CN116428736B - Anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater - Google Patents
Anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater Download PDFInfo
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- CN116428736B CN116428736B CN202310552859.2A CN202310552859A CN116428736B CN 116428736 B CN116428736 B CN 116428736B CN 202310552859 A CN202310552859 A CN 202310552859A CN 116428736 B CN116428736 B CN 116428736B
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- 238000005260 corrosion Methods 0.000 title claims abstract description 42
- 238000005485 electric heating Methods 0.000 claims abstract description 95
- 238000010438 heat treatment Methods 0.000 claims abstract description 85
- 238000005192 partition Methods 0.000 claims abstract description 52
- 239000000428 dust Substances 0.000 claims abstract description 36
- 230000007797 corrosion Effects 0.000 claims abstract description 23
- 239000004071 soot Substances 0.000 claims description 13
- 238000003466 welding Methods 0.000 claims description 6
- 229910000640 Fe alloy Inorganic materials 0.000 claims description 5
- BIJOYKCOMBZXAE-UHFFFAOYSA-N chromium iron nickel Chemical compound [Cr].[Fe].[Ni] BIJOYKCOMBZXAE-UHFFFAOYSA-N 0.000 claims description 5
- 239000007789 gas Substances 0.000 description 31
- 239000003570 air Substances 0.000 description 29
- 238000013461 design Methods 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 239000000126 substance Substances 0.000 description 9
- 239000002253 acid Substances 0.000 description 8
- 238000009434 installation Methods 0.000 description 8
- 238000009825 accumulation Methods 0.000 description 7
- 239000003513 alkali Substances 0.000 description 7
- 238000000151 deposition Methods 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 230000008021 deposition Effects 0.000 description 6
- 230000002378 acidificating effect Effects 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 5
- 238000004939 coking Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 238000012546 transfer Methods 0.000 description 5
- 230000002349 favourable effect Effects 0.000 description 4
- 238000009991 scouring Methods 0.000 description 4
- 238000005299 abrasion Methods 0.000 description 3
- 230000002411 adverse Effects 0.000 description 3
- 238000007664 blowing Methods 0.000 description 3
- 238000011010 flushing procedure Methods 0.000 description 3
- 230000002209 hydrophobic effect Effects 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 229910001055 inconels 600 Inorganic materials 0.000 description 2
- 238000004080 punching Methods 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 150000001447 alkali salts Chemical class 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- 229910001293 incoloy Inorganic materials 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H3/00—Air heaters
- F24H3/02—Air heaters with forced circulation
- F24H3/04—Air heaters with forced circulation the air being in direct contact with the heating medium, e.g. electric heating element
- F24H3/0405—Air heaters with forced circulation the air being in direct contact with the heating medium, e.g. electric heating element using electric energy supply, e.g. the heating medium being a resistive element; Heating by direct contact, i.e. with resistive elements, electrodes and fins being bonded together without additional element in-between
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H9/00—Details
- F24H9/18—Arrangement or mounting of grates or heating means
- F24H9/1854—Arrangement or mounting of grates or heating means for air heaters
- F24H9/1863—Arrangement or mounting of electric heating means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H9/00—Details
- F24H9/40—Arrangements for preventing corrosion
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chimneys And Flues (AREA)
- Direct Air Heating By Heater Or Combustion Gas (AREA)
Abstract
The application relates to the technical field of electric heaters, in particular to an anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater, which comprises n layers of vertically arranged partition boards, wherein the n layers of partition boards divide the inner cavity of a shell of the electric heater into n+1 channels which are communicated in an S shape in sequence, and an electric heating pipe penetrates through all the partition boards; the top of the first channel is provided with a heating medium inlet, and the top or the side wall of the last channel is provided with a heating medium outlet; the partition plate is of a special-shaped structure, and the wall surface of the partition plate is inclined towards the heating medium. The electric heater has the advantages of simple structure, small volume, high heat exchange efficiency, difficult blockage and corrosion, and well solves the problem that equipment cannot stably run for a long time due to blockage and corrosion of dust.
