JP4578268B2 - Corrosion prevention method for one-fluid spray nozzle in exhaust gas temperature reduction device - Google Patents

Description

  The present invention is used for the treatment of high-temperature exhaust gas discharged from a waste incinerator, melting furnace, boiler equipment, etc., and is a pressurized hot water having a temperature higher than the boiling point of water under atmospheric pressure or room temperature. In the exhaust gas temperature reducing device, the temperature of the exhaust gas is reduced by spraying the pressurized water from the plurality of one-fluid spray nozzles into the high temperature exhaust gas in the exhaust gas temperature reducing tower as the temperature reducing water. When controlling the spray amount of pressurized hot water or pressurized water to keep the temperature of the exhaust gas to be constant, spraying is stopped when spraying of some of the one-fluid spray nozzles is stopped. The present invention relates to a method for preventing corrosion of a one-fluid spray nozzle in an exhaust gas temperature reducing device capable of preventing corrosion of a stopped one-fluid spray nozzle.

  In general, high-temperature combustion exhaust gas discharged from a garbage incinerator or melting furnace is cooled to a predetermined temperature, and then cleaned by a gas purification device such as a bag filter and released from the chimney to the atmosphere. go.

Thus, as an exhaust gas temperature reducing device for reducing the temperature of the high-temperature combustion exhaust gas, normal temperature pressurized water (one-fluid system) or a mixed fluid of compressed air and normal temperature pressurized water (two-fluid system) is used in the exhaust gas temperature reducing tower. Many spraying methods for exhaust gas have been used so far.
By the way, in recent years, an exhaust gas temperature reducing device in which pressurized hot water having a temperature higher than the boiling point of water under atmospheric pressure is sprayed into exhaust gas has been newly developed, and Japanese Patent Laid-Open No. 2000-274654 (patent document) It is published as 1).

FIG. 3 shows an example of an exhaust gas temperature reduction device using hot water previously developed by the present applicant, and the exhaust gas temperature reduction device includes an exhaust gas cooling chamber 40a, an exhaust gas inlet 40b, and an exhaust gas outlet 40c. Exhaust gas temperature reducing tower 40, hot water tank 41 for storing pressurized hot water Wh having a temperature higher than the boiling point of water under atmospheric pressure, and hot water Wh from hot water tank 41 are used in exhaust gas cooling chamber 40a. A temperature-reduced water spray nozzle 42 (one-fluid spray nozzle) that sprays the exhaust gas Gh, a pressure pump 43 that supplies hot water Wh in the hot water tank 41 to the temperature-reduced water spray nozzle 42, and a temperature-reduced water spray nozzle 42 A temperature-reducing water amount control valve 44 for adjusting the amount of hot water, a temperature detector 45a for high-temperature exhaust gas Gh flowing from the exhaust gas inlet 40b, a temperature detector 45b for low-temperature exhaust gas Gl flowing out from the exhaust gas outlet 40c, and each temperature detector 4 a, and a temperature control device 45 or the like which controls the opening and closing of the reduced amount of hot water control valve 44 based on the detection signal from 45b.
In FIG. 3, 40d is an ash outlet, 46 is an airtight holding device (opening / closing damper), C is ash, S is heated steam, and W is clean water.

In the exhaust gas temperature reducing device, the hot water Wh in the hot water tank 41 is sent to the reduced temperature water spray nozzle 42 by the internal pressure in the hot water tank 41 and the pressurized water supply force of the pressure pump 43, and the reduced temperature water spray nozzle. 42 is sprayed onto the high-temperature exhaust gas Gh in the exhaust gas cooling chamber 40a. At this time, since the hot water Wh sprayed from the temperature-reduced water spray nozzle 42 is high-pressure water having a temperature higher than the boiling point (100 ° C.) of water under atmospheric pressure, Boiling suddenly in the vicinity of the outlet to become fine particles having a particle size of about several μm to several tens of μm, and instantly evaporates into water vapor, which is exhausted by heat exchange with the hot exhaust gas Gh in the exhaust gas cooling chamber 40a. Reduce Gh.
Then, the exhaust gas Gl that has been reduced to a predetermined temperature in the exhaust gas temperature reducing tower 40 is attracted to the outside through an exhaust gas outlet 40c by an induction fan (not shown), and a gas purification device such as a bag filter (not shown). After being cleaned here, it is discharged into the atmosphere from a chimney (not shown).

  Compared with the exhaust gas temperature reducing device using room temperature water, the exhaust gas temperature reducing device described above is (1) the sprayed hot water Wh has a fine particle size of several μm to several tens μm, and instantly evaporates. Therefore, the sprayed hot water Wh remains in the form of water droplets and does not collide or adhere to the wall surface of the exhaust gas cooling chamber 40a, and the damage or wall surface of the exhaust gas cooling chamber 40a due to the adhesion of water droplets is eliminated. (2) Since the sprayed hot water Wh instantly evaporates, the cooling performance is greatly improved, and the exhaust gas cooling chamber 40a can be greatly reduced in size. (3) When the pressurizing pressure of the hot water tank 41 is sufficient, the pressurizing pump 41 is not required, the equipment can be simplified, and the running cost can be reduced. It has practical utility .

By the way, in the conventional exhaust gas temperature reducing device, the temperature-reduced water spray nozzle 42 (one-fluid spray nozzle) having a large rated spray flow rate is used, and the temperature of the temperature-reducing water amount control valve 44 is adjusted so that the hot water Wh is sprayed. By adjusting the amount, the spray amount of the hot water Wh is adjusted over a range of about 30 to 100% of the rated spray hot water amount.
However, since the turndown ratio of the temperature-reduced water spray nozzle 42 is small, inconveniences such as an increase in the spray particle size increase as the hot water flow rate decreases. Therefore, a plurality of low-temperature-capacity spray nozzles 42 are provided in two to five stages in the flow direction of the exhaust gas Gh, and the hot water Wh is sprayed by appropriately switching them. It has been found that controlling the amount is the optimal method.

