part of the fin tube specification.

In the above structure, the straight tube section of the staggered tube group is constituted by the bare tube section of the bare tube specification, so the adhesion of mist to the heat transfer tube of the high temperature preheating section can be suppressed, and the pressure loss caused by long-term use can be suppressed. The rise. In addition, the linear tube portion of the square-arranged tube group and the linear tube portion of the downstream heat exchange package are composed of finned tube specifications, so the efficiency of heat exchange between the low temperature part and the high temperature part can be improved. .

In a fourth aspect of the present invention, in the gas-to-gas heat exchanger of the third aspect, the fin pitch of the fin tube portion of the linear tube portion of the square-arranged tube group is 5.0 mm or more and 10.0 mm or less. In addition, in the fifth aspect of the present invention, in the gas-to-gas heat exchanger of the third or fourth aspect, the fin pitch of the fin tube portion of the linear tube portion of the downstream heat exchange package is 5.0 mm above 10.0mm.

The above-mentioned structure can solve the problem of accumulation of dust over time between adjacent fin tube portions, and can stably operate the gas-to-gas heat exchanger.

The sixth aspect of the present invention is a gas-to-gas heat exchanger of any one of the second to fifth aspects, in which the staggered arrangement tube group is arranged so as to flow between the linear tube portions of the staggered arrangement tube group The flow velocity of the exhaust gas is 8m/s or more and 16m/s or less.

The above structure can improve the mist removal rate (removal rate of mist scattered from the desulfurization device) in the first arrangement tube group (staggered arrangement tube group) on the upstream side in the reheater, and improve the mist removal performance. Therefore, it is possible to reduce the corrosion of the second arrangement tube group on the downstream side or the linear tube part of the downstream heat exchange package (the fin tube part when the linear tube part is constituted by the fin tube part) (fog location). Caused by corrosion), the gas-to-gas heat exchanger can be used stably. [Effects of Invention]

According to the gas-to-gas heat exchanger of the present invention, it is possible to suppress an increase in the number of rows of heat exchange packages along the flow direction of exhaust gas, and to configure a desired heat transfer tube arrangement pattern in the gas flow path.

One embodiment of the present invention will be described with reference to the drawings. In the following description, the directions (sides) shown by arrows X, -X, Y, -Y, Z, and -Z in the figure are respectively designated as front (front), rear (rear), and right. Square (right side), left side (left side), above (upper side), and below (lower side).

As shown in Figure 1, the exhaust gas flow path of the exhaust gas treatment system (power plant) S of this embodiment is provided in line with: an air preheater (A/H) 3, which serves as a gas-to-gas heat GGH heat recovery device (GGH: Gas Gas Heater) as an example, dust collector (EP: Electrostatic Precipitator) 5, fan 6, wet flue gas desulfurization (FGD: Flue Gas Desulfurization) 7, as gas The GGH reheater 8 and the chimney 9 as an example of the gas heat exchanger, the exhaust from the boiler 1 circulates through the air preheater 3, the GGH heat recovery device 4, the dust collector 5, and the fan 6 in this order , The wet flue gas desulfurization device 7, and the GGH reheater 8 are discharged from the chimney 9. In this embodiment, although the present invention is applied to the GGH reheater 8, the present invention can also be applied to the GGH heat recovery unit 4. Furthermore, the present invention can also be applied to GGH of other systems. Moreover, a denitration device for removing nitrogen oxides in the exhaust gas may be installed between the boiler 1 and the air preheater 3.

In the air preheater 3, the exhaust gas and the combustion air for the boiler 1 exchange heat. In the GGH heat recovery unit 4, heat recovery from the exhaust gas is performed, and in the dust collector 5, most of the coal dust in the exhaust gas is removed. The fan 6 boosts the exhaust gas, and in the wet flue gas desulfurization device 7, the sulfur oxides and part of the coal dust in the exhaust gas are removed by gas-liquid contact. In the wet flue gas desulfurization device 7, the exhaust gas cooled to the temperature of the saturated gas is heated in the GGH reheater 8 using the heat recovered by the GGH heat recovery device 4 (heat exchange, reheating) After that, it is discharged from the chimney 9.

