CN110332559B

CN110332559B - Smoke heat exchanger

Info

Publication number: CN110332559B
Application number: CN201910672213.1A
Authority: CN
Inventors: 李振建; 赵昕盟
Original assignee: Shandong Wintech Technology Co ltd
Current assignee: Shandong Wintech Technology Co ltd
Priority date: 2019-07-24
Filing date: 2019-07-24
Publication date: 2021-11-12
Anticipated expiration: 2039-07-24
Also published as: CN110332559A

Abstract

The invention relates to a flue gas heat exchanger, which belongs to the technical field of heat exchangers; the device comprises a plurality of flue gas heat exchanger units which are connected in parallel, wherein each flue gas heat exchanger unit comprises a shell, a steam inlet, a steam outlet and a heat exchange core body; the heat exchange core body comprises a plurality of plate pairs which are stacked layer by layer, each plate pair comprises an upper plate and a lower plate which are arranged oppositely, each plate pair forms a cold flue gas flow channel, two adjacent plate pairs form a hot steam flow channel, convex bulges and concave bulges which are arranged in a staggered mode are arranged on the plates, the convex bulges protrude towards one side of the cold flue gas flow channel, and the concave bulges protrude towards the other side; an omega-shaped supporting strip is arranged in the cold flue gas flow channel, is fixed on the convex drum, is in an omega-shaped hollow strip shape, and is arranged in the same direction as the flue gas flowing direction in the hot flue gas flow channel; high heat exchange efficiency, high pressure resistance, small occupied space and small change of flue gas flow velocity.

Description

Smoke heat exchanger

Technical Field

The invention relates to a flue gas heat exchanger, and belongs to the technical field of heat exchangers.

Background

The desulfurized clean flue gas is discharged into the atmosphere from a chimney without being heated, namely the wet flue gas is discharged. The exhausted wet flue gas is contacted and mixed with ambient air with a relatively low temperature, during which the temperature and the moisture content are continuously reduced. During the mixing process of the smoke and the air, the water vapor contained in the smoke is supersaturated and condensed, and condensed water drops refract and scatter light, so that the smoke plume is white or gray, and is called as 'wet smoke plume' (namely 'big white smoke', 'white fog', 'white smoke plume', 'colored smoke plume', and the like). When wet flue gas is discharged, the lifting height of the smoke plume is reduced, the diffusion effect is relatively poor, the landing concentration of pollutants at the accessory of the chimney is increased, and the surrounding environment is influenced to a certain extent. At present, the basic principle of the 'wet smoke plume' treatment technology is to change the temperature or humidity of smoke gas to avoid the 'wet smoke plume' phenomenon caused by supersaturation and condensation due to the reduction of the temperature of the smoke gas in the process of mixing the smoke gas and ambient air, and a smoke gas reheating method is the most common technical idea and improves the temperature of the smoke gas through measures of gas-gas heat exchange, gas-water-gas heat exchange, blending high-temperature gas and the like. Such as rotary GGH, tubular GGH, heat pipe GGH, MGGH, steam heat exchange, hot secondary air, etc. MGGH is the technology in which applications perform the most.

The MGGH technology utilizes water as a medium, absorbs the heat of flue gas in front of a desulfurizing tower, heats the flue gas at the inlet of a chimney, can effectively improve the temperature of the flue gas, improves the diffusion capacity of the flue gas, and eliminates liquid drops. Wherein, the desulfurized flue gas heater is in low-temperature wet saturated flue gas for a long time and is subject to serious corrosion of H2SO3, H2SO4, HCl and HNO3, and the existing flue gas temperature raising section mostly adopts a fluoroplastic heat exchanger and a metal tube flue gas heater. The fluoroplastic heat exchanger is in a light tube form, has very smooth surface and moderate flexibility, can avoid scaling, but has low pressure resistance and is not enough to bear steam with higher pressure. The metal tube smoke heater faces the problems of dust deposition and scaling, and scaling among fins is not easy to remove. Meanwhile, the resistance of the fluoroplastic heat exchanger and the metal pipe flue gas heater is reduced, and the corresponding original booster fan needs to be replaced due to the fact that the pressure is increased and the overload work is carried out, so that the investment cost is increased invisibly; the occupied area is large, and enough space must be provided for installing the heat exchanger at the process point of improving the temperature rise of the flue gas.

