A system for wet-state water atomization recovery of a supercritical unit in a thermal power plant
By designing a wet water atomization recovery system, wet water is converted into overheated or saturated steam for heating for users, the problem of wet water waste during low-load operation of supercritical units is solved, and efficient recycling and economic improvement is achieved.
Patent Information
- Application Number
- CN202010463005.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2020-05-27
- Publication Date
- 2025-08-05
- Estimated Expiration
- 2040-05-27
AI Technical Summary
In the prior art, wet water cannot be efficiently recycled and utilized during low load operation of supercritical units, resulting in direct waste of high-grade water, increasing the unit's heat consumption rate and working fluid waste, and recycling is more difficult.
A wet water atomization recovery system is designed, including a wet water conversion device, auxiliary steam pipeline, boiler start separator water storage tank and related valves and instruments. The wet water is converted into overheated or saturated steam for heating by auxiliary steam heating atomization nozzle.
It realizes efficient recycling and utilization of wet water, reduces the unit's heat consumption rate and power generation coal consumption rate, improves the unit's economy, and has a simple structure and convenient operation.
Smart Images
Figure CN111503607B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of steam turbine operation and relates to a system for wet state water atomization recovery of a supercritical unit in a thermal power plant. Background Art
[0002] China has implemented the flexibility transformation of 220 million kilowatts of coal-fired units, enabling the units to have the ability of deep peak shaving. The peak shaving capacity of condensing units is increased by 15 - 20% of the rated capacity, and the minimum technical output reaches 30 - 35% of the rated capacity. In some provinces and regions, a greater depth of peak shaving is required for thermal power units, and a relatively high on-grid electricity price subsidy is provided for the deep peak shaving units. Therefore, some thermal power units need to operate at a deep peak shaving level below 20% of the rated load.
[0003] However, for supercritical units, when the unit load is reduced below 25% of the rated load, the boiler switches from the dry state to the wet state operation, and a large amount of saturated water will be generated in the steam-water separator. For boilers without a furnace circulating pump, the continuously accumulating water in the steam-water separator will be directly discharged into the drain expansion vessel or the condenser through the water level overflow regulating valve (abbreviated as the "361 valve"), resulting in a direct waste of high-quality water. When the unit operates at a low load in this way, the unit has a high heat consumption rate and causes waste of working medium. Due to economic operation considerations, power plants urgently need to recycle and utilize this part of the discharged high-energy water. However, so far, there are relatively few systems for wet state water recovery. In addition, although the quality of this wet state water is relatively high, it is in a high-pressure saturated state, making it difficult to recycle and utilize. Summary of the Invention
[0004] The purpose of the invention is to overcome the above-mentioned disadvantages of the prior art and provide a system for wet state water atomization recovery of a supercritical unit in a thermal power plant, which can achieve the full recycling and utilization of high-energy wet state water.
[0005] To achieve the above purpose, the system for wet state water atomization recovery of a supercritical unit in a thermal power plant described in the invention includes a wet state water conversion device, an auxiliary steam pipeline, a boiler start-up separator water storage tank, a shut-off valve, a flow control valve and a manual valve;
[0006] The wet state water conversion device includes an auxiliary steam pipeline, a housing, and an auxiliary steam heating device and an atomizing nozzle arranged in the housing. Among them, the auxiliary steam pipeline is connected to the inlet of the auxiliary steam heating device. The auxiliary steam heating device is installed on the front side of the atomizing nozzle, and the air flow direction output by the auxiliary steam heating device points to the nozzle of the atomizing nozzle. The outlet of the boiler start-up separator water storage tank is connected to the inlet of the atomizing nozzle through a shut-off valve, a flow control valve and a manual valve, and the outlet of the housing is connected to a heat user.
[0007] On the pipeline between the outlet of the water storage tank of the boiler start-up separator and the shut-off valve, a wet state water measuring instrument, a wet state water temperature measuring instrument and a flow measuring instrument are provided.
[0008] On the pipeline between the shell and the heat user, a converted steam temperature measuring instrument and a converted steam pressure measuring instrument are provided.
