JP2004198006A - Iron ion crystallization restricting system and superheated steam plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the generation of malfunction due to the iron particles by preventing the generation of large iron particles having a particle diameter exceeding 30 μm in a circulating water supply passage. <P>SOLUTION: A chemicals throw-in means for throwing a PH adjusting chemical (for example, ammonia) is provided to adjust PH inside the circulating water supply passage 22. The chemicals throw-in means 26 is provided with a control means 26d for controlling a throw-in quantity of the chemical, and controls the throw-in quantity of the chemical so that PH inside the circulating water supply passage 22 becomes 9.30-9.45. This iron ion crystallization restricting system can restrict hydraulic accelerating corrosion, and since PH of the circulating water supply passage 22 is adjusted in a critical range wherein crystallization of the iron ion and growth of the crystallized iron particle can be restricted, crystallization of iron ions and growth of the crystallized iron particles can be restricted. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an iron ion crystallization suppression system that suppresses the growth of crystallization particles of iron ions in an exhaust heat recovery plant or the like that heats water using exhaust heat, specifically, The present invention can be applied to a waste heat recovery plant in a combined power generation plant combining a turbine, a waste heat recovery plant using waste heat of a gas turbine, and a steam turbine. Further, the present invention provides a superheated steam plant that generates a superheated steam including a steam boiler and a superheater that superheats the steam supplied from the steam boiler, and has a disadvantage that iron crystallized particles diffuse into a steam system. It is intended to provide a superheated steam plant in which the above is prevented.
[0002]
[Prior art]
Exhaust heat recovery plants are installed in gas turbines and garbage incineration facilities, and are equipped with economizers, steam boilers and superheaters, which use exhaust heat to heat water and generate hot water and superheated steam. Has been generated.
[0003]
The exhaust gas immediately after being exhausted from the gas turbine has a very high temperature. For this reason, the exhaust heat recovery plant sequentially installs the devices in the exhaust stack of the gas turbine so that the heat of the exhaust gas of the gas turbine can be used in stages from a high temperature stage to a low temperature stage. Such an exhaust heat recovery plant is described in Patent Document 1 below. The steam and hot water generated by the waste heat recovery plant are used, for example, to power steam turbines or to be used as heat sources for facilities such as hot water pools and building air conditioning via heat exchangers. It is returned to the water in the vessel and is again introduced into the water supply path. Some generate superheated steam.
[0004]
Some exhaust heat recovery plants are provided with a circulating water supply path for circulating feedwater and a low-pressure economizer in a low-temperature region of the exhaust pipe of a gas turbine in order to preheat the feedwater using exhaust heat. The circulation water supply path of the low-pressure economizer is provided with a circulation pump for circulating the water supply, and the water supply is circulated at a predetermined pressure and a predetermined flow rate (flow rate). In the low-pressure economizer, the feedwater is heated to about 150 ° C to 160 ° C, and the water in the circulating water supply path is similarly high in temperature. ) To prevent erosion and corrosion in the piping. In the circulating water supply path of the low-pressure economizer, usually, alkali treatment is performed so that the PH becomes about 8.8 to 9.3. Normally, erosion / corrosion (erosion / corrosion) in the piping is prevented by the volatile substance treatment method (AVT), but erosion / corrosion (erosion / corrosion) still occurs in the piping, and is less than 20 to 30 μm. Fine crystallization particles of iron may be generated.
[0005]
[Patent Document 1] Japanese Patent Application Laid-Open No. 6-272805
[Problems to be solved by the invention]
As shown in FIG. 7, the solubility of iron ions becomes highest in the vicinity of 150 ° C. in relation to temperature, and becomes highest at PH 8.8 between PH 8.8 and PH 9.6, and the PH increases. As it gradually decreases. For this reason, the present inventors considered that, between PH 8.8 and PH 9.6, the smaller the PH, the higher the solubility of iron, and therefore, the higher the PH, the lower the solubility, and thought that corrosion could be suppressed.
