US3580237A - Air heater - Google Patents

Air heater Download PDF

Info

Publication number
US3580237A
US3580237A US796532A US3580237DA US3580237A US 3580237 A US3580237 A US 3580237A US 796532 A US796532 A US 796532A US 3580237D A US3580237D A US 3580237DA US 3580237 A US3580237 A US 3580237A
Authority
US
United States
Prior art keywords
discs
duct
air heater
combustion chamber
air
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US796532A
Other languages
English (en)
Inventor
Alan Barsby
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Marshall Sons and Co Ltd
Original Assignee
Marshall Sons and Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Marshall Sons and Co Ltd filed Critical Marshall Sons and Co Ltd
Application granted granted Critical
Publication of US3580237A publication Critical patent/US3580237A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • F24H3/006—Air heaters using fluid fuel

Definitions

  • This invention relates to an air heater compris- [54] m HEATER ing a combustion chamber, means to supply air and a com- 9 Claims 7 Drawing Figs bustible fuel to the combustion chamber, an exhaust for the products of combustion from the combustion chamber, a first LS- Cl. duct onnecting the combustion hamber to the exhaust an 126/ 1 17, 55/5, 35/7, 165/9, 165/10 inlet and an outlet for air to be heated a second duct intercon- [51] Int.
  • Cl F2411 3/12 acting the inlet and outlet Said second duct Surrounding the [50] Field of Search 165/6, 7, 9, combustion chamber f g f its length and f a diff t 5, 10; 263/20; 126/110, 108 art of its length being parallel to, and sharing a common [561 References CM 12222132? l;l"1fi$?f IZZZZEFJZZEJ; UNITED STATES PATENTS discs extending through said common boundary into both 1,601,355 9/1926 Esbran 165/9 ducts, and means to rotate each disc about its axis of sym- 3,l64,145 1/1965 Tolson 126/110 metry.
  • Thermal regenerators currently in vogue employ a permeable heat transfer member in the form of a drum-shaped rotor containing a suitable heat-transferring material exhibiting a very large surface area to the heated and heating streams.
  • a permeable heat transfer member in the form of a drum-shaped rotor containing a suitable heat-transferring material exhibiting a very large surface area to the heated and heating streams.
  • This invention relates to an improved air heater which utilizes a form of thermal regenerator (generally held to be of outmoded design) which utilizes discs as the heat transfer members, each disc rotating about its axis of symmetry, thus providing an air heater of simple construction which, since the fluid passages in the thermal regenerator need not be narrow, can be operated without danger of the thermal regenerator being blocked by particles (e.g. of soot) swept along by the hot gas stream.
  • a form of thermal regenerator generally held to be of outmoded design
  • discs as the heat transfer members
  • an air heater comprises a combustion chamber, means to supply air and a combustible fuel to the combustion chamber, an exhaust for the products of combustion from the combustionchamber and a first duct connecting the combustion chamber to the exhaust, an inlet and an outlet for air to be heated, a second duct interconnecting the inlet and outlet, said second duct surrounding the combustion chamber for part of its length and for a different part of its length being parallel to, and sharing a common boundary with, said first duct to define a thermal regenerator, the thermal regenerator comprising a plurality of heat transfer discs extending through said common boundary into both ducts and means to rotate each disc about its axis of symmetry.
  • each disc may have the plane of each disc parallel to the direction of gas flow in the ducts (since this facilitates the division of either or both ducts into two or more passes), but an angle of inclination (say up to 30) may assist in generating turbulence in the ductsand result in improved heat transfer rates between the gases and the discs.
  • the first and second ducts are rectangular in cross section and the discs are arranged in sets spaced apart along the ducts, each disc in one set being substantially coplanar with a corresponding disc in the other set or each other set, whereby a baffle may be located in either duct between two discs of one set and, extending in a direction parallel with the plane of one of said discs, pass between the corresponding two discs of every other set.
  • discs are arranged in sets, each set comprising a plurality of parallel discs with their axes of symmetry collinear, the common boundary in the vicinity of each set then being formed by an array of spacers located one between each adjacent pair of discs.
  • the spacers are located to one side of the axes and are urged into frictional contact with the surfaces of the discs to serve as scrapers.
  • the discs and the spacers may be slidably mounted for movement in the axial direction of the drive shaft employed for rotating the discs and are resiliently urged in that direction whereby wear occurring in the discs or spacers is always compensated for.
  • combustion chamber and thermal regenerator lie sideby-side in a common casing with the air inlet adjacent to the combustion chamber, and with the two ducts bent back on themselves through l80 at the same end of the casing.
  • This arrangement leads to a compact self-contained air heater.