As shown in FIG. 2, in the exhaust treatment system S of the present embodiment, the heat transfer tube 11 of the GGH heat recovery device 4 and the heat transfer tube 12 of the GGH reheater 8 are connected by a connection pipe 13. The connection piping 13 has: the heat medium flow path from the GGH heat recovery unit 4 to the GGH reheater 8, which is the connection pipe 13A, and the heat medium flow path from the GGH reheater 8 to the GGH heat recovery unit 4, which is the connection pipe 13B. The connection pipe 13 is provided with a heat medium circulation pump 14 and becomes a system (heat medium circulation system) that circulates the heat medium by the heat medium circulation pump 14. In the heat medium circulation system, a heat medium tank 15 for absorbing the expansion of the heat medium in the system is provided. The connecting pipe 13A, which is the heat medium flow path from the GGH heat recovery unit 4 to the GGH reheater 8, is provided with heat medium heating that controls the temperature of the heat medium (controls it above a predetermined temperature) for stable operation under various conditions器16.

As shown in FIG. 3, the GGH heat recovery unit 4 and the GGH reheater 8 have a casing 31 as a housing. The housing 31 has a bottom plate (lower mask) 32, a back plate (rear mask) 33, and a top plate (upper mask) 34. At the front part of the housing 31, a packing room cover 35 extending in the up-and-down direction is supported. The inter-packing mask 35 extends in the up-down direction (vertical direction), and is arranged in plural at predetermined intervals in the left-right direction (exhaust gas flow direction). The area covered by the packing room mask 35 is a space accessible to the operator during maintenance or parts exchange.

Inside the housing 31, a plurality of heat exchange packages 41 are stored. The heat exchange package 41 is a structure of a heat transfer tube group formed by combining the heat transfer tubes 11 and 12 as a structural unit of the heat transfer tubes 11 and 12 through which a heat medium flows. Each heat exchange package 41 is composed of a heat transfer tube group in which a plurality of linear tube portions 45 of the heat transfer tubes 11 and 12 are separated from each other and arranged in a block shape. The heat exchange packages 41 in the housing 31 are arranged in a series from the upstream side of the exhaust gas to the downstream side, and in each of the heat exchange packages 41, a plurality of linear pipe portions 45 It is arranged to cross the flow direction of exhaust gas. In this embodiment, the exhaust gas flow direction is set to a substantially horizontal direction (the right direction in the figure), and the linear pipe portion 45 is substantially perpendicular to the exhaust gas flow direction in a substantially horizontal direction (the front-rear direction in the figure). Straight line extension.

Each heat exchange package 41 has a first head 42 and a second head 43. The first and second heads 42, 43 are formed in a columnar shape extending in the vertical direction. Each of the heads 42 and 43 is formed into a hollow inside and closed upper and lower ends, and a flowable space is formed inside. In addition, each of the heads 42 and 43 supports a mounting plate 44 protruding in the left-right direction.

Behind each of the heads 42, 43, the linear tube portions 45 of the heat transfer tubes 11, 12 extending rearward are supported. The heat transfer tubes 11 and 12 are formed by bending at the rear end or the front end of the linear tube portion 45 in the inside of the housing 31 and reciprocating in the front-rear direction several times. In addition, in each of the heads 42, 43, a plurality of heat transfer tubes 11, 12 are supported at intervals in the vertical direction. Both ends of the heat transfer tubes 11 and 12 are supported by the heads 42 and 43 and are configured to allow the heat medium to enter and exit the heat transfer tubes 11 and 12 from the heads 42 and 43.

