JP6328916B2 - Waste heat recovery boiler and cleaning method - Google Patents

Description

  The present invention relates to a mechanism for cleaning the inside of an exhaust heat recovery boiler, and a cleaning method thereof, and in particular, a water treatment method of an exhaust heat recovery boiler is changed from phosphate treatment to volatile substance treatment (High- The present invention relates to an exhaust heat recovery boiler having a mechanism for cleaning the inside when converting to AVT (All Volatile Treatment), and a cleaning method thereof.

In the gas turbine combined cycle power plant, an exhaust heat recovery boiler (HRSG) is installed for the purpose of recovering exhaust heat of the gas turbine.
In conventional exhaust heat recovery boilers, phosphate treatment using ammonia and hydrazine in the feed water system and phosphate in the boiler water system has been used. In recent years, as the inlet gas of exhaust heat recovery boilers has become hot, there is a problem of thinning due to acid phosphate corrosion or alkali corrosion on the inner surface of carbon steel evaporator piping caused by phosphate used for boiler water treatment. It was. Further, it is known that troubles due to flow accelerated corrosion (FAC) occur in the economizer. As a method for avoiding these troubles, conversion to a boiler water treatment method that does not use phosphorus was examined.

  As a water treatment method that does not use phosphorus in a boiler system, there is a volatile substance treatment (AVT: All Volatile Treatment). High-AVT (high pH water treatment) in which the supply amount of ammonia is increased and the feed water pH is set higher than AVT can suppress corrosion of piping (Non-patent Document 1). Moreover, in High-AVT, the water supply process which does not use hydrazine is examined (nonpatent literature 2). Moreover, it becomes possible to suppress the above-mentioned FAC by performing a water supply process at high pH.

When scale is generated on the inner surface of the evaporator during phosphating, if it is converted to High-AVT without chemical cleaning, corrosion proceeds from the scale.
Therefore, in order to switch from phosphating to High-AVT, it is necessary not only to modify the equipment but also to clean the boiler system. Further, by washing the boiler system including the economizer in accordance with High-AVT, it is possible to suppress heat transfer inhibition due to scale adhesion in the economizer.

  Patent Document 1 discloses a method of cleaning the inside of a heat recovery steam generator boiler by putting alkaline cleaning chemicals in a steam drum and performing a load operation of the gas turbine more than no load in a combined power plant of a gas turbine and a steam turbine. To do. Patent Document 2 discloses a cleaning method for circulating a heated cleaning liquid in a heat transfer tube in a state where an exhaust gas supply port and an exhaust gas outlet of an exhaust heat recovery boiler are closed.

  Patent Document 3 discloses a method of removing scale by adding aldonic acid or aldonic acid salt and a chelating agent (for example, ethylenediaminetetraacetic acid) to a boiler water system during boiler operation.

JP-A-9-79504 JP-A-11-37405 JP 2011-212591 A

Mitsubishi Heavy Industries Technical Report Vol. 50 No. 1 (2013) Mitsubishi Heavy Industries Technical Review Vol.46 No. 2 (2009)

  Generally, a fin tube having a high heat radiation amount is employed in an evaporator of an exhaust heat recovery boiler. However, in the cleaning method using the heated cleaning liquid as in Patent Document 2, for example, the temperature of the cleaning liquid is reduced in the fin tube. For this reason, the cleaning effect decreases. In order to suppress the temperature drop of the cleaning liquid, it is necessary to install a large-scale temperature raising facility in the boiler system or start up the gas turbine and raise the temperature by exhaust gas.

  The exhaust heat recovery boiler is composed of a plurality of drums and an evaporator. To apply High-AVT, it is necessary to clean all drums and evaporators. When cleaning a plurality of drums and evaporators, it is required to simplify the cleaning system as much as possible in order to reduce the cost for cleaning preparation. Furthermore, it is necessary to carry out cleaning in a process that reduces the time and cost required for cleaning (chemical amount, labor cost, etc.).

  The present invention has been made in view of the above problems, and when converting from a phosphate treatment to a High-AVT as a water treatment method, an exhaust heat recovery boiler that can clean the inside of a pipe at a low cost and in a short time. And a cleaning method thereof.

  A first aspect of the present invention is an exhaust heat recovery boiler including an exhaust heat recovery unit having an evaporator, a steam drum, and a economizer, and includes a cleaning unit for cleaning the exhaust heat recovery unit. The cleaning unit includes a storage unit that stores a normal temperature cleaning liquid containing a neutral rust remover, a cleaning pipe that guides the cleaning liquid to the exhaust heat recovery unit and discharges the cleaning liquid from the exhaust heat recovery unit, and the cleaning pipe. A cleaning liquid supply unit including a pump for circulating the cleaning liquid, a measuring unit for measuring the water level of the cleaning liquid in the steam drum, and provided at an intermediate position of the cleaning pipe, based on a measurement value of the measuring unit And a valve for adjusting to a predetermined water level of the cleaning liquid in the steam drum.

  A second aspect of the present invention is a cleaning method for cleaning the exhaust heat recovery unit in an exhaust heat recovery boiler including an exhaust heat recovery unit having an evaporator, a steam drum, and a economizer, A normal temperature cleaning liquid containing a neutral rust remover is supplied to the exhaust heat recovery unit until the steam drum is filled with the cleaning liquid, and after the steam drum is filled with the cleaning liquid, the exhaust heat recovery unit The supply of the cleaning liquid to is stopped, the inside of the exhaust heat recovery unit is immersed in the cleaning liquid at room temperature for a predetermined time, and after the predetermined time has elapsed, the cleaning is performed from the exhaust heat recovery unit The cleaning liquid is discharged.

  A third aspect of the present invention is a cleaning method for cleaning the inside of the exhaust heat recovery unit in an exhaust heat recovery boiler including an exhaust heat recovery unit having an evaporator, a steam drum, and a economizer, A normal temperature cleaning liquid containing a neutral rust remover is supplied to the exhaust heat recovery unit until the steam drum is filled with the cleaning liquid, and after the steam drum is filled with the cleaning liquid, While the cleaning liquid is circulated, the interior of the exhaust heat recovery unit is immersed in the cleaning liquid at room temperature for a predetermined time, and after the predetermined time has elapsed, the cleaning liquid is discharged from the exhaust heat recovery unit that has been cleaned. The

In the exhaust heat recovery boiler and cleaning method of the present invention, the inside of the pipe is cleaned using a normal temperature cleaning liquid containing a neutral rust remover, so there is no need to install a temperature raising equipment, and no cleaning liquid preheating step is required. It is. In addition, since a cleaning liquid containing a neutral rust remover is used, it is not necessary to attach or detach accessories or devices that are sensitive to acids such as SUS parts for cleaning. Therefore, the time and cost required for cleaning are reduced.
In the present invention, the cleaning process is simplified. In addition, since the cleaning is performed by managing the amount of cleaning liquid in the steam drum, it is possible to reduce the amount of water and chemical used for cleaning.
In particular, in the cleaning method of the second aspect, since the inside of the pipe is immersed in the cleaning liquid in a state where the circulation of the cleaning liquid is stopped, the power for operating the pump is advantageously reduced.

  In the second aspect and the third aspect, the inside of the exhaust heat recovery unit is washed with the cleaning liquid when the method of treating the water flowing through the exhaust heat recovery unit is changed from phosphate water treatment to High-AVT water treatment. It is preferable to do.

In the first aspect, it is preferable that the cleaning pipe guides the cleaning liquid to the economizer.
2nd aspect and 3rd aspect WHEREIN: It is preferable that the said washing | cleaning liquid is supplied to the said economizer, and the inside of the said economizer is immersed in the said cleaning liquid.

  In the said aspect, the inside of a economizer can be wash | cleaned and the suppression effect of the heat transfer inhibition mentioned above can be acquired.

  The exhaust heat recovery boiler of the first aspect includes a plurality of the exhaust heat recovery units that generate steam having different pressures, and the cleaning liquid feeding unit is connected to the exhaust heat recovery unit on the most upstream side of the cleaning liquid, A connecting pipe connects the plurality of exhaust heat recovery units in series, the cleaning pipe is connected to the exhaust heat recovery unit on the most downstream side of the cleaning liquid, and the pump is configured to perform all the exhaust heat in one cleaning. The cleaning liquid may be fed to the collection unit.

  The cleaning methods of the second and third aspects include a plurality of the exhaust heat recovery units that generate vapors having different pressures, and the plurality of exhaust heat recovery units are connected in series to the flow of the cleaning liquid. In the exhaust heat recovery boiler, the cleaning liquid may be supplied to the plurality of exhaust heat recovery units in one cleaning.

