JP2020153628A - Waste heat recovery boiler and temperature control method of heat transfer pipe of the same - Google Patents

Abstract

To provide a waste heat recovery boiler which can inhibit corrosion of a heat transfer pipe.SOLUTION: A waste heat recovery boiler 100 according to the present invention includes: a duct 120; a heat transfer pipe 320 having a water inlet 322 and a water outlet 324 and disposed in the duct 120; a water supply pipeline 400 connected to the water inlet 322 and having a first pipeline 420 and a second pipeline 440 which branches from the first pipeline 420 and joins the first pipeline 420 again; a tank 160 which is in fluid communication with the water outlet 324 and in which at least a part of the second pipeline 440 is disposed; a water amount adjustment valve 500 which adjusts a ratio of a flow rate of water flowing in the first pipeline 420 to a flow rate of water flowing in the second pipeline 440; a measurement device 600 which measures a corrosion rate of an interior of the duct 120; and a control device 800 which adjusts the water amount adjustment valve 500 according to a result of the measurement.SELECTED DRAWING: Figure 2

Description

The present invention relates to an exhaust heat recovery boiler and a method for controlling the temperature of a heat transfer tube of the exhaust heat recovery boiler.

The exhaust heat recovery boiler is provided with heat exchangers such as a superheater, an evaporator, and an economizer (economizer) that recover heat, and contains a heat transfer tube. High-temperature exhaust gas is supplied from the upstream side of the exhaust heat recovery boiler duct, and heat exchange is performed when the heat transfer pipe and the exhaust gas come into contact with each other. The exhaust gas, sulfur oxides produced by the combustion (SOx) and contains water vapor _(H 2 O), _etc. are. Some of the sulfur oxides react with water vapor to produce sulfuric acid (H ₂ SO ₄ ). Therefore, when the surface temperature of the heat transfer tube through which heat exchange is performed becomes lower than the dew point of sulfuric acid, the sulfuric acid condenses on the surface of the heat transfer tube, and the corrosion rate on the surface of the heat transfer tube is remarkably increased to form the heat transfer tube. The steel material is significantly corroded. In addition, the exhaust gas generated from the municipal waste incinerator contains a large amount of chloride such as hydrogen chloride (HCl), and even when the dew point of hydrogen chloride is below the dew point, the heat transfer tube is similarly corroded. .. Further, chlorides containing alkali metals and heavy metals adhere to the heat transfer surface, and the heat transfer tube is corroded by the deliquescent and melting of the chlorides. For this reason, in a boiler in which the heat transfer tube and the exhaust gas come into contact with each other, there is a concern about trouble due to corrosion, and a method of suppressing corrosion has been considered. For example, Patent Document 1 describes a boiler in which the corrosion rate is controlled.

The boiler described in Patent Document 1 includes a probe for monitoring dew point corrosion, an exhaust gas duct, and an economizer. In addition, this economizer includes a heat transfer tube arranged in the exhaust gas duct, an economizer temperature control device that controls the water supply to the heat transfer tube to adjust the temperature of the heat transfer tube, and a system control device that controls the economizer. It is provided.
The dew point corrosion monitoring probe is located close to the heat transfer tube of the economizer, and the boiler measures the corrosion rate using the dew point corrosion monitoring probe. Then, the system control device determines the operating target temperature from the measurement data of the corrosion rate so that the corrosion rate has a practically acceptable value. After that, the temperature of the heat transfer tube of the economizer is controlled so as to reach the operating target temperature. As this control method, either a method of adjusting the amount of heat generated in the boiler or a method of adjusting the amount of cooling water flowing through the heat transfer tube of the economizer, which is controlled by the economizer temperature control device, is adopted. This allows the boiler to protect the heat transfer tube from corrosion.

Japanese Unexamined Patent Publication No. 2006-258603

As described above, in the boiler described in Patent Document 1, the temperature of the heat transfer tube is adjusted by adjusting the amount of heat generated by the boiler or flowing through the heat transfer tube so that the corrosion rate of the heat transfer tube becomes a practically acceptable value. It is adjusted by adjusting the amount of cooling water.
However, when an exhaust heat recovery boiler equipped with a heat transfer tube is used in a waste treatment facility, it may not be possible to increase the amount of waste to be burned because the amount of waste to be treated is determined. In addition, since a wide variety of waste is incinerated, it is difficult to adjust the amount of heat generated from the waste, the temperature of the exhaust gas, and the components. In this case, the amount of heat generated by the boiler cannot be increased, and corrosion of the heat transfer tube cannot be suppressed.
Further, the temperature of the water flowing inside the heat transfer tube has a stronger influence on the surface temperature of the heat transfer tube than the temperature of the exhaust gas in contact with the surface of the heat transfer tube. Therefore, even if the amount of water flowing inside the heat transfer tube is reduced, the surface temperature of the heat transfer tube cannot be significantly increased if the temperature of the water remains constant. Therefore, although adjusting the amount of water flowing through the heat transfer tube has a certain effect, the temperature of the heat transfer tube cannot be significantly increased. Therefore, when a method of adjusting the amount of cooling water flowing through the heat transfer tube is adopted, it may be difficult to raise the surface temperature of the heat transfer tube to a temperature at which the corrosion rate does not pose a practical problem. In this case, corrosion of the heat transfer tube cannot be suppressed.
Therefore, an object of the present invention is to prevent corrosion of the heat transfer tube without adjusting the amount of heat generated in the boiler or the amount of water flowing through the heat transfer tube in view of the above-mentioned problems. It is to provide the control method of the heat recovery boiler and the exhaust heat recovery boiler.

(Form 1)
The exhaust heat recovery boiler according to the first embodiment has a duct having a flow path through which exhaust gas flows, a water inlet and a water outlet, a heat transfer pipe arranged inside the duct, and the water inlet of the heat transfer pipe. A water supply pipe connected to, a merging portion located on the downstream side of the diverging portion, a first pipe forming between the diverging portion and the merging portion, and the first pipe. A second pipe that branches at the diversion portion and merges with the first pipe again at the confluence portion, and supplies water that has passed through the confluence portion to the water inlet of the heat transfer pipe. A tank that is fluidly communicated with the supply pipe and the water outlet of the heat transfer pipe and at least a part of the second pipe is arranged inside, and the flow rate of water flowing through the first pipe and flowing through the second pipe. A water amount adjusting valve that adjusts the ratio with the flow rate of water, a measuring device that measures at least one of the corrosion rate, temperature, and exhaust gas component inside the duct, and the measurement device according to the measurement result of the measuring device. It is provided with a control device for adjusting and controlling the water amount adjusting valve.
In the exhaust heat recovery boiler according to the first aspect, water or steam that has passed through the heat transfer tube and has become hot flows into the tank. Since at least a part of the second pipe is arranged inside the tank, the water that has passed through the second pipe has a higher temperature than the water that has passed through the first pipe. Further, the control device can adjust the ratio of the flow rate of water flowing through the first pipe to the flow rate of water flowing through the second pipe by controlling the water amount adjusting valve. That is, the control device can control the temperature of the water flowing into the heat transfer tube by controlling the flow rate of the low temperature water passing through the first pipe and the flow rate of the high temperature water passing through the second pipe. Here, the temperature of the water flowing inside the heat transfer tube predominantly acts on the surface temperature of the heat transfer tube rather than the temperature of the exhaust gas in contact with the surface of the heat transfer tube. Therefore, this exhaust heat recovery boiler can significantly change the surface temperature of the heat transfer tube. That is, the control device can control the surface temperature of the heat transfer tube to be significantly changed according to the measurement result of at least one of the corrosion rate, the temperature and the exhaust gas component, and is negative to the surface temperature of the heat transfer tube in the vicinity of the dew point. The corrosion rate of the heat transfer tube, which has a correlation with, can be adjusted. Therefore, according to this exhaust heat recovery boiler, corrosion of the heat transfer tube can be suppressed.