[0007]
The present inventors conducted an experiment in which the pH of the circulating water supply path of the low-temperature economizer was increased to 9.6 to operate the exhaust heat recovery plant in order to prevent chemical corrosion from spreading. As a result, iron particles having a particle size exceeding 30 μm were generated in the circulating water supply path of the low-temperature economizer. The iron particles flowed out and diffused into a low-pressure system, a medium-pressure system, and a high-pressure system water supply path of the exhaust heat recovery plant, causing a problem of damaging seal members and valves of the exhaust heat recovery plant. If the waste heat recovery plant has an evaporator and a superheater, the water in the water supply path of the waste heat recovery plant is supplied to the superheated steam in the superheater to control the temperature of the steam in the superheater. There was a case. For this reason, the water containing iron particles was supplied to the superheater, causing a problem in the superheated steam system. Crystallized particles having a particle size of 30 μm or more in the circulating water supply path have never been present, and crystallized particles having a particle size of 30 μm or more in the circulating water supply path have a PH of 9.6. It is thought that this was the cause.
[0008]
Therefore, the present invention prevents the generation of large iron particles having a particle size of more than 30 μm and, even when the iron particles are generated, prevents the iron particles from diffusing into the downstream system, whereby The purpose is to eliminate such problems.
[0009]
[Means for Solving the Problems]
In the first plant used in the experiment by the present inventors, the flow rate in the low pressure economizer pipe was 0.06 m / s immediately after the start and 0 in the full operation state immediately after the start of the operation and during the plant full operation. .30 m / s, and a flow rate change of about 5 times occurred. In addition, the second plant used in the experiment by the present inventors also had a flow rate in the low-pressure economizer pipe of 0.25 m / s immediately after the start-up and during the plant full operation immediately after the start of the start-up. Was 1.24 m / s, and a flow rate change of about 5 times occurred. The present inventors have investigated and found that the iron concentration increased during the plant full operation immediately after the start of the start, but did not increase when the flow velocity was stabilized in the full operation state, and gradually decreased. In addition, the present inventors have found that there is a relationship shown in FIG. 5 between the flow rate, the temperature, and the amount of corrosion with respect to the corrosion of the piping in the circulating water supply path of the low-temperature economizer.
[0010]
Based on these findings, the present inventors have found that in the circulating water supply path of a low-temperature economizer, as the flow velocity increases, erosion, which is a physical damage phenomenon, occurs, and where the protective coating is peeled off due to this erosion. It was considered that a phenomenon called flow accelerated corrosion, in which corrosion, which is a chemical damage phenomenon, occurs in the steel. FIG. 6 schematically illustrates flow accelerated corrosion. The flow accelerated corrosion is described in Mizuno, "Thermal Nuclear Power Generation", Japan Society for Thermal and Nuclear Power Generation Technology, February 25, 2001, February 2001, pages P132 to P133.
[0011]
In addition, the present inventors have obtained, as a result of the experiment, a finding that the source of iron particles is mainly a low-pressure economizer operated at a temperature of 150 ° C to 160 ° C and a circulation water supply route thereof.
[0012]
Since the temperature is close to 150 ° C. in the circulation path of the low-pressure economizer, there is an environment in which iron ions are most easily eluted by flow accelerated corrosion. In addition, since the feedwater is circulating, the concentration of iron ions eluted by the flow accelerated corrosion is likely to be high, and this is an environment in which iron ions are likely to be in a supersaturated state. In such an environment, as a result of an operation in which the pH was increased to 9.6, iron ions eluted by the flow accelerated corrosion were crystallized in the circulating water supply path, and the crystallized iron particles grew, Was found to have iron particles of 30 μm or more.
[0013]
The present inventors have considered the circumstances in which iron particles are generated as described above, and have come up with the following invention.
[0014]
First, the iron ion crystallization suppression system according to the present invention adjusts the pH of the circulation path to 9.30 to 9.45 in a heating device that heats the water in the circulation path under pressure. It is characterized in that crystallites of iron ions are prevented from growing in the circulation path. Thereby, the solubility is slightly increased as compared with the case of PH 9.6, so that the crystallization of iron ions can be suppressed, and the growth of crystallized iron particles can be suppressed. In addition, since the solubility of iron ions is lower than in the case of pH 8.8 to PH 9.3, elution of iron ions by flow accelerated corrosion can be suppressed, and the iron ions are prevented from becoming supersaturated. be able to. Thereby, crystallization of iron ions and growth of crystallized iron particles can be suppressed, and generation of iron particles having a particle size exceeding 30 μm can be prevented. In this case, the PH is more preferably set to 9.30 to 9.40, and further preferably set to 9.35 to 9.40.
