Heat regeneration system of common heater of 1000MW ultra-supercritical primary reheat steam turbine

Abstract

The utility model discloses a regenerative system of a common heater of a 1000MW ultra-supercritical primary reheat steam turbine, and relates to a device for heating water by using steam. The regenerative system aims at solving the problems that the operation efficiency of an existing regenerative system of the 1000MW ultra-supercritical primary reheating steam turbine is reduced and the coal consumption is increased under the working condition of being lower than the design load. The regenerative system comprises a high-pressure cylinder, a first check valve, a second check valve and a first high-pressure heater. An air inlet of the high-pressure cylinder is communicated with a main steam outlet of the boiler, and an exhaust port of the high-pressure cylinder is communicated with a reheat steam inlet of the boiler; a first high-pressure extraction opening and a second high-pressure extraction opening of the high-pressure cylinder communicate with a steam inlet of the first high-pressure heater through a first check valve and a second check valve correspondingly.

Description

Technical Field

[0001] The utility model relates to a device for heating water using steam. Background Art

[0002] At present, most of the 1000MW ultra-supercritical units put into operation in my country are single-reheat units. Their existing heat recovery system is usually an eight-stage heat recovery system consisting of a three-stage high-pressure heater, a first-stage deaerator and a four-stage low-pressure heater, and an external steam cooler is added. Although this heat recovery system can ensure that the heat recovery extraction steam heats the feed water to a higher temperature and maintains a high operating efficiency of the unit when operating at the design load and above. However, in recent years, with the large-scale grid connection of new energy sources, the regulating role of traditional thermal power units has become increasingly important. A large number of units have deep peak regulation requirements, which can be as low as 20% of the design load. Under low-load conditions, the existing heat recovery system extraction pressure drops significantly, and its ability to increase the feed water temperature is significantly reduced, resulting in a decrease in the overall operating efficiency of the turbine and an increase in coal consumption. Utility Model Content

[0003] The purpose of the utility model is to overcome the problem that the heat recovery system of the existing 1000MW ultra-supercritical single-reheat steam turbine has reduced operating efficiency and increased coal consumption under conditions lower than the design load, and to provide a heat recovery system for a 1000MW ultra-supercritical single-reheat steam turbine.

[0004] The utility model discloses a heat recovery system for a 1000MW ultra-supercritical single-reheat steam turbine, comprising a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a first check valve, a second check valve, a first high-pressure heater, a second high-pressure heater, a third high-pressure heater, a deaerator, a condenser and a low-pressure heater group;

[0005] The air inlet of the high-pressure cylinder is connected to the main steam outlet of the boiler, and the exhaust port of the high-pressure cylinder is connected to the reheat steam inlet of the boiler;

[0006] The first high-pressure air extraction port and the second high-pressure air extraction port of the high-pressure cylinder are connected to the steam inlet of the first high-pressure heater through the first check valve and the second check valve respectively; the third high-pressure air extraction port of the high-pressure cylinder is connected to the steam inlet of the second high-pressure heater;

[0007] The feed water outlet of the second high pressure heater is communicated with the feed water inlet of the first high pressure heater; the feed water outlet of the first high pressure heater is communicated with the feed water inlet of the boiler; the drain outlet of the first high pressure heater is communicated with the drain inlet of the second high pressure heater;

[0008] The inlet of the intermediate pressure cylinder is connected to the reheat steam outlet of the boiler, and the outlet of the intermediate pressure cylinder is connected to the inlet of the low pressure cylinder;

[0009] The first intermediate-pressure air extraction port of the intermediate-pressure cylinder is connected to the steam inlet of the third high-pressure heater, and the second intermediate-pressure air extraction port of the intermediate-pressure cylinder is connected to the steam inlet of the deaerator; the hot water outlet of the deaerator is connected to the water supply inlet of the water supply outlet of the third high-pressure heater;

[0010] The feed water outlet of the third high-pressure heater is connected to the feed water inlet of the second high-pressure heater, the drain outlet of the second high-pressure heater is connected to the drain inlet of the third high-pressure heater, and the drain outlet of the third high-pressure heater is connected to the drain inlet of the deaerator;

[0011] The outlet of the low-pressure cylinder is connected to the inlet of the condenser, and the condensate outlet of the condenser is connected to the condensate inlet of the low-pressure heater;

[0012] The low-pressure exhaust port of the low-pressure cylinder is connected to the steam inlet of the low-pressure heater group, the cold water outlet of the low-pressure heater group is connected to the cold water inlet of the deaerator, and the drain outlet of the low-pressure heater group is connected to the drain inlet of the condenser.

