CN102408148A - Feed water treatment method for thermal generator set - Google Patents

Abstract

The invention discloses a water supply treatment method for a thermal generator set, belonging to the technical field of electric power and power engineering. The method comprises the following steps: the oxidant is added in front of the low-pressure heater or/and in front of the high-pressure heater, so that the flow accelerated corrosion in a water supply system can be inhibited; and adding a reducing agent behind the high-pressure heater to react with the oxidizing agent, so that the concentration of dissolved oxygen in boiler water of the boiler system is lower than a preset value, and removing the enhancement effect of oxygen on the metal oxidation rate of the boiler pipe in the oxygen adding treatment. The method can inhibit the flow accelerated corrosion of the water supply system and reduce the oxygen corrosion of the inner wall of the boiler tube at the same time.

Description

A kind of thermal power generation unit feed water treatment method

technical field

The invention belongs to the technical field of electric power and power engineering, and in particular relates to a method for treating feed water of a thermal power generating set.

Background technique

At present, there are two main methods of water treatment for super (super) critical thermal power generating units: full volatile treatment (AVT) and oxygenation treatment (OT). AVT advocates removing oxygen in the system and inhibiting oxygen corrosion, including AVT(R) and AVT(O). OT advocates adding oxygen to the system to form a protective oxide layer. Both of these feedwater treatment methods are implemented for the entire system (including low-pressure heaters, high-pressure heaters, and boiler tube systems).

When the ultra (ultra) critical thermal power generation unit adopts the AVT method, flow accelerated corrosion (FAC) occurs in the feed water system such as the low pressure heater and the high pressure heater, so that the content of iron ions in the feed water entering the boiler is relatively high. The hydraulic fluid changes from a subcritical state to a supercritical state in the boiler, and its physical properties undergo many changes, from polar to nonpolar. Therefore, the iron ions in the furnace water are precipitated in the water wall, superheater and other pipes, and then form an oxide layer.

In order to overcome the shortcomings of the AVT method, an oxygenation treatment method was created. Oxygenation treatment Adding oxygen to the feed water can form a dense oxide layer on the metal surface, effectively inhibiting the flow-accelerated corrosion of feed water systems such as low-pressure heaters and high-pressure heaters, and reducing the content of iron ions in the feed water entering the boiler. With the application of oxygenation treatment in super (super) critical units, it is found that in some power plants, the oxide layer formation rate in the superheater and reheater pipes is too fast, and pipe overheating, oxide layer peeling, plugging and bursting of pipes and blade erosion have occurred. A series of problems such as eclipse.

Therefore, the feedwater treatment method in the prior art cannot suppress the flow-accelerated corrosion of the feedwater system and reduce the corrosion of the inner wall of the boiler tube at the same time.

Contents of the invention

The present invention is proposed in view of the above problems of the prior art. The invention provides a method for treating feed water of a thermal power generating set, which can simultaneously suppress the flow-accelerated corrosion of the feed water system and reduce the corrosion of the inner wall of the boiler tube.

A method for treating feed water of thermal power generating units provided by the present invention includes: adding an oxidizing agent before the low-pressure heater or/and before the high-pressure heater; value.

Preferably, adding the reducing agent after the high pressure heater includes one or more of the following methods:

Method 1: After the outlet of the high-pressure heater, add the reducing agent to the pipeline in front of the economizer;

Method 2: Add reducing agent at the lower header of the water wall.

Preferably, the method further includes: adjusting the adding amount of the reducing agent according to the dissolved oxygen monitoring at the inlet of the economizer and the feedwater flow signal, or adjusting the adding amount of the reducing agent according to the amount of dissolved oxygen at the inlet of the economizer and the adding amount of the oxidant.

Preferably, adding the reducing agent after the high-pressure heater includes: using a high-pressure pump to inject the reducing agent after the high-pressure heater.

Preferably, adding the oxidizing agent before the low-pressure heater or/and before the high-pressure heater includes one or more of the following methods:

Method 1: Add an oxidizing agent to the outlet main pipe of the condensate polishing mixed bed;

Method 2: Add oxidant at the downcomer at the outlet of the deaerator;

Method 3: Add the oxidant to the outlet main pipe of the condensate polishing mixed bed, and add the oxidant to the downcomer at the outlet of the deaerator.