  According to the above aspect, since the cleaning system is simple, the equipment cost is reduced. In addition, the cleaning process is simple and the time required for cleaning can be shortened.

  The exhaust heat recovery boiler of the first aspect includes a plurality of the exhaust heat recovery units that generate steam having different pressures, the cleaning pipe is connected in parallel to each of the plurality of exhaust heat recovery units, and the pump The cleaning liquid may be supplied to all the exhaust heat recovery units in one cleaning.

  In the cleaning method according to the second aspect and the third aspect, a plurality of the exhaust heat recovery units that generate steam having different pressures are provided, and the plurality of exhaust heat recovery units are connected in parallel to the flow of the cleaning liquid. In the exhaust heat recovery boiler, the cleaning liquid may be supplied to the plurality of exhaust heat recovery units in one cleaning.

  According to the above aspect, since the cleaning system is simple, the equipment cost is reduced. In addition, the cleaning process is simple and the time required for cleaning can be shortened.

  The exhaust heat recovery boiler according to the first aspect includes a plurality of the exhaust heat recovery units that generate steam having different pressures, the cleaning pipe is connected to each of the plurality of exhaust heat recovery units, and the pump is The cleaning liquid may be supplied from the storage unit to one of the exhaust heat recovery units by one cleaning.

  In the cleaning method according to the second aspect and the third aspect, a plurality of the exhaust heat recovery units that generate steam having different pressures are provided, and the plurality of exhaust heat recovery units are connected in parallel to the flow of the cleaning liquid. In the exhaust heat recovery boiler, the cleaning liquid may be supplied to one exhaust heat recovery unit in one cleaning.

  In the exhaust heat recovery boiler of the above aspect, the amount of cleaning liquid to be fed in one cleaning can be reduced. For this reason, the amount of water and the amount of chemicals required for cleaning can be reduced. Furthermore, since the pump for supplying the cleaning liquid is sufficient even if the capacity is small, the equipment cost can be reduced.

  In this case, in the exhaust heat recovery boiler of the first aspect, the plurality of exhaust heat recovery units are arranged in the vertical direction, and the first connecting pipes connect the evaporators adjacent in the vertical direction in series, A second connecting pipe connects the steam drums adjacent in the vertical direction in series, and the cleaning liquid in the evaporator that has been cleaned is washed by the gravity through the first connecting pipe. The cleaning liquid in the steam drum, which has been supplied to the evaporator located below the evaporator where the cleaning is performed, and cleaned is performed by the gravity through the second connecting pipe by gravity. It can be set as the structure fed to the said steam drum located below the broken steam drum.

  In the cleaning method of the second aspect and the third aspect, in the exhaust heat recovery boiler in which the plurality of exhaust heat recovery units are arranged in the vertical direction, the cleaning liquid in the evaporator that has been cleaned is caused by gravity. The cleaning liquid in the steam drum, which is fed to the lower evaporator below the cleaned evaporator and is cleaned, is lower than the cleaned steam drum by gravity. To the adjacent steam drum on the side.

  In the above vertical exhaust heat recovery boiler, the cleaning liquid in the exhaust heat recovery unit that has been cleaned is fed to another exhaust heat recovery unit using the vertical position level difference of each exhaust heat recovery unit. It is possible. That is, since the power for transferring the cleaning liquid is unnecessary, the operating cost at the time of cleaning can be further reduced.

  In this case, in the exhaust heat recovery boiler according to the first aspect, the first communication pipe connects the evaporators of the plurality of exhaust heat recovery sections in series, and the second communication pipe is the plurality of exhaust heat recovery sections. The steam drums are connected in series, a transfer pump is installed in each of the first communication pipe and the second communication pipe, and the transfer pump supplies the cleaning liquid in the evaporator that has been cleaned. The cleaning liquid in the steam drum which has been cleaned is fed to the other vapor drum via the second communication pipe while being fed to the other evaporator via the first communication pipe. It can be set as the structure which supplies.

  In the cleaning methods of the second aspect and the third aspect, the evaporators of the plurality of exhaust heat recovery units are connected in series, the steam drums of the plurality of exhaust heat recovery units are connected in series, and the evaporation In the exhaust heat recovery boiler in which a transfer pump is installed between each of the evaporators and between the evaporator boilers, the cleaning liquid in the evaporator that has been cleaned is supplied to another evaporator by the transfer pump. Then, the cleaning liquid in the steam drum which has been cleaned is fed to another steam drum by the transfer pump.

  If the cleaning liquid is transferred between the exhaust heat recovery units using a transfer pump, the present invention is not limited to a vertical exhaust heat recovery boiler, and can also be applied to a horizontal exhaust heat recovery boiler. If the transfer pump is used, the transfer time can be shortened and the cleaning time can be shortened. Moreover, since a small capacity pump is sufficient for the transfer pump, power during transfer can be reduced. That is, in this aspect, the operating cost is further reduced.

  In the first aspect, the exhaust heat recovery unit may include a feed water pump for supplying boiler feed water to the economizer, and the feed water pump may be the pump of the cleaning liquid feed unit.

  In the second aspect and the third aspect, in the exhaust heat recovery boiler in which the exhaust heat recovery unit includes a feed water pump for supplying boiler feed water to the economizer, the feed water pump is connected to the exhaust heat recovery unit. A cleaning liquid may be supplied.

  In this embodiment, since the existing water supply pump is used for supplying the cleaning liquid, it is not necessary to separately install a pump for supplying the cleaning liquid. That is, according to this aspect, the equipment cost and the operation cost can be reduced.

  In the exhaust heat recovery boiler and its cleaning method of the present invention, cleaning is performed at room temperature using a cleaning liquid containing a neutral rust remover, so that a heating equipment and a preheating step for the cleaning liquid are not required. In addition, since the cleaning system is simplified and cleaning is performed by managing the amount of cleaning liquid in the steam drum, it is possible to reduce cleaning cost and cleaning time.

It is a piping system diagram of the exhaust heat recovery boiler of a 1st embodiment. It is a piping system diagram of the waste heat recovery boiler of a 2nd embodiment. It is a piping system diagram of the waste heat recovery boiler of a 3rd embodiment. It is a piping system diagram of the waste heat recovery boiler of a 4th embodiment. It is a piping system diagram of the waste heat recovery boiler of a 5th embodiment. It is a piping system diagram of the waste heat recovery boiler of a 6th embodiment. It is a piping system diagram of the waste heat recovery boiler of a 7th embodiment. It is a piping system diagram of the waste heat recovery boiler of an 8th embodiment.

[First Embodiment]
FIG. 1 is a piping system diagram of the exhaust heat recovery boiler according to the first embodiment. The exhaust heat recovery boiler 1 of the first embodiment is installed in a combined cycle power plant including a gas turbine and a steam turbine.
The exhaust heat recovery boiler 1 of the first embodiment includes a plurality of exhaust heat recovery units. Note that there may be one exhaust heat recovery unit. In the case of installing a plurality of exhaust heat recovery units, the exhaust heat recovery units generate steam having different pressures. In FIG. 1, three exhaust heat recovery units 10a to 10c are installed, and each of the above-described relatively high pressure (exhaust heat recovery unit 10a), medium pressure (exhaust heat recovery unit 10b), and low pressure (exhaust heat recovery unit 10c). Is generated.

First, the water supply system already installed in the combined cycle power plant will be described.
The exhaust heat recovery units 10a to 10c include steam drums 11a to 11c, evaporators 12a to 12c, economizers 13a to 13c, and superheaters 20a to 20c, respectively. Steam drum 11a and economizer 13a are connected by piping Lw4a-Lw4c. Steam drums 11a-11c and evaporators 12a-12c are connected by pipes Lw5-1a-Lw5-1c and Lw5-2a-Lw5-2c, respectively.

  The condenser 2 is connected to the economizer 13c of the low-pressure exhaust heat recovery unit 10c through the pipe Lw1. Condensate (water supply) discharged from the condenser 2 is supplied to the economizer 13c by a condensate pump 4 provided in the middle of the pipe Lw1. A valve V3 is installed in the pipe Lw1.

  The pipe Lw1 branches at a midway position, and the pipe Lw2 is connected. The pipe Lw2 is connected to the pipe Lw1. The economizer circulation pump 5 is installed in the middle of the pipe Lw2, and a part of the water supplied from the economizer 13c is supplied to the economizer 13c. A valve V4 is installed in the pipe Lw2 on the upstream side of the economizer circulation pump 5.

