JP2018009722A - Boiler plant and operating method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boiler plant and an operating method for the boiler plant, capable of shortening operation/storage switching time while reducing modification contents from a current plant as much as possible, when water quality of system water is managed by singly using ammonia.SOLUTION: A boiler plant (1) includes: a boiler (2) for generating steam by using heat from a heat source; a steam turbine (3) operated by using steam; a condenser (4) for condensing exhaust gas of the steam turbine to convert the exhaust gas into steam condensate; a water feed pump (5) for feeding the steam condensate condensed by the condenser to the boiler; an ammonia tank (20) for storing a predetermined concentration of an ammonia solution; and a pH increase promotion section (22) for guiding the ammonia into a system formed by sequentially interconnecting the boiler (2), the steam turbine (3), the condenser (4) and the water feed pump (5) to increase pH of system water to a pH range for boiler storage within a predetermined time.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a boiler plant and an operation method thereof.

  When a boiler plant equipped with a drum boiler and a waste heat recovery boiler (HRSG) is stored for several days or more due to shutdown, etc., dissolved oxygen in the feed water or boiler water becomes a corrosive factor for plant components. . Therefore, at the time of storage of a boiler plant, corrosion is prevented by using an anticorrosive agent (see Patent Document 1). As the anticorrosive, hydrazine having a deoxygenating ability is used.

  Conventionally, at the time of storage such as shutdown of a boiler plant, the operating water (feed water and boiler water) in the plant components is replaced with hydrazine water as storage water, and when the boiler plant is restarted, hydrazine is stored water. Work is being done to replace water with water for operation.

A large amount of pure water is used to replace hydrazine water and operation water. Since disposal of hydrazine water and operation water drained in the replacement work requires drainage treatment, replacement of hydrazine water and operation water becomes a factor of increasing the load on the wastewater treatment facility.
Furthermore, hydrazine has a problem in switching to operation water because it is a carcinogenic substance. For this reason, there is a need for a method for storing a boiler plant that can be diverted to operating water without draining stored water without using hydrazine, and can prevent corrosion of plant components over several days. .

  As a method of preventing corrosion of boiler plant components without using hydrazine, it is known to adjust the concentration of ammonia added to feed water and boiler water to increase the pH of feed water and boiler water as storage water. (See Patent Document 2). If the pH of the feed water and boiler water is set to 9.8 or higher, corrosion in the plant components can be prevented without adding hydrazine during normal operation of the boiler plant. For example, when the pH of the feed water and boiler water is 10, it becomes possible to store the boiler plant without adding hydrazine.

JP 62-233606 A JP 2014-159925 A

  The pH of feed water and boiler water can be defined by the amount of ammonia per unit volume. For example, the amount of ammonia per unit volume necessary for adjusting the pH to 9.8 is 5 mg / L. For example, the amount of ammonia per unit volume necessary for adjusting the pH to 10 is 12 mg / L.

In a circulation system of water such as boiler water and feed water (hereinafter, system water), plant loss occurs during circulation. Therefore, ammonia is injected into the system water to maintain the pH of the system water within a predetermined range. The plant loss is generally about 1% of the circulating water flow rate.
For example, the ammonia amount corresponding to the plant loss added to the system water of pH 9.8 is
0.05 mg / L (amount of ammonia per unit volume of system water: 5 mg / L × plant loss: 1%) (1)
It is.

  Based on the above, the maximum injection amount (12 mg / L) of ammonia is 240 times as large as the minimum injection amount (0.05 mg / L). It is difficult to cover this difference in capacity with a single pump while ensuring the accuracy of the ammonia injection amount. For example, when a plurality of pumps having different capacities are installed, it is necessary to use three types of pumps (corresponding to the startup, operation, and storage of the boiler plant), which increases costs.

Temporarily, the amount of system water held in the boiler plant system is 200 tonnes, the capacity of the feed water pump (circulation flow rate) is 400 ton / h, the concentration of the ammonia solution injected from the ammonia addition facility into the system water, for example, 1% by weight, and the pump Assuming that the minimum injection amount is 10% stroke,
The ammonia injection amount (minimum injection amount) required due to plant loss is 20 g / h.
(Circulating flow rate: 400 ton / h × plant loss: 1% × amount of ammonia per unit volume of system water: 5 mg / L) (2)
The ammonia solution injection rate is 2 L / h from equation (2).
(Ammonia: 20 g / h ÷ ammonia concentration: 1%)
The capacity required for the pump for injecting ammonia in this setting is 20 L / h.
(Ammonia solution 1 wt% injection rate: 2 L / h ÷ stroke: 10%) (3)
The amount of ammonia contained in 200 tons of system water is
When the pH of the system water is 9.8, 1,000 g
(System water volume: 200 ton × ammonia amount per unit volume: 5 mg / L)
When the pH of the system water is 10, 2,400 g
(System water amount: 200 ton × ammonia amount per unit volume: 12 mg / L)
It is.

Therefore, when storing the boiler plant in normal operation,
Difference in ammonia amount between pH 9.8 and pH 10 1,400 g
(2,400 g-1,000 g) of ammonia (4)
Need to be additionally injected into the system water volume of 200 tons in the boiler plant.

To inject 1,400 g (1.4 kg) of ammonia,
3.5 hours (1.4 kg / (20 L / h × 2 units × ammonia concentration 1%)) (5)
Cost.

The ammonia solution injected into the feed water is uniformly diffused into the system water by utilizing the circulation of the system water in the boiler plant system. However, since the circulation of the system water stops when the boiler stops, it is necessary to complete the additional injection of ammonia before stopping the operation of the boiler.
Therefore, when the pH of the system water is raised by such a method, from the formula (5), an ammonia solution of 1% by weight is injected into the system water at the maximum flow rate of two pumps from 3.5 hours before the boiler shutdown. There is room for improvement in operation.

