Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F5/00—Dryer section of machines for making continuous webs of paper
  • D21F5/20—Waste heat recovery
• • 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
  • F28D5/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, using the cooling effect of natural or forced evaporation
• • 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
  • F28D7/16—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 arranged in parallel spaced relation
  • F28D7/1615—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 arranged in parallel spaced relation the conduits being inside a casing and extending at an angle to the longitudinal axis of the casing; the conduits crossing the conduit for the other heat exchange medium
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F17/00—Removing ice or water from heat-exchange apparatus
  • F28F17/005—Means for draining condensates from heat exchangers, e.g. from evaporators
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28G—CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS
  • F28G1/00—Non-rotary, e.g. reciprocated, appliances
  • F28G1/16—Non-rotary, e.g. reciprocated, appliances using jets of fluid for removing debris
  • F28G1/166—Non-rotary, e.g. reciprocated, appliances using jets of fluid for removing debris from external surfaces of heat exchange conduits

Definitions

• the present disclosure is related to energy conservation and global sustainability by recycling exhaust heat from a manufacturing operation. More particularly, the present disclosure relates to a heat exchanger suitable for use in the recycling and reclaiming of exhaust heat from the drying section of a papermaking machine and process.
• heat exchangers such as plate heat exchangers and tubular heat exchangers can be used.
• a plate structure forms two systems of ducts perpendicular to one another. A medium that delivers heat flows in one set of ducts and a medium that receives heat flows in the other set of ducts. The heated receiving medium is then further processed for reuse.
• Tubular heat exchangers are generally provided with a supply of steam or water, and the tubes are surrounded by ribs or equivalent so as to increase the heat exchange area.
• the tubes are typically fitted between a plate structure, and water flow in the ducts formed by the plate structure, for example glycol water.
• Another form of heat recovery system provides a heat exchanger where an air flow that is moist, saturated, or near its saturation curve is arranged to be used as the air flow that delivers heat.
• the air flow that delivers heat is arranged to flow inside vertically oriented tubes substantially from a top of each tube toward a bottom of each tube.
• the air flow that receives heat is arranged to flow in a direction substantially horizontally through gaps between the tubes. In this manner, any condensate coming from the moist air flow that delivers heat in the tubes flows downward along the inner walls of the tubes and is collected in a basin positioned within the duct work of the heat exchanger below the bottom of the tubes.
• such a system is severely flawed.
• the present disclosure provides for a heat exchanger.
• the heat exchanger generally comprises a duct and a plurality of substantially parallel tubes, each having an outer wall and arranged in said duct to define gaps therebetween.
• the heat exchanger also comprises first means for directing an air flow through said duct that delivers heat through the gaps and over said outer walls of said tubes and second means for directing an air flow that receives heat through said tubes;.
• FIG. 2 is a plan view of an exemplary but non-limiting heat exchanger suitable for use with the energy recovery process of the present disclosure
• FIG. 3B is another cross- sectional view of the exemplary but non-limiting heat exchanger of FIG. 2 taken at line 3A, 3B - 3A, 3B showing the spray system in operation.
• the exemplary and non-limiting energy recovery process 10 shown can generally receive a waste heat energy stream 12 in the form of steam, hot air exhaust, moisture laden heated air, particle and/or fiber laden heat exhaust, and the like.
• a waste heat energy stream 12 in the form of steam, hot air exhaust, moisture laden heated air, particle and/or fiber laden heat exhaust, and the like.
• any manufacturing process that takes an air stream, supplies heat energy to the stream to accomplish a task and then vents the exhaust is suitable for use with the process and apparatus of the present disclosure.
• Some exemplary manufacturing process utilizing such processes are herein described.
• the radiant heat emitted from a circuit board manufacturing process can be utilized to provide ambient heating to other locations within the manufacturing operation during cool weather seasons.
• the energy recovery process 10 envisions several process steps and non- limiting options suitable for use with the described energy recovery process 10. If the waste heat energy stream 12 is in the form of hot and dry exhaust gas, a step to determine if additional moisture should be added to the waste heat energy stream 12 can be provided. This step is represented in FIG. 1 as 14. In a situation where the waste heat energy is not saturated, and it has been determined that moisture should be added, one selects "yes" on the decision point. Alternatively, if the waste heat energy stream 12 is in the form of steam, then additional saturation may not be required, this can result in the selection of "no" on the decision point.