The linear tube part 45 of each heat transfer tube 11 and 12 is the center part in the front-back direction, and is supported by the auxiliary member 47. The auxiliary member 47 is formed in a shape in which a plurality of holes through which the heat transfer tubes 11 and 12 pass are formed in the plate. Therefore, the heat transfer tubes 11 and 12 are not only supported by the heads 42 and 43 in a unilaterally held state, but are held by the heads 42 and 43 and the auxiliary member 47. In addition, although the figure shows a state in which one auxiliary member 47 is provided in the front-rear direction and the left-right direction, according to the length of the heat transfer tubes 11, 12, a plurality of auxiliary members 47 may be provided in the front-rear direction, or may be provided in the left-right direction. A plurality of auxiliary members 47.

The heads 42 and 43 have plug holes 48 at positions corresponding to the heat transfer tubes 11 and 12. The plug hole 48 is a hole penetrating in the front-rear direction, and the rear end is connected to the inlet or the outlet of the heat transfer tubes 11 and 12. In addition, the tip of the plug hole 48 is plugged by a plug (not shown) during normal use. When any one of the heat transfer tubes 11, 12 fails and the heat medium leaks out, remove the plug of the plug hole 48, and close the inlet or outlet of the heat transfer tubes 11, 12 through the plug hole 48 (as shown in the figure) Omit) to plug it, thereby preventing leakage of the heat medium.

Between the heads 42, 43, a shell 49 is detachably supported. The shell 49 has a height corresponding to the height of the heads 42 and 43 in the up and down direction. The shell 49 is detachably supported by the mounting plate 44 by bolts (not shown). In addition, the method of detachably fixing the shell 49 to the mounting plate 44 is not limited to bolts. The mounting shell 49 connects the heads 42, 43, and integrates the heads 42, 43 and the heat transfer tubes 11, 12 in a state of high rigidity, so as to prevent the leakage of exhaust gas from between the heads 42, 43. condition.

The heat exchange package 41 is configured to be housed in the housing 31 as a unit. In a state where the heat exchange package 41 is housed in the housing 31, the interior is surrounded by the bottom plate 32, the back plate 33, the top plate 34, the packing room cover 35, the heads 42, 43, and the shell 49. There is a gas flow path through which exhaust gas flows. In addition, the heat transfer tubes 11 and 12 are arranged in the gas flow path, and are configured to be able to exchange heat with the exhaust gas flowing in the gas flow path.

In each of the GGH heat recovery unit 4 and the GGH reheater 8 of the present embodiment, the heat exchange packs 41 are arranged in two rows along the flow direction of the exhaust gas, and the heat exchange packs 41 are overlapped in the vertical direction in each row. There are two layers, and four heat exchange packages 41 are provided. The upstream two layers of heat exchange packages 41 each constitute an upstream package (upstream heat exchange package) 41A, and the downstream two layers of heat exchange packages 41 each constitute a downstream package (downstream heat exchange package). Package) 41B. In this embodiment, in each row, the lower ends of the heads 42 and 43 of the upper heat exchange package 41 are directly stacked on the upper ends of the lower heat exchange package 41 and fixed with bolts (not shown). In the following description, the heat exchange packages 41 of the two layers on the upstream side are collectively referred to as the upstream package 41A, and the heat exchange packages 41 of the two layers on the downstream side are collectively referred to as the downstream package 41B. In addition, the number of rows of the heat exchange package 41 may be three or more, and the number of layers of the heat exchange package 41 of each row may be one layer (a single heat exchange package 41 constitutes one row) or three or more layers.

As shown in FIG. 2, the upstream side package 41A and the downstream side package 41B of the GGH heat recovery unit 4 are connected at each part by a connecting pipe 61, so that the heat medium can be connected to the upstream side package 41A and the downstream side. Move between side packs 41B. In addition, the GGH heat recovery device 4 of the present embodiment is configured to flow the heat medium from the downstream side package 41B to the upstream side package 41A. When the heat medium flows from the upstream side package 41A to the downstream side package 41B, the temperature difference between the heat medium and the exhaust gas becomes the largest at the upstream side package 41A, and at the downstream side package 41B, the upstream side package The temperature difference between the heat medium heated by the package 41A and the exhaust gas cooled by the heat exchange on the upstream side package 41A is reduced, and the efficiency of heat exchange is reduced. Therefore, in this embodiment, the heat medium is configured to It flows from the downstream side package 41B to the upstream side package 41A.

