Boiler feed water pressure reducing and steam temperature reducing device

Abstract

The utility model belongs to the field of boiler steam treatment technology discloses a kind of boiler feed water pressure reduction and steam desuperheating device, comprising: boiler feed water unit, the boiler feed water unit includes feed water output end one and feed water output end two, the feed water output end one is connected to boiler;With the temperature reducing pressure reducing device connected to boiler to process boiler steam, the water supply of feed water output end two is as the temperature reducing water one of temperature reducing pressure reducing device;And with the feed water output end two parallel connection access temperature reducing pressure reducing device's medium-pressure temperature reducing water conveying unit.The utility model provides medium-pressure temperature reducing water by increasing medium-pressure temperature reducing water conveying unit, can be realized when low flow steam temperature controllable, improve the quality of steam, and by with the temperature reducing water cooperation of boiler feed water, different temperature reducing water can be switched according to different pressure conditions, indirectly increase the power generation of cogeneration in power generation steam turbine.

Description

Technical Field

[0001] This utility model belongs to the field of boiler steam treatment technology, specifically relating to a boiler feedwater pressure reduction and steam de-heating device. Background Technology

[0002] In the steam side of a combined heat and power (CHP) system in an industrial boiler or power plant boiler system, the steam supplied by the boiler is mainly treated by a desuperheating and pressure reducing station. During this treatment process, desuperheating water is used in conjunction with the steam treatment. In existing technology, the desuperheating water is typically a portion of the water from the boiler feedwater pump after deaeration by a high-pressure deaerator. This water is supplied to the desuperheating and pressure reducing station for steam treatment. However, because the boiler feedwater pump outlet is usually designed with high pressure and a large head margin, the opening of the regulating valve for boiler drum water level control is small, resulting in significant throttling losses. Furthermore, the feedwater pump operates at a constant speed, and when the downstream system load changes, the feedwater pump speed remains constant, leading to a situation where the feedwater pump motor is overpowered and underutilized, wasting a large amount of electrical energy. Simultaneously, the desuperheating water used by each desuperheater and pressure reducing station comes from the boiler feedwater, making it difficult to control the medium and low-pressure steam temperature at the desuperheater and pressure reducing station outlet, especially at low loads where water often accumulates. Utility Model Content

[0003] In view of this, the purpose of this utility model is to provide a boiler feedwater depressurization and steam desuperheating device to solve the problem of difficulty in controlling the outlet medium and low pressure steam temperature caused by the use of boiler feedwater in the desuperheating and pressure reducing station of the existing boiler system.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A boiler feedwater pressure reduction and steam desuperheating device, comprising: A boiler feedwater unit, comprising a feedwater output terminal one and a feedwater output terminal two, wherein the feedwater output terminal one is connected to the boiler. A desuperheating and pressure-reducing device connected to a boiler for treating boiler steam; the water supplied from the second water supply terminal serves as the desuperheating water for the desuperheating and pressure-reducing device; and A medium-pressure desuperheating water conveying unit is connected in parallel with the second water supply output terminal to the desuperheating and pressure reducing device. The medium-pressure desuperheating water provided by the medium-pressure desuperheating water conveying unit is used as the second desuperheating water for steam treatment of the desuperheating and pressure reducing device. The medium-pressure desuperheating water conveying unit is equipped with a valve assembly for controlling the on-off state. The second water supply output terminal is equipped with a second valve assembly, which works in conjunction with the first valve assembly to switch the supply of de-heating water to the de-heating and pressure reducing device.

[0005] In a possible implementation, the de-cooling and de-pressure device includes a main de-cooling and de-pressure unit and several auxiliary de-cooling and de-pressure units arranged sequentially in the processing order, with the auxiliary de-cooling and de-pressure units connected in parallel with the main de-cooling and de-pressure unit; The medium-pressure desuperheating water conveying unit includes a main desuperheating water conveying line, a first desuperheating water conveying branch line, and a second desuperheating water conveying branch line. The second water supply output terminal includes a first water supply pipeline and a second water supply pipeline. The first water supply pipeline and the first desuperheating water conveying branch line are connected in parallel to the main desuperheating and pressure reducing unit. The second desuperheating water conveying branch line and the second water supply pipeline are connected in parallel to each auxiliary desuperheating and pressure reducing unit.

