CN111140834A - Three-coil gas flue gas turbulent flow heat exchange device and method - Google Patents
Three-coil gas flue gas turbulent flow heat exchange device and method Download PDFInfo
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- CN111140834A CN111140834A CN202010042991.5A CN202010042991A CN111140834A CN 111140834 A CN111140834 A CN 111140834A CN 202010042991 A CN202010042991 A CN 202010042991A CN 111140834 A CN111140834 A CN 111140834A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B31/00—Modifications of boiler construction, or of tube systems, dependent on installation of combustion apparatus; Arrangements of dispositions of combustion apparatus
- F22B31/08—Installation of heat-exchange apparatus or of means in boilers for heating air supplied for combustion
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
- F28D7/04—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being spirally coiled
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/30—Technologies for a more efficient combustion or heat usage
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Abstract
The invention relates to a three-coil gas flue gas turbulent flow heat exchange device and a method, wherein the device takes a burner, an inner layer circular coil, a middle layer circular coil and an outer layer flat coil as main bodies, the design of the inner layer, the middle layer and the outer layer three layers of coils is adopted, light pipe coils at two layers of the inner middle part are arranged in a staggered way to form a radiation closed hearth, the outer layer adopts the flat coil to cool and condense flue gas, and the heat efficiency of a boiler is effectively improved; when the condensation flue gas is cooled, the viscous resistance of the flue gas is increased, the flowing state of the flue gas is changed from turbulent flow to laminar flow, the heat exchange coefficient is increased, and the cooling and condensation capacity of the flue gas is enhanced. And inlayer circle coil pipe and middle level circle coil pipe staggered arrangement form radiation confined furnace, according to radiation fourth power law, can absorb the radiant heat to the flue gas by a wide margin that is discharged by the combustor, compare the flat coil heat transfer wall of a return journey of present in service, manufacturing process is simpler, and heat transfer coil pipe is compacter, and cost is cheaper.
Description
Technical Field
The invention relates to the technical field of enhanced heat transfer, high efficiency and energy conservation, in particular to a three-coil gas flue gas turbulent flow heat exchange device and a method.
Background
Natural gas is widely used as a clean and environment-friendly high-quality energy source, and a gas coil boiler is also required for future development trend as an energy-saving and environment-friendly product. The prior gas coil boiler has the advantages that firstly, two heat exchange coils are arranged independently and stacked together, and only a single coil exchanges heat during operation, so that the heat efficiency is low and the energy of the single coil cannot be used as much as possible; secondly, the arranged inner and outer layer coil pipes are flat coil pipes, the manufacturing process of the hydraulic formed flat coil pipes is complex, a steel plate is adopted to roll and weld the flat coil pipes into round pipes, then the round pipes are subjected to cold machining and extrusion deformation to form long circular section flat pipes, the straight flat pipes are subjected to cold machining and wound into coil pipes, and finally stress relief annealing is carried out to obtain finished coil pipe units; the cold processing deformation in the coil pipe processing is large, and residual stress and lattice defects exist; the processing technology is complicated, the yield is low, the number of turns of the coil pipe must be increased to reduce the gap between the coil pipes, and therefore the total heat exchange area of the coil pipe and the weight of the boiler are greatly increased; thirdly, the traditional gas coil boiler has the problems of large heat exchanger volume, large smoke and wind resistance, high initial investment and operation cost and incapability of meeting the requirement of smoke exhaust temperature in the occasions with special requirements on heat exchange quantity, and is difficult to be applied.
In addition, every 1m3The combustion products of natural gas (methane accounting for about 85%) have about 2.1-2.3 m3The latent heat steam is converted according to the heat value of natural gas of 8000-8500 kilocalories per cubic meter and the latent heat of water vapor of 0.1MPa and 100 ℃ of 2257kj/kg, and the latent heat loss of the steam in low-level heating value accounts for the total heat of combustion of the natural gasThe quantity is 9.57%, and the existing boiler can not fully utilize the heat, so that the demand of the gas boiler on natural gas is always high, and huge energy loss is caused.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a three-coil gas flue gas turbulent flow heat exchange device and a three-coil gas flue gas turbulent flow heat exchange method, which have the advantages of simple structure and reasonable design, effectively improve the heat efficiency of a boiler, simultaneously can dilute harmful substances in flue gas, reduce the use amount of gas, reduce the price and the operating cost of a coil gas boiler, save energy, reduce emission and cost, and promote the development of the coil gas boiler technology.