Disclosure of Invention

In order to solve the technical problems, the invention provides the flue gas heat exchanger which is high in heat exchange efficiency, high in pressure resistance, small in occupied space and small in flue gas flow velocity change.

The flue gas heat exchanger comprises a plurality of flue gas heat exchanger units which are connected in parallel, each flue gas heat exchanger unit comprises a shell, a steam inlet, a steam outlet and a heat exchange core, the steam inlets and the steam outlets are arranged on two sides of a hot steam flow channel, and the heat exchange cores, the steam inlets and the steam outlets are fixed on the shells; the heat exchange core body comprises a plurality of plate pairs which are stacked layer by layer, each plate pair comprises an upper plate and a lower plate which are arranged oppositely, each plate pair forms a cold flue gas flow channel, two adjacent plate pairs form a hot steam flow channel, convex bulges and concave bulges which are arranged in a staggered mode are arranged on the plates, the convex bulges protrude towards one side of the cold flue gas flow channel, and the concave bulges protrude towards the other side; the cold flue gas flow channel is internally provided with an omega-shaped supporting strip which is fixed on the convex drum, the omega-shaped supporting strip is in an omega-shaped hollow strip shape, and the setting direction of the omega-shaped supporting strip is the same as the circulation direction of the flue gas in the cold flue gas flow channel.

The bulge structure can effectively enhance the fluid disturbance, greatly enhance the heat transfer effect and has high heat exchange efficiency; but also can enhance the strength of the plate under the premise of smaller resistance drop and has high pressure resistance. The design of the omega-shaped supporting strips plays a supporting role and forms a wide-gap flue gas flow channel; the supporting function of the omega supporting bars further improves the pressure resistance; because the steam flow channel clearance is extremely small relative to the wide clearance cold flue gas flow channel clearance, the influence on the flue gas flow velocity is small, the size of the flue is almost unchanged, the size does not need to be increased, the flue gas heat exchanger stretches across the flue port, the occupied space is small, and the flue gas flow velocity change is small.

Preferably, the convex bulge is an elliptical platform, and the concave bulge is a circular platform; further reduce the resistance and fall, increase the strength of the plate and better support the flue gas flow passage and the steam flow passage.

Preferably, the height of the concave bulge is 2.5-3mm, and the height of the omega-shaped support strip is calculated according to the flow rate of flue gas and pressure drop, and is preferably 10-40 mm; the hot steam flow passage gap is further highlighted to be extremely small relative to the wide gap cold flue gas flow passage gap, the influence on the flow speed of the flue gas is small, the size of the flue gas is almost unchanged, the size does not need to be increased, the flue gas heat exchanger stretches across the flue port, the occupied space is small, and the change of the flow speed of the flue gas is small.

Preferably, the distance between the convex bulges is 75-85mm, and the distance between the concave bulges is 35-45 mm; further, the strength of the plate is enhanced on the premise of smaller resistance drop, and the pressure resistance is high.

Preferably, the steam inlet and the steam outlet are hollow semi-cylindrical round plate shells or hollow rectangular parallelepiped tube boxes; can bear larger pressure of hot steam, and further improves the pressure resistance.

Preferably, the flue gas heat exchanger unit further comprises a filtering device, wherein the filtering device comprises a plurality of rows of tube bundles which are fixed on the air inlet side of the cold and hot flue gas flow passage; the easy-scaling substances carried by the flue gas are mostly condensed on the filtering device, and the scale of the plate sheets is light.

Preferably, the flue gas heat exchanger unit further comprises an overhaul channel, the overhaul channel is arranged between the heat exchange core and the filtering device and is communicated with the shell and the filtering device; on one hand, the device is beneficial to observing the scaling condition, on the other hand, the device is beneficial to removing scaling substances and is convenient to maintain.

