Rapid Enhancement of Working Medium Side Energy Supply System for Subcritical Boilers

Abstract

The present invention discloses a subcritical boiler rapid enhanced working medium side energy supply system, including: a water supply pipeline connected to the drum, on which a water supply pump and an economizer are arranged in sequence; a circulating water loop connected to the drum; a high-temperature boiler water energy storage device; a connecting pipe connected to the drum and leading the high-temperature and high-pressure saturated water in the drum to the high-temperature boiler water energy storage device when the valve is opened; a water supply branch provided with an opening and closing valve, the water supply branch connecting the water supply pipeline and the circulating water loop; a boiler water mixing header provided in the water supply branch; an energy release pipeline provided with a valve three, when the valve is opened, the energy release side of the high-temperature boiler water energy storage device is connected to the boiler water mixing header through the energy release pipeline. By adopting this scheme, the rapid increase of the boiler evaporation rate is achieved, and the rapid and flexible peak-shaving capability of the unit is improved; due to the presence of the high-temperature boiler water energy storage device, the start-up time of the boiler in cold start or warm start can also be greatly shortened, further improving the rapid and flexible peak-shaving capability of the unit boiler.

Description

Technical Field

[0001] The invention relates to a boiler energy supply system for a thermal power generating unit, and in particular to a new system suitable for fast and flexible peak load regulation of a boiler in a subcritical unit. Background Art

[0002] Under the "dual carbon" goal, the power supply structure and power consumption structure of the power system will undergo significant changes. The introduction of large proportions of intermittent power sources such as wind and light will put forward higher requirements on the peak-shaving performance and rapid response capabilities of existing thermal power generating units.

[0003] The load change rate of existing traditional thermal power generating units is generally 1.0% to 1.5% of rated load / minute, and the maximum load change rate can reach 2.0% of rated load / minute. In the future, the new power system with renewable energy as the main body will put forward higher requirements for the peak load rate of thermal power generating units (5.0% to 8.0% of rated load / minute), but the current traditional thermal power generating units still cannot meet the above requirements in terms of load change rate. The key to solving this problem is to achieve rapid energy supply of thermal power generating unit boilers. Therefore, how to achieve the rapid load change capability and response rate of thermal power generating unit boilers and realize rapid and flexible peak load regulation of thermal power generating unit boilers is a problem that needs to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to provide a new energy supply system which can enhance the rapid peak regulation and load variation capabilities of a subcritical boiler from the working medium side.

[0005] The object of the present invention is achieved as follows: a subcritical boiler rapid strengthening working medium side energy supply system, comprising:

[0006] A water supply pipeline connected to the drum, wherein a water supply pump and an economizer are arranged in sequence on the water supply pipeline;

[0007] A circulating water loop connected to the steam drum to circulate water;

[0008] It is a high-temperature boiler water energy storage device with a high-temperature resistant and pressure-bearing structure;

[0009] An energy storage pipeline having an opening and closing valve, connected to the steam drum and conveying the high-temperature saturated water in the steam drum to the high-temperature boiler water energy storage device when the valve is opened, wherein the energy storage pipeline connects the water cavity in the steam drum and the high-temperature boiler water energy storage device;

[0010] A water supply branch is provided with an opening and closing valve, and when the valve is opened, the water supply branch is connected to the water supply pipeline and the circulating water loop;

[0011] A boiler water mixing header installed in the water supply branch;

[0012] An energy release pipeline is provided with a second valve, and when the valve is opened, the energy release side of the high-temperature boiler water energy storage device is connected to the boiler water mixing header through the energy release pipeline;

[0013] The exhaust steam pipeline is connected to the steam chamber in the steam drum and the steam chamber of the high-temperature boiler water energy storage device.

[0014] Furthermore, the exhaust steam pipeline is provided with an exhaust valve, and the energy storage pipeline is provided with a valve 1.

[0015] Furthermore, in the energy storage stage, the valve 1 and the drain valve are both in an open state.

[0016] Furthermore, the height position of the high-temperature boiler water energy storage device is lower than the height position of the steam drum.