  The pipe Lw2 branches at an intermediate position on the upstream side of the valve V4, and the pipe Lw3 is connected. A valve V5 is installed in the pipe Lw3. The pipe Lw3 further branches into Lw3-1 and Lw3-2 at midway positions, and is connected to the economizers 13a and 13b, respectively. Water supply pumps 14a and 14b are installed in the middle of the pipes Lw3-1 and Lw3-2, and the water supplied from the economizer 13c is supplied to the economizers 13a and 13b. In addition, the said pump is good also as a structure which supplies a washing | cleaning liquid to piping Lw3-1 and piping Lw3-2 from one pump as an integral type.

  The steam system is configured such that the steam drums 11a to 11c are connected to the steam turbine 3 by pipes Lv1a to Lv1c in which superheaters 20a to 20c are installed on the way. In FIG. 1, the pipe Lv1b is branched on the steam downstream side of the superheater 20b, and the pipe Lv2 is connected. Steam is sent to the gas turbine (not shown) for cooling the gas turbine through the pipe Lv2.

  In FIG. 1, the pipe Lw3-1 is branched on the upstream side of the economizer 13a, and the pipe Lw6a is connected. The pipe Lw6a is connected to the superheater 20a, and is configured such that the feed water is conveyed to the superheater 20a to reduce overheating. Moreover, the pipe Lw3-2 branches on the upstream side of the economizer 13b, and the pipe Lw6b is connected. The pipe Lw6b is connected to a reheater 21 that is directed in the middle of the pipe Lv1b, and is configured such that the feed water is conveyed to the reheater 21 to reduce overheating. Valves V6 and V7 are installed in the pipes Lw6a and Lw6b, respectively.

The cleaning system (cleaning unit) of the exhaust heat recovery boiler 1 will be described below. FIG. 1 shows an example in which the economizers 13a to 13c are also cleaned.
The cleaning pipe of the first embodiment includes pipes Lc1 to Lc4, pipes Lw4a to Lw4c, pipes Lw5-1a to Lw5-1c, and pipes Lw5-2a to Lw5-2c among existing water supply systems.

  The pipe Lc1 connects the steam drum 11a and the pipe Lw3-2. The pipe Lc2 connects the steam drum 11b and the pipe Lw1. The pipe Lc3 connects the steam drum 11c and the pipe Lw3-1. The pipes Lc1 to Lc3 are connected to the steam drums at the steam drum flanges of the steam drums 11a to 11c. The steam drum has the highest device arrangement level in each of the exhaust heat recovery units 10a to 10c, and the steam drum flange is installed at the center level of the steam drum.

  When the economizers 13a to 13c are not cleaned, the pipe Lc1 is connected to the pipe Lw4b or the pipe Lw5-1b. Similarly, the pipe Lc2 is connected to the pipe Lw4c or the pipe Lw5-1c. The pipe Lc3 is connected to the pipe Lw4a or the pipe Lw5-1a.

  Valves V1 and V2 are installed in the middle of the pipe Lc3. Between the valve V1 and the valve V2, a water-filled pump 30 for circulating the cleaning liquid in the cleaning pipe is installed. The water-filled pump 30 is a plunger pump or a diaphragm pump.

  In the present embodiment, as shown in FIG. 1, no means for adjusting the temperature of the cleaning liquid is installed in the cleaning system.

  The reservoir 50 stores the cleaning liquid therein. The cleaning liquid is an aqueous solution containing a neutral rust remover. The cleaning liquid is stored in the storage unit 50 at room temperature (about room temperature, specifically 5 to 50 ° C., more preferably 15 to 30 ° C.).

A neutral rust remover is a chelating agent, a reducing agent, or a mixture of a chelating agent and a reducing agent, and an object to be removed (for example, a scale or rust that contains a metal oxide or a metal salt). Etc.) can be removed. Chelating agents include, for example, aminocarboxylic acids such as EDTA, BAPTA, DOTA, EDDS, INN, NTA, DTPA, HEDTA, TTHA, PDTA, DPTA-OH, HIDA, DHEG, GEDTA, CMGA, and EDDS, and amino such as salts thereof. Carboxylic acid chelating agents, oxycarboxylic acid chelating agents such as citric acid, gluconic acid, hydroxyacetic acid and the like, and salts thereof, organic phosphoric acids such as ATMP, HEDP, NTMP, PBTC, EDTMP and their salts Organic phosphorus chelating agents such as Examples of the reducing agent include various metal ions such as Fe ²⁺ and Sn ²⁺ , nitrites such as sodium sulfite, organic compounds such as oxalic acid, formic acid, ascorbic acid, pyrogallol, hydrazine, hydrogen, and the like. The cleaning liquid containing a neutral derusting agent has a pH of 4-8. Moreover, a corrosion inhibitor may be added to the neutral rust remover.

  In the cleaning liquid, the concentrations of the chelating agent, the reducing agent, and the corrosion inhibitor are appropriately adjusted so that a desired cleaning power and cleaning time can be obtained.

  The pipe Lc4 connects the storage unit 50 and the pipe Lc3 between the valve V1 and the water pump 30. In the middle of the pipe Lc4, a chemical injection pump 51 that supplies the cleaning liquid in the valve V8 and the reservoir 50 to the pipe Lc3 is installed.

Each of the steam drums 11a to 11c includes a measuring unit (not shown) that measures the water level in the steam drum. It is preferable that a measurement part is the steam drum flange vicinity of each steam drum 11a-11c. The steam drum flange has the highest equipment placement level among the parts to be cleaned in the exhaust heat recovery units 10a to 10c.
Alternatively, a vent pipe or a drain pipe installed in a site to be cleaned such as the evaporators 12a to 12c and the economizers 13a to 13c is used as a measurement unit, and a valve attached to the vent pipe or the drain pipe is operated to The water level may be measured by confirming the supply. Among the parts to be cleaned, the vent pipe has the highest equipment placement level, and the drain pipe has the lowest equipment placement level.

A method for cleaning the inside of the piping of the exhaust heat recovery boiler of FIG. 1 will be described below. The following cleaning may be performed only once or multiple times.
The cleaning liquid is neutral. For this reason, in this embodiment, it is not necessary to remove the SUS member before cleaning.

  At the start of cleaning, the condensate pump 4, the economizer circulation pump 5, the chemical injection pump 51, and the water supply pumps 14a and 14b are stopped. As shown in FIG. 1, the valves V1, 3 to 7 are closed, and the valves V2 and V8 are opened.

  The chemical injection pump 51 is activated, and the cleaning liquid in the reservoir 50 is supplied to the pipe Lc3 via the pipe Lc4. The water-filled pump 30 is activated, and a normal temperature cleaning liquid is supplied from the pipe Lc3 to the economizer 13a via the pipe Lw3-1, and is supplied to the steam drum 11a via the pipe Lw4a. The cleaning liquid fed to the steam drum 11a is filled into the evaporator 12a through the pipe Lw5-1a and the pipe Lw5-2a.

  When the cleaning liquid in the steam drum 11a reaches the steam drum flange, the cleaning liquid flows into the pipe Lc1. The cleaning liquid flows into the pipe Lw3-2 through the pipe Lc1. In the same manner as described above, the cleaning liquid is supplied to the economizer 13b, the steam drum 11b, and the evaporator 12b. When the cleaning liquid in the steam drum 11b reaches the steam drum flange, the cleaning liquid is supplied to the economizer 13c, the steam drum 11c, and the evaporator 12c via the pipe Lc2. When the cleaning liquid in the steam drum 11c reaches the steam drum flange, the cleaning liquid flows into the pipe Lc3. Since valve | bulb V1 is closed, the water level in each steam drum 11a-11c rises.

  The measuring unit installed in the vicinity of the steam drum flange measures the water level of the cleaning liquid in the steam drums 11a to 11c. When the water level of the cleaning liquid reaches full water in each of the steam drums 11a to 11c, the water-filled pump 30 and the chemical injection pump 51 are stopped, and the valves V2 and V8 are closed.

  When the vent pipe or the drain pipe is used as the measuring section, the measuring section determines whether or not the cleaning liquid is discharged from the vent pipe or the drain pipe. When the water is discharged, it is determined that the cleaning liquid in each of the steam drums 11a to 11c is full, the water-filled pump 30 and the chemical injection pump 51 are stopped, and the valves V2 and V8 are closed.

  By closing the valve V1 and the valve V2, the economizer, the steam drum, and the evaporator of each of the exhaust heat recovery units 10a to 10c are immersed in the cleaning liquid. In this state, it is left for a predetermined time, and soaking and cleaning is performed. The soaking time is set in consideration of the concentration of neutral derusting agent in the cleaning liquid, the concentration of reducing agent, corrosion inhibitor, etc., the number of times of cleaning, and the like.

  After a predetermined time has elapsed, the valves V1 and V2 are opened, and the water-filled pump 30 is activated. The cleaning liquid used for cleaning is discharged out of the system from a blow line (not shown) provided in the middle of the pipe Lc3.

