Patent Publication Number: US-2010126432-A1

Title: Heat recovery device

Description:
The present invention relates to a heat recovery device, particularly for stacks of boilers. 
     BACKGROUND OF THE INVENTION 
     Currently it is known to heat water both for residential uses and for industrial uses by means of boilers. 
     These devices can be supplied especially with fuels which, by burning, emit combustion gases which are expelled from the flues. 
     In this last case, water heating occurs due to the heat generated by the combustion of the various fuels, which however release into the environment high-temperature combustion gases which are expelled from the flues, altering the surrounding bioclimate. 
     The use of these devices therefore requires energy and economic resources with high level for their operation, with the drawback of releasing into the environment a quantity of hot, high-temperature combustion gases that still have heat energy, which is lost. 
     Another drawback of this known method is that the high-temperature combustion gases disperse into the environment fine particles originating from combustion, which are very harmful to one&#39;s health. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to solve the noted technical problems, eliminating the drawbacks of the cited background art, by providing a heat recovery device that allows reduction of the temperature at which the combustion gases of heating boilers are expelled from the flues, improving the thermal yield of the boilers. 
     Within this aim, an object of the invention is to provide a device that makes it possible to reduce, in heating boilers or other heat generators for heating water, the difference in temperature between the input water from the aqueduct and the desired value in output. 
     Another object is to provide a device that makes it possible to reduce the calories needed to heat the water up to the desired temperature in boilers or other heat generators. 
     Another object of the invention is to allow a reduction of the quantity of fine particles emitted by heating boilers into the surrounding environment. 
     Another object is to obtain a device that is effective, structurally simple, and can be provided at low cost. 
     This aim and these objects, as well as others that will become better apparent hereinafter, are achieved by a heat recovery device, characterized in that it comprises a tubular element, which is interposed between two ends of a stack or flue and is provided internally with at least one removable coil which has a first input connector which is connected to the aqueduct or to a well and a second output connector for sending the heated water toward devices that are adapted to heat it further or to accumulation tanks. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further characteristics and advantages of the invention will become better apparent from the following detailed description of a particular but not exclusive embodiment thereof, illustrated by way of non-limiting example in the accompanying drawings, wherein: 
         FIG. 1  is a sectional view of a device according to the invention, arranged in a vertical position, suitable to allow the viewing of the components inside it and the hydraulic connections in the condition for use in countercurrent; 
         FIG. 2  is a front view of the double-comb locking means; 
         FIG. 3  is a perspective view of the diffuser cone and of its support; 
         FIG. 4  is a plan view of the diffuser cone and of its support; 
         FIG. 5  is a perspective view of of the heat recovery device with the cover uncoupled from the tubular element; 
         FIG. 6  is a partially sectional schematic view of a possible application of the device; 
         FIG. 7  is a schematic view of a possibility of application of the device with a plurality of modules in a cascade arrangement for serving heating boilers; 
         FIG. 8  is a partially sectional schematic view of the device coupled to a tank for accumulating the heated water; 
         FIG. 9  is a partially sectional view of the heat recovery device. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the exemplary embodiments that follow, individual characteristics, given in relation to specific examples, may actually be interchanged with other different characteristics that exist in other exemplary embodiments. 
     Moreover, it is noted that anything found to be already known during the patenting process is understood not to be claimed and to be the subject of a disclaimer. 
     The terms “lower”, “top”, “upper”, “upwardly” and similar, are hereinafter used with reference to the position of the device and other parts as shown in the enclosed figures. 
     With reference to the figures, the reference numeral  1  designates a heat recovery device, which comprises a tubular element  2  which is hollow and cylindrical and is interposed between two ends of a flue  3  or stack. 
     The tubular element  2  is provided internally with at least one coil  4  of tubes which can be extracted and has a first connector  5 , which is connected to the aqueduct or to a well, for the inflow of water; the first connector  5  is arranged proximately to a lower end  6  of the tubular element  2  and conveys, through a first vertical portion  5   a  that lies inside the coil  4 , the water up to the top of the tubular element  2 . 
     The coil of tubes  4  extends until it approximately skims the internal lateral surface of the tubular element  2 , forming a series of circular turns, which are supported by a double-comb locking means  7  composed of two pairs of linear flanges  7   a,    7   b  which are mutually opposite and have a series of seats for positioning and resting portions of tube that constitute the coil  4 . 
