GB1599657A

GB1599657A - Hot water boilers

Info

Publication number: GB1599657A
Application number: GB3828477A
Authority: GB
Original assignee: TUBEGUARD BOILERS Ltd
Current assignee: TUBEGUARD BOILERS Ltd
Priority date: 1978-05-26
Filing date: 1978-05-26
Publication date: 1981-10-07

Description

(54) HOT WATER BOILERS (71) We, TUBEGUARD BOILERS LIM ITED, a British Company, of 223 India Buildings, Water Street, Liverpool 2, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to hot water boilers of the type comprising a boiler burner and heat exchanger unit having an outer wateraccommodating shell within which is disposed a fire-box from which fire-tubes extend upwardly through the shell to a so-called smoke-box.

Corrosion of the fire-tubes and/or the firebox is a particular problem at low water temperatures, such as on heat-up, due to condensation therein especially as such boilers generally are associated with a forced water-circulation pump. It is an object of this invention to reduce the tendency for condensation to occur.

Accordingly this invention provides a hot water boiler and heat exchanger unit having an outer water-accommodating shell within which is disposed a fire-box from which a nest of fire-tubes extends upwardly through the shell to a smoke-box, wherein a water shield fitted about the nest of fire-tubes has a lower edge or edges spaced above an upper part of the fire-box so as to control entry of water to the interior of the water shield.

Preferred features of the hot water boiler burner and heat exchange unit of the present invention are: (a) that flow into the water shield about the nest of fire tubes is, in operation, exclusively past that lower edge or edges; (b) that the upper edge of the water shield is terminated close to but below the upper ends of the fire-tubes, preferably attached to a carrier plate therefor: and (c) that a further water shield is mounted over, preferably closely spaced relative to, at least the upper side part of the fire-box, thereby restricting the amount of water traversing the exterior of the fire-box.

Preferably, a said fire-box water shield extends upwardly to a significant extent above the lower edge, or other water access position, of the fire-tube water shield, thereby further restricting water flow over the upper part of the fire-box and into the interior of the fire-tube water shield. In one embodiment, it has been found particularly convenient for the fire-tube water shield to be spaced inwardly of the exterior dimension of the fire-box and for the fire-box water shield to extend wholly substantially parallel with the sides of the fire-box.

Welding or otherwise securing the firetube water shield to an upper carrier plate for the fire-tubes so as to depend therefrom is a particularly convenient way of ensuring accurate location, with water access past its lower edge above the fire-box and without requiring aperturing thereof as would be the case were that shield to be secured to the upper part of the fire-box itself. Then, upper apertures in that water shield are conveniently provided with outwardly directed tubes registering with flow tappings or apertures through the outer shell, or even taken directly through the outer shell for high heating loads. Also, or even alternatively, weir notches at the upper edge of the shield will facilitate both air expulsion and the required water circulation.

Location and spacing of said fire-box water shield is readily achieved by way of discrete spacers at or near a lower edge thereof and locating and spacingxbrackets at an upper intermediate part to rest on the upper edge of the fire-box itself.

One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a section through a boiler burner and heat exhanger unit; Figure 2 is an outline view at right angles to the section of Figure 1; and Figure 3 is a plan view of the boiler of Figures 1 and 2.

In the drawings, the boiler burner and heat exchanger unit 10 is housed within a cylindrical exterior casing 12 separated by a layer of insulation 14, typically of glass fibre, from an outer shell 16 of the unit. The unit 10 comprises a fire-box 18 specifically indicated as being of oil-fired or gas-fired type with a burner entry 20 and pressure relief or inspection passage 22 through a door 24 in a firebox throat 26. A nest of fire-tubes 28. each including helical baffles 30, extends from a lower fire-tube carrier plate 31 on or constituting an upper cover of the fire-box to and through an upper fire-tube carrier plate 32 edge-welded or otherwise secured to the interior of the outer shell 16. The fire-tubes extend into a smoke-box 33 of a readily adjustable turret type exhaust take-off fitting to which our co-pending patent application no. 38285/77 refers.Serial no 1599658 Welded or otherwise secured to and depending from the upper fire-tube carrier plate 32 is a cylindrical water shield 34 surrounding the nest of fire-tubes and extending downwardly to a lower edge 36 spaced by a predetermined desired amount from the top side of the fire-box. As shown, the width or diameter of the water shield 34 is significantly less than that of the fire-box itself to a desired or convenient extent. The fire-box 18 has about its upper part a cylindrical water shield 40 at a relatively close predetermined spacing therefrom and extending upwardly above the fire-box and above the lower edge 36 of the fire-tube water shield 34.The spacing of the shield 40 relative to the fire-box is determined by discrete spacers 42 at or near its lower edge and discrete bracket-like spacers and mounts 44 engaging the upper edge of the fire-box or lower fire-tube carrier plate.

