A marine thermal system with multiple hydrophobic structures

Abstract

The present invention relates to a marine thermal system with a multi-hydrophobic structure, including an auxiliary steam turbine generator set, an auxiliary condenser, and a bypass system. The auxiliary steam turbine generator set has an air ejector drain interface, a main steam drain interface, a main steam valve drain interface, a front cylinder drain interface, and a steam seal supplementary steam drain interface. A multi-stage desuperheating and pressure reducing device is arranged in the bypass system. The first and second stage desuperheating and pressure reducing devices are both composed of the form of "pressure reducing valve + desuperheater". The pressure reduction ratios of the desuperheating and pressure reducing devices at all levels match the drain pressure, that is, the steam pressure after desuperheating and pressure reducing at all levels is less than the drain pressure in the pipeline section into which it is discharged. The present invention optimizes the complex system in which steam drains of different pressure levels of the marine steam turbine generator set need to be led to various pressure vessels, effectively reducing the space occupied by the equipment. At the same time, introducing high-temperature drains into the condenser is beneficial to the thermal deaeration of condensate, improving the economy of the entire circulation system; and can quickly and stably control the steam network pressure, which is beneficial to the safety of the steam system.

Description

Technical Field

[0001] The present invention relates to a marine auxiliary steam turbine, and in particular to a marine thermal system with a multi-drainage structure. Background Art

[0002] In marine conditions, the steam entering the auxiliary steam turbine generator set contains a large amount of moisture. In addition to the drain interface of the air ejector, there is a need for multiple drain interfaces such as main steam drain, main steam valve drain, front cylinder drain, and steam seal supplementary steam drain in the unit; the conventional marine thermal system layout requires draining the drains of different pressure levels to various pressure vessels, and the layout of the entire system and pipelines is relatively complex and occupies a large space. And there is currently no such marine thermal system with a multi-drainage structure in China. Therefore, considering the sudden load addition and removal conditions of the marine steam turbine generator set and the requirements of multiple drain interfaces such as main steam valve drain, front cylinder drain, steam seal supplementary steam drain, and air ejector drain in the unit; according to the conventional marine system layout, it needs to be drained to different pressure vessels such as the deaerator, condenser, or each dirty condensate tank, and the layout of the entire system and pipelines is relatively complex and occupies a large space. There is a need to develop a multi-drainage structure thermal system suitable for marine steam turbine generator sets. Summary of the Invention

[0003] The present invention aims to propose a marine thermal system with a multi-drainage structure suitable for marine steam turbine generator sets, and utilize the bypass exhaust desuperheating and pressure-reducing exhaust steam interface of the auxiliary condenser to construct a new multi-drainage structure thermal system, optimize the original complex drainage system, reduce the occupied space, facilitate the condensate recovery of the system, improve the economy of the entire circulation system, and can be extended to a system integrating more marine steam drain interfaces such as drain water evaporator drain, seawater evaporator drain, and feed water heater drain.

[0004] To achieve the above object, the technical solution of the present invention is: a marine thermal system with a multi-drainage structure, including an auxiliary steam turbine generator set, an auxiliary condenser, and a bypass exhaust system. The auxiliary steam turbine generator set has an air ejector drain interface, a main steam drain interface, a main steam valve drain interface, a front cylinder drain interface, and a steam seal supplementary steam drain interface. A multi-stage desuperheating and pressure-reducing device is provided in the bypass exhaust system. The first-stage and second-stage desuperheating and pressure-reducing devices are both composed of the form of "pressure reducing valve + desuperheater", and the pressure reduction ratios of each stage of the desuperheating and pressure-reducing device match the drain pressure, that is, the steam pressure after desuperheating and pressure reduction at each stage is less than the pressure of the drain discharged into this section of the pipeline.

[0005] Further, the high-pressure drains of the main steam and main steam valve in the marine thermal system respectively pass through the steam trap and then enter the rear end of the first-stage desuperheating and pressure-reducing device; the medium-pressure drain of the front cylinder passes through the steam trap and enters the rear end of the second-stage desuperheating and pressure-reducing device; the low-pressure drains of the air ejector and steam seal supplementary steam pass through the steam trap and enter the rear end of the third-stage pressure reducing valve.