[0006] In a possible implementation, the valve assembly one includes a control valve one and a control valve two, wherein the control valve one is disposed on the desuperheating water conveying branch one and the control valve two is disposed on the desuperheating water conveying branch two. The valve assembly two includes a control valve three and a control valve four. The control valve three is located on the water supply pipeline one, and the control valve four is located on the water supply pipeline two. The medium-pressure desuperheating water conveying unit also includes a pressure detection device installed on the main desuperheating water conveying line. The pressure detection device, control valve three, and control valve four are simultaneously connected to the controller and form a pressure interlock control through the controller.

[0007] In a possible implementation, the boiler feedwater unit includes a high-pressure deaerator and multiple feedwater pumps connected in parallel to the high-pressure deaerator. The output ends of the multiple feedwater pumps are connected to a main feedwater pipe, which has a feedwater output end one and a feedwater output end two. The outlet pressure of the feedwater pump is 11-13 MPa, and at least one feedwater pump is equipped with a frequency converter.

[0008] In a possible implementation, the medium-pressure desuperheating water delivery unit further includes several medium-pressure demineralized water pumps and a demineralized water delivery pipeline, with the several medium-pressure demineralized water pumps connected in parallel to the input end of the demineralized water delivery pipeline.

[0009] In one possible implementation, three medium-pressure demineralized water pumps are provided.

[0010] Compared with the prior art, the present invention has the following beneficial effects: The boiler feedwater depressurization and steam desuperheating device of this utility model provides medium-pressure desuperheating water by adding a medium-pressure desuperheating water delivery unit, which enables controllable steam temperature at low flow rates and improves steam quality. Furthermore, by cooperating with boiler feedwater as desuperheating water, different desuperheating water can be switched according to different pressure conditions, which indirectly increases the power generation of the generator turbine in the combined heat and power generation.

[0011] Furthermore, by configuring the boiler feedwater pump with frequency conversion and pressure reduction, energy savings can be achieved for the feedwater pump, the scouring of valve accessories by the feedwater can be reduced, and the adjustable boiler feedwater pressure and the adjustable desuperheating water of the desuperheater and pressure reducer can be realized. Attached Figure Description

[0012] Figure 1 A schematic diagram of the existing boiler feedwater and desuperheating / pressure reducing water supply system; Figure 2 This is a schematic diagram of a boiler feedwater pressure reduction and steam desuperheating device.

[0013] In the diagram: 1-High-pressure deaerator; 2-Feed water pump; 3-Boiler; 4-Feed water output terminal 1; 5-Feed water output terminal 2; 51-Feed water delivery pipeline 1; 52-Feed water delivery pipeline 2; 53-Control valve 4; 54-Control valve 3; 55-Main control valve 2; 6-Desuperheating and pressure reducing device; 61-Main desuperheating and pressure reducing unit; 62-Auxiliary desuperheating and pressure reducing unit; 7-Medium-pressure desuperheating water delivery unit; 71-Medium-pressure demineralized water pump; 72-Main desuperheating water delivery line; 73-Desuperheating water delivery branch line 1; 74-Desuperheating water delivery branch line 2; 75-Main control valve; 76-Control valve 1; 77-Control valve 2. Detailed Implementation

[0014] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be further described in detail below with reference to specific embodiments.

