Method and apparatus for treating condenser extract gas

Abstract

To provide a method and a device for treating a condenser extraction gas that can efficiently recover ammonia from a noncondensing gas from a condenser.SOLUTION: A method for treating a condenser extraction gas includes the steps of: cooling a noncondensing gas extracted from a condenser 5 with a first heat exchanger 10 to separate condensed water from the gas; bringing the separated gas into contact with water with a line mixer 32 and a scrubber 40 to dissolve a water-soluble component into the water; and merging condensed water from the first heat exchanger 10 and outflow water from the scrubber 40 with condensed water.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and apparatus for treating extracted gas from a condenser of a power plant such as a thermal power plant or a nuclear power plant. One aspect of the present invention relates to a method and apparatus for recovering ammonia from the extracted gas.

Background Art

[0002] In steam power plants such as thermal power plants and nuclear power plants, exhaust steam from a steam turbine is cooled and condensed into condensed water in a condenser. If non-condensable gas remains and accumulates in the condenser, it causes a decrease in vacuum degree and deterioration of heat transfer performance. Therefore, the non-condensable gas is continuously extracted from the condenser by an air ejector using a steam ejector or a vacuum pump (Patent Document 1).

[0003] In power generation boilers, ammonia is added to increase the pH of feed water and condensed water (Patent Document 2, etc.).

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problem to be Solved by the Invention

[0005] [Problem 1] Ammonia has extremely high volatility and is discharged out of the system through exhaust from the air extractor in addition to boiler blow and deaerator vent steam, so it is necessary to replenish the steam cycle such as feed water with the same amount of ammonia as the discharged ammonia amount.

[0006] If a large amount of ammonia needs to be replenished, the amount of ammonia to be stored will also increase. Chemical solutions with an ammonia concentration exceeding 1% require careful handling, and notification and containment dikes may be necessary. Preparing dilute ammonia solutions has disadvantages, such as requiring larger storage tanks and thus higher initial costs.

[0007] One aspect of the present invention aims to provide a method and apparatus for processing condenser extract gas that can efficiently recover ammonia from exhaust gas containing ammonia from an air extractor.

[0008] [Challenge 2] Steam from boilers contains low-molecular-weight volatile organic compounds (VOCs: Volatile Organic Carbon, including low-molecular-weight organic acids) and carbon dioxide, which are produced by the thermal decomposition of organic matter introduced from the makeup water. Therefore, when ammonia is dissolved in condensate using an air extractor, these are also recovered simultaneously, making it difficult to release VOCs and carbon dioxide from the steam cycle. As a result, the acidic electrical conductivity of feedwater, steam, and condensate may increase. When acidic electrical conductivity increases, it becomes difficult to monitor the inclusion of impurities in the boiler water system based on electrical conductivity.

[0009] Another aspect of the present invention aims to provide a method and apparatus for treating condenser extract gas that can remove carbon dioxide and organic acids from exhaust gas and condensed water from an air extractor. [Means for solving the problem]

[0010] The gist of this invention is as follows:

[0011] [1] A first step involves cooling the non-condensable gas extracted from the condenser in a first heat exchanger to separate it into condensate and gas, A second step involves bringing the separated gas into contact with gas absorption water consisting of condensate or pure water in a gas absorption device, thereby dissolving the water-soluble components in the gas in the water. The third step involves combining the water-soluble component-dissolved water from the second step with the boiler condensate. A method for processing condenser extract gas having the following characteristics.

[0012] [2] A method for treating condenser extract gas according to [1], further comprising the step of passing the water-soluble component dissolved water from the second step through an OH-type ion exchange apparatus.

[0013] [3] A method for treating condenser extract gas according to [2], wherein the water containing water-soluble components from the second step is cooled in a second heat exchanger, and then passed through the OH-type ion exchange apparatus.

[0014] [4] The second heat exchanger is used to cool the water-soluble component dissolved in

[0015] [5] The gas absorption device is at least one of a line mixer and a scrubber, a method for treating condenser extracted gases according to any of [1] to [4].

[0016] [6] A method for treating condenser extract gas according to [1], wherein the condensate from the first heat exchanger is passed through an OH-type ion exchanger and then combined with the boiler condensate.

[0017] [7] A gas-liquid separation step in which the non-condensable gas extracted from the condenser is cooled in a first heat exchanger to separate it into condensed water and gas, This condensed water is treated by passing it through an OH-type ion exchange device in an ion exchange treatment process, The process involves combining the water treated by the ion exchange device with the boiler condensate. A method for processing condenser extract gas having the following characteristics.