[0013] The beneficial effects of the utility model are:

[0014] By adopting the method of using two-stage heat recovery extraction steam to share one heater, the two-stage heat recovery is not put into use at the same time under different loads. Therefore, the shared heater can increase the utilization rate of the heater, reduce costs and transformation cycles, and at the same time, ensure that the unit feed water temperature remains at a high level under full load conditions, thereby improving the overall operating efficiency of the turbine and achieving the goal of energy saving and carbon reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the heat recovery system of the 1000MW ultra-supercritical single-reheat steam turbine of the utility model. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0018] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention. Specific implementation method 1

[0020] The heat recovery system of the 1000MW ultra-supercritical single-reheat steam turbine of this embodiment includes a high-pressure cylinder 1, an intermediate-pressure cylinder 2, a low-pressure cylinder 3, a first check valve 5, a second check valve 6, a first high-pressure heater 7, a second high-pressure heater 8, a third high-pressure heater 9, a deaerator 10, a condenser 11 and a low-pressure heater group;

[0021] The air inlet of the high-pressure cylinder 1 is connected to the main steam outlet of the boiler 4, and the exhaust port of the high-pressure cylinder 1 is connected to the reheat steam inlet of the boiler 4;

[0022] The first high-pressure air extraction port and the second high-pressure air extraction port of the high-pressure cylinder 1 are connected to the steam inlet of the first high-pressure heater 7 through the first check valve 5 and the second check valve 6 respectively; the third high-pressure air extraction port of the high-pressure cylinder 1 is connected to the steam inlet of the second high-pressure heater 8;

[0023] The feed water outlet of the second high pressure heater 8 is communicated with the feed water inlet of the first high pressure heater 7; the feed water outlet of the first high pressure heater 7 is communicated with the feed water inlet of the boiler 4; the drain outlet of the first high pressure heater 7 is communicated with the drain inlet of the second high pressure heater 8;

[0024] The inlet of the intermediate pressure cylinder 2 is connected to the reheat steam outlet of the boiler 4, and the outlet of the intermediate pressure cylinder 2 is connected to the inlet of the low pressure cylinder 3;

[0025] The first intermediate pressure air extraction port of the intermediate pressure cylinder 2 is connected to the steam inlet of the third high pressure heater 9, and the second intermediate pressure air extraction port of the intermediate pressure cylinder 2 is connected to the steam inlet of the deaerator 10; the hot water outlet of the deaerator 10 is connected to the water supply inlet of the water supply outlet of the third high pressure heater 9;

[0026] The water supply outlet of the third high-pressure heater 9 is connected to the water supply inlet of the second high-pressure heater 8, the drain outlet of the second high-pressure heater 8 is connected to the drain inlet of the third high-pressure heater 9, and the drain outlet of the third high-pressure heater 9 is connected to the drain inlet of the deaerator 10;

[0027] The outlet of the low-pressure cylinder 3 is connected to the inlet of the condenser 11, and the condensate outlet of the condenser 11 is connected to the condensate inlet of the low-pressure heater;

[0028] The low-pressure exhaust port of the low-pressure cylinder 3 is connected to the steam inlet of the low-pressure heater group, the cold water outlet of the low-pressure heater group is connected to the cold water inlet of the deaerator 10, and the drain outlet of the low-pressure heater group is connected to the drain inlet of the condenser 11.

[0029] Specifically, the heat recovery system of the 1000MW ultra-supercritical once-reheat steam turbine of this embodiment is mainly applied to the 1000MW ultra-supercritical once-reheat steam turbine. The specific working process is as follows:

[0030] Under high load, the first check valve 5 is closed, the second check valve 6 is opened, the condensed water heated by the low-pressure heater group is heat exchanged with the steam of the second medium-pressure steam extraction port in the deaerator 10, and then the heated water is heat exchanged with the steam of the first medium-pressure steam extraction port in the third high-pressure heater 9, and then the heated water is heat exchanged with the steam of the third high-pressure steam extraction port in the second high-pressure heater 8, and then the heated water is heat exchanged with the steam of the second high-pressure steam extraction port in the shared first high-pressure heater 7 to form high-pressure feed water, and the high-pressure feed water enters the boiler 4. Under high load, the steam temperature of the second high-pressure steam extraction port can maintain a high heat recovery efficiency, so the first high-pressure steam extraction port is closed, and the feed water is heated by the above-mentioned heat recovery system.

