A system and method for recovering excess pressure and excess heat in a back pressure heating unit

Abstract

The present invention provides a system and method for recovering excess pressure and excess heat in a back-pressure heating unit, which can reduce the loss of water, heat and pressure energy, increase the heating capacity of the back-pressure heating unit, and eliminate the phenomenon of "white smoke". The present invention includes a back-pressure steam turbine, a deaerator, a drain tank, a drain expansion tank, a periodic sewage expansion tank, valves No. 1 to No. 7, a steam jet pump, a main pipeline and a bypass pipeline. During normal operation, valve No. 3 and valve No. 4 are closed, and the remaining valves are opened; the exhaust steam of the back-pressure steam turbine is sent to the steam jet pump as working steam, so that after the steam jet pump extracts the exhaust steam of the periodic sewage expansion tank, the drain expansion tank, and the drain tank, the pressure is reduced to medium-pressure steam that can be used by the deaerator, and the medium-pressure steam enters the deaerator; if the steam jet pump fails, the bypass valve No. 3 and valve No. 4 are opened, and the valve No. 1 and valve No. 2 are closed, and the system can continue to work to ensure the continuous operation of the system.

Description

Technical Field

[0001] The invention relates to a system and method for recovering excess pressure and excess heat in a back-pressure heating unit. Background Art

[0002] 1. In traditional back-pressure heating units, the back-pressure exhaust steam pressure for external network heating often cannot match the heating steam pressure of the deaerator. In order to meet the requirements of external network heating, the heating steam of the deaerator often needs to be throttled to reduce pressure and temperature, which will inevitably lead to a waste of pressure energy due to throttling and pressure reduction.

[0003] 2. In traditional back-pressure heating units, it is necessary to install expansion devices such as regular sewage expansion tanks, drain expansion tanks, and drain tanks. The exhaust steam of these devices often goes directly to the atmosphere, which often forms the phenomenon of "white smoke". This phenomenon not only easily affects the visual effect of the entire thermal power plant, but also increases the loss of water and heat in the thermal system of the thermal power plant. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a system and method for recovering excess pressure and excess heat in a back-pressure heating unit with a rational structural design, which can reduce the loss of water, heat and pressure energy, increase the heating capacity of the back-pressure heating unit, and eliminate the phenomenon of "white smoke".

[0005] The technical solution adopted by the present invention to solve the above-mentioned problem is: a system for recovering excess pressure and excess heat in a back-pressure heating unit, comprising a back-pressure steam turbine, a deaerator, a drain tank, a drain expansion tank and a periodic sewage expansion tank; characterized in that: it also includes valve No. 1, valve No. 2, valve No. 3, valve No. 4, valve No. 5, valve No. 6, valve No. 7, a steam jet pump, a main line and a bypass pipeline; the exhaust port of the back-pressure steam turbine is connected to the deaerator through the main line, and valve No. 1, steam jet pump and valve No. 2 are installed on the main line in sequence; the bypass pipeline is connected in parallel with the main line, and valve No. 3 and valve No. 4 are installed on the bypass pipeline in sequence; the steam extraction port of the steam jet pump is connected to the periodic sewage expansion tank through a pipeline, and valve No. 5 is installed on the pipeline; the steam extraction port of the steam jet pump is connected to the drain expansion tank through a pipeline, and valve No. 6 is installed on the pipeline; the steam extraction port of the steam jet pump is connected to the drain tank through a pipeline, and valve No. 7 is installed on the pipeline.

[0006] The invention also comprises an external network heat-using device, which is connected to the exhaust port of the back-pressure steam turbine.

[0007] The present invention also comprises a regulating valve, and the third valve, the regulating valve and the fourth valve are sequentially installed on the bypass pipeline.

[0008] The valve No. 1, valve No. 2, valve No. 3 and valve No. 4 described in the present invention are all manual gate valves, and the valve No. 5, valve No. 6 and valve No. 7 are all electric gate valves.

[0009] A method for recovering excess pressure and waste heat in a back-pressure heating unit, characterized in that: the above-mentioned recovery system is used, and the steps are as follows: during normal operation, close valve No. 3 and valve No. 4, open valve No. 1 and valve No. 2, and open valve No. 5, valve No. 6 and valve No. 7 at the same time; the exhaust steam of the back-pressure steam turbine is sent to the steam jet pump as working steam, so that after the steam jet pump extracts the exhaust steam of the periodic sewage expansion tank, the drain expansion tank, and the drain tank, the pressure is reduced to medium-pressure steam that can be used by the deaerator, and the medium-pressure steam enters the deaerator; if the steam jet pump fails during operation, open the bypass valve No. 3 and valve No. 4, close valve No. 1 and valve No. 2, and the system can continue to work to ensure the continuous operation of the system.

[0010] Compared with the prior art, the present invention has the following advantages and effects:

[0011] 1. Recover the excess pressure loss caused by throttling of deaeration heating steam and increase the heating capacity of the back pressure heating unit.

[0012] 2. Reduce the loss of water and heat in the thermal system, eliminate the phenomenon of "white smoke", and beautify the production environment of the thermal power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic structural diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0014] The present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0015] See also Figure 1 The present invention includes valve No. 1 1, valve No. 2 2, valve No. 3 3, valve No. 4 4, valve No. 5 5, valve No. 6 6, valve No. 7 7, back pressure steam turbine 8, external network heat device 9, steam jet pump 10, regulating valve 11, deaerator 12, drain tank 13, drain expansion tank 14, periodic sewage expansion tank 15, main pipeline 16 and bypass pipeline 17.