  In the cleaning method of this embodiment, since a heater such as a heater is not provided in the cleaning system, cleaning is performed at room temperature (room temperature, specifically 5 to 50 ° C.).

  As another example of the method for cleaning the inside of the pipe of the exhaust heat recovery boiler in FIG. 1, the cleaning liquid may be circulated in the pipes Lc1 to Lc3 while being immersed in the cleaning liquid. In this case, the valves V1 and V2 are opened during the immersion and the water pump 30 is operated.

In the present embodiment, since the inside of the pipe is cleaned using a normal temperature cleaning liquid containing a neutral rust remover, there is no need to install a temperature raising equipment and a cleaning liquid preheating step is unnecessary. In addition, since a cleaning solution containing a neutral rust remover is used, it is not necessary to attach or detach accessories or devices that are vulnerable to acids such as SUS and Al parts for cleaning. Therefore, the time and cost required for cleaning are reduced.
In addition, according to the present embodiment, since a heater such as a heater is not provided in the cleaning system, cleaning is performed at room temperature. The cleaning system of the present embodiment is simple, and cleaning is performed with the amount of the chemical solution managed by the measurement unit. For this reason, the usage-amount of a washing | cleaning liquid can be restrained and washing | cleaning cost reduces. In addition, the time required for cleaning can be reduced.

[Second Embodiment]
FIG. 2 is a piping system diagram of the exhaust heat recovery boiler according to the second embodiment. In FIG. 2, the same components as those in FIG.

  The exhaust heat recovery boiler 101 of the second embodiment is also installed in the combined cycle power plant. The exhaust heat recovery boiler 101 in FIG. 2 has a plurality of exhaust heat recovery units that generate the above-described different pressures.

  The exhaust heat recovery boiler 101 of the second embodiment has the same water supply system and steam system as in FIG. 1, but the cleaning system is different. FIG. 2 shows an example in which the economizers 13a to 13c are also cleaned.

  The cleaning pipe of the second embodiment includes pipes Lc4, Lc11 to Lc15, pipes Lw3-1 and Lw3-2, pipes Lw4a to Lw4c, pipes Lw5-1a to Lw5-1c, and pipe Lw5 among the existing water supply systems. -2a to Lw5-2c.

  The reservoir 50, the pipe Lc4, the valve V8, and the chemical injection pump 51 have the same configuration as in the first embodiment. The reservoir 50 stores the cleaning liquid described in the first embodiment.

  The pipe Lc11 connects the evaporator 12a and the pipe Lw3-1. A valve V11 and a valve V14 are installed in the pipe Lc11. The water pump 30 is installed in a pipe Lc11 between the valves V11 and V14.

  A filter (not shown) is preferably installed between the valve V14 of the pipe Lc11 and the water-filled pump 30.

  A pipe Lc12 is connected to the pipe Lc11 between the water-filled pump 30 and the valve V11. One end of the pipe Lc12 is connected to the pipe Lw3-2. A valve V12 is installed in the middle of the pipe Lc12.

  The pipe Lc13 is connected to the pipe Lc12 between the connection position to the pipe Lc11 and the valve V12. One end of the pipe L13 is connected to the pipe Lw1. A valve V13 is installed in the middle of the pipe Lc13.

  The pipe Lc14 is connected to the evaporator 12b, and is connected to the pipe Lc11 between the valve V14 and the water pump 30. A valve V15 is installed in the middle of the pipe Lc14.

  The pipe Lc15 is connected to the evaporator 12c, and is connected to the pipe Lc14 between the valve V15 and the connection position to the pipe Lc11. A valve V16 is installed in the middle of the pipe Lc15.

  The pipes Lc11, Lc14, and Lc15 are preferably connected to the inlet headers of the evaporators 12a to 12c having a low equipment arrangement level. Instead of the inlet header, the pipes Lc11, Lc14, Lc15 may be connected to drum level reducing pipes or drain pipes installed in the inlet headers of the evaporators 12a to 12c.

  When the economizers 13a to 13c are not cleaned, the pipes Lc11 to Lc13 are connected to the pipes Lw4a to Lw4c or Lw5-1a to Lw5-1c located on the downstream side of the economizers 13a to 13c.

  A measurement part is installed in the steam drums 11a-11c. Or a measurement part may use the vent pipe or drain pipe installed in evaporator 12a-12c.

  In the present embodiment, no means for adjusting the temperature of the flowing liquid is installed in the middle of the pipes Lc11 to Lc15.

A method for cleaning the inside of the piping of the exhaust heat recovery boiler of FIG. 2 will be described below.
At the start of cleaning, the condensate pump 4, the economizer circulation pump 5, and the water supply pumps 14a and 14b are stopped. As shown in FIG. 2, the valves V12 to V16 are closed, and the valves V8 and V11 are opened. Further, the valves V3 to V7 are closed.

  The chemical injection pump 51 is activated, and the cleaning liquid in the reservoir 50 is supplied to the pipe Lc11 via the pipe Lc4. The water-filled pump 30 is activated, and a normal temperature cleaning liquid is fed from the pipe Lc11 to the economizer 13a and the steam drum 11a via the pipes Lw3-1 and Lw4a. The cleaning liquid fed to the steam drum 11a is filled into the evaporator 12a through the pipe Lw5-1a and the pipe Lw5-2a.

  The measuring unit installed on the steam drum 11a measures the water level of the cleaning liquid in the steam drum 11a. When the water level of the cleaning liquid reaches the full level in the steam drum 11a, the water-filled pump 30 and the chemical injection pump 51 are stopped, and the valves V8 and V11 are closed.

  When the vent pipe or the drain pipe is used as the measuring section, the measuring section determines whether or not the cleaning liquid is discharged from the vent pipe or the drain pipe. When the water is discharged, it is determined that the cleaning liquid in the steam drum 11a is full, the water-filled pump 30 and the chemical injection pump 51 are stopped, and the valves V8 and V11 are closed.

  By closing the valves V11 and V14, the economizer 13a, the steam drum 11a, and the evaporator 12a are immersed in the cleaning liquid. In this state, it is left for a predetermined time, and soaking and cleaning is performed. The soaking time is set in consideration of the concentration of the neutral rust remover in the cleaning liquid, the concentration of the rust inhibitor, the number of times of cleaning, and the like.

  After a predetermined time has elapsed, the valve V12 and the valve 14 are opened, and the water-filled pump 30 is activated. The cleaning liquid used for the cleaning is conveyed from the evaporator 12a to the economizer 13b, the steam drum 11b, and the evaporator 12b via the pipes Lc11, Lc12, Lw3-2, Lw4b, Lw5-1b, and Lw5-2b. The measuring unit measures the water level in the steam drum 11b. When the steam drum 11b does not reach full water, the chemical injection pump 51 is activated, the valve V8 is opened, and the cleaning liquid in the reservoir 50 is conveyed to the economizer 13b, the steam drum 11b, and the evaporator 12b. The filter installed in the pipe Lc11 collects solids contained in the cleaning liquid when the cleaning liquid used for cleaning is supplied to the exhaust heat recovery unit 10b.

  When the steam drum 11b reaches full water, the water-filled pump 30 and the chemical injection pump 51 are stopped, and the valves V8, V12, and V14 are closed. Thereby, the economizer 13b, the steam drum 11b, and the evaporator 12b are immersed and washed.

  The exhaust heat recovery unit 10c also performs cleaning liquid transfer and cleaning in the same process.

  The order of washing is not limited to the above, and can be performed in any order. The cleaning of each of the exhaust heat recovery units 10a to 10c may be performed once or may be performed a plurality of times.

  If washing is repeated, the washing ability of the washing solution decreases. Therefore, in the second embodiment, after a predetermined number of times of cleaning, or when the concentration of a neutral rust remover or the like is monitored by monitoring the components of the cleaning solution, or the concentration of the scale component dissolved in the cleaning solution is a predetermined value. When it exceeds, the used cleaning liquid is discharged out of the system from a blow line (not shown) provided in the middle of the pipe Lc11. After the cleaning liquid is discharged, a new cleaning liquid is supplied from the storage unit 50.

  As another method for cleaning the inside of the pipe of the exhaust heat recovery boiler of FIG. 2, the cleaning liquid may be circulated in the pipe while the inside of the pipe is immersed in the cleaning liquid. Specifically, the water-filled pump 30 operates during cleaning. The valves V11 and V14 are opened while the exhaust heat recovery unit 10a is cleaned, the valves V12 and V15 are opened while the exhaust heat recovery unit 10b is cleaned, and the valves are cleaned while the exhaust heat recovery unit 10c is cleaned. V13 and V16 are opened.