Preferably, the oxidant is added before the low-pressure heater or/and the high-pressure heater so that the dissolved oxygen concentration in the water supply system is 30-150 μg/L.

Preferably, the reducing agent is added after the high-pressure heater to react with the oxidizing agent, so that the dissolved oxygen at the inlet of the economizer is less than a predetermined value of 7 μg/L.

According to the feed water treatment method provided by the present invention, by adding an oxidizing agent before the low-pressure heater or/and before the high-pressure heater, the flow-accelerated corrosion in the feed water system can be suppressed; by adding a reducing agent after the high-pressure heater, the boiler water in the boiler system If the dissolved oxygen concentration is lower than the predetermined value, the enhanced effect of high oxygen on the oxidation rate of the boiler tube metal can be removed. Therefore, it is possible to simultaneously inhibit the flow-accelerated corrosion of the water supply system and reduce the corrosion of the inner wall of the boiler tube.

The present invention also provides a complete set of high-pressure adding reducing agent applied to the above method. The device includes: a liquid storage tank, which is used to store the reducing agent solution; a high-pressure liquid metering pump, whose inlet is connected to the liquid storage tank, and the outlet can be connected to The boiler tube system behind the high-pressure heater is used to receive flow control instructions from the controller, and adjust the output flow of the reducing agent according to the flow control instructions; the controller is connected to the high-pressure liquid metering pump and used to meter the high-pressure liquid The pump sends a flow control command so that the dissolved oxygen concentration of the boiler water in the boiler tube system is lower than the predetermined value.

Preferably, a buffer tank, a pressure gauge, a pressure reducing valve, a gate valve and a check valve are sequentially connected between the outlet of the high-pressure liquid metering pump and the boiler pipe system; a filter is arranged between the liquid storage tank and the high-pressure liquid metering pump .

Preferably, the system further includes: an automatic dispensing device, which is connected to the liquid storage tank and used to provide the concentrated reducing agent solution and dilution water to the liquid storage tank to form a reducing agent solution.

Preferably, the automatic dispensing device includes a reductant barrel, a liquid pump, a reductant flow meter and a reductant gate valve connected in sequence, and the reductant gate valve is connected with the liquid storage tank; it also includes a dilution water source, a dilution water flow meter and a dilution water source connected in sequence. Water gate valve, the dilution water gate valve is connected with liquid storage tank.

Preferably, the system also includes an automatic dispensing controller, which is connected with the automatic dispensing device, and is used to provide a ratio signal of the reductant concentrated solution and dilution water, and send instructions to the electric valve, controlled by the reductant flowmeter and the dilution water flowmeter Ratio of concentrated reducing agent solution and dilution water.

Preferably, the liquid storage tank includes a stirrer for stirring the concentrated reducing agent solution and dilution water to form a reducing agent solution.

The invention also provides a water supply treatment system for a thermal power generating set, which can suppress the flow-accelerated corrosion of the water supply system and reduce the corrosion of the inner wall of the boiler tube. The system includes: an oxidant adding device, used to add oxidant before the low pressure heater or/and before the high pressure heater; a reducing agent adding device, used to add the reducing agent after the high pressure heater, so that the concentration of dissolved oxygen in the furnace water of the boiler system is low at the predetermined value. The reducing agent adding device is the above-mentioned high-pressure reducing agent adding device.

Preferably, the oxidant adding device can be installed at any one or more of the following positions: position 1, the oxidant adding device is located at the outlet main pipe of the condensate polishing mixed bed; position 2, the oxidant adding device is located at the outlet downcomer of the deaerator ; Position three, the oxidant adding device is located at the main pipe outlet of the condensate polishing mixed bed outlet and the downcomer outlet of the deaerator.

Preferably, the reducing agent adding device can be installed at any one or more of the following positions. In position 1, the reducing agent adding device is located after the outlet of the high-pressure heater and on the pipeline in front of the economizer; in position 2, the reducing agent adding device is located in the water-cooled Under the wall at the header.

