Steam supplementing and regenerative system of steam turbine

Abstract

The utility model discloses a steam turbine steam supplementing and heat regenerating system which comprises a multi-stage high-pressure heater and a multi-stage low-pressure heater which are connected between a boiler and a steam turbine, a deaerator is connected between the multi-stage high-pressure heater and the multi-stage low-pressure heater, and the boiler is connected with a high-pressure cylinder of the steam turbine through a main steam pipeline. The multi-stage high-pressure heater comprises a No.0 high-pressure heater additionally arranged between the No.1 high-pressure heater and the boiler, a steam extraction opening of the No.0 high-pressure heater is arranged on a steam supplementing pipeline, the steam supplementing pipeline is connected between the main steam pipeline and the high-pressure cylinder, a gulp valve is installed on the steam supplementing pipeline, and a steam extraction opening of the No.0 high-pressure heater is located between the gulp valve and the high-pressure cylinder. The requirement for improving the final feed water temperature by partial load is met, and the economical efficiency of the partial load of the unit is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of steam turbine power generation, in particular to a steam turbine heat recovery system. Background Art

[0002] With the continuous development and popularization of new energy power generation technology, the power generation load of renewable energy such as wind power and photovoltaic power generation continues to increase, and its consumption problem has gradually become prominent and increasingly severe. In order to effectively respond to this challenge, it is necessary to start from multiple aspects, including improving the peak load regulation capacity of power sources, adjusting the layout of wind power, strengthening grid mutual assistance and load-side management. These measures will help to better integrate and utilize renewable energy and achieve sustainable energy development.

[0003] In the competitive electricity market, thermal power units need to flexibly adjust their output according to price fluctuations in the market. At the same time, under the new electricity supply and demand environment, the utilization hours of thermal power are expected to remain at a low level for a long time, and the role of some thermal power base load power sources will change.

[0004] Operational flexibility is the key to coal-fired power units adapting to the demand for new energy consumption. In order to consume more fluctuating renewable energy, existing coal-fired power units, including pure condensing and thermal power, need to improve their peak regulation, ramping capability, and start-stop speed to flexibly participate in the electricity market. This requires us to upgrade and transform the existing coal-fired power units to improve their operational flexibility.

[0005] However, the existing coal-fired units in deep peak-shaving operation mode operate at low load, deviate far from the designed high efficiency point, and their thermal efficiency shows a rapid downward trend. They are unable to give full play to the advantages of the high efficiency of supercritical units, affecting the economy of the units under partial load. Utility Model Content

[0006] The utility model aims to provide a steam turbine supplementary steam heat recovery system, which can solve the problem that when existing coal-fired units are operated in peak-shaving mode to adapt to the demand for new energy consumption, they cannot give full play to the high efficiency advantages of supercritical units and have low economy under partial load.

[0007] In order to solve the above problems, the technical solution adopted by the utility model is: the steam turbine supplementary steam heat recovery system includes a multi-stage high-pressure heater and a multi-stage low-pressure heater connected between the boiler and the steam turbine, a deaerator is connected between the multi-stage high-pressure heater and the multi-stage low-pressure heater, the boiler is connected to the high-pressure cylinder of the steam turbine through a main steam pipe, the multi-stage high-pressure heater includes a No. 0 high-pressure heater added between the No. 1 high-pressure heater and the boiler, the steam extraction port of the No. 0 high-pressure heater is arranged on the supplementary steam pipe, the supplementary steam pipe is connected between the main steam pipe and the high-pressure cylinder, an air supply valve is installed on the supplementary steam pipe, and the steam extraction port of the No. 0 high-pressure heater is located between the air supply valve and the high-pressure cylinder.

[0008] In the technical scheme of the above-mentioned steam turbine supplementary steam heat recovery system, a more specific technical scheme can also be: a condenser, a condensate pump and a shaft seal heater are connected in sequence between the exhaust port of the low-pressure cylinder of the steam turbine and the multi-stage low-pressure heater, the shaft seal heater is connected to the condenser through a return water pipe, and the air leakage of the self-sealing system is respectively connected to the last-stage low-pressure heater of the multi-stage low-pressure heater, the shaft seal heater and the hot well of the condenser.