The invention is realized by the following technical scheme:
a three-coil gas flue gas turbulent flow heat exchange device comprises a shell, an inner layer circular coil, a middle layer circular coil and an outer layer flat coil which are coaxially arranged in the shell, and a burner which is inserted into the upper end of the shell along the axis;
the lower end of the shell is communicated with a smoke outlet, the upper end of the shell is provided with an upper cover plate, and the interior of the shell is provided with a lower cover plate; the upper and lower ends of the inner layer circular coil pipe, the middle layer circular coil pipe and the outer layer flat coil pipe are respectively arranged with the upper and lower cover plates in a sealing way;
the heat exchange tubes of the inner layer circular tube and the middle layer circular tube are arranged in a staggered manner to form a radiation closed hearth; a gap between the inner layer coil pipe and the middle layer coil pipe is formed between the inner layer coil pipe and the middle layer coil pipe; two ends of the inner layer disc pipe and the middle layer disc pipe are respectively connected with the inner layer header;
the inner side of the outer layer flat coil pipe and the middle layer coil pipe are arranged intermittently, the outer side of the outer layer flat coil pipe and the inner wall of the shell are arranged in a clearance mode to form a near-wall surface flue gas channel, and the adjacent heat exchange pipes are directly arranged in the clearance of the flat coil pipes; the near-wall surface smoke channel is communicated with the smoke outlet; two ends of the outer-layer flat coil pipe are respectively connected with an outer-layer header; the gap between the flat coil pipes is smaller than that between the inner and middle coil pipes;
the outer layer header backwater inlet of the outer layer header is arranged outside the shell and serves as the backwater inlet of the heat exchange device, the outer layer header outlet is connected with the inlet of the inner layer header, and the inner layer header backwater outlet of the inner layer header is arranged outside the shell and serves as the backwater outlet of the heat exchange device.
Preferably, the inner layer circular coil pipe and the middle layer circular coil pipe have the same screw pitch, the same pipe diameter and the same wall thickness; the thread pitch of the inner layer disc pipe and the middle layer disc pipe is 40 mm-64 mm, the pipe diameter is 24 mm-44 mm, and the wall thickness is 1.5 mm-3 mm; the spiral radius of the inner layer circular coil pipe is 320 mm-580 mm, and the spiral radius of the middle layer circular coil pipe is 370 mm-650 mm; the inner layer circular disk tube and the middle layer circular disk tube form two rows of staggered hearth water-cooled walls with the same transverse pitch and thread pitch and the longitudinal pitch smaller than the thread pitch; the inner layer disc pipe and the middle layer disc pipe are respectively of a multi-pipe-ring parallel structure, and a parallel structure is also adopted between the inner layer disc pipe and the middle layer disc pipe.
Preferably, the cross section of the burner is circular, the diameter of the burner is 60 mm-350 mm, and the length of the burner is 450 mm-780 mm; the outer surface of the combustion head and the inner surface of the inner layer disk tube reserve a contact space of 45 mm-950 mm.
Preferably, the inner layer header is arranged between the middle layer round coil pipe and the outer layer flat coil pipe; the circular pipes at the two ends of the inner layer circular coil pipe gradually become elliptical pipes when the pipe turns outwards at 90 degrees, and extend out of the gap between the two circles of the middle layer circular coil pipe to be connected with the inner layer header; the two ends of the middle layer round coil pipe are connected with the inner layer header through 90-degree outward turning.
Preferably, the outer-layer header is arranged on the outer wall surface of the shell, and two ends of the outer-layer flat coil pipe are respectively connected with the outer-layer header through 90-degree elbows; the inner layer circular coil pipe, the middle layer circular coil pipe and the outer layer flat coil pipe form a water inlet and a water outlet which are positioned on the same plane.
Preferably, the outer shell comprises a furnace body section arranged in a cylindrical shape and a reducing section arranged in an inverted cone shape; a lower cover plate is arranged between the furnace body section and the reducing section, and refractory mortar is wrapped on the lower cover plate; the inner layer round coil pipe, the middle layer round coil pipe and the outer layer flat coil pipe are supported on the lower cover plate and are arranged in the furnace body section; the near-wall surface smoke channel is connected with the smoke outlet through the reducing section.
Preferably, the inner-layer circular coil pipe, the middle-layer circular coil pipe and the outer-layer flat coil pipe are respectively provided with 1-40 coil pipe units, and the number of turns of each coil pipe unit is 1-50; the upper and lower coil pipe units of outer flat coil pipe stack the setting, and the gap between the coil pipe unit sets up locating pad, location broach or bulge and fix a position.
Preferably, the backwater inlet of the outer layer header is arranged at the upper end of the outer layer header and is communicated with the outer water inlet collecting cavity, the outer water outlet collecting cavity is communicated with an elbow arranged at the lower end of the outer layer header, and the elbow is communicated with the inlet arranged at the lower end of the inner layer header; the inlet of the inner-layer header is communicated with the inner water inlet collecting cavity, the return water outlet of the inner-layer header is communicated with the inner water outlet collecting cavity through a bent pipe passing through the shell, and the connecting end of the bent pipe is arranged at the lower end of the inner-layer header;
the cooling water in the outer layer flat coil pipe is all in and out from the top, and the cooling water in the inner layer disc pipe and the middle layer disc coil pipe is all in and out from the bottom.
A three-coil gas flue gas turbulent flow heat exchange method is based on the heat exchange device, and comprises,
cooling and condensing the flue gas in a return process; the smoke discharged from the burner flows through the gaps of the inner and middle layers of coil pipes to absorb radiant heat, the smoke flows through the gaps of the disc pipes and sequentially passes through the inner layer of disc pipes and the middle layer of disc pipes to increase the viscous resistance of the smoke, so that turbulent smoke at the outlet of the burner is converted into laminar flow from turbulent flow, and the absorption of radiant heat and convection heat is mainly performed;
cooling and condensing the flue gas in a second return stroke; after laminar flow flue gas flows through the flat coil pipe gaps to carry out two-pass cooling and condensation on the flue gas, the flue gas flows along the flue gas channel close to the wall surface and is collected and discharged into a smoke outlet.