[0015]
Secondly, in the iron ion crystallization suppression system according to the present invention, in the heating device for heating the water in the circulation path under pressure, a filter for removing crystallized iron particles in the circulation path is provided. It is characterized by. This makes it possible to remove particles in the early stages of crystallization, which are the nuclei for the growth of the crystallized particles, thereby preventing the formation of iron particles having a particle size exceeding 30 μm. In addition, since the crystallized particles of iron can be captured by the generation source, the crystallized particles of iron can be prevented from diffusing into other pipes, and problems caused by the crystallized particles of iron can be eliminated.
[0016]
Thirdly, the iron ion crystallization suppression system according to the present invention comprises, in a heating device for heating the water in the circulation path in a pressurized state, an iron concentration measuring means for measuring an iron concentration in the circulation path; Iron concentration adjusting means for adjusting the iron concentration of the path, and control means for controlling the iron concentration adjusting means based on the measurement value of the iron concentration measuring means, so that the iron concentration of the circulation path is less than the solubility. It is characterized by having. As a result, the iron concentration in the circulation path can be reduced, so that crystallization of iron ions and growth of crystallized particles can be suppressed, and the generation of iron particles having a particle size exceeding 30 μm can be prevented. can do.
[0017]
In this case, the iron concentration adjusting means includes water supply means for supplying water to the circulation path, water supply amount adjustment means for adjusting the water supply amount, drainage means for draining water in the circulation path, and drainage amount adjustment means for adjusting the drainage amount. Preferably, the control means controls water supply and drainage of the circulation path based on the measurement value of the iron concentration measurement means so that the iron concentration of the circulation path becomes lower than the solubility. The above-mentioned means for suppressing crystallization of iron ions can also be used in combination to prevent crystallization and growth of iron ions.
[0018]
Further, the superheating plant according to the present invention is a heating device for heating the water in the circulation path in a pressurized state, an evaporator for heating the water supplied from the circulation path to generate steam, and supplied from the evaporator. In a superheated steam plant equipped with a superheater for superheating the heated steam and a temperature control device for controlling the temperature of the steam in the superheater, the temperature control means superheats the steam generated in the evaporator in the superheater. It is characterized by being supplied to According to this superheated steam plant, it is possible to prevent iron particles from diffusing into the steam system, and to prevent problems caused by iron particles in the steam system. In such a superheated plant, it is desirable to employ the above-described iron ion crystallization suppression system for the heating device.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an iron ion crystallization suppression system of the present invention will be described with reference to the drawings.
[0020]
In this embodiment, the iron ion crystallization suppression system according to the present invention is applied to a combined power generation plant in which a gas turbine, an exhaust heat recovery plant using exhaust heat of the gas turbine, and a steam turbine are combined.
[0021]
As shown in FIG. 1, this combined power generation plant 1 operates with a gas turbine 2, an exhaust heat recovery plant 3 that generates steam by using exhaust heat of the gas turbine 2, a steam turbine 4, and a steam turbine 4. A condenser 5 for returning the recovered steam to water, a condensate passage 6 for circulating the exhaust heat recovery plant 3, the steam turbine 4 and the condenser 5, and a condensate pump 7 for circulating water in the condensate passage 6. Have.
[0022]
As shown in FIG. 2, the exhaust heat recovery plant 3 uses the heat of the exhaust gas of the gas turbine 2 in stages from a high temperature stage to a low temperature stage. In order, high-pressure superheater 12, reheater 13, high-pressure evaporator 14, high-pressure economizer 15, medium-pressure superheater 16, low-pressure superheater 17, medium-pressure evaporator 18, medium-pressure economizer 19, high-pressure primary section A charcoal unit 15 ', a low-pressure evaporator 20, and a low-pressure economizer 21 are provided. In this embodiment, the steam turbine 4 includes a high-pressure steam turbine 4a, a medium-pressure steam turbine 4b, and a low-pressure steam turbine 4c. In the drawing, reference numeral 7 denotes a condensate pump.