Preferably, the shell comprises a frame and two box plates, the box plates are welded on the frame, and the frame is welded with the heat exchange core body; the frame comprises two 'dish' -shaped frames and four 'I' -shaped frames, every two of the four 'I' -shaped frames are welded at two ends of the two 'dish' -shaped frames in a group, and the box plate is respectively welded on the two 'dish' -shaped frames; the frame plays the effect of supporting the heat transfer core, and the boxboard is used as the clamp plate and bears steam side pressure, further improves the pressure resistance.

Preferably, the highest positions of the steam inlet and the steam outlet are provided with exhaust holes, and the lowest positions of the steam inlet and the steam outlet are provided with liquid discharge holes; so that the impurity gas can be discharged in time, and the condensed liquid in the steam can be discharged.

Preferably, the thickness of the omega-shaped supporting strip is 1-2mm, the circulation space of the cold flue gas flow channel is further enlarged on the premise of ensuring the supporting, the occupied space is small, and the flow rate change of the flue gas is small.

Compared with the prior art, the invention has the following beneficial effects:

the heat exchange efficiency is high, the pressure resistance is high, the occupied space is small, the change of the flow velocity of the flue gas is small, the scaling of the plate sheets is light, the scaling condition can be observed conveniently, scaling substances can be removed, and the maintenance is convenient.

Drawings

FIG. 1 is a schematic structural view of a heat exchange core according to the present invention;

FIG. 2 is an exploded view of the flue gas heat exchanger unit structure of the present invention;

FIG. 3 is an elevation view of the cold flue gas flow path of the present invention;

FIG. 4 is a view of the structure of the omega brace bar of the present invention;

FIG. 5 is a front view of a hot steam flowpath according to the present invention;

fig. 6 is a schematic structural diagram of the cold flue gas heat exchanger of the present invention.

Wherein: 1. a housing; 101. a boxboard; 102. a "dish" shaped frame; 103. a "one" shaped frame; 2. a steam inlet; 201. an exhaust hole; 202. a drain hole; 3. a steam outlet; 4. a heat exchange core body; 401. a hot steam runner; 402. a cold flue gas flow passage; 403. omega supporting bars; 404. a sheet; 405. bulging; 406. concave bulging; 407. a hollow space; 408. a top end; 409. a bottom end; 5. overhauling the channel; 6. a filtration device; 601. a tube bundle; 602. a tube sheet; 603. a connecting pipe; 7. a flue gas heat exchanger unit.

Detailed Description

Example 1

As shown in fig. 1, the heat exchange core 4 includes a plurality of plate pairs stacked layer by layer, each plate pair includes an upper plate 404 and a lower plate 404 arranged in opposite directions, each plate pair forms a cold flue gas flow channel 402, two adjacent plate pairs form a hot steam flow channel 401, the plate 404 is provided with convex bulges 405 and concave bulges 406 arranged in a staggered manner, the convex bulges 405 protrude towards one side of the cold flue gas flow channel 402, the concave bulges 406 protrude towards the other side, and the number of the plate pairs may be 5; an omega-shaped supporting strip 403 is arranged in the cold flue gas flow channel 402, the omega-shaped supporting strip 403 is fixed on the convex bulge 405, and the arrangement direction of the omega-shaped supporting strip is the same as the circulation direction of flue gas in the cold flue gas flow channel 402. The convex bulges 405 and the concave bulges 406 are formed by die pressing in rows at certain intervals and are used for enhancing the strength of the plate. The distance between the convex bulges 405 is preferably 75-85mm, and the distance between the concave bulges 406 is preferably 35-45mm, so that the strength of the plate can be enhanced, and the resistance drop is small. The convex bulge 405 may be an elliptical frustum and the concave bulge 406 may be a circular frustum. The convex bulge 405 is arranged inclined at an angle, preferably between 55 and 65 degrees, which serves to reduce the influence on the flue gas flow rate. The plate 404 is made of high-quality corrosion-resistant stainless steel, the bulge structure can effectively enhance fluid disturbance and greatly enhance the heat transfer effect, and the height of the plate is higher than that of a polytetrafluoroethylene heat exchanger and a tubular heat exchanger.

