Heat exchange device capable of effectively preventing ash blocking

Abstract

The application discloses a heat exchange device capable of effectively preventing dust blocking, relates to a flue dust removal device, and solves the technical problem of poor dust removal effect of a steam dust removal method in a current air preheater heat exchange device. The heat exchange device comprises an air preheater, a first sound wave soot blower installed in a flue gas bin, a second sound wave soot blower installed in an air side flue, and a third sound wave soot blower integrated with the second sound wave soot blower. The third sound wave soot blower is used for generating sound pulses capable of driving dust particles in flue gas to vibrate synchronously, so as to prevent the dust particles in the flue gas from depositing on air section heat exchange elements in the air side flue. The application has a reasonable structure, is practical and reliable, and achieves better dust removal and energy saving effects.

Description

TECHNICAL FIELD

[0001] The present application relates to a flue dusting equipment, more particularly, to a heat exchange device capable of effectively preventing dust blocking. BACKGROUND

[0002] In order to reduce the waste of heat energy, the air preheater is generally configured in the flue of the boiler in the unit of the power plant to realize the recycling of the heat energy in the high-temperature flue gas discharged by the boiler. Figure 1 As shown in the figure, the current air preheater 1 is mostly a three-bay regenerative air preheater. The flue gas generated in the boiler furnace flows through the back flue, enters the flue gas bay 2 of the air preheater 1 through the flue gas passage. In addition, the air preheater 1 is separated into the primary air passage 4 and the secondary air passage 5 by the sealing sheet 3, which are collectively referred to as the air side flue 8 in this paper. The angle of the primary air can be arbitrarily changed under the premise that the flue gas passage is unchanged to adapt to the needs of different fuels. The current standardized angles are 35° and 50°.

[0003] The heat exchange elements 7 (including the air section heat exchange elements 72 and the flue gas section heat exchange elements 71) installed on the rotor 6 of the air preheater 1 absorb heat from the flue gas in the flue gas bay 2 and then transfer the heat to the air when passing through the air side flue 8. The air section heat exchange elements 72 and the flue gas section heat exchange elements 71 both include cold sections and hot sections. The hot section is the section of the heat exchange elements 7 close to the heat source, and the cold section is the section of the heat exchange elements 7 away from the heat source. For example, in the flue gas section heat exchange elements 71, the windward side of the high-temperature flue gas is the hot section, and the leeward side is the cold section; in the air section heat exchange elements 72, the windward side of the cold air is the cold section, and the leeward side is the hot section. A gap is provided between the cold section and the hot section to separate the cold section and the hot section. Due to the slow rotation of the rotor 6, the heat exchange elements 7 alternately pass through the flue gas bay and the air side passage. The heat exchange elements 7 absorb heat and accumulate it when in contact with the flue gas, and release the stored heat to heat the air when in contact with the air, and so on. The flue gas out of the air preheater 1 is discharged to the chimney through the electrostatic precipitator, the desulfurization island and the induced draft fan. The electric closing baffle is installed on the inlet and outlet flues of the air preheater 1.

[0004] Among them, the primary air is used for conveying and drying the pulverized coal. The primary air fan sucks air from the atmosphere and sends it into the primary air separation bay of the three-bay regenerative air preheater, and after being heated, it enters the primary air main through the primary air passage. Before entering the air preheater, a part of the cold air is bypassed through the cold primary air passage, and is mixed with the hot primary air in the primary air main to adjust the temperature of the primary air.

[0005] The secondary air is used to strengthen combustion and control the amount of NOx generated. The air sucked from the atmosphere enters the secondary air separation bay of the air preheater through the air fan, and after being heated, it enters the large air tank as auxiliary air through the secondary air passage, and enters the coal mill of the coal pulverizing system as drying air.

