Desulfurization device

Abstract

To inhibit a cleaning liquid of a heat exchanger from being mixed to an absorbing liquid for desulfurization.SOLUTION: A desulfurization unit (1) includes: a heat exchanger (21) which recovers heat from exhaust gas of a passage upstream part (7) and heats the exhaust gas at the downstream side of an injector (11) with respect to an exhaust gas flow direction with the recovered heat; a cleaner (26) which is disposed at the passage upstream part (7) and injects the cleaning liquid to the heat exchanger (21); a discharge part (28) which is provided at a bottom part of the passage upstream part (7) and discharges the cleaning liquid; and a restriction member (31) which is disposed at the downstream side of the discharge part (28) and the upstream side of a border (8a) between an inflow part (8) and a passage downstream part (4) with respect to the gas flow direction and restricts inflow of the cleaning liquid into the passage downstream part (4).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a desulfurization apparatus for removing sulfur content from exhaust gas, and more particularly to a desulfurization apparatus having a heat exchanger for recovering heat from untreated exhaust gas and heating the treated exhaust gas. [Background technology]

[0002] In desulfurization equipment that removes sulfur from flue gas (exhaust gas) from boilers, etc., wet desulfurization equipment is known in which the flue gas is brought into contact with an absorbing liquid in the absorption tower of the desulfurization equipment. In wet desulfurization equipment, the flue gas at the outlet of the absorption tower becomes water-saturated gas, which causes corrosion due to SO3 mist and purple smoke at the chimney outlet. To prevent this, it is common to install a gas reheating device at the outlet of the absorption tower to increase the temperature of the flue gas and discharge it from the chimney. The following Patent Documents 1 and 2 disclose known techniques for heating exhaust gas.

[0003] Patent Document 1 (JP 2009-95697 A) describes a technology in which a heat storage body (1) rotating about a rotating shaft (9) passes through a section through which untreated gas passes and a section through which treated gas passes in turn, thereby recovering heat from the untreated gas and heating (reheating) the treated gas with the recovered heat. In the technology described in Patent Document 1, in the gas flow path through which untreated gas passes, washing liquid is sprayed from above and below the heat storage body (1) using water washing nozzles (8, 10) to wash it with water.

[0004] Patent Document 2 (China Patent Publication No. 103063082: CN103063082A) describes a technology for cleaning a rotary type GGH (gas-gas heater, heat exchanger) similar to that described in Patent Document 1 by spraying high-pressure water from a high-pressure shower (13) or by spraying a chemical solution from a jet (42). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-95697 A ("0016"-"0019", Figs. 1 and 2) [Patent Document 2] China Patent Publication No. 103063082 (Fig. 1) Summary of the Invention [Problem to be solved by the invention]

[0006] Exhaust gas from coal-fired power plants contains particles such as coal combustion ash, and these particles adhere to the heat exchanger elements (heat transfer tubes) during heat recovery. Therefore, as in the techniques described in Patent Documents 1 and 2, it is common practice to wash the parts through which untreated gas flows with a washing liquid. In particular, in a rotating type (Ljungstrom type) GGH as described in Patent Documents 1 and 2, the portion to which coal combustion ash adheres during heat recovery enters the treated gas side as the GGH rotates. At this time, the treated gas side may contain a mist of desulfurization absorbing liquid, and the mist causes particles such as coal combustion ash adhering to the GGH to solidify, which tends to increase pressure loss.

[0007] FIG. 4 is a schematic explanatory diagram of a desulfurization device equipped with a heat exchanger according to the prior art. In Fig. 4, in a desulfurization device 01 as disclosed in Patent Documents 1 and 2, a rotary type GGH 02 passes through an upstream section 03, through which untreated gas flows, and a downstream section 04 in that order. A washer 06 for washing the GGH 02 is disposed in the upstream section 03. In addition, a storage section 07 for storing an absorbing liquid at the bottom is disposed in the downstream section 04, and an injector 08 for injecting the absorbing liquid below the GGH 02 is disposed. 4, when the GGH02 is washed with a washer 06 as in Patent Documents 1 and 2, the washing liquid flowing down from the GGH02 contains K (potassium), Na (sodium), Mg (magnesium), and F (fluorine) contained in the coal ash. If this washing liquid flows into the storage section 07 and gets mixed into the absorption liquid for desulfurization, the concentration and pH of the absorption liquid may change, which may lead to a decrease in desulfurization performance.

