Primary and secondary air heater and heating drain collecting and recycling system for thermal power plant

Abstract

The utility model relates to a thermal power plant primary and secondary air heater and heating drain collecting and recycling system, which belongs to the technical field of thermal power plant drain recycling and comprises a primary and secondary air heater, a heating drain tank, a heating heater and a heating drain heater. Drain water of the primary and secondary air heater and drain water of the heating heater are connected to a heating drain water tank through pipelines; the heating drainage heater is provided with a heating return water inlet, a heating return water outlet, a water inlet and a water outlet; the device has the advantages that drain heat of primary and secondary air heater drain and heating drain can be recycled, heating steam supply consumption is reduced, drain can be recycled to the condenser or the chemical fresh water tank, waste of working media is avoided, heat load of the condenser is not increased after the drain is recycled to the condenser, vacuum drop is avoided, and unit operation efficiency is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of drain recovery and utilization in thermal power plants, and particularly relates to a primary and secondary air heater and a heating drain collection and recovery system in a thermal power plant. Background Art

[0002] With the rapid development of my country's national economy, energy demand and energy consumption are increasing day by day. Under the general background of "carbon peak and carbon neutrality", the operation of thermal power plants as energy power producers and consumers is becoming more and more difficult. It is particularly important to improve the efficiency of units and carry out energy-saving transformation. Continuously optimizing the operation and energy-saving transformation of various systems in thermal power plants is of great significance to promoting the high-quality development of the thermal power generation industry.

[0003] In thermal power plants, the drainage design of primary and secondary air heaters adopts a two-way design. One way is to lead the drainage directly to the ditch, and the other way is to lead the drainage directly to the condenser (such as Figure 2 The heater drain is directly led to the ditch, and the drain medium and heat cannot be recycled and are all wasted; and the heater drain is directly led to the condenser, and the drain will carry the heat directly into the condenser, increasing the heat load of the condenser and reducing the vacuum of the condenser.

[0004] In thermal power plants, the design of heating drain recovery is also a two-way method, one way is to lead the heating drain directly to the ditch, and the other way is to lead the heating drain directly to the heating water tank (such as Figure 3 As shown). Normal heating water supply is auxiliary cooling water, which is industrial water and wastewater reuse water, and the water quality requirements are relatively low. Heating drainage is directly led to the heating water supply tank, resulting in the waste of desalted water, increasing the cost of water production and the operating cost of the unit. The heating system drainage is directly led to the ditch, and the drainage medium and heat cannot be recycled and reused, and all are wasted.

[0005] Therefore, a collection and recycling system for primary and secondary air heaters and heating drains in thermal power plants is proposed, which can recycle the drain heat of primary and secondary air heater drains and heating drains, reduce the heating steam consumption, and the drain can be recycled to the condenser or chemical fresh water tank to avoid waste of working fluids. After being recycled to the condenser, the heat load of the condenser is not increased, the vacuum drop is avoided, and the economy of the unit is improved. Summary of the invention

[0006] In view of the above problems, the utility model proposes a collection and recycling system for primary and secondary air heaters and heating drains in a thermal power plant; the primary and secondary air heater drains and heating drains can be collected and then heated for heating return water, the drain heat can be recovered, and the heating steam consumption can be reduced. The cooled drain can be recovered to a condenser or a chemical fresh water tank to avoid waste of working fluids, and the heat load of the condenser will not be increased after being recovered to the condenser, so the vacuum drop can be avoided and the economy of the unit can be improved.

[0007] The utility model embodiment provides a primary and secondary air heater and heating drain collection and recycling system for a thermal power plant, comprising a primary and secondary air heater, a heating drain tank, a heating heater, and a heating drain heater; the drain of the primary and secondary air heater, and the drain of the heating heater are connected to the heating drain tank via pipelines; the heating drain heater is provided with a heating return water inlet, a heating return water outlet, and a water inlet and a water outlet; the bottom of the heating drain tank is connected to the water inlet of the heating drain heater via a pipeline a, so as to input drain into the heating drain heater for heat exchange with heating return water; a heating drain pump a is provided on the pipeline a; the heating return water outlet is connected to the inlet end of the heating heater, and the outlet end of the heating heater is connected to the heating water supply pipe.

[0008] In a preferred embodiment of the present scheme, the water outlet of the heating drain heater is connected to two parallel pipelines, one of which is connected to the condenser and the other is connected to the fresh water tank.

[0009] In a preferred embodiment of the present scheme, an electric valve I and an electric valve II are respectively provided on the pipeline connecting the heating drain heater and the condenser, and on the pipeline connecting the drain heater and the fresh water tank.