[0006] During the combustion process of the boiler, some ash will be entrained in the high-temperature flue gas generated by the boiler, which will be accumulated on the heat exchange elements and will be detrimental to heat exchange and flue gas passing through the air heat exchanger. In order to remove the accumulated ash and blockage in the air preheater, a steam sootblower (such as a steam sootblower of model PS-AT) is designed to remove the ash particles on the heat exchange elements. Specifically, one steam sootblower and a high-pressure water flushing sootblower are installed in the cold section and the hot section of the flue gas bin, respectively. The jet impact force of the high-pressure steam of the boiler rear screen superheater is used to remove the accumulated ash on the surface of the air preheater heat exchange elements, so that the accumulated ash is removed. The design sootblowing frequency is once a day.

[0007] After the denitration modification, since the boiler denitration adopts the SCR liquid ammonia reaction reduction catalytic technology, the original air preheater inlet flue gas temperature is reduced by 20-30℃, and the sulfuric acid hydrogen ammonia product generated by flue gas denitration is increased. Due to the high sulfur content and high moisture content in the coal used, more ash will be generated during the operation of the boiler. These ashes will enter the air preheater along with the flue gas, causing the heat exchange elements of the air preheater to be more prone to ash accumulation and blockage. This will affect the effective operation of the unit.

[0008] For example, the air preheater after denitration modification has appeared several times with an inlet and outlet flue gas differential pressure resistance of 2000Pa to 5000Pa, which is far more than the design value of 1100Pa. The pressure difference changes periodically. This will cause the induced draft fan output to be uneven, with wind volume being large and small, causing the furnace negative pressure to fluctuate greatly, affecting the stable combustion of the boiler, and in severe cases, causing the induced draft fan and the forced draft fan to surge at the same time. This will eventually cause the unit load to decrease, such as from 300MW full load to 200MW, so that the unit cannot be loaded to full capacity.

[0009] In order to solve the problem that the unit cannot be loaded to full capacity, the current method is to increase the sootblowing frequency of the steam sootblower used for sootblowing the heat exchange elements in the air heat exchanger from one shift per day to twice a day; or even the steam sootblower is forced to be used for 24 hours. However, this will cause the heat exchange elements to be severely scaled and corroded, causing the surface of the heat exchange elements to easily fall off, affecting the heat exchange performance of the heat exchange elements, and seriously affecting the safe operation of the unit.

[0010] After several times of maintenance and fault checking, it is found that the reason that the unit cannot run at full load is that the steam blowing ash method relies on the impact force of steam to realize ash cleaning. However, the amount of ash particles and the temperature of flue gas will affect the impact force of steam flow. Due to the increase of ash particles and the decrease of flue gas temperature, the impact force of steam at the end of the steam flow is greatly attenuated compared with before the transformation. In addition, due to the defects of the steam ash blower itself, if the steam is not drained well or not enough before blowing, the steam blows on the heat exchange element after carrying water, which makes the ash particles more easily adhere and deposit on the heat exchange element, and the blowing effect is very poor and the local ash deposition is serious. In addition, due to the increase of ash particles, the spray nozzle of the steam ash blower is more prone to blockage, thereby affecting the normal blowing of the equipment. SUMMARY

[0011] The technical problem to be solved by the present application is to provide an effective anti-ash heat exchange device to solve the problem of poor ash cleaning effect in the current air preheater heat exchange device using steam ash cleaning method.

[0012] The effective anti-ash heat exchange device provided by the present application comprises an air preheater, and further comprises,

[0013] A first sound wave ash blower installed in the flue gas chamber is used to cut compressed air at a fixed frequency to generate sound pulses to blow ash on the flue gas section heat exchange element located in the flue gas chamber;

[0014] A second sound wave ash blower installed in the air side flue is used to cut compressed air at a fixed frequency to generate sound pulses to blow ash on the air section heat exchange element located in the air side flue;

[0015] A third sound wave ash blower integrated with the second sound wave ash blower is used to generate sound pulses that can move the ash particles in the flue gas to vibrate synchronously to prevent the ash particles in the flue gas from depositing on the air section heat exchange element in the air side flue, achieving better ash cleaning effect.

[0016] The second sound wave ash blower and the third sound wave ash blower are both installed on the outside of the air side flue, and the sound emitting speakers of the second sound wave ash blower and the third sound wave ash blower both penetrate and extend into the air side flue; a sound wave transfer cover one is fixedly installed on the side of the air section heat exchange element in the air side flue in the wind direction, and the sound emitting speakers of the second sound wave ash blower and the third sound wave ash blower are both fixedly installed on one side of the sound wave transfer cover one, and the sound emitting speakers of the second sound wave ash blower and the third sound wave ash blower are in communication with the sound wave transfer cover one.

