System and method for increasing boiler feed water temperature during pipe blowing

Abstract

The present invention is a system for increasing the temperature of boiler feed water during pipe blowing and a method for using the system. The system includes a feed water pipeline, a deaerator is arranged on the feed water pipeline, the outlet of the deaerator is connected to a feed water pump, the outlet of the feed water pump is connected to a high-pressure heater group, the outlet of the high-pressure heater group can be connected to the boiler water inlet, the deaerator is connected to an auxiliary steam header, the auxiliary steam header can be connected to a cold re-pipeline or a high-pressure heater group through a cold re-to-auxiliary steam header channel, the high-pressure heater group can be connected to a cold re-pipeline or an auxiliary steam header through a cold re-to-heater channel, the auxiliary steam header can be used to heat the feed water in the deaerator and can be used to heat and heat the feed water passing through the high-pressure heater group. The present invention not only uses the deaerator to heat the feed water, but also leads part of the auxiliary steam in the auxiliary steam header to the high-pressure heater group, thereby reducing the temperature and heat storage of the deaerator, reducing heat loss, and improving heat utilization.

Description

Technical Field

[0001] The invention relates to the technical field of thermal power generation, and in particular to a system for increasing boiler feed water temperature during pipe blowing and a method for using the system. Background Art

[0002] In thermal power generating units, the steam turbine has very high quality requirements for the steam entering it. If there are foreign objects entering the steam turbine, the rotating impeller will be damaged. For newly built units, units involving boiler and steam pipeline modification, in order to remove welding slag, oxide scale, rust and other foreign objects generated during the manufacturing and installation of boilers and steam pipelines, boiler blowdown is required before the steam turbine is flushed. Boiler blowdown is to use the high-temperature and high-pressure steam generated by the boiler to blow the superheater, reheater, main steam pipeline, reheat pipeline, etc. During the blowdown, the boiler needs to be ignited and put into operation. The feed water temperature has a more obvious impact on the operation of the boiler, which is mainly manifested as follows:

[0003] (1) For boilers only, under the same steam parameters, increasing the feed water temperature can reduce fuel input and save fuel;

[0004] (2) Increasing the boiler feed water temperature can reduce the temperature difference of heat exchange and improve the efficiency of the boiler;

[0005] (3) If the boiler feed water temperature is too low, it may cause the boiler superheater and reheater wall temperature to overheat, affecting the safe operation of the boiler.

[0006] Therefore, the boiler feed water temperature should be increased as much as possible before the boiler is filled with water and during normal operation. During the blowdown, the extraction and heat recovery system cannot be put into operation, and the feed water temperature cannot be increased by putting in high and low pressure heaters. The main method currently used is to start the boiler to supply steam to the auxiliary steam header, and then supply steam to the deaerator through the auxiliary steam header to heat the feed water. However, in the actual blowdown process, there are often many constraints in using this method to increase the boiler feed water temperature. For example, the capacity of the start-up boiler equipped with some units is small, and the flow of auxiliary steam is not enough to heat the feed water to a higher temperature; the deaerator is large in size, capacity, and heat storage. Before filling the boiler with water, it takes a long time to heat the deaerator, which slows down the boiler filling time; in order to obtain a higher feed water temperature, it is necessary to increase the steam flow of the auxiliary steam to the deaerator. When the steam flow is high, the deaerator may produce greater vibration, affecting the safety of operation, and before hot flushing, the higher the water temperature inside the deaerator, the easier it is to flush out the debris, which may cause the filter screen at the inlet of the feed water pump to be blocked, and the boiler needs to be stopped for cleaning, delaying the progress of the blowdown work. In response to the above problems, for thermal power plants with two units, adjacent unit heating pipelines are generally designed at present, and the cold re-steam source of the adjacent unit is used to heat a high-pressure heater of this unit through the adjacent unit heating pipeline. However, this system is often not operational for the first unit; there are also a few literature reports that the adjacent unit auxiliary steam is connected to the adjacent unit heating pipeline, and then a certain stage of the local high-pressure heater is heated, but for the newly built first-phase units, the adjacent unit auxiliary steam source also comes from the same startup boiler. Heating the local high-pressure heater through the adjacent unit pipeline is a long way away, the steam pipeline is long, the pipe heating time is long during commissioning, and no external heat source is added, which is not generally applicable.