The main application objects of the thermal power generating set feedwater treatment method, the high-pressure adding reducing agent complete set and the thermal generating set feedwater treatment system are super (super) critical thermal generating sets.

According to the feedwater treatment system provided in one aspect of the present invention, the oxidant adding device can suppress the flow-accelerated corrosion in the feedwater system by adding the oxidant before the low-pressure heater or/and before the high-pressure heater; After adding the reducing agent, the dissolved oxygen concentration of the boiler water in the boiler system is lower than the predetermined value, which can remove the enhancement effect of oxygenation treatment on the metal oxidation rate of the boiler tube, thereby simultaneously inhibiting the flow-accelerated corrosion of the water supply system and reducing the corrosion of the inner wall of the boiler tube.

Description of drawings

The accompanying drawings, which constitute a part of this specification, illustrate the embodiments of the invention and together with the description serve to explain the principles of the invention.

The present invention can be more clearly understood from the following detailed description with reference to the accompanying drawings, in which:

Fig. 1 shows the flow chart of an embodiment of super (super) critical thermal power generating unit feedwater treatment method of the present invention;

Fig. 2 shows the structural diagram of an embodiment of the super (super) critical thermal power generating unit feedwater treatment system of the present invention;

Fig. 3 shows the structural diagram of another embodiment of the super (super) critical thermal power generation unit feedwater treatment system of the present invention;

Fig. 4 shows the structural diagram of an embodiment of the high pressure plus reducing agent complete set of the present invention;

Fig. 5 shows the structural diagram of another embodiment of the high pressure plus reducing agent complete set of the present invention;

Fig. 6 shows the flow chart of determining the addition amount of reducing agent by the controller in one embodiment of the present invention;

Fig. 7 shows a flow chart of the controller determining the adding amount of reducing agent in another embodiment of the present invention.

Detailed ways

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangements of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

At the same time, it should be understood that, for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

The following description of at least one exemplary embodiment is merely illustrative in nature and in no way taken as limiting the invention, its application or uses.

Techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods and devices should be considered part of the Authorized Specification.

In all examples shown and discussed herein, any specific values should be construed as illustrative only, and not as limiting. Therefore, other examples of the exemplary embodiment may have different values.

It should be noted that like numerals and letters denote like items in the following figures, therefore, once an item is defined in one figure, it does not require further discussion in subsequent figures.

The application of oxygenation treatment makes the inner wall of some boiler tubes such as boiler water wall and superheater be in the dissolved oxygen supercritical water environment. Whether the oxidation of pipeline materials in this environment is suppressed or strengthened is an international research in recent years. hotspot. The present inventors selected iron martensitic steel P92, austenitic steel Super304H, TP347HFG, HR3C and low-alloy heat-resistant steel T24 five typical steels for ultra-supercritical unit boiler tubes as objects, exposed to 550 ℃, 600 ℃, 25MPa ultra- In the critical water, experiments were carried out on different dissolved oxygen concentrations of anaerobic, 100ppb, 300ppb, and 2000ppb. The results show that the oxidation rate of the above five steel types increases with the increase of dissolved oxygen in supercritical water. Even though some steel types formed a dense protective film in a short-term test in a high-oxygen environment, and the oxidation rate was relatively low, the law that the oxidation rate increased with the increase of dissolved oxygen was also obtained in the long-term test. Therefore, according to the experimental research conclusion, in order to suppress the oxidation rate of the boiler tube, the amount of dissolved oxygen in the feed water entering the boiler should be reduced.

Fig. 1 shows a flow chart of an embodiment of a method for treating feed water of a super (super) critical thermal power generating unit according to the present invention.

As shown in FIG. 1 , in step 102 , an oxidizing agent is added before the low pressure heater or/and before the high pressure heater. The oxidizing agent can be, for example, pure oxygen or a mixed gas containing oxygen. For example, one or more of the following methods are adopted: method 1, adding oxidant to the outlet main pipe of the condensate polishing mixed bed; method 2, adding oxidant to the downcomer at the outlet of the deaerator; The oxidant is added to the outlet main pipe of the fine treatment mixed bed, and the oxidant is added to the downcomer at the outlet of the deaerator.