  On the other hand, in order to change the pH of the system water after stopping the boiler, it is necessary to drain the system water outside the system and newly fill the system with the system water adjusted to the desired pH. It becomes a factor of cost increase, such as requiring a large amount of pure water.

  For this reason, as one method, it is possible to shorten the time required for adjusting the pH of the system water (3.5 hours according to equation (5)) by adding pumps, but the increase in plant components Therefore, it is preferable that the number of components is small.

  As another method, as a method of supplying a large amount of ammonia without increasing the number of pumps, it is conceivable to increase the concentration of the ammonia solution to reduce the amount injected into the system water. However, in the conventional ammonia addition equipment, the concentration of the ammonia solution is adjusted in the range of low concentration (1 to 3% by weight or less) using the electric conductivity, and from the relationship between the ammonia concentration and the electric conductivity described later. It is difficult to prepare a high concentration ammonia solution.

  FIG. 7 shows the relationship between the ammonia concentration of the ammonia solution and the electrical conductivity. In the figure, the horizontal axis represents the ammonia concentration (% by weight), the vertical axis represents the electric conductivity (μS / cm), the solid line represents the result at a liquid temperature of 25 ° C., and the broken line represents the result at a liquid temperature of 15 ° C. According to FIG. 7, the electrical conductivity of the ammonia solution once increases with an increase in ammonia concentration, but gradually decreases with an ammonia concentration of about 6% by weight as a boundary. Further, when the ammonia concentration is higher than 2% by weight, the electric conductivity varies depending on the temperature of the ammonia solution.

  As shown in FIG. 7, when the ammonia concentration is increased, the electric conductivity cannot be uniquely determined. Therefore, the upper limit of the concentration of the ammonia solution that can be adjusted by a conventional method using electrical conductivity is set to 3% by weight. As the ammonia to be injected into the system water, generally, the electric conductivity meter set value is 725 μS / m (72.5 mS / m), and the ammonia concentration is 1% by weight with little change in the electric conductivity due to the temperature of the ammonia solution. Solution is used.

  The present invention was made in view of such circumstances, and when controlling the quality of system water with ammonia alone without using hydrazine, while suppressing the remodeling content from the current boiler plant as much as possible, An object of the present invention is to provide a boiler plant capable of shortening the operation / storage switching time and an operation method thereof.

  In order to solve the above problems, the boiler plant and the operation method thereof according to the present invention employ the following means.

  The present invention includes a boiler that generates steam by heat from a heat source, a steam turbine that operates by the steam, a condenser that condenses exhaust gas from the steam turbine to condensate, and is condensed by the condenser. Ammonia is introduced into a system that sequentially connects the feed water pump that supplies the condensate to the boiler, an ammonia tank that contains an ammonia solution of a predetermined concentration, and the boiler, the steam turbine, the condenser, and the feed pump. In addition, a boiler plant including a pH increase promoting unit that increases the pH of the system water to a storage pH range of the boiler within a predetermined time is provided.

  The pH increase promoting unit includes an ammonia introducing unit that introduces the ammonia solution into the system, a detector that detects the amount of ammonia introduced into the system through the ammonia introducing unit, and a predetermined time in the system water. And a flow rate adjusting unit that adjusts the flow rate of the ammonia solution flowing through the ammonia introduction unit in accordance with the ammonia amount detected by the detector so that a predetermined amount of ammonia is introduced therein.

  The boiler plant may include a pH adjusting unit that adjusts the pH of the system water by supplying the ammonia solution via a pump in the system.

  1st aspect of the said invention WHEREIN: The said ammonia introduction part may be provided with the 1st conduit | pipe which connects the said ammonia tank and the inside of the vacuum vessel of the said condenser.

  2nd aspect of the said invention WHEREIN: The said ammonia introduction part may be provided with the 2nd conduit | pipe which connects the said ammonia tank and the inlet side piping of a condensate pump.

  3rd aspect of the said invention WHEREIN: The said ammonia introduction part is provided with the 3rd conduit | pipe which connects the said ammonia tank and the inlet side piping of the said water supply pump, The said pH raise promotion part is made into the said ammonia solution with instrument air. An instrument air inlet may be provided that is connected to the ammonia tank to apply pressure to push the ammonia solution into the third conduit.

  Both the vacuum container of the condenser and the inlet side piping of the condensate pump are in a reduced pressure environment, and there is a pressure difference with the ammonia tank. In the first aspect and the second aspect of the present invention, the ammonia solution can be led into the system without using a pump due to the pressure difference. Therefore, a large amount of ammonia can be reduced in the system regardless of the pump capacity. It is possible to lead to time. Moreover, in the 3rd aspect of this invention, an ammonia solution can be guide | induced into a system | strain without passing through a pump by pushing out an ammonia solution to a 3rd conduit | pipe using instrument air. According to the first to third aspects of the present invention, the pH of the system water can be raised to the storage pH range in a shorter time. The detector and the flow rate adjustment unit of the pH increase promotion unit can supply a predetermined amount of ammonia into the system.

  In the fourth aspect of the present invention, the pH increase promoting unit includes an ammonia rich tank that contains an ammonia rich solution having a predetermined ammonia concentration higher than that of the ammonia solution, and a rich that guides the ammonia rich solution into the system. An ammonia conduit.

  By using a high-concentration ammonia solution, the supply amount of ammonia can be increased without adding a pump, and the pH of the system water can be raised to the storage pH range of the boiler in a shorter time. A high concentration ammonia solution (ammonia rich solution) can be adjusted with an automatic hydrometer.