[0015] In the existing technology, please refer to Figure 1 As shown, the system is designed with four constant-speed feedwater pumps, including three electric constant-speed pumps and one steam-driven feedwater pump. The rated outlet pressure is 15MPa. Under normal full-load conditions, the system operates with three pumps in operation and one on standby. To prevent the lack of a backup pump when one electric constant-speed feedwater pump needs maintenance, an additional electric constant-speed feedwater pump has been added. However, the electric constant-speed feedwater pump itself has the following problems: (1) The steam drum water level control is achieved by changing the opening of the regulating valve for boiler feedwater flow. Due to the high outlet pressure of the feedwater pump and the large head margin, the opening of the feedwater regulating valve is small, resulting in large throttling losses. (2) Due to the large pressure difference across the boiler feedwater valve, internal leakage of the desuperheating water valve frequently occurs during the operation of the pressure reducing station, making it increasingly difficult to control the temperature of steam at each level. Subsequently, a series of technical modifications were made, such as adding a throttling and pressure-reducing orifice plate and installing a pneumatic pressure reducing valve on the desuperheating and pressure reducing device's desuperheating water main pipe. However, after a period of operation, the scouring increased, and the effect gradually diminished. In order to keep the temperature of steam at each level within a controllable range, the staff had to control the desuperheating water volume by reducing the opening of the manual valve before the regulating valve. After long-term use, the internal leakage of the shut-off valve became serious. During the maintenance period, all manual valves need to be replaced. Under the condition of downstream system load adjustment, the operators must repeatedly adjust the opening of the manual shut-off valve to ensure the steam temperature, which seriously affects the operational stability of the device and the safety of the operators. (3) Because the water pump operates at a constant speed, when the load of the downstream system changes, the speed of the water pump remains unchanged, and the water pump motor exhibits the phenomenon of being too large for the small vehicle, which wastes a lot of electrical energy.

[0016] (4) After the system is overhauled, the constant speed pump is started and operated at high pressure, which causes impact and vibration on the high pressure pipeline. Due to the large pressure difference, the high pressure valve often cannot be opened.

[0017] To solve the above technical problems, please refer to Figure 1 and Figure 2 As shown, an embodiment of this application provides a boiler feedwater pressure reduction and steam desuperheating device, comprising: a boiler 3 feedwater unit, the boiler 3 feedwater unit including a feedwater output terminal 4 and a feedwater output terminal 5, the feedwater output terminal 4 being connected to the boiler 3; a desuperheating and pressure reducing device 6 connected to the boiler 3 to process the steam of the boiler 3, the water supplied by the feedwater output terminal 5 serving as desuperheating water 1 for the desuperheating and pressure reducing device 6; and a medium-pressure desuperheating water conveying unit 7 connected in parallel with the feedwater output terminal 5 to the desuperheating and pressure reducing device 6, the medium-pressure desuperheating water conveying unit 7 providing medium-pressure desuperheating water serving as desuperheating water 2 for steam processing of the desuperheating and pressure reducing device 6, the medium-pressure desuperheating water conveying unit 7 being provided with a valve assembly 1 for controlling the on / off state; wherein, the feedwater output terminal 5 is provided with a valve assembly 2, the valve assembly 2 and the valve assembly 1 cooperating to switch the supply of desuperheating water to the desuperheating and pressure reducing device 6.

[0018] The boiler 3 feedwater unit has two water supply outputs: feedwater output terminal 4 and feedwater output terminal 5. Feedwater output terminal 4 is connected to the boiler 3 to supply water to the boiler 3. Feedwater output terminal 5 is connected to the desuperheating and pressure reducing device 6. The desuperheating and pressure reducing device 6 mainly includes several desuperheating and pressure reducing devices. Desuperheating water 1 can be supplied to the desuperheating and pressure reducing device 6 through feedwater output terminal 5. The desuperheating and pressure reducing device 6 can process the steam generated by the boiler 3 through desuperheating water 1. Since the desuperheating water output from boiler feed pump 2 is high-pressure water, it is difficult for the desuperheater and pressure reducer to control the steam temperature, affecting the stable operation of the device and the safety of the operators. Therefore, this problem can be solved by adding a medium-pressure desuperheating water delivery unit 7. The desuperheating water provided by the medium-pressure desuperheating water delivery unit 7 is medium-pressure water, which is more conducive to ensuring the steam quality and improving the controllability and quality of the steam. In this way, the desuperheating water from the medium-pressure desuperheating water delivery unit 7 and the desuperheating water from boiler feed pump 2 can form two water supply lines, and by setting valve assembly 1 and valve assembly 2 on each line, switching can be easily achieved.

[0019] It should be noted that the medium-pressure desuperheating water conveying unit 7 is mainly suitable for steam treatment under medium and small flow rates. When treating high flow rates, it also needs to be treated with desuperheating water supplied by the boiler feed pump 2.