[0006] Furthermore, a baffle type steam-water separator is arranged in the steam turbine inlet pipeline of the marine thermal system, and an inverted bucket type steam trap is arranged at the drain outlet of the baffle type steam-water separator.

[0007] Furthermore, the main steam valve drain interface, the front cylinder drain interface, and the steam seal supplementary steam drain interface are selected with a bimetallic steam trap or an inverted bucket type steam trap with check function and good anti-water hammer performance.

[0008] Furthermore, a float type steam trap is adopted for the air extractor drain interface, and a thermostatic air evacuation device is included in the float steam trap, which is easy for vacuum pumping before starting the machine.

[0009] Furthermore, secondary low-pressure drain interfaces are respectively arranged at the pipeline elbows or ends of the first and second desuperheating and pressure reducing pipelines to relieve the erosion effect of the long-term water hammer action of the drain water and desuperheating water discharged into the desuperheating and pressure reducing pipeline on the pipeline. The secondary low-pressure drain interface is led into the rear end of the third-stage pressure reducing valve through a steam trap.

[0010] Furthermore, the steam trap is selected as a lever float type steam trap that can exhaust air statically.

[0011] Furthermore, the auxiliary condenser is provided with a bypass exhaust steam interface, and a spray desuperheating device is arranged at the bypass exhaust steam interface to further reduce the enthalpy value of the exhaust steam entering the condenser.

[0012] Furthermore, each pressure reducing valve in the marine thermal system is selected as a hydraulic valve or a pneumatic valve with sensitive regulation to quickly match the steam pressure when the bypass exhaust steam flow changes.

[0013] The beneficial effects of the present invention are as follows:

[0014] A marine thermal system with a multi-drain structure of the present invention, on the basis of referring to the conventional marine drain system, breaks through the conventional thinking, reasonably utilizes the bypass multi-stage desuperheating and pressure reducing system to match the drain interface requirements of steam turbine generator sets with different pressure levels, optimizes the original complex drain system, reduces the occupied space, is beneficial to the condensate recovery of the system, improves the economy of the entire circulation system, and can be extended to a system integrating more marine steam drain interfaces.

[0015] This system optimizes the complex system in which steam drains with different pressure levels of marine steam turbine generator sets need to be led to each pressure vessel, effectively reduces the space occupied by the equipment. At the same time, introducing high-temperature drain water into the condenser is beneficial to the thermal deaeration of condensate, improving the economy of the entire circulation system; in addition, this system can quickly and stably control the steam pipe network pressure, which is beneficial to the safety of the steam system. Description of the Drawings

[0016] Figure 1 It is a marine thermal system diagram with a multi-drain structure of the present invention;

[0017] Figure 2 It is a schematic diagram of a baffle type steam-water separator;

[0018] Figure 3 It is a schematic diagram of an inverted bucket type steam trap;

[0019] Figure 4 It is a schematic diagram of a bimetallic strip type steam trap;

[0020] Figure 5 It is a schematic diagram of a float type steam trap. Specific embodiments

[0021] The present invention will be specifically described below through embodiments. However, it is necessary to point out here that the embodiments are only used to further illustrate the present invention and cannot be understood as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above content of the present invention without creative labor for specific implementation.

[0022] The present embodiment relates to a thermal system with a multi-steam trap structure under marine conditions. The system diagram is as shown in the appendix Figure 1 After a baffle type steam-water separator 1 is arranged in the steam inlet pipeline of the auxiliary steam turbine generator set, the steam enters the main steam valve 17 of the steam turbine 16. The condensate of the baffle type steam-water separator 1 passes through an inverted bucket type steam trap 2, and the condensate of the main steam valve 17 passes through a bimetallic strip type steam trap 5 and then enters the rear end of the first stage pressure reducing valve 3 and the desuperheater 4. The condensate of the front cylinder passes through a bimetallic strip type steam trap 6 and enters the rear end of the second stage pressure reducing valve 7 and the desuperheater 8. The condensate of the steam seal make-up steam passes through a metallic strip type steam trap 10, and the condensate of the air extractor passes through float type steam traps 14 and 15 and then enters the third stage pressure reducing valve 9. To alleviate the erosion effect of the long-term water hammer action of the condensate and desuperheating water discharged into the desuperheating and pressure reducing pipeline on the pipeline, secondary low-pressure condensate interfaces are respectively arranged at the pipeline elbows or ends in the first and second desuperheating and pressure reducing pipelines. The secondary low-pressure condensate interfaces pass through float type steam traps 11 and 12 and enter the rear end of the third stage pressure reducing valve 9. A water spraying device 13 is arranged in front of the condenser side discharge interface to further reduce the enthalpy value of the exhaust steam.