[0010] Furthermore, when the water quality at the outlet of the heating drain heater is qualified, the electric valve II is opened, and when the water quality at the outlet of the heating drain heater is unqualified, the electric valves I and II are opened.

[0011] In a preferred embodiment of the present scheme, one end of a circulation pipe b is connected in parallel to an outlet end of the heating drain pump, the other end of the circulation pipe b is connected to the heating drain tank, and an electric door A is also provided on the circulation pipe b.

[0012] In a preferred embodiment of the present scheme, a heating drain pump 2 is also provided on the pipeline a, and the heating drain pump 2 is arranged in parallel with the heating drain pump 1; an electric door B is respectively provided in front and behind the heating drain pump 1, and in front and behind the heating drain pump 2.

[0013] In a preferred embodiment of the present scheme, the outlet pressure of the drain pump 1 or the drain pump 2 is 0.2-0.5 MPa.

[0014] In a preferred embodiment of this scheme, the first and second drain pumps are both driven by variable frequency motors. Thus, the water level of the drain tank can be controlled by variable frequency, effectively reducing the start and stop frequency of the drain pumps, greatly simplifying the system, improving the reliability of equipment operation, and improving the economic efficiency of unit operation to a certain extent.

[0015] In a preferred embodiment of the present scheme, the heating drain heater is a double-tube heat exchanger.

[0016] In a preferred embodiment of the present scheme, the drain of the primary and secondary air heater is connected to the heating drain tank through the heater drain pipe c, and the drain of the heating heater is connected to the heating drain tank through the heater drain pipe d; and the heater drain pipe c and the heater drain pipe d are respectively provided with electric valve III and electric valve IV.

[0017] In a preferred embodiment of the present scheme, the steam inlet end of the primary and secondary air heater is connected in parallel with two pipelines, the two pipelines are respectively connected to five-stage steam extraction and auxiliary steam manifolds, and a solenoid valve is respectively provided on the two pipelines.

[0018] The technical solution of the utility model has at least one of the following beneficial effects: 1) The primary and secondary air heater drain is directly led to the heating drain tank to be collected with the heating drain, and after being pressurized by the heating drain pump 1 (or the spare heating drain pump 2), the drain is subjected to heat exchange with the heating return water through the heating drain heater, the drain is cooled, the heating return water temperature is increased, the drain temperature is reduced, and the cooled drain is led to the condenser or recovered to the chemical fresh water tank, thereby avoiding waste of working fluid, and the heat load of the condenser is not increased after being recovered to the condenser, thereby avoiding vacuum drop and improving the economic efficiency of the unit;

[0019] 2) This technology can be applied to primary and secondary air heaters and heating systems in thermal power plants. When the heating system and primary and secondary air heater system are put into operation in winter, the heating drain and primary and secondary air heater drain working fluid and heat are fully recycled, and the steam consumption for heating in winter is reduced, thereby improving the operating efficiency of the unit;

[0020] 3) This solution adds one heating drain heater, two collecting drain pumps and eight electric valves (one electric door A, four electric doors B, and electric valve I, electric valve II, and electric valve III) to the original system to improve the control convenience.

[0021] Other features and advantages of the utility model will be described in the following description, and partly become apparent from the description, or understood by implementing the utility model. The purpose and other advantages of the utility model can be realized and obtained by the structures indicated in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 The utility model shows a schematic diagram of a primary and secondary air heater and a heating drain collection and recycling system for a thermal power plant;

[0024] Figure 2 A schematic diagram of the primary and secondary air heater drain design according to the prior art is shown;

[0025] Figure 3 A schematic diagram of a heating drain recovery design according to prior art is shown. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] It should be noted that the terms "first", "second" etc. in the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", "longitudinal" etc. are based on the orientation or positional relationship shown in the accompanying drawings.

[0028] The utility model embodiment provides a primary and secondary air heater and heating drain collection and recycling system for a thermal power plant, see Figure 1 As shown, it includes: a primary and secondary air heater 1, a heating drain tank 2, a heating heater 3, a heating drain heater 5, and a heating drain pump 401; the drain of the primary and secondary air heater 1, and the drain of the heating heater 3 are connected to the heating drain tank 2 through pipelines; the heating drain heater 5 can be used to exchange heat between the pressurized drain of the heating drain pump 401 and the heating return water, thereby cooling the drain, increasing the heating return water temperature, and reducing the drain temperature.

