MXPA99007349A - Multip station heating apparatus - Google Patents

Abstract

A heating apparatus includes at least first and second burners located in a combustion chamber, the burners being separated by a separator to prevent the flow of unburned fuel from an ignited burner to an area adjacent to an extinguished burner. In another aspect of the current invention, the burners are used to heat water in a multi stage heater

Description

MULTI-STAGE HEATING EQUIPMENT BACKGROUND OF THE INVENTION This invention relates in general to heating apparatuses and more specifically to a multi-stage water heater. It is known to provide commercial gaseous and liquid fossil fuel heaters that use multiple burners in a combustion chamber for water heating. The hot water typically circulates through tubes that are also arranged inside the combustion chamber. The burners are of the type that use a premix of air and gas, and one or more fans supply air to an air chamber in communication with the burner orifices. It is desirable to vary or reduce the rate of ignition or combustion of the burners to be able to equal the load imposed on the apparatus. This can be carried out by varying the feed to the burners, closing individual burners, or by means of a combination of modulation and reduction by discrete stages of the ignition charge. The modulation method varies the amount of fuel and / or air supplied to the burners instead of simply closing or opening them. However, modulation usually requires costly regulators and verification equipment to ensure safe and efficient operation. In addition, it would be very expensive to build an apparatus having many individually controlled zones due to the complexity of the controls needed to properly balance the unit for a variable feed construction. The method of closing individual burners in a control zone hinders the balance but in other aspects it is quite economical. An imbalance in the pressure of the combustion chamber can force the combustion products to move from the burners ignited to the areas or areas of the burners turned off and can return to circulate in the area of the burners ignited. The products of incomplete combustion, then, are allowed to escape from the unit, passing the burners off, which is unacceptable from the point of view of environmental emissions. In other words, the pressure zone above the burners extinguished (ie, where there is neither flame nor fuel) is lower than in the area above the ignited burners when a set of burners is not lit. This leads to the movement of the non-consumed combustion products towards the zone of reduced pressure. Similarly, the pressure in the area below the burners turned off may be less than in the areas where the burners are lit. This also induces the movement of the non-consumed products from below the burners off to the zone of reduced pressure.