[0031] Under low load, the first check valve 5 is opened, the second check valve 6 is closed, the condensed water heated by the low-pressure heater group is heat exchanged with the steam of the second medium-pressure extraction port in the deaerator 10, and then the heated water is heat exchanged with the steam of the first medium-pressure extraction port in the third high-pressure heater 9, and then the heated water is heat exchanged with the steam of the third high-pressure extraction port in the second high-pressure heater 8, and then the heated water is heat exchanged with the steam of the first high-pressure extraction port in the shared first high-pressure heater 7 to form high-pressure feed water, and the high-pressure feed water enters the boiler 4. Under low load, the steam temperature of the second high-pressure extraction port is insufficient, so the second high-pressure extraction port is closed, and the feed water is heated by the above-mentioned heat recovery system.

[0032] The above technical solution adopts the method of using two-stage heat recovery extraction steam in the high-pressure cylinder 1 to share a heater (the first high-pressure heater 7). Under different loads, the two-stage heat recovery is not used at the same time. Therefore, the shared heater can improve the heater utilization rate, reduce costs and transformation cycles, and at the same time, it can ensure that the unit feed water temperature remains at a high level under full load conditions, improve the system thermal efficiency, and achieve the purpose of energy saving and carbon reduction. The specific effect comparison is as follows:

[0033]

[0034] Compared with the existing heat recovery system, the heat rate is reduced by 12.6 kJ / kW.h at 75% load, 11.5 kJ / kW.h at 50% load, and 11.2 kJ / kW.h at 30% load. The feed water temperature is increased by 11.5°C at 75% load, 10.6°C at 50% load, and 9.7°C at 30% load. The system thermal efficiency is increased by 0.08% at 75% load, 0.07% at 50% load, and 0.06% at 30% load. Specific implementation method 2

[0036] This embodiment is a further description of the first embodiment. In this embodiment, a feedwater heater 12 is also included;

[0037] The feed water outlet of the first high pressure heater 7 is also communicated with the feed water inlet of the feed water heater 12 , and the feed water outlet of the feed water heater 12 is communicated with the feed water inlet of the boiler 4 .

[0038] The other technical features of this embodiment are exactly the same as those of the first embodiment.

[0039] Specifically, the high-pressure feed water in the first high-pressure heater 7 can be heated by an external feed water heater 12 and then fed into the feed water inlet of the boiler 4 .

[0040] Under high load, the first high-pressure heater 7 exchanges heat with the feed water from the second high-pressure heater 8 and the steam from the second high-pressure steam extraction port to form high-pressure feed water, and the high-pressure feed water can be heated by the external feed water heater 12 and then enter the boiler 4.

[0041] Under low load, the first high-pressure heater 7 exchanges heat between the feed water from the second high-pressure heater 8 and the steam from the first high-pressure steam extraction port to form high-pressure feed water, and the high-pressure feed water can be heated by the external feed water heater 12 and then enter the boiler 4. Specific implementation method three

[0043] This embodiment is a further description of the first or second embodiment. In this embodiment, a water supply pump 13 is also included;

[0044] The hot water outlet of the deaerator 10 is connected to the feed water inlet of the third high-pressure heater 9 through the feed water pump 13 .

[0045] The other technical features of this embodiment are exactly the same as those of embodiment one or two.

[0046] Specifically, the water feed pump 13 is used to increase the pressure of the water in the deaerator 10 and then feed it to the subsequent process.

[0047] The deaerator 10 exchanges heat between the condensed water heated by the low-pressure heater group and the steam from the second medium-pressure steam extraction port, and then the condensed water is pumped to the water inlet of the third high-pressure heater 9 after being pressurized by the water pump 13. Specific implementation method four

[0049] This embodiment is a further description of the third embodiment. In this embodiment, the low-pressure heater group includes a first low-pressure heater 14, a second low-pressure heater 15, a third low-pressure heater 16 and a fourth low-pressure heater 17;

[0050] The low-pressure air suction port of the low-pressure cylinder 3 includes a first low-pressure air suction port, a second low-pressure air suction port, a third low-pressure air suction port and a fourth low-pressure air suction port;

[0051] The first low-pressure air extraction port, the second low-pressure air extraction port, the third low-pressure air extraction port and the fourth low-pressure air extraction port are respectively connected to the steam inlets of the first low-pressure heater 14, the second low-pressure heater 15, the third low-pressure heater 16 and the fourth low-pressure heater 17;

[0052] The cold water outlet of the first low-pressure heater 14 serves as the cold water outlet of the low-pressure heater, and the condensed water inlet of the fourth low-pressure heater 17 serves as the condensed water inlet of the low-pressure heater;

[0053] The condensate inlet and drain outlet of the first low-pressure heater 14 are respectively connected to the condensate outlet and drain inlet of the second low-pressure heater 15;

[0054] The condensate inlet and drain outlet of the second low-pressure heater 15 are respectively connected to the condensate outlet and drain inlet of the third low-pressure heater 16;

[0055] The condensate inlet and drain outlet of the third low-pressure heater 16 are communicated with the condensate outlet and drain inlet of the fourth low-pressure heater 17 , respectively.