  5th aspect of this invention WHEREIN: The said pH raise promotion part connects either one of the vacuum vessel of the said condenser, or the inlet side piping of a condensate pump, and the waste_water | drain outlet of the said boiler, It is said the said condenser from the said boiler. A circulation path for circulating the system water to either one of a vacuum vessel of a water tank or an inlet side pipe of a condensate pump, and a filtration for filtering the system water provided in the middle of the circulation path, the pH increase promoting unit And a portion.

  According to the fifth aspect, by providing the circulation path, the pH of the system water can be increased to the storage pH range of the boiler even after the boiler is stopped and the temperature in the system is decreased. .

  The filtration unit can remove turbidity in the boiler wastewater. By removing the turbidity from the boiler wastewater and circulating it, damage to equipment such as pumps due to the turbidity can be prevented.

  The present invention also provides a boiler for generating steam by heat from a heat source, a steam turbine operated by the steam, a condenser for condensing exhaust gas from the steam turbine to condensate, and condensing by the condenser. A feed water pump that feeds the condensed water to the boiler, an ammonia tank that contains an ammonia solution of a predetermined concentration, and a system that sequentially connects the boiler, the steam turbine, the condenser, and the feed water pump are formed, PH adjusting unit for adjusting the pH of the system water by supplying the ammonia solution into the system, and a pH increase promoting unit for guiding the ammonia into the system to raise the pH of the system water to the storage pH range of the boiler And a method for operating a boiler plant comprising: introducing a predetermined amount of the ammonia into the system using the pH increase promoting unit; It provides a method for operating a boiler plant to increase the storage for the pH range of the boiler.

  In one aspect of the present invention, the system includes a pH adjusting unit that adjusts the pH of the system water by supplying the ammonia solution via a pump, and the ammonia solution is added to the system using the pH adjusting unit. It can be led into the system to raise the pH of the system water to the storage pH range of the boiler.

  In one aspect of the present invention, a predetermined amount of the ammonia is introduced into the system within a predetermined time due to a pressure reduction environment of the condenser or a pressure difference between an inlet side pipe of a condensate pump and the ammonia tank. Can be raised to the boiler storage pH range.

  Further, in one aspect of the present invention, instrument air is introduced into the ammonia tank during operation of the boiler, and a predetermined amount of the ammonia is supplied within a predetermined time by the pressure of the instrument air as needed. It may be led into the system to raise the pH of the system water to the storage pH range.

  In one aspect of the present invention, the pH increase promoting unit includes an ammonia rich tank that contains an ammonia rich solution having a predetermined ammonia concentration higher than that of the ammonia solution, and an automatic specific gravity that measures the specific gravity of the ammonia rich solution. And adjusting the ammonia-rich solution to a predetermined specific gravity range based on the measurement value of the automatic hydrometer, and introducing the ammonia-rich solution into the system within a predetermined time to adjust the pH of the system water in the boiler You may raise to the pH range for storage.

  Moreover, in one aspect of the present invention, the pH increase promoting unit is configured to connect the system water of the boiler that connects the discharge port of the system water of the boiler and a vacuum vessel of the condenser or an inlet side pipe of a condensate pump. The ammonia solution is supplied into the system by the pH adjusting unit, and the circuit is circulated by a pressure difference between the boiler and the inlet pipe of the condenser or the condensate pump. A circulating flow of the system water may be generated to raise the pH of the system water to a storage pH range.

  The boiler plant and its operation method according to the present invention, when managing the quality of the system water with ammonia alone without using hydrazine, suppresses the modification contents from the current boiler plant as much as possible, and reduces the operation / storage switching time. Can be shortened.

It is a principal part block diagram of the boiler plant which concerns on 1st Embodiment. It is a figure which shows the change of the ammonia concentration in elapsed time. It is a principal part block diagram of the boiler plant which concerns on 2nd Embodiment. It is a principal part block diagram of the boiler plant which concerns on 3rd Embodiment. It is a principal part block diagram of the boiler plant which concerns on 4th Embodiment. It is a principal part block diagram of the boiler plant which concerns on 5th Embodiment. It is a figure which shows the relationship between ammonia concentration and electrical conductivity.

  The present invention can be applied to a thermal power plant or a plant in which an exhaust heat recovery boiler (HRSG) is installed. Hereinafter, an embodiment of a boiler plant and an operation method thereof according to the present invention will be described with reference to the drawings.

[First Embodiment]
In FIG. 1, the principal part block diagram of the boiler plant 1 which concerns on this embodiment is shown. The boiler plant 1 includes a boiler 2, a steam turbine 3, a condenser 4, a feed water pump 5, a pH adjusting unit 21, and a pH increase promoting unit 22.

  The boiler 2, the steam turbine 3, the condenser 4 and the feed water pump 5 are sequentially connected to form a water circulation system. Hereinafter, this circulation system is referred to as “system”, and the water circulating through the circulation system is referred to as “system water”. The system water includes boiler water in the boiler 2, condensate condensed in the condenser 4, and feed water supplied to the boiler 2 by the feed water pump 5.

  The boiler 2 generates steam by heat from a heat source (not shown). The generated steam is exhausted to the condenser 4 after being used for work in the steam turbine 3. The exhausted steam (exhaust steam) is condensed in the condenser 4 to become condensate. Condensate is pumped out by a condensate pump 7. The condensate pumped out is guided to the boiler 2 by the feed water pump 5 as feed water.

