Abstract:
A biomass fired boiler having a series of inverted U-shaped exhaust gas flues. Water from a collection tank is pumped and sprayed onto deflection plates in the towers. The exhaust gases progressively commingle with the droplets to extract heat energy and collect contaminants at the tank until all the smoke has been absorbed into the water. The heated water is re-directed through a thermal exchanger of the heat transfer system and heat energy is reclaimed. Floating and/or suspended contaminants are filtered and/or collected and appropriately removed and/or incinerated.

Description:
RELATED APPLICATION DATA 
       [0001]    This is a non-provisional application of provisional application Ser. No. 60/923,823, filed Apr. 17, 2008. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to biomass fired boilers and, in particular, to a high-efficiency boiler that can be fired with a variety of alternative combustible fuels (e.g. wood, coal, waste, byproducts, pellets, corn, petroleum waste, gas, oil or other organic material) and wherein the exhaust gases are conducted through a shower system to absorb the exhaust gases (i.e. smoke), reclaim the exhausted heat and clean contaminants from the gaseous effluent. 
         [0003]    The present invention was developed to provide a heating system wherein exhaust gases from a boiler/stove/furnace are passed through a moist environment created by a shower system to absorb the exhaust gases (i.e. smoke), reclaim the exhausted heat and clean carbon dioxide and other contaminants from the gaseous effluent. The shower system comprises a serpentine series of gravity towers (e.g. inverted U-shaped) that channel the exhaust gases; expose the gases to a moisture rich environment (e.g. water droplets and mist); and collect the heated water in a collection tank. The exhaust gases are passed through a humid environment of patterned water droplets and mist that is formed in the towers to absorb the exhaust gases, heat energy and contaminants. The heated water is gravity collected at the collection tank and successively reduced concentrations of exhaust gases are passed to each successive tower. A portion of the heated water is re-circulated through the towers. The remainder of the heated water is filtered, cleaned of effluents and circulated through the liquid heat transfer system associated with the boiler/stove/furnace and/or a secondary thermal transfer system. Solid effluents and contaminants are skimmed, filtered and/or collected, incinerated or otherwise disposed. 
       SUMMARY OF THE INVENTION 
       [0004]    It is a primary object of the invention to provide a high efficiency fuel fired heating system. 
         [0005]    It is further object of the invention to provide a boiler system wherein exhaust gases are conveyed through a shower system comprised of a serpentine series of conduits (e.g. towers) fed with gravity water showers. 
         [0006]    It is further object of the invention to provide a series of inverted U-shaped towers that communicate with a liquid (e.g. water) supply and collection tank. 
         [0007]    It is further object of the invention to provide a system wherein each inverted U-shaped tower includes a spray forming assembly such as a deflector to form droplets and mist that absorb and cleanse the exhaust gases. 
         [0008]    It is further object of the invention to provide a closed system wherein pumps, valves, filters, skimmers, sensors and electro-mechanical servos operate to control and direct water flow from the collection tank to the spray towers and thermal transfer assembly(s); monitor water temperature, water level and collected effluent and contaminants; and channel the gases through each tower until the gases are fully absorbed and solid effluents and contaminants are collected, burned or otherwise disposed. 
         [0009]    The foregoing objects, advantages and distinctions of the invention are obtained in one construction of a biomass fired boiler and associated liquid heat exchange system. Combustion exhaust gases or smoke formed in the burn chamber(s) of the boiler are coupled via a primary flue to a closed system defined by a sequential series of inverted U-shaped towers disposed above a water collection tank. Water from the collection tank is pumped and sprayed onto deflection plates in the towers. The exhaust gases commingle with the droplets and mist to heat the water and extract heat energy, effluents and contaminants contained in the smoke. 
         [0010]    Residual gases are successively channeled from the collection the tank to each tower until fully washed and only vapor remains. A portion of the heated water is re-circulated through the towers. The remainder of the heated water is filtered and circulated through the heat exchanger and thermal transfer system coupled to the boiler and heat energy is reclaimed. Floating and/or suspended contaminants are filtered, skimmed and/or collected and appropriately removed and/or incinerated. Thermal transfer coils may also be included to extract heat at the collection tank. 
         [0011]    In an alternative system construction, the exhaust gases might be conducted through the water at the collection tank (e.g. in the fashion of bubbling) prior to being conducted to the next adjacent tower. 