     The locking means  7 , shown in  FIG. 2 , is fixed to the tubular element  2  by means of screws  8 , which pass through appropriately provided holes formed in said element and which, once unscrewed, allow the simultaneous extraction of the locking means  7  and of the coil  4  by means of a handle  9  that can be gripped by a user since it is arranged transversely to the upper end of the locking means  7 . 
     Advantageously, the pipes of the coil  4  are of the non-rigid type, and have the particularity of contracting the coil  4  if the pressure of the fluid contained therein decreases. 
     The path of the coil  4  ends in a second output connector  11 , which is arranged at the lower end  6  of the tubular element  2  and enters a first duct  12  for sending the heated water toward accumulation tanks  30  or toward devices that are adapted to heat it further, such as boilers  31  or heat generators. 
     The stream of combustion gases  13  that exit from the boiler  31  are conveyed into the flue  3 , which engages the lower end  6  by means of a frustum-shaped portion that tapers along the vertical axis and ends with a third tubular connector  14 , which has a circular cross-section and a first opening  15 . 
     The stream of combustion gases  13  that enter from the first opening  15  is advantageously conveyed radially in the direction of the coil of tubes  4  by one or more diffuser cones  16 , which preferably are three and are arranged along the central axis of the tubular element  2  in order to facilitate better heat exchange between the stream of the combustion gases  13  and the water that flows within the coil of tubes  4 . 
     The diffuser cones  16 , shown in  FIG. 3 , are fixed to the locking means  7  by anchoring means  17  consisting of two rods  18 , which are mutually connected in an X-shaped arrangement and have, at their ends, suitable holes  19  which act as seats for locking screws. 
     During heat exchange, therefore, the stream of combustion gases  13  is cooled, entailing the appearance of condensation, which is conveniently collected in a condensation recovery means  20  arranged at the lower end  6  in a region that is proximate to the first opening  15 , the condensation recovery means  20  preferably having a concave tray-like shape provided with a drain tube  21 . 
     The condensation that forms is collected by means of the drain tube  21  in a dust recovery tank  22 , which can be inspected and opened for cleaning and is usually arranged below the tubular element  2 . 
     These combustion gases, after passing through the tubular element  2 , exit from an upper end  10 , flowing inside a cover  23 , which is removable and frustum-shaped and ends with a portion that tapers toward the upper part and is provided with a second opening  24 . 
     The cover  23  is detachably engaged with the upper end  10  of the tubular element  2 , for example with a coupling or a threaded closure (not shown in the figures) for allowing easy inspection of the inside of the tubular element  2 . 
       FIG. 3  shows how the heat recovery device is connected to the flue  3 ; in particular, it is shown how the flue  3  is engaged in the first opening  15  and continues after the outlet of the second opening  24 . 
     Thermometers are placed for checking correct operation and efficiency of the heat recovery device: more precisely, there is a first thermometer  25 , which is associated with the first connector  5  for the input of the water that arrives from the aqueduct, a second thermometer  26 , which is associated with the second connector  11  at the exit of the water from the tubular element  2 , a third thermometer  27  for measuring the temperature of the combustion gases that enter the device  1 , which is associated with the third connector  14  of the lower end  6 , and finally a fourth thermometer  28  for measuring the temperature of the combustion gases in output, which is placed on the cover  23 . 
     The present heat recovery device can be simply arranged at the output of a boiler  31  and therefore serves a single residential use, as shown in  FIG. 6 , or inserted in a plurality of modules in a cascade arrangement to serve a plurality of boilers  31 , for example in condominiums as shown in  FIG. 7 . 
     The operation of the device is as follows. 
     The boiler, by starting operation both to heat sanitary water and to heat rooms, burns fuel, thus emitting hot combustion gases which are directed to the flue  3 . 
     The water that arrives from the aqueduct, at ambient temperature, is not routed directly to the boiler  31  but flows first inside the tubular element  2  interposed between two ends of the flue  3  and only then collects in the boiler  31 . 
     When the hot water is demanded by the user, both residential and industrial, for example by opening a tap, the supply water from the aqueduct enters the first connector  5 , where there is a first thermometer which measures its temperature, and subsequently begins to flow within the coil of tubes  4 . 
     The demand for hot water starts the boiler  31 , which emits combustion gases, which enter the flue  3  and pass through the first opening  15 , skimming the coil of tubes  4 . 
     The stream of combustion gases  13  is guided inside the tubular element  2  by the diffuser cones  16 , which add to the stream of combustion gases  13 , which previously was substantially vertical, a radial component, thus creating greater turbulence around the coil of tubes  4 , thus increasing heat exchange. 