Therefore, in the case where a plurality of temperature-reduced water spray nozzles 42 (one-fluid spray nozzles) are arranged in the exhaust gas temperature-decreasing tower to control the spray amount of the hot water Wh, a part of the plurality of temperature-reduced water spray nozzles 42 is used. The spraying of the reduced temperature water spray nozzle 42 may be stopped.
In this case, if the temperature-reduced water spray nozzle 42 in which spraying of the hot water Wh is stopped is arranged in the exhaust gas cooling chamber 40a, the temperature-reduced water spray nozzle 42 becomes an exhaust gas Gh containing a lot of acid gas and dust such as HCl and SOx. Since it always contacts, there exists a problem that acidic gas flows in into the temperature-reduced water spray nozzle 42, and causes corrosion. In addition, dust in the exhaust gas Gh may adhere to the nozzle hole of the temperature-reduced water spray nozzle 42 and close the nozzle hole, causing a spray failure in the next spraying.
Further, when the supply of hot water Wh is stopped while the hot water Wh is being sprayed from the temperature-reduced water spray nozzle 42, the pressure of the hot water Wh in the passage of the temperature-reduced water spray nozzle 42 is reduced, and the spray state is changed. It becomes extremely worse, and the hot water Wh flows out as it is without being atomized and wets the exhaust gas temperature reducing tower 40 with the hot water Wh, which causes dust adhesion.

Therefore, in the exhaust gas temperature reducing device in which a plurality of temperature-reduced water spray nozzles 42 (one-fluid spray nozzles) are arranged in the exhaust gas temperature-decreasing tower 40, a reduction not used as a corrosion prevention measure for the temperature-reduced water spray nozzle 42 is used. The hot water spray nozzle 42 is removed from the exhaust gas temperature reducing tower 40 so as not to come into contact with the exhaust gas Gh containing a lot of acid gas such as HCl and dust.
However, in this case, the temperature-reduced water spray nozzle 42 must be removed from the exhaust gas temperature-decreasing tower 40, and when the removed temperature-reduced water spray nozzle 42 is used again, it must be attached to the exhaust gas temperature-decreasing tower 40. In other words, another problem arises in that it takes a lot of work to remove and attach the reduced-temperature water spray nozzle 42.
JP 2000-274654 A

  The present invention has been made in view of such problems, and the object thereof is to prevent corrosion due to acid gas in the exhaust gas of the one-fluid spray nozzle that has stopped spraying and adhesion of dust, It is an object of the present invention to provide a method for preventing corrosion of a one-fluid spray nozzle in an exhaust gas temperature reducing device that can eliminate the human replacement of the spray nozzle.

  In order to achieve the above object, the invention according to claim 1 of the present invention provides a plurality of one-fluid spray nozzles using pressurized hot water having a temperature higher than the boiling point of water under atmospheric pressure or pressurized water having a normal temperature as temperature-decreasing water. In the exhaust gas temperature reducing device that sprays to the high temperature exhaust gas in the exhaust gas temperature reduction tower where the internal pressure is kept negative, a shut-off valve is provided in each inlet line of each fluid spray nozzle. In addition, an on-off valve for preventing dripping and an air release valve are connected in a branched manner to each pipeline between each shut-off valve and each one-fluid spray nozzle, and a part of the plurality of one-fluid spray nozzles When spraying of the one-fluid spray nozzle is stopped, the shut-off valve provided on the inlet side of the one-fluid spray nozzle that has stopped spraying is closed and the on-off valve provided on the outlet side of the shut-off valve is opened for spraying Remove the residual pressure of hot water or pressurized water in the one-fluid spray nozzle The on-off valve is closed and the air release valve provided on the outlet side of the on-off valve is opened, and fresh air in the atmosphere is sprayed from the air release valve by using the negative pressure in the exhaust gas temperature reducing tower. It is characterized in that it is made to flow into the stopped one fluid spray nozzle.

  Further, the invention according to claim 2 of the present invention maintains a negative pressure from a plurality of one-fluid spray nozzles by using pressurized hot water having a temperature higher than the boiling point of water under atmospheric pressure or pressurized water having a normal temperature as reduced temperature water. In the exhaust gas temperature reducing device which sprays on the exhaust gas at a high temperature in the exhaust gas temperature reducing tower, a shutoff valve is provided in each inlet line of each fluid spray nozzle, and each shutoff valve And an on-off valve for preventing liquid dripping whose outlet side communicates with an open-drain type drain receiver in each pipe line between each one-fluid spray nozzle and each one-fluid spray nozzle. When the spraying of the one-fluid spray nozzle is stopped, the shut-off valve provided on the inlet side of the one-fluid spray nozzle that has stopped spraying is closed and the on-off valve provided on the outlet side of the shut-off valve is opened. Residual pressure relief of hot water or pressurized water in the one-fluid spray nozzle that stopped spraying After that, the on-off valve was left open, and fresh air in the atmosphere was allowed to flow from the on-off valve into the one-fluid spray nozzle using the negative pressure in the exhaust gas temperature reducing tower. There is a feature.