[0056] The other technical features of this embodiment are exactly the same as those of the third embodiment.

[0057] Specifically, the low-pressure heater group is divided into a plurality of groups, which are used to perform multi-stage heat exchange with the air suction port of the low-pressure cylinder 3 on a one-to-one basis to perform multi-stage heating on the condensate.

[0058] The condensed water from the condenser 11 is heat exchanged with the steam from the low-pressure extraction port No. 4 in the fourth low-pressure heater 17, and then the heated water is heat exchanged with the steam from the low-pressure extraction port No. 3 in the third low-pressure heater 16, and then the heated water is heat exchanged with the steam from the low-pressure extraction port No. 2 in the second low-pressure heater 15, and then the heated water is heat exchanged with the steam from the low-pressure extraction port No. 1 in the first low-pressure heater 14. Specific implementation method five

[0060] This embodiment is a further description of the fourth embodiment. In this embodiment, a shaft seal heater 18 is further included;

[0061] The condensate outlet of the condenser 11 is communicated with the condensate inlet of the shaft seal heater 18, and the condensate outlet of the shaft seal heater 18 is communicated with the condensate inlet of the fourth low-pressure heater 17;

[0062] The drain outlet of the shaft seal heater 18 is communicated with the drain inlet of the condenser 11 .

[0063] The other technical features of this embodiment are exactly the same as those of embodiment 4.

[0064] Specifically, the condensate from the condenser 11 may also be heated by the shaft seal heater 18 before being sent to the low-pressure heater group.

[0065] The shaft seal heater 18 can recover the gas leakage from each stage of the steam seal and use the heat to heat the condensed water, thereby further recovering the steam. Specific implementation method 6

[0067] This embodiment is a further description of the fifth embodiment. In this embodiment, a condensate pump 19 is also included;

[0068] The condensate outlet of the condenser 11 is communicated with the condensate inlet of the shaft seal heater 18 via a condensate pump 19 .

[0069] The other technical features of this embodiment are exactly the same as those of embodiment five.

[0070] Specifically, the condensate pump 19 is used to boost the condensate of the condenser 11 and pump it to the subsequent process.

[0071] The condensate pump 19 pumps the condensate from the condenser 11 to the shaft seal heater 18 for heating. Specific implementation method seven

[0073] This embodiment is a further description of the first, second, fourth, fifth or sixth embodiment. In this embodiment, a controller and a load sensor are also included.

[0074] The load sensor can detect the real-time load of the primary reheat steam turbine and send it to the controller;

[0075] The controller can compare the real-time load with the pre-stored load threshold, and control the first check valve 5 to close and the second check valve 6 to open when the real-time load is greater than or equal to the load threshold; and control the first check valve 5 to open and the second check valve 6 to close when the real-time load is less than the load threshold.

[0076] The other technical solutions of this embodiment are exactly the same as those of embodiments one, two, four, five or six.

[0077] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the features of the various dependent claims and herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with the individual embodiments may be used in other embodiments.

Claims

1. A heat recovery system for a 1000MW ultra-supercritical primary reheat steam turbine common heater, characterized in that: It comprises a high-pressure cylinder (1), a medium-pressure cylinder (2), a low-pressure cylinder (3), a first check valve (5), a second check valve (6), a first high-pressure heater (7), a second high-pressure heater (8), a third high-pressure heater (9), a deaerator (10), a condenser (11) and a low-pressure heater group; The air inlet of the high-pressure cylinder (1) is connected to the main steam outlet of the boiler (4), and the exhaust port of the high-pressure cylinder (1) is connected to the reheat steam inlet of the boiler (4); The first high-pressure air extraction port and the second high-pressure air extraction port of the high-pressure cylinder (1) are respectively connected to the steam inlet of the first high-pressure heater (7) through the first check valve (5) and the second check valve (6); the third high-pressure air extraction port of the high-pressure cylinder (1) is connected to the steam inlet of the second high-pressure heater (8); The feed water outlet of the second high-pressure heater (8) is communicated with the feed water inlet of the first high-pressure heater (7); the feed water outlet of the first high-pressure heater (7) is communicated with the feed water inlet of the boiler (4); the drain outlet of the first high-pressure heater (7) is communicated with the drain inlet of the second high-pressure heater (8); The inlet of the intermediate pressure cylinder (2) is connected to the reheat steam outlet of the boiler (4), and the outlet of the intermediate pressure cylinder (2) is connected to the inlet of the low pressure cylinder (3); The first medium-pressure air extraction port of the medium-pressure cylinder (2) is in communication with the steam inlet of the third high-pressure heater (9), and the second medium-pressure air extraction port of the medium-pressure cylinder (2) is in communication with the steam inlet of the deaerator (10); the hot water outlet of the deaerator (10) is in communication with the water supply inlet of the water supply outlet of the third high-pressure heater (9); The water supply outlet of the third high-pressure heater (9) is connected to the water supply inlet of the second high-pressure heater (8), the drain outlet of the second high-pressure heater (8) is connected to the drain inlet of the third high-pressure heater (9), and the drain outlet of the third high-pressure heater (9) is connected to the drain inlet of the deaerator (10); The outlet of the low-pressure cylinder (3) is connected to the inlet of the condenser (11), and the condensate outlet of the condenser (11) is connected to the condensate inlet of the low-pressure heater; The low-pressure exhaust port of the low-pressure cylinder (3) is connected to the steam inlet of the low-pressure heater group, the cold water outlet of the low-pressure heater group is connected to the cold water inlet of the deaerator (10), and the drain outlet of the low-pressure heater group is connected to the drain inlet of the condenser (11).