  The boiler 2 includes an evaporator 8, a drum 9, and a economizer 10. In the boiler 2, the boiler water in the drum 9 is superheated and circulated in the evaporator 8 to generate steam. The exit side of the economizer 10 is connected to the drum 9. The economizer 10 can raise the temperature of the feed water and guide it to the drum 9.

  The condenser 4 includes a vacuum vessel (not shown), a cooling device (not shown), an air extraction device (not shown), and a condensate pump 7. The vacuum vessel is provided with an inlet opening and an outlet opening that serve as outlets and outlets for exhaust steam. The cooling device cools the exhaust steam passing through the vacuum vessel to generate condensate. The cooling device is, for example, a cooling pipe that circulates cooling water in the vacuum vessel and a cooling water circulation pump. The air bleeder can maintain a predetermined degree of vacuum inside the vacuum vessel. Examples of the air bleeder include an air bleeder and a vacuum pump. The predetermined degree of vacuum is, for example, an absolute pressure of about 730 mmHg to 710 mmHg. The condensate pump 7 is a pump that pumps the condensate from the condensate pool of the condenser 4. The type and structure of the condensate pump 7 can be determined by maintaining a high vacuum on the suction side.

  One end of a water supply line 11 (water supply system) is connected to the outlet side of the condensate pump 7. The economizer 10 is connected to the other end of the water supply line 11.

  The feed water pump 5 is provided in the middle of the feed water line 11 so as to feed the condensate pumped up by the condensate pump 7 to the economizer 10.

  The ammonia tank 20 contains a predetermined low concentration ammonia solution. In the present embodiment, the predetermined concentration of the low-concentration ammonia solution is 1% by weight to 3% by weight. The predetermined concentration of the low-concentration ammonia solution is based on the electrical conductivity or acid conductivity of the low-concentration ammonia solution (a method of measuring the electrical conductivity of the acid component by removing cation components such as mixed sodium ions). It may be converted.

  The pH adjusting unit 21 and the pH increase promoting unit 22 manage water quality of system water (particularly boiler water and feed water).

  The pH adjusting unit 21 is a facility that has been conventionally owned when managing the quality of system water being operated with ammonia. A predetermined low-concentration ammonia solution can be supplied from the ammonia tank 20 into the system to adjust the pH of the system water. The pH adjusting unit 21 includes an ammonia solution feeding path 23, a main feeding pump 24, and a sub feeding pump 25. The ammonia solution supply path 23 connects the bottom of the ammonia tank 20 and the water supply line 11 (upstream side of the water supply pump 5). The main feed pump 24 is installed in the middle of the ammonia solution feed path 23, and injects ammonia that is insufficient due to loss or the like into the operating boiler plant. The sub-feed pump 25 is installed in the middle of the ammonia solution feed path 23 in parallel with the main feed pump 24 and serves as a backup for the main feed pump 24.

  The pH increase promoting unit 22 has a larger amount of ammonia injected than the pH adjusting unit 21 and can increase the pH of the system water in a short time. The pH increase promoting unit 22 includes an ammonia introducing unit (first conduit) 26, a detector 27, and a flow rate adjusting unit 28. The first conduit 26 is a conduit having one end connected to the bottom of the ammonia tank 20 and the other end connected to the vacuum container of the condenser 4.

  The detector 27 detects the amount of ammonia guided to the system water through the first conduit 26. The detector 27 is, for example, a level switch or a level meter. The detector 27 in FIG. 1 is a level switch installed in the ammonia tank 20.

  The flow rate adjustment unit 28 is a flow rate adjustment valve that can adjust the flow rate of a predetermined low-concentration ammonia solution flowing in the first conduit 26. The level switch 27 and the flow rate adjusting valve 28 are electrically connected to a control device (not shown). The control device can control the opening degree of the flow rate adjusting valve 28 based on the signal output from the level switch 27.

  The control device includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program as an example, and the CPU reads the program into a RAM or the like to execute information processing / arithmetic processing. As a result, various functions are realized. The program is preinstalled in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Etc. may be applied. The computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

Next, the operation method of the boiler plant which concerns on this embodiment is demonstrated.
When the boiler 2 is normally operated, the quality of the system water is managed so that the system water maintains the operating pH range (pH 9.8 to 10.3).

  Specifically, at least one of the main feed pump 24 and the sub-feed pump 25 is operated to feed a predetermined low concentration ammonia solution to the system water via the ammonia solution feed path 23. The feed amount of the predetermined low-concentration ammonia solution corresponds to the ammonia solution amount to which the ammonia amount necessary to compensate for the plant loss (loss, etc.) in the system is added.

  When the boiler 2 is stored for several days, for example, due to shutdown, the pH of the system water is in the storage pH range (pH 9.8 to 10.3), and preferably the system water during operation of the boiler 2 The quality of the system water is controlled to be higher than the pH of the water.

  Specifically, during normal operation of the boiler 2, the opening degree of the flow rate adjustment valve 28 is adjusted by a control device (not shown), and a predetermined low-concentration ammonia solution is introduced into the system (S1). At this time, the main feed pump 24 (and the sub feed pump 25) may be stopped. By utilizing the pressure difference between the vacuum tanks of the ammonia tank 20 and the condenser 4, a large amount of a predetermined low-concentration ammonia solution can be introduced into the system in a shorter time than the pH adjuster 21. The predetermined low-concentration ammonia solution introduced into the vacuum vessel is diffused into the system by circulation of the system water.