[0008] An object of the present invention is to prevent a cleaning liquid for a heat exchanger from being mixed into an absorption liquid for desulfurization. [Means for solving the problem]

[0009] The above object of the present invention can be achieved by adopting the following configuration. The desulfurization device of the invention described in claim 1 comprises: an exhaust gas flow path including: a downstream flow path portion extending upward from a storage portion in which an absorbing liquid that absorbs sulfur content in the exhaust gas is stored; an inflow portion connected to the downstream flow path portion above the storage portion and into which the exhaust gas flows; and an upstream flow path portion connected to the upstream side of the inflow portion; an injector that injects the absorbing liquid into the exhaust gas downstream of the flow path; a heat exchanger that recovers heat from the exhaust gas in the upstream portion of the flow passage and heats the exhaust gas downstream of the injector with the recovered heat; a cleaning device disposed upstream of the flow path and configured to inject a cleaning liquid onto the heat exchanger; a discharge part provided at a bottom of the upstream part of the flow path and configured to discharge a cleaning liquid; a restricting member that is disposed downstream of the exhaust portion and upstream of a boundary between the inlet portion and the downstream portion of the flow path with respect to a gas flow direction, the restricting member restricting an inflow of the cleaning liquid into the downstream portion of the flow path; The present invention is characterized by comprising:

[0010] The invention described in claim 2 is the desulfurization apparatus described in claim 1, a return portion formed at an upper end portion of the regulating member in the gravity direction and inclined with respect to the gravity direction; The present invention is characterized by comprising:

[0011] The invention described in claim 3 is the desulfurization apparatus described in claim 2, the return portion inclined toward the downstream side in the gas flow direction as it goes upward in the gravity direction; The present invention is characterized by comprising:

[0012] The invention described in claim 4 is a desulfurization apparatus according to any one of claims 1 to 3, the regulating member capable of appearing and disappearing from a bottom surface of the exhaust gas flow passage; The present invention is characterized by comprising:

[0013] The invention described in claim 5 is the desulfurization apparatus described in claim 4, the regulating member protruding from a bottom surface of the exhaust gas flow passage when a cleaning operation is performed by spraying a cleaning liquid by the cleaning machine, and sinking into the bottom surface of the exhaust gas flow passage when the cleaning operation is completed; The present invention is characterized by comprising:

[0014] The invention described in claim 6 is a desulfurization apparatus according to any one of claims 1 to 5, the heat exchanger configured to be capable of storing heat and to be rotatable about a rotation axis, the heat exchanger passing through an interior of the upstream portion of the flow path and an interior of the downstream portion of the flow path in sequence; The present invention is characterized by comprising:

[0015] The invention described in claim 7 is a desulfurization apparatus according to any one of claims 1 to 6, a control unit that controls a timing of spraying the cleaner based on a pressure difference between an upstream side and a downstream side in a flow direction of the exhaust gas of the heat exchanger in the upstream portion of the flow passage; The present invention is characterized by comprising:

[0016] The invention described in claim 8 is a desulfurization apparatus according to any one of claims 1 to 7, a circulation unit that circulates the cleaning liquid discharged from the discharge unit to the cleaning machine; The present invention is characterized by comprising:

[0017] The invention described in claim 9 is the desulfurization apparatus described in claim 8, a control unit that determines whether or not to circulate the cleaning liquid through the cleaning machine based on a pH value of the cleaning liquid discharged from the discharge unit; The present invention is characterized by comprising:

[0018] The invention described in claim 10 is a desulfurization apparatus according to any one of claims 1 to 9, a water sealing member provided in the discharge portion and sealing an inlet side of the cleaning liquid; The present invention is characterized by comprising:

[0019] The invention described in claim 11 is the desulfurization apparatus described in claim 10, The water sealing member is constituted by a damper that closes the discharge portion; The present invention is characterized by comprising: Effect of the Invention

[0020] According to the invention recited in claim 1, it is possible to suppress the washing liquid for the heat exchanger from being mixed into the absorbing liquid for desulfurization, compared to a case in which no restricting member is provided. According to the invention as recited in claim 2, in addition to the effect of the invention as recited in claim 1, turbulence in the gas flow can be suppressed compared to a case in which there is no return portion. According to the invention as recited in claim 3, in addition to the effect of the invention as recited in claim 2, it is possible to reduce the generation of vortexes in the gas flow downstream of the return portion. According to the invention as set forth in claim 4, in addition to the effect of the invention as set forth in any one of claims 1 to 3, the restricting member can be protruded when in use and can be recessed when not in use.