[0009] Furthermore, the multi-stage high-pressure heater also includes a high-pressure heater No. 2 and a high-pressure heater No. 3. The drain outlets of the high-pressure heater No. 0 and the high-pressure heater No. 1 are connected in parallel and then connected to the drain inlet of the high-pressure heater No. 2. The drain outlet of the high-pressure heater No. 2 is connected to the drain inlet of the high-pressure heater No. 3, and the drain outlet of the high-pressure heater No. 3 is connected to the deaerator.

[0010] Furthermore, the multi-stage low-pressure heater comprises low-pressure heater No. 5, low-pressure heater No. 6, low-pressure heater No. 7 and low-pressure heater No. 8 which are connected in series in sequence, and the drain of the multi-stage low-pressure heater is connected by gravity step by step.

[0011] Furthermore, a regulating valve and a check valve are installed on the No. 0 high-pressure heater steam extraction pipeline.

[0012] Furthermore, the intermediate pressure cylinder of the steam turbine is a double-flow intermediate pressure cylinder, and the low pressure cylinder is a double-flow low pressure cylinder.

[0013] Due to the adoption of the above technical solution, the utility model has the following beneficial effects compared with the prior art:

[0014] 1. By adding a No. 0 high-pressure heater and connecting a supplementary steam pipeline with a valve between the high-pressure cylinder and the main steam pipeline, the steam extraction port of the No. 0 high-pressure heater is set on the supplementary steam pipeline, which can more effectively utilize thermal energy, improve thermal efficiency, and improve the stable combustion characteristics of the boiler under low load; meet the requirements of increasing the final feed water temperature under partial load, and improve the partial load economy of the unit; when the unit is operating under variable load, the setting of the additional No. 0 high-pressure heater helps to maintain the stability of the flue gas temperature at the economizer outlet, and also helps the denitrification equipment to maintain efficient operation in a wide load range, and slow down the aging rate of the catalyst; this can not only ensure the safety and reliability of the operation of the denitrification equipment, but also help to improve the environmental protection performance of the entire unit, and achieve a win-win situation of economic and environmental benefits; from the perspective of flow, the steam extraction port of the No. 0 high-pressure heater is shared with the supplementary steam pipeline, and there is no need to open a hole on the high-pressure cylinder to increase the steam extraction port. This design not only simplifies the system structure, but also ensures the flow efficiency of the high-pressure cylinder and improves the overall performance of the unit; in addition, it also simplifies the pipeline design and layout, saving the construction period and subsequent inspection and maintenance costs.

[0015] 2. By rationally handling and optimizing the steam leakage path of the self-sealing system SSR, steam can be effectively prevented from leaking from the end steam seal to the machine room and oil system, thereby avoiding environmental pollution and damage to the oil quality; at the same time, using the heat of the steam leakage to heat the condensate can not only reduce steam leakage and heat loss, but also help to improve the thermal efficiency of the entire unit. The recovery and reuse of this heat is of great significance to reducing energy consumption and lowering operating costs.

[0016] 3. The number and connection design of the multi-stage high-pressure heaters ensure that the high-pressure heater drainage is properly handled, fully utilizing the thermal energy of the hot water discharged from the high-pressure heater, improving the thermal efficiency of the entire system, and ensuring the safety and stability of the system operation.

[0017] 4. Set up four low-pressure heaters in series and use step-by-step drainage to achieve gradual accumulation and transfer of thermal energy.

[0018] 5. Regulating valves, check valves, etc. are arranged on the steam extraction pipeline of the No. 0 high-pressure heater to ensure the safety of steam extraction. The steam extraction volume of the No. 0 high-pressure heater is adjusted and controlled by the regulating valve on the steam extraction pipeline to ensure the economical operation of the No. 0 high-pressure heater.

[0019] 6. The medium-pressure cylinder and low-pressure cylinder adopt a double-flow structure, which can effectively improve the thermal efficiency, operating stability and circulation efficiency of the turbine. It has a certain flexibility and can adapt to different operating conditions and requirements. Whether it is under high load or low load operation, the double-flow cylinder can maintain good performance, making the unit have better adaptability and stability when operating under variable conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1This is a schematic diagram of the steam turbine supplementary steam heat recovery system.