[0017] The output end of the sound wave transfer cover one is opposite to the air section heat exchange element, and the minimum distance between the sound wave transfer cover one and the air section heat exchange element is 400mm-600mm.

[0018] The second acoustic soot blower adopts a flying disc type acoustic soot blower.

[0019] The third acoustic soot blower adopts a frequency-modulated electric acoustic soot blower.

[0020] The first acoustic soot blower is fixedly installed on the outer side of the flue gas chamber, and the sound emitting horn of the first acoustic soot blower penetrates and extends into the flue gas chamber; the sound wave transfer cover two is fixedly installed on the side of the flue gas chamber located in the windward direction of the flue gas section heat exchange element, and the sound emitting horn of the first acoustic soot blower is fixedly installed on one end of the sound wave transfer cover two, and the sound emitting horn of the first acoustic soot blower is in communication with the sound wave transfer cover two.

[0021] The output end of the sound wave transfer cover two is opposite to the flue gas section heat exchange element, and the minimum distance between the sound wave transfer cover two and the flue gas section heat exchange element is 400mm-600mm.

[0022] The first acoustic soot blower adopts a flying disc type acoustic soot blower.

[0023] The first acoustic soot blower, the second acoustic soot blower and the third acoustic soot blower work for a set working time length with a set cycle period.

[0024] The cycle period is 24 hours, and the working time length is 60 seconds-300 seconds.

[0025] Beneficial effects

[0026] The advantages of the present application are:

[0027] 1. The acoustic soot blower is arranged on the flue gas chamber and the air side of the flue gas pipeline, the deposited ash particles on the heat exchange element are stripped by the sound pulse, so that the purpose of ash removal is achieved. The attenuation of the sound pulse is smaller than that of the steam flow, which is beneficial to transmission in the heat exchange element; the sound pulse ash removal does not appear the phenomenon of water carrying, which avoids the problem that the steam carrying water causes the heat exchange element to be damp, resulting in more serious ash deposition; the sound wave soot blower also does not appear the problem that the sound wave output end is blocked, and the ash removal is effective and reliable.

[0028] 2. The frequency-modulated electric acoustic soot blower is arranged on one side of the air section heat exchange element to generate sound pulses that can drive the ash particles in the flue gas to vibrate synchronously, so that the newly adsorbed ash particles are prevented from depositing and condensing, and a better ash removal effect is achieved.

[0029] 3. The three acoustic soot blowers work for a set working time length with a set cycle period, which can comprehensively remove the ash on the cold section and the hot section of the heat exchange element, and also achieves a better ash removal and energy saving effect. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a schematic diagram of the local structure of the traditional air preheater.

[0031] Figure 2 The heat exchange device structure diagram of the present application.

[0032] 1-air preheater, 2-flue gas bin, 3-sealing sheet, 4-primary air channel, 5-secondary air channel, 6-rotor, 7-heat exchange element, 71-flue gas section heat exchange element, 72-air section heat exchange element, 8-air side flue, 9-first acoustic blower, 10-second acoustic blower, 11-third acoustic blower, 12-acoustic transfer cover one, 13-acoustic transfer cover two, 14-gas storage tank, 15-solenoid valve, 16-ball valve. DETAILED DESCRIPTION

[0033] The present application will be further described below in conjunction with the embodiments, but does not constitute any limitation to the present application, and any limited number of modifications made by anyone within the scope of the claims of the present application is still within the scope of the claims of the present application.

[0034] Reference Figure 2 The present application is a heat exchange device effectively preventing ash blocking, comprising an air preheater 1, a first acoustic blower 9, a second acoustic blower 10 and a third acoustic blower 11.

[0035] The first acoustic blower 9 is used to cut compressed air at a fixed frequency to generate acoustic pulses, and to perform ash removal treatment on the flue gas section heat exchange element 71 located in the flue gas bin 2. More specifically, the output end of the first acoustic blower 9 is directly opposite the hot section of the flue gas section heat exchange element 71, mainly to blow off the ash particles deposited in the hot section of the flue gas section heat exchange element 71.