  In the cleaning method of the present embodiment, since a heater such as a heater is not provided in the cleaning system, cleaning is performed at room temperature. In the present embodiment, the water-filled pump 30 only needs to supply the cleaning liquid to each exhaust heat recovery unit. For this reason, it can be set as a pump of a capacity | capacitance smaller than 1st Embodiment, and it is possible to reduce power. Further, it is possible to reduce the volume of the cleaning liquid required for cleaning as compared with the first embodiment (about 1/3 in FIG. 2).

[Third Embodiment]
FIG. 3 is a piping system diagram of the exhaust heat recovery boiler according to the third embodiment. In FIG. 3, the same components as those in FIG.

  The exhaust heat recovery boiler 201 of the third embodiment is also installed in the combined cycle power plant. The exhaust heat recovery boiler 201 of the third embodiment is a vertical exhaust heat recovery boiler (exhaust heat recovery boiler exemplified in JP-A-11-37405). That is, in the exhaust heat recovery boiler 201, a plurality of exhaust heat recovery units that generate steam having different pressures are arranged in the vertical direction.

  The exhaust heat recovery boiler 201 of the third embodiment has the same water supply system and steam system as in FIG. 2, but the cleaning system is different. FIG. 3 shows an example in which the economizers 13a to 13c are also cleaned.

  In 3rd Embodiment, in addition to the washing piping of 2nd Embodiment, piping Lc21-Lc24 is installed. The reservoir 50, the pipe Lc4, the valve V8, and the chemical injection pump 51 have the same configuration as in the second embodiment. The reservoir 50 stores the cleaning liquid described in the first embodiment.

  The pipe Lc21 and the pipe Lc22 (first connecting pipe) connect the evaporators adjacent in the vertical direction. FIG. 3 is an example in which the evaporator 12a, the evaporator 12b, and the evaporator 12c are arranged in this order from the upper side in the vertical direction. The pipe Lc21 connects the evaporator 12a and the evaporator 12b. The pipe Lc22 connects the evaporator 12b and the evaporator 12c. The connecting positions are preferably drum level reducing pipes 60a to 60c provided at the inlet headers of the respective evaporators 12a to 12c. The evaporators 12a to 12c are connected in series with the flow of the cleaning liquid by the pipe Lc21 and the pipe Lc22.

  The pipe Lc23 and the pipe Lc24 (second connecting pipe) connect the steam drums adjacent in the vertical direction. FIG. 3 shows an example in which the steam drum 11a, the steam drum 11b, and the steam drum 11c are arranged in this order from the upper side in the vertical direction. The pipe Lc23 connects the steam drum 11a and the steam drum 11b. The pipe Lc24 connects the steam drum 11b and the steam drum 11c. The connection position is preferably the drum blow pipes 61a to 61c of the respective steam drums 11a to 11c. The steam drums 11a to 11c are connected in series with the flow of the cleaning liquid by the pipe Lc23 and the pipe Lc24.

Valves V21 to V24 are installed in the middle positions of the pipes Lc21 to Lc24, respectively.
The vertical arrangement of the evaporator and the steam drum is not limited to the above.

  A method for cleaning the inside of the piping of the exhaust heat recovery boiler of FIG. 3 will be described below. Here, a method of immersing and cleaning the inside of the pipe will be described as an example.

  At the start of cleaning, the condensate pump 4, the economizer circulation pump 5, and the water supply pumps 14a and 14b are stopped. The valves V12 to V16 and V21 to V24 are closed, and the valves V8 and V11 are opened. Further, the valves V3 to V7 are closed.

  First, as described in the second embodiment, the cleaning liquid is supplied to the exhaust heat recovery unit 10a, and the exhaust heat recovery unit 10a is cleaned.

  After cleaning the exhaust heat recovery unit 10a, the water-filled pump 30 is started and the valves V12 and V14 are opened, and the cleaning liquid is conveyed to the economizer 13b, the steam drum 11b, and the evaporator 12b via the pipes Lc11 and Lc12. .

  The evaporator 12a is disposed at a higher position than the evaporator 12b. The steam drum 11a is disposed at a position higher than the steam drum 11b. After the cleaning of the exhaust heat recovery unit 10a, when the valves V21 and V23 are opened, the cleaning liquid is conveyed to the evaporator 12b and the steam drum 11b through the pipes Lc21 and Lc23 by gravity. When the water level in the steam drum 11b measured by the measurement unit does not reach full water, the chemical injection pump 51 is activated, the valve V8 is opened, and the cleaning liquid in the storage unit 50 is stored in the economizer 13b, the steam drum 11b, and It is conveyed to the evaporator 12b. The filter installed in the pipe Lc11 collects solids contained in the cleaning liquid when the cleaning liquid used for cleaning is supplied to the exhaust heat recovery unit 10b.

  When the steam drum 11b reaches full water, the water-filled pump 30 and the chemical injection pump 51 are stopped, and the valves V8, V12, V14, V21, and V23 are closed. Thereby, the economizer 13b, the steam drum 11b, and the evaporator 12b are immersed and washed.

  The exhaust heat recovery unit 10c also performs cleaning liquid transfer and cleaning in the same process. Washing can be performed in any order. The cleaning of each of the exhaust heat recovery units 10a to 10c may be performed once or may be performed a plurality of times.

  Even in the third embodiment, the water-tight pump 30 may be operated while the inside of the pipe is immersed in the cleaning liquid, and the cleaning liquid may be circulated in the pipe.

  The cleaning method of the present embodiment can reduce the time required to transfer the cleaning liquid as compared with the second embodiment, and can shorten the cleaning time. In addition, the volume of the water-filled pump 30 can be further reduced, and the power required for transferring the cleaning liquid can be reduced.

[Fourth Embodiment]
FIG. 4 is a piping system diagram of the exhaust heat recovery boiler according to the fourth embodiment. 4, the same components as those in FIG. 3 are denoted by the same reference numerals.

  The exhaust heat recovery boiler 301 of the fourth embodiment is not limited to a vertical type, and can be applied to a horizontal type. The exhaust heat recovery boiler 301 of the fourth embodiment differs from the third embodiment in that no valves are installed in the pipes Lc21 to Lc24 and transfer pumps 71a to 71d are installed. In the fourth embodiment, regarding the connection of the pipes Lc21 to Lc24, it is not necessary to consider the vertical arrangement of the evaporators and the steam drums even in a vertical exhaust heat recovery boiler.

  The cleaning method using the exhaust heat recovery boiler 301 of the fourth embodiment is different from the third embodiment with respect to the transfer of the cleaning liquid. In the fourth embodiment, the transfer pumps 71a and 71c are activated after the exhaust heat recovery unit 10a is cleaned. Thereby, the cleaning liquid inside the evaporator 12a is conveyed to the evaporator 12b via the pipe Lc21, and the cleaning liquid inside the vapor drum 11a is conveyed to the vapor drum 11b via the pipe Lc23. In addition, the water pump 30 is activated and the valves V12 and V14 are opened, and the cleaning liquid is conveyed to the economizer 13b, the steam drum 11b, and the evaporator 12b via the pipes Lc11 and Lc12. When the water level in the steam drum 11b measured by the measurement unit does not reach full water, the chemical injection pump 51 is activated, the valve V8 is opened, and the cleaning liquid in the storage unit 50 is stored in the economizer 13b, the steam drum 11b, and It is conveyed to the evaporator 12b. When the steam drum 11b reaches full water, the transfer pumps 71a and 71c, the water pump 30 and the medicine pump 51 are stopped, and the valves V8, V12 and V14 are closed. Thereby, the economizer 13b, the steam drum 11b, and the evaporator 12b are immersed and washed. The exhaust heat recovery unit 10c also performs cleaning liquid transfer and cleaning in the same process.

  Also in the fourth embodiment, the cleaning liquid may be circulated in the pipe while the pipe is immersed in the cleaning liquid.

  Compared with the second and third embodiments, the cleaning method of the present embodiment can reduce the time required to transfer the cleaning liquid and can reduce the cleaning time. Further, it is possible to further reduce the volume of the water-filled pump 30 as compared with the second embodiment and also reduce the power required for transferring the cleaning liquid.

  In the first to fourth embodiments, the cleaning liquid is controlled by controlling the operation cycle of the water-filled pump (plunger pump or diaphragm pump) 30 during the supply and transfer of the cleaning liquid or during the circulation of the cleaning liquid during the cleaning. It is also possible to give strength to the flow (by changing the flow rate in a short cycle). By doing so, it is possible to improve the cleaning effect.