[0021] Figure 2 It is a schematic diagram of the supplementary steam pipeline and the No. 0 high-pressure heater steam extraction pipeline.

[0022] Figure numerals: 1. boiler; 2. high-pressure cylinder; 3. medium-pressure cylinder; 4. low-pressure cylinder; 5. generator; 6. condenser; 7. condensate pump; 8. shaft seal heater; 9. low-pressure heater No. 8; 10. low-pressure heater No. 7; 11. low-pressure heater No. 6; 12. low-pressure heater No. 5; 13. deaerator; 14. feed water pump; 15. high-pressure heater No. 3; 16. high-pressure heater No. 2; 17. high-pressure heater No. 1; 18. high-pressure heater No. 0; 18-1, steam extraction port; 19. steam supply valve. DETAILED DESCRIPTION

[0023] The utility model is further described in detail below in conjunction with the accompanying drawings:

[0024] Figure 1 and Figure 2 The steam turbine supplementary steam reheating system shown includes a multi-stage high-pressure heater connected between the boiler 1 and the steam turbine, a multi-stage low-pressure heater, a deaerator 13 and a feedwater pump 14. In addition to the No. 1 high-pressure heater 17, the No. 2 high-pressure heater 16 and the No. 3 high-pressure heater 15, the multi-stage high-pressure heater of this embodiment also adds a No. 0 high-pressure heater 18 between the No. 1 high-pressure heater 17 and the boiler 1. The drain outlets of the No. 0 high-pressure heater 18 and the No. 1 high-pressure heater 17 are connected in parallel and then connected to the drain inlet of the No. 2 high-pressure heater 16. The drain outlet of the No. 2 high-pressure heater 16 is connected to the drain inlet of the No. 3 high-pressure heater 15, and the drain outlet of the No. 3 high-pressure heater 15 is connected to the deaerator 13. The multi-stage low-pressure heater includes the No. 5 low-pressure heater 12, the No. 6 low-pressure heater 11, the No. 7 low-pressure heater 10 and the No. 8 low-pressure heater 9 connected in series in sequence, and the drains of the multi-stage low-pressure heaters are connected step by step by gravity. The water outlet of the No. 5 low-pressure heater 12 is connected to the water inlet of the deaerator 13 , and the water outlet of the deaerator 13 is connected to the water inlet of the No. 3 high-pressure heater 15 through a water feed pump 14 .

[0025] The steam turbine of the supplementary steam reheating system comprises a high-pressure cylinder 2, an intermediate-pressure cylinder 3, and a low-pressure cylinder 4 which are coaxially connected in sequence, and a generator 5 is connected to one end of the rotating shaft close to the low-pressure cylinder 4. The high-pressure cylinder 2 of this embodiment is a single-flow high-pressure cylinder, the intermediate-pressure cylinder 3 is a double-flow intermediate-pressure cylinder, and the low-pressure cylinder 4 is a double-flow low-pressure cylinder. The boiler 1 is connected to the steam inlet of the high-pressure cylinder 2 through the main steam pipeline, the reheater is connected to the steam inlet of the intermediate-pressure cylinder 3 through the reheat steam pipe, and the exhaust port of the intermediate-pressure cylinder 3 is connected to the steam inlet of the low-pressure cylinder 4 through the intermediate-low pressure connecting pipe. The condenser 6, condensate pump 7 and shaft seal heater 8 are connected in sequence between the exhaust port of the low-pressure cylinder 4 and the multi-stage low-pressure heater. The exhaust port of the low-pressure cylinder 4 is connected to the steam inlet of the condenser 6 through the low-pressure exhaust pipe, and the water outlet of the condenser 6 is connected to the inlet of the condensate pump 7. The outlet of the condensate pump 7 is connected to the inlet of the shaft seal heater 8, providing condensate for the shaft seal heater 8. The shaft seal heater 8 is also connected to the condenser 6 through a return water pipe. The condensate treated by the shaft seal heater 8 flows to the multi-stage low-pressure heater of the heat recovery system. Preferably, a self-sealing system SSR is also provided, and the leakage of the self-sealing system is respectively connected to the hot well of the No. 8 low-pressure heater 9, the shaft seal heater 8 and the condenser 6.