The present invention provides an atmosphere provided on the inlet side of a single fluid spray nozzle using the negative pressure in the exhaust gas temperature reducing tower when spraying of some of the single fluid spray nozzles is stopped. Stops spraying of hot water or pressurized water because fresh air in the atmosphere flows into the one-fluid spray nozzle that stops spraying through an open / close valve that communicates with the open-drain type drain receptacle on the open valve or outlet side The one-fluid spray nozzle is replaced with fresh air, so that acid gas does not flow into the one-fluid spray nozzle, and corrosion of the one-fluid spray nozzle due to acid gas can be prevented, The life of the one-fluid spray nozzle can be extended.
Further, according to the present invention, since fresh air flowing into the one-fluid spray nozzle is ejected from the nozzle hole, dust in the exhaust gas does not adhere to the nozzle hole of the one-fluid spray nozzle, and hot water or pressurized water is eliminated. It is possible to prevent clogging of the one-fluid spray nozzle that has stopped spraying due to dust, and to spray hot water or pressurized water reliably and satisfactorily when the one-fluid spray nozzle that has stopped spraying is used again. Become.
Furthermore, since the present invention can prevent corrosion of the one-fluid spray nozzle by acid gas and adhesion of dust to the one-fluid spray nozzle, the one-fluid spray nozzle that stops spraying hot water or pressurized water is removed from the exhaust gas temperature reducing tower. Or, it is not necessary to attach a one-fluid spray nozzle to the exhaust gas temperature reducing tower, and it is possible to eliminate human replacement of the one-fluid spray nozzle.
In addition, the present invention closes the shut-off valve provided on the inlet side of the one-fluid spray nozzle that stopped spraying when the spraying of the one-fluid spray nozzle is stopped, and the liquid dripping provided on the outlet side of the shut-off valve Since the on-off valve for prevention is opened so that hot water or pressurized water in the one-fluid spray nozzle is discharged out of the exhaust gas temperature reducing tower, hot water with a large particle diameter is discharged from the one-fluid spray nozzle that has stopped operating. Without being released, it is possible to completely prevent various troubles (for example, dust adhesion, etc.) caused by the inside of the exhaust gas temperature reducing tower getting wet with hot water.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an example of an exhaust gas temperature reducing device for carrying out the method of the present invention. The exhaust gas temperature reducing device is installed in a waste incineration facility, a boiler facility or the like, and is a high temperature exhaust gas discharged from a waste incinerator or the like. Gh is reduced to a predetermined temperature.

  That is, the exhaust gas temperature reducing device includes an exhaust gas cooling tower 1 having an exhaust gas cooling chamber 1a, an exhaust gas inlet 1b, and an exhaust gas outlet 1b, a temperature reducing water tank 2 for storing normal temperature clean water W, and water under atmospheric pressure. To the hot water tank 3 for storing the pressurized hot water Wh having a temperature higher than the boiling point of the water, to the hot water tank 3, to the hot water tank 3, to the hot water tank 3, to the hot water tank 3. From a chemical injection device 5 for injecting an alkaline chemical into the supplied water W, a plurality of one-fluid spray nozzles 6 for spraying hot water Wh from the hot water tank 3 into the exhaust gas cooling chamber 1a, and the hot water tank 3 Of the hot water Wh to the one-fluid spray nozzle 6, the hot water control valve 8 for adjusting the amount of hot water supplied to the one-fluid spray nozzle 6, and the low-temperature exhaust gas Gl discharged from the exhaust gas outlet 1b. Exhaust gas temperature for controlling opening and closing of the hot water control valve 8 based on the detected temperature Necessary temperature and pressure of hot water Wh in the hot water supply pipe 11 and the control device 9, the hot water temperature control mechanism 10 that holds the temperature and pressure of the hot water Wh from the hot water tank 3 at the set values A circulating pressure control mechanism 12 that maintains a constant value, an operation switching control mechanism 13 of the one-fluid spray nozzle 6 that switches the operation of each one-fluid spray nozzle 6, and the like, which are higher than the boiling point of water at atmospheric pressure. The temperature of exhaust gas Gh is lowered by spraying high-temperature pressurized hot water Wh as temperature-reducing water from one single-fluid spray nozzle 6 or a plurality of single-fluid spray nozzles 6 to the high-temperature exhaust gas Gh in the exhaust gas temperature-decreasing tower 1. It is a thing.

  In FIG. 1, 9a is an exhaust gas temperature detector, 14 is a control valve for clean water W, 15 is a clean water supply conduit, 16 is a low-pressure steam reservoir, 17 is a steam supply conduit, and 18 is steam. Type heat exchanger, 19 is a condensate tank, 20 is a heating steam amount control valve, 21 is a hot water temperature control device, 21a is a hot water temperature detector, 22 is a blow tank, 23 is a hot water discharge conduit, 24 Is an automatic open / close valve, 25 is a hot water tank pressure control device, 25a is a hot water tank pressure detector, 26 is a hot water circulation conduit, 27 is a pressure relief valve, 28 is a hot water pressure control device, and 28a is heat. Water pressure detector, 29 is an accumulator, 30 is a hot water amount detection device, 30a is a hot water amount detector, 31 is a first shutoff valve, 31 'is a second shutoff valve, 32 is a first on-off valve, 32' Is a second open / close valve, 33 is a first atmosphere release valve, 33 'is a second atmosphere release valve, and 34 is a drain line. 35 is a first drain receiver, 35 'is a second drain receiver, 36 is an operation control device for the one-fluid spray nozzle 6, 36a is a hot water pressure detector, 37 is a gas duct, A is air in the atmosphere, and Gh is High temperature exhaust gas, Gl is low temperature exhaust gas, S is heated steam, W is clean water, and Wh is hot water.