Description
Technical Field
The application relates to a method for producing a water, dust and acid Substance (SO) 2 An HCl/HF) gas heating medium, in particular to an anti-blocking anti-corrosion air duct type electric heater with high-efficiency heat exchange.
Background
An electric heater is a device capable of converting electric energy into heat energy, and is used for heating and preserving heat of gas or liquid. When the heating medium flows through the electric heater, the fluid takes away the heat of the electric heating tube through heat exchange, so that the heating medium reaches the temperature requirement required by a user. The air duct type electric heater is one of important types of electric heaters, is mainly used for heating air, and the pressure of the heated air is generally not more than 0.3kg/cm 2 The method is widely applied to the fields of waste gas treatment, chemical industry and the like. Because the air components are relatively single, the conventional air duct type electric heater can meet the process requirements without considering a plurality of influencing factors when being designed; in the case of a gaseous heating medium containing water, dust and acidic substances, the water, dust and acidic substances are used as the heating medium,The acidic substances can obviously damage the electric heater, so that the design of the air duct type electric heater needs to fully consider the influences of the factors to ensure the long-term stable and efficient operation of the equipment.
Firstly, the design of the electric heater fully considers the adverse effect of dust in a heating medium on the electric heater, so that the proper transverse distance between the electric heating tubes is selected. In order to enhance the heat transfer effect and increase the gas flow rate, the conventional air duct type electric heater is generally compact in arrangement of electric heating tubes, and the transverse spacing of the electric heating tubes is small, but for heating dust-containing gas, the too small transverse spacing of the electric heating tubes can cause ash accumulation and blockage among the electric heating tubes, so that the flow resistance is increased, and the operation is unstable; it is therefore necessary to design a larger lateral spacing of the electrical heating tubes to reduce the risk of ash build-up. Although the use of a larger spacing between the electrical heating tubes can significantly improve ash deposition and clogging, the gas flow rate of the heating medium can be greatly reduced, resulting in a poor heat exchange effect between the heating medium and the electrical heating tubes. In order to meet the temperature required by the process of heating the medium, more electric heating pipes are often required to be arranged for heating the medium, so that the equipment is huge, the installation and arrangement are inconvenient, and the investment cost is high.
Secondly, the design of the electric heater fully considers the adverse effect of dust coking and high-temperature corrosion on the electric heater, and particularly when the dust in the heating medium contains high-concentration alkali (K/Na) and alkaline-earth (Mg/Ca) salts, the problems of dust accumulation and blockage of the electric heater and the coking and high-temperature corrosion of the electric heater are accompanied. The alkali salt has low melting point and strong corrosiveness, and when the temperature of the wall surface of the electric heating tube is more than or equal to 700 ℃, softening and adhering are started and high-temperature corrosion occurs; and the higher the wall temperature of the electric heating tube is, the more serious the coking and high-temperature corrosion problems are. The alkali ash is firmly adhered to the electric heating tube, and is difficult to be cleaned by a general soot blower, so that the electric heater is forced to be stopped for maintenance, and manual cleaning is carried out; in addition, the adhesive ash increases the dirt heat resistance in the heat transfer process, the heat transfer is further deteriorated, the heat energy released by the electric heating tube cannot be taken away by a heating medium, the overtemperature of the electric heating tube is alarmed, and the service life of the electric heating tube is greatly reduced.
Finally, when two or three substances of high content of water, dust and acid gas exist in the heating medium at the same time, superposition and interaction can also occur between the two or three substances, so that the damage of the electric heater is further aggravated. When the heating medium contains water and alkali ash, the alkali ash absorbs water and deliquesces when the local temperature of the equipment is low or the equipment is stopped, and is hardened in the pipeline of the equipment, so that the equipment is difficult to clean. When the heating medium contains water + acid gas, some heating medium remains in the apparatus when the electric heater is shut down, and at temperatures below the acid dew point, the acid gas and water condense to form an acid solution, resulting in low temperature corrosion.