The above-mentioned predetermined desired spacings and shield overlap serve to set the amount of water passing over the fire-box exterior and into and past the fire-tube water shield 34 for release via weir notches 45 at its upper edge serving also for air expulsion on boiler filling and also via upper apertures 46 in the water shield 34 and through tubes 48 to apertures 50 of tappings for boiler flow in the outer shell. Water return or supply tappings 51 for the boiler are shown at a lower part thereof below the side level of the concave base 52 of the fire-box.The allowed water flow is adequate to permit sufficient natural and/or forced water circulation to provide a safe quantity of water within those shields and yet limit that quantity at low water temperatures to ensure a minimum of condensation within the fire-tubes and firebox of sulphurous products of combustion normally largely responsible for corrosion.

It is convenient to provide a boiler temperature limiting thermostat mount through tapping 54 in the lower and overlapped part of the fire-tube water shield 34. A direct outlet 55 may be provided from the water shield itself for high heating loads irrespective of overall boilder water temperature, say to a primary feed for indirect hot water cylinders or calorifier. Then. it is also convenient to provide a primary water flow control thermostat mount through tapping 56 in the outer shell and into the water shield 34, such control being via a pump or valve.

The fact that the water shield 34 depends from the underside of the upper carrier plate 32 with the fire-tubes 28 extending through the latter means that there is a minimum of water backed surface at and adjacent to the smoke-box 34 so as to limit condensation therein which might otherwise find its way into the fire-tubes.

The unit conveniently rest on feet 58. Air bleed valve or water vent tappings may be provided through the upper fire-tube carrier plate as desired, and a boiler drain connection is indicated at 60, which will be at a lower position on the outer shell 16.

WHAT WE CLAIM IS: 1. A hot water boiler and heat exchanger unit having an outer water-accommodating shell within which is disposed a fire-box from which a nest of fire-tubes extends upwardly through the shell to a smoke-box, wherein a water shield fitted about the nest of fire-tubes has a lower edge or edges spaced above an upper part of the fire-box so as to control entry of water to the interior of the water shield.

2. A unit according to claim 1, wherein water flow into the water shield about the nest of fire-tubes is. in operation, exclusively past said lower edge or edges.

3. A unit according to claim 2, wherein water flow from the water shield is via an upper aperture or apertures.

4. A unit according to claim 3, wherein said upper apertures have an outwardly directed tube or tubes registering with a flow tapping or tappings or apertures in the outer shell.

5. A unit according to claim 4, wherein said outwardly directed tubes or at least one of them itself or themselves extend directly through the outer shell.

6. A unit according to any preceding claims, wherein the water shield terminates in an upper edge or edges that is or are close to but below upper ends of the fire-tubes.

7. A unit according to claim 6, wherein the upper edge or edges of the water shield is or are secured to an upper carrier plate for the fire-tubes.

8. A unit according to claim 7, wherein the water shield has weir notches through its sides at its securement to the upper carrier plate.

9. A unit according to any preceding claim, comprising a further water-shield mounted about at least an upper part of the fire-box to control the amount of water that will traverse the exterior of the fire-box.