  The exhaust gas temperature reducing tower 1 is formed in a vertical cylindrical shape by a side wall and a ceiling wall of a heat insulating structure using a heat-resistant material, and its internal space is an exhaust gas cooling chamber 1a. An exhaust gas inlet 1b through which high-temperature exhaust gas Gh discharged from a waste incinerator or the like flows into the exhaust gas cooling chamber 1a is provided at the lower side of the exhaust gas temperature reduction tower 1, and the upper side of the exhaust gas temperature reduction tower 1 Are provided with exhaust gas outlets 1b for discharging the exhaust gas Gl whose temperature has been reduced to the outside of the exhaust gas cooling chamber 1a. Further, a gas purification device such as a bag filter, an induction fan, a chimney (all not shown) and the like are sequentially connected to the exhaust gas outlet 1b through a gas duct 37. Therefore, the pressure in the exhaust gas temperature reducing tower 1 (in the exhaust gas cooling chamber 1a) is kept at a negative pressure by the induction fan.

In the exhaust gas cooling chamber 1a of the exhaust gas temperature reducing tower 1, a plurality of one-fluid spray nozzles 6 are arranged at predetermined intervals along the flow direction of the high temperature exhaust gas Gh.
In this embodiment, two one-fluid spray nozzles 6 are arranged vertically at a predetermined interval in the lower part of the exhaust gas cooling chamber 1a, and the interior of the exhaust gas cooling chamber 1a is extended from below to above. The hot water Wh can be sprayed from the one-fluid spray nozzle 6 in the same direction to the high-temperature exhaust gas Gh flowing in the same direction. For each one-fluid spray nozzle 6, a conventionally known non-return type one-fluid full cone nozzle with a small rated spray amount is used.

The hot water tank 3 includes a steam heat exchanger 18 that heats and pressurizes clean water W (containing an alkaline chemical) supplied from the temperature-reducing water tank 2 into the hot water tank 3 to a predetermined temperature and pressure. In the hot water tank 3, pressurized hot water Wh having a temperature higher than the boiling point (100 ° C.) of water under atmospheric pressure is stored.
In this embodiment, heated steam S having a pressure of 0.49 MPa and a temperature of 220 ° C. is supplied from the low pressure steam sump 16 to the steam heat exchanger 18, and the temperature is 120 ° C. to 155 ° C. and the pressure is 1. Pressurized hot water Wh of 1 MPa to 2.0 MPa is produced in the hot water tank 3.
Moreover, in the hot water tank 3, water expansion occurs when the heating water W is heated and heated by the steam heat exchanger 18, and the pressure in the hot water tank 3 increases, so the pressure in the hot water tank 3 is controlled. A hot water discharge pipe 23, an automatic opening / closing valve 24, and a hot water tank pressure control device 25 are provided. That is, in this hot water tank 3, when the pressure in the hot water tank 3 exceeds a predetermined value due to water expansion, the hot water tank pressure control device 25 opens the automatic open / close valve 24, and the hot water tank 3 The pressurized hot water Wh is discharged into the blow tank 22 through the hot water discharge pipe 23.
In this embodiment, if the state in which the pressure in the hot water tank 3 exceeds 1.05 MPa is continued for 5 seconds, an upper limit alarm is issued and the automatic open / close valve 24 is instantaneously turned on by the hot water tank pressure control device 25. Opened. If the state where the pressure in the hot water tank 3 is 0.95 MPa or less continues for 20 seconds, a lower limit alarm is issued and the automatic open / close valve 24 is closed by the hot water tank pressure control device 25 after 1 second has elapsed. Thereby, an excessive pressure rise in the hot water supply pipe 11 or in the device is prevented.

The opening amount of the hot water amount control valve 8 is controlled by the exhaust gas temperature control device 9 so that the temperature of the low temperature exhaust gas Gl discharged from the exhaust gas outlet 1b of the exhaust gas temperature reducing tower 1 is maintained at a set value. The opening degree of the hot water amount control valve 8 is adjusted, and the hot water amount is detected by the hot water amount detection device 30.
In this embodiment, the hot water amount control valve 8 includes the exhaust gas temperature detector 9a and the exhaust gas so that the temperature of the low temperature exhaust gas Gl discharged from the exhaust gas outlet 1b of the exhaust gas temperature reducing tower 1 is maintained at 180 ° C. The opening degree is controlled by the temperature control device 9.
The hot water supply pipe 11 on the inlet side of the hot water control valve 8 is provided with a shock absorbing accumulator 29 in a branched shape so that the shock pressure of the hot water supply pipe 11 system is absorbed. To be done. For example, when the pressurized hot water Wh having a temperature of 130 ° C. or higher and a pressure of 1.0 MPa or higher is sprayed from the one-fluid spray nozzle 6, the hot water amount control valve 8 and the shut-off valves 31, 31 ′ are suddenly closed. In such a case, combined with the fact that hot water pressurization by the hot water pressurization pump 7 cannot be stopped suddenly, the pressure in the hot water supply pipe 11 rises, Although the pressure load on other devices increases, by providing the accumulator 29, the impact pressure is effectively absorbed.

The hot water temperature control mechanism 10 includes a heating steam amount control valve 20 provided in the steam supply pipe 17 and the temperature of the hot water Wh flowing in the hot water supply pipe 11 on the outlet side of the pressurizing pump 7. And a hot water temperature control device 21 that controls the opening and closing of the heating steam amount control valve 20 based on the detected temperature of the hot water Wh from the hot water temperature detector 21a. Thus, the temperature and pressure of the hot water Wh from the hot water tank 3 are always kept at the set values.
That is, the temperature of the hot water Wh from the pressurizing pump 7 is held at the set value by the hot water temperature control device 21, and when the temperature of the hot water Wh exceeds the set value (155 ° C.) on the high temperature side. The hot water temperature control device 21 closes the heating steam amount control valve 20 (fully closed), and the flow of the heating steam S from the low pressure steam sump 16 to the steam heat exchanger 18 is stopped. Further, when the temperature of the hot water Wh becomes lower than the set value (120 ° C.) on the low temperature side, the hot water temperature control device 21 opens (fully opens) the heating steam amount control valve 20, and from the low pressure steam sump 16. Heated steam S flows into the steam heat exchanger 18.
In this embodiment, the temperature of the hot water Wh flowing through the hot water supply pipe 11 is maintained at approximately 135 ° C.