[0026] The steam supply arrangement of the steam turbine steam supply heat recovery system of this embodiment is as follows: The steam extraction port 18-1 of the No. 0 high-pressure heater 18 is arranged on the steam supply pipeline, see Figure 2 The supplementary steam pipeline is connected between the main steam pipeline and the high-pressure cylinder 2. A supplementary steam valve 19 is installed on the supplementary steam pipeline. The steam extraction port of the No. 0 high-pressure heater 18 is located between the supplementary steam valve 19 and the high-pressure cylinder 2. The supplementary steam pipeline is connected to the corresponding parameter level chamber after the flow, and steam is extracted from the chamber. The steam extraction pipeline of the No. 0 high-pressure heater 18 is equipped with a regulating valve and a check valve to ensure the safety of steam extraction. The steam extraction amount of the No. 0 high-pressure heater 18 is adjusted and controlled by the regulating valve on the steam extraction pipeline to ensure the economic operation of the No. 0 high-pressure heater 18; the high-pressure cylinder 2 is provided with a first-stage steam extraction pipeline and a second-stage steam extraction pipeline, the first-stage steam extraction pipeline is connected to the No. 1 high-pressure heater 17, and the second-stage steam extraction pipeline is connected to the No. 2 high-pressure heater 16; the medium-pressure cylinder 3 is provided with a three-stage steam extraction pipeline and a four-stage steam extraction pipeline, the three-stage steam extraction pipeline is connected to the No. 3 high-pressure heater 15, and the four-stage steam extraction pipeline is connected to the deaerator 13; the low-pressure cylinder 4 is provided with a five-stage steam extraction pipeline, a six-stage steam extraction pipeline, a seven-stage steam extraction pipeline and an eight-stage steam extraction pipeline, the five-stage steam extraction pipeline is connected to the No. 5 low-pressure heater 12, the six-stage steam extraction pipeline is connected to the No. 6 low-pressure heater 11, the seven-stage steam extraction pipeline is connected to the No. 7 low-pressure heater 10, and the eight-stage steam extraction pipeline is connected to the No. 8 low-pressure heater 9.

[0027] During operation, when the unit load is lower than 90%, the high-temperature and high-pressure steam generated by the boiler 1 enters the high-pressure cylinder 2 of the steam turbine to perform work. At this time, the air supply valve 19 is opened to supply steam. At the same time, the No. 0 high-pressure heater 18 extracts steam from the steam supply pipeline. The amount of extracted steam is controlled by a regulating valve to increase the feed water temperature at the water side outlet of the No. 0 high-pressure heater 18. Part of the steam of the high-pressure cylinder 2 enters the No. 1 high-pressure heater 17 and the No. 2 high-pressure heater 16 respectively. After being heated by the No. 0 high-pressure heater 18, the No. 1 high-pressure heater 17 and the No. 2 high-pressure heater 16, the steam provided by the reheating system in the boiler 1 returns to the medium-pressure cylinder 3 through the reheating steam pipeline to perform work. Part of the steam of the medium-pressure cylinder 3 enters the No. 3 high-pressure heater 15 and the deaerator 13 for heating. The steam discharged from the medium-pressure cylinder 3 enters the low-pressure cylinder 4 to perform work. Part of the steam of the low-pressure cylinder 4 enters the No. 5 low-pressure heater 12, the No. 6 low-pressure heater 11, the No. 7 low-pressure heater 10 and the No. 8 low-pressure heater 9 for heating. The step-by-step arrangement of the multi-stage heaters can reduce the heat exchange end difference between steam and feed water. The exhaust steam of the low-pressure cylinder 4 after performing work is condensed by the condenser 6 to form condensate. The condensate pump 7 sends the condensate to the shaft seal heater 8. The shaft seal heater 8 recovers the leakage steam of the shaft seal and uses its heat to heat the condensate, thereby improving the thermal efficiency of the unit. The self-sealing system SSR in the system connects the leaking gas to the No. 8 low-pressure heater 9, the shaft seal heater 8 and the hot well of the condenser 6, which not only realizes the automatic sealing of the system, but also makes full use of the heat energy in the leaking gas, reduces heat loss and improves the thermal efficiency of the unit. Part of the condensed water treated by the shaft seal heater 8 returns to the condenser through the return pipe to form a cycle, and the other part flows to the multi-stage low-pressure heater for step-by-step heating and condensation, and then the oxygen in the steam is removed by the deaerator 13 to ensure the purity of the system, and then it is sent to the No. 3 high-pressure heater 15, the No. 2 high-pressure heater 16, the No. 1 high-pressure heater 17 and the No. 0 high-pressure heater 18 by the feed water pump 14, and finally flows back to the boiler 1 for circulation.