[0023]
The low-pressure economizer 21 has a circulating water supply path 22 and heats the water supplied from the condenser 5 while circulating the water. A pressure of about 3 MPa is applied to the circulation water supply path 22 by the circulation pump 23. The water discharged from the low-pressure economizer 21 to the circulating water supply path 22 has a temperature of about 150 ° C. to 160 ° C. Part of the water heated by the low-pressure economizer 21 is supplied to the low-pressure evaporator 20, another part is supplied to the medium-pressure system or high-pressure system by pipes 24 and 25, and the rest is returned to the circulation water supply path 22 again. ing. Then, the water supplied from the condenser 5 is mixed with the water returned to the circulating water supply path 22 again to about 60 ° C. and supplied to the low-pressure economizer 21 again.
[0024]
The circulation water supply path 22 is provided with a medicine supply means 26 for supplying a PH adjustment medicine (for example, ammonia) in order to adjust the pH in the circulation water supply path 22. In this embodiment, the dosage of the medicine is controlled so that the PH in the circulating water supply path 22 becomes 9.30 to 9.45. In this embodiment, the medicine introduction means 26 includes a medicine tank 26a, a medicine introduction pump 26b, a PH measurement device 26c (for example, an electric conductivity measurement device) for measuring the condensed water PH after the medicine introduction, and a PH measurement A control device 26d is provided which operates the medicine supply pump 26b based on the measurement result of the device 26c to adjust the amount of medicine to be supplied. In this embodiment, the PH of the condensed water after the introduction of the medicine is measured by the PH measurement device 26c, and the measurement result is fed back to the operation of the medicine introduction pump 26b by the control device 26d. The present invention is not limited to this. For example, the pH of the circulating water in the circulating water supply path 22 may be measured, and the measurement result may be fed back to the chemical injection pump 26b.
[0025]
As a result of adjusting the pH in the circulation water supply passage 22, the crystallization phenomenon of iron ions in the circulation water supply passage 22 was able to be suppressed. In particular, no crystallized iron particles having a grain size of about 30 μm were generated as compared with the prior art. Thereby, it was possible to prevent a problem that the iron particles flowed out to another water supply path of the exhaust heat recovery plant 3 and damaged the seal member and the valve of the exhaust heat recovery plant 3. This is because by setting the pH to 9.30 to 9.45, the solubility becomes higher as compared with the pH of 9.60, the crystallization of iron ions is suppressed, and the particle size of the crystallized iron particles is 30 μm. Growth can be suppressed as described above.
[0026]
That is, in this embodiment, the crystallization of iron ions and the growth of the crystallized iron particles are suppressed by setting the pH of the circulation water supply path 22 to 9.30 to 9.45. When the pH in the circulation water supply passage 22 was controlled to be 9.4 and its vicinity, the effect of suppressing the crystallization phenomenon of iron ions and the growth of iron particles crystallized with iron ions was better. .
[0027]
As described above, the iron ion crystallization suppression system according to the first embodiment can suppress fluid accelerated corrosion, and can suppress crystallization of iron ions and growth of crystallized iron particles. By adjusting the pH of the circulating water supply path to an appropriate range, crystallization of iron ions and growth of crystallized iron particles can be suppressed.
[0028]
Next, in the iron ion crystallization suppression system according to the second embodiment, as shown in FIG. 3, a circulating water supply path 22 is provided with a filter 31 for removing crystallized particles of iron. The filter 31 has a function of capturing crystallized particles of iron having a predetermined particle size (for example, 10 μm or more), and may be a metal filter, a ceramic filter, an electromagnetic filter, a centrifugal separator, or the like. And "Metal Membrane Filter", "Porous Metal Filter", and "Metal Fiber Filter" manufactured by Pall Corporation. In addition, when there are temperature restrictions such as a condition that the filter 31 cannot withstand a temperature of about 150 ° C. (for example, when using a heat-flexible plastic resin fiber), A filter 31 may be installed between the inlet of the circulating water supply path 22 where water from the condenser 5 flows and the inlet of the low-pressure economizer 21.
[0029]
When the filter 31 is provided in the circulation water supply path 22 in this manner, the filter 31 can capture the crystallized iron particles having a particle size of about 10 μm, which are nuclei of crystallization (nuclei of iron particle growth). Therefore, it is possible to prevent crystallization particles of iron having a particle size of about 30 μm from being generated in the circulation water supply path 22.