[0009] It also includes a host computer. Among them, the host computer is connected to the wet state water measuring instrument, the wet state water temperature measuring instrument, the flow measuring instrument, the converted steam temperature measuring instrument, the converted steam pressure measuring instrument, the shut-off valve and the flow control valve.
[0010] On the pipeline between the shell and the heat user, a safety valve is provided.
[0011] The form, quantity and layout mode of the atomizing nozzles are selected according to the flow rate and atomizing requirements of the wet state water.
[0012] Each nozzle on the atomizing nozzle is evenly arranged in a matrix or evenly arranged circumferentially.
[0013] The auxiliary steam introduced into the auxiliary steam pipeline is wet steam or superheated steam.
[0014] During operation, after the boiler switches to wet state operation, wet state water is generated in the start-up separator of the boiler. When the amount of wet state water reaches the preset amount, the wet state water in the water storage tank of the boiler start-up separator is detected for water pressure by the wet state water measuring instrument, the water temperature is detected by the wet state water temperature measuring instrument, and the flow rate is detected by the flow measuring instrument. Then, it enters the wet state water conversion device through the shut-off valve, the flow control valve and the manual valve. Among them, in the wet state water conversion device, the wet state water is sprayed out in the form of atomized water droplets by the atomizing nozzle, and then heated by the auxiliary steam to become superheated steam or saturated steam. Finally, the pressure is measured by the converted steam pressure measuring instrument and the temperature is measured by the converted steam temperature measuring instrument, and then it is sent to the heat user.
[0015] When the heat user needs superheated steam, the flow rate of the auxiliary steam is increased to ensure that the steam on the user side is superheated steam; when the heat user needs saturated steam, the flow rate of the auxiliary steam is reduced to ensure that the steam on the user side is saturated steam.
[0016] The present invention has the following beneficial effects:
[0017] When the system for wet state water atomization recovery of supercritical units in thermal power plants described in the present invention is specifically operated, the wet state water in the water storage tank of the boiler start-up separator is sprayed out in the form of atomized water droplets by the atomizing nozzle, and then heated by the auxiliary steam to become superheated steam or saturated steam, and finally sent to the heat user, so as to realize the full recovery and utilization of high-energy wet state water. The recovery and utilization difficulty is relatively low, the structure is simple, the operation is convenient, and it is convenient for popularization and application. Brief Description of the Drawings
[0018] Figure 1 is a schematic structural diagram of the present invention;
[0019] Figure 2 is a schematic structural diagram of the wet-state water conversion device 8 in the present invention.
[0020] Among them, 1 is the water storage tank of the boiler start-up separator, 2 is the wet-state water measuring instrument, 3 is the wet-state water temperature measuring instrument, 4 is the flow measuring instrument, 5 is the shut-off valve, 6 is the flow control valve, 7 is the manual valve, 8 is the wet-state water conversion device, 9 is the safety valve, 10 is the converted steam pressure measuring instrument, 11 is the converted steam temperature measuring instrument, 12 is the auxiliary steam pipeline, 13 is the auxiliary steam heating device, and 14 is the atomizing nozzle. Specific embodiments
[0021] The present invention will be further described in detail below with reference to the accompanying drawings:
[0022] Refer to Figure 1 and Figure 2 , the system for wet-state water atomization recovery in a supercritical unit of a thermal power plant according to the present invention includes a wet-state water conversion device 8, an auxiliary steam pipeline 12, a water storage tank 1 of a boiler start-up separator, a shut-off valve 5, a flow control valve 6 and a manual valve 7; the wet-state water conversion device 8 includes an auxiliary steam pipeline 12, a housing and an auxiliary steam heating device 13 and an atomizing nozzle 14 arranged in the housing. Among them, the auxiliary steam pipeline 12 is connected to the inlet of the auxiliary steam heating device 13, the auxiliary steam heating device 13 is installed on the front side of the atomizing nozzle 14, and the air flow direction output by the auxiliary steam heating device 13 points to the nozzle of the atomizing nozzle 14. The outlet of the water storage tank 1 of the boiler start-up separator is connected to the inlet of the atomizing nozzle 14 through the shut-off valve 5, the flow control valve 6 and the manual valve 7, and the outlet of the housing is connected to a heat user.