As shown in fig. 2, the flue gas heat exchanger unit includes a shell 1, a steam inlet 2, a steam outlet 3, and a heat exchange core 4, wherein the steam inlet 2 and the steam outlet 3 are disposed at two sides of a hot steam flow channel 401, and the heat exchange core 4, the steam inlet 2, and the steam outlet 3 are fixed on the shell 1. The shell 1 comprises a frame and a box plate 101, the frame is formed by welding profile steels, the box plate 101 is welded on the frame, the frame is welded with the heat exchange core body 4, the frame plays a role in supporting the heat exchange core body 4, and the box plate 101 serves as a pressure plate for bearing the steam side pressure. The frame comprises two dish-shaped frames 102 and four I-shaped frames 103, and the four I-shaped frames 103 are welded at two ends of the two dish-shaped frames 102 in groups of two. The number of the box plates 101 is 2, and the box plates are welded between two dish-shaped frames 102. The steam inlet 2 is welded on one group of the 'one' shaped frames 103, and the steam outlet 3 is welded on the other group of the 'one' shaped frames 103. The frame is welded with the other two sides of the non-hot steam flow channel 401 and the non-cold flue gas flow channel 402 of the heat exchange core 4. The thickness of the shell 1 is calculated according to the pressure bearing capacity, and the higher the pressure bearing capacity is, the thicker the thickness is. Specifically, the frame selects section steel with a proper specification by calculating self load and additional load, and preferably selects H-shaped steel; the thickness of the box plate 101 is calculated based on the pressure of the hot steam flow path 401, and the thickness is increased as the pressure is increased. The shell 1 is coated with anticorrosive paint or a stainless steel coating according to the conditions of smoke components, temperature, humidity and the like.

As shown in fig. 3 and 4, the Ω -shaped support bars 403 are in the shape of Ω -shaped hollow strips, are arranged on a sheet of plate at certain intervals according to the arrangement of the convex bumps 405 and the pressure-bearing capacity, are fixed on the convex bumps 405 by spot welding, have the same length as the cold flue gas flow channel 402, play a role of supporting, form a wide-gap cold flue gas flow channel 402, have a larger interval, and can bear larger pressure. The stronger the bearing capacity, the greater the number of the Ω support bars 403. The height of the omega-shaped supporting strip 403 is calculated according to the flow velocity and pressure drop of the flue gas, and the thickness is preferably 1-2 mm. Through the wide clearance design of cold flue gas runner 402, reduce the flue gas circulation resistance and fall to reduce former booster fan work load, the energy saving, reduce cost. The setting direction of the omega-shaped supporting strip 403 is the same as the smoke flowing direction in the cold smoke channel 402, the hollow space 407 is used as a part of the cold smoke channel 402, cold smoke can pass through, the structure is compact, the flowing space of the cold smoke channel 402 is basically not influenced, the change of the smoke flow speed is small, and the smoke flowing resistance is reduced. The distance between the cold flue gas flow channels 402 is calculated according to the fact that the distance between the cold flue gas flow channels 402 is larger, the flow rate is smaller, and the pressure drop is smaller, and the purpose of adjusting the distance between the cold flue gas flow channels 402 is achieved by adjusting the height of the omega-shaped supporting strips 403. As shown in fig. 3, to further increase the support strength, the top 408 and bottom 409 ends of the omega-shaped support strip 403 are cross-welded.