[0030]
By providing the filter 31 in this way, it is possible to prevent the generation of crystallized iron particles having a particle size of about 30 μm. Therefore, it is necessary to increase the PH in the circulation water supply passage 22 to about 9.6 or more. Can be. That is, if the filter 31 is provided and the PH is set to about 9.6 or more, it is possible to prevent problems caused by iron crystallization particles and to suppress the amount of corrosion due to an increase in solubility.
[0031]
Next, as shown in FIG. 4, the iron ion crystallization suppression system according to the third embodiment includes an iron concentration measurement unit (not shown) that measures the iron concentration of the circulation water supply path 22, and circulates from the circulation water supply path 22. A discharge unit 32 for discharging the water being discharged, a discharge adjusting unit 33 for adjusting the discharge amount of the water discharged from the discharge unit 32, and a circulating water supply path 22 based on the iron concentration measured by the iron concentration measuring unit. And a control means 34 for appropriately controlling the discharge amount discharged from the discharge section 32 so that the iron concentration becomes equal to or lower than the solubility. The iron concentration measuring means measures the iron concentration in the circulating water supply path 22 by periodically sampling the water in the circulating water supply path 22 (for example, every 30 minutes or every hour) to grasp the current state of the iron concentration. Means for estimating changes over time in iron concentration can be used.
[0032]
In the iron ion crystallization suppression system according to the third embodiment, when the iron concentration in the circulating water supply path 22 increases, before the supersaturation, the control unit 34 adjusts the discharge amount while controlling the discharge amount from the discharge unit 32. Water containing iron ions and fine crystallized particles of iron is discharged, and more water flows from the condenser 5 into the circulation water supply path 22. Thereby, the iron concentration of the water in the circulating water supply path 22 is reduced by the water flowing from the condenser 5, and the iron concentration can be reduced to the solubility or less. That is, the environment in which iron ions hardly crystallize and the environment in which iron crystallized particles are unlikely to grow can be made in the circulation water supply passage 22, so that iron crystallized particles having a particle size of about 30 μm are generated. Can be prevented.
[0033]
At this time, if the iron concentration is excessively lowered, a state in which the iron is easily corroded by flow accelerated corrosion is obtained. Therefore, the iron concentration may be controlled to be about 95 to 80% of the saturation solubility.
[0034]
Further, by providing the means for adjusting the iron concentration in the circulating water supply passage 22 as described above, it is possible to prevent the generation of iron crystallization particles having a particle diameter of about 30 μm. .6 or higher. That is, by providing a means for adjusting the iron concentration, and by setting the pH to about 9.6 or more, it is possible to suppress the flow accelerated corrosion and to prevent the trouble caused by the growth of crystallized iron particles. Can be.
[0035]
In addition, in order not to lower the thermal efficiency of the waste heat recovery plant 3, the water discharged from the discharge unit 32 may exchange heat with the water supplied from the condenser 5.
[0036]
The iron ion crystallization suppression systems of the first to third embodiments have the effect of independently preventing the generation and growth of iron crystallization particles. Particle generation and growth can also be prevented.
[0037]
The iron ion crystallization suppression system according to one embodiment of the present invention has been described above, but the iron ion crystallization suppression system according to the present invention is not limited to the above embodiment.
[0038]
In the above embodiment, the embodiment applied to the combined power generation plant is described. However, the iron ion crystallization suppression system according to the present invention is not limited to the combined power generation plant, and various types of heating for heating water in the circulation path may be used. The present invention can be applied to an apparatus (in particular, a heating apparatus that heats water in a pressurized state), and can be applied to, for example, an exhaust heat recovery plant such as a garbage incineration plant.
[0039]
Next, a superheated steam plant according to an embodiment of the present invention will be described.
[0040]
Some superheated steam plants include a circulation water supply path as described above, an evaporator for producing steam from supplied water, and a superheater for producing superheated steam from the vapor of the evaporator. (For example, each of the exhaust heat recovery plants shown in FIGS. 2 to 4 is configured as a superheated steam plant that supplies superheated steam to a steam turbine.)