  • one or both ducts in the thermal regenerator are adapted to contain baffles to force the gas to flow in a plurality of passes past the discs.
  • these spacers can be adapted to support the baffles.
  • FIG. 1 is a side elevation of a thermal regenerator and an associated furnace which together form the air heater
  • FIG. 2 is an end elevation of the air heater of FIG. I seen from the right
  • FIG. 3 is a section on the line AA of FIG. 2 with a part of the regenerator removed for reasons of clarity,
  • FIG. 4 is an end elevation of part of a set of heat transfer discs used in the regenerator of FIGS. 1 to 3,
  • FIG. 5 is a perspective view of a scraper bar as used in the set of discs shown in FIG. 4,
  • FIG. 6 shows part of a disc guide as employed in the regenerator of FIGS. 1 to 3, and
  • FIG. 7 is a plan from above showing how the disc guides of FIG. 6 are supported.
  • the air heater comprises a furnace (generally designated 1) and a thermal regenerator (generally designated 2).
  • the furnace 1 comprises a combustion chamber 3, into which an oil burner assembly 3a projects, and a fire tube 4 through which the hot gaseous combustion products are conveyed to an end chamber 5.
  • the thermal regenerator 2 comprises an upper duct 6 through which air to be heated is conveyed (i.e. the second duct in the terminology hereinbefore employed) and a lower duct 7 through which the hot gases from the end chamber 5 are led,
  • the two ducts 6 and 7 are both of rectangular cross section and the duct 7 is divided into four passes by partitions 8, 9 and 10, the cross-sectional area of the successive passes getting smaller to compensate for the volume reduction in the combustion gases as the latter cool during passage through the duct 7.
  • the outlet end of the duct 7 leads to an exhaust 12.
  • the air supply for the duct 6 and the combustion chamber 3 is provided by an air blower 11. Part of the air from the blower l I is fed into the chamber 3 while the rest passes along an annular passage 13 surrounding the fire tube 4. The outlet end of the passage I3 terminates in an annular chamber 14 from whence the air is fed to the inlet end of the duct 6.
  • the outlet end of the duct 6 would, in practice, be a connecting pipe which leads the heated air to its point of use (for example a drying chamber).
  • Each set comprises a number of discs 16 mounted in parallel spaced relationship on a shaft 17a, 17b, 170, respectively, the discs being arranged so that each disc in one set is substantially coplanar with a corresponding disc in each of the other two sets.
  • the shafts 17a to lie slightly above the medium plane of a boundary wall 18 (see FIG. 4), which is common to the two ducts 6 and 7, so that slightly over half of each disc is in the upper duct 6 and slightly under half in the lower duct 7.
  • the shafts 17a to 170 are connected to a motor 19 via a gearbox 20, and chain drives 21 and 22 so that the sets of discs are rotated at slow speed (in a typical case at a speed of 2 rpm.) As the discs rotate they are heated by the combustion products in the lower duct 7 and give up heat to the air in the upper duct 6.
  • the boundary wall 18 in the region through which the discs 16 pass is made up of rigid metal scraper bars 23 (e.g. of cast iron), and these are provided with holes 23a by which the bars are supported between the discs 16 on spaced-apart rods 24 (only one of which is shown in FIG. 4).
  • the discs 16 are slidably (but nonrotatably) supported on the shaft 170 and the scraper bars 23 are urged into contact with the discs 23 by springs 25.
  • the scraper bars 23 serve to keep the discs 16 clean and, in particular free from any soot deposits which may form on them while they are in the lower duct 7. Any deposits removed from the faces of the discs by the bars 23 drop into the lower duct 7 from whence they may be periodically removed.
  • the air in the duct 6 must be completely free from any contamination by the products of combustion flowing in the duct 7, this may be achieved by ensuring that the air pressure in the duct 6 is greater than the gas pressure in the duct 7, so that any leakage through the boundary wall 18 will simply result in a small loss of air, and will not cause contamination of the air by the products of combustion.
  • the combustion gas makes four passes along the duct 7 and this, inter alia, compensates for the difference in volume flow between the air and the gas and helps to achieve a more nearly equal flow rate in the two ducts.
  • Some scraper bars may be provided with spaced-apart downwardly extending projections (23b see FIG. 4) between which pass-defining partitions may be slotted. This arrangement has the advantage of ensuring that as the axial length of a set of discs 16 reduces (due to wear of the scraper bars), the partitions remain located between two adjacent discs.
  • the rate of heat transfer between a fluid and a surface in contact therewith is, inter alia, proportional to the relative velocity between the surface and the fluid.
  • the velocity of fluid flow can be increased by utilizing a number of passes (as has already been described) or by reducing the volume of the duct available to the fluid. This reduction in volume can be achieved by placing slabs or blocks in the duct (eg between some of the discs) or by contouring the wall of the duct so that projections, which extend between the discs, are provided.