The circulation pressure control mechanism 12 is a hot water circulation pipe that connects a hot water supply pipe 15 on the inlet side of the hot water tank 3 and a hot water supply pipe 11 on the inlet side of the hot water amount control valve 8. 26, a pressure relief valve 27 provided in the hot water circulation pipe 26, and a hot water pressure for detecting the pressure of the hot water Wh flowing in the hot water supply pipe 11 on the inlet side of the hot water amount control valve 8. It comprises a detector 28a and a hot water pressure control device 28 that controls the opening and closing of the pressure relief valve 27 based on the detected pressure of the hot water Wh from the hot water pressure detector 28a. The temperature and pressure of the hot water Wh are always maintained at set values.
That is, the pressure of the hot water Wh from the pressurizing pump 7 is held at the set value by the hot water pressure control device 28, and the pressure of the hot water Wh exceeds the set value (2.0 MPa) on the high pressure side. Then, the pressure relief valve 27 is opened (fully opened) by the hot water pressure controller 28, and the hot water Wh is returned into the hot water tank 3 through the hot water circulation pipe 26. When the pressure of the hot water Wh becomes lower than the set value (1.1 MPa) on the low pressure side, the pressure relief valve 27 is closed (fully closed) by the hot water pressure control device 28, and the hot water Wh There is no return to the hot water tank 3.
In this embodiment, the pressure of the hot water Wh flowing in the hot water supply pipe 11 is maintained at about 1.4 MPa.

  The operation switching control mechanism 13 of the one-fluid spray nozzle 6 includes a first shut-off valve 31 provided in the hot water supply pipe 11 on the inlet side of the upper one-fluid spray nozzle 6 and a lower one-fluid spray. The second shutoff valve 31 ′ provided in the hot water supply pipe 11 on the inlet side of the nozzle 6 and the hot water supply pipe 11 on the outlet side of the first shutoff valve 31 are connected in a branched manner. The outlet side of the first on-off valve 32 for preventing dripping connected to the tank-like first drain receiver 35 and the hot water supply pipe 11 on the outlet side of the second shut-off valve 31 'are branched. A second on-off valve 32 'for preventing dripping and having an outlet side connected to a tank-like second drain receiver 35', and a hot water supply pipe on the outlet side of the first on-off valve 32 A first atmospheric release valve 33 connected to the passage 11 in a branched manner and having its outlet side opened to the atmosphere, and hot water supply for the outlet side of the second release valve A second atmosphere release valve 33 ′ connected in a branched manner to the passage 11 and having its outlet side opened to the atmosphere, and hot water Wh flowing in the hot water supply pipe 11 on the outlet side of the hot water amount control valve 8. A hot water pressure detector 36a for detecting the pressure, and the shutoff valves 31, 31 ', the on-off valves 32, 32' and the atmospheric release valves 33 based on the detected pressure of the hot water Wh from the hot water pressure detector 36a. , 33 ′ and an operation control device 36 that controls opening and closing of the hot water supply control valve 8, respectively, and is operated based on the pressure of the hot water Wh flowing in the hot water supply pipe 11 on the outlet side of the hot water amount control valve 8. The number of the one-fluid spray nozzles 6 is switched, and the hot water Wh in the one-fluid spray nozzle 6 whose operation is stopped is extracted, and fresh air A is caused to flow into the one-fluid spray nozzle 6.

That is, in the operation switching control mechanism 13 of the one-fluid spray nozzle 6, the spray amount control of the hot water Wh is performed so as to keep the temperature of the exhaust gas Gl discharged from the exhaust gas outlet 1b of the exhaust gas temperature reducing tower 1 constant. When the pressure of the hot water Wh flowing in the hot water supply pipe 11 on the downstream side of the hot water amount control valve 8 is equal to or higher than the set value on the high pressure side, one fluid spray on the upper side and the lower side When the hot water Wh is sprayed from the nozzles 6 respectively, and when the pressure of the hot water Wh is equal to or lower than the set value on the low pressure side, one one-fluid spray nozzle 6 (upper one-fluid spray nozzle 6) The operation of each one-fluid spray nozzle 6 is switched by the operation switching control mechanism 13 so that spraying is performed only from the above.
In this embodiment, when the state where the pressure of the hot water Wh exceeds 1.5 MPa continues for 15 seconds or more, an upper limit alarm is issued, and the operation control device 36 performs the first operation within 10 seconds from the transmission of the upper limit alarm. The two shutoff valves 31 'are controlled to be opened, and the lower one-fluid spray nozzle 6 is switched to the operating state. At this time, the operation control device 36 opens the second shut-off valve 31 ′ after confirming that the second on-off valve 32 ′ and the second atmosphere release valve 33 ′ are fully closed.
When the state where the pressure of the hot water Wh is 0.3 MPa or less continues for 25 seconds or more, a lower limit alarm is issued, and the second shut-off valve 31 ′ is set by the operation control device 36 after 20 seconds from the transmission of the lower limit alarm. Under closing control, the lower one fluid spray nozzle 6 is switched to a non-operating state (stopped state). At this time, the operation control device 36 fully closes the second shut-off valve 31 ', then opens the second on-off valve 32' for preventing dripping and remains in the lower one fluid spray nozzle 6. The hot water Wh is discharged to the second drain receiver 35 ', and after a few seconds, the second on-off valve 32' is fully closed and the second atmospheric release valve 33 'is fully opened. As a result, the fresh air in the atmosphere flows into the lower one-fluid spray nozzle 6 through the open second atmosphere release valve 33 ′ due to the negative pressure in the exhaust gas temperature reducing tower 1, and the one-fluid spray nozzle 6 is ejected into the exhaust gas cooling chamber 1a.