[0016] The exhaust port of the back pressure steam turbine 8 is connected to the deaerator 12 through the main pipeline. The main pipeline 16 is sequentially installed with a valve No. 1, a steam jet pump 10, and a valve No. 2 2. The inlet and outlet of the steam jet pump 10 are both connected to the main pipeline 16.

[0017] The bypass pipeline 17 is connected in parallel with the main pipeline 16 , and a No. 3 valve 3 , a regulating valve 11 , and a No. 4 valve 4 are sequentially installed on the bypass pipeline 17 .

[0018] The steam extraction port of the steam jet pump 10 is connected to the periodic blowdown expansion tank 15 through a pipeline, and a No. 5 valve 5 is installed on the pipeline. The steam extraction port of the steam jet pump 10 is connected to the drain expansion tank 14 through a pipeline, and a No. 6 valve 6 is installed on the pipeline. The steam extraction port of the steam jet pump 10 is connected to the drain tank 13 through a pipeline, and a No. 7 valve 7 is installed on the pipeline.

[0019] Valve No. 1 1, valve No. 2 2, valve No. 3 3, and valve No. 4 4 are all manual gate valves, and valve No. 5 5, valve No. 6 6, and valve No. 7 7 are all electric gate valves.

[0020] The external network heat device 9 is connected to the exhaust port of the back pressure steam turbine 8.

[0021] A method for recovering excess pressure and excess heat in a back pressure heating unit is implemented using the above recovery system, and the steps are as follows:

[0022] During normal operation, close valve No. 3 and valve No. 4, open valve No. 1 and valve No. 2, and open valve No. 5, valve No. 6, and valve No. 7 at the same time. The exhaust steam of the back pressure steam turbine 8 is high-pressure steam, which is sent to the steam jet pump 10 as working steam, so that the steam jet pump 10 extracts the exhaust steam of the periodic sewage expansion tank 15, the drain expansion tank 14, and the drain tank 13, and the pressure is reduced to medium-pressure steam that can be used by the deaerator, and the medium-pressure steam enters the deaerator 12. In this way, the working fluid and heat of the exhaust steam of the periodic sewage expansion tank 15, the drain expansion tank 14, and the drain tank 13 can be recovered, and the high-pressure steam consumption of deoxidation heating can be reduced, and more heat can be supplied to the external network heat-using device.

[0023] For example, if the steam jet pump 10 fails during operation, the bypass valve No. 3 and valve No. 4 are opened, and the valve No. 1 and valve No. 2 are closed, and the system can continue to work to ensure the continuous operation of the thermal system.

[0024] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is only an example of the structure of the present invention. All equivalent changes or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. Technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A system for recovering excess pressure and excess heat in a back-pressure heating unit, comprising a back-pressure steam turbine, a deaerator, a drain tank, a drain expansion tank and a periodic sewage expansion tank; characterized in that: It also includes valve No. 1, valve No. 2, valve No. 3, valve No. 4, valve No. 5, valve No. 6, valve No. 7, a steam jet pump, a main line and a bypass pipeline; the exhaust port of the back-pressure steam turbine is connected to the deaerator through the main line, and valve No. 1, a steam jet pump and valve No. 2 are installed on the main line in sequence; the bypass pipeline is connected in parallel with the main line, and valve No. 3 and valve No. 4 are installed on the bypass pipeline in sequence; the steam extraction port of the steam jet pump is connected to the periodic sewage expansion tank through the pipeline, and valve No. 5 is installed on the pipeline; the steam extraction port of the steam jet pump is connected to the drain expansion tank through the pipeline, and valve No. 6 is installed on the pipeline; the steam extraction port of the steam jet pump is connected to the drain tank through the pipeline, and valve No. 7 is installed on the pipeline.

2. The system for recovering excess pressure and excess heat in a back pressure heating unit according to claim 1, characterized in that: It also includes an external network heat-using device, which is connected to the exhaust port of the back-pressure steam turbine.

3. The system for recovering excess pressure and excess heat in a back pressure heating unit according to claim 1, characterized in that: It also includes a regulating valve, and valve No. 3, regulating valve and valve No. 4 are installed on the bypass pipeline in sequence.

4. The system for recovering excess pressure and excess heat in a back pressure heating unit according to claim 1, characterized in that: The valve No. 1, valve No. 2, valve No. 3 and valve No. 4 are all manual gate valves, and the valve No. 5, valve No. 6 and valve No. 7 are all electric gate valves.

5. A method for recovering excess pressure and excess heat in a back pressure heating unit, characterized in that: The recovery system described in any one of claims 1 to 4 is used, and the steps are as follows: during normal operation, close valve No. 3 and valve No. 4, open valve No. 1 and valve No. 2, and open valve No. 5, valve No. 6 and valve No. 7 at the same time; the exhaust steam of the back-pressure steam turbine is sent to the steam jet pump as working steam, so that after the steam jet pump extracts the exhaust steam of the periodic sewage expansion tank, the drain expansion tank, and the drain tank, the pressure is reduced to medium-pressure steam that can be used by the deaerator, and the medium-pressure steam enters the deaerator; if the steam jet pump fails during operation, open the bypass valve No. 3 and valve No. 4, close valve No. 1 and valve No. 2, and the system can continue to work to ensure continuous operation of the system.

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