SUMMARY OF THE INVENTION According to the present invention, a heating apparatus includes at least first and second burners located in a combustion chamber where the burners are separated by a separator that prevents the circulation of unburned fuel from an ignited burner to a burner. area adjacent to a burner off. In another aspect of the present invention, the burners are used to heat water in a multi-stage heater. Another aspect of the present invention provides pre-mix burners insulated by a separation wall projecting upwardly from a floor in a single combustion chamber. A method is also provided for the operation of a heating apparatus to redirect the air flow between the burner sets. The multi-stage heater of the present invention offers advantages over traditional devices by a reduction in the amount of combustion products not fully consumed that are allowed to escape from the combustion chamber. The separator of the present invention prevents the flow of recirculated air and accompanying unconsumed fuel to the burners off and their exit through the gas discharge conduit. Nevertheless, the configuration of the separator is such that it allows cross ignition between sets of burners when multiple sets of burners are in operation. The heater of the present invention also advantageously uses a mechanism to provide a constant supply of fuel to the burners, while allowing a reduction in the volume of the air flow for combustion by reduced stages. Accordingly, the heating efficiency of the heater is maximized, while allowing for better heater regulation using multiple stages of fuel and / or air inlets. The unconsumed air or gas flow patterns produced by the present invention improve the efficiency and economy of modulation heaters and discrete ignition stages. Other advantages and features of the present invention will become apparent from the following description and appended claims, in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic side view showing the preferred embodiment of a multi-stage heater of the current invention; Figure 2 is a side schematic view, taken at 90 ° of Figure 1, showing the preferred embodiment of the multi-stage heater; Figure 3 is a fragmentary perspective view, taken inside the circle 3 of Figure 1, showing a portion of the preferred embodiment of the multi-stage heater; Figure 4 is a perspective view showing portions of the preferred embodiment of the multi-stage heater; Figure 5 is a side enlarged schematic view, similar to Figure 1, showing the preferred embodiment of the multi-stage heater; and Figure 6 is a side schematic view, similar to Figure 5, showing an alternative embodiment of the multi-stage heater of the current invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment of a multi-stage heater 11 of the current invention can be better appreciated by referring to Figures 1-4. The heater 11 provides heating capacity for heating fluids, such as water and the like, in the range of about 150,000 to 750,000 BTU per hour and is intended for use in light industrial, commercial and residential applications. The heater 11 includes a high-gauge 13-gauge galvanized steel casing, a single combustion chamber 15, a heat exchanger 17, a first set of burners 19, a second set of burners 21, and a separator 23. The heat exchanger 17 preferably includes eight parallel and interlaced tubes of copper fins 25 held horizontally between the side walls 27 and 29 of the combustion chamber 15. The tubes 25 operatively transport the water or other liquid from a cast iron head in a single piece 31 having a water inlet 33 and water outlet 35. Tubes 25 are preferably manufactured by Wolverine Tube, Inc. of Alabama, Model No. C12200 FINN 61-0714068. Tubes from other manufacturers can also be -used. An air chamber or distributor 51 is also disposed inside the casing 13 adjacent to the combustion chamber 15. The air chamber 51 and the combustion chamber 15 are separated by a ceramic fiber refractory tile 53 and an access panel to the combustion chamber (shown in Figure 4, but both have been removed from Figure 2). The burners 19 and 21 project into the interior of the combustion chamber 15 in a horizontally elongated and parallel configuration from the air chamber 51. Each burner is bolted to the access panel to the combustion chamber by means of a flange. burner 55. One end of each burner is placed inside the air chamber 51 to operatively receive the air flow provided by a multiple or proportional speed squirrel cage fan 59, and gas from an orifice located at each burner. Air is supplied to the fan 59 by means of an optional inlet conduit 61 in communication with ambient atmospheric air. An electric motor of fractional power and alternating current 63, with an associated capacitor 65, serves to drive the fan 59. An air shutter 95 (see FIG. 3) is positioned between the fan 59 and the air chamber 51. Preferably, a gas distributor 81 supplies natural gas fuel from a regulator 83 and a valve associated with the orifices 57 of the burners 19 and 21. A second valve 77 is provided in the distributor 81, between the first and second burner sets 19 and 21 respectively, to selectively prevent the flow of gas from the second set of burners 21 when ignition or heating is desired at reduced stages. The burners 19 and 21 are of the type for premix and are preferably manufactured by Burner Systems, Inc. of Chattanooga, Tennessee, model no. 213632393-01. However, burners from other manufacturers can also be used. These burners have a hole and slot design along the top of their cylindrical cross-sectional configurations, through which flames are projected when burning fuel. Alternatively, other gaseous or liquid fossil fuels, such as petroleum, propane or the like, can be used. Ceramic 85-tile fiber tiles and ceramic fiber-wall tiles 87 are provided in the combustion chamber 15. The separator 23 is made in a similar fashion from one-inch (2.54 cm) thick ceramic fiber tile and extends