In this embodiment, the upstream side package 41A of the GGH reheater 8 is configured as a piping mode mixed package. The piping mode mixed package refers to a heat exchange package 41 in which the piping mode of the plurality of linear tube sections 45 is configured differently on the upstream side and the downstream side in the tube orthogonal cross section substantially orthogonal to the linear tube section 45. In the example of the upstream side package 41A shown in FIG. 4, among the linear pipe portions 45 arranged in ten rows in the gas flow direction, the two rows on the upstream side are set as a staggered arrangement of pipe groups ( The first arranging pipe group) 51 has eight rows on the downstream side as a square arranging pipe group (a second arranging pipe group having a different piping pattern from the first arranging pipe group) 52 arranged in a square grid. In this embodiment, the distance L1 between the linear tube portions 45 of the two adjacent rows of the staggered tube group 51, the straight lines of the two adjacent rows sandwiching the boundary between the staggered tube group 51 and the square-arranged tube group 52 The distance L2 between the rows of the tube-shaped tube portion 45 and the distance L3 between the linear tube portions 45 of two adjacent rows in the square-arranged tube group 52 are set to be substantially the same distance (L1=L2=L3).

The downstream side package 41B of the GGH reheater 8 of the present embodiment is configured as a piping mode non-mixed package (piping mode single package). The piping mode non-mixed package refers to the heat transfer tube package 41 that covers the entire area (all rows) from the upstream side to the downstream side and is set to the same piping mode (square arrangement in this embodiment). The upstream side package 41A and the downstream side package 41B of the GGH heat recovery unit 4 of this embodiment are the same as the downstream side package 41B of the GGH reheater 8. Column), a piping mode non-mixed package composed of the same piping mode (square arrangement in this embodiment).

In the square arrangement, the exhaust gas will contact the linear pipe 45 of the most upstream row among the plurality of rows, but on the downstream side, the linear pipe 45 of the second row and subsequent rows is the most upstream row with respect to the flow direction of the exhaust gas. Since the linear piping 45 is blocked, the contact with the exhaust gas will be reduced. Due to the reduced contact, the exhaust gas will flow easily. On the other hand, in the staggered arrangement, the linear pipes 45 in the second row and later (the second row in this embodiment) are difficult to be blocked by the linear pipes 45 in the front row (the first row in this embodiment). The air contact will increase, but it will relatively become the resistance of the exhaust gas. In addition, since it becomes resistance to the exhaust gas, the exhaust gas is rectified.

In the GGH reheater 8 of the present embodiment, the heat medium flowing out of the GGH heat recovery device 4 flows through the connecting pipe 13A and flows into the heat medium inlet of the staggered pipe group 51. The heat medium outlet of the staggered tube group 51 and the heat medium inlet of the heat transfer tube group of the downstream side bundle 41B are configured by the heat medium circulating in the staggered tube group 51 flowing through the heat transfer tube group of the downstream side bundle 41B In this way, it is connected by the first connecting pipe 62. The heat medium outlet of the heat transfer tube group of the downstream side bundle 41B and the heat medium inlet of the square arrangement tube group 52 are the heat medium that circulates through the heat transfer tube group of the downstream side bundle 41B circulates through the square arrangement tube group 52 In this way, it is connected by the second connecting pipe 63. The heat medium from the downstream side package 41B flows into the heat medium inlet of the square-arranged tube group 52. The heat medium flowing through the square arrangement tube group 52 and flowing out from the heat medium outlet of the square arrangement tube group 52 circulates through the connection pipe 13B and returns to the GGH heat recovery unit 4.