[0017] Furthermore, the boiler water mixing header is located below the high-temperature boiler water energy storage device.

[0018] Furthermore, a boiler water pump is provided on the water supply branch line, and a suction end of the boiler water pump is connected to the water outlet side of the boiler water mixing header.

[0019] Furthermore, the water supply branch is provided with a valve four, which is located downstream of the output end of the boiler water pump. The valve four is in an open state when the unit needs to quickly increase the load and emergency cold or hot start.

[0020] Furthermore, a valve three is provided at a position close to the input point of the water supply branch, and the valve three is in an open state when the unit needs to quickly increase the load and emergency cold or hot start.

[0021] Furthermore, the drain valve is in an open state when the unit needs to quickly increase load and emergency cold or hot start.

[0022] The beneficial effects of the present invention are as follows: the system is suitable for the rapid load change conditions of the subcritical boiler of a thermal power generating unit and the cold / hot start conditions of the unit. When the unit is in the load increase condition, the high-temperature boiler water energy storage device can quickly provide high-quality hot water to the boiler to increase the thermal enthalpy of the working fluid entering the furnace. At the same time, with the rapid supply of fuel on the furnace side, the evaporation amount of the boiler is rapidly increased, thereby improving the rapid and flexible peak-shaving capability of the unit. In addition, due to the presence of the high-temperature boiler water energy storage device, the start-up time of the boiler during cold start or warm start can be greatly shortened, further improving the rapid and flexible peak-shaving capability of the unit boiler. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a system layout diagram of the present invention. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0025] like Figure 1 As shown, a subcritical boiler rapid enhanced working fluid side energy supply system is proposed, including:

[0026] The water supply pipeline 3 of the steam drum 4 is connected, and the water supply pipeline 3 is provided with a water supply pump 1 and an economizer 2 in sequence;

[0027] A circulating water loop 5 connected to the steam drum 4 to circulate water;

[0028] Superheater 7, hot steam output from the steam chamber of drum 4 passes through superheater 7;

[0029] A high-temperature boiler water energy storage device 12 is provided with a high-temperature resistant and pressure-bearing structure;

[0030] An energy storage pipeline 11 is provided with an opening and closing valve, connected to the drum 4 and passing the high-temperature saturated water in the drum 4 to the high-temperature boiler water energy storage device 12 when the valve is opened, and the energy storage pipeline 11 connects the water cavity in the drum 4 and the high-temperature boiler water energy storage device 12;

[0031] A water supply branch 16 with an opening and closing valve is provided, and when the valve is opened, the water supply branch 16 connects the water supply pipeline 3 and the circulating water loop 5;

[0032] A boiler water mixing header 17 provided in the water supply branch 16;

[0033] An energy release pipe 13 with a valve 2 14 is provided. When the valve is opened, the energy release side of the high-temperature boiler water energy storage device 12 is connected to the boiler water mixing header 17 through the energy release pipe 13 .

[0034] Among them, the system also includes an exhaust pipe 9, which connects the upper steam chamber in the drum 4 and the upper steam chamber of the high-temperature boiler water energy storage device 12. The exhaust pipe 9 is provided with a drain valve 8, which is in an open state when the unit needs to quickly increase the load and emergency cold or hot start. The energy storage pipe 11 connects the water chamber in the drum 4 and the high-temperature boiler water energy storage device 12. The energy storage pipe 11 is provided with a valve 10. In the energy storage stage, the valve 10 and the drain valve 8 are both in an open state. The high-temperature boiler water energy storage device 12 passes steam into the drum 4 through a pipeline to balance the pressure between the high-temperature boiler water energy storage device 12 and the drum 4 to maintain pressure balance; when no energy storage is required, the valve 10 and the drain valve 8 are closed, and the connection / isolation between the high-temperature boiler water energy storage device 12 and the drum 4 is achieved by opening / closing the valve 10 and the drain valve 8.

[0035] The height of the high-temperature boiler water energy storage device 12 is lower than the height of the steam drum 4 , and the boiler water mixing header 17 is located below the high-temperature boiler water energy storage device 12 .