2. The heat recovery system of a 1000MW ultra-supercritical primary reheat steam turbine common heater according to claim 1, characterized in that: Also includes a feedwater heater (12); The feed water outlet of the first high-pressure heater (7) is also connected to the feed water inlet of the feed water heater (12), and the feed water outlet of the feed water heater (12) is connected to the feed water inlet of the boiler (4).

3. A heat recovery system for a 1000MW ultra-supercritical primary reheat steam turbine common heater according to claim 1 or 2, characterized in that: Also includes a water supply pump (13); The hot water outlet of the deaerator (10) is connected to the water supply inlet of the third high-pressure heater (9) through the water supply pump (13).

4. The heat recovery system of a 1000MW ultra-supercritical primary reheat steam turbine common heater according to claim 3, characterized in that: The low-pressure heater group includes a first low-pressure heater (14), a second low-pressure heater (15), a third low-pressure heater (16) and a fourth low-pressure heater (17); The low-pressure air suction port of the low-pressure cylinder (3) comprises a first low-pressure air suction port, a second low-pressure air suction port, a third low-pressure air suction port and a fourth low-pressure air suction port; The first low-pressure air extraction port, the second low-pressure air extraction port, the third low-pressure air extraction port and the fourth low-pressure air extraction port are respectively connected to the steam inlets of the first low-pressure heater (14), the second low-pressure heater (15), the third low-pressure heater (16) and the fourth low-pressure heater (17); The cold water outlet of the first low-pressure heater (14) serves as the cold water outlet of the low-pressure heater, and the condensed water inlet of the fourth low-pressure heater (17) serves as the condensed water inlet of the low-pressure heater; The condensate inlet and drain outlet of the first low-pressure heater (14) are respectively connected to the condensate outlet and drain inlet of the second low-pressure heater (15); The condensate inlet and drain outlet of the second low-pressure heater (15) are respectively connected to the condensate outlet and drain inlet of the third low-pressure heater (16); The condensate inlet and drain outlet of the third low-pressure heater (16) are respectively connected to the condensate outlet and drain inlet of the fourth low-pressure heater (17).

5. The heat recovery system of a 1000MW ultra-supercritical primary reheat steam turbine common heater according to claim 4, characterized in that: Also includes a shaft seal heater (18); The condensate outlet of the condenser (11) is communicated with the condensate inlet of the shaft seal heater (18), and the condensate outlet of the shaft seal heater (18) is communicated with the condensate inlet of the fourth low-pressure heater (17); The drain outlet of the shaft seal heater (18) is communicated with the drain inlet of the condenser (11).

6. The heat recovery system of a 1000MW ultra-supercritical primary reheat steam turbine common heater according to claim 5, characterized in that: Also includes a condensate pump (19); The condensate outlet of the condenser (11) is connected to the condensate inlet of the shaft seal heater (18) through a condensate pump (19).

7. A heat recovery system for a 1000MW ultra-supercritical primary reheat steam turbine common heater according to claim 1, 2, 4, 5 or 6, characterized in that: Also includes a controller and a load sensor; The load sensor can detect the real-time load of the primary reheat steam turbine and send it to the controller; The controller can compare the real-time load with a pre-stored load threshold, and when the real-time load is greater than or equal to the load threshold, control the first check valve (5) to close and the second check valve (6) to open; when the real-time load is less than the load threshold, control the first check valve (5) to open and the second check valve (6) to close.

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