Therefore, for heating the gas medium containing water, dust and acidic substances, the existing air duct type electric heater has the problems of ash accumulation and blockage, high temperature and low temperature corrosion and low heat exchange efficiency, and the use requirements of efficient heat exchange and stable operation cannot be met, so that the air duct type electric heater with anti-blocking, anti-corrosion and efficient heat exchange needs to be designed to solve the problems.
Disclosure of Invention
The application aims to provide an anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater, which has the advantages of simple structure, small volume, high heat exchange efficiency and difficult blockage and corrosion for heating a gas medium containing water, dust and acidic substances, and well solves the problem that equipment cannot stably run for a long time due to blockage and corrosion of dust.
In order to solve the technical problems, the technical scheme provided by the application is as follows:
an anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater comprises n layers of vertically arranged partition boards, wherein the n layers of partition boards divide an inner cavity of an electric heater shell into n+1 channels which are communicated in an S shape in sequence, and an electric heating pipe penetrates through all the partition boards; the top of the first channel is provided with a heating medium inlet, and the top or the side wall of the last channel is provided with a heating medium outlet; the partition board is of a special-shaped structure, the wall surface of the partition board inclines towards the direction of the heating medium, the flowing direction of gas can be changed, and a flowing field which is favorable for heat exchange of the electric heater is molded.
When a single baffle is used, the heating medium outlet is provided at the top or side wall of the last channel; when the double-number partition plates are adopted, the heating medium outlet is arranged on the side wall of the last channel; such as: the shell is divided into 2 channels by the 1-layer partition board, the top of the first channel is a heating medium inlet, and the top or the side wall of the second channel is a heating medium outlet; the shell is divided into 3 channels by the 2 layers of partition boards, the top of the first channel is provided with a heating medium inlet, and the side wall of the lower part of the third channel is provided with a heating medium outlet; the shell is divided into 4 channels by the 3 layers of partition boards, the top of the first channel is a heating medium inlet, and the top or the side wall of the fourth channel is a heating medium outlet; and so on.
Each partition plate is formed by sequentially welding two tube-side comb-shaped plates positioned at the left end and the right end and a plurality of inter-tube comb-shaped plates positioned between the two tube-side comb-shaped plates, and one side of each tube-side comb-shaped plate is provided with semicircular openings which are equal to the number of the electric heating tubes in each row and correspond to the positions of the electric heating tubes; semicircular openings which are equal to the electric heating tubes in number in each row and correspond to the electric heating tubes in position are arranged on two sides of the comb-shaped plate between the tubes; the diameter of a round hole formed by enclosing the semicircular openings of the tube side comb-shaped plates or the tube-to-tube comb-shaped plates is slightly larger than the outer diameter of the electric heating tube.
The baffle adopts the comb-shaped plate structure to support the electric heating tube. The design mode solves the installation problem of the multi-elbow electric heating tube, the electric heating tube cannot penetrate through the common punching partition plate due to the existence of the elbow, and the convenient installation of the multi-elbow electric heating tube is well realized by adopting the sparse plate structure.
Wherein, the specific setting number of the partition plates is to comprehensively consider the factors such as heat transfer efficiency, flow resistance, abrasion and the like between the heating medium and the equipment, and the setting number of the partition plates is preferably 5 m/s-10 m/s of the flow velocity of the heating medium.
The partition board is arc-shaped, so that the flowing direction of gas can be changed, a flow field favorable for heat exchange is molded, and the heat exchange efficiency of the electric heating pipe is improved.
The included angle between the flow direction of the heating medium and the axial direction of the electric heating tube is 90 degrees, so that the electric heating tube is transversely flushed by air flow, and the heat exchange efficiency of the electric heater is enhanced.
Wherein the electric heating pipes are arranged in parallel at equal intervals, and the transverse interval between two adjacent rows of electric heating pipes is more than or equal to 100mm; the wider space between the transverse pipes and the arrangement mode in the sequence are beneficial to ash falling between the pipes, so that the bridging and blockage of dust between the electric heating pipes are avoided.
The side surface of the pipeline of the heating medium inlet is provided with an air switching port, the switching of the heating medium and air is realized through the three-way valve, and the heating medium can be used for replacing residual heating medium during normal shutdown or failure, so that the residual heating medium is prevented from condensing and then causing low-temperature corrosion and moisture absorption hardening of dust.