As shown in FIG. 5, the concave drum packet 406 supports the hot steam flow channel 401, the height of the concave drum packet 406 is preferably 2.5-3mm, the gap of the hot steam flow channel 401 is only 5-6mm, the gap of the cold flue gas flow channel 402 is larger, and the gap of the cold flue gas flow channel 402 does not change greatly relative to the cross section area of the flue, so the change of the flue gas flow velocity is smaller, namely the resistance drop is lower. The concave bulge 406 may be a circular truncated cone, and the resistance of the hot steam channel 401 is reduced.

The steam inlet 2 and the steam outlet 3 can be welded into a hollow semi-cylindrical round plate shell or a rectangular parallelepiped pipe box, and then are welded together with a frame, so that the steam box can bear the higher pressure of hot steam. The thickness of the plate shell is calculated according to the pressure bearing capacity reference GB150, the plate shell has the same pressure bearing capacity, the thickness of the semi-cylindrical circular plate shell is smaller than that of the plate shell of the rectangular tube box, the rectangular tube box is easier to weld due to the regular shape, and finally the most appropriate steam inlet and outlet form can be selected according to the project site and the pressure bearing capacity.

As shown in fig. 1, the steam inlet 2 and the steam outlet 3 may be hollow semi-cylindrical plate shells, which have small thickness, compact structure and space saving. The steam inlet 2 and the steam outlet 3 are provided with exhaust holes 201 at the highest positions so that the impurity gas can be discharged in time. The lowest part of the steam inlet 2 and the steam outlet 3 is provided with a liquid discharge hole 202 so as to discharge condensed liquid in the steam.

As shown in fig. 6, the flue gas heat exchanger includes a plurality of flue gas heat exchanger units 7, the plurality of flue gas heat exchanger units 7 are connected in parallel, and the number of the flue gas heat exchanger units may be 6. The housings 1 are fixed together by welding or bolting, in particular by welding together a "dish" shaped frame 102. When the smoke heat exchanger is used, the smoke heat exchanger covers and spans the middle of a flue like a cover, the space inside the flue is occupied, the space outside the flue does not need to be specially increased, and the diameter does not need to be specially thickened for ensuring the flow speed of smoke because the resistance of the heat exchanger is reduced. Thus, the space occupancy rate is reduced, and the investment cost is reduced. Specifically, the flue gas heat exchanger crosses the flue and is clamped at the flue opening by the two ends of the dish-shaped frame 102.

Example 2

In contrast to embodiment 1, the flue gas heat exchanger unit 7 further comprises a filter device 6.

As shown in fig. 1, the filtering device 6 is a wide-channel tubular heat exchange core, and includes a plurality of rows of tube bundles 601, and the filtering device 6 is directly welded on the side frame of the cold flue gas flow channel 402 on the flue gas inlet side. Specifically, the heat exchange tubes are arranged in a triangular shape to form a tube bundle 601, the number of the heat exchange tubes can be three or four, the tube bundle 601 and the tube plate 602 are welded to form the filtering device 6, and the distance between the heat exchange tubes and the heat exchange tubes is large. The filter device 6 is welded to the side frame of the cold flue gas flow path 402 on the inlet side by a connecting pipe 603.

Most of easily-scaling substances in the flue gas can be condensed on the heat exchange tubes by introducing steam into the heat exchange tubes to prevent the plates 404 from scaling, and the heat exchange tubes can better remove the scaling substances and do not influence the flow rate of the flue gas due to large space between the heat exchange tubes. Specifically, low-temperature steam is introduced into the heat exchange tube, most of easily-scaling substances carried by flue gas from the desulfurizing tower are condensed on the heat exchange tube when passing through the heat exchange tube, and the plate sheets 404 are slightly scaled after passing through the filtering device 6.

Example 3

In contrast to embodiment 1 or embodiment 2, the flue gas heat exchanger unit 7 further comprises an overhauled channel 5. Is arranged between the heat exchange core body 4 and the filtering device 6 and connects the shell 1 and the filtering device 6.