         [0012]    Still other objects, advantages, distinctions, constructions and combinations of individual features of the invention will become more apparent from the following description with respect to the appended drawings. Similar components and assemblies are referred to in the various drawings with similar alphanumeric reference characters. The description to each combination should therefore not be literally construed in limitation of the invention. Rather, the invention should be interpreted within the broad scope of the further appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  shows a system block diagram to the construction of the smokeless furnace or heat transfer system and wherein the spray towers are shown in partial cutaway to expose internal assemblies. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0014]    With attention to  FIG. 1 , a system diagram is shown to the present novel and inventive heating system  2 . The system  2  includes a boiler/furnace  4  that can be fired with a variety of combustible fuels (e.g. wood, coal, oil, gas, byproducts and other organic/biomass materials). The fuel is burned in an associated burn chamber(s) and heat energy is released and absorbed into a liquid heat transfer media (e.g. water, water/glycol mixture etc.) circulated through an associated closed loop, heat exchanger system  4 . The heat exchanger  4  is located in close thermal transfer proximity to the burn chamber(s) and most typically surrounds all or a portion of the burn chamber(s). The combustion heat is transferred to the liquid media and the media is circulated from the internal or external heat exchanger  4  to a conduit/radiator system  5  that directs the liquid about the heated premises. 
         [0015]    The heat exchanger  4  can include internal exhaust conduits (not shown) that channel the smoke within or about the burn chamber to an associated chimney or flue  6 . The conduits can be located in the burn chamber or in the heat exchanger  4  but are positioned such that the liquid thermal transfer media is in thermal contact with the conduits to most efficiently extract heat contained in the exhaust gases. 
         [0016]    Whereas conventional boilers release a portion of the heat energy to the environment with the smoke or exhaust gases, the present improved heating system  2  directs substantially no smoke or exhaust gases to the environment. Essentially all the exhaust gases and any heat energy in the exhaust gases is captured and any contaminants contained in the effluents are collected and safely processed to prevent a negative impact on the environment. 
         [0017]    The exhaust gases are particularly exposed to a liquid shower or wash system  8  where the exhaust gases are absorbed into a liquid media and the heat is reclaimed and any contaminants are collected. The reclaimed heat trapped in the spray water is combined and re-circulated with the liquid media of the thermal transfer exchanger  4 . 
         [0018]    Turning attention to the upper regions of the boiler  2 , exhaust gases are conducted from the flue  6  to the shower system or washing assembly  8 . The gases can enter the flue  6  at temperatures approaching 900° F. The assembly  8  provides a number towers  10  of appropriate length, height, and cross-sectional shape and diameter to treat the exhaust gases until completely absorbed. Two inverted U-shaped, cylindrical towers  10  are presently provided. The towers  10  project from a cover or canopy assembly  12  of a lower lying liquid holding tank  14 . More or less towers  10  can be adapted to accommodate any particular system. The towers  10  can be constructed to a variety of shapes and orientations, although a gravity supported construction for reclamation of the water is preferred. 
         [0019]    A supply of liquid  16  (e.g. water) is contained in the tank  14  to a level that permits the exhaust gases to flow above the water  16  from one tower  10  to the next. The towers  10  can be constructed to alternative shapes and can be arranged as desired to appropriately direct the liquid  16  and gases into the tank  12  and between the towers  10 . The exhaust gases are conducted between and through the towers  10  due to normal thermal and pressure differentials and/or provided baffles (not shown) and/or fans (not shown) fitted to the towers  10  or tank  12 . 
         [0020]    The water or other appropriate liquid  16  stored in the tank  14  is directed via one or more pumps  18  and a conduit system  20  into the towers  10 . Valves  22  located along the piping of the conduit system  20  control the flow of liquid into the towers  10 . 
         [0021]    A portion of the liquid  16  is sprayed to impinge or strike baffles  24  fitted inside the towers  10 . The baffles  24  break up liquid spray into droplets and mist that fall back through the towers  10  to the tank  14 . The baffles  24  can be positioned at any desired deflection angle, can be constructed of a variety of materials that withstand the environment, and can exhibit a variety of shapes and surfaces defined to produce the most advantageous spray patterns for optimal smoke absorption. The baffles  24  can be solid or porous and can exhibit any geometric shape that facilitates the formation of the desired droplets and mist. The baffles  24  are normally located near the tops of the towers  10 , although can be located anywhere along each tower  10 . Multiple baffles  24  can also be located in each tower  10 . 
         [0022]    Exhaust gases in the towers  10  mix with the droplets and mist to heat the liquid spray and extract heat, particulates and other contaminants emitted with the gases. For flue gases approaching 900° F., the liquid  16  in a nominal 70 cubic foot tank  14  can be elevated to 160° F. As the smoke is absorbed, the droplets and mist fall under the influence of gravity back into the tank  12 . Any solid materials vented from the flue in the smoke (e.g. ash, soot, heavy metals) are held in the tank  14  and typically collect at the top of the liquid  16 , settle to the bottom or are suspended as particulates. 