[0018] [8] A first heat exchanger that cools the non-condensable gas extracted from the condenser to separate it into condensate and gas, A gas absorption device that brings the gas separated in the first heat exchanger into contact with gas absorption water consisting of condensate or pure water, and dissolves the water-soluble components in the gas in the water, A means for combining the water-soluble component-dissolved water from the gas absorption device with the boiler condensate. An apparatus for treating gas extracted from a condenser, comprising:

[0019] [9] A first heat exchanger that cools non-condensable gas extracted from a condenser to separate the gas into condensed water and a gas; An OH-type ion exchange device through which condensed water from the first heat exchanger is passed; means for combining the water treated by said ion exchange device with boiler condensate; and An apparatus for treating gas extracted from a condenser, comprising same. Effects of the Invention

[0020] According to one aspect of the present invention, ammonia can be efficiently recovered from non-condensable gas from a condenser.

[0021] According to another aspect of the present invention, carbon dioxide and organic acids can be efficiently removed from non-condensable gas from a condenser and condensed water thereof. By efficiently removing organic acids and carbonic acid from non-condensable gas, the acid electrical conductivity of boiler water and the condenser can be reduced. Brief Description of the Drawings

[0022] [Figure 1] It is a system diagram of a boiler water system showing a first embodiment. [Figure 2] It is a system diagram of a boiler water system showing a second embodiment. [Figure 3] It is a system diagram of a boiler water system showing a third embodiment. [Figure 4] It is a system diagram of a boiler water system showing a fourth embodiment. Mode for Carrying Out the Invention

[0023] Embodiments are described below with reference to FIGS. 1 to 4.

[0024] FIG. 1 is a system diagram of a boiler water system for explaining a method and apparatus for treating condenser extracted gas according to an embodiment of the first aspect.

[0025] The steam generated in boiler 1 is sent to steam turbine 3 via line 2, which consists of pipes, and electricity is generated by generator 4.

[0026] The turbine exhaust is condensed into condensate by the condenser 5. The condenser 5 is equipped with numerous cooling pipes 6. Cooling water, such as river water or seawater, is passed through the cooling pipes 6.

[0027] Condensate is introduced from the condenser 5 to the first heat exchanger 10 via the condensate pump 7 and line 8. This heat exchanger 10 is for cooling the extracted gas, which will be described later. The condensate from line 8 flows from the inlet header 11 through the cooling pipe 12 to the outlet header 13 and out to line 14.

[0028] The condensate is sent from line 14 through line 15, through the deaerator 16, and then through line 17, feedwater pump 18, and line 19 to boiler 1.

[0029] Although not shown in the diagram, a water supply tank may be provided in line 15, and makeup water may be supplied to this water supply tank. In addition, an aqueous ammonia solution is added to the water supply tank or to line 15 thereafter by an additive device (not shown) so that the pH of the water supply is within a predetermined range.

[0030] Non-condensable gas is extracted from the top of the condenser 5 by line 21 and ejector 22. Water vapor is supplied to ejector 22 as a working fluid by line 23. The mixed gas of non-condensable gas and water vapor from ejector 22 is introduced into the cooled fluid chamber 25 of the heat exchanger 10 via line 24, where it is cooled by the cooling pipe 12 to become condensed water. This condensed water is sent to line 15 via line 26.

[0031] A considerable amount of ammonia from the non-condensable gas is dissolved in this condensed water.

[0032] Non-condensable gases that did not dissolve in the condensed water in the cooled fluid chamber 25 of the heat exchanger 10 are introduced into the line mixer 32 via the extraction line 31. Water is introduced into the line mixer 32 from the bottom of the scrubber 40 (described later) via the pump 33 and line 34. The water and gas are mixed in the line mixer 32, and most of the soluble gas components, including ammonia, that did not dissolve in the cooled fluid chamber 25 dissolve in the water. The gas-liquid mixed fluid flowing out of the line mixer 32 is introduced into the lower part of the scrubber 40 via line 35.

[0033] The scrubber 40 includes a tower-shaped casing 41, a packing layer 42 provided horizontally across the casing 41 near the middle section, a mist removal layer 43 provided above the packing layer 42, a sprinkler 44 positioned between the packing layer 42 and the mist removal layer 43, a line 46 for supplying water from the bottom of the casing 41 to the sprinkler 44 via a pump 45, an exhaust line 47 connected to the top of the casing 41, a line 48 for supplying condensate or pure water to the top of the casing 41, and an outlet 49 for discharging water from the bottom of the casing 41.

[0034] A gas-liquid mixed fluid from line 35 is introduced to the underside of the packing layer 42. Of the introduced fluid, the gaseous component rises within the casing 41. Water supplied from line 48 and water sprayed from sprinkler 44 pass through the packing layer 42 and fall to the bottom of the casing 41. During this time, they come into contact with the gas rising within the casing 41, and soluble components such as ammonia in the gas dissolve into the water and accumulate at the bottom of the casing 41. The gas from which the soluble components have been removed is discharged through exhaust line 47. Some organic acids and carbon dioxide do not dissolve in water and are discharged along with the gas.

