Energy-saving improvement methods for closed-loop water heat exchanger cooling after unit shutdown

Abstract

The present invention belongs to the field of new energy and energy-saving technology, and specifically relates to an energy-saving improvement method for the cooling mode of a closed water heat exchanger after the unit is shut down. An energy-saving improvement method for the cooling mode of a closed water heat exchanger after the unit is shut down, comprising the following steps: retaining one water pump in the first circulating water pump unit for operation, and when the temperature of the inner cylinder in front of the high and medium pressure cylinder is less than the preset temperature value, destroying the vacuum; shutting down the currently running water pump of the first circulating water pump unit, closing the outlet butterfly valve of the first circulating water pump unit; closing the condenser circulating water return butterfly valve; running the second circulating water pump unit, and continuously providing cooling circulating water to the closed water heat exchanger through the seawater chlorine production and dosing pipeline. After the vacuum is broken, the circulating water pump can be shut down, saving a large amount of factory electricity, and no equipment modification is required, and no additional costs are required.

Description

Technical Field

[0001] The invention belongs to the technical field of new energy and energy saving, and specifically relates to an energy-saving improvement method for the cooling mode of a closed water heat exchanger after a unit is shut down. Background Art

[0002] The circulating water supply method for the 2×350MW generating units of the first phase of Rizhao Power Plant is that each unit has two circulating water pumps that supply seawater to the condenser and closed water heat exchanger as cooling water.

[0003] After the unit is shut down, keep one circulating water pump running. When the temperature of the front inner cylinder of the high and medium pressure cylinders is less than 300℃, the vacuum is destroyed; the average temperature of the high and medium pressure rotors and the average temperature of the inner cylinder of the high pressure cylinder are both less than 120℃, stop the cranking operation, shut down the large engine oil system, and shut down all the equipment on the machine side. Only then can the circulating water pump and the closed water system be shut down.

[0004] The circulating water pump of the first phase unit is an AEZ1600-1480 mixed flow pump with a power of 1800kW (1600kW at low speed). After the unit is shut down and the vacuum is destroyed, the circulating water pump only supplies cooling water to the closed water heat exchanger, which consumes a large amount of factory electricity and is not economical. If the circulating water pump is shut down, in order to ensure the normal closed water temperature, the only way to maintain it is to drain and replace water, which wastes a large amount of desalted water and is not economical. Summary of the invention

[0005] In view of the problem in the prior art that after the unit is shut down, a circulating water pump is kept running, which consumes a large amount of factory electricity, the present invention proposes an energy-saving improvement method for the cooling mode of a closed water heat exchanger after the unit is shut down.

[0006] To achieve the above purpose, the technical solution of the present invention is:

[0007] The energy-saving improvement method of the cooling mode of the closed water heat exchanger after the unit is shut down includes the following steps:

[0008] S1. Keep one circulating water pump in the first unit running. When the temperature of the inner cylinder in front of the high and medium pressure cylinder is lower than the preset temperature value, the vacuum is destroyed.

[0009] S2. Shut down the circulating water pump of the first unit and close the outlet butterfly valve of the circulating water pump of the first unit;

[0010] S3. Close the condenser circulating water return butterfly valve;

[0011] S4. The circulating water pump of the second unit is running, and the cooling circulating water is continuously supplied to the closed water heat exchanger through the seawater chlorine dosing pipeline.

[0012] Furthermore, the pipeline between the outlet butterfly valve of the circulating water pump of the first unit and the circulating water return butterfly valve of the condenser is a closed pipeline.

[0013] Furthermore, the closed water heat exchanger is provided with a closed water temperature detection device and a circulating water water side vacuum system. If the closed water temperature rises, the circulating water water side vacuum system is put into operation.

[0014] Furthermore, the flow rate of the circulating water pump of the first unit is greater than that of the second circulating water pump unit.

[0015] Furthermore, the preset temperature value is 300°C.

[0016] Furthermore, the outlet butterfly valve of the circulating water pump of the first unit is a hydraulically controlled check butterfly valve.

[0017] Furthermore, the condenser circulating water return butterfly valve is electrically regulated.

[0018] Furthermore, the condenser is a dual-flow condenser.

[0019] Compared with the existing operation mode, the present invention has the following beneficial effects:

[0020] 1. After the vacuum is broken, the circulating water pump can be stopped and replaced by the circulating water pump of the second unit to continuously provide circulating water through the seawater chlorine dosing pipeline. This saves a lot of plant electricity and does not require equipment modification or additional costs.