[0007] Therefore, the inventor, relying on many years of experience and practice in related industries, proposes a system for increasing the boiler feed water temperature during pipe blowing and a method of using the system to overcome the defects of the prior art. Summary of the invention

[0008] The object of the present invention is to provide a system for increasing the boiler feed water temperature during pipe blowing and a method for using the system, which not only uses a deaerator to heat the feed water, but also leads part of the auxiliary steam in the auxiliary steam header to the high-pressure heater group, thereby lowering the deaerator temperature and heat storage, reducing heat loss, and improving heat utilization.

[0009] The objective of the present invention is achieved in this way. A system for increasing the boiler feed water temperature during pipe blowing comprises a feed water pipeline, a deaerator is arranged on the feed water pipeline, the outlet of the deaerator is connected to a feed water pump, the outlet of the feed water pump is connected to a high-pressure heater group, the outlet of the high-pressure heater group can be connected to the boiler water inlet, the deaerator is connected to an auxiliary steam manifold, the auxiliary steam manifold can be connected to a cold re-pipeline or a high-pressure heater group through a cold re-to-auxiliary steam manifold channel, the high-pressure heater group can be connected to a cold re-pipeline or an auxiliary steam manifold through a cold re-to-heater channel, the auxiliary steam manifold can be used to heat the feed water in the deaerator and can be used to heat and increase the temperature of the feed water passing through the high-pressure heater group.

[0010] In a preferred embodiment of the present invention, the high-pressure heater group includes a first high-pressure heater, a second high-pressure heater and a third high-pressure heater sequentially connected in series to the water supply pipe, the first high-pressure heater can be connected to the boiler water inlet, the third high-pressure heater is connected to the water supply pump, and the cold-to-auxiliary steam manifold channel and the cold-to-heater channel can connect the auxiliary steam manifold and the second high-pressure heater.

[0011] In a preferred embodiment of the present invention, a drain outlet is provided on the second high-pressure heater, and the drain outlet can be connected to the deaerator through a drain pipeline.

[0012] In a preferred embodiment of the present invention, a connecting pipe is detachably provided between the cold-return-to-auxiliary-steam-manifold passage and the cold-return-to-heater passage, and a first check valve is detachably provided between the cold-return-to-auxiliary-steam-manifold passage and the cold-return pipeline.

[0013] In a preferred embodiment of the present invention, a first header connection port and a second header connection port are provided on the auxiliary steam header, the first header connection port can be connected to the deaerator, and the second header connection port can be connected to the cold re-to-auxiliary steam header passage.

[0014] In a preferred embodiment of the present invention, a first regulating valve is provided on the passage from the cold refueling to the auxiliary steam manifold, and the first regulating valve is used to regulate the flow rate of high-temperature steam from the auxiliary steam manifold to the second high-pressure heater; a first manual stop valve is connected between the first regulating valve and the second manifold connection port, and a first electric stop valve is connected between the first regulating valve and the connecting pipe.

[0015] In a preferred embodiment of the present invention, a second check valve and a second electric stop valve are sequentially connected between the connecting pipe and the second high-pressure heater.

[0016] In a preferred embodiment of the present invention, a fourth electric stop valve, a third regulating valve and a third check valve are sequentially connected between the first header connection port and the deaerator, and the third regulating valve is used to adjust the high-temperature steam flow from the auxiliary steam header to the deaerator.

[0017] In a preferred embodiment of the present invention, a third electric stop valve, a second regulating valve and a second manual valve are sequentially arranged on the drain pipeline from the drain outlet, and the second regulating valve is used to adjust the water level of the second high-pressure heater.