[0035] A portion of the water accumulated at the bottom of the casing 41 is sent to the line mixer 32 via the pump 33 and the line 34. Another portion of the water accumulated in the casing 41 is sent to the sprinkler 44 via the pump 45 and the line 46 for sprinkling.

[0036] A portion of the water at the bottom of the casing 41, where the soluble components have dissolved, is sent from the outlet 49 to the deaerator 16 via line 51 and line 15 to which line 51 is connected. In this embodiment, line 51 and line 26 merge and connect to line 15, but lines 26 and 51 may also be connected to line 15 individually.

[0037] Thus, in this embodiment, the non-condensable gas from the first heat exchanger 10 is passed through the line mixer 32 and scrubber 40, and the soluble components are dissolved in water, so that most of the ammonia in the non-condensable gas is efficiently dissolved in water and recovered. In addition, the ammonia concentration in the exhaust from the scrubber 40 is sufficiently low. Furthermore, by removing organic acids and carbonic acid from the non-condensable gas, the acidic electrical conductivity of the boiler feedwater and condensate can be reduced.

[0038] Furthermore, the amount of water flowing to the line mixer 32 and the amount of water sprayed by the scrubber 40 may be controlled according to the exhaust volume from the condenser 5.

[0039] In Figure 1, the line mixer 32 and scrubber 40 are installed in series to dissolve soluble components in the non-condensable gas in water using the line mixer 32 and scrubber 40. However, the line mixer 32 may be installed alone, or the scrubber 40 may be installed alone.

[0040] If only the line mixer 32 is installed, the gas-liquid mixed fluid from line 35 is introduced into the gas-liquid separator 60 for gas-liquid separation, as shown in Figure 2 below.

[0041] If only the scrubber 40 is installed, although not shown in the diagram, gas from line 31 is introduced into the scrubber 40.

[0042] Figure 2 shows an example in which the scrubber 40 is omitted and the soluble components are dissolved in water using only the line mixer 32. The gas-liquid mixed fluid flowing out of the line mixer 32 is introduced to the gas-liquid separator 60 through line 35, where gas-liquid separation treatment is performed. The separated gas components are discharged through line 61. A portion of the water in the gas-liquid separator 60 is supplied to the line mixer 32 via pump 33 and line 34.

[0043] A portion of the water containing dissolved soluble components in the gas-liquid separator 60 is cooled through line 62 to the second heat exchanger 63, and then sent via line 64 to the OH-type ion exchanger 65, where it is used to separate organic acids and carbonate components from the OH-type ion exchanger. - After undergoing ion exchange treatment to become high-pH ammonia-containing water, it is sent to the deaerator 16 via lines 66 and 15.

[0044] Condensate or pure water is circulated as the low-temperature fluid in the heat exchanger 63 to cool the water containing soluble components from the gas-liquid separator 60. The condensate or pure water that flows out of the heat exchanger 63 is sent to the inlet side (or line 34) of the line mixer 32 via line 67. The reason for cooling the water containing soluble components in the heat exchanger 63 is to protect the ion exchange resin of the ion exchange device 65 (keeping it below the durability temperature of the ion exchange resin).

[0045] The other components of Figure 2 are the same as those in Figure 1, and the same part numbers indicate the same parts.

[0046] Figure 3 shows an embodiment of Figure 1 in which an OH-type ion exchange device 65 is installed in a portion of line 51 (downstream of the confluence with line 26 and upstream of the confluence with line 14) 51A. The water containing soluble components that flows out of the scrubber 40 into line 51 passes through the OH-type ion exchange device 65, removing organic acids and carbonic acid, and becoming a high-pH ammonia solution before flowing into line 15.

[0047] The other components of Figure 3 are the same as those in Figure 1, and the same part numbers indicate the same parts.

[0048] Figure 4 shows a method for processing condenser extracted gas according to yet another embodiment.

[0049] In this embodiment, the condensed water in the cooled fluid chamber 25 of the first heat exchanger 10 is passed through line 26 to the OH-type ion exchanger 65, where organic acids and carbonic acid are removed, resulting in a high-pH ammonia solution which is then sent to the deaerator 16 via line 15.

[0050] In this embodiment, the line mixer 32 and scrubber 40 are not installed, and the non-condensable gas in the heat exchanger 10 is drawn in by line 71 and ejector 72 and released into the atmosphere. Water vapor is supplied to the ejector 72 as the working fluid by line 73.

[0051] The other components of Figure 4 are the same as those in Figure 1, and the same part numbers indicate the same parts.