Thus, in the exhaust gas temperature reducing device described above, the clean water W containing alkaline chemicals supplied from the temperature-reducing water tank 2 to the hot water tank 3 by the temperature-reducing water supply pump 4 is contained in the hot water tank 3. After being heated and pressurized to a predetermined temperature and pressure by the steam heat exchanger 18, the exhaust gas is reduced from the one-fluid spray nozzle 6 via the hot water control valve 8 and the shut-off valves 31 and 31 ′ by the pressurizing pump 7. It sprays on the hot exhaust gas Gh in the warm tower 1.
Since the hot water Wh sprayed from the one-fluid spray nozzle 6 is high-pressure water having a temperature higher than the boiling point of water under atmospheric pressure, it suddenly boils under reduced pressure near the outlet of the nozzle hole of the one-fluid spray nozzle 6. In addition to fine particles having a particle diameter of several μm to several tens of μm, it is instantly evaporated to become water vapor, and heat exchange with the high temperature exhaust gas Gh in the exhaust gas cooling chamber 1a is performed to cool the exhaust gas Gh.
The exhaust gas Gl reduced in temperature to a predetermined temperature is attracted to the outside through the exhaust gas outlet 1b by an induction fan (not shown), flows into a gas purification device (not shown) such as a bag filter, and is purified there. Then, it is discharged into the atmosphere from a chimney (not shown).

In the exhaust gas temperature reducing device, when performing the spray amount control of the hot water Wh so as to keep the temperature of the exhaust gas Gl discharged from the exhaust gas outlet 1b of the exhaust gas temperature reducing tower 1 constant, Among the lower one fluid spray nozzles 6, the operation of the lower one fluid spray nozzle 6 is stopped or the stopped one fluid spray nozzle 6 is operated again.
That is, when the operation of the lower one-fluid spray nozzle 6 among the upper and lower one-fluid spray nozzles 6 is stopped, the operation control device 36 fully closes the second shut-off valve 31 ', The second on-off valve 32 'for preventing dripping is opened to discharge the hot water Wh remaining in the lower one-fluid spray nozzle 6 to the second drain receiver 35'. 36 fully closes the second on-off valve 32 'and fully opens the second air release valve 33'. Then, the fresh air in the atmosphere flows into the lower one-fluid spray nozzle 6 through the second atmosphere release valve 33 ′ in the open state due to the negative pressure in the exhaust gas temperature reducing tower 1, and the one-fluid spray nozzle 6 is ejected into the exhaust gas cooling chamber 1a.
When the lower one-fluid spray nozzle 6 that has stopped operating is restarted, the operation control device 36 fully closes the second atmosphere release valve 33 ′, and the second on-off valve 32 ′ and the second on-off valve 32 ′. After confirming that the second air release valve 33 'is fully closed, the second shut-off valve 31' is opened. Thereby, the hot water Wh is sprayed from the lower one fluid spray nozzle 6 into the exhaust gas cooling chamber 1a.

As described above, in the exhaust gas temperature reducing device, fresh air is released from the atmosphere release valve 33 ′ using the negative pressure in the exhaust gas temperature reducing tower 1 in the one-fluid spray nozzle 6 in which the spraying of hot water Wh is stopped. Since the air is allowed to flow in, the acidic gas in the exhaust gas Gh does not flow into the one-fluid spray nozzle 6 in which the spraying of the hot water Wh is stopped, and the one-fluid spray nozzle 6 is corroded by the acidic gas. It is possible to prevent the dust from adhering to the nozzle hole of the one-fluid spray nozzle 6. As a result, there is no need to remove the one-fluid spray nozzle 6 that stops spraying the hot water Wh from the exhaust gas temperature-decreasing tower 1 or to attach the one-fluid spray nozzle 6 to the exhaust gas temperature-decreasing tower 1. It is possible to save the labor required for the exchange of 6. However, since the hot water Wh in the one-fluid spray nozzle 6 that has stopped spraying is discharged out of the exhaust gas temperature reducing tower 1, the hot water Wh is released from the one-fluid spray nozzle 6 that has stopped spraying. Therefore, various troubles caused by the inside of the exhaust gas temperature reducing tower 1 being wet by the hot water Wh can be prevented.
Further, since the exhaust gas temperature reducing device is provided with the hot water discharge pipe 23 for controlling the pressure in the hot water tank 3, the automatic open / close valve 24, and the hot water tank pressure control device 25 in the hot water tank 3, Even if water expansion occurs at the time of heating and heating the upper water W, excessive pressure rise in the hot water supply pipe 11 or in the equipment can be prevented by the operation of the automatic opening / closing valve 24.
Further, the exhaust gas temperature reducing device opens and closes the heating steam amount control valve 20 for controlling the flow rate of the heating steam S flowing into the steam heat exchanger 18 and the heating steam amount control valve 20 based on the detected temperature of the hot water Wh. Since the hot water temperature control mechanism 10 including the hot water temperature control device 21 to be controlled is provided, the temperature and pressure of the hot water Wh are always maintained at the set values, and the stable and good hot water Wh Spraying becomes possible.
In addition, the exhaust gas temperature reducing device includes a hot water circulation pipe 26 for returning a part of the hot water Wh into the hot water tank 3, a pressure relief valve 27 provided in the hot water circulation pipe 26, and hot water. Since the circulating pressure control mechanism 12 including the hot water pressure control device 28 that controls the opening and closing of the pressure relief valve 27 based on the detected pressure of Wh is provided, the heat pressure can be increased even at the start of operation or at the time of low amount hot water spray. The temperature and pressure of the water Wh can be prevented from decreasing, and the temperature and pressure of the hot water Wh in the hot water supply pipe 11 can be maintained at necessary values.
In addition, since the exhaust gas temperature reducing device is provided with an impact-absorbing accumulator 29 on the inlet side of the hot water amount control valve 8, even if the hot water amount control valve 8 and the shut-off valves 31, 31 'are suddenly closed, The impact energy from the water hammer is absorbed by the accumulator 29, and the hot water supply conduit 11 and equipment are not adversely affected.