[0021] 2. Avoid the closed water draining, water changing and cooling, which wastes a lot of desalted water.

[0022] 3. This improvement plan does not affect the equipment operating conditions after the unit is shut down. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 It is a schematic diagram of the cooling method of a closed water heat exchanger in normal operation of a unit in the prior art;

[0025] Figure 2 It is a schematic diagram of the energy-saving improvement method of the closed water heat exchanger cooling mode after the unit is shut down according to the present invention. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0027] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0028] After the vacuum of the steam turbine is broken, the circulating water pump is shut down as soon as possible, and the temporary machine can provide circulating water as cooling water for the closed water heat exchanger.

[0029] Through the study of existing system equipment, it is found that: Figure 1 As shown, the circulating water pipes of the circulating water pump of the first unit and the circulating water pipe of the circulating water pump of the second unit have a connecting pipe, namely, the seawater chlorine production and dosing pipeline. When the two units are normally running, the two stop gates are opened, and the circulating water of the two units can communicate with each other. The seawater chlorine production and dosing pipeline can be used to provide circulating water as cooling water for the closed water heat exchanger after shutdown.

[0030] The specific implementation plan is:

[0031] In the prior art, after the generator set is shut down, one of the circulating water pumps of the first unit is kept running, and when the temperature of the front inner cylinder of the high and medium pressure cylinder is less than 300° C., the vacuum is destroyed.

[0032] In this embodiment, the currently running water pump of the first unit's circulating water pump is stopped, and the outlet butterfly valve of the currently running water pump of the first unit's circulating water pump is closed, and the outlet butterfly valve is a hydraulically controlled check butterfly valve.

[0033] Through electric regulation, the double-flow condenser circulating water return butterfly valve is quickly closed, and the pipeline from the outlet butterfly valve of the circulating water pump currently running in the first unit to the condenser circulating water return butterfly valve becomes a closed pipeline.

[0034] The circulating water pump of the second unit, which is in temporary operation, continuously provides a small amount of circulating water through the seawater chlorine dosing pipeline to provide cooling for the closed water cooler and maintain normal closed water temperature.

[0035] Strengthen inspection and monitoring. The closed water heat exchanger is equipped with a closed water temperature detection device and a circulating water side vacuum system. If the closed water temperature rises, the circulating water side vacuum system is put into operation to cool the circulating water to ensure that the circulating water is sufficient to provide a cooling effect.

[0036] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An energy-saving improvement method for the cooling mode of a closed water heat exchanger after the unit is shut down, characterized in that: The following steps are involved: S1. Keep one of the circulating water pumps in the first unit running. When the temperature of the inner cylinder in front of the high and medium pressure cylinder is lower than the preset temperature value, the vacuum is destroyed. S2. Shut down the circulating water pump of the first unit and close the outlet butterfly valve of the circulating water pump of the first unit; S3. Close the condenser circulating water return butterfly valve; S4, the circulating water pump of the second unit is running, and the cooling circulating water is continuously provided to the closed water heat exchanger through the seawater chlorine production dosing pipeline; the circulating water pump of the first unit is stopped, and the circulating water pump of the second unit is running.

2. The energy-saving improvement method for the cooling mode of the closed water heat exchanger after the unit is shut down according to claim 1, characterized in that: The pipeline between the outlet butterfly valve of the circulating water pump of the first unit and the circulating water return butterfly valve of the condenser is a closed pipeline.

3. The energy-saving improvement method for the cooling mode of the closed water heat exchanger after the unit is shut down according to claim 1, characterized in that: The closed water heat exchanger is provided with a closed water temperature detection device and a circulating water water side vacuum system. If the closed water temperature rises, the circulating water water side vacuum system is put into operation.

4. The energy-saving improvement method for the cooling mode of a closed water heat exchanger after the unit is shut down according to claim 1, characterized in that: The preset temperature value is 300°C.

5. The energy-saving improvement method for the cooling mode of the closed water heat exchanger after the unit is shut down according to claim 1, characterized in that: The outlet butterfly valve of the circulating water pump of the first unit is a hydraulically controlled check butterfly valve.

6. The energy-saving improvement method for the cooling mode of a closed water heat exchanger after the unit is shut down according to claim 1, characterized in that: The condenser circulating water return butterfly valve is electrically regulated.

7. The energy-saving improvement method for the cooling mode of a closed water heat exchanger after the unit is shut down according to claim 1, characterized in that: The condenser is a double-pass condenser.

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