Preferably, the smoke temperature of the smoke inlet for the return cooling and condensation of the smoke is 950-; the smoke temperature of the smoke inlet for cooling and condensing the smoke in the two return strokes of the smoke is 330 ℃ and 390 ℃, and the smoke temperature of the smoke outlet can be reduced to 30-47 ℃.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention relates to a three-coil gas flue gas turbulent flow heat exchange device, which takes a burner, an inner layer circular coil, a middle layer circular coil and an outer layer flat coil as main bodies, adopts the design of the inner layer, the middle layer and the outer layer of coils, arranges the light pipe coils of the two layers in the middle of the inner layer in a staggered way to form a radiation-sealed hearth, and adopts the flat coil to cool and condense flue gas on the outer layer, thereby effectively improving the heat efficiency of a boiler; when the condensation flue gas is cooled, the viscous resistance of the flue gas is increased, the flowing state of the flue gas is changed from turbulent flow to laminar flow, the heat exchange coefficient is increased, and the cooling and condensation capacity of the flue gas is enhanced. And inlayer circle coil pipe and middle level circle coil pipe staggered arrangement form radiation confined furnace, according to radiation fourth power law, can absorb the radiant heat to the flue gas by a wide margin that is discharged by the combustor, compare the flat coil heat transfer wall of a return journey of present in service, manufacturing process is simpler, and heat transfer coil pipe is compacter, and cost is cheaper.
Furthermore, a water return loop is arranged according to a heat exchange return stroke, an inner-layer disc pipe in the first return stroke is connected with an inner-layer header through a reducing design, and an outer-layer flat coil pipe in the second return stroke is connected with an outer-layer header through a 90-degree elbow; in the return water system, return water firstly enters the outer layer collection tank, enters the inner layer collection tank from the bottom after going in and out from the top, and then flows out of the system from the bottom of the inner layer collection tank to be recycled or used as process water of other units. Reasonable water return system design makes whole device have lower return water resistance, improves the utilization ratio of water resource, effective water economy resource.
The invention relates to a three-coil gas flue gas turbulent flow heat exchange method, which is characterized in that through two return heat exchanges, flue gas radiation heat and convection heat are absorbed in one return, the viscous resistance of the flue gas is increased, the change of a flow state from turbulent flow to laminar flow is realized, the temperature of the flue gas is greatly reduced, a flat coil parallel connection structure with extremely small gap is arranged in the two return, the flue gas is deeply cooled and condensed, the heat exchange coefficient is increased, the cooling and condensing capacity is enhanced, the temperature of the flue gas can be reduced to 30-47 ℃, and the energy conservation and emission reduction are assisted.
Drawings
FIG. 1 is a cross-sectional view of the overall structure of an apparatus according to an embodiment of the present invention.
Fig. 2a is an isometric view of an inner layer disk tube structure according to an example of the invention.
FIG. 2b is a top view of an inner layer disk tube structure according to an embodiment of the present invention.
FIG. 3 is a schematic view of an outer layer flat coil structure according to an embodiment of the invention.
FIG. 4 is a schematic diagram of an inner header structure according to an embodiment of the invention.
FIG. 5 is a schematic diagram of an outer header structure according to an embodiment of the invention.
In the figure: the device comprises an outer-layer header return water inlet 1, an outer-layer header 2, a combustor closed port 3, a combustor 4, a flat coil pipe connector 5, an outer-layer header connector 6, an inner-layer disc pipe connector 7, an inner-layer header inner-layer connector 8, a middle-layer disc pipe connector 9, an inner-layer header middle-layer connector 10, an inner-layer header 11, an outer-layer flat coil pipe 12, a flat coil pipe gap 13, a positioning gasket 14, a near-wall flue gas channel 15, an inner-layer circular coil pipe 16, an inner-layer circular coil pipe reducer pipe orifice 16-1, a middle-layer circular coil pipe 17, an inner-layer coil pipe gap 18, an inner-layer header return water outlet 19, an elbow 20, refractory clay 21, a smoke outlet 22 and a shell.
Detailed Description
The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.
The invention discloses a three-coil gas flue gas turbulent flow heat exchange device, which is compact and efficient three-coil gas boiler equipment adopting an inner layer and an outer layer, wherein light pipe coils of the inner layer and the middle layer are staggered to form a radiation-sealed hearth, and a flat coil is arranged on the outer layer to cool and condense flue gas, so that the heat efficiency of the heat exchange device is effectively improved, and the purposes of saving energy, reducing emission and reducing cost are achieved.