[0023] A wet-state water pressure measuring instrument 2, a wet-state water temperature measuring instrument 3 and a flow measuring instrument 4 are arranged on the pipeline between the outlet of the water storage tank 1 of the boiler start-up separator and the shut-off valve 5; a converted steam temperature measuring instrument 11 and a converted steam pressure measuring instrument 10 are arranged on the pipeline between the housing and the heat user. The present invention further includes a host computer. Among them, the host computer is connected to the wet-state water measuring instrument 2, the wet-state water temperature measuring instrument 3, the flow measuring instrument 4, the converted steam temperature measuring instrument 11, the converted steam pressure measuring instrument 10, the shut-off valve 5 and the flow control valve 6; a safety valve 9 is arranged on the pipeline between the housing and the heat user.
[0024] The form, quantity and layout of the atomizing nozzles 14 are selected according to the flow rate and atomizing requirements of the wet state water; the nozzles on the atomizing nozzles 14 are evenly arranged in a matrix or evenly arranged circumferentially; auxiliary steam is introduced into the auxiliary steam pipeline 12 to heat the atomizing steam, and the heated atomizing steam is wet steam or superheated steam.
[0025] The specific working process of the present invention is as follows:
[0026] After the boiler switches to the wet state operation, wet state water will be generated in the start-up separator of the boiler. When the amount of wet state water reaches the preset amount, the water in the water storage tank 1 of the boiler start-up separator is detected for water pressure by the wet state water pressure measuring instrument 2, the water temperature is detected by the wet state water temperature measuring instrument 3, and the flow rate is detected by the flow measuring instrument 4, and then enters the wet state water conversion device 8 through the shut-off valve 5, the flow control valve 6 and the manual valve 7. Among them, the wet state water is decompressed and flow-controlled through the flow control valve 6. In the wet state water conversion device 8, the wet state water is heated by auxiliary steam into superheated steam or wet steam, and then the pressure is measured by the converted steam pressure measuring instrument 10 and the temperature is measured by the converted steam temperature measuring instrument 11 and then sent to the heat user. In the wet state water conversion device 8, according to the flow rate of the wet state water to be consumed and the requirements on the user side, the size, form, quantity and layout of the atomizing nozzles 14 are set. The atomizing nozzles 14 can be arranged in a shell in a downstream or annular manner. Through the atomizing nozzles 14, the wet state water can be atomized into saturated steam containing atomized water droplets with a size of 20 μm to 500 μm. The auxiliary steam is arranged behind the atomizing nozzles 14 and is used to carry and heat the atomized water droplets formed after the nozzles. The atomized steam is heated by the auxiliary steam into wet steam or superheated steam, depending on the requirements on the user side. The quality of the superheated steam is monitored through the pressure measuring point and the temperature measuring point after the wet state water recovery device. When the heat user needs superheated steam, the flow rate of the auxiliary steam is increased to ensure that the steam on the user side is superheated steam; when the heat user needs saturated steam, the flow rate of the auxiliary steam can be appropriately reduced to control the saturated steam to operate at a certain humidity.
[0027] Embodiment 1
[0028] A certain supercritical 350 MW unit in a power plant was simulated with ebsilon. When the unit was deep peak-shaved to operate at 20% of the rated load (70 MW), the boiler switched to the wet state operation. The boiler start-up separator generated 90 t / h of wet state water with a pressure of 8 MPa and a temperature of 295 °C. After passing through the above-mentioned wet state water recovery system and being heated with a certain amount of auxiliary steam, it was converted into saturated steam and supplied to the heat user. The state of the saturated steam was 0.8 MPa, the temperature was 170.4 °C, and the humidity was 0.3. All the wet state water was converted into wet saturated steam and supplied to the heat user through this system, realizing the full recovery and utilization of the wet state water.