• waste heat energy stream 12 to be treated be saturated. Without desiring to be bound by theory, it would be readily appreciated by one of skill in the art that saturation of the waste heat energy stream 12 can enable and enhance latent heat transfer. Naturally, it should be understood by one of skill in the art that if a decision is made to not saturate waste heat energy stream 12, the herein described equipment and process is still suitable for use. The use or non-use of a saturated waste heat energy stream 12 should not be considered as limiting the scope of the invention disclosed herein. Furthermore, the terms "saturated waste heat energy stream 12" and "waste heat energy stream 12" are used interchangeably herein without effect on the overall disclosure or the equipment described herein.
• Fresh air 34 (e.g., clean and uncontaminated) to be heated by the saturated or unsaturated waste heat energy stream 12 can be passed through each of the tubes 32 (i.e., internal to tubes 32). Without desiring to be bound by theory, contact of the saturated waste heat energy stream 12 with the external surface of each of the tubes 32 imparts heat energy to each of the tubes 32. This heat energy is then transferred to the cool fresh air 34 passing through the tubes which can then be recycled in to the manufacturing or other production/use stream.
• heat exchanger 16 preferably consists of a series of tubes 32 containing the fresh air 34 passed therethrough that are to be heated by the saturated waste heat energy stream 12.
• the saturated waste heat energy stream 12 flows over the tubes 32 that are to be heated to provide the heat required to heat the fresh air 34 contained within tubes 32.
• the tubes 32 can be fabricated into a complete unibody construction for heat exchanger 16.
• a set of tubes 32 comprising only a portion of the tubes 32 envisioned to provide a complete heat exchanger 16 can be manufactured as an assembly and provided, for example, as a tube bundle 44.
• the tube 32 material selected should preferably have good thermal conductivity for the operation and for the waste heat energy stream 12 to be treated. Because heat is transferred from a hot (outer) side to a cold (inner) side through the tubes 32, one of skill in the art will understand that there is a temperature difference through the width of the tubes 32. Because of the tendency of the tube 32 material to thermally expand differently at various temperatures, thermal stresses may occur during operation. This is in addition to any stress imparted to the tubes 32 from the pressures exerted upon the tubes 32 from the fluids (such as waste heat energy stream 12) themselves.
• the tube 32 material also should be compatible with both the shell and tube 32 side fluids for long periods under the operating conditions (temperatures, pressures, pH, etc.) to minimize deterioration such as corrosion. All of these requirements call for careful selection of strong, thermally-conductive, corrosion-resistant, high quality tube materials, typically metals, including copper alloy, stainless steel, carbon steel, non-ferrous copper alloy, Inconel ® , nickel, Hastelloy ® , titanium, high conductivity coppers, brasses, wrought Martensitic ® stainless steel, aluminum bronzes, 90/10 aluminum bronze, 92/8 aluminum bronze, hard (wrought), 93/7 aluminum bronze, hard (wrought), 95/5 aluminum bronze, 1/2 hard (wrought), 95/5 aluminum bronze, hard (wrought), nickel iron aluminum bronze, as extruded (wrought), combinations thereof, and the like. Further, tubes 32 can be provided in several non-limiting types including plain, longitudinally finned, radially finned, extruded, rolled, seamed, and the like.
• tube 32 length should be considered in order to make the heat exchanger 16 as long as physically possible whilst not exceeding production capabilities. Additionally, one of skill in the art will appreciate that it is practical to ensure that the tube 32 pitch (i.e., the center-center distance of adjoining tubes 32) is not less than 1.25 times the outside diameter of the tube 32. However, one of skill in the art could use any tube pitch desired to provide the desired air flow and transfer necessary to optimize the performance of heat exchanger 16 for the waste heat energy stream 12 used. Further, it should be understood that the use of corrugated tubes 32 can increase the turbulence of the fluids involved. Without desiring to be bound by theory, it is believed that turbulence can increase heat transfer and provide better performance.
• the heat exchanger 16 can be thought of as two fluid streams that are thermally connected (e.g., saturated waste heat energy stream 12 and cool fresh air 34). Let the fluid streams be of equal length, L, with a heat capacity (energy per unit mass per unit change in temperature) and let the mass flow rate of the fluids through the heat exchanger 16 be (mass per unit time), where the subscript i applies to saturated waste heat energy stream 12 and cool fresh air 34.
• the temperature profiles for the fluid streams can be represented as T ⁇ x) and T 2 (x) where x is the distance in the tube.
• T ⁇ x the temperature profiles for the fluid streams
• T 2 (x) the temperature profiles for the fluid streams
• clean water can be provided for input into the initial stages of the papermaking process, such as the pulper as well as other systems associated with the preparation of pulp for the production of paper products.
• clean recycled water can be provided for input into a steam generation system used to generate the steam necessary for the various drying stages of the papermaking process.
• this heated water can be filtered and input into a potable or unpotable water supply stream.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=48468764

Family Applications (1)

Country Status (5)

Families Citing this family (1)

Family Cites Families (22)

• 2012
  • 2012-04-30 US US13/459,355 patent/US20130284402A1/en not_active Abandoned
• 2013
  • 2013-04-25 CA CA2872276A patent/CA2872276A1/en not_active Abandoned
  • 2013-04-25 MX MX2014011533A patent/MX2014011533A/es unknown
  • 2013-04-25 EP EP13724047.9A patent/EP2844946A1/en not_active Withdrawn
  • 2013-04-25 WO PCT/US2013/038095 patent/WO2013165787A1/en active Application Filing

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events