[0020] By adding a medium-pressure desuperheating water delivery unit 7 to provide medium-pressure desuperheating water, the steam temperature can be controlled at low flow rates, improving the quality of the steam. Furthermore, by cooperating with the boiler feedwater as desuperheating water, different desuperheating water can be switched according to different pressure conditions, indirectly increasing the power generation of the generator turbine in the combined heat and power plant.

[0021] In one embodiment, the desuperheating and pressure reducing device 6 includes a main desuperheating and pressure reducing unit 61 and several auxiliary desuperheating and pressure reducing units 62 arranged sequentially in the processing order. The several auxiliary desuperheating and pressure reducing units are connected in parallel with the main desuperheating and pressure reducing unit 61. The medium-pressure desuperheating water conveying unit 7 includes a main desuperheating water conveying line 72, a first desuperheating water conveying branch line 73, and a second desuperheating water conveying branch line 74. The second water supply output terminal 5 includes a first water supply pipeline 51 and a second water supply pipeline 52. The first water supply pipeline 51 and the first desuperheating water conveying branch line 73 are connected in parallel to the main desuperheating and pressure reducing unit 61. The second desuperheating water conveying branch line 74 and the second water supply pipeline 52 are connected in parallel to each auxiliary desuperheating and pressure reducing unit 62.

[0022] The desuperheating and pressure-reducing device 6 is arranged with a main desuperheating and pressure-reducing unit 61 and several auxiliary desuperheating and pressure-reducing units 62 connected in series and in parallel. For this structure, a separate water supply method is adopted, that is, the medium-pressure desuperheating water delivery unit 7 is divided into two paths: one path supplies desuperheating water to the main desuperheating and pressure-reducing unit 61, and the other path supplies desuperheating water to each auxiliary desuperheating and pressure-reducing unit 62. This provides desuperheating water to each desuperheater and pressure reducer of the desuperheating and pressure-reducing device 6. In this way, a desuperheating water supply structure that can be switched in parallel with the desuperheating water output from the boiler feedwater pump 2 can be formed.

[0023] Based on this, in order to enable automatic switching between the desuperheating water II supplied by the medium-pressure desuperheating water delivery unit 7 and the desuperheating water I supplied by the boiler feedwater 3, the valve assembly I includes control valve I 76 and control valve II 77. Control valve I 76 is located on the desuperheating water delivery branch 1 73, and control valve II 77 is located on the desuperheating water delivery branch 2 74. The valve assembly II includes control valve III 54 and control valve IV 53. Control valve III 54 is located on the feedwater delivery pipeline 1 51, and control valve IV 53 is located on the feedwater delivery pipeline 2 52. The medium-pressure desuperheating water delivery unit 7 also includes a pressure detection device located on the desuperheating water delivery main pipeline 72. The pressure detection device, control valve III 54, and control valve IV 53 are all connected to a controller and form a pressure interlock control through the controller. In this way, when the incoming desuperheating water from the medium-pressure desuperheating water delivery unit 7 is detected and reaches the preset pressure, the controller controls the shut-off of the boiler feedwater delivery pipeline 1 51 and the feedwater delivery pipeline 2 52 via control valve 3 54 and control valve 4 53, and opens control valve 1 76 and control valve 2 77, thereby switching the desuperheating water supply from the boiler 3 feedwater to the medium-pressure desuperheating water delivery unit 7. The controller can switch according to the preset pressure value. For example, when the incoming water pressure of the medium-pressure desuperheating water delivery unit 7 is less than or equal to 5.5 MPa, it indicates that the incoming water or pressure is not suitable, and the system switches to boiler 3 feedwater. When the incoming water pressure is greater than 5.5 MPa, it indicates that the desuperheating water needs to be switched, and the system switches to the medium-pressure desuperheating water delivery unit 7.