Specifically, as shown in fig. 1, the invention includes an outer-layer header return water inlet 1, an outer-layer header 2, a combustor closed port 3, a combustor 4, a flat coil pipe joint 5, an outer-layer header joint 6, an inner-layer coil pipe joint 7, an inner-layer header inner-layer joint 8, a middle-layer coil pipe joint 9, an inner-layer header middle-layer joint 10, an inner-layer header 11, an outer-layer flat coil pipe 12, a flat coil pipe gap 13, a positioning gasket 14, a near-wall flue gas channel 15, an inner-layer circular coil pipe 16, an inner-layer circular coil pipe reducer orifice 16-1, a middle-layer circular coil pipe 17, an inner-layer middle-layer coil pipe gap 18, an inner-layer header return water outlet 19, an elbow 20, fire clay 21, a smoke exhaust port 22 and a.
The flue gas discharged by the combustor 4 firstly flows through the inner-middle layer coil pipe gaps 18 formed by staggered arrangement of the inner-layer circular coil pipes 16 and the middle-layer circular coil pipes 17, namely the furnace water-cooled wall gaps, and absorbs radiant heat, and the flue gas flows from the furnace water-cooled wall gaps between the diameter directions of the heat exchange pipes, so that the temperature at the flue gas inlet of the outer-layer flat coil pipe 12 is greatly reduced, the turbulent flow flue gas inertia force at the outlet of the combustor is reduced, the viscous resistance is increased, and the transition from turbulent flow to laminar flow of the flowing state is realized; the flat coil pipe clearance 13 of outer flat coil pipe 12 of flowing through afterwards carries out two return strokes cooling condensation flue gases, and cooling condensation ability and coefficient of heat transfer all obtain the reinforcing, and required outer coil pipe number of turns is also littleer with total area, effectively saves the consumptive material. In the preferred embodiment, the burner 4 is a cylindrical fully premixed burner, which is arranged in the center of the outer shell 23, the burner has a diameter of 100mm and a length of about 685mm, and is easy to burn low-calorific-value gas, and the gas is less in incomplete combustion, thereby saving gas resources. The bottom of the furnace body section is provided with a lower cover plate wrapping the fire clay 21, the flue gas flows in the flue gas channel 15 close to the wall surface along the outer wall surface of the outer layer flat coil pipe 12 through the inner layer coil pipe, the middle layer coil pipe and the outer layer coil pipe in sequence and is converged to the reducer section below the fire clay 21, and the reducer section is discharged into the smoke outlet 22.
The three-coil gas flue gas turbulent flow heat exchange device adopts the design of an inner layer, a middle layer and an outer layer of coils, wherein the inner wall surfaces of the inner layer of circular coils 16 and the middle layer of circular coils 17, the upper cover plate and the rear cover plate form a closed hearth to absorb the radiant heat and the convection heat of flue gas, the outer layer of flat coils 12 deeply cools and condenses the flue gas, and the flue gas passes through the three layers of coils in sequence to carry out two-pass heat exchange and flows to a smoke exhaust port 22 along a flue gas channel 15 on the near wall surface of a shell.
As shown in fig. 1, the inner layer circular coil 16 and the middle layer circular coil 17 are two layers of circular coils and are arranged in a staggered manner. The inner layer circular coil pipe 16 and the middle layer circular coil pipe 17 have the same screw pitch, the same pipe diameter and the same wall thickness, and according to the installed capacity and the actual situation, the screw pitch of the coil pipes can be 40 mm-64 mm, the pipe diameter can be 24 mm-44 mm, and the wall thickness can be 1.5 mm-3 mm; the spiral radius of the inner layer circular coil pipe 16 can be 320 mm-580 mm, and the spiral radius of the middle layer circular coil pipe 17 can be 370 mm-650 mm; the inner layer circular coil 16 and the middle layer circular coil 17 form two rows of staggered hearth water-cooled walls with the same transverse pitch and the same screw pitch and the longitudinal pitch smaller than the screw pitch; the inner layer circular coil pipe 16 and the middle layer circular coil pipe 17 respectively adopt a multi-coil parallel structure, and a parallel structure is also adopted between the inner layer circular coil pipe 16 and the middle layer circular coil pipe 17. The diameter of the circular cross section combustor 4 is 60 mm-350 mm, the length is 450 mm-780 mm, low-heat value gas is easy to burn, incomplete combustion of the gas is less, and gas resources are saved. The burner 4 is arranged in the center of the hearth and matched with the inner-layer and middle-layer circular coil pipes to ensure that smoke is uniformly distributed along the circumference, and a contact space of 45 mm-950 mm is reserved between the outer surface of the burner head 4 with the circular cross section and the inner surface of the inner-layer circular coil pipe 16 so as to prevent flame from directly scouring the inner surface of the inner-layer circular coil pipe 16 to cause incomplete combustion to cause carbon deposition and reduce the heat exchange efficiency of the coil pipes.
According to the difference of the power of the heat exchange device, the inner layer circular coil pipe 16, the middle layer circular coil pipe 17 and the outer layer flat coil pipe 12 are respectively provided with 1-40 coil pipe units, the number of the coil pipe turns of each coil pipe unit is 1-50, the upper coil pipe unit and the lower coil pipe unit of the outer layer flat coil pipe 12 are stacked, and positioning gaskets 14, positioning comb teeth or bulge bulges are arranged in gaps among the coil pipe units for positioning.