  • the projections extending between the discs may be employed to stabilize the peripheries of the discs against flexure caused by air pressures or thermal distortions.
  • HO. 6 shows an arcuate disc guide 27 (conveniently designed to extend over at least one-quarter of the circumference of the disc) which can be slidably mounted on bars 28 (see FIG. 7) with intercalated springs 29.
  • the springs 29 ensure appropriate spacing of the peripheries of the discs and the slidable disposition of the guides 27 on the bars 28 allows the guides to approach each other as the axial length of the set of discs reduces due to wear of the scraper bars.
  • discs of metal e.g. copper, mild steel or stainless steel
  • discs of other materials e.g ceramic material
  • the discs may be textured or contoured on their faces to increase turbulence between the disc and the fluid stream (and thus aid heat transfer) provided that the surface can still be kept clean by the abrading action of the scraper bars.
  • the discs can be corrugated in concentric rings coaxial with the axis of the disc. This feature will also increase the rigidity of the disc and increase its surface area.
  • the discs 16 are made of mild steel, are some 2 feet in radius and some l/loinch thick.
  • the temperatures of the gasses in the combustion chamber 3, end chamber and exhaust 12 are some 2,700 F,
  • Air taken in at a temperature of 70 F. has acquired a temperature of F. in the annular space 14 and exits from duct 6 in a hotter stream at 250 F. and a cooler stream at 210 F.
  • the above figures are of course purely exemplary and are not to be considered as imposing limitations on the scope of the invention described.
  • rotational speed of only 2 r.p.m. is employed for the discs in the air heater described, it is important to point out that rotational speeds either smaller, or greatly in excess of this can be used if circumstances make this desirable. For example rotational speeds of a few hundred r.p.m. are contemplated.
  • the rotational speed is normally chosen as the minimum speed that will cause the temperature of any point on the disc to fluctuate only a few degrees (up to, say, 25 F.) during a complete revolution. It will therefore be understood that the temperature of the disc never exceeds very greatly the average temperature of the two fluids, and as a consequence a disc material is required to withstand only this average temperature. However, if such a material is employed, rather than one which could continuously withstand the temperature of the hotter fluid, means should be provided to automatically shut down the oil burner 3a if there is a change in the speed of rotation of the discs 16. Similar provision could be made in the event of failure of the air blower 11.
  • the air heater shown in the drawings is a compact packaged unit which merely requires to be supplied with power for the blower 11 and the motor 19 and fuel for the burner 3a.
  • the composite assembly of furnace l and regenerator 2 are enclosed in a casing 30.
  • baffles in sets so that there is a coplanar relationship between corresponding discs in the three sets enables, as has already been explained, the easy insertion of baffles into both ducts, and this in turn enables the air heater to be operated in a variety of different modes.
  • a plurality of baffles could be used in each duct so that, for example, air in duct 6 makes its initial pass on the left-hand side and exits on the right-hand side while combustion gas in duct 7 makes its initial pass on the right-hand side and exits on the left-hand side.
  • An air heater comprising a combustion chamber; supply means for supplying a combustible fuel to said combustion chamber; exhaust means for exhausting combustion gases from said combustion chamber; first duct means connecting said combustion chamber with said exhaust means; second duct means for air to be heated and comprising one duct section surrounding said combustion chamber and another duct section parallel to and sharing a common boundary with, said first duct means; a plurality of sets of heat transfer discs extending through said common boundary into both of said duct means, said sets of discs being spaced apart lengthwise of said duct means; rotating means for rotating each disc about the axis of symmetry of the same; and baffle means located in at least one of said duct means and extending in substantial parallelism with the plane of at least one of two discs of each of said sets so as to force said combustion gases to flow in multiple passes past said discs.
  • baffle means comprising at least one baffle located in said first duct means.
  • said multiple passes including at least one initial pass and at least one terminal pass each including contact of said gases with different ones of said discs; and further comprising an additional baffle mounted in said other duct section and defining therein two parallel additional passes one of which includes the discs contacted in said initial pass and the other of which includes the discs contacted in said terminal pass.
  • said rotating means comprising a rotary shaft on which said discs are mounted; and further comprising a plurality of spacers constituting said common boundary and being respectively mounted between adjacent ones of said discs slidable axially of said shaft; and biasing means urging said spacers for sliding movement axially of said shaft.