[0023] When implementing this marine thermal system with multiple hydrophobic structures, appropriate types of steam traps need to be selected for each hydrophobic interface according to requirements such as pressure grade, hydrophobic flow rate, continuous / intermittent drainage, and check valves. Manual stop valves are installed before and after each steam trap for convenient maintenance and isolation. The hydrophobic discharges at all levels are drained into the bypass desuperheating and pressure-reducing pipeline. The inlet and outlet of each section of the desuperheating and pressure-reducing pipeline need to show a downward trend to ensure a certain height difference, preventing secondary hydrophobic blockage caused by a small pressure difference in the pipeline during the small-flow bypass drainage condition. Considering that there is a certain air leakage in the hydrophobic discharges at all levels, key factors affecting the vacuum such as the extraction volume of the air extractor 18 and the heat transfer area of the condenser 19 need to be provided with a margin to prevent the back pressure of the condenser from rising due to the multiple hydrophobic structures of this system. When the bypass exhaust steam flow rate changes, to quickly match the steam pressure, each pressure-reducing valve needs to select a hydraulic valve or pneumatic valve with sensitive adjustment. Considering that flashing may occur when the hydrophobic discharges at all levels enter the desuperheating and pressure-reducing pipeline, appropriate safety margins need to be considered for the pipeline wall thickness and the flow velocity inside the pipeline.

[0024] Different from the conventional marine integrated desuperheating and pressure-reducing valve or the bypass system that reduces pressure first and then reduces temperature, this system is provided with multiple desuperheating and pressure-reducing devices in the bypass system. The first and second stage desuperheating and pressure-reducing devices are both composed of the form of "pressure-reducing valve + desuperheater". The pressure reduction ratio of each stage of the desuperheating and pressure-reducing device needs to match the hydrophobic pressure, that is, the steam pressure after desuperheating and pressure reduction at each stage is less than the pressure of the hydrophobic discharged into this section of the pipeline. As shown in Figure 1 the figure, according to the pressure matching principle, high-pressure hydrophobic such as main steam hydrophobic and main steam valve hydrophobic are respectively passed through the steam trap and then into the rear end of the first stage desuperheating and pressure-reducing device; medium-pressure hydrophobic such as front cylinder hydrophobic is passed through the steam trap and into the rear end of the second stage desuperheating and pressure-reducing device; low-pressure hydrophobic such as air extractor hydrophobic and steam seal supplementary steam hydrophobic is passed through the steam trap and into the rear end of the third stage pressure-reducing valve.

[0025] When warming up the pipeline during startup, the main steam pipeline contains a large amount of water. Therefore, a baffle type steam-water separator suitable for higher velocity steam is installed in the pipeline at the inlet of the steam turbine. See Figure 2 the figure. A bucket-type steam trap with a large flow-through capacity is installed at the drainage port of this baffle type steam-water separator. See Figure 3 the figure; for high, medium, and low-pressure hydrophobic interfaces with small hydrophobic discharge amounts such as the main steam valve, front cylinder, and steam seal supplementary steam of the steam turbine, a bimetallic steam trap with check function and good water hammer resistance is selected. See Figure 4 the figure, or a bucket-type steam trap. Among them, the bimetallic steam trap is small in size, convenient for disassembly and cleaning, and needs to be adjusted regularly. The air extractor hydrophobic is low-pressure hydrophobic. Considering the need for continuous drainage during operation, a float type steam trap is suitable. See Figure 5 the figure. This float steam trap contains a thermostatic exhaust device, which is easy for vacuum extraction before startup.