(Form 2)
The exhaust heat recovery boiler according to the second embodiment is the exhaust heat recovery boiler according to the first embodiment, in which the tank is a brackish water cylinder (brackish water separator) that separates water and steam.
The exhaust heat recovery boiler may include a brackish water cylinder used to separate steam and water. According to the exhaust heat recovery boiler according to the second embodiment, the brackish water cylinder is used as the tank according to the first embodiment. That is, this exhaust heat recovery boiler can realize the configuration of the exhaust heat recovery boiler according to the first embodiment without newly providing another tank.

(Form 3)
In the exhaust heat recovery boiler according to the third embodiment, at least a part of the second pipe is arranged in a portion where water is collected in the tank in the exhaust heat recovery boiler according to the first or second form.
According to the exhaust heat recovery boiler according to the third embodiment, at least a part of the second pipe is in direct contact with the hot water that has passed through the heat transfer pipe. Therefore, the water in the tank can directly heat the second pipe. That is, this exhaust heat recovery boiler can raise the temperature of the water flowing through the second pipe to a higher temperature than when the second pipe comes into contact with only the water vapor inside the tank. Then, this exhaust heat recovery boiler can supply water having a higher temperature to the heat transfer tube.

(Form 4)
The exhaust heat recovery boiler according to the fourth aspect is the exhaust heat recovery boiler according to any one of the first to third forms, in which the water temperature between the confluence portion of the water supply pipe and the water inlet of the heat transfer pipe is adjusted. A water temperature gauge to be measured is further provided, and the control device adjusts and controls the water amount adjusting valve according to the measurement result of the water temperature gauge.
According to the exhaust heat recovery boiler according to the fourth embodiment, the water temperature of the water supplied to the heat transfer tube is measured by a water temperature gauge. Therefore, the control device can adjust the temperature of the water supplied to the heat transfer tube to a specific temperature by adjusting the water amount adjusting valve according to the measurement result of the water temperature gauge. That is, in this exhaust heat recovery boiler, water having reached a specific temperature can be supplied to the heat transfer tube.

(Form 5)
The exhaust heat recovery boiler according to the fifth embodiment is the exhaust heat recovery boiler according to any one of the first to fourth forms, wherein the measuring device is a corrosion sensor including an electrode member that exposes an electrode surface inside the duct. The corrosion monitoring probe includes a probe temperature adjusting mechanism for adjusting the temperature of the electrode member, and the control device controls the probe temperature adjusting mechanism of the corrosion monitoring probe to monitor the corrosion. The probe is made to measure the corrosion rate at a plurality of different temperatures, and the temperature of the water supplied to the heat transfer tube is determined from the results of the measurement of the corrosion rate at the plurality of different temperatures so that the corrosion rate becomes lower than the allowable value. Then, the temperature of the water supplied to the heat transfer tube is adjusted and controlled to the determined temperature.
In the exhaust heat recovery boiler according to the fifth embodiment, since the corrosion monitoring probe has a probe temperature adjusting mechanism, the corrosion monitoring probe can measure the corrosion rate at different temperatures. As a result, the control device can acquire the relationship between the corrosion rate and the temperature in the duct, and can determine the temperature at which the corrosion rate becomes lower than the allowable value. Then, the control device can control the temperature of the water supplied to the heat transfer tube according to the determined temperature. That is, this exhaust heat recovery boiler can be controlled so that the corrosion rate is lower than the permissible value.

(Form 6)
The exhaust heat recovery boiler according to the sixth embodiment is the exhaust heat recovery boiler according to any one of the first to fifth forms, wherein the measuring device includes an electrode member exposed inside the duct and can measure the corrosion rate. The control device has a corrosion sensor, and when the corrosion rate measured by the corrosion sensor exceeds an allowable value, the ratio of the flow rate of water flowing through the second pipe to the flow rate of water flowing through the first pipe is set. Control to increase.
According to the exhaust heat recovery boiler according to the sixth embodiment, when the corrosion rate exceeds the permissible value, the temperature of the water supplied to the heat transfer tube is raised by controlling the flow rate ratio. Therefore, this exhaust heat recovery boiler can prevent the corrosion rate from exceeding the permissible value.

(Form 7)
The exhaust heat recovery boiler according to the seventh embodiment is the exhaust heat recovery boiler according to any one of the first to sixth aspects, wherein the measuring device has a thermometer for measuring the temperature in the vicinity of the heat transfer tube, and the control device. Controls to increase the ratio of the flow rate of water flowing through the second pipe to the flow rate of water flowing through the first pipe when the temperature near the heat transfer tube measured by the thermometer falls below a predetermined reference temperature. ..
It is known that there is a negative correlation between temperature and corrosion rate near the dew point. Therefore, if the temperature is known, the corrosion rate can be estimated. That is, if the surface temperature of the heat transfer tube is kept above a certain temperature, the corrosion rate can be kept below a certain value. The exhaust heat recovery boiler according to the seventh embodiment raises the temperature of the water supplied to the heat transfer tube according to the temperature measured by the thermometer. Therefore, this exhaust heat recovery boiler can keep the corrosion rate below a certain value.

(Form 8)
The exhaust heat recovery boiler according to the eighth embodiment is the exhaust heat recovery boiler according to the first to seventh forms, wherein the measuring device is an SOx analyzer for measuring the concentration of sulfur oxides which are exhaust gas components inside the duct, chloride. The control device includes at least one of an HCl analyzer for measuring hydrogen concentration and a moisture meter for measuring water concentration, and the control device determines the result of measurement of at least one of sulfur oxide concentration, hydrogen chloride concentration and water concentration. Correspondingly, the dew point temperature is predicted and the reference temperature is determined.
It is known that the corrosion rate changes depending on the sulfur oxide concentration, the hydrogen chloride concentration, and the water concentration in addition to the temperature. Therefore, the waste heat recovery boiler estimates the corrosion rate more accurately by considering at least one of the measured sulfur oxide concentration, hydrogen chloride concentration, and water concentration when estimating the corrosion rate. it can.