  In the plunger pump and the diaphragm pump, the cleaning liquid is not supplied from the water-filled pump 30 when the cleaning liquid is sucked in the operation. Therefore, in the exhaust heat recovery boilers of the first to fourth embodiments, an automatic valve (not shown in FIGS. 1 to 4) is provided in the cleaning pipe. This automatic valve is linked to the operation of the plunger pump or diaphragm pump. The automatic valve extracts the cleaning liquid from the cleaning pipe, and supplies the cleaning liquid extracted in the direction opposite to the flow direction of the cleaning liquid at a timing when the water-filled pump 30 does not supply the cleaning liquid. By providing such an automatic valve, it is possible to improve the cleaning effect.

  In the first to fourth embodiments, a spiral groove may be formed inside the cleaning pipe. The cleaning liquid flows through the cleaning pipe and each device while being stirred by the spiral groove. Or the stirring apparatus may be installed in the middle position of the washing piping of the first to fourth embodiments. By adopting such a configuration, it is possible to improve the cleaning effect.

[Fifth Embodiment]
FIG. 5 is a piping system diagram of the exhaust heat recovery boiler according to the fifth embodiment. In FIG. 5, the same components as those in FIG.

  The exhaust heat recovery boiler 401 of the fifth embodiment is also installed in the combined cycle power plant. The exhaust heat recovery boiler 401 in FIG. 5 includes a plurality of exhaust heat recovery units that generate the above-described different pressures.

  The exhaust heat recovery boiler 401 of the fifth embodiment has the same water supply system and steam system as in FIG. 1, but the cleaning system is different. FIG. 5 shows an example in which the economizers 13a to 13c are also cleaned.

  The cleaning pipes of the fifth embodiment include pipes Lc4, Lc31 to Lc33 and pipes Lw1 to Lw3, Lw3-1, Lw3-2, Lw4a to Lw4c, Lw5-1a to Lw5-1c, Lw5 among the existing water supply systems. -2a to Lw5-2c.

  The reservoir 50 stores the same cleaning liquid as in the first embodiment.

  The pipe Lc31 connects the evaporator 12a and the pipe Lw2. The connection position in the pipe Lw2 is between the valve V4 and the economizer circulation pump 5. Valves V31 and V32 are installed in the middle of the pipe Lc31. The pipe Lc4 is connected to the pipe Lc31 between the valves V31 and V32.

  The pipe Lc32 connects the pipe Lc31 between the valves V31 and V32 and the evaporator 12b. A valve V33 is installed in the middle of the pipe Lc32.

  The pipe Lc33 connects the pipe Lc32 and the evaporator 12c. The connection position with the pipe Lc32 is between the position where the pipe Lc32 is connected to the pipe Lc31 and the valve V33. A valve V34 is installed in the middle of the pipe Lc33.

  In the fifth embodiment, the water-filled pump is not installed as in the first to fourth embodiments. Further, no means for adjusting the temperature of the cleaning liquid is installed in the cleaning system.

A method for cleaning the inside of the piping of the exhaust heat recovery boiler 401 in FIG. 5 will be described below.
At the start of cleaning, the condensate pump 4, the economizer circulation pump 5, the chemical injection pump 51, and the water supply pumps 14a and 14b are stopped. As shown in FIG. 5, the valves V3, V4, V6, V7, V31, 33, 34 are closed, and the valves V5, V8, V32 are opened.

  The chemical injection pump 51 is activated, and the cleaning liquid in the reservoir 50 is supplied to the pipe Lc31 via the pipe Lc4. The economizer circulation pump 5 is activated, and a normal temperature cleaning liquid is supplied from the pipe Lc31 to the economizer 13c. A part of the cleaning liquid supplied to the economizer 13c is supplied to the steam drum 11c and the evaporator 12c via the pipes Lw4c, L5-1wc, and Lw5-2c. The remainder of the cleaning liquid supplied to the economizer 13c is supplied to the exhaust heat recovery unit 10a via the pipes Lw2, Lw3, Lw3-1, Lw4a, Lw5-1a, and Lw5-2a. The cleaning liquid is supplied to the exhaust heat recovery unit 10b through the pipes Lw2, Lw3, Lw3-2, Lw4b, Lw5-1b, and Lw5-2b.

  When the economizer circulation pump 5 is not present or cannot be used, the pipe Lc4 connecting the reservoir 50, the valve V8 and the chemical injection pump 51, and the condenser 2 or the condenser 2 and the condensate pump 4 are connected. A pipe connecting the pipe Lw1 is installed. And the condensate pump 4 is started, valve | bulb V3 is open | released, and wash water is supplied to each waste-heat-recovery parts 10a-10c by the condensate pump 4. FIG.

  The measurement unit measures the water level of the cleaning liquid in the steam drums 11a to 11c. When the water level of the cleaning liquid reaches full water in each of the steam drums 11a to 11c, the economizer circulation pump 5 and the chemical injection pump 51 are stopped, and the valve V32 is closed. Thereby, cleaning of the economizer, the steam drum and the evaporator of the exhaust heat recovery units 10a to 10c is started.

  After a predetermined time elapses, the valves V5, V31 to V34 are opened, and the economizer circulation pump 5 is activated. The cleaning liquid used for cleaning is discharged out of the system from a blow line (not shown) provided in the middle of the pipe Lc31.

  In the cleaning method of the present embodiment, since a heater such as a heater is not provided in the cleaning system, cleaning is performed at room temperature. In the present embodiment, the cleaning liquid is supplied by using the economizer circulation pump 5 (or the condensate pump 4 in some cases) for supplying boiler feedwater to the economizer. That is, since the water supply pump of the existing water supply system is also used for cleaning, it is possible to reduce facility installation costs and operation costs.

[Sixth Embodiment]
FIG. 6 is a piping system diagram of the exhaust heat recovery boiler according to the sixth embodiment. In FIG. 6, the same components as those in FIG.

  The exhaust heat recovery boiler 501 of the sixth embodiment is different from the fifth embodiment in that the pipes Lc41 to Lc43 are installed. The pipe Lc41 connects the pipe Lw3-1 and the evaporator 12a between the water supply pump 14a and the economizer 13a. The pipe Lc42 connects the pipe Lw3-2 and the evaporator 12b between the water supply pump 14b and the economizer 13b. The pipe Lc43 connects the pipe Lw1 on the upstream side of the economizer 13c and the evaporator 12c.

  In the sixth embodiment, no water-filled pump is installed as in the first to fourth embodiments. Further, no means for adjusting the temperature of the cleaning liquid is installed in the cleaning system.

A method for cleaning the inside of the pipe of the exhaust heat recovery boiler 501 in FIG. 6 will be described below.
At the start of cleaning, the condensate pump 4, the economizer circulation pump 5, the chemical injection pump 51, and the water supply pumps 14a and 14b are stopped. As shown in FIG. 6, the valves V3, V4, V6, and V7 are closed, and the valves V5, V8, and V31 to V34 are opened.

  The medicinal pump 51 is activated, and the cleaning liquid in the storage unit 50 is supplied to the exhaust heat recovery units 10a to 10c through the route described in the fifth embodiment. In the present embodiment, the cleaning liquid is further supplied to the evaporators 12a to 12c through the pipes Lc41 to Lc43.

  The measurement unit measures the water level of the cleaning liquid in the steam drums 11a to 11c. When the water level of the cleaning liquid reaches full water in each of the steam drums 11a to 11c, the valve V8 is closed and the chemical injection pump 51 is stopped. In the present embodiment, the economizer circulation pump 5 and the water supply pumps 14a and 14b are not stopped. For this reason, the economizer, the steam drum and the evaporator are immersed in the cleaning liquid and cleaned while the cleaning liquid is circulated. The circulation amount at this time is preferably the minimum flow of each pump (about 25% to 30% of the pump rated capacity).

  After a predetermined time has elapsed, the cleaning liquid is discharged out of the system from a blow line (not shown) provided in the middle of the pipe Lc31.

  In the present embodiment, the cleaning is performed while circulating the cleaning liquid, so that the removal rate of scale and the like is improved.

[Seventh Embodiment]
FIG. 7 is a piping system diagram of an exhaust heat recovery boiler according to the seventh embodiment. In FIG. 7, the same components as those in FIG.

  In the exhaust heat recovery boiler 601 of the seventh embodiment, the fifth implementation is that a pipe Lc51 that connects the pipe Lc31 and the pipe Lw3-1 and a pipe Lc52 that connects the pipe Lc31 and the pipe Lw3 are installed. Different from form. The pipe Lc52 may be connected to the pipe Lw3-2. Valves V51 and V52 are installed in the pipes Lc51 and Lc52, respectively.