The outer-layer header backwater inlet 1 is arranged at the upper end of the outer-layer header 2 and is communicated with an outer water inlet header cavity, the outer water outlet header cavity is communicated with an elbow 20 arranged at the lower end of the outer-layer header 2, and the elbow 20 is communicated with an inlet arranged at the lower end of the inner-layer header 11; the inlet of the inner layer header 11 is communicated with the inner water inlet header cavity, the return water outlet 19 of the inner layer header is communicated with the inner water outlet header cavity through a bent pipe passing through the shell 23, and the connecting end of the bent pipe is arranged at the lower end of the inner layer header 11;
the cooling water in the outer layer flat coil pipe 12 is all in-out from top, and the cooling water in the inner layer circular coil pipe 16 and the cooling water in the middle layer circular coil pipe 17 are all in-out from bottom.
The working medium firstly enters the outer-layer header 2 and enters from the upper left corner. Flows downwards along the outer water inlet collecting cavity at the left side of the outer layer collecting box 2, the outer layer collecting box interface 6 is connected with the 90-degree elbow of the outer layer flat coil pipe 12, the working medium is uniformly distributed to all the outer layer flat coil pipe units 12, the working medium absorbs the heat of the flue gas in the outer layer flat coil pipe 12, descends, flows, collects and enters the outer water outlet collecting cavity at the right side of the outer layer collecting box 2, the working medium in the outer water outlet collecting box at the right side descends and flows to the bottom, the working medium can be recycled or used as process water of other units, and a reasonable water return system design ensures that the whole device has lower water return resistance; wherein, the flow velocity of the boiler working medium in the inner layer circular coil 16 is not lower than 0.5m/s, the flow velocity of the middle layer circular coil 17 is not lower than 0.42m/s, and the flow velocity of the outer layer flat coil 12 is not lower than 0.3 m/s.
The invention relates to a three-coil gas flue gas turbulent flow heat exchange method, which adopts the heat exchange device and comprises two return cooling and condensing steps;
cooling and condensing the flue gas in a return process; the flue gas exhausted from the burner 4 firstly flows through the gaps 18 of the inner and middle layers of coil pipes to absorb the radiant heat, the flue gas flows from the gaps of the disc pipes and sequentially passes through the inner layer of circular coil pipes 16 and the middle layer of circular coil pipes 17 to increase the viscous resistance of the flue gas, so that the turbulent flow flue gas at the outlet of the burner is converted into laminar flow from turbulent flow, and the absorption of the radiant heat and the convection heat is mainly performed;
cooling and condensing the flue gas in a second return stroke; after laminar flow flue gas flows through the flat coil pipe gaps 13 to carry out two-pass cooling and condensation, the laminar flow flue gas flows along the flue gas channel 15 close to the wall surface and is collected and discharged into the smoke outlet 22.
Wherein, the smoke temperature of the smoke inlet for the return cooling and condensation of the smoke is 950-; the smoke temperature of the smoke inlet for cooling and condensing the smoke in the two return strokes of the smoke is 330 ℃ and 390 ℃, and the smoke temperature of the smoke outlet can be reduced to 30-47 ℃.
In the preferred embodiment, as shown in fig. 2a and 2b, the diameter of the spiral line where the center of the inner layer disk tube is located is 400mm, the thread pitch is 50mm, the diameter of the tube is 32mm, the wall thickness is 2mm, and 16 circles are total; the diameter of a spiral line where the circle center of the middle-layer disc tube is located is 460mm, the thread pitch is 50mm, the diameter of the tube is 32mm, the wall thickness is 2mm, and 16 circles are total; the inner layer circular coil 16 and the middle layer circular coil 17 form two rows of staggered hearth water-cooled walls with the transverse pitch of 50mm and the longitudinal pitch of 30mm, the radiation heat is absorbed, the flue gas flows from the gap of the pipe diameter, namely the gap 18 of the inner layer coil and the middle layer coil, the flue gas inlet temperature is about 1050 ℃, and the flue gas outlet temperature is 390 ℃. In order to reduce the flow velocity of the water side, the inner layer and the middle layer respectively adopt a 4-pipe-coil parallel structure, the inner layer circular coil 16 and the middle layer circular coil 17 are also connected in parallel, the whole structure is equivalent to an 8-pipe-coil structure, the flow velocity of the water side is 1.7m/s, the flow velocity of the smoke side is 3.52m/s, the heat transfer coefficient is 44.5W, and the resistance is about 20 Pa. The inner layer circular coil pipe 16 is connected with the inner layer header 11, but the transverse pitch of the pipe is only 50mm, the inner layer pipe cannot stretch out, as shown in fig. 2a and fig. 2b, the reducer pipe orifice 16-1 of the inner layer circular coil pipe is designed, the circular pipe of the inner layer circular coil pipe 16 gradually becomes an elliptical pipe when turning outwards at 90 degrees, the circular pipe is a short shaft in the vertical direction, the long shaft is equal to the original diameter, and the circular pipe stretches out from the gap of the diameters of the two circles of the middle layer pipes and is connected with the inner layer header 11.