(Form 9)
The exhaust heat recovery boiler according to the ninth form is the exhaust heat recovery boiler according to any one of the first to eighth forms, wherein the water amount adjusting valve is attached to the first pipe and the flow rate of water flowing through the first pipe. It has a first valve that adjusts the amount of water, and a second valve that is attached to the second pipe and adjusts the flow rate of water flowing through the second pipe.
In the exhaust heat recovery boiler according to the ninth aspect, the flow rate of water flowing through the first pipe and the flow rate of water flowing through the second pipe can be adjusted separately by different valves. Therefore, this exhaust heat recovery boiler can easily control the flow rate of water flowing through the first pipe and the flow rate of water flowing through the second pipe.

(Form 10)
The method for controlling the temperature of the heat transfer pipe of the exhaust heat recovery boiler according to the tenth aspect is to have a duct having a flow path through which exhaust gas flows, a water inlet and a water outlet, and a heat transfer pipe arranged inside the duct. A water supply pipe connected to the water inlet of the heat transfer pipe, which forms between a diversion portion, a confluence portion located downstream of the diversion portion, and the confluence portion to the confluence portion. It has one pipe, a second pipe that branches at the first pipe and the diversion portion and merges with the first pipe again at the confluence portion, and water that has passed through the confluence portion of the heat transfer pipe. Using an exhaust heat recovery boiler including a water supply pipe for supplying to the water inlet and a tank connected to the water outlet and having at least a part of the second pipe arranged inside, the duct is provided. A measurement step of measuring at least one of the internal corrosion rate, temperature, and exhaust gas component, a temperature determination step of determining the temperature of water supplied to the heat transfer pipe according to the measurement result of the measurement step, and the above-mentioned A temperature adjustment step of adjusting the ratio of the flow rate of water flowing through the first pipe to the flow rate of water flowing through the second pipe and adjusting the surface temperature of the heat transfer tube to the temperature determined in the temperature determination step. Have.
The method for controlling the temperature of the heat transfer tube of the exhaust heat recovery boiler according to the tenth aspect is that the temperature flows into the heat transfer tube by adjusting the flow rate of low temperature water passing through the first pipe and the flow rate of high temperature water passing through the second pipe. The temperature of water is adjusted, and the surface temperature of the heat transfer pipe is adjusted. Therefore, the method of controlling the temperature of the heat transfer tube of the exhaust heat recovery boiler can significantly change the surface temperature of the heat transfer tube, as in the first embodiment. Therefore, this method of controlling the temperature of the heat transfer tube of the exhaust heat recovery boiler can suppress the corrosion of the heat transfer tube.

(Form 11)
The method for controlling the temperature of the heat transfer tube of the exhaust heat recovery boiler according to the eleventh embodiment is the method for controlling the temperature of the heat transfer tube of the exhaust heat recovery boiler according to the tenth aspect, wherein the measurement step is a plurality of different methods inside the duct. The heat transfer tube has a step of measuring the corrosion rate at a temperature, and the temperature determination step is performed on the heat transfer tube so that the corrosion rate becomes a value lower than an allowable value based on the results of the measurement of the corrosion rate at a plurality of different temperatures. It has a step of determining the temperature of the water to be supplied.
The method for controlling the temperature of the heat transfer tube of the exhaust heat recovery boiler according to the eleventh form can make the corrosion rate lower than the permissible value, as in the fifth form.

It is a structural drawing which shows the structure of the exhaust heat recovery boiler which concerns on 1st Embodiment of this invention. It is a detailed view which shows the detail of the part of the economizer of the exhaust heat recovery boiler shown in FIG. It is sectional drawing which shows the structure of the probe for corrosion monitoring of the exhaust heat recovery boiler shown in FIG. It is a top view which shows the main part of the corrosion monitoring probe shown in FIG. It is a flow chart which shows one procedure of the control process of the exhaust heat recovery boiler shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are designated by the same reference numerals and duplicate description will be omitted.

[First Embodiment]
<Composition>
FIG. 1 is a structural diagram showing a configuration of an exhaust heat recovery boiler according to the first embodiment of the present invention. Referring to FIG. 1, the exhaust heat recovery boiler 100 includes a duct 120, a superheater 140, an economizer 300, a brackish water cylinder 160, a high-pressure steam reservoir 180, and an evaporator (not shown). The exhaust heat recovery boiler 100 is a device that uses the heat of exhaust gas to generate steam. The exhaust heat recovery boiler 100 is, for example, a vertical type in which exhaust gas flows in the vertical direction, but may be a gas cross-flow type in which exhaust gas flows in the lateral direction. As an example, the steam generated in the exhaust heat recovery boiler 100 is supplied to a steam turbine (not shown) and used to drive a generator.

Hereinafter, each component of the exhaust heat recovery boiler 100 will be described separately.
As an example, the upstream side of the duct 120 communicates with an exhaust gas duct (not shown) of a combustion facility such as a garbage incinerator. The combustion equipment supplies high temperature exhaust gas toward the exhaust gas duct. Therefore, a flow path through which the exhaust gas flows is formed in the duct 120. Exhaust gas includes sulfur oxides, hydrogen chloride, water vapor, etc. generated by combustion of combustion equipment.
The economizer 300 is located on the downstream side of the flow path formed in the duct 120 with respect to the superheater 140 described later. Water is supplied to the economizer 300 from the water supply unit 900. Then, the economizer 300 uses the exhaust gas to preheat the supplied water, and supplies the preheated water to the brackish water cylinder 160.
The brackish water cylinder 160 is a container for containing water and steam, and has a function of separating water and steam. The steam separated by the brackish water cylinder 160 is supplied to the superheater 140 described later. On the other hand, the water separated by the brackish water cylinder 160 is supplied to an evaporator (not shown).
The evaporator is a heat exchanger that further heats the water supplied from the brackish water cylinder 160. The evaporator heats the supplied water to turn at least a part of the water into steam.
The superheater 140 is a heat exchanger that further superheats the supplied steam. The superheater 140 supplies the supplied steam as superheated steam to the high-pressure steam reservoir 180.
The high pressure steam reservoir 180 accommodates superheated steam. Further, the high-pressure steam reservoir 180 is connected to the steam turbine as an example, and supplies the stored superheated steam to the steam turbine.
As described above, since each component of the exhaust heat recovery boiler 100 has the above-mentioned configuration, the water supplied to the economizer 300 can be converted into superheated steam and supplied to the steam turbine.

Next, with reference to FIG. 2, the configuration of the portion of the economizer 300 of the exhaust heat recovery boiler 100 will be described in more detail. FIG. 2 is a detailed view showing the details of the portion of the economizer 300 of the exhaust heat recovery boiler 100. Referring to FIG. 2, the exhaust heat recovery boiler 100 further includes a water supply pipe 400, a water amount adjusting valve 500, a measuring device 600, a water temperature gauge 700, and a control device 800.
The economizer 300 includes a heat transfer tube 320. The heat transfer tube 320 has a water inlet 322 and a water outlet 324, and water flows from the water inlet 322 toward the water outlet 324. Further, the heat transfer tube 320 is arranged inside the duct 120. In other words, the heat transfer tube 320 is arranged at a position where the surface of the heat transfer tube 320 can come into contact with the exhaust gas flowing inside the duct 120. As a result, the heat transfer tube 320 has a function of exchanging heat between the water flowing inside the heat transfer tube 320 and the exhaust gas in contact with the surface of the heat transfer tube 320.