As described above, the staggered tube group 51, the square tube group 52, and the downstream side bundle 41B (the heat transfer tube group constituting the downstream side bundle 41B) function as a high-temperature preheating section, a low-temperature section, and a high-temperature section. Function, the introduced exhaust gas will be sequentially heated by the staggered high-temperature preheating section, the square-arranged low-temperature section and the high-temperature section. The heat medium is first introduced to the upstream staggered tube group 51, so that the heat medium flows in the hottest state in the staggered tube group 51, and the mist from the wet flue gas desulfurization device 7 easily evaporates quickly. In addition, the heat medium is caused to flow from the downstream package 41B on the downstream side to the square-arranged tube group 52 in the middle stream, thereby making the temperature of the heat medium higher downstream than in the middle stream. If the temperature of the heat medium is lower in the downstream than in the middle stream, after heating the exhaust gas in the high temperature middle stream, it passes through the low temperature downstream, making it difficult for the exhaust gas to warm downstream, and the efficiency of heat exchange is low. In this regard, as in the present embodiment, when the temperature of the heat medium is higher in the downstream than in the middle stream, the exhaust gas is heated in order from the low temperature in the middle stream to the high temperature in the downstream, so that the efficiency of heat exchange is improved.

In the GGH heat recovery device 4 of the present embodiment, both the upstream side bundle 41A and the downstream side bundle 41B are composed of fin tube portions of a fin tube specification in which a large number of folded fins are provided. 11的linear pipe section 45. By using the finned tube section, the contact area with the exhaust gas is larger compared with the case where the bare tube section without fins is formed, and the efficiency of heat exchange is improved.

In the GGH reheater 8 of this embodiment, the straight tube portion 45 of the staggered arrangement tube group 51 is constituted by a bare tube portion, and the straight tube portion 45 and the downstream bundle of the square arrangement tube group 52 are constituted by a finned tube portion. The linear tube portion 45 of the bag 41B. If the linear tube section 45 of the staggered tube group 51 is composed of finned tube sections, the mist from the wet flue gas desulfurization device 7 will adhere and easily corrode. In this embodiment, the bare tube section is constituted. The linear tube portions 45 of the staggered arrangement of the tube group 51 are more difficult to corrode than the case where the tube portion is composed of fins.

The GGH heat recovery device 4 uses a square arrangement to reduce ash wear (the phenomenon of rubbing and grinding the surface of the heat transfer tube with coal ash in the exhaust gas). In addition, the GGH heat recovery device 4 is configured with finned tube portions to ensure contact with exhaust gas. In addition, the staggered arrangement of the tube group 51 of the GGH reheater 8 allows the mist from the wet flue gas desulfurization device 7 to easily flow in. The staggered arrangement increases the probability of contact with the mist and facilitates the removal of the mist.

In addition, in order to alleviate the corrosive environment of the fin tube section of the GGH reheater 8 for stable operation, the upstream side of the fin tube section, that is, the mist removal efficiency of the staggered tube group 51 is preferably 60% or more. , The staggered arrangement of pipes is arranged such that the flow velocity of the gas flowing between the linear pipe portions (the bare pipe portion in this embodiment) 45 of the staggered arrangement of pipes 51 is in the range of 8m/s to 16m/s The straight tube portion (bare tube portion) 45 of 51 is preferred.

In addition, the fin pitch of the fin tube part of the GGH reheater 8 (the fin tube part of at least one of the square arrangement tube group 52 and the downstream package 41B) is set to 5.0 mm to 10.0 mm, thereby eliminating The problem of clogging dust over time by the fin tube can be used more stably.

As described above, according to the present embodiment, in the GGH reheater 8, the first arrangement tube group (staggered arrangement tube group) with different piping patterns is provided in one heat exchange package 41 (upstream side package 41A) 51 and the second arrangement tube group (square arrangement tube group) 52, it is possible to suppress the increase in the number of rows of the heat exchange pack 41 along the flow direction of the exhaust gas, and to configure the desired heat transfer tube arrangement pattern in the gas Flow path.