[0018] The object of the present invention can also be achieved in that the method for using the system for increasing the boiler feed water temperature during pipe blowing comprises the following steps:

[0019] Step a, assembling a system for increasing boiler feed water temperature during blowpipe;

[0020] Step b, during normal operation of the unit, the cold recirculation to auxiliary steam header channel and the cold recirculation to heater channel are both connected to the cold recirculation pipeline, and high-temperature steam is supplied to the high-pressure heater group and the auxiliary steam header respectively;

[0021] During step c, pipe blowing, the auxiliary steam header is connected to the deaerator and the second high-pressure heater respectively, and the drain pipeline is connected. The high-temperature steam entering the deaerator is directly mixed with the feed water to heat it. After the feed water in the deaerator is pressurized by the feed water pump, it passes through the third high-pressure heater, the second high-pressure heater and the first high-pressure heater in sequence. The high-temperature steam entering the second high-pressure heater heats the feed water from the deaerator again, and the feed water enters the boiler after being heated; the drain from the second high-pressure heater returns to the deaerator through the drain pipeline.

[0022] As described above, the system for increasing boiler feed water temperature during pipe blowing provided by the present invention and the method for using the system have the following beneficial effects:

[0023] The system for increasing the boiler feed water temperature during pipe blowing provided by the present invention and the method for using the system not only use the deaerator to heat the feed water, but also lead part of the auxiliary steam in the auxiliary steam header to the high-pressure heater group. Under the condition of the same auxiliary steam flow rate, the flow rate of the auxiliary steam used by the deaerator is reduced. Compared with the method of using only the deaerator to heat the feed water, the deaerator temperature and heat storage are reduced, the heat loss is reduced, the heat utilization rate is improved, and the boiler feed water temperature is increased more quickly, and the boiler water filling is accelerated; the auxiliary steam utilization flow rate can be increased, and the stability and safety of the deaerator operation can be guaranteed while the feed water temperature is increased; due to the increase in the feed water temperature, it is beneficial to control the main reheat steam temperature, increase the safety of boiler operation, and at the same time increase the boiler efficiency and save part of the fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The following drawings are intended only to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0025] Figure 1 : Schematic diagram of a system for increasing boiler feed water temperature during pipe blowing according to the present invention.

[0026] Figure 2 : It is a schematic diagram of the connection status of the auxiliary steam header and the second high-pressure heater of the present invention during normal operation of the unit.

[0027] Figure 3 : It is a schematic diagram of the connection status of the auxiliary steam manifold and the second high-pressure heater of the present invention during blowing.

[0028] In the figure:

[0029] 100. A system for increasing boiler feed water temperature during pipe blowing;

[0030] 1. Water supply pipeline;

[0031] 2. Deaerator;

[0032] 3. Water supply pump;

[0033] 4. High-voltage heater group; 41. First high-voltage heater; 42. Second high-voltage heater; 43. Third high-voltage heater;

[0034] 5. Auxiliary steam header; 51. First header connection port; 52. Second header connection port;

[0035] 61. Channel from cold to auxiliary steam header; 62. Channel from cold to heater; 63. Connecting pipe; 64. First check valve; 65. First regulating valve; 66. First manual stop valve; 67. First electric stop valve; 68. Second check valve; 69. Second electric stop valve;

[0036] 7. Drain pipe; 71. Third electric stop valve; 72. Second regulating valve; 73. Second manual valve;

[0037] 81. Fourth electric stop door; 82. Third regulating valve; 83. Third check valve;

[0038] 9. Boiler; 91. Boiler water inlet; 92. Cold recirculation pipe. DETAILED DESCRIPTION

[0039] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0040] The specific embodiments of the present invention described herein are only used to explain the purpose of the present invention and cannot be understood as limiting the present invention in any way. Under the guidance of the present invention, technicians can conceive of any possible variations based on the present invention, which should be considered to belong to the scope of the present invention. It should be noted that when an element is referred to as "arranged on" another element, it can be directly on the other element or there can also be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a central element at the same time. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, or it can be the internal communication of two elements, it can be directly connected, or it can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and do not represent the only implementation method.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0042] like Figures 1 to 3 As shown, the present invention provides a system 100 for increasing the boiler feed water temperature during pipe blowing, comprising a feed water pipeline 1, a deaerator 2 is arranged on the feed water pipeline 1, the outlet of the deaerator 2 is connected to a feed water pump 3, the outlet of the feed water pump 3 is connected to a high-pressure heater group 4, the outlet of the high-pressure heater group 4 can be connected to a boiler water inlet 91 (existing technology), the deaerator 2 is connected to an auxiliary steam header 5 (auxiliary steam is high-temperature steam, which can exchange heat with feed water to increase its temperature), the auxiliary steam header 5 can be connected to a cold re-pipeline 92 (existing technology, the high-temperature steam generated by the boiler flows through the cold re-pipeline) or the high-pressure heater group 4 through a cold re-to-auxiliary steam header channel 61, the high-pressure heater group 4 can be connected to the cold re-pipeline 92 or the auxiliary steam header 5 through a cold re-to-heater channel 62, the auxiliary steam header 5 can be used to heat the feed water in the deaerator and can be used to heat and increase the temperature of the feed water passing through the high-pressure heater group 4.