The water supply pipe 400 is connected to the water supply unit 900 and the water inlet 322 of the heat transfer pipe 320. The water supply pipe 400 has a diversion portion 462, a confluence portion 464 located on the downstream side of the diversion portion 462, a first pipe 420, and a second pipe 440. The first pipe 420 forms between the diversion portion 462 and the confluence portion 464. The second pipe 440 branches at the first pipe 420 and the diversion portion 462, and joins the first pipe 420 again at the confluence portion 464. Further, the water supply pipe 400 supplies the water that has passed through the confluence portion 464 to the water inlet 322 of the heat transfer pipe 320. Therefore, in the water supply pipe 400, the water supplied from the water supply unit 900 is divided into the water flowing through the first pipe 420 and the water flowing through the second pipe 440 at the diversion unit 462, and the first pipe at the confluence unit 464. The water flowing through the 420 and the water flowing through the second pipe 440 can be merged. In other words, the water supply pipe 400 can supply the water that has passed through the first pipe 420 or the second pipe 440 to the water inlet 322.

The water amount adjusting valve 500 has a first valve 520 and a second valve 540 as an example. The first valve 520 is attached to the first pipe 420. As a result, the first valve 520 can adjust the flow rate of water flowing through the first pipe 420. On the other hand, the second valve 540 is attached to the second pipe 440. As a result, the second valve 540 can adjust the flow rate of water flowing through the second pipe 440. That is, the water amount adjusting valve 500 can adjust the ratio of the flow rate of water flowing through the first pipe 420 and the flow rate of water flowing through the second pipe 440.

The brackish water cylinder 160 is in fluid communication with the water outlet 324 of the heat transfer tube 320. As a result, the heated water flows into the brackish water cylinder 160 through the heat transfer tube 320. In other words, the water contained in the brackish water cylinder 160 is hotter than the water supplied by the water supply unit 900. Further, in the brackish water cylinder 160, at least a part of the second pipe 440 is arranged inside. Therefore, the water passing through the second pipe 440 is heated by the water or steam inside the brackish water cylinder 160. Then, the water that has passed through the second pipe 440 has a higher temperature than the water that has passed through the first pipe 420. Therefore, when the ratio of the flow rate of water flowing through the first pipe 420 to the flow rate of water flowing through the second pipe 440 is adjusted, the temperature of the water supplied to the heat transfer tube 320 changes. Further, in the present embodiment, at least a part of the second pipe 440 is arranged in a portion of the brackish water cylinder 160 where water is collected. That is, the second pipe 440 comes into contact with the water accumulated in the brackish water cylinder 160.

The measuring device 600 measures at least one of the corrosion rate, the temperature and the exhaust gas component inside the duct 120. More specifically, the measuring device 600 includes a corrosion monitoring probe 620 (hereinafter, referred to as a probe 620) as an example. Since the probe 620 has a probe temperature adjusting mechanism 624 described later, the corrosion rate inside the duct 120 can be measured at a set temperature.

Here, an example of the probe 620 will be described in more detail. FIG. 3 is a cross-sectional view showing the configuration of the probe 620 of the exhaust heat recovery boiler 100. Further, FIG. 4 is a plan view showing a main part of the probe 620. With reference to FIGS. 3 and 4, the probe 620 is a corrosion sensor provided with a pair of electrode members 622a, 622b for measuring the corrosion rate, and a probe temperature adjusting mechanism 624.
, Electrode 626 for temperature measurement such as thermocouple, holder 628, cover 630, lead wire 636, lead wire 637, connecting tube 638, impedance measuring device 640 and temperature measuring instrument 650. Further, the probe temperature adjusting mechanism 624 includes a temperature adjusting gas source 648, a temperature adjusting valve 642, a gas supply pipe 644, a flow meter 645, and a probe electrode temperature control device 646.

In the present embodiment, the electrode members 622a and 622b are composed of two conductors of the same material. More specifically, the electrode members 622a and 622b are made of the same material as the heat transfer tube 320 from the viewpoint of detecting the corrosion rate of the heat transfer tube 320, for example. Further, the electrode members 622a and 622b are rectangular parallelepipeds having a substantially square planar shape, and are adjacent to each other with a gap between them (see FIG. 4). As a result, a liquid junction forming portion 634 for forming a liquid junction of the condensed water is formed in the portion between the electrode members 622a and 622b. Further, the electrode members 622a and 622a are embedded in the holder 628. One surface (hereinafter referred to as a front side surface) of the electrode members 622a and 622b is exposed inside the duct 120, and the other surface (hereinafter referred to as a back surface surface) is connected to the lead wire 636, respectively. There is. Then, the lead wire 636 passes through the inside of the connecting pipe 638 and is connected to the impedance measuring device 640. As a result, the impedance measuring device 640 can measure the impedance between the electrode members 622a and 622b by applying an AC voltage to the electrode members 622a and 622b. Further, the impedance measuring device 640 is connected to the control device 800. As a result, the control device 800 can acquire the measured impedance. Then, the control device 800 can determine the reaction resistance and the solution resistance separately by frequency-analyzing the measured impedance. Further, the control device 800 can calculate the corrosion rate from the reaction resistance and the solution resistance by using a known method. That is, the control device 800 can acquire data on the corrosion rate.

The electrode 626 for temperature measurement is embedded in the holder 628 like the electrode members 622a and 622b. One surface of the electrode 626 is exposed inside the duct 120 and the other surface is connected to the lead wire 637. The lead wire 637 passes through the inside of the connecting pipe 638 and is connected to the temperature measuring instrument 650. As a result, the temperature measuring instrument 650 can measure the temperature of the portion of the electrode 626, that is, the temperature in the vicinity of the electrode members 622a and 622b for measuring the corrosion rate. Further, the temperature measuring instrument 650 is connected to the control device 800. As a result, the control device 800 can acquire temperature data in the vicinity of the electrode members 622a and 622b.

The cover 630 is in close contact with the holder 628 to form a heat medium space 632. As a result, the surface of the electrode members 622a and 622b connected to the lead wire 636 and the surface of the electrode 626 connected to the lead wire 637 are exposed to the heat medium space 632, respectively. Further, the cover 630 is provided with a connecting pipe 638 for circulating a heat medium such as air or water in the heat medium space 632. A gas supply pipe 644 is inserted through the connecting pipe 638. The gas supply pipe 644 connects a temperature control gas source 648 such as a compressor or a gas cylinder to a heat medium space 632. Further, a temperature control valve 642 and a flow meter 645 are provided between the temperature control gas source 648 and the heat medium space 632. Therefore, by adjusting the temperature adjusting valve 642, the temperature adjusting gas supplied from the temperature adjusting gas source 648 is supplied to the heat medium space 632. That is, the temperature of the heat medium space 632 approaches the temperature of the supplied temperature adjusting gas. As a result, the probe electrode temperature control device 646 can adjust the electrode members 622a and 622b for measuring the corrosion rate and the electrode 626 for temperature measurement to the set temperature. That is, the probe 620 can measure the corrosion rate at the set temperature by adjusting the temperatures of the electrode members 622a and 622b for measuring the corrosion rate by using the probe temperature adjusting mechanism 624.
The above is the description of the probe 620 included in the measuring device 600. The probe 620 does not have to have the above configuration as long as it has a function of measuring the corrosion rate inside the duct 120 at a set temperature.