[0041]
Conventionally, in such a superheated steam plant, in order to control the temperature of the steam in the superheater, a spray device that sprays water in a water supply path of the evaporator in the superheater and a temperature of the steam in the superheater are used. It had a temperature controller with a controller to activate the sprayer in a timely manner. However, in the temperature control device described above, when iron particles having a particle size of 30 μm or more are generated in the circulation water supply path, the iron particles enter the superheater via the spray device, and the steam system downstream from the superheater is used. Iron particles may diffuse into the steam system and cause problems in the steam system.
[0042]
For this reason, the superheated steam plant according to the present invention, as shown in FIGS. 2 to 4, takes out part A and B of the steam generated in the evaporator and supplies it to the spray device of the temperature control device provided in the superheater. I did it. According to this superheated steam plant, since the steam generated in the evaporator containing no iron particles is supplied to the temperature control device, it is possible to prevent the iron particles from diffusing into the steam system. Thus, it is possible to reliably prevent the occurrence of a problem caused by iron particles in the steam system. In particular, as shown in FIGS. 2 to 4, the superheated plant according to the present invention is caused by iron particles in both the water supply system and the steam system of the superheated steam plant by using the iron ion crystallization suppression system described above. It is possible to reliably prevent the occurrence of a failure.
[0043]
【The invention's effect】
According to the iron ion crystallization suppression system according to the present invention, it is possible to suppress the generation and growth of iron crystal particles in the circulation path in various heating devices that heat the water in the circulation path in a pressurized state. In addition, it is possible to prevent various problems caused by iron crystallization particles. Further, according to the superheated steam plant according to the present invention, since the steam generated in the evaporator is taken out and supplied to the temperature control device provided in the superheater, the iron particles are prevented from diffusing into the steam system. can do.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a combined power generation plant.
FIG. 2 is a diagram showing an iron ion crystallization suppression system according to the first embodiment.
FIG. 3 is a diagram showing an iron ion crystallization suppression system according to a second embodiment.
FIG. 4 is a diagram showing an iron ion crystallization suppression system according to a third embodiment.
FIG. 5 is a diagram showing a relationship among a flow rate, a temperature, and a corrosion amount.
FIG. 6 is a schematic view of flow accelerated corrosion.
FIG. 7 is a graph showing a relationship between solubility of iron ions, temperature and PH.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Combined power generation plant 2 Gas turbine 3 Exhaust heat recovery plant 4 Steam turbine 5 Condenser 6 Condensate flow path 7 Condensate pump
11 Exhaust stack
21 Low pressure economizer
22 Circulation water supply route
23 Circulation pump
26 Drug injection means
31 filters
32 discharge section
33 Emission adjustment means
34 Control means

Claims (6)

In the heating device for heating the water in the circulation path in a pressurized state, the pH of the circulation path is adjusted to 9.30 to 9.45 to suppress the growth of crystal particles of iron ions in the circulation path. An iron ion crystallization suppression system characterized in that: An iron ion crystallization suppression system, characterized in that a heating device that heats water in a circulation path under pressure is provided with a filter for removing crystallized particles of iron in the circulation path. In a heating device for heating water in a circulation path in a pressurized state, iron concentration measurement means for measuring iron concentration in the circulation path, iron concentration adjustment means for adjusting iron concentration in the circulation path, and said iron concentration measurement means Control means for controlling the iron concentration adjusting means such that the iron concentration in the circulation path is equal to or lower than the solubility based on the measured value of the iron ion crystallization. The iron concentration adjusting means includes a water supply means for supplying water to the circulation path, a water supply amount adjustment means for adjusting the water supply amount, a drainage means for draining water in the circulation path, and a drainage amount adjustment means for adjusting the drainage amount, 4. The iron ion according to claim 3, wherein the control unit controls water supply and drainage in the circulation path based on the measurement value of the iron concentration measurement unit such that the iron concentration in the circulation path is equal to or lower than the solubility. 5. Crystallization control system. A heating device that heats the water in the circulation path in a pressurized state, an evaporator that heats the water supplied from the circulation path to generate steam, and a superheater that superheats the steam supplied from the evaporator. In a superheated steam plant comprising a temperature control device for controlling the temperature of steam in the superheater,
A superheated steam plant, wherein the temperature control means supplies steam generated in the evaporator to steam superheated in a superheater. The superheated steam plant according to claim 5, wherein the heating device includes the iron ion crystallization suppression system according to any one of claims 1 to 4.

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