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)
  • Air Supply (AREA)
US796532A 1968-02-08 1969-02-04 Air heater Expired - Lifetime US3580237A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB6194/68A GB1184777A (en) 1968-02-08 1968-02-08 Improved Air Heater

Publications (1)

Publication Number Publication Date
US3580237A true US3580237A (en) 1971-05-25

Family

ID=9810131

Family Applications (1)

Application Number Title Priority Date Filing Date
US796532A Expired - Lifetime US3580237A (en) 1968-02-08 1969-02-04 Air heater

Country Status (4)

Country Link
US (1) US3580237A (en))
BE (1) BE728123A (en))
DE (1) DE1905689A1 (en))
GB (1) GB1184777A (en))

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4557249A (en) * 1985-01-25 1985-12-10 Sundstrand Heat Transfer, Inc. Compact high efficiency furnace
US4718401A (en) * 1986-09-24 1988-01-12 Kenneth J. Dornback, Sr. Hot air furnace
US5368011A (en) * 1993-06-09 1994-11-29 Rheem Manufacturing Company, A Delaware Corp. Appliance combustion chamber
US20050092316A1 (en) * 2003-11-04 2005-05-05 Schonberger Marty L.Sr. Hot air furnace
US20150258515A1 (en) * 2014-03-15 2015-09-17 Anasuya Natarajan DBA GANPADS Apparatus & Process for Airheater without Quench in Carbon Black Production

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB231192A (en) * 1924-03-21 1926-05-06 Alice Sandberg Improvements in regenerative preheaters for air or other media
US1601355A (en) * 1923-10-30 1926-09-28 Firm Tirage Et Ventilation Mec Heat exchanger
GB250172A (en) * 1925-04-03 1927-02-21 Josef Schwab Improvements in regenerator air heaters
FR621430A (fr) * 1925-07-18 1927-05-11 Dispositif applicable aux appareils échangeurs de chaleur pour l'air, le gaz, l'eauou un autre fluide
GB255418A (en) * 1925-07-18 1927-07-29 Alice Sandberg Heat exchanging device for air and other media
US3164145A (en) * 1962-07-09 1965-01-05 American Air Filter Co Air heating apparatus
US3189017A (en) * 1962-02-28 1965-06-15 Thermal Res & Engineering Corp Fuel burning air heating apparatus