In addition, the staggered arrangement tube group 51, the square arrangement tube group 52, and the downstream side package 41B (the heat transfer tube group constituting the downstream side package 41B) function as a high-temperature preheating section, a low-temperature section, and a high-temperature section, respectively. The introduced exhaust gas passes through the staggered high-temperature preheating section, the square-arranged low-temperature section, and the high-temperature section in order to increase the temperature. Therefore, the heat exchange efficiency of the GGH reheater 8 can be improved. In addition, it is possible to improve the efficiency of the collision between the mist scattered from the wet flue gas desulfurization device 7 and the linear tube section 45 of the staggered arrangement of the tube group 51 (the mist evaporation efficiency of the high-temperature preheating section), and suppress the influence of the mist on the low-temperature and high-temperature sections. The attachment of the heat transfer tube 12 can suppress the increase in pressure loss caused by long-term use.

In addition, the linear tube portion 45 of the staggered tube group 51 is constituted by a bare tube portion, so the adhesion of mist to the heat transfer tube 12 of the high-temperature preheating portion can be suppressed, and the increase in pressure loss due to long-term use can be suppressed. In addition, the linear tube portion 45 of the square-arranged tube group 52 and the linear tube portion 45 of the downstream side package 41B are constituted by fin tube portions, so that the efficiency of heat exchange between the low temperature portion and the high temperature portion can be improved.

In addition, by optimizing the flow rate of the gas flowing in the linear tube portion (the bare tube portion in this embodiment) 45 of the staggered tube group 51 or the fin pitch of the fin tube portion, the fins are prevented Corrosion of the tube section or blockage caused by dust, etc., can be used stably.

In addition, the present invention is not limited to the above-mentioned embodiments and modifications explained as an example. In addition to the above-mentioned embodiments, etc., as long as they do not deviate from the scope of the technical thinking of the present invention, they can be carried out in accordance with design, etc. Various changes.

For example, as shown in FIG. 5, the present invention is applied to a smoke treatment system S that divides the GGH heat recovery device 4 and the GGH reheater 8 into a plurality of systems (two systems in the example of FIG. 5), so that a plurality of GGH At least one of the heat recovery unit 4 or at least one of the plurality of GGH reheaters 8 may be configured as in the above-mentioned embodiment.

In addition, in the above-mentioned embodiment, the exhaust gas flow direction is set to a substantially horizontal direction, and the direction in which the linear tube portion 45 extends (extension direction) is set to a substantially horizontal direction that is substantially orthogonal to the exhaust gas flow direction. The air flow direction and the extending direction of the linear tube portion 45 are not limited to those described above, and they are set to other directions (the exhaust gas flow direction is set to a substantially horizontal direction, and the extending direction of the linear tube portion 45 is set to the vertical direction ( Roughly vertical direction)) can also be used.

1: boiler 3: Air preheater (A/H) 4: GGH heat recovery device (gas to gas heat exchanger) 5: Dust collection device (EP) 6: Fan 7: Wet flue gas desulfurization device 8: GGH reheater (gas to gas heat exchanger) 9: Chimney 11, 12: Heat transfer tube 13, 13A, 13B: Contact piping 31: Shell 41: heat exchange packing 41A: Upstream side packing (upstream side heat exchange packing, piping mode mixed packing) 41B: Downstream side package (downstream side heat exchange package) 42: 1st head 43: 2nd head 45: Straight tube 49: Shell 51: Staggered arrangement of pipe groups (the first arrangement of pipe groups) 52: Square configuration tube group (2nd configuration tube group) 61: Connecting piping S: Smoke exhaust treatment system

[Fig. 1] A diagram schematically showing a configuration example of an exhaust gas treatment system equipped with a gas-to-gas heat exchanger according to an embodiment of the present invention. [Fig. 2] A diagram schematically showing the flow of the heat medium in the exhaust gas treatment system of Fig. 1. [Fig. [Fig. 3] A perspective view schematically showing the schematic structure of the GGH reheater in Fig. 1. [Fig. [Fig. 4] A cross-sectional view showing the piping mode of the linear pipe portion of the piping mode mixed package of Fig. 3. [Fig. [Fig. 5] A diagram schematically showing a configuration example of a smoke exhaust treatment system in which the GGH heat recovery device and the GGH reheater are divided into two systems.