Wherein, the lower part of the heating medium inlet is provided with an even distributor, the even distributor adopts a guide vane structure which is not easy to accumulate ash, and the blades are arranged in a divergent mode; the heated gas is fully and uniformly distributed on the heat exchange surface of the electric heating tube through the uniform distributor, so that the heat exchange efficiency of the electric heater is improved.
The side face of each channel is provided with a soot blower, the purging frequency is set according to the blocking condition of the electric heater, the electric heater is periodically purged and ash removed on line, and the bypass and deposition of dust on the electric heater are avoided; the position of the soot blower is set so that the high-pressure air flow sprayed by the soot blower is swept onto the electrothermal tube in the largest area.
Wherein, the below of every passageway is equipped with the dust and collects the bucket for collect the subsidence ash of heating medium in the flow in-process, make subsidence dust in time discharge equipment, avoid piling up the jam equipment.
The design of the electric heating tube selects smaller wall temperature to reduce the risks of coking and high-temperature corrosion of the alkali ash, and the wall temperature of the electric heating tube is preferably less than or equal to 700 ℃; the electrothermal tube is made of nickel-chromium-iron alloy resistant to high temperature and low temperature corrosion, so that the electrothermal tube can not only resist high temperature, but also has certain high temperature and low temperature corrosion resistance.
The bottom of the electric heater is provided with a supporting frame for supporting each channel and the electric heating tube, and flexible arrangement and installation can be realized according to the on-site conditions.
Compared with the prior art, the anti-blocking anti-corrosion efficient heat exchange air duct type electric heater has at least the following beneficial effects:
(1) The anti-blocking anti-corrosion efficient heat exchange air duct type electric heater device has the advantages of simple and compact structure, small volume, low cost and high stability;
(2) The arrangement of the partition plate obviously increases the flow rate of the heating gas and obviously enhances the heat exchange capacity of the electric heater; the separator is of a special-shaped structure, the flowing direction of a gas heating medium is changed, a flow field beneficial to heat exchange is molded, and the heat exchange efficiency of the electric heating pipe is improved;
(3) The baffle adopts the comb-shaped plate structure to support the electric heating tube, so that the convenient installation of the multi-elbow electric heating tube is well realized.
(4) The heating gas transversely washes the electric heating tube, so that the heat exchange efficiency of the electric heater is improved;
(5) The equidistant inline arrangement and the reasonable design of the distance between the electric heating tubes reduce the risk of dust bridging and blocking between the tubes;
(6) The arrangement of the air switching port replaces the residual heating medium with air, so that low-temperature corrosion of the electric heater and moisture absorption hardening of dust are avoided;
(7) The heating medium inlets are provided with the uniform distributor, so that the gas heating medium is uniformly distributed on the electric heating tube, and the heat exchange efficiency of the electric heater is improved;
(8) The soot blower is arranged to realize online ash removal, so that the risks of bridging and depositing dust on the electric heating tube are reduced;
(9) The dust collecting hopper is arranged, so that deposited dust is discharged in time, and the equipment is prevented from being blocked by dust accumulation;
(10) The design of the electric heating tube selects the mild nickel-chromium-iron alloy material with smaller wall, thereby further enhancing the high-temperature and low-temperature corrosion resistance of the equipment.
The anti-blocking anti-corrosion efficient heat exchange air duct type electric heater is further described below with reference to the accompanying drawings.
Drawings
FIG. 1 is a schematic diagram of the overall structure of an anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater;
FIG. 2 is a cross-sectional view taken in the direction "A-A" of FIG. 1;
FIG. 3 is a schematic view of a partial structure of the "B-B" separator shown in FIG. 2;
FIG. 4 is a schematic view of the tube side comb plate and inter-tube comb plate of FIG. 3;
fig. 5 is a cross-sectional view taken along the direction "C-C" in fig. 3.