  The level switch 27 is set so as to detect the amount of ammonia (predetermined amount of ammonia) necessary to raise the pH of the system water from the operating pH to the storage pH. The necessary ammonia amount may be calculated in advance and converted into a predetermined low concentration ammonia solution amount. When a predetermined amount of ammonia is introduced into the system water, the level switch outputs the information to the control device. The control device closes the flow rate adjusting valve 28 based on the information. This can prevent an excessive amount of ammonia from being introduced into the system. As a result, immediately after a predetermined amount of ammonia is introduced to the system water, even if there is a portion where the ammonia concentration is uneven in the system water temporarily, it is ensured that the necessary pH is maintained while the system water is circulating. Since the value (ammonia concentration) can be adjusted, management becomes easy.

  The speed at which a predetermined low-concentration ammonia solution is introduced into the system can be controlled by the degree of vacuum in the vacuum vessel and the opening of the flow rate adjustment valve 28. For example, the speed at which a predetermined low-concentration ammonia solution is introduced into the system is a predetermined amount within a predetermined time which is the time required for the system water to make a round in the system (0.5 h according to equation (6) described later). To control all ammonia in the system (in the vacuum vessel).

In the present embodiment, after increasing the pH of the system water in a short time by the pH increase promoting unit 22, the pH of the system water may be finely adjusted by the pH adjusting unit 21 (S2). In that case, the injection amount of the predetermined low-concentration ammonia solution through the first conduit is set so that 80% to 95% of the predetermined amount of ammonia can be injected. As a result, the time required to increase the storage pH in S2 is 0.2 h to 0.5 h, but it is sufficiently short compared to 3.5 h according to the above formula (5), and ammonia. Can be accurately controlled.
Also in this case, the amount of the predetermined low-concentration ammonia solution injected from the pH adjusting unit 21 is detected by the level switch 27, and an appropriate injection amount can be managed.

  After adjusting the pH of the system water within the storage pH range, the operation of the boiler 2 is stopped.

Next, specific examples relating to the present embodiment will be described below.
In a boiler plant with a boiler water volume of, for example, 200 ton and a feed water pump capacity of, for example, 400 ton / h,
It takes 0.5h for the system water to make a round in the system.
(Retained water volume: 200 ton / feed water pump capacity: 400 ton / h) (6)
It is.

When the pH of the system water is 9.8 (amount of ammonia per unit volume of 5 mg / L), the amount of ammonia in the system is 1,000 g. When the pH of the system water is 10 (amount of ammonia per unit volume 12 mg / L), the amount of ammonia in the system is 2,400 g. Therefore, the pH can be raised to 10 by adding 1,400 g of ammonia to the system water having a pH of 9.8 according to the above-described equation (4).
To raise the pH of the system water from 9.8 to 10,
When the necessary amount of ammonia 1,400 g is converted into a 1 wt% ammonia solution amount, 140 is obtained.
L (ammonia amount: 1,400 g / concentration: 1% / 1000) (7)
It becomes.

  When a 1 wt% ammonia solution is stored in the ammonia tank 20, the level switch 27 may be set so that it can be detected that the amount of the 1 wt% ammonia solution in the ammonia tank 20 has decreased by 140 L.

  When the vacuum degree of the condenser 4 is 720 mmHg, it is sufficiently possible to introduce 140 L of 1 wt% ammonia solution according to the equation (7) into the vacuum vessel in 0.5 h according to the above equation (6). is there.

  FIG. 2 shows changes in the ammonia concentration of the system water over time. In the figure, the horizontal axis is the elapsed time (h), the vertical axis is the ammonia amount per unit volume of the system water (mg / L), and the thick line is the water quality of the system water managed by the operation method of this embodiment. This is a case where the water quality of the system water is managed only by the pH adjusting unit (two units of the main feed pump 24 and the sub feed pump 25). As shown in FIG. 2, by using the pH increase promoting unit 22, the pH of the system water is increased from 9.8 to 10 compared to when the system water quality is controlled only by the pH adjusting unit 21. The time required can be greatly reduced.

  Further, 80% to 95% of a predetermined amount of ammonia is injected by the pH increase promoting unit 22 as S1, and then 20% to 5% of the remaining predetermined amount of ammonia is injected by the pH adjusting unit 21 as S2. As a result, the time required to increase the storage pH of the boiler at S2 is 0.2 h to 0.5 h, but it is necessary to increase the pH of the system water from 9.8 to 10. While maintaining the effect that the time can be shortened to the same extent, the accuracy of ammonia injection can be managed high, and the excess or deficiency of the ammonia injection amount can be suppressed.

  According to this embodiment, since the quality of the system water is managed by ammonia alone without using hydrazine, the system water replacement operation can be omitted during storage and restart. Moreover, since the operation of the boiler 2 can be resumed without discarding the water in the system, the restart time is shortened.

  According to this embodiment, since the reduced pressure environment of the condenser 4 is used as a means for feeding a predetermined low-concentration ammonia solution, there is no need to update or add to a large-capacity pump. Compared with the case where it is used, the time taken to increase the pH of the system water from 9.8 to 10 can be shortened.

[Second Embodiment]
In FIG. 3, the principal part block diagram of the boiler plant 30 which concerns on this embodiment is shown. The boiler plant 30 according to the present embodiment is different from the first embodiment in the pH increase promotion unit 32. The description of the same configuration as in the first embodiment is omitted.

  In the present embodiment, the pH increase promoting unit 32 includes an ammonia introducing unit (second conduit) 36, a detector 27, and a flow rate adjusting unit 28.

  The second conduit 36 is a conduit having one end connected to the bottom of the ammonia tank 20 and the other end connected to the inlet side piping 33 of the condensate pump 7.

  The inlet-side piping 33 of the condensate pump 7 has the same submersible pressure as the exhaust steam is cooled and accumulated as condensate by a cooling device (not shown) in the condenser 4, but is the same as the vacuum vessel. In a reduced pressure environment. Therefore, the pH increase promotion part 32 has the same effect as the pH increase promotion part 22 of the first embodiment. In addition, the ammonia injected from the pH increase promotion unit 32 is preferably mixed with the condensate and introduced into the system water, which facilitates the homogenization of the ammonia concentration in the system water.