Step 104, adding a reducing agent after the high-pressure heater, so that the dissolved oxygen concentration of the boiler water in the boiler system is lower than a predetermined value. For example, one or several of the following methods are adopted: Method 1, adding reducing agent to the pipeline before the economizer after the high-pressure heater; Method 2, adding reducing agent to the lower header of the water wall. The reducing agent can be injected by means of a high-pressure pump, and the reducing agent can be hydrazine.

In the above-mentioned embodiments, by adding an oxidizing agent before the low-pressure heater or/and before the high-pressure heater, the flow-accelerated corrosion in the water supply system can be suppressed; by adding a reducing agent after the high-pressure heater, the dissolved oxygen concentration of the boiler water in the boiler system can be reduced. If it is lower than the predetermined value, the enhancement effect of oxygenation treatment on the metal oxidation rate of boiler tubes can be eliminated, so that the flow-accelerated corrosion of the feed water system and the corrosion of the inner wall of the boiler tube can be suppressed at the same time. Advantages of permanent treatment to reduce high temperature oxidation of boiler tubes.

In one embodiment of the present invention, an oxidizing agent is added before the low-pressure heater or/and high-pressure heater so that the dissolved oxygen concentration in the water supply system is 30-150 μg/L, and a reducing agent is added after the high-pressure heater so that the furnace in the boiler system The dissolved oxygen concentration of the water is lower than 7μg/L. Those skilled in the art should understand that an oxidizing agent or a reducing agent can be added as needed, so that the dissolved oxygen concentration in the water supply system is within a predetermined range.

Fig. 2 shows the structural diagram of an embodiment of the super (super) critical thermal power generation unit feed water treatment system of the present invention.

Referring to Fig. 2, in this embodiment, the oxidant is added to the water supply system at the oxygenation point 20 of the condensate fine treatment mixed bed outlet main pipe, and the oxidant can also be added to the oxygenation point 21 of the downcomer outlet at the outlet of the deaerator to control the water supply system The concentration of dissolved oxygen in the medium is within a predetermined range, such as 30-150 μg/L.

After the hydraulic fluid comes out of the condensate polishing device 3, it flows through the low-pressure heater 4, the deaerator 8, the feed water pump 9, and the high-pressure heater 10. In the above water supply system, the dissolved oxygen concentration of the hydraulic fluid is required to be kept at 30 -150μg/L, to inhibit flow-accelerated corrosion.

A reducing agent is added at the ammonia addition point 22 of the outlet pipeline of the high-pressure heater 10, and the reducing agent and dissolved oxygen react in the pipeline along the pipeline from the outlet of the high-pressure heater 10 to the economizer 13, so that the concentration of dissolved oxygen decreases, and at the inlet of the economizer The water intake point 23 monitors the dissolved oxygen level, controls the ammonia addition point 22 to add reducing dose according to the dissolved oxygen concentration, and controls the dissolved oxygen concentration to be less than a predetermined value, such as 7 μg/L.

The feed water after deoxygenation flows through economizer 13, water wall 14, superheater 15, steam turbine high-pressure cylinder 16, reheater 17, and in above soda-water system, the dissolved oxygen concentration of hydraulic fluid is kept at predetermined value (for example 7 μ g/ L) Below, avoid oxygen in supercritical water environment and high-temperature steam environment to the strengthening effect of metal oxidation rate. Reference numeral 18 represents a medium-pressure cylinder, reference numeral 19 represents a low-pressure cylinder, reference numeral 1 represents a condenser, and reference numeral 2 represents a condensate pump.

In the above-mentioned embodiment, an oxidizing agent (pure oxygen can be used) is added to the outlet main pipe of the condensate polishing treatment mixed bed, and an oxidizing agent can also be added to the position of the downcomer at the outlet of the deaerator, and a reducing agent can be added to the outlet pipe of the high-pressure heater (which can be used Hydrazine), so that the dissolved oxygen concentration is maintained at 30-150 μg/L in the water supply system such as low-pressure heater and high-pressure heater, and the reductant and oxidant react according to the following reaction formula in the pipeline from the high-pressure heater to the economizer (with Hydrazine and oxygen as an example):

N ₂ H ₄ +O ₂ =2H ₂ O+N ₂ (1)

Oxygen is removed so that the dissolved oxygen concentration in the boiler water entering the economizer is lower than 7μg/L.