  FIG. 2 shows an example of an exhaust gas temperature reducing device for carrying out another method of the present invention. The exhaust gas temperature reducing device includes an exhaust gas temperature reducing tower 1 having an exhaust gas cooling chamber 1a, an exhaust gas inlet 1b and an exhaust gas outlet 1b, Dewarmed water tank 2 for storing normal temperature water W, hot water tank 3 for storing pressurized hot water Wh having a temperature higher than the boiling point of water under atmospheric pressure, and upper water W from dewarmed water tank 2 Is supplied to the hot water tank 3, the temperature-decreasing water supply pump 4, the chemical injection device 5 for injecting alkaline chemicals into the clean water W supplied to the hot water tank 3, and the hot water Wh from the hot water tank 3 to cool the exhaust gas. A plurality of one-fluid spray nozzles 6 spraying into the chamber 1a, a pressure pump 7 for supplying hot water Wh from the hot water tank 3 to the one-fluid spray nozzle 6, and an amount of hot water supplied to the one-fluid spray nozzle 6 Hot water amount control valve 8 to be adjusted and low temperature exhaust gas G discharged from the exhaust gas outlet 1b An exhaust gas temperature control device 9 that controls opening and closing of the hot water amount control valve 8 based on the detected temperature of the hot water, a hot water temperature control mechanism 10 that holds the temperature and pressure of the hot water Wh from the hot water tank 3 at a set value, A circulation pressure control mechanism 12 for maintaining the temperature and pressure of the hot water Wh in the water supply pipe 11 at necessary values, and an operation switching control mechanism 13 for each fluid spray nozzle 6 for switching the operation of each fluid spray nozzle 6. Etc., and the heated hot water Wh having a temperature higher than the boiling point of water under atmospheric pressure is used as temperature-decreasing water, and the exhaust gas temperature-decreasing tower 1 from one single-fluid spray nozzle 6 or a plurality of one-fluid spray nozzles 6. The temperature of the exhaust gas Gh is lowered by spraying on the high temperature exhaust gas Gh.

  In FIG. 2, 9a is an exhaust gas temperature detector, 14 is a control valve for clean water W, 15 is a conduit for supplying clean water, 16 is a low-pressure steam reservoir, 17 is a conduit for supplying steam, and 18 is steam. Type heat exchanger, 19 is a condensate tank, 20 is a steam control valve, 21 is a temperature control device, 21a is a hot water temperature detector, 22 is a blow tank, 23 is a hot water discharge line, and 24 is automatic. On-off valve, 25 is a hot water tank pressure control device, 25a is a hot water tank pressure detector, 26 is a hot water circulation conduit, 27 is a pressure relief valve, 28 is a hot water pressure control device, and 28a is a hot water pressure. Detector, 29 is an accumulator, 30 is a hot water quantity detection device, 30a is a hot water quantity detector, 31 is a first shut-off valve, 31 'is a second shut-off valve, 32 is a first on-off valve, 32' is a first shut-off valve 2 on-off valve, 34 is a drain pipe line, 35 is a first drain receiver that is open to the atmosphere, and 35 ′ is open to the atmosphere Receiving a second drain, the 36 actuation controller of one fluid spray nozzle 6, 36a is hot water pressure detector, 37 is a gas duct.

  In the exhaust gas temperature reducing device, the first atmosphere release valve 33 and the second atmosphere release valve 33 ′ are omitted, and the first drain receiver 35 and the second drain receiver 35 ′ are of the atmosphere release type. Is configured in the same structure as the exhaust gas temperature reducing device shown in FIG. 1, and the same parts and members as those in the exhaust gas temperature reducing device shown in FIG.

Thus, in the exhaust gas temperature reducing device, when performing the spray amount control of the hot water Wh so as to keep the temperature of the exhaust gas Gl discharged from the exhaust gas outlet 1b of the exhaust gas temperature reducing tower 1 constant, Of the upper and lower one-fluid spray nozzles 6, the operation of the lower one-fluid spray nozzle 6 is stopped or the stopped one-fluid spray nozzle 6 is operated again.
That is, when the operation of the lower one-fluid spray nozzle 6 among the upper and lower one-fluid spray nozzles 6 is stopped, the operation control device 36 fully closes the second shut-off valve 31 ', The second on-off valve 32 'for preventing dripping is opened, and the hot water Wh remaining in the lower one-fluid spray nozzle 6 is discharged to the second drain receiver 35'. Leave valve 32 'open. Then, coupled with the outlet side of the second on-off valve 32 ′ communicating with the second drain receiver 35 ′ that is open to the atmosphere, the fresh air in the atmosphere is released by the negative pressure in the exhaust gas temperature reducing tower 1. The fluid flows into the lower one-fluid spray nozzle 6 through the second open / close valve 32 ', and is ejected from the one-fluid spray nozzle 6 into the exhaust gas cooling chamber 1a.
When the lower one-fluid spray nozzle 6 whose operation has been stopped is operated again, the operation control device 36 fully closes the second on-off valve 32 'and opens the second shut-off valve 31'. . Thereby, the hot water Wh is sprayed from the lower one fluid spray nozzle 6 into the exhaust gas cooling chamber 1a.