[0021] According to the invention as set forth in claim 5, in addition to the effect of the invention as set forth in claim 4, it is possible to prevent the regulating member from disturbing the flow of exhaust gas when cleaning is not being performed. According to the invention recited in claim 6, in addition to the effects of the invention recited in any one of claims 1 to 5, it is possible to prevent the cleaning liquid used for cleaning the rotary heat exchanger from being mixed into the absorption liquid for desulfurization. According to the seventh aspect of the present invention, in addition to the effect of any one of the first to sixth aspects of the present invention, it is possible to automatically determine the time to clean the heat exchanger based on the pressure difference. According to the invention as set forth in claim 8, in addition to the effects of the invention as set forth in any one of claims 1 to 7, it is possible to reduce the environmental load and costs compared to a case in which the cleaning liquid is not circulated.

[0022] According to the invention recited in claim 9, in addition to the effect of the invention recited in claim 8, it is possible to prevent the cleaning liquid from being circulated when it is inappropriate to do so based on the pH. According to the invention as set forth in claim 10, in addition to the effect of the invention as set forth in any one of claims 1 to 9, the exhaust part can be water-sealed, and gas leakage through the exhaust part can be prevented. According to the eleventh aspect of the invention, in addition to the effect of the tenth aspect of the invention, water can be sealed by the damper. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic explanatory diagram of a desulfurization apparatus according to one embodiment of the present invention. [Diagram 2] 2A and 2B are explanatory diagrams of a modification of the first embodiment, where FIG. 2A is an explanatory diagram of a first modification of the first embodiment, and FIG. 2B is an explanatory diagram of a second modification of the first embodiment. [Diagram 3] FIG. 3 is an explanatory diagram of a desulfurization device according to a second embodiment of the present invention. [Figure 4] FIG. 4 is a schematic explanatory diagram of a desulfurization device equipped with a heat exchanger according to the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Next, examples of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following examples. In the following description using the drawings, illustrations of components other than those necessary for the description are omitted as appropriate to facilitate understanding. EXAMPLES

[0025] FIG. 1 is a schematic explanatory diagram of a desulfurization apparatus according to one embodiment of the present invention. In Fig. 1, a desulfurization apparatus 1 according to a first embodiment of the present invention has an absorption tower 2. Inside the absorption tower 2, a storage section 3 as an example of a storage section for an absorption liquid is formed at the bottom. The storage section 3 stores an absorption liquid (absorption liquid slurry). In addition, a flow path downstream section 4 extends upward from the storage section 3, through which exhaust gas from a boiler (not shown) to which the desulfurization apparatus 1 is connected passes. A duct 6 is disposed in parallel to the downstream flow path portion 4. An upstream flow path portion 7 through which exhaust gas passes is formed inside the duct 6. One end (upstream end) of an inlet portion 8 extending toward the absorption tower 2 is connected to a lower end of the upstream flow path portion 7. The other end (downstream end) of the inlet portion 8 is connected to a lower portion of the downstream flow path portion 4 and above the storage unit 3. The downstream flow passage portion 4, the upstream flow passage portion 7, the inlet portion 8, etc. constitute an exhaust gas flow passage 9 of the first embodiment.

[0026] In the upstream part 7 of the flow path, an absorbent sprayer 11 as an example of an injector is disposed above the boundary (connection position) with the inlet part 8. The absorbent sprayer 11 injects the absorbent slurry from the storage part 3 sent by the absorbent slurry pump 12 toward the flue gas passing through the upstream part 7 of the flow path, thereby desulfurizing the flue gas. A demister 13, which is an example of a liquid recovery machine, is disposed above the absorbing liquid sprayer 11. The demister 13 recovers the absorbing liquid in droplets or mist form sprayed from the absorbing liquid sprayer 11.

