JP3667525B2 - Steam generator-attached nuclear power generation turbine facility - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention Oite to the steam generator incidental type nuclear power plant, material maintaining sound relates configured steam generator incidental nuclear power turbine equipment to be able to improve.
[0002]
[Prior art]
Oite to the steam generator incidental nuclear power plants, it has as much as possible to reduce the amount of deposition of iron into the heat transfer tube the secondary side in order to maintain the heat transfer tube secondary side of the material soundness of the steam generator The As a method for this, in order to suppress the functional degradation due to the corrosion of the equipment and piping of the turbine equipment, in recent years, volatile chemical treatment (hereinafter referred to as AVT) has been adopted to suppress the corrosion of the turbine system.
[0003]
In VT, the pH is usually kept at about 8.7 to 9.5 by adding ammonia, and 0.2 to 0.6 ppm of hydrazine is added to the feed water, and the deoxygenation is controlled to keep the concentration of water supply oxygen in the feed water almost zero by installing a deaerator. Or you are driving in a reducing atmosphere.
[0004]
However, by reducing the dissolved oxygen, the corrosion of the entire material surface is suppressed, but erosion and corrosion accelerated by running water are generated, which may impair the soundness of equipment and piping.
[0005]
In some steam generator-attached nuclear power plants, a high AVT with a further increased pH may be employed from the viewpoint of inhibiting corrosion. In this case, if the condensate demineralizer is used during normal operation, it will not be used because it captures chemicals used for corrosion control and the regeneration frequency is not in time for operation management. For this reason, the corrosive matter generated upstream of the condensate system flows downstream.
[0006]
According to the following literature, the iron concentration of feed water is about 2.3ppb [HGHEITMANN etal; Initial experience gained with a high pH value in the secondary system of PWRs, BNES LONDON Water Chemistry Nuclear systems, 1983] .
[0007]
[Problems to be solved by the invention]
Even if AVT is adopted in the steam generator-attached nuclear power plant, the feedwater iron concentration is about several ppb. Therefore, in the steam generator-attached nuclear power plant, the amount of iron oxide deposited in the steam generator There is a problem that intergranular corrosion damage (IGA) occurs on the secondary side of the steam generator heat transfer tube due to the increase in concentration of impurities.
[0008]
Even with the recent high AVT at steam generator-attached nuclear power plants and the adoption of the CWT method at thermal power plants, the amount of chemicals used is enormous and the cost of chemical management is high, and there are concerns about pollution. Is also expensive. Furthermore, the frequency of chemical regeneration of the condensate demineralizer resin is high, the amount of regenerated chemicals generated is large, and there is a problem that its management is costly.
[0009]
The present invention has been made to solve the above-described problems, and is associated with a steam generator that can reduce the concentration of water supply iron, maintain the soundness of the material, and improve it at a low management cost without using chemicals. It aims at providing the turbine equipment for type nuclear power generation.
[0010]
[Means for Solving the Problems]
Corresponding to claims 1 invention, the steam generator or we generated steam used to steam generator incidental nuclear power leads through the main steam pipe to the turbine system, a generator by rotating a turbine of the turbine system Steam generated after driving and condensing in the turbine system is condensed and condensed in a condensate condenser, and the condensed water is purified by a condensate purification system and heated by a feed water heater. In the steam generator-attached nuclear power generation turbine facility for returning the feed water to the steam generator or boiler, the water supply is adjusted to neutral pure water and the dissolved oxygen concentration is adjusted to 7 ppb or more, and the steam generator Alternatively, a corrosion-resistant material is incorporated into a part of equipment and piping from the boiler to the water supply system.
[0011]
The invention corresponding to claim 2 is characterized in that the feed water iron concentration of the feed water system is 1 ppb or less. The invention corresponding to claim 3 is characterized in that an oxygen gas supply pipe is connected to an upstream pipe of the low pressure feed water heater of the main steam pipe and the feed water system.
[0012]
The invention corresponding to claim 4 is characterized in that the corrosion resistant material is made of weathering steel, low alloy steel or stainless steel. In the invention corresponding to claim 5, the condensate purification system has at least one of a condensate filter or a condensate demineralizer, and the condensate filter is a hollow fiber membrane filter, a non-precoated filter, or a powder ion exchange. It consists of any one of resin filters.
[0013]
In the invention corresponding to claim 6, the discharge side piping of the condensate pump of the condensate system and the low pressure heater drain side of the low pressure feed water heater of the feed water system are returned upstream from the low pressure heater drain pipe, the low pressure heater drain pump and the hollow fiber membrane filter. are connected to one another through pipes, characterized by comprising connecting the upstream return line and downstream return line of the hollow fiber membrane filter upstream return pipe with condensate demineralizer above flow pipe of the low-pressure feed water heater.