[0043] During normal operation of the unit, if Figure 2 As shown, the cold recirculation to auxiliary steam header channel 61 and the cold recirculation to heater channel 62 are both connected to the cold recirculation pipeline 92 and are relatively close to each other; high-temperature steam is supplied to the high-pressure heater group 4 and the auxiliary steam header 5 respectively; Figure 3As shown, during unit commissioning and boiler blowdown, the cold recirculation pipe 92 needs to be purged with the high-temperature steam generated by the boiler 9. At this time, the cold recirculation to auxiliary steam header channel 61 and the cold recirculation to heater channel 62 are disconnected from the cold recirculation pipe 92. The cold recirculation to auxiliary steam header channel 61 and the cold recirculation to heater channel 62 are connected, and the high-temperature steam in the auxiliary steam header 5 can be led to the high-pressure heater group 4. At this time, the high-temperature steam in the auxiliary steam header 5 comes from other heat sources, such as a start-up boiler, an adjacent unit, etc.

[0044] The system for increasing the boiler feed water temperature during pipe blowing provided by the present invention not only uses a deaerator to heat the feed water, but also guides part of the auxiliary steam in the auxiliary steam header to the high-pressure heater group. Under the condition of the same auxiliary steam flow rate, the flow rate of the auxiliary steam utilized by the deaerator is reduced. Compared with the method of using only a deaerator to heat the feed water, the deaerator temperature and heat storage are reduced, the heat loss is reduced, the heat utilization rate is improved, and the boiler feed water temperature is increased more quickly, and the boiler water filling is accelerated; the auxiliary steam utilization flow rate can be increased, and the stability and safety of the deaerator operation can be guaranteed while the feed water temperature is increased; due to the increase in the feed water temperature, it is beneficial to control the main reheat steam temperature, increase the safety of boiler operation, and at the same time increase the boiler efficiency and save part of the fuel.

[0045] Further, if Figure 1 As shown, the high-pressure heater group 4 includes a first high-pressure heater 41, a second high-pressure heater 42 and a third high-pressure heater 43 which are sequentially connected in series to the feed water pipeline 1. The first high-pressure heater 41 can be connected to the boiler water inlet, the third high-pressure heater 43 is connected to the feed water pump 3, and the cold-to-auxiliary steam header channel 61 and the cold-to-heater channel 62 can connect the auxiliary steam header 5 and the second high-pressure heater 42. The cold-to-auxiliary steam header channel 61 and the cold-to-heater channel 62 can lead part of the auxiliary steam to the second high-pressure heater 42 to heat the feed water, and reduce the flow rate of the auxiliary steam used by the deaerator under the condition of the same auxiliary steam flow rate.

[0046] Furthermore, the outer surface of the water supply pipe 1 is covered with thermal insulation material to fully insulate and reduce heat dissipation of the water supply.

[0047] Further, if Figure 1 As shown, the second high-pressure heater 42 is a shell and tube heat exchanger, the boiler feed water flows through the tube side, the high-temperature steam from the auxiliary steam header 5 flows into the shell side, the high-temperature steam heats the boiler feed water in the tube side, does not mix with the boiler feed water, and the high-temperature steam cools down and condenses to form drainage. The second high-pressure heater 42 is provided with a drainage outlet, which can be connected to the deaerator 2 through the drainage pipeline 7, and the drainage enters the deaerator 2 through the drainage pipeline 7 and mixes with the feed water.