See FIG. 2 again. In the exhaust heat recovery boiler 100, the probe 620 is arranged in the vicinity of the heat transfer tube 320 as an example. As a result, the probe 620 can measure the corrosion rate close to the corrosion rate of the heat transfer tube 320. Here, the vicinity of the heat transfer tube 320 is a position where, when the same material as the heat transfer tube 320 is arranged at the position in the vicinity, the heat transfer tube 320 and the material arranged at the position in the vicinity have the same corrosion rate. Call it.

As an example, the water temperature gauge 700 is arranged between the confluence portion 464 of the water supply pipe 400 and the water inlet 322 of the heat transfer pipe 320. As a result, the water temperature gauge 700 has a function of measuring the water temperature between the confluence portion 464 of the water supply pipe 400 and the water inlet 322 of the heat transfer pipe 320. That is, the water temperature gauge 700 can measure the water temperature supplied to the heat transfer tube 320.
The control device 800 can make the probe 620 measure the corrosion rate at a plurality of different temperatures by controlling the probe temperature adjusting mechanism 624 of the probe 620. Further, the control device 800 can determine the temperature of the water supplied to the heat transfer tube 320 such that the corrosion rate becomes lower than the permissible value from the measurement results of the corrosion rate at a plurality of different temperatures of the probe 620. The permissible value is a value that can be arbitrarily determined. More specifically, the permissible value can be determined according to the equipment life, operating conditions, and the like. Further, the control device 800 adjusts and controls the temperature of the water supplied to the heat transfer tube 320 to the determined temperature by adjusting the water amount adjusting valve 500 according to the measurement result of the water temperature gauge 700.

<Method of controlling the temperature of the heat transfer tube of the exhaust heat recovery boiler>
Next, a method of controlling the temperature of the heat transfer tube 320 of the exhaust heat recovery boiler 100 of the present embodiment will be described. In explaining the method of controlling the temperature of the heat transfer tube 320 of the exhaust heat recovery boiler 100, the initial state of each component constituting the exhaust heat recovery boiler 100 will be described.
In the initial state, the inside of the duct 120 contains exhaust gas. Further, the water supply unit 900 supplies water to the water supply pipe 400. Therefore, the supplied water is supplied to the heat transfer tube 320 via the water supply pipe 400. Then, the water supplied to the heat transfer tube 320 is heated by the heat transfer tube 320 and supplied to the brackish water cylinder 160.

On the premise of the above, a method of controlling the temperature of the heat transfer tube 320 of the exhaust heat recovery boiler 100 will be described with reference to the drawings. FIG. 5 is a flow chart showing one procedure of a method for controlling the temperature of the heat transfer tube 320 of the exhaust heat recovery boiler 100.

Referring to FIG. 5, in step S100, the control device 800 confirms the water supply temperature to the heat transfer tube 320 by using the water temperature gauge 700. Then, the control device 800 acquires the information on the water supply temperature. In step S200, by controlling the probe temperature adjusting mechanism 624, the temperature of the probe 620 is changed to a predetermined temperature and controlled to be held for a certain period of time.
Next, in step S300, the control device 800 acquires the temperature of the probe 620 from the output of the probe 620. Then, the control device 800 confirms that the probe 620 has reached a predetermined temperature.
Next, in step S400, the control device 800 measures the corrosion rate corresponding to this temperature for a certain period of time from the output of the probe 620, and acquires information on the corrosion rate.
Next, in step S500, the control device 800 determines whether the corrosion rate at a predetermined temperature obtained from the output of the probe 620 is equal to or higher than the allowable value. If the corrosion rate at a predetermined temperature is not greater than or equal to the permissible value, the control device 800 returns the process to step S200. Then, in step S200 again, the control device 800 sets the temperature at which the corrosion rate has not been measured and is lower than the temperature of the probe 620 set in the previous step S200 to a new predetermined temperature. .. After that, the control device 800 controls the probe temperature adjusting mechanism 624 to lower the temperature of the probe 620 to a newly set predetermined temperature. As a result, in the next repetition, the control device 800 can acquire information on the corrosion rate at a temperature not measured.
On the other hand, if the corrosion rate is equal to or higher than the permissible value in step S500, the control device 800 proceeds to step S600. In this way, the control device 800 repeats the process from step S200 to step S400 until the corrosion rate becomes equal to or higher than the allowable value, so that the control device 800 can acquire information on the corrosion rate at a plurality of different temperatures.

Next, in step S600, the control device 800 grasps the relationship between the temperature and the corrosion rate from the temperature and corrosion rate information obtained from the output of the probe 620. It is known that there is a negative correlation between the temperature near the dew point of sulfuric acid and the corrosion rate.
Next, in step S700, the control device 800 determines an allowable temperature at which the corrosion rate can be below the allowable value. More specifically, first, the control device 800 compares the corrosion rate corresponding to the highest temperature among the plurality of measured temperatures with the permissible value. Next, the control device 800 compares the corrosion rate corresponding to the second highest temperature among the plurality of measured temperatures with the permissible value. Then, the control device 800 compares the corrosion rate corresponding to the third highest temperature among the measured plurality of temperatures with the permissible value. In this way, the control device 800 compares the allowable value in order from the corrosion rate corresponding to the higher temperature among the plurality of measured temperatures. Then, the control device 800 finds the temperature at which the corrosion rate first exceeds the permissible value among the measured temperatures, and sets the temperature next to the found temperature as the permissible temperature. After that, the control device 800 determines this permissible temperature as the water supply temperature. In addition, in order to further reduce the corrosion rate, the control device 800 may determine a temperature higher than the permissible temperature by a certain temperature as the water supply temperature.