         [0023]    The liquid  16  is maintained in the tank to a level that forms a space  26  between the top of the liquid  16  and the cover or canopy assembly  12 . The channel space  26  can be in the range of 8 to 18 inches. The channel space  26  allows the exhaust gases to flow from the boiler  2  and sequentially into each of the towers  10 . As noted at  FIG. 1  the gases are depicted to be denser (i.e. darker) nearer the boiler  4  and progressively less dense as each tower  10  is traversed, until only water or steam is emitted from the exit port  28  of the rightmost tower  10 . 
         [0024]    The cover or canopy  12  can be constructed of plastic, stainless steel or other suitable materials or composites resistant to the working environment. Suitable conduits, baffles or fans can also be provided in the space  26  to direct the gases between the towers  10 . Conduits might also be provided in the space  26  to direct a portion of the exhaust gases directly into the liquid  16  in the tank  14  in the fashion of a bubbler to facilitate the extraction of heat and contaminants. 
         [0025]    The leftmost tower  10  also includes a bracket  28  that supports the tower  10  and weight of the intersecting flue piece  6 . A funnel piece  30  mounted to the bottom of the leftmost riser portion of the tower captures the falling water and prevents a downward draft and flow of exhaust gases into the tank  14  rather that up and into the series of towers  10 . 
         [0026]    Distributed about the liquid containment tank  14  are a number of sensors or electrodes. A sensor  32  (e.g. a float) monitors liquid depth. Another sensor  34  monitors liquid temperature. Another servo  36  (e.g. solenoid valve) cooperates with the sensor  32  to admit additional liquid  16  into the tank  14 . Yet another servo  38  can cooperate with the sensor  34  to circulate the heated liquid  16  into the heat exchanger  4  and conduit/radiator system  5 . 
         [0027]    The heat extracted from the exhaust gases and stored in the liquid  16  is returned to the heat exchanger  4  via the conduit system  20  and/or to the external thermal transfer conduit/radiator system  5 . The liquid  16  is normally separately treated for acidity and other chemical changes. Also added to the liquid  16  to soften the water and enhance smoke collection is a mixture of soda (e.g. Sal soda) and a sudsing agent (e.g. tide soap). 
         [0028]    A separate heat exchange coil  7  coupled for example to a domestic hot water system might also be mounted in the tank  14  to heat the domestic water. Supply and return air ducts or conduits  9  and  11  of a heating, ventilating and air conditioning system at the premises (HVAC) might also be fitted to the cover  12  to humidify a supply of air passed through the tank  14  in the space  26  adjacent a smoke free portion of the space  26  and returned to the heated premises. 
         [0029]    As mentioned, effluents frequently collect on the surface of the liquid  16  in the form of a floating moss or agglutination of contaminants. These flotsam materials are skimmed off the liquid  16  with rotating paddles assemblies  40  and  42 . The assemblies  40  and  42  presently each provide several laterally displaced paddle arms or any desired shape that project from an axle that is rotated to cause the paddles to direct the surface effluent to a collection point or chute. The effluent may also collect as suspended particulates in the liquid  16 . Rake tines, an auger, strainer or a variety of other assemblies may alternatively or in combination with each other be used to periodically draw the solid effluents from the liquid  16 . 
         [0030]    The collected materials can be dried and then conveyed to a separate incinerator or back to the burn chamber at the boiler  4  to be re-burned. Alternatively, the materials can be disposed of through other suitable means or mechanisms. 
         [0031]    Also provided at the tank  14  is a filtration assembly  44  that can take a variety of forms. Appropriate filter media and supports can be appropriately located about the tank  14 . The filtration assembly  44  can be selected to filter any desired contaminant, soot, heavy metal, or any other chemical or particulate found in the spray liquid  16 . 
         [0032]    A system controller  50  (e.g. microprocessor based) can be coupled with suitable conductors or wirelessly to monitor the foregoing liquid level and temperature sensors  32  and  34 , filter assembly(s)  44  and collected effluents. The controller  50  can direct the servos  36  and  38 , as well as monitor water clarity, surface debris and direct any associated filtration assembly  44  or the skimmer assemblies  40  and  42  and/or any collector or incinerator assembly that might be provided to collect, remove or incinerate collected contaminants or effluents. Alternatively, a conveyor (e.g. auger based) can be provided to direct the collected debris back into the burn chamber of the furnace  2 . 
         [0033]    While the invention is shown and described with respect to a presently preferred assembly and several considered improvements, modifications and/or alternatives thereto, still other assemblies and arrangements may be suggested to those skilled in the art. It is to be appreciated therefore that the features of the disclosed heating system can be arranged in different combinations. For example, the towers can be serially coupled or coupled in parallel to the collection tank. Contaminant filters and/or a rake or skimmer assembly can be fitted to the tank to extract suspended contaminants. The primary thermal transfer assembly or a separate assembly (e.g. radiator) can be coupled to the tank. The foregoing description should therefore be construed to include all those embodiments within the spirit and scope of the following claims.