[0048] Further, if Figure 1As shown, a connecting pipe 63 is detachably provided between the cold-to-auxiliary steam manifold passage 61 and the cold-to-heater passage 62 , and a first check valve 64 is detachably provided between the cold-to-auxiliary steam manifold passage 61 and the cold-to-duct 92 .

[0049] During the unit commissioning, before the boiler blowdown, in order to prevent the cold re-to-auxiliary steam header channel 61 and the cold re-to-heater channel 62 from entering steam, the cold re-to-auxiliary steam header channel 61 and the cold re-to-heater channel 62 are disconnected and blocked on the cold re-pipeline side; when blowdown is required, the cold re-to-auxiliary steam header channel 61 and the cold re-to-heater channel 62 are connected with a connecting pipe 63, and the auxiliary steam header 5 and the second high-pressure heater 42 are connected, so that the auxiliary steam can heat the feed water in the second high-pressure heater 42. The cold re-to-heater channel 62 is short, the connecting pipe 63 does not need to be too long, and the on-site workload is very small.

[0050] Further, if Figure 1 As shown, the auxiliary steam header 5 is provided with a first header connection port 51 and a second header connection port 52, the first header connection port 51 can be connected to the deaerator 2, and the second header connection port 52 can be connected to the cold to auxiliary steam header channel 61. The outer surface of the connecting pipe 63 is covered with a heat preservation material to fully insulate and reduce heat dissipation.

[0051] Further, if Figure 1 As shown, a first regulating valve 65 is provided on the cold to auxiliary steam header passage 61, and the first regulating valve 65 is used to adjust the flow rate of high-temperature steam from the auxiliary steam header to the second high-pressure heater.

[0052] Further, if Figure 1 As shown, a first manual stop valve 66 is connected between the first regulating valve 65 and the second manifold connection port 52 , and a first electric stop valve 67 is connected between the first regulating valve 65 and the connecting pipe 63 .

[0053] Further, if Figure 1 As shown, a second check valve 68 and a second electric stop valve 69 are sequentially connected between the connecting pipe 63 and the second high-pressure heater 42 .

[0054] Further, if Figure 1 As shown, a fourth electric stop valve 81 , a third regulating valve 82 and a third check valve 83 are sequentially connected between the first header connection port 51 and the deaerator 2 .

[0055] Further, if Figure 1 As shown, a third electric stop valve 71, a second regulating valve 72 and a second manual valve 73 are arranged on the drain pipe 7 in sequence from the drain outlet.

[0056] During actual operation, the first regulating valve 65 and the third regulating valve 82 are used to adjust the steam flow rates entering the second high-pressure heater 42 and the deaerator 2 respectively, and the feed water is heated at the same time; the water level of the second high-pressure heater 42 is adjusted by the second regulating valve 72 to ensure the pressure in the second high-pressure heater 42 so that the drain water can flow smoothly into the deaerator 2.

[0057] The system 100 for increasing boiler feed water temperature during pipe blowing of the present invention includes a feed water process and a steam process, wherein:

[0058] In the water supply process, the feed water in the deaerator 2 is pressurized by the feed water pump 3 , and then further heated and heated by the third high-pressure heater 43 , the second high-pressure heater 42 and the first high-pressure heater 41 in sequence, and then enters the boiler 9 .

[0059] In the steam process (auxiliary steam process), the high-temperature steam is divided into two paths. A part of the high-temperature steam enters the deaerator 2 through the fourth electric stop gate 81, the third regulating valve 82 and the third check valve 83, and is directly mixed with the feed water to heat it. During operation, the fourth electric stop gate 81 is fully opened, and the third check valve 83 is automatically opened under the action of the front and rear pressure difference, and the steam flow entering the deaerator 2 is adjusted by the third regulating valve 82.

[0060] A portion of the high-temperature steam enters the second high-pressure heater 42 through the first manual stop valve 66, the first regulating valve 65, the first electric stop valve 67, the connecting pipe 63, the second check valve 68 and the second electric stop valve 69, and the high-temperature steam indirectly heats the feed water. The condensed drain enters the deaerator 2 and mixes with the feed water through the drain pipeline 7, the third electric stop valve 71, the second regulating valve 72 and the second manual valve 73. During operation, the first manual stop valve 66, the first electric stop valve 67 and the second electric stop valve 69 are fully opened, and the flow of high-temperature steam entering the second high-pressure heater 42 is adjusted by the first regulating valve 65; the third electric stop valve 71 and the second manual valve 73 are fully opened, and the drain volume and the water level of the second high-pressure heater 42 are adjusted by the second regulating valve 72.