[0014]
Corresponding to claim 7 invention is characterized by formed by connecting the noble metal injection apparatus into the steam generator. According to an eighth aspect of the present invention, a hydrogen gas supply device is connected to the downstream water supply system piping of the condensate demineralizer, and the corrosion potential on the secondary side of the steam generator is maintained at an amount of −200 mV or less. It is characterized by.
[0015]
According to the present invention, in order to maintain and improve the material soundness of the turbine equipment, the iron supply water concentration is reduced under neutral pure water conditions without using chemicals. In FIG. 3, it is clear that the corrosion of carbon steel is suppressed when dissolved oxygen is present. It is known that the corrosion inhibition is due to the formation of a stable oxide film of Fe ₂ O _{3 in} the presence of dissolved oxygen.
[0016]
FIG. 3 is quoted from the literature of Gordon etal, “Hydrogen water chemistry for BWRs” EPRI NP-3935M (1985), and 1000 hr at different oxygen concentrations in the temperature range of 200 to 300 ° C. (392 to 572 F °). It shows the corrosion rate and dissolution rate of the exposed carbon steel in relation to the dissolved oxygen concentration.
[0017]
According to FIG. 4, when dissolved oxygen is 7 ppb or more, it is clarified that corrosion accelerated by flow rate, so-called erosion and corrosion (FAC: Flow-Accelerated Corrosion) is suppressed.
[0018]
FIG. 4 shows the effect of dissolved oxygen on the corrosion wear accelerated by the flow rate. The vertical axis shows the increase in the corrosion wear rate accelerated by the flow rate, and the horizontal axis shows the dissolved oxygen (ppb).
[0019]
Figures 5 to 7 show “Thermal Power Generation: Corrosion and Prevention of Power Plants, Corrosion Form and Countermeasure 2” vol. 6 From p677 to Jun. 1996, it has been clarified that low carbon steel has extremely higher erosion resistance and corrosion resistance than carbon steel.
[0020]
That is, FIG. 5 shows the effect on erosion and corrosion weight loss for carbon steel, Ni—Cr—Cu steel and Cr—Mo steel, FIG. 6 shows the effect of steam wetness, and FIG. It shows the effect of steam humidity on erosion and corrosion weight loss for Cr-Mo steel.
[0021]
In the present invention, when the heater drain system is a cascade system, the concentration of dissolved oxygen in the steam and water is increased by injecting oxygen gas or air into the steam system, and a dense oxide film is formed on the inner surface of the equipment and piping. By doing so, the corrosion of the inner surface of equipment and piping is suppressed. Moreover, the iron brought in from the upstream in the condensate purification system is almost completely removed, and further, the generation of iron from the water supply system is suppressed by injecting oxygen gas so that the iron brought in from the water supply system is 1 ppb or less. be able to.
[0022]
On the other hand, in the case of a forward drain system, oxygen gas or air is injected into the steam system to increase the dissolved oxygen concentration in the steam and water, and to form a dense oxide film on the inner surface of the equipment and piping and corrosion resistant material In addition to further suppressing corrosion of equipment and the inner surface of piping by using, the concentration of feedwater iron is reduced to 1 ppb or less by suppressing the generation of iron from the feedwater system by installing a condensate purification system and injecting oxygen gas . When LPPD has a high iron concentration, LPPD is recovered upstream of the condensate purification system, and the iron is almost completely removed, so that the feedwater iron concentration can be reduced to 1 ppb or less.
[0023]
Furthermore, in the steam generator-attached nuclear power plant, the corrosion potential on the secondary side of the steam generator heat transfer tube is set to -200 mV or less by injection of feed water hydrogen gas to suppress the generation of IGA. In order to reduce the feed water hydrogen gas injection amount, it is possible to suppress the generation of IGA by plating or coating a noble metal on the secondary surface of the steam generator heat transfer tube or injecting a noble metal solution under high temperature conditions.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of a steam generator-attached nuclear power generation turbine facility according to the present invention will be described with reference to FIG. In Figure 1, reference numeral 1 is a steam generator. The steam generator 1 has a built-in heat transfer tube 27, the main steam pipe 2 is connected to the steam generator 1. The main steam pipe 2 is connected to a high-pressure turbine 3 of a turbine system, and a moisture separator 4, a reheater 5 and a low-pressure turbine 6 are sequentially connected downstream of the high-pressure turbine 3.