[0036] The first acoustic blower 9 is fixedly installed on the outside of the flue gas bin 2, and the sound emitting horn of the first acoustic blower 9 penetrates and extends into the flue gas bin 2. The acoustic transfer cover two 13 is fixedly installed on the side of the flue gas bin 2 located in the windward direction of the flue gas section heat exchange element 71, the sound emitting horn of the first acoustic blower 9 is fixedly installed on one end of the acoustic transfer cover two 13, and the sound emitting horn of the first acoustic blower 9 is in communication with the acoustic transfer cover two 13. The acoustic transfer cover two 13 is a cover body with gradually increasing diameter, which is mainly provided to make the acoustic pulses emitted by the first acoustic blower 9 act on the length part of the flue gas section heat exchange element 71, and reduce the dead zone position.

[0037] In addition, the output end of the acoustic transfer cover two 13 is directly opposite the flue gas section heat exchange element 71, so that the acoustic pulses directly impact on the flue gas section heat exchange element 71, which is beneficial to the ash removal operation.

[0038] The minimum distance between the sound wave transfer cover 2 13 and the flue gas section heat exchange element 71 is 400mm-600mm. The preferred distance is 500mm, which avoids the problem of too large distance between the sound wave transfer cover 2 13 and the flue gas section heat exchange element 71 leading to too weak sound pulse, and also avoids the problem of too small distance between the sound wave transfer cover 2 13 and the flue gas section heat exchange element 71 leading to too much sound pulse being reflected back when the sound pulse contacts the flue gas section heat exchange element 71.

[0039] To realize the cutting of compressed air by the first sound wave soot blower 9 at a fixed frequency, the first sound wave soot blower 9 of the embodiment adopts a flying disc type sound wave soot blower. However, it is not limited to the flying disc type sound wave soot blower, but also can adopt a diaphragm type sound wave soot blower or an acetylene shock wave soot blower.

[0040] The flying disc type sound wave soot blower is driven by an electric motor to modulate the cutting air flow. For example, the FLAMING-95FD sound wave soot blower has four cutting knives on the moving cutting piece to cut the compressed air flowing into the static nozzle at a speed of 95 times per second to generate the sound frequency. The cooperation between the moving cutting piece and the static nozzle is precise, only 0.03mm. The compressed air is cut by high speed mechanical movement to generate 95Hz strong sound pulse, the output frequency is stable, pure and the sound intensity is as high as 156db. When the sound pulse propagates in the flue, the ash deposited on the heat exchange element 7 is destroyed and peeled off under the repeated action of sound wave vibration and fatigue movement, so that the purpose of soot removal is achieved.

[0041] The second sound wave soot blower 10 and the third sound wave soot blower 11 of the embodiment are installed outside the air side flue 8, and the sound emitting horn of the second sound wave soot blower 10 and the third sound wave soot blower 11 penetrates and extends into the air side flue 8. The sound wave transfer cover 1 12 is fixedly installed on the side of the air side flue 8 located in the windward direction of the air section heat exchange element 72, and the sound emitting horn of the second sound wave soot blower 10 and the third sound wave soot blower 11 are fixedly installed on one side of the sound wave transfer cover 1 12, and the sound emitting horn of the second sound wave soot blower 10 and the third sound wave soot blower 11 communicates with the sound wave transfer cover 1 12. The sound wave transfer cover 1 12 is a cover body with gradually increasing diameter, which is mainly arranged to make the sound pulse emitted by the second sound wave soot blower 10 and the third sound wave soot blower 11 act on the length part of the air section heat exchange element 72, and reduce the dead zone position.

[0042] The second sound wave soot blower 10 is used to cut the compressed air to generate sound pulse at a fixed frequency, and to perform soot blowing treatment on the air section heat exchange element 72 located in the air side flue 8. More specifically, the output end of the second sound wave soot blower 10 is opposite to the cold section of the air section heat exchange element 72, and mainly plays a role in blowing off the ash deposited in the cold section of the air section heat exchange element 72.