10. A unit according to claim 9, wherein

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. comprises a fire-box 18 specifically indicated as being of oil-fired or gas-fired type with a burner entry 20 and pressure relief or inspection passage 22 through a door 24 in a firebox throat 26. A nest of fire-tubes 28. each including helical baffles 30, extends from a lower fire-tube carrier plate 31 on or constituting an upper cover of the fire-box to and through an upper fire-tube carrier plate 32 edge-welded or otherwise secured to the interior of the outer shell 16. The fire-tubes extend into a smoke-box 33 of a readily adjustable turret type exhaust take-off fitting to which our co-pending patent application no. 38285/77 refers.Serial no 1599658 Welded or otherwise secured to and depending from the upper fire-tube carrier plate 32 is a cylindrical water shield 34 surrounding the nest of fire-tubes and extending downwardly to a lower edge 36 spaced by a predetermined desired amount from the top side of the fire-box. As shown, the width or diameter of the water shield 34 is significantly less than that of the fire-box itself to a desired or convenient extent. The fire-box 18 has about its upper part a cylindrical water shield 40 at a relatively close predetermined spacing therefrom and extending upwardly above the fire-box and above the lower edge 36 of the fire-tube water shield 34.The spacing of the shield 40 relative to the fire-box is determined by discrete spacers 42 at or near its lower edge and discrete bracket-like spacers and mounts 44 engaging the upper edge of the fire-box or lower fire-tube carrier plate. The above-mentioned predetermined desired spacings and shield overlap serve to set the amount of water passing over the fire-box exterior and into and past the fire-tube water shield 34 for release via weir notches 45 at its upper edge serving also for air expulsion on boiler filling and also via upper apertures 46 in the water shield 34 and through tubes 48 to apertures 50 of tappings for boiler flow in the outer shell. Water return or supply tappings 51 for the boiler are shown at a lower part thereof below the side level of the concave base 52 of the fire-box.The allowed water flow is adequate to permit sufficient natural and/or forced water circulation to provide a safe quantity of water within those shields and yet limit that quantity at low water temperatures to ensure a minimum of condensation within the fire-tubes and firebox of sulphurous products of combustion normally largely responsible for corrosion. It is convenient to provide a boiler temperature limiting thermostat mount through tapping 54 in the lower and overlapped part of the fire-tube water shield 34. A direct outlet 55 may be provided from the water shield itself for high heating loads irrespective of overall boilder water temperature, say to a primary feed for indirect hot water cylinders or calorifier. Then. it is also convenient to provide a primary water flow control thermostat mount through tapping 56 in the outer shell and into the water shield 34, such control being via a pump or valve. The fact that the water shield 34 depends from the underside of the upper carrier plate 32 with the fire-tubes 28 extending through the latter means that there is a minimum of water backed surface at and adjacent to the smoke-box 34 so as to limit condensation therein which might otherwise find its way into the fire-tubes. The unit conveniently rest on feet 58. Air bleed valve or water vent tappings may be provided through the upper fire-tube carrier plate as desired, and a boiler drain connection is indicated at 60, which will be at a lower position on the outer shell 16. WHAT WE CLAIM IS:

1. A hot water boiler and heat exchanger unit having an outer water-accommodating shell within which is disposed a fire-box from which a nest of fire-tubes extends upwardly through the shell to a smoke-box, wherein a water shield fitted about the nest of fire-tubes has a lower edge or edges spaced above an upper part of the fire-box so as to control entry of water to the interior of the water shield.

10. A unit according to claim 9, wherein

the further water shield is located and spaced relative to sides of the fire-box by way of lower discrete spacers and, above those spacers, by brackets resting on upper edge parts of the fire-box.

11. A unit according to claim 9 or claim 10, wherein the further water-shield extends upwardly above the lower edge or edges of the first-mentioned water shield.

12. A unit according to any preceding claim, wherein the water shield about the nest of fire-tubes is spaced inwardly of the exterior dimensions of the fire-box.

13. A unit according to claim 12 with claim 11, wherein the further water-shield extends wholly substantially parallel with sides of the fire-box.

14. A hot water boiler and heat exchanger unit arranged and adapted to operate substantially as herein described with reference to and as shown in the accompanying drawings.