[0029] In some embodiments, specifically, the heating drain heater 5 is provided with a heating return water inlet, a heating return water outlet, and a water inlet and a water outlet; the bottom of the heating drain tank 2 is connected to the water inlet of the heating drain heater 5 via a pipe a, so as to input drain into the heating drain heater 5; a heating drain pump 401 is arranged on the pipe a; the heating return water outlet is connected to the inlet end of the heating heater 3, and the outlet end of the heating heater 3 is connected to the heating water supply pipe.

[0030] In some embodiments, the heating drain heater 5 is a double-tube heat exchanger.

[0031] Specifically, the outlet of the heating drain heater 5 is connected to two parallel pipelines, one of which is connected to the condenser, and the other is connected to the fresh water tank. When the drain water quality of the heating drain heater 5 is qualified, the electric valve II9 is ​​opened, and the drain of the heating drain heater 5 is led to the condenser, which will not increase the heat load of the condenser and also recycle the drain; when the water quality is unqualified, the electric valve I8 is opened, and the drain is recycled to the fresh water tank, and then becomes desalted water after chemical desalination treatment, avoiding waste of working fluid.

[0032] In some embodiments, the outlet end of the heating drain pump 401 is also connected in parallel with one end of a circulation pipe b, the other end of the circulation pipe b is connected to the heating drain tank 2, and an electric door A6 is also provided on the circulation pipe b. The setting of the circulation pipe b can be used as a recirculation of the heating drain pump, which is used to control the minimum flow of the heating drain pump and the water level of the heating drain tank.

[0033] In order to ensure the normal operation of the system, a backup pump is also provided in this embodiment, that is, a heating drain pump 2 402 is provided in the pipeline 1a, see Figure 1 As shown, the heating drain pump 2 402 is arranged in parallel with the heating drain pump 1 401; and an electric door B7 is respectively provided in front and behind the heating drain pump 1 401, and in front and behind the heating drain pump 2 402.

[0034] Furthermore, in some embodiments, the drain of the primary and secondary air heater 1 is connected to the heating drain tank 2 through the heater drain pipe c, and the drain of the heating heater 3 is connected to the heating drain tank 2 through the heater drain pipe d; and the heater drain pipe c and the heater drain pipe d are respectively provided with electric valve III10 and electric valve IV11.

[0035] In some embodiments, see Figure 1 As shown, the steam inlet end of the primary and secondary air heater 1 is connected in parallel with two pipelines, the two pipelines are respectively connected with five-stage steam extraction and auxiliary steam headers, and a solenoid valve is respectively provided on the two pipelines.

[0036] In some embodiments, the temperature of the primary and secondary air heater drain and the heating drain is 80-90°C. After being pressurized by drain pump 1 401 or drain pump 2 402 and passing through the heating drain heater 5, the heating return water temperature can be increased by 3-5°C. After passing through the heating drain heater 5, the collected drain temperature can be reduced to 35-40°C (close to the condensate temperature). When the collected drain water quality after cooling is qualified, it is led to the condenser, which neither increases the heat load of the condenser nor recovers all the drain water. When the water quality is unqualified, it is recovered to the fresh water tank and then becomes desalted water after chemical desalination treatment. The above entire heating system and heater system commissioning process will not cause any heat loss and working fluid waste. The increase in the heating return water temperature also reduces the steam consumption of heating and improves the efficiency of the unit operation.

[0037] In some embodiments, the outlet pressure requirement of the drain pump is relatively low, 0.2-0.5 MPa is sufficient; and both the drain pump 1 401 and the drain pump 2 402 are driven by variable frequency motors. The frequency conversion method is used to control the water level of the drain tank, which effectively reduces the start and stop frequency of the drain pump, greatly simplifies the system, improves the reliability of equipment operation, and improves the economic efficiency of unit operation.

[0038] The working process of the embodiment of the utility model is described in detail below with reference to the accompanying drawings.

[0039] refer to Figure 1 As shown, in the embodiment of the utility model, the drain from the primary and secondary air heaters 1 is directly led to the heating drain tank 2 to be collected with the heating drain, and then is pressurized by the heating drain pump 1 401 (or the spare heating drain pump 2 402) and transported to the heating drain heater 5 as a thermal fluid to exchange heat with the heating return water. The heating return water heated by the heating drain heater 5 enters the water supply and heating pipeline, and the drain cooled by the heating drain heater 5 enters the condenser or the chemical fresh water tank; at the same time, during the process of the heating drain pump 1 401 (or the heating drain pump 2 402) pumping the liquid, the heating drain pump 1 401 (or the heating drain pump 2 402) adopts frequency conversion control and cooperates with the electric valve A6 to realize the water level control in the heating drain tank 2.