[0043] The heat exchange device is in the working project, the flue gas section heat exchange element 71 of the heat exchange element 7 therein is the main dust deposition site. And the hot section and the cold section of the flue gas section heat exchange element 71 can all produce the problem of dust deposition. The output end of the first acoustic soot blower 9 is opposite to the hot section of the flue gas section heat exchange element 71, which can realize soot blowing treatment for the hot section of the flue gas section heat exchange element 71. But the cold section of the flue gas section heat exchange element 71 is in the leeward side, if the soot blowing device is installed below the cold section of the flue gas section heat exchange element 71, it is not conducive to the work of the soot blowing device, and it is easy to cause the problem of soot blowing blockage.

[0044] Therefore, according to the rotatable characteristics of the heat exchange element 7, the device for removing dust from the cold section, i.e. the second acoustic soot blower 10, is arranged in the air side flue 8, and the sound wave output direction of the second acoustic soot blower 10 is in the same direction as the flow direction of the air, thereby avoiding the problem that the output end of the soot blowing device faces the flow direction of the air flow, which causes the soot blowing device to be prone to blockage.

[0045] In order to realize the cutting of compressed air by the second acoustic soot blower 10 at a fixed frequency, the second acoustic soot blower 10 of the embodiment adopts a flying disc type acoustic soot blower. But it is not limited to the flying disc type acoustic soot blower, and a diaphragm type acoustic soot blower or an acetylene shock wave soot blower can also be used.

[0046] The third acoustic soot blower 11 is used to generate a sound pulse that can drive the synchronous vibration of the ash particles in the flue gas, so as to prevent the ash particles in the flue gas from depositing on the air section heat exchange element 72 in the air side flue 8. In order to realize the sound pulse that can drive the synchronous vibration of the ash particles in the flue gas, the frequency of the sound pulse of the third acoustic soot blower 11 should be adjustable, so that the frequency of the sound pulse generated thereby can be adjusted to the resonance frequency of the ash particles. Therefore, the third acoustic soot blower 11 is preferably a frequency-modulated electric acoustic soot blower, such as a FLAMING-90 soot blower.

[0047] Because the air section heat exchange element 72 has a low temperature and is prone to low-temperature corrosion and fouling, and when the flue gas section heat exchange element 71 is turned into the air side flue 8, the newly adsorbed ash particles on the heat exchange element 7 will be more likely to deposit and condense on the heat exchange element 7 after cooling. Based on this, two acoustic soot blowers are arranged on one side of the air section heat exchange element 72 in the embodiment, so as to simultaneously perform acoustic pulse dust removal on the original ash particles on the air section heat exchange element 72, and simultaneously prevent the newly adsorbed ash particles from depositing and condensing through the sound pulse that can drive the synchronous vibration of the ash particles in the flue gas, thereby achieving a better dust removal effect.

[0048] The output end of the acoustic wave transfer cover 12 is opposite to the air section heat exchange element 72, so that the sound pulse directly impacts on the air section heat exchange element 72, which is conducive to the dust removal operation.

[0049] The minimum distance between the sound wave transferring cover 12 and the air section heat exchanging element 72 is 400mm-600mm. Preferably, it is 500mm, which can avoid the problem of too weak sound pulse caused by too large distance between the sound wave transferring cover 12 and the air section heat exchanging element 72, and can also avoid the problem of too much sound pulse being reflected back when the sound pulse contacts the air section heat exchanging element 72 caused by too small distance between the sound wave transferring cover 12 and the air section heat exchanging element 72.

[0050] The first sound wave soot blower 9, the second sound wave soot blower 10 and the third sound wave soot blower 11 work for a set working time length in a set cycle period. The cycle period is 24 hours, i.e. the sound wave soot blower is started once a day to clean the heat exchanging element 7.

[0051] The working time length of cleaning is 60 seconds-300 seconds. Preferably, it is 60 seconds. The rotation frequency of the rotor 6 in the air preheater 1 is 60 seconds per rotation, i.e. the working frequency of the sound wave soot blower is set to be consistent with the automatic rotation period of the rotor 6 in the air preheater 1 per minute, so that the three sound wave soot blowers can clean the cold section and the hot section on the heat exchanging element 7 comprehensively, and the better cleaning and energy saving effect is achieved.