[Third Embodiment]
In FIG. 4, the principal part block diagram of the boiler plant 40 which concerns on this embodiment is shown. The boiler plant 40 according to the present embodiment is different from the first embodiment in the pH increase promoting unit 42. The description of the same configuration as in the first embodiment is omitted.

  In the present embodiment, the pH increase promotion unit 42 includes an instrument air introduction unit 43, an ammonia introduction unit (third conduit) 46, a detector 27, and a flow rate adjustment unit 28.

The instrument air introduction unit 43 has one end connected to an instrument air supply source (not shown) and the other end connected to the vertical upper part of the ammonia tank 20. The instrument air supply source may be any one that can supply instrument air into the ammonia tank 20 at a pressure of 10 to 20 kg / cm ² . The instrument air supply source is, for example, one that is stored in an air receiver by dehumidifying and deoiling air compressed by an air compressor (not shown). The ammonia tank 20 has a sealing property that prevents the introduced instrument air from leaking out.

  The third conduit 46 is a conduit having one end connected to the bottom of the ammonia tank 20 and the other end connected to the water supply line 11 between the condensate pump 7 and the water supply pump 5.

  When the boiler 2 is stored, instrument air is introduced into the ammonia tank 20 while the boiler 2 is in operation, and the flow rate adjustment valve 28 is opened to introduce a predetermined low concentration ammonia solution into the system. By introducing the instrument air, pressure is applied to a predetermined low concentration ammonia solution, and the predetermined low concentration ammonia solution is pushed out to the third conduit 46. The opening degree of the flow rate adjusting valve 28 is such that the supply of a predetermined amount of a predetermined low-concentration ammonia solution is completed within a predetermined time required for one cycle of the system water (for example, 0.5 h according to the above equation (6)). To do.

  According to the present embodiment, by using instrument air, a large amount of a predetermined low-concentration ammonia solution is introduced into the system in a shorter time than when the water quality is managed only by the pH adjusting unit 21 that is a conventionally owned facility. Can lead to. The predetermined low-concentration ammonia solution introduced into the system is diffused into the system by circulation of the system water.

  After supplying a predetermined amount of a predetermined low-concentration ammonia solution, the introduction of instrumentation air is terminated. The ammonia tank 20 is returned to atmospheric pressure by an open valve (not shown), and a predetermined low-concentration ammonia solution is generated and stored in the ammonia tank 20 in preparation for the next ammonia solution supply opportunity.

[Fourth Embodiment]
In FIG. 5, the principal part block diagram of the boiler plant 50 which concerns on this embodiment is shown. The boiler plant 50 is different from the first embodiment in the pH increase promoting unit. The description of the same configuration as in the first embodiment is omitted.

  In the ammonia tank 20 of FIG. 5, an electrical conductivity meter 20 a that measures the electrical conductivity of a predetermined low-concentration ammonia solution accommodated in the ammonia tank 20, and a first gas that supplies ammonia gas into the ammonia tank 20 A first stirring unit 20c that stirs the solution stored in the supply unit 20b and the ammonia tank 20 is installed. Ammonia gas can be derived from a gas source for the denitration apparatus. This structure may be used to generate a predetermined low-concentration ammonia solution in the ammonia tank 20 of the first to third embodiments described above.

  In addition to the ammonia tank 20, the pH increase promoting unit 52 further includes an ammonia rich tank 53, a rich ammonia conduit 56, and a switching valve 58.

  The ammonia rich tank 53 stores a predetermined high concentration ammonia rich solution having a higher ammonia concentration than a predetermined low concentration ammonia solution (for example, 1% by weight). The predetermined high concentration of the ammonia-rich solution includes, for example, 7 wt% to 25 wt% ammonia.

  The ammonia rich tank 53 includes an automatic hydrometer 54 that measures the specific gravity of the solution stored in the ammonia rich tank 53, a second gas supply unit 55 that supplies ammonia gas into the ammonia rich tank 53, and an ammonia rich tank 53. The 2nd stirring part 57 which stirs the solution accommodated in is installed. Ammonia gas can be derived from a gas source for the denitration apparatus.

  The rich ammonia conduit 56 is a conduit for introducing an ammonia rich solution to the system water. The rich ammonia conduit 56 has one end connected to the bottom of the ammonia rich tank 53 and the other end connected to the ammonia solution feeding path 23.

  The switching valve 58 is provided at a connection portion between the ammonia solution supply path 23 and the rich ammonia conduit 56. The switching valve 58 is electrically connected to a control device (not shown). The control device can switch between the supply of the predetermined low-concentration ammonia solution and the supply of the ammonia-rich solution so that a predetermined amount of ammonia is guided to the system water when the boiler 2 is stored.

  In the present embodiment, the predetermined low-concentration ammonia solution is adjusted by the electric conductivity meter 20a. Specifically, after injecting pure water into the ammonia tank 20, ammonia gas is supplied into the tank by the first gas supply unit 20b and stirred by the first stirring unit 20c. The electric conductivity of the solution in the ammonia tank 20 is measured by the electric conductivity meter 20a and adjusted to a predetermined low concentration ammonia solution (for example, 1% by weight).