Since the pipeline from the high-pressure heater to the economizer is tens of meters long, and the temperature in the pipeline is 230-280°C, the reaction formula (1) reacts quickly and can be completely reacted.

During the start-up and shutdown of the generator set, the water treatment shall refer to the relevant operation rules. After the water index is qualified, after switching to oxygenation treatment, the water supply treatment method of the present invention can be adopted.

Fig. 3 shows the structural diagram of another embodiment of the super (super) critical thermal power generation unit feed water treatment system of the present invention. In the embodiment of Fig. 3, the oxidant is added to the water supply system at the oxygenation point 20 of the condensate fine treatment mixed bed outlet main pipe, and the oxidant can also be auxiliary added at the downcomer at the outlet of the deaerator, and added at 24 at the lower header of the water wall reducing agent.

By adding a reducing agent at the lower header of the water wall, the effect of adding oxygen on the low-pressure heater, high-pressure heater to the economizer can be maintained to inhibit the flow and accelerate corrosion, and in the steam-water system after the water wall 14, the water working medium dissolves The oxygen concentration is kept below a predetermined value to avoid the enhancement effect of oxygen on the metal oxidation rate in the supercritical water environment and the high temperature steam environment.

In Fig. 3 and Fig. 4, at the oxygen addition point 20 of the oxygen addition point 20 of the outlet main pipe of the condensate polishing treatment mixed bed and the oxygen addition point 21 of the downcomer outlet of the deaerator, the oxidant addition device can be used before the low-pressure heater or/and Add oxidant before the high-pressure heater; add reducing agent after the high-pressure heater through the reducing agent adding device at the ammonia adding point 22 of the high-pressure heater outlet pipeline and the lower header of the water wall 24, so that the dissolved oxygen in the furnace water of the boiler system The concentration is lower than the predetermined value. The oxidizing agent adding device can adopt the device and equipment of the prior art, and also can use the device and equipment specially designed for the application. The reducing agent adding device can adopt the high-pressure reducing agent adding device introduced in the present invention.

The hydraulic fluid after the high-pressure heater is at a high pressure, for example, the pressure is about 26-30MPa for an ultra-supercritical unit, so the whole set of equipment that requires the addition of a reducing agent is a high-pressure system, especially the high-pressure liquid metering pump, high-pressure liquid metering The pump can be a plunger pump, such as a high-pressure metering pump model PREP250 from SSI Company, with a flow rate of 0.1-250 mL/min and an accuracy of 2% F.S.

Referring to Fig. 4 and Fig. 5, the specific embodiment of the complete set of high-pressure adding reducing agent of the present invention will be described below.

Fig. 4 shows a structural diagram of an embodiment of the high-pressure plus reducing agent complete set of the present invention. As shown in FIG. 4 , the complete set includes a liquid storage tank 41 , a high-pressure liquid metering pump 42 and a controller 43 . The liquid storage tank 41 stores a reducing agent solution. The reducing agent can be hydrazine, and hydrazine can be a pure solution or a diluted solution. The inlet of the high-pressure liquid metering pump 42 is connected to the liquid storage tank 41, and the outlet can be connected to the boiler system behind the high-pressure heater. Reductant output flow to boiler system. The controller 43 is connected to the high-pressure liquid metering pump 42 through a data line, and sends a flow control command to the high-pressure liquid metering pump 42 so that the concentration of dissolved oxygen in the boiler tube system is lower than a predetermined value, for example, 7 μg/L. For example, the controller 43 receives the dissolved oxygen monitoring signal a at the inlet of the economizer and the feedwater flow signal c, and outputs a flow control command to the high-pressure liquid metering pump 42 according to the control logic, and the high-pressure liquid metering pump 42 automatically adjusts the flow output; or the controller 43 Receive the monitoring signal a of dissolved oxygen at the inlet of the economizer and the signal b of the oxygen adding device, output flow control instructions to the high-pressure liquid metering pump 42 according to the control logic, and the high-pressure liquid metering pump 42 automatically adjusts the flow output.