[0052] The sound wave soot blower also needs to be connected with compressed gas to realize the sound generating function during use. Therefore, the compressed air input ends of the three sound wave soot blowers in the embodiment are connected with the compressed air storage tank 14 through pipelines. The solenoid valve 15 is installed on the pipeline to realize the automatic control of the pipeline opening and closing through the controller. In addition, the ball valve 16 is also installed on the pipeline to facilitate the manual operation of the pipeline opening and closing on site.

[0053] The above only describes the preferred embodiment of the present application, and it should be noted that the person skilled in the art can make several modifications and improvements without departing from the structure of the present application, which will not affect the effect and practicality of the present application.

Claims

1. A heat exchange device effective to prevent dust clogging, comprising an air preheater (1), characterized in that, Also include, The first sound wave soot blower (9) is installed in the flue gas warehouse (2), is used for cutting compressed air to produce sound pulse at fixed frequency, and is used for soot blowing treatment to the flue gas section heat exchange element (71) in the flue gas warehouse (2); The second sound wave soot blower (10) is installed in the air side flue (8), is used for cutting compressed air to produce sound pulse at fixed frequency, and is used for soot blowing treatment to the air section heat exchange element (72) in the air side flue (8); The third sound wave soot blower (11) is installed with the second sound wave soot blower (10) integration, is used for producing the sound pulse that can drag the synchronous vibration of ash particle in flue gas, to prevent ash particle in flue gas from depositing on the air section heat exchange element (72) in the air side flue (8); The second sound wave soot blower (10) adopts flying disc type sound wave soot blower; The third sound wave soot blower (11) adopts frequency modulation type electric sound wave soot blower; The first sound wave soot blower (9) adopts flying disc type sound wave soot blower.

2. The heat exchange device according to claim 1, wherein The second sound wave soot blower (10) and third sound wave soot blower (11) are all installed in the outside of the air side flue (8), and the sound emitting horn of the second sound wave soot blower (10) and third sound wave soot blower (11) all penetrates and extends to the air side flue (8);The air side flue (8) is fixedly installed with sound wave transfer cover one (12) on the side of air section heat exchange element (72) in the windward direction, and the sound emitting horn of the second sound wave soot blower (10) and third sound wave soot blower (11) are all fixedly installed on one side of sound wave transfer cover one (12), and the sound emitting horn of the second sound wave soot blower (10) and third sound wave soot blower (11) are communicated with sound wave transfer cover one (12).

3. The heat exchange device according to claim 2, wherein The output end of the sound wave transfer cover one (12) is opposite to the air section heat exchange element (72), and the minimum spacing between the sound wave transfer cover one (12) and the air section heat exchange element (72) is 400mm-600mm.

4. The heat exchange device according to claim 1, wherein The first sound wave soot blower (9) is fixedly installed on the outside of the flue gas warehouse (2), and the sound emitting horn of the first sound wave soot blower (9) penetrates and extends to the flue gas warehouse (2);The flue gas warehouse (2) is fixedly installed with sound wave transfer cover two (13) on the side of flue gas section heat exchange element (71) in the windward direction, and the sound emitting horn of the first sound wave soot blower (9) is fixedly installed on one end of sound wave transfer cover two (13), and the sound emitting horn of the first sound wave soot blower (9) is communicated with sound wave transfer cover two (13).

5. The heat exchange device according to claim 4, wherein The output end of the sound wave transfer cover two (13) is opposite to the flue gas section heat exchange element (71), and the minimum spacing between the sound wave transfer cover two (13) and the flue gas section heat exchange element (71) is 400mm-600mm.

6. The heat exchange device according to claim 1, wherein The first sound wave soot blower (9), the second sound wave soot blower (10) and the third sound wave soot blower (11) work for a set working time length with a set cycle period.

7. The heat exchange device according to claim 6, wherein The cycle period is 24 hours;The working time length is 60 seconds-300 seconds.

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