[0027] A GGH 21 as an example of a heat exchanger is disposed above the demister 13. The GGH 21 of the first embodiment has a heat storage body 22 as an example of a heat exchanger body. The heat storage body 22 is formed in a disk shape. The heat storage body 22 is supported rotatably about a rotating shaft 23 disposed between the upstream flow passage portion 7 and the downstream flow passage portion 4, and is rotated and driven by a motor 24. Therefore, a part (22a) of the heat storage body 22 enters the upstream flow passage portion 7, and another part (22b) enters the downstream flow passage portion 4. Then, the part (22a) of the heat storage body 22 that has entered the upstream flow passage portion 7 recovers heat from the exhaust gas, and when the part (22a) enters the downstream flow passage portion 4 as the heat storage body 22 rotates, the exhaust gas passing through the downstream flow passage portion 4 is reheated. Therefore, the GGH 21 in the first embodiment is configured by a conventionally known rotation type (Ljungstrom type) GGH.

[0028] In the upstream part 7 of the flow path, a cleaning spray 26 as an example of a cleaning machine is disposed above the heat storage body 22 (22a). The cleaning spray 26 sprays cleaning liquid supplied from a cleaning water pipe 27 toward the heat storage body 22 to clean it. In addition, when the cleaning liquid is sprayed by the cleaning spray 26, the heat storage body 22 rotates one or more times, so that the cleaning liquid can be sprayed over the entire heat storage body 22. A cleaning liquid drain pipe 28, which is an example of a drain portion, is connected to the bottom 7a of the flow path upstream portion 7. A cleaning water pit 29, which is an example of a storage portion for cleaning liquid, is disposed at the lower end of the cleaning liquid drain pipe 28. The cleaning liquid accumulated in the cleaning water pit 29 is drained when the amount thereof reaches or exceeds a predetermined amount.

[0029] A dam plate 31, as an example of a regulating member, is arranged downstream of the cleaning liquid drain pipe 28 in the flow direction of the exhaust gas and upstream of the boundary position 8a between the inlet section 8 and the downstream section 4 of the flow path, i.e., between the cleaning liquid drain pipe 28 and the storage section 3. The blocking plate 31 in the first embodiment is formed in a plate shape standing upward from the bottom surface near the upstream end of the inflow section 8. The blocking plate 31 is formed with a height and width capable of preventing (restricting) the liquid on the cleaning liquid drain pipe 28 side from flowing into the storage section 3 side. The height and width can be changed as desired according to the design and specifications such as the spray amount per unit time of the cleaning liquid used and the drainage capacity of the cleaning liquid drain pipe 28.

[0030] (Function of Example 1) In the desulfurization device 1 of the first embodiment having the above-mentioned configuration, coal combustion ash and the like adhere to the heat storage body 22 over time in the upstream part 7 of the flow path through which untreated exhaust gas passes before the injection of the absorption liquid slurry. In addition, as the heat storage body 22 rotates, the coal combustion ash and the like may adhere to the heat storage body 22 due to contact between the mist-like absorption liquid that has not been completely collected by the demister 13 and the coal combustion ash and the like in the downstream part 4 of the flow path. To cope with this, a cleaning liquid is sprayed from the cleaning spray 26 during regular maintenance or the like to clean the heat storage body 22. The cleaning liquid sprayed to the heat storage body 22 falls down the upstream part 7 of the flow path and is drained from the cleaning liquid drain pipe 28 at the bottom.

[0031] Here, in the conventional configuration not having the blocking plate 31, there was a risk that a portion of the cleaning liquid before flowing into the cleaning liquid drain pipe 28 would flow into the storage section 3 for the absorbent slurry, which could result in a decrease in the desulfurization performance of the absorbent slurry. In contrast, in the desulfurization apparatus 1 of the first embodiment, a blocking plate 31 is disposed between the cleaning liquid drain pipe 28 and the storage unit 3. Therefore, even if the cleaning liquid before flowing into the cleaning liquid drain pipe 28 attempts to move toward the storage unit 3, it is blocked by the blocking plate 31. This prevents the cleaning liquid from flowing into and being mixed into the storage unit 3. This prevents the desulfurization performance of the absorption liquid slurry from being reduced by the cleaning liquid.