[0052] The above embodiment is just one example of the present invention, and the present invention may take forms other than those shown. For example, gas from line 31 may be diffused into any of the supply water, feedwater, or condensate stored in a vessel (not shown) to dissolve soluble components in water.

[0053] In this invention, multiple OH-type ion exchange devices may be connected in parallel and switched to operate when the acid electrical conductivity of feedwater, main steam, or condensate shows an increasing trend, and the used ion exchange device may be replaced.

[0054] The OH-type ion exchange device may be a cartridge type filled with regenerated ion exchange resin. By using a non-regenerated cartridge type, there is no risk of the regenerating agent (NaOH) being accidentally introduced into the boiler.

[0055] In this invention, if the water temperature passing through the ion exchange device exceeds the durability temperature of the ion exchange resin, the system may switch to a bypass line and temporarily recover the ion exchange resin untreated. Furthermore, if the water pressure is insufficient to pass water through the ion exchange device, a booster pump may be used in conjunction with the ion exchange device.

[0056] In cases where a steam ejector is used in a large-scale power generation facility, multiple (two or more) first heat exchangers 10 for cooling the air extractor may be installed.

[0057] Generally, the condensate from the condensate pump 7 contains almost no carbon dioxide, but it may contain organic acids. In such cases, an ion exchange device 65 may be installed in line 15, and the condensate may also be treated with ion exchange.

[0058] In this invention, ion exchange devices may be individually installed in each line before the confluence. In this invention, a vacuum pump may be used instead of an ejector. In this invention, in the third step of confluence of the water-soluble component dissolved water with the boiler condensate, the water-soluble component dissolved water may be returned to the condenser 5, or confluenced with the water in the line between the outlet of the condenser 5 and the condensate pump 7, thereby confluenced with the condensate. [Explanation of Symbols]

[0059] 1 Boiler 3 Steam Turbine 4 Generators 5. Condenser 10 1st heat exchanger 12 Cooling pipe 22 Ejectors 25 Cooled fluid chamber 32 Line Mixer 40 Scrubber 63 Second heat exchanger 65 OH-type ion exchange device 72 Ejectors

Claims

1. The first step involves cooling the non-condensable gas extracted from the condenser in the first heat exchanger to separate it into condensed water and gas, A second step involves bringing the separated gas into contact with gas absorption water consisting of condensate or pure water in a gas absorption device, thereby dissolving the water-soluble components in the gas in the water. The third step involves combining the water-soluble component-dissolved water from the second step with the boiler condensate. A method for processing condenser extract gas having the following characteristics.

2. The method for treating condenser extract gas according to claim 1, further comprising the step of passing the water-soluble component dissolved water from the second step through an OH-type ion exchange device.

3. The method for treating condenser extracted gas according to claim 2, wherein the water containing dissolved water-soluble components from the second step is cooled in a second heat exchanger, and then passed through the OH-type ion exchange device.

4. The method for treating condenser extracted gas according to claim 3, wherein the second heat exchanger cools the water-soluble component dissolved water with gas absorption water supplied to the gas absorption device.

5. The method for treating condenser extracted gas according to any one of claims 1 to 4, wherein the gas absorption device is at least one of a line mixer and a scrubber.

6. The method for treating condenser extract gas according to claim 1, wherein the condensed water from the first heat exchanger is passed through an OH-type ion exchange device and then combined with the boiler condensate.

7. A gas-liquid separation process is performed in which the non-condensable gas extracted from the condenser is cooled in the first heat exchanger to separate it into condensed water and gas, This condensed water is treated by passing it through an OH-type ion exchange device in an ion exchange treatment process, The process involves combining the water treated by the ion exchange device with the boiler condensate. It has, The aforementioned condensed water contains ammonia, organic acid, and carbonic acid. In the ion exchange treatment step, the organic acid and carbonic acid are removed. A method for treating condenser extract gas, wherein the treated water containing ammonia is combined with the boiler condensate.

8. A first heat exchanger cools the non-condensable gas extracted from the condenser and separates it into condensed water and gas, A gas absorption device that brings the gas separated in the first heat exchanger into contact with gas absorption water consisting of condensate or pure water, and dissolves the water-soluble components in the gas in the water, A means for combining the water-soluble component-dissolved water from the gas absorption device with the boiler condensate. A condenser extraction gas treatment apparatus having [a specific feature].

9. A first heat exchanger cools the non-condensable gas extracted from the condenser and separates it into condensed water and gas, An OH-type ion exchange device through which condensed water from the first heat exchanger is passed, Means for combining the water treated by the ion exchange device with boiler condensate, It has, The aforementioned condensed water contains ammonia, organic acid, and carbonic acid. The OH-type ion exchange apparatus removes the organic acid and carbonic acid, A condenser extract gas treatment device, wherein alkaline treated water containing ammonia is combined with the boiler condensate.

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