[0036] A boiler water supplement pump 18 is provided on the water supply branch 16 , and a suction end of the boiler water supplement pump 18 is connected to the water outlet side of the boiler water mixing header 17 .

[0037] The water supply branch 16 is provided with a valve 4 19, which is located downstream of the output end of the boiler water pump 18. The valve 4 19 is in an open state when the unit needs to quickly increase the load and emergency cold or hot start.

[0038] A valve 3 15 is provided near the input point of the water supply branch 16. The valve 3 15 is in an open state when the unit needs to quickly increase the load and emergency cold or hot start.

[0039] By adjusting the opening of valve two 14 and valve three 15, the working medium temperature of the boiler water mixing tank 17 can be controlled and adjusted. The outlet of the boiler water mixing tank 17 is connected to the circulating water loop 5 of the boiler through a pipeline, a boiler water pump 18 and valve four 19. The energy storage device can release energy, quickly change load process, and isolate the new energy supply system from the original boiler circulating water system by opening / starting valve two 14, valve three 15, valve four 19 and starting the boiler water pump 18.

[0040] During normal load operation of the unit, valve one 10, valve two 14, valve three 15, valve four 19, drain valve 8 and boiler water pump 18 are closed. At this time, the working medium side energy storage-energy supply system is isolated from the original boiler working medium circulation system. The feed water is pumped in by the feed water pump 1, enters the steam drum 4 after being heated by the economizer 2, and the steam drum 4 receives the feed water and supplies water to the circulating water loop 5 through the downcomer. The heating and evaporation process of the working medium in the boiler furnace 6 is realized through the driving force of natural circulation or controlled circulation (with boiler water circulation pump).

[0041] During the period of high-load operation and energy storage of the unit or when rapid load reduction is required, in addition to the normal supply of high-quality steam to the outside by the boiler, energy is stored in the high-temperature boiler water energy storage device 12 by opening valve 10 and the drain valve 8 on the top of the boiler water heat storage device. At the same time, valves 2 14, 3 15, and 4 19 are in a closed state, and the boiler water pump 18 is in a standby state. In addition, the distribution ratio of saturated water in the steam drum 4 to the downcomer and the high-temperature boiler water energy storage device 12 can be adjusted by adjusting the opening of valve 10 to keep the pressure in the energy storage device and the pipeline below 17MPa and the working medium temperature below 400℃ to ensure safe and stable operation of the boiler. When the energy storage process is completed, valve 10 and the drain valve 8 are closed to achieve isolation between the high-temperature boiler water energy storage device 12 and the original boiler water circulation system.

[0042] During the period when the unit needs to quickly increase the load and peak, the energy storage-energy supply system on the working fluid side needs to release energy quickly. Open valve two 14, valve three 15, valve four 19 and drain valve 8, and start the boiler water pump 18. At the same time, valve one 10 is in a closed state. The high-temperature boiler water and the low-temperature feed water are fully mixed in the boiler water mixing tank 17 and then pumped into the circulating water loop 5 of the boiler furnace 6 through the boiler water pump 18 to quickly increase the thermal enthalpy of the working fluid entering the furnace, and by increasing the amount of fuel entering the furnace, the boiler evaporation capacity and the variable load response rate are quickly increased; in addition, in the high-temperature furnace During the energy release process of the water energy storage device 12, the opening of valve three 15 is automatically adjusted to keep the inlet water temperature of the boiler water pump 18 in a controllable state, and the inlet water temperature of the boiler water pump 18 is kept below 400°C to prevent the occurrence of local vaporization and ensure the safety of the water circulation system; after the energy release process of the high-temperature boiler water energy storage device 12 is completed, valve two 14, valve three 15, valve four 19 and boiler water pump 18 are closed to achieve isolation between the high-temperature boiler water energy storage system and the original boiler water circulation system, and the unit boiler is ready to carry out the next energy storage process under non-peak-shaving conditions.