Next, in step S800, the control device 800 determines whether the currently supplied water supply temperature, that is, the water supply temperature confirmed in step S100 exceeds the allowable temperature. More specifically, the control device 800 compares the water supply temperature confirmed in step S100 with the water supply temperature determined in step S700.
When the water supply temperature confirmed in step S100 is lower than the temperature determined in step S700, the control device 800 determines the water supply temperature currently being supplied in step S700, and the control device 800 determines the water supply temperature determined in step S700. The water supply temperature is raised so as to be. The control device 800 raises the water supply temperature by controlling the water amount adjusting valve 500. As a result, the exhaust heat recovery boiler 100 is controlled to keep the corrosion rate below the permissible value.
On the other hand, when the water supply temperature confirmed in step S100 is higher than the water supply temperature determined in step S700, the control device 800 determines the water supply temperature currently being supplied in step S800, and the control device 800 determines the water supply temperature currently being supplied in step S500. Lower the water supply temperature to the required temperature. The control device 800 lowers the water supply temperature by controlling the water amount adjusting valve 500.
Next, in S900, the water temperature gauge 700 is used to confirm the water supply temperature to the heat transfer tube 320. Then, the control device 800 acquires the information on the water supply temperature, and confirms whether the water supply temperature is the water supply temperature determined in step S700.
When the control device 800 finishes the process of step S900, the control device 800 repeats the process from step S100 again after a certain period of time has elapsed in S1000. As a result, the exhaust heat recovery boiler 100 efficiently recovers heat energy by preventing the surface of the heat transfer tube 320 from becoming too hot and reducing the amount of heat recovery, and preventing the surface of the heat transfer tube 320 from becoming too low and corroding. It is possible to control.

<Action / effect>
Next, the action / effect of the exhaust heat recovery boiler 100 of the present embodiment will be described below.
(First effect)
The exhaust heat recovery boiler 100 according to the present embodiment includes a control device 800 that controls the temperature of water supplied to the heat transfer tube 320 according to the corrosion rate measured by the probe 620. Therefore, the exhaust heat recovery boiler 100 can significantly change the surface temperature of the heat transfer tube 320 by adjusting the temperature of the water supplied to the heat transfer tube 320. Further, in changing the surface temperature of the heat transfer tube 320, the exhaust heat recovery boiler 100 does not need to raise the temperature of the exhaust gas in contact with the heat transfer tube 320 or increase the flow rate of the exhaust gas flowing through the duct 120. Therefore, the exhaust heat recovery boiler 100 can keep the corrosion rate of the heat transfer tube 320 below the permissible value, and can suppress the corrosion of the heat transfer tube 320.

(Second effect)
Further, the exhaust gas used for heat recovery is discharged from the duct 120 after the heat is recovered by the heat transfer tube 320. If the surface of the heat transfer tube 320 becomes too high, the temperature of the exhaust gas and the temperature of the surface of the heat transfer tube 320 become close to each other, so that the amount of heat recovered from the exhaust gas at the position of the heat transfer tube 320 decreases. Therefore, the exhaust heat recovery boiler 100 discards the high-temperature exhaust gas. Discarding the high-temperature exhaust gas is equivalent to not recovering the heat energy that can be recovered by the exhaust heat recovery boiler 100. However, since the exhaust heat recovery boiler 100 controls the temperature of the water supplied to the heat transfer tube 320 according to the corrosion rate, the temperature of the gas discharged from the duct 120 does not become too high. That is, the exhaust heat recovery boiler 100 can effectively recover the heat energy of the exhaust gas in a limited heat transfer area without discarding it more than necessary.

(Third effect)
A part of the second pipe 440 of the water supply pipe 400 is arranged inside the brackish water cylinder 160. As a result, the water passing through the second pipe 440 is heated by the high-temperature water and steam inside the brackish water cylinder 160. That is, the exhaust heat recovery boiler 100 can raise the temperature of the water supplied to the heat transfer tube 320 without providing another heating means for heating the water supplied to the heat transfer tube 320.

(Fourth effect)
Further, a part of the second pipe 440 is in contact with the hot water inside the brackish water cylinder 160. Therefore, the water passing through the second pipe 440 is heated faster than when the water accumulated in the brackish water cylinder 160 and the second pipe 440 do not come into contact with each other (when the second pipe 440 is heated by the steam inside the brackish water cylinder 160). To. That is, if the flow rate of water passing through the second pipe 440 is the same, the configuration in which the second pipe 440 comes into contact with the water accumulated in the brackish water cylinder 160 is the configuration in which the second pipe 440 does not come into contact with the water accumulated in the brackish water cylinder 160. The temperature of the water that has passed through the second pipe 440 is higher than that of the second pipe 440. Therefore, the exhaust heat recovery boiler 100 can heat the water that has passed through the second pipe 440 to a higher temperature.

(Fifth effect)
Further, the exhaust heat recovery boiler 100 includes a water temperature gauge 700 capable of measuring the water temperature supplied to the heat transfer tube 320. Then, the control device 800 controls the temperature of the water supplied to the heat transfer tube 320 according to the measurement result of the water temperature gauge 700. As a result, the exhaust heat recovery boiler 100 can supply water having a specific temperature to the heat transfer tube 320, and the temperature of the heat transfer tube 320 can be easily adjusted.

<Modification example>
Next, a modified example of the exhaust heat recovery boiler 100 of the present embodiment will be described below.
(First modification)
Further, the exhaust heat recovery boiler 100 may include, in addition to the brackish water cylinder 160, a tank in which fluid is communicated with the water outlet 324 of the heat transfer tube 320. In this case, at least a part of the second pipe 440 is arranged inside the tank. This is because even in such a case, the water or steam inside the tank can heat the water flowing through the second pipe 440. Further, by using a tank in which fluid is communicated with the water outlet 324, the exhaust heat recovery boiler 100 has a heat transfer tube 320.
The water heated by the above water and the steam obtained by further heating the water can be used as a heat source for heating the second pipe 440. That is, the exhaust heat recovery boiler 100 can heat the water supplied to the heat transfer tube 320 without providing another heating means such as a heater. Here, the tank refers to a facility that accommodates at least one of water and steam, and the brackish water cylinder 160 is an example of a tank. The high-pressure steam reservoir 180 is also an example of a tank.

(Second modification)
Further, in the present embodiment, the probe 620 is arranged in the vicinity of the heat transfer tube 320. However, the probe 620 may be located anywhere inside the duct 120 as long as it can measure the data required to estimate the corrosion rate of the heat transfer tube 320. For example, if the exhaust gas flow is biased and the temperature distribution inside the duct is considered to be uneven, the probe should be located at a location that is most suitable for estimating the corrosion rate of the heat transfer tube 320 after grasping the temperature distribution inside the duct in advance. Should be placed. This is because if the corrosion rate of the heat transfer tube 320 can be estimated using the data measured by the probe 620, the temperature of the water supplied to the heat transfer tube 320 can be determined accordingly.

(Third variant)
Further, the measuring device 600 may have a corrosion sensor that measures the corrosion rate in the vicinity of the heat transfer tube 320. In this case, the control device 800 controls to increase the ratio of the flow rate of water flowing through the second pipe 440 to the flow rate of water flowing through the first pipe 420 when the corrosion rate measured by the corrosion sensor exceeds the permissible value. .. As a result, even if the exhaust heat recovery boiler 100 is not provided with the probe 620, the corrosion sensor is installed in the limited space inside the duct 120 to prevent the corrosion rate of the heat transfer tube 320 from exceeding the allowable value. This is because the heat transfer tube 320 can be prevented from being excessively corroded.