Wherein: 1-partition plate, 2-shell, 3-first channel, 4-second channel, 5-third channel, 6-electrothermal tube, 7-heating medium inlet, 8-heating medium outlet, 9-air switching port, 10-distributor, 11-soot blower, 12-dust collecting bucket, 13-support frame, 14-tube side comb plate, 15-tube comb plate, 16-weld joint and 17-expansion gap.
Detailed Description
As shown in fig. 1-2, taking the case of two layers of clapboards as an example, an anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater comprises two layers of clapboards 1 which are vertically arranged, wherein the two layers of clapboards 1 divide the inner cavity of an electric heater shell 2 into 3 channels which are sequentially communicated in an S shape, namely a first channel 3, a second channel 4 and a third channel 5, and an electric heating tube 6 penetrates through the two layers of clapboards 1; the top of the first channel 3 is provided with a heating medium inlet 7, and the side wall of the lower part of the third channel 5 is provided with a heating medium outlet 8; the heating medium flows in from the heating medium inlet 7, exchanges heat with the electric heating tube 6, reaches the process required temperature, and is discharged from the heating medium outlet 8.
The side of each channel is provided with a soot blower 11, and the electric heater is periodically purged and cleaned on line. The frequency of the blowing of the soot blower 11 may be determined according to the soot deposition level of the electric heater. Differential pressure transmitters are arranged at the inlet and the outlet of the electric heater, and the differential pressure of the electric heater is monitored on line. When the electric heater has obvious pressure difference increase in a short time, the existence of dust deposition blockage is indicated, the soot blowing frequency can be increased, the timely soot cleaning is realized, and the blockage caused by the continuous accumulation of dust is avoided.
The dust collecting hopper 12 is arranged below each channel and is used for collecting the sedimentation ash of the heating medium in the flowing process, so that the sedimentation ash can be discharged in time, and the equipment is prevented from being blocked by accumulation. In order to maintain self-fluidity of the settled ash in the ash bucket, the inclination angle of the ash bucket is more than or equal to 50 degrees (the included angle with the horizontal direction).
The design quantity of the partition boards 1 obviously influences the performance parameters such as heat exchange efficiency, flow resistance and the like of the electric heater. The number of the partition boards is small, the flow speed of the heating medium is low, and the convection heat exchange efficiency is low; and the flow speed is too low, the carrying force of the airflow on dust is weak, and the inter-pipe bridging and deposition are easy to occur. Although the arrangement of more baffles can obviously increase the flow rate of gas, thereby enhancing the heat exchange between the gas and the electric heating tube, dust can be carried and discharged well, but too high flow rate can obviously increase the flow resistance of the gas and the abrasion of the electric heating tube; this is because the flow resistance is proportional to the square of the media flow rate and the wall wear is proportional to the third power of the media flow rate. Therefore, the number of the partition plates is designed according to the flow rate of the heating medium of 5-10 m/s, and the number of the partition plates is the final optimal choice taking the factors such as heat transfer efficiency, ash accumulation, flow resistance, abrasion and the like into consideration.
The partition board 1 adopts a special-shaped structure instead of a conventional vertical partition board, because the vertical partition board is adopted, when the gas flows in a 180-degree large turning direction, the gas tends to deflect to the outer wall side due to inertia force, so that an obvious bias flow phenomenon is formed, the electric heating pipe 6 close to the inner wall side cannot be fully contacted and flushed by the heated gas, the utilization rate of the electric heating pipe 6 is reduced, and adverse effects on heat exchange are caused. The conventional air duct type electric heater rarely considers the problem of low utilization rate of a heating surface caused by bias flow of heating gas, so that the application is provided with the partition plate 1 with a special-shaped structure, and aims to change the flow direction of the gas, shape a gas flow field favorable for heat exchange and improve the utilization rate and heat exchange efficiency of the electric heating pipe 6.