[0061] The method of using the system 100 of increasing boiler feed water temperature during pipe blowing of the present invention is as follows:

[0062] Step a, assembling a system for increasing boiler feed water temperature during blowpipe;

[0063] Specifically, during the unit commissioning process, before the boiler blowdown, in order to prevent steam from entering the cold re-to-auxiliary steam manifold channel 61 and the cold re-to-heater channel 62, the cold re-to-auxiliary steam manifold channel 61 is disconnected and blocked on the cold re-pipeline side by the first check valve 64, and the cold re-to-heater channel 62 is disconnected and blocked on the cold re-pipeline side by the second check valve 68.

[0064] Step b: Figure 2 As shown, during normal operation of the unit, the cold recirculation to auxiliary steam header channel 61 and the cold recirculation to heater channel 62 are both connected to the cold recirculation pipeline 92 and are relatively close to each other; high-temperature steam is supplied to the high-pressure heater group 4 and the auxiliary steam header 5 respectively;

[0065] Step c: Figure 3 As shown, when blowing is required, the auxiliary steam header is connected to the deaerator and the second high-pressure heater respectively, and the drain pipeline is connected. The high-temperature steam entering the deaerator is directly mixed with the feed water to heat it. After the feed water in the deaerator is pressurized by the feed water pump, it passes through the third high-pressure heater, the second high-pressure heater and the first high-pressure heater in sequence. The high-temperature steam entering the second high-pressure heater heats the feed water from the deaerator again, and the feed water enters the boiler after being heated; the drain of the second high-pressure heater returns to the deaerator through the drain pipeline;

[0066] Specifically, before blowing the pipe, remove the first check valve 64 on the cold-to-auxiliary steam manifold channel 61, connect the cold-to-auxiliary steam manifold channel 61 and the cold-to-heater channel 62 with the connecting pipe 63, and conduct the auxiliary steam manifold 5 and the second high-pressure heater 42, so as to achieve auxiliary steam heating of the feed water in the second high-pressure heater 42.

[0067] The valves (the first manual stop valve 66, the first electric stop valve 67, the second check valve 68, the second electric stop valve 69, the third electric stop valve 71, the second manual valve 73, the fourth electric stop valve 81 and the third check valve 83) are connected, and the high-temperature steam in the auxiliary steam manifold 5 flows to the second high-pressure heater 42 and the deaerator 2 respectively. The high-temperature steam entering the deaerator 2 is directly mixed with the feed water to heat it. After the feed water in the deaerator 2 is pressurized by the feed water pump 3, it passes through the third high-pressure heater 43, the second high-pressure heater 42 and the first high-pressure heater 41 in sequence. The high-temperature steam entering the second high-pressure heater 42 heats the feed water from the deaerator 2, and the feed water enters the boiler 9 after being heated; the drain of the second high-pressure heater returns to the deaerator through the drain pipeline.

[0068] During the process, the steam flow from the auxiliary steam header 5 to the second high-pressure heater 42 and the deaerator 2 is adjusted by the first regulating valve 65 and the third regulating valve 82 according to demand.

[0069] As described above, the system for increasing boiler feed water temperature during pipe blowing provided by the present invention and the method for using the system have the following beneficial effects:

[0070] The system for increasing the boiler feed water temperature during pipe blowing provided by the present invention and the method for using the system not only use the deaerator to heat the feed water, but also lead part of the auxiliary steam in the auxiliary steam header to the high-pressure heater group. Under the condition of the same auxiliary steam flow rate, the flow rate of the auxiliary steam used by the deaerator is reduced. Compared with the method of using only the deaerator to heat the feed water, the deaerator temperature and heat storage are reduced, the heat loss is reduced, the heat utilization rate is improved, and the boiler feed water temperature is increased more quickly, and the boiler water filling is accelerated; the auxiliary steam utilization flow rate can be increased, and the stability and safety of the deaerator operation can be guaranteed while the feed water temperature is increased; due to the increase in the feed water temperature, it is beneficial to control the main reheat steam temperature, increase the safety of boiler operation, and at the same time increase the boiler efficiency and save part of the fuel.

