LIQUID IMMERSION HEATER

Abstract: Liquid immersion heater (10) for heating a body of liquid characterised in that it comprises a combustion chamber (24) arranged, in use, to be located entirely within the body of liquid to be heated, inlet conduit means (36) for feeding combustible gas to the combustion chamber, inlet conduit means (38) for feeding air to the combustion chamber, ignition means (30) associated with the combustion chamber (24) for igniting a combustible mixture in the combustion chamber, said ignition means (30) being arranged to be energised externally of said body of water and a flue conduit (28) passing from the combustion chamber (24) and arranged so that heat from hot gases of combustion pass into the said body of liquid.

Description: TITLE LIQUID IMMERSION HEATER DESCRIPTION The present invention relates to a liquid immersion heater of the type utilising the combustion of fluid fuel. SUMMARY OF THE INVENTION In accordance with one aspect of the present invention there is provided a liquid immersion heater for heating a body of liquid characterised in that it comprises a combustion chamber arranged, in use, to be located entirely within the body of liquid to be heated, inlet conduit means for feeding pressurised combustible gas to the combustion chamber, inlet conduit 15 means for feeding compressed air to the combustion chamber, ignition means associated with the combustion chamber fdr igniting a combustible mixture in the combustion chamber, said ignition means being arranged to be energised externally of said body of water and a flue conduit passing from the combustion chamber and arranged so that heat from hot gases of combustion pass into said body of liquid. Further, the pressure of gas and compressed air fed to the combustion chamber may be regulated so that the amounts of air and gas are arranged to be at desired levels. Thus, the inlet conduits for gas and air each preferably contains a fluid pressure regulator having an active side and a passive side. Further, in order to have the two pressures co-ordinated, inter-regulator conduit means may be provided for applying the regulated fluid pressure from the passive side of one regulator to the active side of the other regulator. Preferably, the regulators are arranged such that the gas pressure is slightly higher than the air pressure. For example, if the operating air pressure is set at βOp.s.i. or 420 pa, then the gas pressure may be approximately 65p.s.i. or 455kpa. If one of the pressures fluctuates the other pressure can be adjusted to maintain the correct mixture for combustion. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described, by way of example, with reference to the accompanying drawings , in which:- FIGURE 1 is a schematic part sectional view of a liquid immersion heater in accordance with one aspect of the present invention; FIGURE 2 is a sectional view of a fluid pressure regulator to be used in the apparatus of the present invention γ. and FIGURE 3 is a schematic part sectional view of a liquid OM WIf immersion heater in accordance with another aspect of the present invention. DESCRIPTION OF THE INVENTION In Figure 1 of the drawings, there is shown a water immersion heater 10 in accordance .with the present invention housed in a closed water tank 12. The tank 12 comprises a water inlet 14, a steam outlet 18, a safety valve 20 and a water level control means 22. The heater 10 further comprises a combustion chamber 24 having a first end connected to a combustible mixture inlet conduit 26 and a second end connected to a flue conduit 28. As can be seen, the flue conduit 28 is elongated and has a spiral section located below normal water level. This is to ensure that combustion products contact the water to the optimum extent. The flue conduit 28 can take many forms but is preferably elongated where it is arranged to be in contact with the body of liquid to ensure that adequate heat transfer takes place. Further, the flue conduit 28 leaves the tank 12 and is open to atmosphere. The combustion chamber 24 is provided with an ignition means 30 such as a sparking plug or a glow wire. As shown, the ignition means 30 can be energised externally of the tank 12 through a tube 32. The combustion chamber 24 also has a flame detector 34 of known type so that the flow of gas can be stopped if there is no flame. Further, the inlet end of the combustion chamber 24 contains a non- return valve 37. Combustible gas is fed to the apparatus along a conduit 36 from a pressurised source of gas while air is fed to the apparatus along a conduit 38 from a pressured source of air. The gas and air supplies are fed O to a mixing chamber 40 in which they are admixed prior to entering the mixture inlet conduit 26. The mixing chamber 40 contains a respective non-return valve 41 on each of the conduits 36 and 38. Each conduit 36 and 38 is provided with a fluid pressure regulator 42 and 44 respectively. A suitable regulator for use in the present invention is the SMC air regulator model AR200. The regulators 42 and 44 are of the general type shown in Figure 2 which comprises a