Preferably, the partition board 1 can adopt an arc structure, as shown in fig. 1, the partition board 1 at the inlet and outlet of each channel inclines towards the direction of flowing gas, so that the flowing gas is forced to turn at a certain angle when flowing at the position, and the electrothermal tube 6 at the inlet and outlet is fully flushed by heating medium, thereby improving the utilization rate of the electrothermal tube. Although the smaller the inclination angle (the included angle between the tangent line of the cambered surface and the horizontal direction) of the partition plate 1, the more obvious the deflection degree of the incoming gas is, and the more favorable the flushing heat exchange of the electric heating tube is, the inclination angle cannot be too small, and the risk of dust deposition on the partition plate exists due to the too small inclination angle, so that the inclination angle is more than or equal to 60 degrees, and the ash can flow automatically and fall into the dust collecting bucket 11.
The partition plate 1 adopts a comb-shaped plate structure to support the electric heating tube 6, as shown in figures 3, 4 and 5. The electric heating tube 6 can be U-shaped or W-shaped electric heating tube.
Each partition plate 1 is formed by welding two tube side comb-shaped plates 14 located at the left and right ends and a plurality of inter-tube comb-shaped plates 15 located between the two tube side comb-shaped plates 14 in sequence. One side of the tube side comb-shaped plate 14 is provided with semicircular openings which are equal to the number of the electrothermal tubes 6 in each row and correspond to the positions of the electrothermal tubes 6; semicircular openings which are equal in number to each row of electric heating tubes 6 and correspond to the electric heating tubes 6 in position are formed in two sides of the inter-tube comb-shaped plate 15; the diameter of a round hole formed by surrounding the semicircular openings of the tube side comb-shaped plates 14 or the tube-to-tube comb-shaped plates 15 is slightly larger than the outer diameter of the electric heating tube 6.
The tube-side comb-shaped plate 14 is arranged at the outer side of the most edge row of electric heating tubes 6, wherein one side with a semicircular opening is matched with the electric heating tubes 6, and the other side is connected with a backing plate on the shell 2; the tube-to-tube hydrophobic plates 15 are arranged between two adjacent rows of electric heating tubes 6, both sides of the tube-to-tube hydrophobic plates are provided with semicircular openings, and when the two comb-shaped plates are butted together, a whole round hole is formed, and the electric heating tubes can be perforated. When the electric heating tube 6 is installed, each row of electric heating tubes 6 and each comb-shaped plate 14 or 15 are assembled in a row, and the assembled electric heating tubes 6 realize the position fixation of the electric heating tubes 6 by welding the upper and lower welding seams 16 of each round hole of the comb-shaped plate 14 or 15. The design of the comb-shaped plate solves the installation problem of the multi-elbow electric heating tube, such as a common W-shaped electric heating tube, and a 3-elbow is formed after one electric heating tube is bent into a W shape, and the electric heating tube cannot pass through a common punching partition plate due to the existence of the elbow; and the adoption of the hydrophobic plate structure does not have the problem of elbow perforation, and the convenient installation of the multi-elbow electric heating tube is well realized. The electrothermal tube 6 will quickly rise in temperature and expand after being electrified, so the radius R of a round hole formed by butting the comb-shaped plates 14 and 15 is slightly larger than the radius R of the electrothermal tube, delta=R-R is an expansion gap 17, and the size of the expansion gap 17 is determined by factors such as the temperature of the electrothermal tube and the material quality.
The two tube side comb-shaped plates 14 and the plurality of tube comb-shaped plates 15 are combined into the baffle plate 1, the electric heating tube 6 is supported on the baffle plate 1, the upper end and the lower end of the baffle plate 1 are connected with the shell 2 through supporting legs and backing plates, and the shell 2 is supported on the supporting frame 13, so that the whole electric heater is supported. As supported by a first partition board 1 in fig. 1, an outlet of the heating medium is positioned at the bottom of the shell, the upper end of the partition board 1 is connected with a top backing board, and the top backing board is connected with the shell 2; the lower end of the partition board 1 can be provided with 2 to 5 supporting legs at symmetrical positions of two sides or the middle and the like, the lower end of the partition board 1 is connected with the supporting legs, the supporting legs are connected with a bottom backing plate, and the bottom backing plate is connected with the shell 2; similarly, for the second partition board connection in fig. 1, the lower end of the partition board 1 is connected with a bottom pad, and the bottom pad is connected with the shell 2; the upper end of the partition board 1 is connected with supporting legs, the supporting legs are connected with top backing plates, and the top backing plates are connected with the shell 2, so that firm connection between the upper end and the lower end of the partition board and the shell is realized.