[0024] The switching method adopts the pressure interlocking method described above, that is, it can only be opened when the preset pressure condition is met. In other words, the incoming water pressure of each switching pipeline is detected by pressure detection. When the incoming water of the medium-pressure desuperheating water delivery unit 7 is detected and the corresponding preset pressure is met, valve assembly 2 is closed and valve assembly 1 is opened, realizing the switch to the desuperheating water supply of the medium-pressure desuperheating water delivery unit 7. When the incoming water of the water supply output terminal 4 is detected and the corresponding preset pressure is met, valve assembly 1 is closed and valve assembly 2 is opened, realizing the switch to the desuperheating water supply of the boiler 3 feed water unit. This facilitates the switching of desuperheating water.

[0025] Preferably, the main desuperheating water supply line 72 is equipped with a main control valve 75, which controls the upstream valves of control valve 76 and control valve 77, and is connected to a controller. The controller mainly works in conjunction with the main control valve 75. Simultaneously, a main control valve 55 is provided at the common input end of each water supply pipeline 52, which is also connected to the controller for more convenient and rapid on / off control, thereby facilitating better pipeline switching.

[0026] Because excessive pressure in the boiler 3 feedwater pump 2 can cause inconvenience in steam processing, scour of valves and other accessories, and is also detrimental to the energy saving of the feedwater pump 2, in order to solve this problem, in the embodiments of this application, the boiler 3 feedwater unit includes a high-pressure deaerator 1 and multiple feedwater pumps 2 connected in parallel to the high-pressure deaerator 1. The output ends of the multiple feedwater pumps 2 are connected to a main pipeline. The main pipeline has a feedwater output end 4 and a feedwater output end 5. The outlet pressure of the feedwater pump 2 is 11-13 MPa, and at least one feedwater pump 2 is equipped with a frequency converter.

[0027] Among them, the high-pressure deaerator 1 can deaerate and filter the feedwater of boiler 3. The high-pressure deaerator 1 is not improved. Instead, the feedwater pump 2 adopts a lower pressure feedwater pump 2, and at least one of the feedwater pump 2 is equipped with a frequency converter. The frequency conversion speed regulation system is connected to the main power supply system with a voltage level of 10kV for frequency conversion speed regulation of the motor. The remaining feedwater pump 2 are purchased separately, and feedwater pump 2 with a lower design outlet pressure is purchased. Preferably, there are four feedwater pump 2 in total. One feedwater pump 2 is equipped with a frequency converter, and the other three are purchased separately with a design outlet pressure of 12.5MPa and a flow rate of 185m3 / h. In this way, it is feasible to reduce the feed water pressure of boiler 3 by adding a frequency converter, so as to achieve low pressure difference (about 2.5MPa) for water supply to boiler 3, with good energy saving effect; it is also feasible to reduce the feed water pressure of boiler 3 by replacing the feed water pump 2 of boiler 3, so as to achieve low pressure difference (about 2.5MPa) for water supply to boiler 3, with good node effect. At the same time, the pressure is reduced by adding a medium pressure desuperheating water delivery unit 7, so that the desuperheating and pressure reducing device 6 can operate stably at a small flow rate.

[0028] In the specific implementation process, the medium-pressure desuperheating water delivery unit 7 also includes several medium-pressure demineralized water pumps 71 and demineralized water delivery pipelines. The medium-pressure demineralized water pumps 71 are connected in parallel to the input end of the demineralized water delivery pipelines. Preferably, three medium-pressure demineralized water pumps 71 are used, with a demineralized water pressure of 7.0 MPa and a temperature of 104℃. The pipelines are re-laid so that the medium-pressure demineralized water, serving as desuperheating water II, is distributed in two routes to the main desuperheating and pressure reducing unit 61 and the auxiliary desuperheating and pressure reducing unit 62. Valves, pressure measuring points, and flow measuring points are installed on the main desuperheating water delivery route 72, the first desuperheating water delivery branch route 73, and the second desuperheating water delivery branch route 74. The demineralized water delivery pipeline includes the main desuperheating water delivery route 72, the first desuperheating water delivery branch route 73, and the second desuperheating water delivery branch route 74.

[0029] Specifically, three medium-pressure demineralized water pumps 71 are provided.

[0030] In addition, corresponding basic piping and accessories can be installed on each pipeline, such as backup piping, pressure relief valves, pneumatic shut-off valves, safety valves, pressure gauges, and other devices. Figure 1 and Figure 2 This is a simplified structural diagram.