[0032] (Modification of Example 1) 2A and 2B are explanatory diagrams of a modification of the first embodiment, where FIG. 2A is an explanatory diagram of a first modification of the first embodiment, and FIG. 2B is an explanatory diagram of a second modification of the first embodiment. In the first embodiment, the blocking plate 31 is exemplified as a plate-like structure rising upward from the bottom surface of the inlet portion 8, but is not limited thereto. For example, as shown in Figs. 2(A) and (B), the upper end of the blocking plate 31', 31" may be provided with return portions 31a', 31a" that are inclined in the up-down direction. As shown in Fig. 2(A), the return portion 31a' may be inclined toward the upstream side of the gas flow direction as it goes upward, and as shown in Fig. 2(B), the return portion 31a" may be inclined toward the downstream side of the gas flow direction as it goes upward. By providing the return portions 31a', 31a", it is possible to suppress turbulence of the gas flow at the blocking plate 31, i.e., the flow path resistance of the blocking plate 31. Which of the return portions 31a', 31a" in Figures 2(A) and (B) has a greater effect in suppressing flow path resistance varies depending on the flow path conditions, such as the flow velocity and the shape of the upstream flow path portion 7 (straight or curved, etc.) and the shape of the inlet portion 8 (horizontal or inclined to the horizontal, etc.), and can be arbitrarily changed depending on the design, etc. When the upstream flow path portion 7 is straight and the inlet portion 8 is horizontal, as in Example 1, the configuration shown in Figure 2(B) is preferable because it is less likely to cause eddies in the flow of exhaust gas downstream of the upper end of the blocking plate 31. EXAMPLES

[0033] FIG. 3 is an explanatory diagram of a desulfurization device according to a second embodiment of the present invention. Next, a second embodiment of the present invention will be described. In the description of the second embodiment, components corresponding to those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted. This embodiment 2 differs from the above-mentioned embodiment 1 in the following points, but is otherwise configured similarly to the above-mentioned embodiment 1.

[0034] 3, in the desulfurization apparatus 1 of the second embodiment, the damming plate 31 is configured to be capable of protruding and retracting from the bottom surface 8b of the inlet section 8. The damming plate 31 of the first embodiment is configured to be movable between a protruding position (damming position, see the solid line in FIG. 3) protruding from the bottom surface 8b and a recessed position (standby position, see the dashed line in FIG. 3) recessed from the bottom surface 8b. The protruding and retracting of the damming plate 31 of the second embodiment is controlled by a calculator 41 as an example of a control section. In the desulfurization device 1 of the second embodiment, pressure gauges SN1 and SN2 are disposed above and below the heat storage body 22 (22a), respectively, in the upstream portion 7 of the flow path. Values ​​measured by the pressure gauges SN1 and SN2 are input to a calculator 41. In the second embodiment, as an example, a differential pressure Δp between the pressures measured by the pressure gauges SN1 and SN2 is input to the calculator 41.

[0035] A damper 42, which is an example of a water sealing member, is disposed in the cleaning liquid discharge pipe 28 of the embodiment 2. The damper 42 opens / closes the cleaning liquid discharge pipe 28 to drain / stop draining the cleaning liquid. The opening and closing of the damper 42 in the second embodiment is controlled by a calculator 41. Although the damper 42 is exemplified as the water sealing member in the second embodiment, the water sealing member is not limited to this. For example, a valve (on-off valve) can also be used. 3, a pH meter SN3 for measuring the pH of the cleaning liquid and a liquid level meter SN4 for measuring the amount (water level) of the cleaning liquid are installed in the cleaning water pit 29 of Example 2. A drain pipe 46 for draining water from the cleaning water pit 29 and a circulation pipe 47 for circulating the cleaning water in the cleaning water pit 29 are connected to the cleaning water pit 29. The drain pipe 46 is opened and closed by a drain valve 46a, and drainage / stopping of water through the drain pipe 46 is performed. The drain valve 46a is controlled by a calculator 41.