The included angle between the flow direction of the heating medium and the axial direction of the electric heating tube 6 is 90 degrees. The transverse flushing means that the flow direction of the heating medium is arranged at 90 degrees with the axial direction of the electric heating tube 6, and the longitudinal flushing means that the flow direction of the heating medium is arranged at 0 degrees with the axial direction of the electric heating tube 6. The heat exchange coefficient of the transverse scouring is obviously higher than that of the longitudinal scouring, because the heat boundary layer of the transverse scouring is thin and has vortex generated due to boundary layer separation, the disturbance of fluid is increased, the convection heat exchange is facilitated, and the heat boundary layer of the longitudinal scouring is thicker and is not easy to damage, so that the heat resistance is high, and the convection heat exchange is not facilitated.
The electric heating tubes 6 are arranged in parallel at equal intervals. When the flue gas transversely washes the electric heating tube bundles, the arrangement mode of the bundles is two modes of sequential arrangement and staggered arrangement; the arrangement mode in the sequence is more beneficial to the ash falling between pipes and the blowing ash removal of the soot blower; the staggered arrangement mode can make the structure more compact, but dust is more likely to bridge between pipes and accumulate dust, and the pipe wall is more severely worn. The transverse spacing between two adjacent rows of electric heating tubes 6 has obvious influence on ash falling, and the larger transverse spacing is beneficial to ash falling between the tubes, so that the transverse spacing S1 is preferably more than or equal to 100mm; the longitudinal spacing between the upper and lower adjacent electric heating tubes 6 has little influence on ash falling, the bending radius of the electric heating tubes 6 determines the size of the longitudinal spacing, and the bending radius is generally not smaller than 2.5 times of the tube diameter.
An air switching port 9 is formed in the side face of the pipeline of the heating medium inlet 7, and the switching between the heating medium and the air is realized by the aid of a three-way valve through sucking ambient air, so that when equipment is normally stopped or fails, the residual heating medium is replaced by the air, and low-temperature corrosion and dust hardening caused by condensation of the residual heating medium are avoided.
An even distributor 10 is arranged below the heating medium inlet 7, the even distributor 10 adopts a guide vane structure, and the blades are arranged in a divergent mode. The heated gas is forced to be fully and uniformly guided and distributed on the electric heating tube by the action of the uniform distributor to exchange heat, so that the utilization rate of the electric heating tube is improved.
The electrothermal tube 6 should be selected to have a smaller wall temperature, the wall temperature of the electrothermal tube 6 is mainly determined by the surface load and the heat exchange environment, and the design can be selected to have a lower surface load (less than or equal to 3W/cm) 2 ) And higher medium flow speed (more than or equal to 5 m/s) to reduce the temperature of the tube wall of the electric heating tube. The wall temperature of the electric heating tube can be measured by directly welding the thermocouple on the tube wall, so that the measurement accuracy is high, and the error is not more than +/-5%. When the temperature measured value of the thermocouple is higher than the set value of the pipe wall temperature by 700 ℃, the electric heating pipe 6 alarms in an overtemperature mode or the equipment fails to stop, so that the automatic interlocking protection of the equipment is realized, and the risks of coking and high-temperature corrosion of the electric heating pipe 6 by the alkali ash are reduced.
In order to have certain high and low temperature corrosion resistance and prevent overheating burnout caused by the increase of ash and scale thermal resistance, the electrothermal tube 6 is preferably made of nickel-chromium-iron alloy, for example: incoloy840 (Ni: 20%), incoloy 800 (Ni: 30-35%), inconel600 (Ni: 72%). Nickel content in the nickel-chromium-iron alloy is higher than that of stainless steel, so that the corrosion resistance to acid, alkali, sulfur and the like is better than that of the stainless steel, and particularly Inconel600 has excellent chlorine corrosion resistance and excellent corrosion resistance to heating media containing hydrogen chloride (HCl) acid gas.