[0029] By calculation, at 20% rated load, when all 90t of high-energy drain water is discharged into the condenser, the heat rate of the unit is approximately 10068 kJ / (kWh), and the coal consumption rate for power generation is approximately 377.2 g / (kWh). After the recovery and transformation, all the saturated steam is recovered to the heat users, and the calculation is carried out using the algorithm of "benefits returned to power generation". Considering a certain loss, the heat rate of the unit can be obtained as 8670 kJ / (kWh), and the coal consumption rate for power generation after transformation is 324.8 g / (kWh). It can be seen that after the transformation, the heat rate of the unit decreases by 1398 kJ / (kWh), and the coal consumption rate for power generation decreases by 52.4 g / (kWh), significantly improving the economy of the unit.
Claims
1. A system for wet water atomization recovery of supercritical units in thermal power plants, characterized in that: It includes a wet water conversion device (8), an auxiliary steam pipeline (12), a boiler startup separator water storage tank (1), a shut-off valve (5), a flow control valve (6) and a manual valve (7); The wet water conversion device (8) comprises an auxiliary steam pipe (12), a shell, and an auxiliary steam heating device (13) and an atomizing nozzle (14) arranged in the shell, wherein the auxiliary steam pipe (12) is connected to the inlet of the auxiliary steam heating device (13), the auxiliary steam heating device (13) is installed on the front side of the atomizing nozzle (14), and the air flow direction output by the auxiliary steam heating device (13) points to the nozzle of the atomizing nozzle (14), the outlet of the boiler startup separator water storage tank (1) is connected to the inlet of the atomizing nozzle (14) via the shut-off valve (5), the flow control valve (6) and the manual valve (7), and the outlet of the shell is connected to the heat user; A wet water measuring instrument (2), a wet water temperature measuring instrument (3) and a flow measuring instrument (4) are provided on a pipeline between the outlet of the boiler startup separator water storage tank (1) and the shut-off valve (5); A reformed steam temperature measuring instrument (11) and a reformed steam pressure measuring instrument (10) are provided on the pipeline between the shell and the heat user; During operation, after the boiler switches to wet state operation, wet water is generated in the boiler startup separator. When the amount of wet water reaches a preset amount, the wet water in the boiler startup separator water storage tank (1) is tested for water pressure by a wet water pressure measuring instrument (2), tested for water temperature by a wet water temperature measuring instrument (3), tested for flow by a flow measuring instrument (4), and then enters the wet water conversion device (8) through a shut-off valve (5), a flow control valve (6) and a manual valve (7). In the wet water conversion device (8), the wet water is sprayed out in the form of atomized water droplets through an atomizing nozzle (14), and then heated to superheated steam or saturated steam by auxiliary steam. Finally, the pressure is measured by a conversion steam pressure measuring instrument (10), and the temperature is measured by a conversion steam temperature measuring instrument (11) before being sent to a heat user. When the heat user needs superheated steam, the flow rate of auxiliary steam is increased to ensure that the steam on the user side is superheated steam; when the heat user needs saturated steam, the flow rate of auxiliary steam is reduced to ensure that the steam on the user side is saturated steam.
2. The system for wet water atomization recovery of supercritical units in thermal power plants according to claim 1, characterized in that: It also includes a host computer, where The host computer is connected to a wet water pressure measuring instrument (2), a wet water temperature measuring instrument (3), a flow measuring instrument (4), a conversion steam temperature measuring instrument (11), a conversion steam pressure measuring instrument (10), a shutoff valve (5), and a flow control valve (6).
3. The system for wet water atomization recovery of supercritical units in thermal power plants according to claim 1, characterized in that: A safety door (9) is provided on the pipeline between the shell and the heat user.
4. The system for wet water atomization recovery of supercritical units in thermal power plants according to claim 1, characterized in that: The form, quantity and layout of the atomizing nozzles (14) are selected according to the flow rate of wet water and the atomization requirements.
5. The system for wet water atomization recovery of supercritical units in thermal power plants according to claim 1, characterized in that: The nozzles on the atomizing nozzle (14) are evenly arranged in a formation or evenly arranged along the circumference.
6. The system for wet water atomization recovery of supercritical units in thermal power plants according to claim 1, characterized in that: The steam introduced into the auxiliary steam pipe (12) is used to heat the atomizing steam, and the heated steam is wet steam or superheated steam.