As shown in fig. 3, in the preferred embodiment, the spiral line where the center of the circle of the outer-layer flat coil 12 is located has a design diameter of 680mm, a thread pitch of 27.3mm, a flat tube gap of 0.8mm, 32 turns in total, and 8 units in total are connected in parallel every 4 turns; the wall thickness of the flat tube is 2.3mm, the total width is 80mm, the height is 26.5mm, and the radius of a fillet is 13 mm; the inlet smoke temperature of the flat coil pipe 12 is 360 ℃, and the smaller flat coil pipe gap 13 is set to be 0.8mm, so that the convection heat transfer coefficient of the two-pass flat coil pipe is greatly increased, and the outlet smoke temperature can be reduced to 47 ℃ after heat exchange is carried out in the flat coil pipe gap 13. Taking 140 ℃ as a boundary, extremely little condensation amount at the temperature of more than 140 ℃, and calculating according to convection heat exchange, wherein the flow velocity of flue gas is 12m/s, and the heat exchange coefficient is 141W; the water vapor begins to condense in large quantity between 140 ℃ and 47 ℃, the flow rate of the flue gas is 6.7m/s, and the average heat exchange coefficient can reach 231W. The outer-layer flat coil pipe 12 is welded with two ends of the coil pipe by adopting 90-degree elbows to form a water inlet and a water outlet with end surfaces in the same plane, and considering that the 90-degree elbows occupy partial space, each coil pipe unit is 3.92 circles, and 0.08 circle is left as an elbow occupied area; the upper coil unit and the lower coil unit are stacked together, and a gap between the coil units is positioned by a positioning gasket 14; as shown in fig. 5, the water in all the flat coil pipes is fed from top to bottom, the openings of the left half part are water inlet openings, and the right half part is a water outlet opening. In the preferred embodiment, the outer flat coil 12 is a volleyban flat coil.
As shown in fig. 1, the inner header 11 is arranged between the outer flat coil pipe 12 and the middle round coil pipe 17, as shown in fig. 4, in the preferred embodiment, the water of the outer flat coil pipe 12 enters the right inner water inlet header cavity of the inner header 11 from the bottom, and is distributed to 8 round coil pipes; the water of 8 round coil pipes flows upwards along the coil pipes and is collected in the left inner water outlet collecting cavity, and flows out of the boiler from the bottom of the left inner water outlet collecting cavity through the inner layer collecting tank backwater outlet 19. The inner layer header 11 is respectively provided with an inner layer interface 8 and a middle layer interface 10, and is connected with the inner layer disc pipe reducer pipe orifice 16-1 through the inner layer interface 8 and is connected with the middle layer disc pipe 17 through the middle layer interface 10. The specific shape of the inner header 11 can be adjusted depending on the process, but the water flow rate does not exceed 2.5 m/s. The inner water inlet collecting cavity and the inner water outlet collecting cavity are formed by separating the inner layer header 11 by a partition plate.
As shown in fig. 1 and 5, the system return water first enters the outer header 2, from the upper left corner. Flows downwards along the outer water inlet collecting cavity at the left side of the outer layer collecting box 2, the interface 6 of the outer layer collecting box is connected with the 90-degree elbow of the outer layer flat coil pipe 12, working media are uniformly distributed to 8 flat coil pipes, the working media absorb smoke heat in the outer layer flat coil pipe 12 and flow downwards to be collected into the outer water outlet collecting cavity at the right side of the outer layer collecting box 2, the working media in the outer water outlet collecting box at the right side flow downwards to the bottom, are connected with the bottom of the right side collecting box of the inner layer collecting box 11 through the elbow 20, are distributed into the inner layer round coil pipe 16 and the inner layer round coil pipe 17 through the inner layer collecting box 11 to absorb smoke radiation heat and convection heat, finally are collected into the inner water outlet collecting cavity at the left side of the inner layer collecting box 11 and flow out of the boiler from the bottom of the inner layer collecting, the device can be recycled or used as process water of other units, and a reasonable backwater system design ensures that the whole device has lower backwater resistance; wherein, the flow velocity of the boiler working medium in the inner layer circular coil 16 is not lower than 0.5m/s, the flow velocity of the middle layer circular coil 17 is not lower than 0.42m/s, and the flow velocity of the outer layer flat coil 12 is not lower than 0.3 m/s. Two ends of the outer layer flat coil pipe 12 are respectively connected with an outer layer header interface 6 on the outer layer header 2 after penetrating through the shell through 90-degree elbows, and an outer water inlet header cavity and an outer water outlet header cavity are formed by separating the outer layer header 2 by a partition plate. The outer-layer flat coil pipe 12 is arranged outside the shell 23, the distance between the outer wall surface of the outer-layer flat coil pipe and the outer wall surface of the shell 23 is 60mm, the diameter of a spiral line where the circle center of the flat coil pipe is located is 680mm, the thread pitch is 27.3mm, the gap of the flat pipe is 0.8mm, 32 circles are formed, each 4 circles are a unit, and 8 units are connected in parallel; the wall thickness of the flat tube is 2.3mm, the total width is 80mm, the height is 26.5mm, and the radius of the fillet is 13 mm.