[0036] The other end of the circulation pipe 47 joins with the cleaning water pipe 27. A cleaning liquid pump 48 for transporting the cleaning liquid is installed in the circulation pipe 47. The circulation pipe 47 and the cleaning liquid pump 48 constitute the circulation units 47, 48 of the second embodiment. Therefore, when the cleaning liquid pump 48 operates, the cleaning liquid in the cleaning water pit 29 is sent to the cleaning spray 26 and sprayed to the GGH 21. When the cleaning liquid in the cleaning water pit 29 is not used, the cleaning water valve 49 of the cleaning water pipe 27 is opened to supply new cleaning liquid. The cleaning liquid pump 48 and the cleaning water valve 49 of the second embodiment are controlled by the calculator 41.

[0037] (Explanation of the control unit (arithmetic unit 41) of the second embodiment) The calculator 41 of the desulfurization device 1 of the second embodiment has an input / output interface I / O for inputting and outputting signals from and to the outside. The calculator 41 also has a ROM (read-only memory) in which programs and information for performing necessary processing are stored. The calculator 41 also has a RAM (random access memory) for temporarily storing necessary data. The calculator 41 also has a CPU (central processing unit) for performing processing according to the programs stored in the ROM or the like. Therefore, the calculator 41 of the first embodiment is composed of an information processing device, a so-called computer device. Therefore, the calculator 41 can realize various functions by executing programs stored in the ROM or the like.

[0038] The calculator 41 controls the blocking plate 31, the damper 42, the drain valve 46a, the cleaning liquid pump 48, the cleaning water valve 49, etc., in response to input signals from the pressure gauges SN1 and SN2, the pH meter SN3, the liquid level meter SN4, etc. When the pressure difference ΔP between the pressure gauges SN1 and SN2 reaches a predetermined threshold, the calculator 41 of the second embodiment determines that coal combustion ash and the like has accumulated in the heat storage body 22, making it difficult for the exhaust gas to flow, and determines that it is time to clean the GGH 21. When the calculator 41 determines that it is time to clean the GGH 21, it notifies the operator of this by a notification method such as image display or voice guidance. When the operator receives the notification, he or she will stop the boiler according to the operating status of the boiler and start the cleaning work.

[0039] The calculator 41 of the second embodiment moves the blocking plate 31 from the recessed position to the protruding position when the cleaning work of the GGH 21 is started. When the cleaning is completed, the calculator 41 moves the blocking plate 31 from the protruding position to the recessed position. Moreover, the computing unit 41 of the second embodiment operates the damper 42 to open the cleaning liquid drain pipe 28 when the cleaning operation of the GGH 21 is started. Furthermore, when the cleaning operation of the GGH 21 is started, the calculator 41 controls so that the cleaning liquid in the cleaning water pit 29 is circulated to perform cleaning if the pH of the cleaning liquid in the cleaning water pit 29 is within a predetermined range based on the detection result of the pH meter SN3. In this case, the cleaning liquid pump 48 is operated and the cleaning water valve 49 is kept closed. Therefore, the cleaning liquid in the cleaning water pit 29 is used to clean the GGH 21. On the other hand, if the pH of the cleaning liquid in the cleaning water pit 29 is outside the range of the predetermined value, the calculator 41 controls so that cleaning is performed without circulating the cleaning liquid in the cleaning water pit 29. In this case, the cleaning liquid pump 48 is stopped and the cleaning water valve 49 is opened. Therefore, new cleaning liquid is supplied to clean the GGH 21.

[0040] Furthermore, the calculator 41 controls the drain valve 46a and the damper 42 based on the detection result of the level gauge SN4. When the detection result of the level gauge SN4 indicates that the amount of cleaning liquid in the cleaning water pit 29 has reached a predetermined upper limit amount, the calculator 41 of the second embodiment opens the drain valve 46a to control the cleaning liquid not to overflow from the cleaning water pit 29. Note that when the amount of liquid has not reached the upper limit amount, the calculator 41 closes the drain valve 46a. Furthermore, in the second embodiment, when the detection result of the liquid level meter SN4 indicates that the amount of cleaning liquid in the cleaning water pit 29 falls below a predetermined lower limit amount when cleaning work is not being performed, the calculator 41 controls the damper 42 to operate and close the cleaning liquid drain pipe 28.