  The ammonia rich solution is adjusted by an automatic hydrometer 54. As described above, since the ammonia concentration in the ammonia rich tank 53 is high, the electric conductivity meter 20a cannot be used. Since the electric conductivity meter 20a is suitable for measurement at an ammonia concentration of 1% by weight to 3% by weight or less, the automatic hydrometer 54 can measure and manage a high concentration of ammonia. Specifically, after injecting pure water into the ammonia rich tank 53, ammonia gas is supplied into the tank by the second gas supply unit 55 and stirred by the second stirring unit 57. The specific gravity of the solution in the ammonia rich tank 53 is measured by the automatic hydrometer 54 and adjusted to a predetermined ammonia rich solution (for example, 25% by weight). The specific gravity of the ammonia-rich solution measured by the automatic hydrometer 54 is, for example, 0.909 g / mL at 25% by weight of ammonia.

  When the boiler 2 is stored, the flow path is switched by the switching valve 58 so that the rich ammonia conduit 56 side is opened while the boiler 2 is in operation, and a predetermined amount of ammonia-rich solution is introduced into the system within a predetermined time. .

  After increasing the pH of the system water in a short time by the pH increase promoting unit 52, the pH of the system water may be finely adjusted by the pH adjusting unit 21 as in the first embodiment.

For example, the amount of ammonia required to increase the pH of the system water from 9.8 to 10 is 1,400 g, and the capacities of the main feed pump 24 and the sub feed pump 25 are each 20 L / h. The water quality of the system water is controlled using a 25 wt% ammonia-rich solution.
in this case,
The shortest time required to supply the ammonia-rich solution is about 8.4 minutes (ammonia amount: 1.4 kg / (pump: 20 L / h × 2 units × concentration: 25%) = 0.14 h)
It is.

When the predetermined time required for the system water to make a round in the system is 0.5 h as in the above-described equation (6), and when the supply of the ammonia rich solution is completed accordingly,
Necessary pump injection rate is 11.2L / h
(Ammonia amount: 1.4 kg ÷ (one round time: 0.5 h × concentration 25%))
Therefore, the main feed pump 24 and the sub feed pump 25 may be operated at a load of about 56%.
Or, if the main feed pump 24 and the sub-feed pump 25 are operated at the maximum load,
Concentration of ammonia-rich solution is about 7% (concentration: 25% x flow rate: 11.2 L / h ÷ (pump: 20 L / h x 2 units))
Then, the supply of the ammonia-rich solution can be completed while the system water makes a circuit in the system.

Therefore, the concentration of the ammonia-rich solution in the present embodiment can be 7 wt% to 25 wt% according to the loads of the main feed pump 24 and the sub feed pump 25. Steps similar to S1 and S2 shown in FIG. 2 are divided, and 80% to 95% of a predetermined amount of the ammonia-rich solution is injected as S1 from the ammonia-rich tank 53 through the rich ammonia conduit 56, and then the remaining predetermined amount 20% to 5% is injected from the ammonia tank 20 as S2 by a predetermined low concentration ammonia solution. As a result, the amount of time required to increase the storage pH to S2 in S2 is slightly added, but the time required to increase the pH of the system water from 9.8 to 10 is substantially increased. While maintaining the effect of shortening, it is possible to manage the accuracy of ammonia injection highly and to suppress the excess or deficiency of the ammonia injection amount.
In the ammonia tank 20 and the ammonia rich tank 53, a detector (level switch) 27 may be used.

  According to this embodiment, since a high concentration ammonia solution having a predetermined high concentration can be adjusted, a large amount of ammonia can be introduced into the system in a short time by an existing ammonia feed pump.

[Fifth Embodiment]
In FIG. 6, the principal part block diagram of the boiler plant 60 which concerns on this embodiment is shown. The boiler plant 60 is different from the first embodiment in the pH increase promoting unit 62. The description of the same configuration as in the first embodiment is omitted.

  According to the present embodiment, when it becomes necessary to store the boiler plant 60 after the operation of the boiler 2 is stopped, the system water is not replaced with the system water for operation and the storage system water is stored. The pH of the water can be raised to the storage pH range.

  The pH increase promotion unit 62 includes a circulation path 66 that connects either the vacuum container of the condenser 4 or the inlet side piping 33 of the condensate pump 7 and the drain outlet of the boiler 2 (evaporator 8). 66, and a filtration unit 67 provided in the middle. Open / close valves 63 and 64 are respectively provided at the entrance and exit of the circulation path 66.

  The filtration unit 67 removes turbid components (scale and sludge) from the boiler water (system water) discharged from the evaporator 8 in order to suppress damage to the pump and the like. The suspended matter is mainly iron oxide.

  In the first to fifth embodiments, it is necessary to inject the ammonia solution into the system water while the boiler plant is in operation. In the present embodiment, even after the boiler 2 is stopped, at least one of the main feed pump 24 and the sub feed pump 25 is operated to feed the ammonia solution into the system, and the open / close valve 63. , 64 are opened. Thereby, ammonia can be diffused in the system (in FIG. 6, the water supply system from the inlet side pipe 33 of the condensate pump 7 to the boiler 2), and the pH of the system water can be raised to the storage pH range.

  In addition, 1st Embodiment-3rd Embodiment can be combined, respectively.