[0031] The above are merely preferred embodiments of this utility model. It should be noted that the above preferred embodiments should not be considered as limitations on this utility model, and the scope of protection of this utility model should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model.

Claims

1. A boiler feedwater pressure reduction and steam desuperheating device, characterized in that, include: The boiler (3) water supply unit includes a water supply output terminal one (4) and a water supply output terminal two (5), and the water supply output terminal one (4) is connected to the boiler (3). A desuperheating and pressure-reducing device (6) connected to a boiler (3) to process the steam of the boiler (3), wherein the water supplied from the second water supply terminal (5) serves as the desuperheating water for the desuperheating and pressure-reducing device (6); and A medium-pressure desuperheating water conveying unit (7) is connected in parallel with the water supply output terminal 2 (5) to the desuperheating and pressure reducing device (6). The medium-pressure desuperheating water provided by the medium-pressure desuperheating water conveying unit (7) is used as the desuperheating water 2 for steam treatment of the desuperheating and pressure reducing device (6). The medium-pressure desuperheating water conveying unit (7) is provided with a valve assembly 1 for controlling the on and off. Among them, valve assembly two is provided on the water supply output end two (5), and valve assembly two and valve assembly one cooperate to switch the water supply of the de-heating water of the de-heating and pressure reducing device (6).

2. The boiler feedwater pressure reduction and steam desuperheating device as described in claim 1, characterized in that, The de-cooling and pressure reducing device (6) includes a main de-cooling and pressure reducing unit (61) and several auxiliary de-cooling and pressure reducing units (62) arranged in sequence according to the processing order. Several of the auxiliary de-cooling and pressure reducing units (62) are connected in parallel with the main de-cooling and pressure reducing unit (61). The medium-pressure desuperheating water conveying unit (7) includes a desuperheating water conveying main line (72), a desuperheating water conveying branch line one (73) and a desuperheating water conveying branch line two (74). The water supply output end two (5) includes a water supply conveying pipeline one (51) and a water supply conveying pipeline two (52). The water supply conveying pipeline one (51) and the desuperheating water conveying branch line one (73) are connected in parallel to the main desuperheating and pressure reducing unit (61). The desuperheating water conveying branch line two (74) and the water supply conveying pipeline two (52) are connected in parallel to each auxiliary desuperheating and pressure reducing unit (62).

3. The boiler feedwater pressure reduction and steam desuperheating device as described in claim 2, characterized in that, The valve assembly includes a control valve (76) and a control valve (77). The control valve (76) is located on the first branch (73) of the desuperheating water supply line, and the control valve (77) is located on the second branch (74) of the desuperheating water supply line. The valve assembly two includes a control valve three (54) and a control valve four (53). The control valve three (54) is located on the water supply pipeline one (51), and the control valve four (53) is located on the water supply pipeline two (52). The medium-pressure desuperheating water conveying unit (7) also includes a pressure detection device installed on the desuperheating water conveying main line (72). The pressure detection device, control valve three (54) and control valve four (53) are connected to the controller and form a pressure interlock control through the controller.

4. The boiler feedwater pressure reduction and steam desuperheating device as described in claim 1, characterized in that, The boiler (3) feedwater unit includes a high-pressure deaerator (1) and multiple feedwater pumps (2) connected in parallel to the high-pressure deaerator (1). The output ends of the multiple feedwater pumps (2) are connected to a main pipeline. The main pipeline has a feedwater output end one (4) and a feedwater output end two (5). The outlet pressure of the feedwater pump (2) is 11-13 MPa, and at least one feedwater pump (2) is equipped with a frequency converter.

5. The boiler feedwater pressure reduction and steam desuperheating device as described in claim 1, characterized in that, The medium-pressure desuperheating water delivery unit (7) also includes several medium-pressure demineralized water pumps (71) and a demineralized water pipeline. Several medium-pressure demineralized water pumps (71) are connected in parallel to the input end of the demineralized water pipeline.

6. The boiler feedwater pressure reduction and steam desuperheating device as described in claim 5, characterized in that, Three medium-pressure demineralized water pumps (71) are provided.

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