housing 46, an adjustment spindle 48, a locknut 50, a diaphragm 52, and a spring 54 between the spindle and the diaphragm 52. The spindle 48 is threaded and is threadedly engaged with the housing 46. There is an inlet port 56 and an outlet port 58. A pin 53 extends downwardly from the diaphragm 52 to a disc 55 urged upwardly by a small counter spring 57. The disc 55 is arranged to be urged into engagement with a valve seat by the spring 57 when there is no exerted pressure on the diaphragm 52. In this position no gas can pass through the regulator. Fluid passing between the ports 56 and 58 must pass between the valve seat and the disc 55 which path governs the outlet pressure to a desired level. The level of the outlet pressure is controlled by the position of the diaphragm 52 which controls the position of the disc 55 by means of the pin 53. Thus, if the diaphragm is lowered (as seen in Figure 2) by exerted pressure, such as from the spring 54, the governed gas pressure of the outlet port is increased. The regulator shown in Figure 2, is modified by having a port 60 on the side of the diaphragm 52 remote from the ports 56 and 58. As will be described the port 60 is connected by a conduit, in use, to the other regulator so that the regulated fluid pressure of the other regulator is applied to the diaphragm 52 in addition to the pressure of the spring 54. Henceforth, the side of a regulator which has means arranged to act on a diaphragm to open same will be called the active side while the opposite side of a regulator will be called the passive side. As can be seen in Figure 1, a conduit 62 extends from the passive side of the regulator 42 to the active side of the regulator 44 whilst a conduit 64 extends from the passive side of the regulator 44 to the active side of the regulator 42. -- . In use, pressurised air and gas are fed along the conduits 36 and 38 to the mixing chamber 40 where they are admixed to form a combustible mixture. The combustible mixture then passes along the conduit 26 to the combustion chamber 24. The combustible mixture is ignited by the ignition means 30 and burns in the combustion chamber 24 to produce hot gaseous combustion products which may have a tempera¬ ture in excess of 1200°C. The combustion products OMP pass along the flue 28 which is in heat exchange relation with water in the tank 12. Thus, the hot combustion products heat the wall of the flue 28 and this heat is transferred into the body of water. The apparatus shown in Figure 1 is a steam generator and is designed to produce steam. The steam passes out of the tank 12 through the outlet 18. The flue gases pass along the flue 28 to atmosphere after giving.up most, if not all, of their heat content. The inlet gas pressure is desirably slightly higher than the inlet air pressure and this may be readily achieved by threadedly turning in the spindle 48 of the regulator 42 slightly more than the spindle 48 of the regulator 44. Further, because of the conduits 62 and 64 the regulated pressure of each regulator is applied to the diaphragm of the other regulator. Thus, the pressure applied to each diaphragm is a sum of a spring pressure and a vapour pressure. The spring pressure is the same unless the regulator is reset but the vapour pressure is variable. Thus, if there is a fall in air pressure, as can happen, for example, if compressed air supplied from a compressor and the compressor supply is used for another purpose simultaneously, the pressure applied to the diaphragm of the gas regulator 42 is reduced. This reduces the regulated gas pressure by a corresponding amount. Similarly, if there is a drop in gas pressure, there is a reduction on the pressure-applied to the diaphragm of the air regulator 44. Thus, the regulated air pressure is reduced. In practice, a drop in gas or air pressure leads to a drop in the other vapour pressure until the two pressures are in equilibrium again. The same situation applies in reverse with increases of pressure. The result is that the combustible mixture is maintained within required limits for efficient combustion. If desired, either the conduit 62 or 64 could be omitted since if an assured gas or air pressure supply is available then there may be no need to allow for fluctuations in supply pressure. Turning to Figure 3, there is shown a water heating apparatus similar to that shown in Figure 1 and like reference numerals denote like parts. However, the apparatus of Figure 3 is designed to heat a body of water in an open tank and is not a steam generating apparatus. Further, in the apparatus of Figure 3, the tank 12 is separate from the heating apparatus 10. The heating apparatus 10 is produced with float means 70 to enable it to float on the surface of the body of water. The heating apparatus of Figure 3 can be simply inserted into a body of water in a tank 12 and removed when the water is heated to the required temperature. The tube 32 has an ignition means 12 of known type attached to the free end of the tube 32 above water level. This enables the ignition means 30 to be energised at a point externally of the body of water.