[0026] To alleviate the erosion effect of the long-term water hammer of the drain water and desuperheating water discharged into the desuperheating and pressure-reducing pipeline on the pipeline, except for the last-stage desuperheating and pressure-reducing pipeline, secondary drain water interfaces shall be set at the pipeline elbows or the ends of other desuperheating and pressure-reducing pipelines respectively. The secondary low-pressure drain water interface is led into the back end of the third-stage pressure-reducing valve through a steam trap, and the steam trap shall be a lever float type steam trap that can exhaust statically. A spray desuperheating device shall be set at the side discharge interface of the condenser to further reduce the enthalpy value of the exhaust steam entering the condenser; when the flow rate of the side discharge exhaust steam changes, in order to quickly match the steam pressure, each pressure-reducing valve shall be a hydraulic valve or a pneumatic valve with sensitive regulation.

[0027] This system optimizes the complex system in which the steam drains of different pressure levels of the marine steam turbine generator set need to be led to each pressure vessel, effectively reducing the space occupied by the equipment. At the same time, the high-temperature drain water entering the condenser is beneficial to the thermal deaeration of the condensate, improving the economy of the entire circulation system; in addition, this system can quickly and stably control the steam pipe network pressure, which is beneficial to the safety of the steam system.

Claims

1. A marine thermal system with a multi-hydrophobic structure, including an auxiliary steam turbine generator set, an auxiliary condenser, and a bypass system. The auxiliary steam turbine generator set has an air ejector drain interface, a main steam drain interface, a main steam valve drain interface, a front cylinder drain interface, and a steam seal supplementary steam drain interface. Characterized in that: A multi-stage desuperheating and pressure-reducing device is provided in the bypass system. The first and second stage desuperheating and pressure-reducing devices are both composed of the form of "pressure reducing valve + desuperheater". The pressure reduction ratio of each stage of desuperheating and pressure-reducing device matches the drain pressure, that is, the steam pressure after desuperheating and pressure-reducing at each stage is less than the pressure of the drain water discharged into this section of the pipeline; the main steam and the high-pressure drain of the main steam valve in the marine thermal system respectively pass through a steam trap and then enter the rear end of the first stage desuperheating and pressure-reducing device; the medium-pressure drain of the front cylinder passes through a steam trap and enters the rear end of the second stage desuperheating and pressure-reducing device; the low-pressure drains of the air ejector and the steam seal supplementary steam pass through a steam trap and enter the rear end of the third stage desuperheating and pressure-reducing device; secondary low-pressure drain interfaces are respectively provided at the pipeline elbows or ends in the pipelines of the first and second stage desuperheating and pressure-reducing devices to relieve the erosion effect of the long-term water hammer action of the drain water and desuperheating water discharged into the desuperheating and pressure-reducing pipeline on the pipeline. The secondary low-pressure drain interfaces pass through a steam trap and enter the rear end of the third stage desuperheating and pressure-reducing device; the auxiliary condenser is provided with a bypass exhaust steam interface, and a spray desuperheating device is provided at the bypass exhaust steam interface to further reduce the enthalpy value of the exhaust steam entering the condenser.

2. The marine thermal system with a multi-hydrophobic structure according to claim 1, Characterized in that: A baffle type steam-water separator is provided in the steam turbine inlet pipeline of the marine thermal system, and an inverted bucket type steam trap is provided at the drain outlet of the baffle type steam-water separator.

3. The marine thermal system with a multi-hydrophobic structure according to claim 1, Characterized in that: The main steam valve drain interface, the front cylinder drain interface, and the steam seal supplementary steam drain interface are selected as bimetallic sheet type steam traps or inverted bucket type steam traps with check function and good anti-water hammer performance.

4. The marine thermal system with a multi-hydrophobic structure according to claim 1, Characterized in that: The air ejector drain interface adopts a float type steam trap, and the float type steam trap contains a thermostatic exhaust device, which is easy for vacuum pumping before starting the machine.

5. The marine thermal system with a multi-hydrophobic structure according to claim 1, Characterized in that: The steam trap connecting the secondary low-pressure drain interface and the rear end of the third stage desuperheating and pressure-reducing device is selected as a lever float type steam trap that can exhaust statically.

6. The marine thermal system with a multi-hydrophobic structure according to any one of claims 1-5, Characterized in that: Each pressure reducing valve in the marine thermal system is selected as a hydraulic valve or a pneumatic valve with sensitive adjustment, which is used to quickly match the steam pressure when the bypass exhaust steam flow rate changes.

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