12: Heat transfer tube

41: heat exchange packing

41A: Upstream side packing (upstream side heat exchange packing, piping mode mixed packing)

45: Straight tube

51: Staggered arrangement of pipe groups (the first arrangement of pipe groups)

52: Square configuration tube group (2nd configuration tube group)

Claims (6)

A gas-to-gas heat exchanger, It arranges a plurality of rows of heat exchange packages from the upstream side to the downstream side of the exhaust gas in a straight line, and in each of the plurality of rows of heat exchange packages, a plurality of linear pipes are arranged to cross the flow direction of the exhaust gas. The heat exchange package is composed of a heat transfer tube group in which the plurality of linear tube portions of the heat transfer tube are separated from each other and arranged in a block shape, and is characterized by: The plurality of heat exchange packages include a piping pattern mixed package in which the first arranging tube group and the second arranging tube group are arranged in the same package to form the heat transfer tube group, and the first arranging tube group is combined with The piping pattern of the plurality of linear pipes in the orthogonal cross-section of the linear pipe portion is the first arrangement, and the second arrangement pipe group is the aforementioned first arrangement pipe group provided on the downstream side of the first arrangement pipe group. The piping pattern of the plurality of linear pipe portions becomes a second arrangement different from the aforementioned first arrangement. The gas-to-gas heat exchanger according to claim 1, wherein it is on the downstream side of a heat recovery device that recovers heat from exhaust gas, and is used to remove sulfur oxides in exhaust gas by gas-liquid contact The downstream side of the desulfurization device is configured as a reheater, The plurality of heat exchange packages include the piping mode mixed package and the downstream heat exchange package arranged on the downstream side of the piping mode mixed package, The first arrangement tube group is a staggered arrangement tube group in which the plurality of linear tube portions are arranged in a staggered pattern, The second arrangement tube group is a square arrangement tube group in which the plurality of linear tube portions are arranged in a square lattice shape, In the aforementioned staggered tube group, a heat medium flows in from the aforementioned heat recovery device, The cross-arranged tube group and the heat transfer tube group of the downstream heat exchange package are in a manner in which the heat medium circulating in the cross-arranged tube group flows through the heat transfer tube group of the downstream heat exchange package. Is connected by the first connecting pipe, The heat transfer tube group and the square arrangement tube group of the downstream heat exchange package are configured such that the heat medium flowing through the heat transfer tube group of the downstream heat exchange package circulates through the square arrangement tube group. It is connected by the second connecting pipe. The gas-to-gas heat exchanger described in claim 2, wherein: The linear tube part of the staggered tube group is composed of a bare tube part of a bare tube specification, The linear tube portion of the square-arranged tube group and the linear tube portion of the downstream heat exchange package are constituted by fin tube portions of a fin tube specification. The gas-to-gas heat exchanger described in claim 3, wherein: The fin pitch of the fin tube portion of the linear tube portion of the square arrangement tube group is set to 5.0 mm to 10.0 mm. The gas-to-gas heat exchanger as described in claim 3 or claim 4, wherein: The fin pitch of the fin tube part of the linear tube part of the downstream heat exchange package is set to 5.0 mm to 10.0 mm. The gas-to-gas heat exchanger according to any one of claim 2 to claim 5, wherein: The staggered pipe group is arranged so that the flow velocity of the exhaust gas flowing between the linear pipe portions of the staggered pipe group becomes 8m/s to 16m/s.

Images