As shown in fig. 1, the maintenance channel 5 is arranged between the heat exchange core 4 and the filtering device 6, the shell 1 and the filtering device 6 are communicated, the maintenance channel 5 is welded on the side frame of the cold flue gas flow channel 402, and the filtering device 6 is directly welded on the maintenance channel 5. According to on-site actual conditions and smoke component analysis, the maintenance channel 5 can be arranged when smoke scaling is serious, on one hand, scaling conditions of the shell 1 and the filtering device 6 are favorably observed, on the other hand, scaling substances of the shell 1 and the filtering device 6 are favorably removed, and maintenance is convenient. The access way 5 is hollow structure, and hollow space is the manhole to make things convenient for people to get into the access way 5 and examine the scale deposit condition, and conveniently clear away slab and flue gas scale deposit filter equipment's structural material with high-pressure squirt etc. makes it not influence heat exchange efficiency.

Claims

1. A kind of flue gas heat exchanger, characterized by: the device comprises a plurality of flue gas heat exchanger units (7) which are connected in parallel, wherein each flue gas heat exchanger unit (7) comprises a shell (1), a steam inlet (2), a steam outlet (3) and a heat exchange core (4), the steam inlets (2) and the steam outlets (3) are arranged on two sides of a hot steam flow channel (401), and the heat exchange cores (4), the steam inlets (2) and the steam outlets (3) are fixed on the shell (1); the heat exchange core body (4) comprises a plurality of plate pairs which are stacked layer by layer, each plate pair comprises an upper plate sheet (404) and a lower plate sheet (404) which are arranged oppositely, each plate pair forms a cold flue gas flow channel (402), two adjacent plate pairs form a hot steam flow channel (401), convex bulges (405) and concave bulges (406) which are arranged in a staggered mode are arranged on the plate sheets (404), the convex bulges (405) protrude towards one side of the cold flue gas flow channel (402), and the concave bulges (406) protrude towards the other side; an omega-shaped supporting strip (403) is arranged in the cold flue gas flow channel (402), the omega-shaped supporting strip (403) is fixed on the convex bulge (405), the omega-shaped supporting strip (403) is in an omega-shaped hollow strip shape, the arrangement direction of the omega-shaped supporting strip is the same as the flue gas circulation direction in the cold flue gas flow channel (402), the height of the concave bulge (406) is 2.5-3mm, and the height range of the omega-shaped supporting strip (403) is 10-40 mm;

the flue gas heat exchanger unit (7) also comprises a filtering device (6), wherein the filtering device (6) comprises a plurality of rows of tube bundles (601) which are fixed on the air inlet side of the cold flue gas flow channel (402);

the flue gas heat exchanger unit (7) further comprises an overhaul channel (5) which is arranged between the heat exchange core body (4) and the filtering device (6) and is communicated with the shell (1) and the filtering device (6).

2. The flue gas heat exchanger of claim 1, wherein: the convex bulge (405) is an elliptical table, and the concave bulge (406) is a circular table.

3. The flue gas heat exchanger of claim 2, wherein: the distance between the convex bulges (405) is 75-85mm, and the distance between the concave bulges (406) is 35-45 mm.

4. A flue gas heat exchanger unit according to any one of claims 1-3, wherein: the steam inlet (2) and the steam outlet (3) are hollow semi-cylindrical round plate shells or hollow rectangular parallelepiped tube boxes.

5. The flue gas heat exchanger of claim 1, wherein: the shell (1) comprises a frame and two box plates (101), the box plates (101) are welded on the frame, and the frame is welded with the heat exchange core body (4); the frame comprises two dish-shaped frames (102) and four I-shaped frames (103), wherein every two I-shaped frames (103) are welded at two ends of the two dish-shaped frames (102), and the box plates (101) are respectively welded on the two dish-shaped frames (102).

6. The flue gas heat exchanger of claim 1, wherein: the highest positions of the steam inlet (2) and the steam outlet (3) are provided with exhaust holes (201), and the lowest positions of the steam inlet (2) and the steam outlet (3) are provided with liquid discharge holes (202).

7. The flue gas heat exchanger of claim 1, wherein: the thickness of the omega-shaped supporting strip (403) is 1-2 mm.