At present, there are many high-pressure liquid metering pumps, and plunger pumps can be used. The working pressure is about 35MPa, for example, and the flow rate is about 250ml/min. The outlet pressure of the high-pressure liquid metering pump 42 can be set, the flow rate can be continuously adjusted, and the flow control accuracy can reach about 2% F.S. The liquid storage tank 41 can be equipped with an agitator 49 (such as an electric agitator), and the impeller and shaft of the agitator 49 can be made of stainless steel. The agitator 49 can realize timing start and stop, the start and stop time can be set, and the speed of the agitator 49 is adjustable. The liquid storage tank 41 has good sealing performance, and the top of the tank can be equipped with a respirator to prevent the reducing agent from volatilizing into the room. The liquid storage tank 41 can be made of stainless steel.

According to an embodiment of the present invention, a filter 48 is connected between the liquid storage tank 41 and the high-pressure liquid metering pump 42 to filter the reducing agent solution added to the water supply system through the high-pressure liquid metering pump 42 . A buffer tank 44 , a pressure gauge 45 , a pressure reducing valve 46 , a check valve 47 and a gate valve are sequentially connected between the high-pressure liquid metering pump 42 and the reducing agent addition point of the boiler tube system.

Fig. 5 shows a structural view of another embodiment of the high-pressure plus reducing agent complete set of the present invention. In this embodiment, taking two units as an example, the high-pressure plus reducing agent complete set includes two liquid storage tanks 41 , three high-pressure liquid metering pumps 42 (one spare), an automatic dosing system 500 and a controller 43 . The automatic dispensing device 500 is connected to the liquid storage tank 41 and is used to provide the concentrated reductant solution and dilution water to the liquid storage tank 41 to form a reductant solution.

Referring to FIG. 5 , according to an embodiment of the present invention, an automatic dispensing device 500 includes a reductant barrel 51 , a liquid extraction pump 53 , a reductant flow meter 54 , and gate valves 55 and 56 connected in sequence, and the gate valve 55 is connected to the liquid storage tank 41 The automatic dispensing device 500 also includes a dilution water source 52, a dilution water flow meter 59, and a dilution water gate valve 60 connected in sequence, and the dilution water gate valve 60 is connected to the liquid storage tank 41. The stirrer 49 of the liquid storage tank 41 can stir the concentrated reducing agent solution and the dilution water. The liquid storage tank 41 is equipped with a liquid level gauge 50, which is used for liquid level monitoring. The liquid level is displayed on the spot and has a DC signal output, and has a high and low level alarm function. The solution tank is equipped with sewage discharge, water inlet, liquid inlet, liquid outlet and other interfaces. There is an electric valve 58 at the outlet of the liquid storage tank 41, and the valve is closed when the solution is configured, so as to avoid the influence of uneven concentration on the dosing.

In one embodiment, the complete set of high-pressure adding reducing agent further includes an automatic dispensing controller 57 connected to the automatic dispensing device 500 for providing ratio signals of concentrated reducing agent solution and dilution water. The automatic dispensing device 500 is controlled by the automatic dispensing controller 57, and the dispensing process can be carried out automatically or manually. The dispensing concentration can be set. According to the set value, the automatic dispensing controller 57 sends an instruction to the electric valve to provide the proportioning signal of the reductant concentrated solution and the dilution water. Dilution water ratio. Automatic dispensing controller 57 may be located on the same computing device as controller 43 .

In Figure 5, the automatic dispensing device is a complete automatic dispensing system, which can be operated automatically by remote control or manually. There are 2 liquid storage tanks, one is running, and the other is dispensing, and it will be used for standby after dispensing. There are 3 high-pressure liquid metering pumps, 2 in normal operation and 1 in standby. The whole set of system pipes, valves and other equipment are made of stainless steel, and the pressure resistance level is selected according to the high-pressure liquid metering pump. Control the flow rate of the reducing dose of the high-pressure liquid metering pump so that the dissolved oxygen at the inlet of the economizer is less than the predetermined value, such as ≤7μg/L; the operation data is automatically stored and counted, and the operation data curve is given.