[0071] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A system for increasing the boiler feed water temperature during pipe blowing, comprising a feed water pipeline, a deaerator is arranged on the feed water pipeline, and an outlet of the deaerator is connected to a feed water pump, characterized in that: The outlet of the feed water pump is connected to the high-pressure heater group, and the outlet of the high-pressure heater group can be connected to the water inlet of the boiler. The deaerator is connected to an auxiliary steam header, and the auxiliary steam header can be connected to the cold re-pipeline or the high-pressure heater group through the cold re-to-auxiliary steam header channel. The high-pressure heater group can be connected to the cold re-pipeline or the auxiliary steam header through the cold re-to-heater channel. The auxiliary steam header can be used to heat the feed water in the deaerator and can be used to heat the feed water passing through the high-pressure heater group; The high-pressure heater group includes a first high-pressure heater, a second high-pressure heater and a third high-pressure heater which are sequentially connected in series to the feedwater pipeline, the first high-pressure heater can be connected to the boiler water inlet, the third high-pressure heater is connected to the feedwater pump, the cold-to-auxiliary steam header channel and the cold-to-heater channel can be connected to the auxiliary steam header and the second high-pressure heater; The second high-pressure heater is provided with a drain outlet, and the drain outlet can be connected to the deaerator through a drain pipeline; A connecting pipe is detachably provided between the cold recirculation to auxiliary steam header passage and the cold recirculation to heater passage, and a first check valve is detachably provided between the cold recirculation to auxiliary steam header passage and the cold recirculation pipeline; A third electric stop valve, a second regulating valve and a second manual valve are sequentially arranged on the drain pipeline from the drain outlet, and the second regulating valve is used to adjust the water level of the second high-pressure heater.

2. A system for increasing boiler feed water temperature during pipe blowing as claimed in claim 1, characterized in that The auxiliary steam header is provided with a first header connection port and a second header connection port, wherein the first header connection port can be communicated with the deaerator, and the second header connection port can be communicated with the cold re-to-auxiliary steam header passage.

3. A system for increasing boiler feed water temperature during pipe blowing as claimed in claim 2, characterized in that: A first regulating valve is provided on the passage from the cold reheat to the auxiliary steam header, and the first regulating valve is used to regulate the flow of high-temperature steam from the auxiliary steam header to the second high-pressure heater; a first manual stop valve is connected between the first regulating valve and the second header connection port, and a first electric stop valve is connected between the first regulating valve and the connecting pipe.

4. The system for increasing boiler feed water temperature during pipe blowing as claimed in claim 1, characterized in that: A second check valve and a second electric stop valve are sequentially connected between the connecting pipe and the second high-pressure heater.

5. The system for increasing boiler feed water temperature during pipe blowing as claimed in claim 2, characterized in that: A fourth electric stop valve, a third regulating valve and a third check valve are sequentially connected between the first header connection port and the deaerator. The third regulating valve is used to adjust the high-temperature steam flow from the auxiliary steam header to the deaerator.

6. A method for using the system for increasing boiler feed water temperature during pipe blowing according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step a, assembling a system for increasing boiler feed water temperature during blowpipe; Step b, during normal operation of the unit, the cold recirculation to auxiliary steam header channel and the cold recirculation to heater channel are both connected to the cold recirculation pipeline, and high-temperature steam is supplied to the high-pressure heater group and the auxiliary steam header respectively; During step c, pipe blowing, the auxiliary steam header is connected to the deaerator and the second high-pressure heater respectively, and the drain pipeline is connected. The high-temperature steam entering the deaerator is directly mixed with the feed water to heat it. After the feed water in the deaerator is pressurized by the feed water pump, it passes through the third high-pressure heater, the second high-pressure heater and the first high-pressure heater in sequence. The high-temperature steam entering the second high-pressure heater heats the feed water from the deaerator again, and the feed water enters the boiler after being heated; the drain from the second high-pressure heater returns to the deaerator through the drain pipeline.

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