[0028] The steam turbine supplementary steam heat recovery system adds a No. 0 high-pressure heater 18, which increases the partial load feed water temperature of the unit and thus improves the unit's economy. At the same time, the No. 0 high-pressure heater 18 steam extraction pipeline is shared with the supplementary steam pipeline. Compared with conventional high-pressure heaters, it does not need to re-drill holes on the cylinder, does not sacrifice the unit's economy, and reduces the unit's leakage points, thereby maximizing the unit's economy. In addition, it simplifies the pipeline design layout, saves construction period and subsequent inspection and maintenance costs.

Claims

1. A steam turbine supplementary steam reheating system, comprising a multi-stage high-pressure heater and a multi-stage low-pressure heater connected between a boiler and a steam turbine, a deaerator connected between the multi-stage high-pressure heater and the multi-stage low-pressure heater, the boiler and the high-pressure cylinder of the steam turbine are connected through a main steam pipeline, characterized in that: The multi-stage high-pressure heater includes a No. 0 high-pressure heater added between the No. 1 high-pressure heater and the boiler, the steam extraction port of the No. 0 high-pressure heater is arranged on the supplementary steam pipeline, the supplementary steam pipeline is connected between the main steam pipeline and the high-pressure cylinder, a supplementary air valve is installed on the supplementary steam pipeline, and the steam extraction port of the No. 0 high-pressure heater is located between the supplementary air valve and the high-pressure cylinder.

2. The steam turbine supplementary steam reheat system according to claim 1, characterized in that: A condenser, a condensate pump and a shaft seal heater are connected in sequence between the exhaust port of the low-pressure cylinder of the steam turbine and the multi-stage low-pressure heater. The shaft seal heater is connected to the condenser through a return pipe, and the air leakage of the self-sealing system is respectively connected to the last-stage low-pressure heater of the multi-stage low-pressure heater, the shaft seal heater and the hot well of the condenser.

3. The steam turbine supplementary steam reheat system according to claim 2, characterized in that: The multi-stage high-pressure heater also includes a high-pressure heater No. 2 and a high-pressure heater No.

3. The drain outlets of the high-pressure heater No. 0 and the high-pressure heater No. 1 are connected in parallel and then connected to the drain inlet of the high-pressure heater No.

2. The drain outlet of the high-pressure heater No. 2 is connected to the drain inlet of the high-pressure heater No. 3, and the drain outlet of the high-pressure heater No. 3 is connected to the deaerator.

4. The steam turbine supplementary steam reheat system according to claim 3, characterized in that: The multi-stage low-pressure heater comprises a No. 5 low-pressure heater, a No. 6 low-pressure heater, a No. 7 low-pressure heater and a No. 8 low-pressure heater which are connected in series in sequence, and the drain of the multi-stage low-pressure heater is connected by gravity step by step.

5. The steam turbine supplementary steam reheat system according to any one of claims 1 to 4, characterized in that: A regulating valve and a check valve are installed on the No. 0 high-pressure heater steam extraction pipeline.

6. The steam turbine supplementary steam reheat system according to claim 5, characterized in that: The intermediate pressure cylinder of the steam turbine is a double-flow intermediate pressure cylinder, and the low pressure cylinder of the steam turbine is a double-flow low pressure cylinder.

Images