[0041] (Function of Example 2) In the desulfurization device 1 of the second embodiment having the above configuration, when the differential pressure ΔP reaches a predetermined value, it is determined that it is time to perform cleaning and notifies the operator. Therefore, it is possible to automatically determine whether cleaning of the GGH 21 is necessary, that is, how dirty the GGH 21 is. Then, when the cleaning work starts, if the pH of the cleaning liquid in the cleaning water pit 29 is within a predetermined range, it is determined that the cleaning liquid is not too dirty and can be used for cleaning, and the cleaning liquid is circulated and sprayed. Therefore, compared to when it is not circulated, the amount of water used can be reduced, the environmental load can be reduced, and costs can be kept down. On the other hand, if the pH of the cleaning liquid is outside the predetermined range, it is determined that the cleaning liquid is too dirty to be used for cleaning, and new cleaning liquid is sprayed while the cleaning liquid in the cleaning water pit 29 is drained.

[0042] In addition, in the second embodiment, when the cleaning operation is started, the dam plate 31 moves to the protruding position to prevent the cleaning liquid from flowing into the storage section 3, and when the cleaning operation is not being performed, that is, when the boiler is operating, the dam plate 31 does not protrude into the inflow section 8. Therefore, it is possible to prevent the dam plate 31 from disturbing the flow of the exhaust gas while the boiler is operating (during desulfurization). Furthermore, in the second embodiment, when the amount of cleaning liquid in the cleaning water pit 29 decreases when cleaning work is not being performed, for example, while the boiler is in operation, the damper 42 closes the cleaning liquid drain pipe 28. When the amount of cleaning liquid in the cleaning water pit 29 decreases and there is no cleaning liquid in the cleaning liquid drain pipe 28, a part of the exhaust gas flowing through the flow path upstream part 7 flows through the cleaning liquid drain pipe 28 and may leak out of the exhaust gas flow path 9. In contrast, in the second embodiment, when the damper 42 closes the cleaning liquid drain pipe 28 before the cleaning liquid runs out of the cleaning liquid drain pipe 28, the cleaning liquid remains above the damper 42. That is, a water-sealed state is reached. Therefore, it is possible to suppress the exhaust gas from leaking out of the exhaust gas flow path 9. Although it is desirable to provide a water-sealing configuration, it is possible not to provide a water-sealing configuration if the amount of liquid in the cleaning water pit 29 is controlled to be approximately constant.

[0043] (Example of change) Although the embodiment and modified examples of the present invention have been described above in detail, the present invention is not limited to the above embodiment and modified examples, and various modifications can be made within the scope of the gist of the present invention described in the claims. Other modified examples (H01) to (H05) of the present invention are exemplified below. (H01) In the above embodiment, the rotary type GGH 21 is exemplified as the heat exchanger, but the present invention is not limited to this. For example, the present invention can be applied to a heat exchanger that does not rotate and in which a heat medium circulates through heat transfer tubes arranged in the upstream portion 7 and the downstream portion 4 of the flow path.

[0044] (H02) In the modification of the first embodiment, the shapes of the return portions 31a', 31a'' are not limited to the shapes shown in the examples, but can be modified to any shape, such as an arc-shaped curved shape or a polygonal column shape. (H03) In the above-mentioned embodiment, the installation position and size of the blocking plate 31 are not limited to the positions exemplified in the embodiment. For example, the installation position may be closer to the storage unit 3 than the positions exemplified in the embodiment, or closer to the cleaning liquid drain pipe 28. In addition, in the case of a retractable configuration as in embodiment 2, the blocking plate may be sized to completely block the inflow portion 8 when in the protruding position.