  In the seventh embodiment, the water-filled pump is not installed as in the first to fourth embodiments. Further, no means for adjusting the temperature of the cleaning liquid is installed in the cleaning system.

A method for cleaning the inside of the piping of the exhaust heat recovery boiler 601 in FIG. 7 will be described below.
At the start of cleaning, the condensate pump 4, the economizer circulation pump 5, the chemical injection pump 51, and the water supply pumps 14a and 14b are stopped. As shown in FIG. 5, the valves V3 to V7, V31 to 34, and V52 are closed, and the valves V8 and V51 are opened.

  The chemical injection pump 51 is activated, and the cleaning liquid in the reservoir 50 is supplied to the pipe Lc31 via the pipe Lc4. The water supply pump 14a is activated, and a normal temperature cleaning liquid is supplied from the pipe Lc31 to the economizer 13a through the pipe Lw3-1. The cleaning liquid supplied to the economizer 13a is supplied to the steam drum 11a and the evaporator 12a via the pipes Lw4a, Lw5-1a, and Lw5-2a.

  The measuring unit measures the water level of the cleaning liquid in the steam drum 11a. When the water level of the cleaning liquid reaches the full level in the steam drum 11a, the water supply pump 14a and the chemical injection pump 51 are stopped, and the valves V8 and V51 are closed. Thereby, washing | cleaning of the economizer 13a, the steam drum 11a, and the evaporator 12a is started.

  After a predetermined time has elapsed, the valves V31 and V52 are opened, and the water supply pump 14b is activated. The cleaning liquid used for cleaning the exhaust heat recovery unit 10a is supplied to the economizer 13b through the pipes Lc31, Lc52, and Lw3-2. Then, it is fed to the steam drum 11b and the evaporator 12b via the pipes Lw4b, Lw5-1b, and Lw5-2b. The measuring unit measures the water level in the steam drum 11b. When the steam drum 11b does not reach full water, the chemical injection pump 51 is activated, the valve V8 is opened, and the cleaning liquid in the reservoir 50 is conveyed to the economizer 13b, the steam drum 11b, and the evaporator 12b.

  When the steam drum 11b reaches full water, the feed water pump 14b and the medicine pump 51 are stopped, and the valves V8, V31, and V52 are closed. Thereby, the economizer 13b, the steam drum 11b, and the evaporator 12b are immersed and washed.

  After a predetermined time has elapsed, the valves V32 and V33 are opened, and the economizer circulation pump 5 is activated. The cleaning liquid used for cleaning the exhaust heat recovery unit 10b is supplied to the economizer 13c via Lc32, Lc31, and Lw1. Then, it is fed to the steam drum 11c and the evaporator 12c through the pipes Lw4c, Lw5-1c, and Lw5-2c. The measuring unit measures the water level in the steam drum 11c. When the steam drum 11c does not reach full water, the chemical injection pump 51 is activated, the valve V8 is opened, and the cleaning liquid in the reservoir 50 is conveyed to the economizer 13c, the steam drum 11c, and the evaporator 12c.

  When the steam drum 11c reaches full water, the economizer circulation pump 5 and the chemical injection pump 51 are stopped, and the valves V8, V32, and V33 are closed. Thereby, the economizer 13c, the steam drum 11c, and the evaporator 12c are immersed and washed.

  The order of washing is not limited to the above, and can be performed in any order. The cleaning of each of the exhaust heat recovery units 10a to 10c may be performed once or may be performed a plurality of times. Also, the cleaning liquid used for the predetermined number of times of cleaning is discharged out of the system from a blow line (not shown) provided in the middle of the pipe Lc31. After the cleaning liquid is discharged, a new cleaning liquid is supplied from the storage unit 50.

  In the cleaning method of the present embodiment, since a heater such as a heater is not provided in the cleaning system, cleaning is performed at room temperature. Compared with the fifth embodiment, the volume of the cleaning liquid required for cleaning can be reduced. In the present embodiment, the cleaning liquid is supplied by using the water supply pumps 14 a and 14 b that supply water to the economizer and the economizer circulation pump 5. That is, since the pump of the existing water supply system is also used for cleaning, it is possible to reduce facility installation costs and operation costs.

  In the modification of the present embodiment, as described in the third embodiment, a vertical exhaust heat recovery boiler is provided with a pipe that connects the vertically adjacent evaporator boiler and the evaporator in series. Also good. In this modification, the cleaning liquid is transferred using gravity through the above-described piping after cleaning. For this reason, it is possible to shorten the cleaning time.

  In another modification of the present embodiment, as described in the fourth embodiment, a piping that connects the evaporation boiler and the evaporator in series and a transfer pump are installed. In this modification, a pump is used to transfer the cleaning liquid, so that the cleaning time can be shortened.

[Eighth Embodiment]
FIG. 8 is a piping diagram of the exhaust heat recovery boiler according to the eighth embodiment. 8, the same components as those in FIGS. 6 and 7 are denoted by the same reference numerals.

  The exhaust heat recovery boiler 701 of the eighth embodiment differs from the sixth embodiment in that the pipes Lc51 and Lc52 are installed as in the seventh embodiment.

  In the eighth embodiment, no water-filled pump is installed as in the first to fourth embodiments. Further, no means for adjusting the temperature of the cleaning liquid is installed in the cleaning system.

A method for cleaning the inside of the piping of the exhaust heat recovery boiler 701 in FIG. 8 will be described below.
At the start of cleaning, the condensate pump 4, the economizer circulation pump 5, the chemical injection pump 51, and the water supply pumps 14a and 14b are stopped. As shown in FIG. 8, the valves V3 to V7, V32 to 34, and V52 are closed, and the valves V8, V31, and V51 are opened.

  The chemical injection pump 51 is activated, and the cleaning liquid in the reservoir 50 is supplied to the pipe Lc31 via the pipe Lc4. The water supply pump 14a is activated, and a room temperature cleaning liquid is supplied from the pipe Lc31 to the economizer 13a through the pipes Lc51 and Lw3-1. The cleaning liquid supplied to the economizer 13a is supplied to the steam drum 11a and the evaporator 12a via the pipes Lw4a, Lw5-1a, Lw5-2a, and Lc41.

  The measuring unit measures the water level of the cleaning liquid in the steam drum 11a. When the water level of the cleaning liquid reaches the full level on the steam drum 11a, the valve V8 is closed and the chemical injection pump 51 is stopped. Cleaning of the economizer 13a, the steam drum 11a, and the evaporator 12a is started in a state where the feed water pump 14a is activated.

  After a predetermined time has elapsed, the valve V51 is closed and the valve V52 is opened. The feed water pump 14a is stopped and the feed water pump 14b is started. The cleaning liquid used for cleaning the exhaust heat recovery unit 10a is supplied to the economizer 13b through the pipes Lc31, Lc52, and Lw3-2. Then, it is fed to the steam drum 11b and the evaporator 12b through the pipes Lw4b, Lw5-1b, Lw5-2b, and Lc42. The measuring unit measures the water level in the steam drum 11b. When the steam drum 11b does not reach full water, the chemical injection pump 51 is activated, the valve V8 is opened, and the cleaning liquid in the reservoir 50 is conveyed to the economizer 13b, the steam drum 11b, and the evaporator 12b.

  When the steam drum 11b reaches full water, the valves V8 and V31 are closed and the medicine pump 51 is stopped. Cleaning of the economizer 13b, the steam drum 11b, and the evaporator 12b is started in a state where the feed pump 14b is activated.

  After a predetermined time has elapsed, the valve V52 is closed, the valves V32 and V34 are opened, and the economizer circulation pump 5 is activated. The cleaning liquid used for cleaning the exhaust heat recovery unit 10b is supplied to the economizer 13c via Lc32, Lc31, and Lw2. Then, it is fed to the steam drum 11c and the evaporator 12c through the pipes Lw4c, Lw5-1c, Lw5-2c, and Lc43. The measuring unit measures the water level in the steam drum 11c. When the steam drum 11c does not reach full water, the chemical injection pump 51 is activated, the valve V8 is opened, and the cleaning liquid in the reservoir 50 is conveyed to the economizer 13c, the steam drum 11c, and the evaporator 12c.

  When the steam drum 11c reaches full water, the valves V8 and V33 are closed and the medicine pump 51 is stopped. With the economizer circulation pump 5 activated, cleaning of the economizer 13c, the steam drum 11c, and the evaporator 12c is started.

  The order of washing is not limited to the above, and can be performed in any order. The cleaning of each of the exhaust heat recovery units 10a to 10c may be performed once or may be performed a plurality of times. Also, the cleaning liquid used for the predetermined number of times of cleaning is discharged out of the system from a blow line (not shown) provided in the middle of the pipe Lc31. After the cleaning liquid is discharged, a new cleaning liquid is supplied from the storage unit 50.