[0043] Since the high-temperature boiler water energy storage device 12 stores high-quality hot water (high temperature and high pressure), the energy storage and release process of the high-temperature boiler water energy storage device 12 must be carried out regularly according to the load operation of the unit to ensure that the high-temperature boiler water energy storage device 12 is always in an available state and at a relatively high temperature level, so that the unit boiler can be equipped with the ability to respond to rapid load changes at any time.

[0044] Since this new energy supply system needs to adjust the hot water mixing temperature, pressure, flow rate and other parameters during load climbing in real time, it has high requirements for the adjustment response capability and response speed. Therefore, it is necessary to match the corresponding control system and control strategy to achieve real-time adjustment and control of the new energy supply system.

[0045] The above are preferred implementation cases of the present invention. Ordinary technicians in this field can also make various changes or improvements on this basis. Without departing from the overall concept of the present invention, these changes or improvements should fall within the scope of protection required by the present invention.

Claims

1. Rapid strengthening of the working fluid side energy supply system of subcritical boilers, include: A water supply pipeline (3) connected to the steam drum (4), wherein a water supply pump (1) and a coal economizer (2) are sequentially arranged on the water supply pipeline (3); A circulating water circuit (5) connected to the steam drum (4) to circulate water; It is characterized by further comprising: A high-temperature boiler water energy storage device (12) is provided with a certain high-temperature resistance and pressure-bearing structure; An energy storage pipeline (11) is provided with an opening and closing valve, is connected to the steam drum (4), and when the valve is opened, the high-temperature saturated water in the steam drum (4) is passed to the high-temperature boiler water energy storage device (12), wherein the energy storage pipeline (11) connects the water cavity in the steam drum (4) and the high-temperature boiler water energy storage device (12); A water supply branch (16) is provided with an opening and closing valve, and when the valve is opened, the water supply branch (16) is connected to the water supply pipeline (3) and the circulating water loop (5); A boiler water mixing header (17) disposed in the water supply branch (16); An energy release pipe (13) having a second valve (14) is provided, and when the valve is opened, the energy release side of the high-temperature boiler water energy storage device (12) is connected to the boiler water mixing header (17) through the energy release pipe (13); An exhaust steam pipeline (9), wherein the exhaust steam pipeline (9) is connected to the steam chamber in the steam drum (4) and the steam chamber of the high-temperature boiler water energy storage device (12); Wherein, a boiler water pump (18) is provided on the water supply branch (16), and the suction end of the boiler water pump (18) is connected to the water outlet side of the boiler water mixing header (17).

2. The subcritical boiler rapid enhanced working medium side energy supply system according to claim 1, Features: The exhaust steam pipeline (9) is provided with an exhaust valve (8), and the energy storage pipeline (11) is provided with a valve 1 (10).

3. The subcritical boiler rapid enhanced working medium side energy supply system according to claim 2, Features: During the energy storage stage, the valve 1 (10) and the drain valve (8) are both in an open state.

4. The subcritical boiler rapid enhanced working medium side energy supply system according to claim 2, Features: The height of the high-temperature boiler water energy storage device (12) is lower than the height of the steam drum (4).

5. The subcritical boiler rapid enhanced working medium side energy supply system according to claim 1, Features: The boiler water mixing header (17) is located below the high-temperature boiler water energy storage device (12).

6. The subcritical boiler rapid enhanced working medium side energy supply system according to claim 1, Features: The water supply branch (16) is provided with a valve four (19), and the valve four (19) is located downstream of the output end of the boiler water pump (18). The valve four (19) is in an open state when the unit needs to quickly increase the load and emergency cold or hot start.

7. The subcritical boiler rapid enhanced working medium side energy supply system according to claim 6, Features: A valve three (15) is provided at a position close to the input point of the water supply branch (16), and the valve three (15) is in an open state when the unit needs to quickly increase load and emergency cold or hot start.

8. The subcritical boiler rapid enhanced working medium side energy supply system according to claim 2, Features: The drain valve (8) is in an open state when the unit needs to quickly increase load or is urgently started in a cold or hot state.

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