[0025]
The low-pressure turbine 6 is provided with a condensate main condenser 7, a condensate pump 8 is connected to the downstream side of the main condenser 7, and the discharge side of the condensate pump 8 is a condensate hollow as a filtration device. It is connected to a thread membrane filter (hereinafter referred to as HFF) 9. A low-pressure feed water heater 10, a feed water pump 11, and a high-pressure feed water heater 12 are sequentially connected to the downstream feed water system of the HFF 9, and the downstream side of the high-pressure feed water heater 12 is connected to the steam generator 1 by a feed water pipe 13. .
[0026]
A secondary side inlet of the high pressure feed water heater 12 is connected to an extraction pipe 14 connected to the high pressure turbine 3, a moisture separator drain pipe 15 and a reheater drain pipe 16 connected to the reheater 5. A high pressure heater drain pipe 17 connected to the suction side of the feed water pump 11 is connected to the secondary side outlet of the high pressure feed water heater 12 via a high pressure heater drain pump 18.
[0027]
A bleed pipe 19 connects between the low pressure turbine 6 and the secondary side inlet of the low pressure feed water heater 10. The secondary outlet of the low pressure feed water heater 10 and the discharge side pipe of the HFF 9 are connected via a low pressure heater drain pump 21 by a low pressure heater drain bypass pipe (hereinafter referred to as LPPD) 20.
[0028]
Here, in FIG. 1, reference numeral 22 denotes an oxygen gas or air supply device 22, which is connected to the upstream side of the main steam pipe 2 through a main steam system pressurizing pump 23 and is connected to the water supply system. It is also connected to the inlet side water supply system piping of the low pressure feed water heater 10 through the pressure pump 24 for use. Reference numeral 25 denotes a hydrogen gas supply device. The hydrogen gas supply device 25 is connected to a downstream water supply system pipe of the HFF 9 via a hydrogen gas pressurizing pump 26.
[0029]
Reference numeral 28 denotes a corrosion potential meter, which is connected to the steam generator 1 and the liquid in the steam generator 1 flows into the corrosion potential meter 28 by a pump and is measured. Reference numeral 29 denotes a noble metal injection device, which is connected to the lower portion of the steam generator 1 via a pump. Reference numeral 30 denotes an exhaust gas system, which is connected to the main condenser 7 via a pump. The exhaust gas system 30 is provided with an exhaust gas recombiner 31, and its downstream side is connected to an exhaust pipe (stack).
[0030]
Here, the steam generated in the steam generator 1 passes through the main steam pipe 2 and rotates the high-pressure turbine 3, and then the moisture is separated by the moisture separator 4. Then, it is reheated by the reheater 5, flows into the low pressure turbine 6, rotates the low pressure turbine 6, and drives a generator (not shown). The steam that has finished its work is condensed by the main condenser 7 containing a titanium cooling pipe, for example, and becomes condensate.
[0031]
The condensate is sent from the main condenser 7 to the HFF 9 having a 100% condensate purification capacity by the condensate pump 8, and the condensate cladding is almost removed. The condensate purified by the HFF 9 becomes feed water heated by the low pressure feed water heater 10 and the high pressure feed water heater 12, passes through the feed water pipe 13, and is supplied to the steam generator 1 by the feed water pump 11. In this way, the steam generated in the steam generator 1 repeats a cycle that follows the turbine system, the condensate system, and the water supply system.
[0032]
During this cycle, the bleed air from the high pressure turbine 3 used as a heat source for the high pressure feed water heater 12 flows through the bleed pipe 14 into the high pressure feed water heater 12. Further, the drain of the moisture separator 4 flows into the high-pressure feed water heater 12 through the drain pipe 15. Further, the drain of the reheater 5 flows into the high-pressure feed water heater 12 through the drain pipe 16. The drain 17 condensed by exchanging heat with the feed water system piping by the high pressure feed water heater 12 is collected upstream of the feed water pump 11 by the high pressure heater drain pump 18 in order to improve heat recovery.
[0033]
On the other hand, the bleed air from the low-pressure turbine 6 as a heat source for the low-pressure feed water heater 10 is supplied to the low-pressure feed water heater 10 through the bleed pipe 19, and then the heat-exchanged drain 20 passes through the LPPD 20 to improve heat recovery. It is recovered downstream of the HFF 9 by the low pressure heater drain pump 21.
[0034]
Oxygen gas or oxygen gas supplied from the air supply device 22 to the main steam pipe 2 immediately after flowing out of the steam generator 1 in order to suppress corrosion downstream of the HFF 9 and corrosion of turbine equipment flowing downstream of the HFF 9 Alternatively, air is supplied by the pressurizing pump 23 so that the main steam, the bleed air and the heater drain have an appropriate dissolved oxygen concentration.