The outer shell 23 comprises a furnace body section which is arranged in a cylindrical shape and a reducing section which is arranged in an inverted cone shape; a lower cover plate is arranged between the furnace body section and the reducing section, and the lower cover plate is wrapped with refractory mortar 21; the inner layer circular coil pipe 16, the middle layer circular coil pipe 17 and the outer layer flat coil pipe 12 are supported on the lower cover plate and are arranged in the furnace body section; the near-wall surface smoke channel 15 is connected with a smoke discharge port 22 through a reducing section; the upper and lower ends of the inner layer circular coil pipe 16, the middle layer circular coil pipe 17 and the outer layer flat coil pipe 12 are respectively arranged with the upper and lower cover plates in a sealing way; gaps between the upper end and the lower end of each layer of coil pipe and the upper cover plate and the lower cover plate are sealed by filling. Gaps between the inlet and the outlet of each coil pipe also need to be filled so as to avoid forming a flue gas corridor and aggravating the abrasion of the pipe wall. In the preferred embodiment, the diameter of the outer shell 23 is 800mm, the total height of the furnace body is 1000mm, the design power of the boiler is 700kW, and the total weight of the boiler body is about 396Kg, and 316L of material is adopted.
In the device, a boiler body consists of an upper cover plate, a lower cover plate, an inner middle double-layer circular coil pipe, an outer layer flat coil pipe and a shell, wherein the upper cover plate and the lower cover plate are internally coated with refractory materials. The upper cover plate fixes the burner, the circular cross section burner head matches the circular coil pipe to ensure the smoke gas to be evenly distributed along the circumference, the smoke gas flows from the gap of the circular coil pipe, the viscous resistance of the smoke gas is increased, the flowing state of the smoke gas is changed from turbulent flow to laminar flow, thereby the smoke gas is deeply cooled and condensed, and the temperature of the smoke gas at the outlet can be reduced to below 47 ℃. Boiler return water is distributed to all outer layer flat coil pipe units from the outer layer collection tank, is guided into the inner layer collection tank after heat absorption through one return stroke, and is distributed to the inner and middle double-layer circular coil pipes to carry out two return strokes for cooling and condensing flue gas. The three-coil gas flue gas turbulent flow heat exchange device has the advantages of compact structure, low water return resistance and strong cooling and condensing capacity.
Claims (10)
1. A three-coil gas flue gas turbulence heat exchange device is characterized by comprising a shell (23), an inner layer circular coil (16), a middle layer circular coil (17), an outer layer flat coil (12) and a burner (4), wherein the inner layer circular coil, the middle layer circular coil and the outer layer flat coil are coaxially arranged in the shell (23), and the burner (4) is inserted into the upper end of the shell (23) along the axis;
the lower end of the shell (23) is communicated with a smoke outlet (22), the upper end of the shell is provided with an upper cover plate, and the interior of the shell is provided with a lower cover plate; the upper end and the lower end of the inner layer circular coil pipe (16), the middle layer circular coil pipe (17) and the outer layer flat coil pipe (12) are respectively arranged with the upper cover plate and the lower cover plate in a sealing way;
the heat exchange tubes of the inner layer circular coil (16) and the middle layer circular coil (17) are arranged in a staggered manner to form a radiation closed hearth; an inner-middle layer coil pipe gap (18) is formed between the inner layer circular coil pipe (16) and the middle layer circular coil pipe (17); two ends of the inner layer circular coil pipe (16) and the middle layer circular coil pipe (17) are respectively connected with the inner layer header (11);
the inner side of the outer layer flat coil pipe (12) and the middle layer coil pipe (17) are arranged intermittently, the outer side and the inner wall of the shell (23) are arranged in a clearance manner to form a near-wall surface flue gas channel (15), and the adjacent heat exchange pipes are directly provided with flat coil pipe gaps (13); the near-wall surface smoke channel (15) is communicated with the smoke outlet (22); two ends of the outer layer flat coil pipe (12) are respectively connected with the outer layer header (2); the clearance (13) of the flat coil pipes is smaller than the clearance (18) of the inner and middle coil pipes;
an outer-layer header backwater inlet (1) of the outer-layer header (2) is arranged outside the shell (23) and serves as a backwater inlet of the heat exchange device, an outlet of the outer-layer header (2) is connected with an inlet of the inner-layer header (11), and an inner-layer header backwater outlet (19) of the inner-layer header (11) is arranged outside the shell (23) and serves as a backwater outlet of the heat exchange device.
2. The three-coil gas flue gas turbulence heat exchange device according to claim 1, wherein the inner layer circular coil (16) and the middle layer circular coil (17) have the same screw pitch, the same pipe diameter and the same wall thickness; the pitch of the inner layer circular coil pipe (16) and the middle layer circular coil pipe (17) is 40 mm-64 mm, the pipe diameter is 24 mm-44 mm, and the wall thickness is 1.5 mm-3 mm; the helix radius of the inner layer circular coil pipe (16) is 320 mm-580 mm, and the helix radius of the middle layer circular coil pipe (17) is 370 mm-650 mm; the inner layer circular coil (16) and the middle layer circular coil (17) form two rows of staggered hearth water-cooled walls with the same transverse pitch and the longitudinal pitch smaller than the pitch; the inner layer circular coil pipe (16) and the middle layer circular coil pipe (17) respectively adopt a multi-coil parallel structure, and a parallel structure is also adopted between the inner layer circular coil pipe (16) and the middle layer circular coil pipe (17).