  In the cleaning method of the present embodiment, since a heater such as a heater is not provided in the cleaning system, cleaning is performed at room temperature. Compared with the seventh embodiment, the volume of the cleaning liquid required for cleaning can be reduced. Moreover, since the pump of the existing water supply system is utilized also for washing | cleaning in this embodiment, it is possible to reduce installation cost and operation cost.

  In the modification of the present embodiment, as described in the third embodiment, a vertical exhaust heat recovery boiler is provided with a pipe that connects the vertically adjacent evaporator boiler and the evaporator in series. Also good. In another modification of the present embodiment, as described in the fourth embodiment, a pipe that connects the evaporation boiler and the evaporator in series and a transfer pump may be installed.

1, 101, 201, 301, 401, 501, 601, 701 Exhaust heat recovery boiler 2 Condenser 3 Steam turbine 4 Condensate pump 5 Conservator circulation pumps 10a to 10c Exhaust heat recovery units 11a to 11c Steam drum 12a to 12c Evaporators 13a to 13c Energy-saving devices 14a and 14b Water supply pumps 20a to 20c Superheater 21 Reheater 30 Water-filled pump 50 Reservoir 51 Chemical injection pump 60 Drum level reduction pipe 61 Drum blow pipes 71a to 71d Transfer pump

Claims (18)

An exhaust heat recovery boiler comprising an exhaust heat recovery unit having an evaporator, a steam drum, and a economizer,
A cleaning unit for cleaning the exhaust heat recovery unit;
The cleaning unit
A storage unit for storing a normal temperature cleaning liquid containing a neutral rust remover, a cleaning pipe for guiding the cleaning liquid to the exhaust heat recovery unit and exhausting the cleaning liquid from the exhaust heat recovery unit, and circulating the cleaning liquid through the cleaning pipe A cleaning liquid supply unit including a pump;
A measuring unit for measuring the water level of the cleaning liquid in the steam drum;
An exhaust heat recovery boiler provided with a valve that is provided at an intermediate position of the cleaning pipe and adjusts to a predetermined water level of the cleaning liquid at room temperature in the steam drum based on a measurement value of the measurement unit.   The exhaust heat recovery boiler according to claim 1, wherein the cleaning pipe guides the cleaning liquid to the economizer. A plurality of exhaust heat recovery units that generate steam having different pressures, the cleaning liquid supply unit is connected to the exhaust heat recovery unit on the most upstream side of the cleaning liquid, and a communication pipe includes the plurality of exhaust heat recovery units. Connected in series, the cleaning pipe is connected to the exhaust heat recovery section on the most downstream side of the cleaning liquid,
The exhaust heat recovery boiler according to claim 1 or 2, wherein the pump supplies the cleaning liquid to all the exhaust heat recovery units in one cleaning. A plurality of exhaust heat recovery units that generate steam having different pressures, and the cleaning pipe is connected in parallel to each of the plurality of exhaust heat recovery units;
The exhaust heat recovery boiler according to claim 1 or 2, wherein the pump supplies the cleaning liquid to all the exhaust heat recovery units in one cleaning. A plurality of exhaust heat recovery units that generate steam having different pressures, and the cleaning pipe is connected to each of the plurality of exhaust heat recovery units;
The exhaust heat recovery boiler according to claim 1 or 2, wherein the pump supplies the cleaning liquid from the storage unit to one exhaust heat recovery unit in one cleaning. The plurality of exhaust heat recovery units are arranged in a vertical direction,
The first connecting pipe connects the evaporators adjacent in the vertical direction in series, the second connecting pipe connects the steam drums adjacent in the vertical direction in series,
The cleaning liquid in the evaporator that has been cleaned is fed by gravity to the evaporator located below the cleaned evaporator through the first connecting pipe,
The cleaning liquid in the steam drum that has been cleaned is fed by gravity to the steam drum located below the steam drum that has been cleaned through the second connecting pipe. 5. An exhaust heat recovery boiler according to 5. A first communication pipe connects the evaporators of the plurality of exhaust heat recovery units in series, a second communication pipe connects the steam drums of the plurality of exhaust heat recovery units in series, and the first communication pipes A transfer pump is installed in each of the communication pipe and the second communication pipe;
The transfer pump supplies the cleaning liquid in the evaporator, which has been cleaned, to another evaporator via the first communication pipe, and the cleaning drum in the steam drum in which the cleaning has been performed. The exhaust heat recovery boiler according to claim 5, wherein the cleaning liquid is supplied to another steam drum through the second communication pipe.   The said waste heat recovery part is provided with the feed water pump for supplying boiler feed water to the said economizer, and the said feed water pump is the said pump of the said washing | cleaning liquid supply part. Waste heat recovery boiler. In the exhaust heat recovery boiler including an exhaust heat recovery unit having an evaporator, a steam drum, and a economizer, a cleaning method for cleaning the exhaust heat recovery unit,
A room temperature cleaning liquid containing a neutral rust remover is supplied to the exhaust heat recovery unit until the steam drum is filled with the cleaning liquid,
After the steam drum is filled with the cleaning liquid, the supply of the cleaning liquid to the exhaust heat recovery unit is stopped, and the interior of the exhaust heat recovery unit is immersed in the cleaning liquid at room temperature for a predetermined time,
A cleaning method in which the cleaning liquid is discharged from the exhaust heat recovery unit that has been cleaned after the predetermined time has elapsed. In the exhaust heat recovery boiler including an exhaust heat recovery unit having an evaporator, a steam drum, and a economizer, a cleaning method for cleaning the exhaust heat recovery unit,
A room temperature cleaning liquid containing a neutral rust remover is supplied to the exhaust heat recovery unit until the steam drum is filled with the cleaning liquid,
After the steam drum is filled with the cleaning liquid, the inside of the exhaust heat recovery unit is immersed in the cleaning liquid at room temperature for a predetermined time while circulating the cleaning liquid in the exhaust heat recovery unit,
A cleaning method in which the cleaning liquid is discharged from the exhaust heat recovery unit that has been cleaned after the predetermined time has elapsed.   11. The inside of the exhaust heat recovery unit is washed with the cleaning liquid when the method for treating water flowing through the exhaust heat recovery unit is changed from phosphate water treatment to high-AVT water treatment. Cleaning method.   The cleaning method according to claim 9, wherein the cleaning liquid is supplied to the economizer and the inside of the economizer is immersed in the cleaning liquid.   In the exhaust heat recovery boiler, which includes a plurality of the exhaust heat recovery units that generate steam having different pressures, and wherein the plurality of exhaust heat recovery units are connected in series to the flow of the cleaning liquid, the cleaning liquid can be washed once. The cleaning method according to claim 9, wherein the cleaning method is supplied to the plurality of exhaust heat recovery units. In the exhaust heat recovery boiler comprising a plurality of the exhaust heat recovery units that generate steam having different pressures, wherein the plurality of exhaust heat recovery units are connected in parallel to the flow of the cleaning liquid,
The cleaning method according to any one of claims 9 to 12, wherein the cleaning liquid is supplied to the plurality of exhaust heat recovery units in one cleaning. In the exhaust heat recovery boiler comprising a plurality of the exhaust heat recovery units that generate steam having different pressures, wherein the plurality of exhaust heat recovery units are connected in parallel to the flow of the cleaning liquid,
The cleaning method according to any one of claims 9 to 12, wherein the cleaning liquid is supplied to one exhaust heat recovery unit in one cleaning. In the exhaust heat recovery boiler in which the plurality of exhaust heat recovery units are arranged in the vertical direction,
The cleaning liquid in the evaporator that has been cleaned is fed by gravity to the adjacent evaporator below the cleaned evaporator,
The cleaning method according to claim 15, wherein the cleaning liquid in the steam drum that has been cleaned is fed by gravity to the adjacent steam drum below the steam drum on which the cleaning has been performed. The evaporators of the plurality of exhaust heat recovery units are connected in series, the steam drums of the plurality of exhaust heat recovery units are connected in series, and a transfer pump between each of the evaporators and between the evaporation boilers In the exhaust heat recovery boiler where
The cleaning liquid in the evaporator that has been cleaned is fed to another evaporator by the transfer pump,
The cleaning method according to claim 15, wherein the cleaning liquid in the steam drum that has been cleaned is supplied to another steam drum by the transfer pump.   18. The exhaust heat recovery boiler, wherein the exhaust heat recovery unit includes a feed water pump for supplying boiler feed water to the economizer, and the feed water pump supplies the cleaning liquid to the exhaust heat recovery unit. The cleaning method according to any one of the above.

Images