(Fourth modification)
In the present embodiment, the corrosion sensor includes a pair of electrode members 622a and 622b, and the impedance between the electrode members 622a and 622b is measured and analyzed to obtain the corrosion rate data. However, the measurement method and the structure of the sensor are based on this. Not as long. The short-circuit current when the dissimilar electrodes are short-circuited by the condensed phase may be measured, or the resonance frequency of the crystal oscillator on the electrode surface may be measured. Corrosion rate data can be obtained by analyzing the output of any sensor. Further, by using an electrode member made of the same material as the heat transfer tube 320 for the corrosion sensor, it is possible to estimate the corrosion rate of the heat transfer tube 320 from the output of the corrosion sensor. By changing the electrode material to a material that is more corrosive than the material of the heat transfer tube 320, it becomes possible to grasp the corrosion tendency of the heat transfer tube 320 in advance.

(Fifth variant)
Further, the measuring device 600 may have a thermometer that measures the temperature in the vicinity of the heat transfer tube 320. In this case, the control device 800 controls to increase the ratio of the flow rate of water flowing through the second pipe 440 to the flow rate of water flowing through the first pipe 420 when the temperature measured by the thermometer falls below a predetermined reference temperature. do. As described above, it is known that there is a negative correlation between the temperature near the dew point of sulfuric acid and the corrosion rate. Therefore, the corrosion rate can be estimated by measuring the temperature of the portion of the heat transfer tube 320. Therefore, even if the exhaust heat recovery boiler 100 does not include the probe 620, it suppresses corrosion of the heat transfer tube 320 by controlling the temperature of the water supplied to the heat transfer tube 320 according to the temperature measured by the thermometer. be able to. The reference temperature may be arbitrarily determined in consideration of the relationship between the temperature and the corrosion rate.

(Sixth variant)
In addition to the thermometer of the modified example 4, the measuring device 600 includes an SOx analyzer for measuring the sulfur oxide concentration, an HCl analyzer for measuring the hydrogen chloride concentration, and a moisture meter for measuring the water concentration in the vicinity of the heat transfer tube 320. At least one of them may be provided. In this case, the control device 800 determines a reference temperature to be compared with the temperature measured by the thermometer according to the result of at least one of the measured sulfur oxide concentration, hydrogen chloride concentration and water concentration. .. Then, the control device 800 controls to increase the ratio of the flow rate of water flowing through the second pipe 440 to the flow rate of water flowing through the first pipe 420 when the temperature measured by the thermometer falls below this reference temperature. ..
As described above, it is known that the corrosion rate changes depending on the sulfur oxide concentration, the hydrogen chloride concentration and the water concentration in addition to the temperature. In this way, a more accurate corrosion rate can be estimated by considering at least one of the measured sulfur oxide concentration, hydrogen chloride concentration, and water concentration. Then, the exhaust heat recovery boiler 100 can suppress the corrosion of the heat transfer tube 320 in consideration of a more accurate corrosion rate.

ここで、

である。
大塚の式を用いることで、硫黄酸化物濃度及び水分濃度から硫酸露点が計算できることが知られている。これにより、排熱回収ボイラ１００は、伝熱管３２０の近傍の温度が硫酸露点を下回ることを防止することができ、伝熱管３２０の腐食を抑止することができる。なお、伝熱管３２０の腐食をさらに抑止するために、制御装置８００は、硫酸露点の温度よりも高い温度を基準温度としてもよい。また、大塚の式は、一例であり、制御装置８００は、他の式を用いて、排ガス成分から、露点温度を予測してもよい。なお、排ガス成分には、硫黄酸化物、塩化水素、水分等が含まれる。 (7th variant)
Further, in the modification 6, the control device 800 may predict the sulfuric acid dew point from the sulfur oxide concentration and the water concentration by using Otsuka's formula, and may use the sulfuric acid dew point as the reference temperature. Otsuka's formula is expressed by formula (1).

here,

Is.
It is known that the sulfuric acid dew point can be calculated from the sulfur oxide concentration and the water concentration by using Otsuka's formula. As a result, the exhaust heat recovery boiler 100 can prevent the temperature in the vicinity of the heat transfer tube 320 from falling below the dew point of sulfuric acid, and can suppress the corrosion of the heat transfer tube 320. In addition, in order to further suppress the corrosion of the heat transfer tube 320, the control device 800 may set a temperature higher than the temperature of the sulfuric acid dew point as a reference temperature. Further, Otsuka's formula is an example, and the control device 800 may predict the dew point temperature from the exhaust gas component by using another formula. The exhaust gas component includes sulfur oxides, hydrogen chloride, water and the like.

(8th variant)
When the measuring device 600 includes at least one of an SOx analyzer for measuring the sulfur oxide concentration, an HCl analyzer for measuring the hydrogen chloride concentration, and a moisture meter for measuring the water concentration in the vicinity of the heat transfer tube 320, It is not necessary to provide the thermometer of the modified example 4. In this case, the control device 800 measures the flow rate of water flowing through the first pipe 420 when the measurement result of at least one of the sulfur oxide concentration, the hydrogen chloride concentration and the water concentration exceeds or falls below a predetermined value. Control is performed to increase the ratio of the flow rate of water flowing through the second pipe 440 to.
As described above, it is known that the dew point temperature can be predicted from the exhaust gas component. Therefore, when the temperature inside the duct 120 is predictable, such as being substantially constant, the dew point temperature predicted from the exhaust gas component can be compared with the predicted temperature inside the duct 120. As a result, the exhaust heat recovery boiler 100 can prevent the predicted temperature inside the duct 120 from falling below the predicted dew point temperature, and can suppress corrosion of the heat transfer tube 320. That is, if the measuring device 600 can measure the exhaust gas component, the exhaust heat recovery boiler 100 can suppress the corrosion of the heat transfer tube 320. A predetermined value to be compared with the measurement result of the measuring device 600 may be arbitrarily determined.

(9th variant)
Further, in the case of the modification 8, the control device 800 with respect to the flow rate of water flowing through the first pipe 420 so that the temperature of the water supplied to the heat transfer tube 320 is higher than the dew point temperature predicted from the exhaust gas component. Control may be performed to increase the ratio of the flow rate of water flowing through the second pipe 440.
As a result, the exhaust heat recovery boiler 100 can set the temperature of the water flowing inside the heat transfer tube 320 to be higher than the dew point temperature. Further, the temperature of the exhaust gas in contact with the heat transfer tube 320 is higher than the temperature of the water flowing inside the heat transfer tube 320 because heat is recovered from the exhaust gas by the water flowing inside the heat transfer tube 320. That is, both the temperature of the water flowing inside the heat transfer tube 320 and the temperature of the exhaust gas in contact with the heat transfer tube 320 are higher than the dew point temperature, and the surface temperature of the heat transfer tube 320 is naturally higher than the dew point temperature. Become. Therefore, the exhaust heat recovery boiler 100 can suppress the corrosion of the heat transfer tube 320.