[0045] (H04) In the above embodiment, the configuration for determining the time to perform cleaning based on the differential pressure ΔP is illustrated, but the present invention is not limited to this. For example, it is also possible to determine the time to perform cleaning by determining a decrease in heat transfer performance from the temperature of the exhaust gas in the upstream part 7 of the flow path and the temperature of the exhaust gas flowing in the downstream part 4 of the flow path. In addition, it is also possible to determine the time to perform cleaning based on the accumulated operating time since the previous cleaning operation or the accumulated number of rotations of the GGH 21. (H05) In the above embodiment, the determination as to whether or not to circulate the cleaning liquid is made based on the pH of the cleaning liquid, but this is not limiting. For example, it is possible to determine that the cleaning liquid is dirty when the number of circulations or the amount of circulated liquid increases, and to stop circulating the cleaning liquid. In addition, for example, since the cleaning liquid that flows into the cleaning water pit 29 immediately after cleaning contains a lot of coal combustion ash and the like (is highly dirty), and the coal combustion ash and the like contained in the flowing cleaning liquid decreases as time passes from the start of cleaning, it is also possible to control the flowing cleaning liquid so that it is discharged for a certain number of minutes from the start of cleaning, and thereafter the cleaning liquid is sent to the cleaning water pit 29 and circulated for use. [Explanation of symbols]

[0046] 1...Desulfurization equipment, 3…Storage section, 4...Downstream of the flow path, 7...upstream of the flow path, 8...Inflow part, 8a...boundary, 8b...Bottom surface of exhaust gas passage, 9...Exhaust gas flow path, 11...Injector, 21...heat exchanger, 23...rotation axis, 26…cleaning machine, 28...Discharge section, 31...Regulatory components, 31a′, 31a″…returned part, 41...control unit, 42...water sealing member, 47,48...Circulation department.

Claims

1. an exhaust gas flow path including: a downstream flow path portion extending upward from a storage portion in which an absorbing liquid that absorbs sulfur content in the exhaust gas is stored; an inflow portion connected to the downstream flow path portion above the storage portion and into which the exhaust gas flows; and an upstream flow path portion connected to the upstream side of the inflow portion; an injector that injects the absorbing liquid into the exhaust gas downstream of the flow path; a heat exchanger that recovers heat from the exhaust gas in the upstream portion of the flow passage and heats the exhaust gas downstream of the injector with the recovered heat; a cleaning device disposed upstream of the flow path and configured to inject a cleaning liquid onto the heat exchanger; a discharge part provided at a bottom of the upstream part of the flow path and configured to discharge a cleaning liquid; a restricting member that is disposed downstream of the exhaust portion and upstream of a boundary between the inlet portion and the downstream portion of the flow path with respect to a gas flow direction, the restricting member restricting an inflow of the cleaning liquid into the downstream portion of the flow path; A desulfurization device comprising:

2. a return portion formed at an upper end portion of the regulating member in the gravity direction and inclined with respect to the gravity direction; The desulfurization device according to claim 1, further comprising:

3. the return portion inclined toward the downstream side in the gas flow direction as it goes upward in the gravity direction; The desulfurization device according to claim 2 , further comprising:

4. the regulating member capable of appearing and disappearing from a bottom surface of the exhaust gas flow passage; 4. The desulfurization apparatus according to claim 1, further comprising:

5. the regulating member protruding from a bottom surface of the exhaust gas flow passage when a cleaning operation is performed by spraying a cleaning liquid by the cleaning machine, and sinking into the bottom surface of the exhaust gas flow passage when the cleaning operation is completed; The desulfurization device according to claim 4, further comprising:

6. the heat exchanger configured to be capable of storing heat and to be rotatable about a rotation axis, the heat exchanger passing through an interior of the upstream portion of the flow path and an interior of the downstream portion of the flow path in sequence; 6. The desulfurization apparatus according to claim 1, further comprising:

7. a control unit that controls a timing of spraying the cleaner based on a pressure difference between an upstream side and a downstream side in a flow direction of the exhaust gas of the heat exchanger in the upstream portion of the flow passage; 7. The desulfurization apparatus according to claim 1, further comprising:

8. a circulation unit that circulates the cleaning liquid discharged from the discharge unit to the cleaning machine; 8. The desulfurization apparatus according to claim 1, further comprising:

9. a control unit that determines whether or not to circulate the cleaning liquid through the cleaning machine based on a pH value of the cleaning liquid discharged from the discharge unit; The desulfurization device according to claim 8, further comprising:

10. a water sealing member provided in the discharge portion and sealing an inlet side of the cleaning liquid; 10. The desulfurization apparatus according to claim 1, further comprising:

11. The water sealing member is constituted by a damper that closes the discharge portion; The desulfurization device according to claim 10, further comprising:

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