The bottom of the electric heater is provided with a supporting frame 13 for supporting the electric heater, and flexible arrangement and installation can be realized according to the situation of the site.
The above examples are only illustrative of the preferred embodiments of the present application and are not intended to limit the scope of the present application, and various modifications and improvements made by those skilled in the art to the technical solution of the present application should fall within the scope of protection defined by the claims of the present application without departing from the spirit of the present application.
Claims (7)
1. An anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater is characterized in that: the electric heater comprises n layers of vertically arranged partition plates (1), wherein the n layers of partition plates (1) divide the inner cavity of an electric heater shell (2) into n+1 channels which are communicated in an S shape in sequence, and an electric heating tube (6) penetrates through all the partition plates (1); the top of the first channel is provided with a heating medium inlet (7), and the top or the side wall of the last channel is provided with a heating medium outlet (8); the partition board (1) is of a special-shaped structure, and the wall surface of the partition board (1) inclines towards the direction of the heating medium; the partition board (1) is arc-shaped, and the inclination angle of the partition board is more than or equal to 60 degrees;
each partition plate (1) is formed by sequentially welding two pipe-edge comb-shaped plates (14) positioned at the left end and the right end and a plurality of inter-pipe comb-shaped plates (15) positioned between the two pipe-edge comb-shaped plates (14); one side of the tube side comb-shaped plate (14) is provided with semicircular openings which are equal to the number of the electric heating tubes (6) in each row and correspond to the positions of the electric heating tubes (6); semicircular openings which are equal to the electric heating pipes (6) in number in each row and correspond to the electric heating pipes (6) in position are arranged on two sides of the comb-shaped plates (15) between the pipes; the diameter of a round hole formed by surrounding semicircular openings of the tube side comb-shaped plates (14) or the tube-to-tube comb-shaped plates (15) is slightly larger than the outer diameter of the electric heating tube (6); the side of each channel is provided with a soot blower (11), and the lower part of each channel is provided with a dust collecting bucket (12).
2. The anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater according to claim 1, wherein: the included angle between the flow direction of the heating medium and the axial direction of the electric heating tube (6) is 90 degrees.
3. The anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater according to claim 1, wherein: the electric heating tubes (6) are arranged in parallel at equal intervals, and the transverse distance between two adjacent rows of electric heating tubes (6) is more than or equal to 100mm.
4. The anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater according to claim 1, wherein: an air switching port (9) is formed in the side face of the pipeline of the heating medium inlet (7), and switching between the heating medium and air is achieved through a three-way valve.
5. The anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater according to claim 1, wherein: the lower part of the heating medium inlet (7) is provided with an even distributor (10), the even distributor (10) adopts a guide vane structure, and the blades are arranged in a divergent mode.
6. The anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater according to claim 1, wherein: the flow speed of the heating medium is 5 m/s-10 m/s; the wall surface temperature of the electric heating tube (6) is less than or equal to 700 ℃, and the electric heating tube (6) is made of nickel-chromium-iron alloy resistant to high temperature and low temperature corrosion.
7. The anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater according to claim 1, wherein: the bottom of the electric heater is provided with a supporting frame (13).
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| CN202310552859.2A CN116428736B (en) | 2023-05-17 | 2023-05-17 | Anti-blocking and anti-corrosion efficient heat exchange air duct type electric heater |
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| CN218065361U (en) * | 2022-07-11 | 2022-12-16 | 长沙欧鑫科技有限公司 | Electrical heating tail gas processor |
| CN218820990U (en) * | 2022-11-02 | 2023-04-07 | 阿特拉斯·科普柯(无锡)压缩机有限公司 | Heating device |
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| CN201731623U (en) * | 2010-05-04 | 2011-02-02 | 潍坊市润捷轻工环保科技有限公司 | Hot air furnace |
| CN202101596U (en) * | 2011-04-22 | 2012-01-04 | 中国石油化工股份有限公司 | Tube and shell type heat exchanger |
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| CN116428736A (en) | 2023-07-14 |
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