(10th variant)
In the present embodiment, the water amount adjusting valve 500 has a first valve 520 and a second valve 540. However, the water volume adjusting valve 500 does not have to have either the first valve 520 or the second valve 540. This is because even if the water amount adjusting valve 500 includes only one of the first valve 520 and the second valve 540, it is possible to adjust the ratio of the flow rate of water flowing through the first pipe 420 and the second pipe 440. This is because the exhaust heat recovery boiler 100 can adjust the temperature of the water supplied to the heat transfer tube 320 if the ratio of this flow rate can be adjusted. Further, the water amount adjusting valve 500 may include a three-way valve that allows water to flow through either the first pipe 420 or the second pipe 440. Similarly, the three-way valve can adjust the ratio of the flow rates of water flowing through the first pipe 420 and the second pipe 440. The water amount adjusting valve 500 may have any configuration as long as the water amount adjusting valve 500 can adjust the ratio of the flow rate of water flowing through the first pipe 420 to the flow rate of water flowing through the second pipe 440.

100: Exhaust heat recovery boiler 120: Duct 140: Superheater 160: Steam water cylinder 300: Economizer 320: Heat transfer pipe 322: Water inlet 324: Water outlet 400: Water supply pipe 420: First pipe 440: Second pipe 462: Divergence Part 464: Confluence part 500: Water amount adjustment valve 520: First valve 540: Second valve 600: Measuring device 620: Probe 624: Probe temperature adjustment mechanism 700: Water temperature gauge 800: Control device 900: Water supply part

Claims (11)

A duct with a flow path through which exhaust gas flows and
A heat transfer tube having a water inlet and a water outlet and arranged inside the duct,
A first water supply pipe connected to the water inlet of the heat transfer pipe, which forms between a diversion portion, a confluence portion located downstream of the diversion portion, and the confluence portion to the confluence portion. The heat transfer pipe has a pipe and a second pipe that branches at the first pipe and the diversion portion and merges with the first pipe again at the confluence portion, and water that has passed through the confluence portion is taken into the heat transfer pipe. Water supply piping to supply to the water inlet,
A tank in which fluid is communicated with the water outlet of the heat transfer pipe and at least a part of the second pipe is arranged inside.
A water amount adjusting valve that adjusts the ratio of the flow rate of water flowing through the first pipe to the flow rate of water flowing through the second pipe.
A measuring device that measures at least one of the corrosion rate, temperature, and exhaust gas component inside the duct.
A control device that adjusts and controls the water amount adjustment valve according to the measurement result of the measuring device, and
To prepare
Exhaust heat recovery boiler. In the exhaust heat recovery boiler according to claim 1,
The tank is a brackish water cylinder that separates water and steam.
Exhaust heat recovery boiler. In the exhaust heat recovery boiler according to claim 1 or 2.
At least a part of the second pipe is arranged in a portion of the tank where water collects.
Exhaust heat recovery boiler. In the exhaust heat recovery boiler according to any one of claims 1 to 3,
A water temperature gauge for measuring the water temperature between the confluence portion of the water supply pipe and the water inlet of the heat transfer pipe is further provided.
The control device adjusts and controls the water amount adjusting valve according to the measurement result of the water temperature gauge.
Exhaust heat recovery boiler. In the exhaust heat recovery boiler according to any one of claims 1 to 4.
The measuring device includes a corrosion monitoring probe having a corrosion sensor including an electrode member that exposes an electrode surface inside the duct, and a probe temperature adjusting mechanism for adjusting the temperature of the electrode member.
By controlling the probe temperature adjusting mechanism of the corrosion monitoring probe, the control device causes the corrosion monitoring probe to measure the corrosion rate at a plurality of different temperatures, and measures the corrosion rate at the plurality of different temperatures. From the result, the temperature of the water supplied to the heat transfer tube is determined so that the corrosion rate becomes lower than the allowable value, and the temperature of the water supplied to the heat transfer tube is adjusted and controlled to the determined temperature.
Exhaust heat recovery boiler. In the exhaust heat recovery boiler according to any one of claims 1 to 5,
The measuring device includes an electrode member exposed inside the duct and has a corrosion sensor capable of measuring a corrosion rate.
When the corrosion rate measured by the corrosion sensor exceeds the permissible value, the control device is the first.
Control to increase the ratio of the flow rate of water flowing through the second pipe to the flow rate of water flowing through the pipe.
Exhaust heat recovery boiler. In the exhaust heat recovery boiler according to any one of claims 1 to 6,
The measuring device has a thermometer that measures the temperature in the vicinity of the heat transfer tube.
The control device increases the ratio of the flow rate of water flowing through the second pipe to the flow rate of water flowing through the first pipe when the temperature near the heat transfer tube measured by the thermometer falls below a predetermined reference temperature. To control,
Exhaust heat recovery boiler. In the exhaust heat recovery boiler according to any one of claims 1 to 7.
The measuring device includes at least one of an SOx analyzer that measures the concentration of sulfur oxides, which is an exhaust gas component, an HCl analyzer that measures the concentration of hydrogen chloride, and a moisture meter that measures the water concentration inside the duct. Prepare,
The control device predicts the dew point temperature and determines the reference temperature according to the result of measurement of at least one of the sulfur oxide concentration, the hydrogen chloride concentration and the water concentration.
Exhaust heat recovery boiler. In the exhaust heat recovery boiler according to any one of claims 1 to 8.
The water amount adjusting valve is a first valve attached to the first pipe and adjusting the flow rate of water flowing through the first pipe, and a first valve attached to the second pipe and adjusting the flow rate of water flowing through the second pipe. Has 2 valves,
Exhaust heat recovery boiler. A duct with a flow path through which exhaust gas flows and
A heat transfer tube having a water inlet and a water outlet and arranged inside the duct,
A first water supply pipe connected to the water inlet of the heat transfer pipe, which forms between a diversion portion, a confluence portion located downstream of the diversion portion, and the confluence portion to the confluence portion. The heat transfer pipe has a pipe and a second pipe that branches at the first pipe and the diversion portion and merges with the first pipe again at the confluence portion, and water that has passed through the confluence portion is taken into the heat transfer pipe. Water supply piping to supply to the water inlet,
A tank connected to the water outlet and having at least a part of the second pipe arranged inside.
Using a heat recovery steam generator equipped with
A measurement process that measures at least one of the corrosion rate, temperature, and exhaust gas components inside the duct.
A temperature determination step of determining the temperature of water supplied to the heat transfer tube according to the measurement result of the measurement step, and
A temperature adjustment step of adjusting the ratio of the flow rate of water flowing through the first pipe to the flow rate of water flowing through the second pipe and adjusting the surface temperature of the heat transfer tube to the temperature determined in the temperature determination step.
Have,
How to control the temperature of the heat transfer tube of the exhaust heat recovery boiler. In the method for controlling the temperature of the heat transfer tube of the exhaust heat recovery boiler according to claim 10.
The measurement step includes a step of measuring the corrosion rate at a plurality of different temperatures inside the duct.
The temperature determination step includes a step of determining the temperature of water supplied to the heat transfer tube so that the corrosion rate becomes a value lower than the permissible value from the results of measuring the corrosion rate at the plurality of different temperatures.
How to control the temperature of the heat transfer tube of the exhaust heat recovery boiler.

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