3. The three-coil gas flue gas turbulence heat exchange device according to claim 1, characterized in that the cross section of the burner (4) is circular, the diameter is 60 mm-350 mm, and the length is 450 mm-780 mm; a contact space of 45 mm-950 mm is reserved between the outer surface of the combustion head (4) and the inner surface of the inner layer circular coil pipe (16).
4. The turbulent heat exchange device for the three-coil gas flue gas as recited in claim 1, wherein the inner-layer header (11) is arranged between the middle-layer circular coil (17) and the outer-layer flat coil (12); the circular pipes at the two ends of the inner layer circular coil pipe (16) are gradually changed into elliptical pipes when turning outwards at 90 degrees, and extend out from the gap between the two circles of the middle layer circular coil pipes (17) to be connected with the inner layer header (11); two ends of the middle layer round pipe (17) are connected with the inner layer header (11) through 90-degree outward turning.
5. The three-coil gas flue gas turbulence heat exchange device according to claim 1, wherein the outer-layer header (2) is arranged on the outer wall surface of the shell (23), and two ends of the outer-layer flat coil (12) are respectively connected with the outer-layer header (2) through 90-degree elbows; the inner layer circular coil pipe (16), the middle layer circular coil pipe (17) and the outer layer flat coil pipe (12) form a water inlet and a water outlet which are positioned on the same plane.
6. The three-coil gas flue gas turbulence heat exchange device according to claim 1, wherein the outer casing (23) comprises a furnace body section in a cylindrical shape and a reducer section in an inverted cone shape; a lower cover plate is arranged between the furnace body section and the reducing section, and the lower cover plate is wrapped with refractory mortar (21); the inner layer round coil pipe (16), the middle layer round coil pipe (17) and the outer layer flat coil pipe (12) are supported on the lower cover plate and are arranged in the furnace body section; the near-wall surface smoke channel (15) is connected with a smoke outlet (22) through a reducing section.
7. The turbulent heat exchange device for the three-coil gas flue gas as recited in claim 1, wherein 1-40 coil units are respectively arranged on the inner-layer circular coil (16), the middle-layer circular coil (17) and the outer-layer flat coil (12), and the number of coils of each coil unit is 1-50; the upper and lower coil pipe units of outer flat coil pipe (12) stack the setting, and the gap between the coil pipe unit sets up locating pad (14), location broach or bulge and fix a position.
8. The three-coil gas flue gas turbulence heat exchange device according to claim 1, wherein the outer-layer header return water inlet (1) is arranged at the upper end of the outer-layer header (2) and communicated with an outer water inlet header cavity, the outer water outlet header cavity is communicated with an elbow (20) arranged at the lower end of the outer-layer header (2), and the elbow (20) is communicated with an inlet arranged at the lower end of the inner-layer header (11); the inlet of the inner layer header (11) is communicated with the inner water inlet collecting cavity, the return water outlet (19) of the inner layer header is communicated with the inner water outlet collecting cavity through a bent pipe passing through the shell (23), and the connecting end of the bent pipe is arranged at the lower end of the inner layer header (11);
the cooling water in the outer layer flat coil (12) is fed in and discharged out from the top, and the cooling water in the inner layer circular coil (16) and the cooling water in the middle layer circular coil (17) are fed in and discharged out from the bottom.
9. A three-coil gas flue gas turbulent flow heat exchange method is characterized in that a heat exchange device based on any one of claims 1 to 8 comprises,
cooling and condensing the flue gas in a return process; the flue gas discharged from the combustor (4) flows through the gaps (18) of the inner-layer coil pipes and the middle-layer coil pipes to absorb radiant heat, flows through the gaps of the disc pipes and sequentially passes through the inner-layer circular coil pipes (16) and the middle-layer circular coil pipes (17), so that the viscous resistance of the flue gas is increased, the turbulent flow flue gas at the outlet of the combustor is converted into laminar flow from turbulent flow, and the absorption of radiant heat and convection heat is mainly performed;
cooling and condensing the flue gas in a second return stroke; after laminar flow flue gas flows through the flat coil pipe gaps (13) to carry out two-pass cooling and condensation, the laminar flow flue gas flows along the flue gas channel (15) close to the wall surface and is collected and discharged into the smoke outlet (22).
10. The turbulent heat exchange method for three-coil gas flue gas as recited in claim 9, wherein a flue gas inlet flue gas temperature of flue gas condensed by a return cooling is 950-; the smoke temperature of the smoke inlet for cooling and condensing the smoke in the two return strokes of the smoke is 330 ℃ and 390 ℃, and the smoke temperature of the smoke outlet can be reduced to 30-47 ℃.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114110549A (en) * | 2021-11-19 | 2022-03-01 | 西安交通大学 | Gap type mosquito-repellent incense tubular steam boiler |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114110549A (en) * | 2021-11-19 | 2022-03-01 | 西安交通大学 | Gap type mosquito-repellent incense tubular steam boiler |
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