generally upwards from floor tiles 85, vertically. The spacer 23 is frictionally held in place between the central edges of the floor tiles 85. The ceramic fiber tiles 23, 53, 85 and 87 are preferably manufactured by Refractory Specialists, Inc. of Sebring, Ohio, USA. of model FG23-101 or FG23-107. While this tile manufacturer and its composition are suitable for refractory temperatures typically found between 1500 and 1600 ° F (816 and 871 ° C), other materials for the separator, such as steel or sheet, as well as alternate manufacturers, may also be used, depending on temperatures and applications. However, ceramic tiles are lighter, stronger and easier to assemble than a metal sheet separator. Also, a discharge conduit 89 is provided to discharge the gas and air mixture consumed into the environment from the combustion chamber 15. A hot surface ignition system (not shown) is also employed in the combustion chamber 15 to ignite burners, but other ignition systems may be used, such as pilot lights or direct spark ignition methods. An air pressure switch 115 closes the ignition control system if it prevents ventilation. The tubes 25 are located approximately four to six inches (10.16 to 15.24 cm) below the top of the combustion chamber 15, while the burners 19 and 21 are arranged approximately six to eight inches (15.24 to 20.32 cm) below of the tubes 25. For diagnostic purposes, a first flexible hose 97 (see Figure 4) is attached to a pressure gauge 99 for measuring the pressure in the air chamber while a second flexible hose 101 is attached to the indicator 99 for measuring the Venturi pressure of the burners. In addition, a hose (not shown) that senses the pressure in the air chamber is attached to the top of the gas regulator 83 (see Figure 1) to maintain a constant pressure in the regulator and a constant supply of gas, fixed by reference measurements of variations in pressure in the bladder due to air puffs, changes in the length of the discharge duct, obstructions in the ducts, and the like; such variations create changes in the pressure inside the air chamber, thus altering the gas supply rate to the burners when the regulator is not fixed by reference measurements. Figures 1, 4 and 5 show the patterns of air flow inside the heater 11 of the present invention. Atmospheric air enters the inlet conduit 61 and is forced into the air chamber 51 by means of the fan 59. The air then flows into each venturi tube of the burners 19 and 21, regardless of whether they are ignited or not. If only one set of burners is in service, as shown, then the fan 59 can operate at a lower speed to reduce the flow of air to the burners 19 and 21. When the second set of burners 21 is not in service, the gas circulates through the distributor 81 and towards only the first set of burners 19, where they are burned inside the combustion chamber 15. The separator 23 serves to keep the unburned fuel inside an area 103 adjacent to the first set of burners 19 until total or predominantly fuel is consumed. Then, the gases of the air and fuel consumed rise to pass over the separator 23 due to the reduced pressure in the area 105 immediately adjacent to the second set of burners 21. The mixed and heated effluent then passes next to the tubes 25. to heat the water contained therein, exiting through the discharge conduit 89 to the outside. The separator 23 promotes a more complete combustion of the natural gas before being discharged from the combustion chamber 15. However, the upper edge 107 of the separator 23 is, ideally, of an altitude equivalent to the horizontal plane 109 disposed between the upper surfaces of the burners 19 and 21; this allows the transverse ignition, that is, the transmission of the flame from the burners lighted 19 to the burners previously turned off 21, when gas is supplied on both sides of the burners for heating to higher stages. An alternative embodiment of the multi-stage heater 11 is shown in Figure 6. As with the preferred embodiment, a plurality of elongated water-carrying tubes 121 is provided inside a combustion chamber 123. Three sets of burners 125, 127 and 129 are also arranged in the combustion chamber 123, perpendicular to the tubes 121. A first separator 131 is vertically mounted between the first and second burner sets 125 and 127, respectively, while a separate second 133 projects vertically between the second and second burners 125 and 127, respectively. and third burner sets 127 and 129, respectively. The separator 131 is shown, this being higher than the plane between the top of the burners, but having one or more openings 135 to allow cross ignition between sets of burners without significantly affecting the air flow patterns induced by the separator . This configuration of spacers can also be employed in the preferred embodiment. This example of the modality provides the proportional ignition in multiple (or three) stages, in which each set of burners can be ignited independently or not, without taking into account the others, improving fuel combustion in the areas immediately above and below of burners lit. As an alternative, it is also contemplated that two or more fans of speeds and multiple stages can be used in any of the modalities. Various embodiments of the heater of the present invention have been set forth; however, it should be appreciated that other variations may be employed. For example, conformations, configurations and alternative quantities of burners or water pipes can be used. Likewise, a separator can be placed, mounted or configured differently to the separator preferably, as long as it performs the same desired function. Although various materials, suppliers and model numbers have been mentioned, a variety of other materials, suppliers and model numbers can be used. It is intended, in accordance with the appended claims, to encompass these and other variations in the disclosed embodiments that fit within the spirit of the current invention.