According to an embodiment of the present invention, the adding amount of the reducing agent can be adjusted according to the dissolved oxygen amount at the inlet of the economizer and the feedwater flow signal, or the adding amount of the reducing agent can be adjusted according to the amount of dissolved oxygen at the inlet of the economizer and the added amount of the oxidant. The control of the addition amount of the reducing agent will be described below with reference to FIGS. 6 and 7 .

Fig. 6 shows a flow chart of the controller determining the adding amount of reducing agent in one embodiment of the present invention.

As shown in FIG. 6 , in step 602 , the reductant filling amount is calculated according to the monitoring result of the dissolved oxygen amount at the inlet of the economizer and the feed water flow.

Step 604, the high-pressure metering pump controls the filling amount of the reducing agent.

Step 606, judge whether the dissolved oxygen at the inlet of the economizer satisfies the predetermined value, if so, end, otherwise, go to step 604 to continue the reducing agent addition control.

Fig. 7 shows a flow chart of the controller determining the adding amount of reducing agent in another embodiment of the present invention.

As shown in FIG. 7 , in step 702 , the filling amount of the reducing agent is calculated according to the monitoring result of the oxygen filling amount of the oxygen adding device and the dissolved oxygen amount at the inlet of the economizer.

Step 704, the high-pressure metering pump controls the filling amount of the reducing agent.

Step 706, judge whether the dissolved oxygen at the inlet of the economizer satisfies the predetermined value, if yes, end, otherwise, go to step 704 to continue the reducing agent addition control.

So far, the feedwater treatment method and system according to the present invention, and the high-pressure reducing agent packaged device applied to the method and system of the present invention have been described in detail. Certain details well known in the art have not been described in order to avoid obscuring the inventive concept. Based on the above description, those skilled in the art can fully understand how to implement the technical solutions disclosed herein.

The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and changes will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to better explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention and design various embodiments with various modifications as are suited to the particular use.

Claims (10)

1. thermal power generation unit feedwater treatment method is characterized in that this method comprises:

Add oxygenant before low pressure heater or/and before the high pressure heater;

Behind said high pressure heater, add reductive agent, make boiler systems stove oxygen in water concentration be lower than preset value.

2. method according to claim 1 is characterized in that, the adding reductive agent comprises one or more in the following mode behind said high pressure heater:

Mode one, in said high pressure heater outlet back, on the economizer preceding pipeline, add said reductive agent;

Mode two, add said reductive agent at water wall lower collecting box place.

3. method according to claim 2 is characterized in that, also comprises:

Regulate said reductive agent add-on according to economizer inlet dissolved oxygen monitoring point signal and feedwater flow, perhaps regulate said reductive agent add-on according to economizer inlet dissolved oxygen content and said oxygenant add-on.

4. method according to claim 1 is characterized in that, adopts the HPP mode behind said high pressure heater, to inject said reductive agent.

5. according to any described method in the claim 1 to 4, it is characterized in that the adding oxygenant comprises one or more in the following mode before low pressure heater or/and before the high pressure heater:

Mode one, mix the female pipe of a bed outlet place in the condensed water precision processing and add said oxygenant;

Mode two, add said oxygenant at the deoxygenator pipe place that falls in export;

Mode three, mix the female pipe of a bed outlet place in the condensed water precision processing and add said oxygenant, falling in export at deoxygenator, the pipe place is auxiliary to add said oxygenant.

6. according to any described method in the claim 1 to 3, it is characterized in that, make that dissolved oxygen concentration is 30-150 μ g/L in the water feeding system or/and add oxygenant before the said high pressure heater at said low pressure heater.

7. method according to claim 1 is characterized in that, described preset value is 7 μ g/L.

8. method according to claim 1 is characterized in that, said oxygenant is a pure oxygen, perhaps for comprising the mixed gas of oxygen.

9. method according to claim 1 is characterized in that, said reductive agent is a diamine.

10. method according to claim 9 is characterized in that, said reductive agent is the pure solution of diamine, or the solution of dilution.

Images