[0035]
On the other hand, the oxygen gas or air supplied from the oxygen gas supply device 22 is supplied to the downstream of the HFF 9 by the pressurizing pump 24 so that the condensate and the supply water have an appropriate dissolved oxygen concentration. Furthermore, in order to reduce the absolute amount of corrosion, the steam system and drain system equipment and pipes that flow downstream of the HFF 9 excluding the condensate pipe and the feed water pipe are made of low alloy steel, and the reheater 5 and feed water heater The heat transfer tubes 10 and 12 are made of stainless steel.
[0036]
As a result, all the turbine systems that flow into the downstream side of the HFF 9 and serve as feed water form a dense oxide film and the corrosion is suppressed, whereby the feed water iron concentration can be maintained at a low level of 1 ppb or less.
[0037]
In addition, the corrosion potential of the steam generator heat transfer tube 27 of the hydrogen gas supplied from the hydrogen gas supply device 25 is reduced to −200 mV or less as the indicated value of the corrosion potential meter 28 branched from the steam generator 1 by the pressurizing pump 26. So that it is supplied downstream of the HFF 9.
[0038]
Further, the noble metal solution is injected into the steam generator 1 by the noble metal solution injection device 29, and the noble metal is adhered to the surface of the steam generator heat transfer tube 27, thereby promoting the reaction between the supplied oxygen gas and the supplied hydrogen gas, and the hydrogen gas supply amount. Can be saved. On the other hand, the hydrogen gas and oxygen gas supplied can be safely treated by installing the exhaust gas recombiner 31 for reacting hydrogen gas and oxygen gas in the exhaust gas system 30 and returning it to water.
[0039]
According to the present embodiment, not only can the material soundness of the steam generator heat transfer tube 28 be maintained and improved, but also the economics of not using chemicals and the impact on the human body and the environment become gentle. This is preferable.
[0040]
A second embodiment of the steam generator-attached nuclear power generation turbine facility according to the present invention will be described with reference to FIG. This embodiment differs from the first embodiment in that a condensate demineralizer 32 is connected to the downstream side of the HFF 9, and a condensate demineralizer bypass pipe 33 is provided before and after the condensate demineralizer 32. At the same time, the HFF upstream return pipe 34 is provided between the LPPD 20 connected to the secondary side of the low-pressure feed water heater 10 and the discharge side pipe of the condensate pump 8.
[0041]
The HFF upstream return pipe 34 is connected with a condensate demineralizer upstream return pipe 35 via an upstream return valve 38 to a downstream pipe of the HFF 9, and the condensate demineralizer downstream return pipe 36 is a downstream return valve 39. There is a connection through.
[0042]
In the present embodiment, the condensate demineralizer 32 installed downstream of the HFF 9 is a mixed bed condensate demineralizer using a granular ion exchange resin. This condensate demineralizer 32 can remove impurities mixed during the turbine plant for power generation during condensate and feed water purification before plant start-up, suppress deterioration of reactor water quality at the beginning of plant start-up, and maintain extremely high purity. it can. It is also possible to cope with seawater leaks. Further, rational operation can be performed by bypassing the condensate demineralizer 32 using the bypass line 33.
[0043]
In addition, the iron concentration of LPPD 20 becomes high depending on the plant start-up, and when the feed water iron concentration can exceed 1 ppb, the return of LPPD 20 is performed between upstream of HFF 9 or between upstream of HFF 9 and condensate demineralizer 32. Or, valves 37, 38, 39 are installed so that they can be returned anywhere downstream 36 of the condensate demineralizer 32. By switching these valves, it is possible to operate rationally so that the feedwater iron concentration is 1 ppb or less. .
[0044]
It should be noted that the HFF upstream return pipe 34, the HFF 9, the condensate demineralizer upstream return pipe 35, and the condensate demineralizer downstream return pipe 36 can be configured with a minimum combination for rationalization of the plant.
[0045]
【The invention's effect】
According to the present invention, in a steam generator-attached nuclear power generation turbine facility, neutral pure water can be used for feed water without using chemicals, and the feed water iron concentration can be maintained at a low level of 1 ppb or less. The corrosion potential on the secondary side of the generator heat transfer tube can be set to -200 mV or less, and not only can the material soundness of the steam generator heat transfer tube be maintained and improved, but also the economics due to the absence of chemicals. Along with the improvement, the human body and the environment can be adversely affected.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a first embodiment of a steam generator-attached nuclear power generation turbine facility according to the present invention.