Claims (25)

1. - A heating apparatus characterized in that it comprises: a combustion chamber substantially enclosed having a discharge conduit; a first burner located inside the combustion chamber; a second burner located inside the combustion chamber; and a separator located between the first and second burners which serves to prevent the flow of unburned fuel from a first area adjacent the first burner to a second area adjacent to the second burner when the first burner is burning fuel and the second burner is not burning gas.

2. - The device according to the claim 1, characterized in that the fuel includes one of a gaseous and liquid fossil fuel.

3. The device according to the claim 2, characterized in that the burners are of the type that use a premix of air and combustible gas.

4. The apparatus according to claim 1, characterized in that it also comprises a floor in the combustion chamber located towards one side of the combustion chamber substantially opposite to the discharge conduit, the separator projecting upwards from the floor and between the first and second burners.

5. The apparatus according to claim 4, characterized in that the separator extends to a height no higher than a horizontal plane defined by the upper surfaces of the burners.

6. The apparatus according to claim 1, characterized in that the separator has at least one opening to allow transverse ignition between the burners, the cross ignition being otherwise obstructed by the separator.

7. The apparatus according to claim 6, characterized in that an upper part of the separator projects to a height higher than the height of the burners.

8. The apparatus according to claim 1, characterized in that it also comprises: an air chamber located adjacent to the combustion chamber; a hole of each of the burners located in the air chamber, and a fan that supplies air to the air chamber, the ventilator supplying a first volume of air to the air chamber if only the first burner is consuming fuel, and the fan supplying a second volume of air greater than the first volume if the first and second burners are consuming fuel.

9. - The apparatus according to claim 8, characterized in that it also comprises: at least third and fourth burners located parallel to the first burner in the first area of the combustion chamber; and at least fifth and sixth burners located parallel to the second burner in the second area of the combustion chamber, the first and second combustion chamber areas being substantially separated by the separator.

10. The device according to the claim 1, characterized in that it also comprises a set of water carrying tubes placed in the combustion chamber substantially between the burners and the discharge conduit, the tubes being elongated in a direction substantially perpendicular to the elongated direction of the burners, the burners serving to heat water by burning fuel, the apparatus being defined as a multi-stage heater.

11. The apparatus according to claim 1, characterized in that the separator consists of a tile of ceramic fiber substantially straight and rectangular.

12. The apparatus according to claim 1, characterized in that it also comprises: a third burner selectively operable to burn fuel when lit, the fuel being selectively prevented from circulating through the third burner even when the first and second burners are consuming fuel; and a second separator located between the second and third burners, the spacers projecting in a substantially vertical and parallel direction between the burners.

13. A liquid heating apparatus for heating a liquid in response to the combustion of air and a liquid or gaseous fossil fuel, characterized in that it comprises: a discharge conduit; a single combustion chamber coupled to the discharge conduit, the combustion chamber having a first internal area, a second internal area, and a floor; a first set of premix air and fuel burners located in the first area of the combustion chamber; a second set of premix air and fuel burners located in the second area of the combustion chamber; and a separator projecting upwards from the floor in a substantially vertical direction between the burner sets.

14. The device according to the claim 13, characterized in that the separator has at least one opening to allow transverse ignition between the sets of burners, the cross ignition being otherwise prevented by the separator.

15. - The apparatus according to claim 14, characterized in that an upper part of the separator projects to a height higher than the burners.

16. The apparatus according to claim 13, characterized in that it also comprises: a heat exchanger, which serves to transport hot water, located between the burner sets and the discharge conduit; the natural gas fluid fuel being defined; an air chamber located adjacent to the combustion chamber; and a fan that supplies air to the air chamber, the burners being in communication with the air chamber.

17. The apparatus according to claim 13, characterized in that the apparatus is a negative suction fan device.

18. The apparatus according to claim 13, characterized in that it also comprises a natural gas pressure regulator that serves to feed the fuel to the burner sets, a device for varying the flow of the fuel through the regulator in response to the Pressure changes in the air chamber.

19. The apparatus according to the claim 13 characterized in that the separator projects at a height no higher than a horizontal plane substantially defined by the upper surfaces of the burner sets to allow cross ignition between the burner sets.

20. A method of operating a liquid heating having a combustion chamber, a first burner and a second burner, characterized in that the method comprises: (a) - selectively supplying a first quantity of fuel to the first burner while supplying a second burner. and less fuel to at least a second burner; (b) - supplying an air flow through at least one of the burners; (c) - burn the air and fuel in the first burner; (d) heating a liquid in response to step (c); and (e) -impressing the flow of unconsumed fuel from a first area of the combustion chamber adjacent the first burner to a second area of the combustion chamber adjacent the second burner. 21.- The method according to the claim 20, characterized in that it also comprises deflecting the flow of air leaving the first burner of the second burner by using a separator located between the first and second burners. 22. The method according to the claim 21, characterized in that it also comprises the ignition of the second burner by means of transverse ignition from the first burner if fuel is also supplied to the second burner. 23. The method according to claim 20, characterized in that it also comprises directing the air through the venturi tubes of the burners by means of a fan located on the outside of the air chamber. 24. The method according to claim 20, characterized in that it also comprises a ventilation system for ventilation of the combustion chamber by means of the ventilation system using negative pressure. 25. The method according to claim 20, characterized in that it also comprises varying the speed of a fan between a first positive volume adjustment and a second positive volume adjustment. EXCERPT OF THE INVENTION A heating apparatus includes at least first and second burners located in a combustion chamber, the burners being separated by a separator to prevent the flow of unburnt fuel from an ignited burner into an area adjacent to an extinguished burner. In another aspect of the current invention, the burners are used to heat water in a multi-stage heater.