[0040] The technical solution of the utility model has at least one of the following beneficial effects:

[0041] 1) The primary and secondary air heater drain is directly led to the heating drain tank and collected with the heating drain. After being pressurized by the heating drain pump 1 (or the spare heating drain pump 2), it passes through the heating drain heater to exchange heat with the heating return water, cools the drain, increases the heating return water temperature, and reduces the drain temperature. The cooled drain is led to the condenser or recovered to the chemical fresh water tank to avoid waste of working fluid. After being recovered to the condenser, the heat load of the condenser is not increased, the vacuum drop is avoided, and the unit economy is improved;

[0042] 2) This technology can be applied to primary and secondary air heaters and heating systems in thermal power plants. When the heating system and primary and secondary air heater system are put into operation in winter, the heating drain and primary and secondary air heater drain working fluid and heat are fully recycled, and the steam consumption for heating in winter is reduced, thereby improving the operating efficiency of the unit;

[0043] 3) This solution adds one heating drain heater, two collecting drain pumps and eight electric valves (one electric door A, four electric doors B, and electric valve I, electric valve II, and electric valve III) to the original system to improve the control convenience.

[0044] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A primary and secondary air heater and heating drain collection and recycling system for a thermal power plant, characterized in that: include: Primary and secondary air heater (1), heating drain tank (2), heating heater (3), heating drain heater (5); The drain of the primary and secondary air heater (1) and the drain of the heating heater (3) are both connected to the heating drain tank (2) via pipelines; The heating drain heater (5) is provided with a heating return water inlet, a heating return water outlet, a water inlet and a water outlet; The bottom of the heating drain tank (2) is connected to the water inlet of the heating drain heater (5) via a pipe (a), and drain water is input into the heating drain heater (5) for heat exchange with heating return water; The pipeline (a) is provided with a heating drain pump (401); The heating return water outlet is connected to the inlet end of the heating heater (3), and the outlet end of the heating heater (3) is connected to the heating water supply pipe.

2. A primary and secondary air heater and heating drain collection and recycling system for a thermal power plant according to claim 1, characterized in that: The heating drain heater (5) is connected to two parallel pipelines, wherein one pipeline of the heating drain heater is connected to a condenser, and the other pipeline is connected to a fresh water tank.

3. A primary and secondary air heater and heating drain collection and recycling system for a thermal power plant according to claim 2, characterized in that: The pipeline connecting the heating drain heater (5) and the condenser, and the pipeline connecting the drain heater (5) and the fresh water tank are respectively provided with an electric valve I (8) and an electric valve II (9).

4. A primary and secondary air heater and heating drain collection and recycling system for a thermal power plant according to claim 3, characterized in that: When the water quality at the outlet of the heating drain heater (5) is qualified, the electric valve II (9) is opened; when the water quality at the outlet of the heating drain heater (5) is unqualified, the electric valve I (8) and the electric valve II (9) are opened.

5. A primary and secondary air heater and heating drain collection and recycling system for a thermal power plant according to claim 2, characterized in that: The outlet end of the heating drain pump 1 (401) is also connected in parallel with one end of a circulation pipe (b), the other end of the circulation pipe (b) is connected to the heating drain tank (2), and an electric door A (6) is also provided on the circulation pipe (b).

6. A primary and secondary air heater and heating drain collection and recycling system for a thermal power plant according to claim 5, characterized in that: The pipeline 1 (a) is also provided with a heating drain pump 2 (402), and the heating drain pump 2 (402) is arranged in parallel with the heating drain pump 1 (401); An electric door B (7) is respectively provided at the front and rear of the heating drain pump 1 (401) and at the front and rear of the heating drain pump 2 (402).

7. A primary and secondary air heater and heating drain collection and recycling system for a thermal power plant according to claim 6, characterized in that: The outlet pressure of the drain pump 1 (401) or the drain pump 2 (402) is 0.2-0.5 MPa.

8. A primary and secondary air heater and heating drain collection and recycling system for a thermal power plant according to claim 7, characterized in that: The drain pump 1 (401) and the drain pump 2 (402) are both driven by variable frequency motors.

9. A primary and secondary air heater and heating drain collection and recycling system for a thermal power plant according to any one of claims 1 to 8, characterized in that: The heating drain heater (5) is a double-tube heat exchanger.

10. A primary and secondary air heater and heating drain collection and recycling system for a thermal power plant according to claim 9, characterized in that: The drain of the primary and secondary air heater (1) is connected to the heating drain tank (2) through the heater drain pipe (c), and the drain of the heating heater (3) is connected to the heating drain tank (2) through the heater drain pipe (d); The heater drain pipe (c) and the heater drain pipe (d) are respectively provided with an electric valve III (10) and an electric valve IV (11).

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