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1601355A (en) * 1923-10-30 1926-09-28 Firm Tirage Et Ventilation Mec Heat exchanger
GB231192A (en) * 1924-03-21 1926-05-06 Alice Sandberg Improvements in regenerative preheaters for air or other media
GB250172A (en) * 1925-04-03 1927-02-21 Josef Schwab Improvements in regenerator air heaters
FR621430A (fr) * 1925-07-18 1927-05-11 Dispositif applicable aux appareils échangeurs de chaleur pour l'air, le gaz, l'eauou un autre fluide
GB255418A (en) * 1925-07-18 1927-07-29 Alice Sandberg Heat exchanging device for air and other media
US3189017A (en) * 1962-02-28 1965-06-15 Thermal Res & Engineering Corp Fuel burning air heating apparatus
US3164145A (en) * 1962-07-09 1965-01-05 American Air Filter Co Air heating apparatus

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4557249A (en) * 1985-01-25 1985-12-10 Sundstrand Heat Transfer, Inc. Compact high efficiency furnace
US4718401A (en) * 1986-09-24 1988-01-12 Kenneth J. Dornback, Sr. Hot air furnace
US5368011A (en) * 1993-06-09 1994-11-29 Rheem Manufacturing Company, A Delaware Corp. Appliance combustion chamber
US20050092316A1 (en) * 2003-11-04 2005-05-05 Schonberger Marty L.Sr. Hot air furnace
US6923173B2 (en) 2003-11-04 2005-08-02 Marty L. Schonberger, Sr. Hot air furnace
US20150258515A1 (en) * 2014-03-15 2015-09-17 Anasuya Natarajan DBA GANPADS Apparatus & Process for Airheater without Quench in Carbon Black Production
US9540518B2 (en) * 2014-03-15 2017-01-10 Anasuya Natarajan Apparatus and process for airheater without quench in carbon black production

Also Published As

Publication number Publication date
DE1905689A1 (de) 1969-08-28
BE728123A (en)) 1969-07-16
GB1184777A (en) 1970-03-18

Similar Documents

Publication Publication Date Title
US2023965A (en) Heat transfer
US1746598A (en) Regenerative-heat-transmission apparatus
US2363870A (en) Temperature control of heat transfer surfaces
US3580237A (en) Air heater
US6085829A (en) Regenerator type heat exchanger
US1601355A (en) Heat exchanger
US2795213A (en) Zoned air heater
US2769619A (en) Parallel and counterflow of air in preheater
US2795109A (en) Combined combustion chamber, heat exchanger and flame trap for combustion turbine plants
US1697591A (en) Regenerative air heater
US1823481A (en) Heat exchange device
GB1413473A (en) Regenerative heat exchangers
CA1084607A (en) Fire detector scanning arrangement
US1741225A (en) Heat exchanger
US2795400A (en) Heat transfer elements for rotary regenerative heaters
US2579211A (en) Regenerative heat exchanger
US3229753A (en) Regenerative heat exchangers
US3481392A (en) Tempering duct for rotary regenerative heat exchanger
RU95109663A (ru) Вращающийся регенеративный воздухоподогреватель
RU2123154C1 (ru) Вращающийся регенеративный воздухоподогреватель
US3155152A (en) Rotor structure for rotary regenerative heat exchanger
US3047272A (en) Heat exchanger
US3079991A (en) Rotor construction for rotary regenerative heat exchanger
US1522825A (en) Packing means for regenerative heating devices
US3990503A (en) Regenerative heat exchanger