FIG. 2 is a system diagram showing a second embodiment of the steam generator-attached nuclear power generation turbine facility according to the present invention.
FIG. 3 is a curve diagram showing the corrosion inhibition effect of a dissolved oxygen material for comparing the operation of the present invention with a conventional example.
FIG. 4 is a curve diagram showing the influence of dissolved oxygen on corrosion wear that is excessively accelerated at a flow rate.
FIG. 5 is a curve diagram showing the influence of the steam flow rate on the erosion and corrosion loss of the corrosion resistant material.
FIG. 6 is a curve diagram showing the effect of steam wetness on erosion and corrosion weight loss of corrosion resistant materials.
FIG. 7 is a curve diagram showing the influence of steam humidity on erosion and corrosion weight loss of the corrosion-resistant material.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Steam generator, 2 ... Main steam pipe, 3 ... High pressure turbine, 4 ... Moisture separator, 5 ... Reheater, 6 ... Low pressure turbine, 7 ... Main condenser, 8 ... Condensate pump, 9 ... Condensate hollow fiber membrane filter (HFF), 10 ... low pressure feed water heater, 11 ... feed water pump, 12 ... high pressure feed water heater, 13 ... feed water pipe, 14 ... bleed pipe, 15 ... humidity separator drain pipe, 16 ... Reheater drain pipe, 17 ... high pressure heater drain pipe, 18 ... high pressure heater drain pump, 19 ... bleeder pipe, 20 ... low pressure heater drain bypass pipe (LPPD), 21 ... low pressure heater drain pump, 22 ... oxygen gas or air supply device , 23 ... Main steam pressurization pump, 24 ... Water supply system, 25 ... Hydrogen gas supply device, 26 ... Hydrogen gas pressurization pump, 27 ... Heat transfer tube, 28 ... Corrosion potential meter, 29 ... Precious metal injection device, 30 ... Exhaust gas System 31 ... exhaust gas recombiner 32 ... condensate demineralizer 33 ... condensate demineralizer bypass pipe 34 ... HFF upstream return Pipe, 35 ... Condensate demineralizer upstream return pipe, 36 ... Condensate demineralizer downstream return pipe, 37 ... HFF upstream return valve, 38 ... Condensate demineralizer upstream return valve, 39 ... Condensate demineralizer downstream Return valve.

Claims (8)

The steam generator or we generated steam used to steam generator incidental nuclear power leads through the main steam pipe to the turbine system, a generator and the generator is driven by rotating a turbine of the turbine system, the turbine system Condensed steam is condensed by a condenser condenser of the condensate system, and the condensate is purified by a condensate purification system, and heated by a feed water heater of the feed water system to supply water. in power generating turbine equipment to return to a steam generator or boiler, the water supply was adjusted dissolved oxygen concentration in the neutral pure water than 7 ppb, the steam generator or al the up feed water system equipment, resistance to a part of the pipe Steam generator-attached nuclear power generation turbine facility characterized by incorporating ingredients.   The power generation turbine equipment according to claim 1, wherein the feed water concentration of the feed water system is 1 ppb or less. The steam generator-attached nuclear power generation turbine equipment according to claim 1, wherein an oxygen gas supply pipe is connected to an upstream pipe of the main steam pipe and the low-pressure feed water heater of the feed water system. The steam generator-attached nuclear power generation turbine facility according to claim 1, wherein the corrosion-resistant material is made of weathering steel, low alloy steel, or stainless steel. The condensate purification system has at least one of a condensate filter or a condensate demineralizer, and the condensate filter is composed of any one of a hollow fiber membrane filter, a non-precoat filter, or a powder ion exchange resin filter. The steam generator-attached nuclear power generation turbine equipment according to claim 1. The discharge pipe of the condensate condensate pump and the low pressure heater drain side of the low pressure feed water heater of the feed water system are connected by a low pressure heater drain bypass pipe, a low pressure heater drain pump, and a hollow fiber membrane filter upstream return pipe. steam generator incidental type according to claim 1, characterized in that by connecting the upstream return line and downstream return line of the film filter upstream return pipe with condensate demineralizer above flow pipe of the low-pressure feed water heater Turbine equipment for nuclear power generation. The steam generator to the steam generator incidental nuclear power turbine equipment according to claim 1, characterized in that by connecting the noble metal injection devices. A hydrogen gas supply device is connected to the downstream water supply system piping of the condensate demineralizer, and the corrosion potential on the secondary side of the steam generator is maintained at an amount of −200 mV or less. The steam generator-attached nuclear power generation turbine facility according to claim 1.

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