     The water, by flowing through the entire coil of tubes  4  in countercurrent, after being conveyed to the top of the tubular element  2  by means of the first connector  5 , acquires heat from the combustion gases which reach the second output connector  11  at the lower end  6  with a higher temperature than that of the water that arrives from the aqueduct. 
     After flowing through the entire device, the water enters the boiler  31 , thus requiring fewer calories for further heating up to the desired temperature. 
     Moreover, the hot combustion gases at the output of the boiler  31  undergo cooling before they are introduced in the environment, leading to a suppression of emitted fine particles. 
     Condensation caused by heat exchange can in fact form inside the tubular element  2  and, by descending in countercurrent with respect to the stream of combustion gases  13 , captures the fine particles, collecting in the condensation recovery means  20 . 
     The generated condensation, which contains the impurities of the combustion of the gases, descends from the condensation recovery means  20  through the drain tube  21  down to the particle recovery tank  22 , which can be inspected and opened for cleaning. 
     During heat exchange, in addition to condensation, impurities can form which can deposit on the outer surface of the coil of tubes  4 , thus reducing heat conductivity between the tubes and the stream of combustion gases  13 . 
     However, these impurities are removed whenever the boiler demands water, for example when the user opens a hot water tap, because the pressure inside the tube decreases and the tube reacts by compressing axially. 
     The axial movement, caused by the contraction of the coil of tubes  4 , upon the variation of the pressure of the fluid inside it, leads to the breakup and fragmentation of the impurities that might form on the pipes, such impurities descending by gravity toward the condensation recovery means  20 . 
     If the user demands only heating of the rooms, the stream of hot combustion gases  13  heats the water that is present inside the coil of tubes  4 , making it available at a higher temperature for subsequent use. 
     One possible arrangement of the heat recovery device can provide for the presence of the accumulation tank  30 , which is arranged so as to receive the water in output from the tubular element  2  before it is conveyed into the boiler  31 . 
     The accumulation tank  30  has a fifth thermometer  38  for measuring the temperature of the water contained therein. 
     In this case, a second duct  29 , which is connected to the second connector  11  for the outflow of the water from the tubular element  2 , is connected to the lower region of the accumulation tank  30 , and a circulation pump  32  is inserted in the second duct  29 . 
     The accumulation tank  30  further has a third delivery duct  33 , which is arranged in the upper region; the third duct  33  continues by splitting into a fourth duct  34  for entering the boiler and a fifth duct  35  which ends with a first redirection valve  36 , which is arranged in the pipe of the aqueduct  37 , which in turn is connected to the first connector  5  of the tubular element  2 . 
     For allowing the formation of a closed circuit between the accumulation tank  30  and the device  1 , there is a second redirection valve  40 , which intercepts the fourth duct  34  and the fifth duct  35 . 
     For the use of sanitary water, operation is as described earlier; the accumulation tank  30  receives water at a higher temperature than the water of the aqueduct if the heating system is in operation. 
     If instead the boiler operates only for room heating, the first redirection valve  36  is activated automatically, preventing the inflow of the water of the aqueduct in the tubular element  2 , and simultaneously the circulation pump  32  is started, allowing the water of the accumulation tank  30  to flow within the tubular element  2 , circulating within the closed circuit formed between the accumulation tank  30  and the device  1 , in turn being heated and being thus ready for any subsequent use. 
     The device can also be inserted horizontally and can thus adapt to any arrangement of the flue  3 . 
     The device that has just been described has a heat exchange in countercurrent, but it is also possible to achieve heat exchange in equicurrent if this is more favorable for operating reasons. 
     This last case requires the swapping of the connections between the intake and the delivery. 
     The device therefore makes it possible to recover the heat of the stream of combustion gases by heating the sanitary water before it enters the boiler, reducing considerably the difference in temperature between the water that arrives from the aqueduct or well and the temperature desired by the user. 
     It has thus been found that the invention has achieved the intended aim and objects, a device having been devised which makes it possible to reduce energy consumption and reduce emissions of fine particles generated by combustion in order to obtain hot water to be used for industrial or civil purposes. 
     Of course, the materials used, as well as the dimensions that constitute the individual components of the invention, may be more pertinent according to specific requirements. 
     The various means for performing certain different functions need not certainly coexist only in the illustrated embodiment but can be present per se in many embodiments, including those that are not illustrated. 
     The characteristics indicated as advantageous, convenient or the like may also be omitted or replaced with equivalents. 
     The disclosures in Italian Patent Application No. TV2008A000151 from which this application claims priority are incorporated herein by reference.