  This exhaust gas temperature reducing device also allows fresh air to flow from the on-off valve into the one-fluid spray nozzle 6 that stops spraying the hot water Wh using the negative pressure in the exhaust gas temperature reducing tower 1. The same effect as the exhaust gas temperature reducing device shown in FIG. 1 can be obtained.

  In the above embodiment, the steam heat exchanger 18 is used as the heating source of the hot water Wh, but the heat of the combustion exhaust gas or the heat of a separately provided heating burner is used as the heating source. You may do it. In addition, in a facility equipped with a boiler or a waste heat boiler, the continuous blow water of the boiler or the boiler feed water may be used as the hot water Wh, or the hot water Wh generated in the deaerator is used. You can use it.

  In the above embodiment, two one-fluid spray nozzles 6 are arranged vertically in the exhaust gas cooling chamber 1a, but three to five one-fluid sprays are disposed in the exhaust gas cooling chamber 1a. The nozzle 6 may be arranged at an appropriate position. In this case, it goes without saying that the shut-off valves 31 and 31 'are provided on the inlet side of each one-fluid spray nozzle 6.

  In the above embodiment, the high-temperature exhaust gas Gh is allowed to flow from below the exhaust gas temperature-decreasing tower 1 and a plurality of one-fluid spray nozzles 6 are disposed in the lower part of the exhaust gas temperature-decreasing tower 1. In addition, the high-temperature exhaust gas Gh may be a downward flow that flows downward from above, and a plurality of one-fluid spray nozzles 6 may be disposed in the upper part of the exhaust gas temperature-decreasing tower 1.

  In the above embodiment, the operation of the lower one-fluid spray nozzle 6 is stopped when the pressure of the hot water Wh is lowered. The operation of the upper one fluid spray nozzle 6 may be stopped.

  In the above embodiment, the opening / closing control of each shut-off valve 31, 31 ', each opening / closing valve 32, 32' and each atmosphere opening valve 33, 33 'is automatically performed by the operation control device 36. The opening / closing control of each shut-off valve 31, 31 ', each opening / closing valve 32, 32' and each atmosphere opening valve 33, 33 'may be performed manually.

  In the above embodiment, pressurized hot water Wh having a temperature higher than the boiling point of water under atmospheric pressure is sprayed from the one-fluid spray nozzle 6 to the exhaust gas Gh in the exhaust gas temperature-decreasing tower 1 as temperature-reducing water. Although the temperature of the exhaust gas Gh is decreased, the temperature of the exhaust gas Gh may be decreased by spraying the pressurized water at normal temperature as the temperature-reduced water from the one-fluid spray nozzle 6 to the exhaust gas Gh in the exhaust gas temperature-decreasing tower 1.

1 is a schematic system diagram of an exhaust gas temperature reducing device for implementing a method of the present invention. It is a schematic system diagram of the exhaust gas temperature reducing device for carrying out another method of the present invention. It is a schematic system diagram which shows an example of the waste gas temperature reducing apparatus using the conventional hot water.

Explanation of symbols

  1 is an exhaust gas temperature reducing tower, 6 is a one-fluid spray nozzle, 11 is a hot water supply pipe, 31 and 31 'are shut-off valves, 32 and 32' are on-off valves, 33 and 33 'are air release valves, 35 'is a drain receiver, A is air, Gh is high temperature exhaust gas, Wh is hot water.

Claims (2)

  High-temperature exhaust gas in the exhaust gas temperature-reduction tower in which pressurized hot water at a temperature higher than the boiling point of water at atmospheric pressure or pressurized water at room temperature is used as temperature-reduced water and the inside is maintained at a negative pressure from a plurality of one-fluid spray nozzles In the exhaust gas temperature reducing device that is sprayed to each one, a shutoff valve is provided in each inlet line of each fluid spray nozzle, and each pipe between each shutoff valve and each fluid spray nozzle. The on-off valve for preventing dripping and the air release valve are connected to the road in a branched manner, and when the spraying of some of the one-fluid spray nozzles is stopped, the spray is stopped. The shut-off valve provided on the inlet side of the fluid spray nozzle is closed, and the on-off valve provided on the outlet side of the shut-off valve is opened to stop the spraying of hot water or pressurized water in the one-fluid spray nozzle. And then close the on-off valve and install it on the outlet side of the on-off valve. The air release valve is opened and fresh air in the atmosphere is allowed to flow from the atmosphere release valve into the one-fluid spray nozzle using the negative pressure in the exhaust gas temperature reducing tower. A method for preventing corrosion of a one-fluid spray nozzle in an exhaust gas temperature reducing device.   High-temperature exhaust gas in the exhaust gas temperature-reduction tower in which pressurized hot water at a temperature higher than the boiling point of water at atmospheric pressure or pressurized water at room temperature is used as temperature-reduced water and the inside is maintained at a negative pressure from a plurality of one-fluid spray nozzles In the exhaust gas temperature reducing device that is sprayed to each one, a shutoff valve is provided in each inlet line of each fluid spray nozzle, and each pipe between each shutoff valve and each fluid spray nozzle. When the on-off valve for dripping prevention whose outlet side communicates with the drain receiver of the atmosphere open type is connected in a branched manner, and spraying of some one-fluid spray nozzles among a plurality of one-fluid spray nozzles is stopped In addition, the shutoff valve provided on the inlet side of the one-fluid spray nozzle that has stopped spraying is closed, and the on-off valve provided on the outlet side of the shut-off valve is opened to stop spraying, and the hot water in the one-fluid spray nozzle that has stopped spraying Or, remove the residual pressure of the pressurized water and then open the on-off valve. The exhaust gas temperature reducing device is characterized in that fresh air in the atmosphere is allowed to flow from the on-off valve into the one-fluid spray nozzle using the negative pressure in the exhaust gas temperature reduction tower. For preventing corrosion of a one-fluid spray nozzle in Japan.

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