1, 30, 40, 50, 60 Boiler plant 2 Boiler 3 Steam turbine 4 Condenser 5 Condensate pump 7 Condensate pump 8 Evaporator 9 Drum 10 Conservator 11 Feed water line 20 Ammonia tank 20a Electric conductivity meter 20b First Gas supply part 20c 1st stirring part 21 pH adjustment part 22,32,42,52,62 pH increase promotion part 23 Ammonia solution feed path 24 Main feed pump 25 Sub feed pump 26 Ammonia introduction part (first conduit)
27 Level switch (detector)
28 Flow rate adjustment valve (Flow rate adjustment part)
33 Condensate pump inlet side piping 36 Ammonia introduction part (second conduit)
43 Instrument air introduction part 46 Ammonia introduction part (third conduit)
53 Ammonia Rich Tank 54 Automatic Hydrometer 55 Second Gas Supply Unit 56 Rich Ammonia Conduit 57 Second Stirring Unit 58 Switching Valve 63, 64 Open / Close Valve 66 Circulation Path 67 Filtration Unit

Claims (15)

A boiler that generates steam by heat from a heat source;
A steam turbine operated by the steam;
A condenser for condensing the exhaust of the steam turbine to condensate;
A water supply pump for feeding the condensate condensed in the condenser to the boiler;
An ammonia tank containing an ammonia solution of a predetermined concentration;
A pH increase promoting unit that introduces ammonia into a system that sequentially connects the boiler, the steam turbine, the condenser, and the feed water pump, and raises the pH of the system water to a storage pH range of the boiler within a predetermined time; ,
Boiler plant equipped with. The pH increase promoting part is
An ammonia introduction part for guiding the ammonia solution into the system;
A detector for detecting the amount of ammonia introduced into the system via the ammonia introduction part;
A flow rate adjusting unit that adjusts the flow rate of the ammonia solution flowing through the ammonia introduction unit according to the amount of ammonia detected by the detector so that a predetermined amount of ammonia is guided to the system water within a predetermined time;
A boiler plant according to claim 1.   The boiler plant of Claim 2 provided with the pH adjustment part which supplies the said ammonia solution via a pump and adjusts the pH of the said system water in the said system | strain.   4. The boiler plant according to claim 2, wherein the ammonia introduction unit includes a first conduit that connects the ammonia tank and a vacuum container of the condenser.   The boiler plant in any one of Claims 2-4 with which the said ammonia introduction part is provided with the 2nd conduit | pipe which connects the said ammonia tank and the inlet side piping of a condensate pump. The ammonia introduction part includes a third conduit connecting the ammonia tank and an inlet side pipe of the water supply pump;
The said pH rise promotion part is equipped with the instrumentation air introduction part connected to the said ammonia tank so that the said ammonia solution may be pressurized with instrumentation air, and the said ammonia solution may be pushed out to the said 3rd conduit | pipe. The boiler plant according to any one of 5. The pH increase promoting part is
An ammonia rich tank containing an ammonia rich solution having a predetermined ammonia concentration higher than the ammonia solution;
A rich ammonia conduit for directing the ammonia rich solution into the system;
A boiler plant according to claim 1.   The boiler plant according to claim 7, wherein the pH increase promoting unit includes an automatic hydrometer that measures the specific gravity of the ammonia-rich solution stored in the ammonia-rich tank. The pH increase promoting unit connects either the vacuum container of the condenser or the inlet side piping of the condensate pump and the drain outlet of the boiler to connect the vacuum container of the condenser or the condensate pump from the boiler. A circulation path for circulating the system water to any one of the inlet side pipes of
The pH increase promoting unit is provided in the middle of the circulation path and filters the system water;
The boiler plant in any one of Claims 1-8 provided with these. A boiler that generates steam by heat from a heat source;
A steam turbine operated by the steam;
A condenser for condensing the exhaust of the steam turbine to condensate;
A water supply pump for feeding the condensate condensed in the condenser to the boiler;
An ammonia tank containing an ammonia solution of a predetermined concentration;
A pH increase promoting unit that introduces ammonia into a system that sequentially connects the boiler, the steam turbine, the condenser, and the feed water pump to increase the pH of the system water to a storage pH range of the boiler;
A boiler plant operation method comprising:
A method for operating a boiler plant, wherein the ammonia is introduced into the system using the pH increase promoting unit, and the pH of the system water is increased to a storage pH range of the boiler within a predetermined time. In the system, provided with a pH adjusting unit for adjusting the pH of the system water by supplying the ammonia solution via a pump,
The boiler plant operation method according to claim 10, wherein the ammonia solution is introduced into the system using the pH adjusting unit to raise the pH of the system water to a storage pH range of the boiler.   Due to the reduced pressure environment of the condenser or the pressure difference between the inlet side pipe of the condensate pump and the ammonia tank, a predetermined amount of the ammonia is introduced into the system within a predetermined time, and the pH of the system water is set in the boiler. The operation method of the boiler plant of Claim 10 or Claim 11 raised to the pH range for storage.   During operation of the boiler, instrument air is introduced into the ammonia tank, and a predetermined amount of the ammonia is introduced into the system as needed within a predetermined time by the pressure of the instrument air. The operation method of the boiler plant in any one of Claims 10-12 which raises pH of water to the pH range for storage.   The pH increase promoting unit includes an ammonia-rich tank that contains an ammonia-rich solution having a predetermined ammonia concentration higher than that of the ammonia solution, and an automatic hydrometer that measures the specific gravity of the ammonia-rich solution, and the automatic hydrometer The ammonia-rich solution is adjusted to a predetermined specific gravity range based on the measured value, and the ammonia-rich solution is led into the system within a predetermined time to raise the pH of the system water to the storage pH range of the boiler. The operation method of the boiler plant of Claim 10 or Claim 11. The pH increase promoting unit includes a circulation path for circulating the system water of the boiler that connects a discharge port of the system water of the boiler and a vacuum vessel of the condenser or an inlet side pipe of a condensate pump,
The pH adjusting unit supplies the ammonia solution into the system, and generates a circulation flow of the system water in the circulation path due to a pressure difference between the boiler and an inlet side pipe of the condenser or the condensate pump. The operation method of the boiler plant of Claim 11 which raises pH of the said system | strain water to the pH range for storage.

Images