Claims: CLAIMS 1. A liquid immersion heater for heating a body of liquid characterised in that it comprises a combustion chamber arranged, in use, to be located entirely within a bod of liquid to be heated, inlet conduit means for feeding pressurised combustible gas to the combustion chamber, inlet conduit means for feeding compressed air to the co:._*ustion chamber, ignition means associated with the combustion chamber for igniting a combustible mixture in the combustion chamber, said ignition means being arranged to be energised externally of said body of water, and a flue conduit passing from the combustion chamber and arranged so that heat from hot gases of combustion pass into said body of liquid. 2. A liquid immersion heater according to Claim 1, characterised in that the gas and air inlet conduits is each provided with a fluid pressure regulator having an active side and a passive side. 3. A liquid immersion heater according to Claim 2 t characterised in that an inter-regulator conduit extends from the passive side of the gas regulator to the active side of the air regulator and/or an inter-regulator conduit extends from the passive side of the air regulator to the active side of the gas regulator. OMPI 4. A liquid immersion heater according to any one of the preceding claims, characterised in that the flue is of elongated form where it is arranged to be in contact with the body of liquid. 5. A liquid immersion heater according to any one of the preceding claims, characterised in that it comprises a closed tank arranged to contain the body of liquid, the combustion chamber and flue being arranged to be immersed in the body of liquid, and said closed tank having an outlet for a flame produced by heating the body of liquid. 6. A liquid immersion heater according to claim 1, characterised in that it further comprises a mixing chamber located externally of the tank, the gas inlet conduit and the air inlet conduit feeding into the mixing chamber and a further conduit leading from the mixing chamber to the combustion chamber through a wall of the tank. 7. A liquid immersion heater according to any one of Claims 1 to 4, characterised in that it comprises a float means enabling it to be inserted into an open body of liquid and the flue being unenclosed so that it is in heat exchange relation with the body of the liquid when the heater is floating thereon. - ~ ^ -rm 8. A liquid immersion heater according to Claim 2, characterised in that the regulators contain diaphragms and mechanical means for applying pressure to the diaphragm. 9. A method of heating a body of liquid, characterised in that it comprises feeding a pressurised combustible gas and compressed air to a combustion chamber located entirely within the body of liquid, to form a combustible mixture in the liquid, igniting the combustible mixture to produce hot gases of combustion, and passing the hot gases of combustion -through an elongated flue in heat transfer relation with the body of liquid so that heat from the hot gasses of combustion pass into the body of liquid. 10. A method according to Claim 9 . characterised in that the air and gas pressures are regulated by fluid pressure regulators. 11. A method according to Claim 10, characterised in that the pressures are so regulated that the gas pressure is usually slightly higher than the air pressure. 12. A method according to Claim 10 and 11, characterised in that the air and gas pressures are co-ordinated so that a fluctuation in one pressure leads to a drop in the other pressure.

Inventors: MUNTZ MICHAEL CORNELIUS, MUNTZ, MICHAEL, CORNELIUS
Applicants: MUNTZ MICHAEL CORNELIUS, MUNTZ, MICHAEL, CORNELIUS
Application year: 1983
Main classification: F24H1
IPC codes: F23C3, F24H1