GB2164429A - Gas-fired water heaters - Google Patents

Abstract

A gas-fired water heating apparatus comprises a central combustion chamber 10 in communication with a surrounding combustion products flow passage 19 adapted to be ducted to a flue. A water flow passage 12 encloses both the combustion chamber and the combustion products flow passage, the combustion chamber having, at one end, a high intensity gas burner 16 with the inlet to the combustion products passage at the other end of the combustion chamber, the latter and the combustion products passage being spaced to provide therebetween a passage for water. The high intensity burner is a swirl or vortex burner, and a high pressure fan provides a forced air supply to the burner along a pipe into which gas, is injected. The high pressure fan is a toroidal fan. <IMAGE>

Description

SPECIFICATION Water heating apparatus This invention relates to water heating apparatus, and in particular gas-fired water heating apparatus.

It is an object to provide a gas-fired water heating apparatus of greater heat-exchange efficiency than those currently in use.

According to the present invention there is provided a gas fired water heating apparatus comprising a central combustion chamber in communication with a surrounding combustion products flow passage adapted to be ducted to a flue, and a water flow passage enclosing both the combustion chamber and the combustion products passage, the arrangement being such that the combustion products and water are in counter-flow, the combustion chamber having, at one end, a high intensity gaa burner with the inlet to the combustion products passage at the other end of the combustion chamber, the latter and the combustion products passage being spaced to provide therebetween a passage for water.

Preferably the high intensity burner is a swirl or vortex burner.

Preferably a high pressure fan provides a forced air supply to the burner along a pipe into which gas is injected.

Preferably the high pressure fan is a toroidal fan.

The gas may alternatively be injected directly into the fan which then feeds the high pressure air/gas mixture to the swirl burner.

Preferably, the apparatus comprises a casing within which the combustion chamber and the combustion products passage are housed in spaced relationship from the casing wall(s) to define therebetween the water passage.

Preferably, the combustion products passage is of spiral or helical configuration spatially surrounding the combustion chamber along the length thereof, the casing spatially surrounding the combustion chamber and the combustion products passage with a water inlet adjacent the gas burner end of the combustion chamber and a water outlet adjacent the combustion products passage inlet of the combustion chamber.

The inner combustion products passage and the outer water passage may be simple open parallel passages, for example spaced annular passages.

The combustion products passage may, as aforesaid, be spiral or helical within an uninterrupted water passage defined by the combustion chamber and casing.

In a modification the water passage contains a spiral or helical fin arranged between the spirals of the combustion products passage to define a spiral or helical water passage between the combustion chamber and the casing.

The combustion products passage may be defined by a compartment having along its axial length alternate relatively wide and relatively narrow sections.

The combustion products and water passages may be defined by a chamber divided internally to provide alternative spiral or-helical flow passages for the combustion products and water respectively, the chamber being itself surrounded by a water passage.

In all the aforesaid arrangements, it will be manifest that the combustion products are surrounded by water.

The present invention envisages also a central heating boiler incorporating a water heating apparatus as defined in the preceding paragraphs and the present invention includes such a central heating boiler. The latter may also have a domestic hot water supply facility.

Embodiments of the present invention will -now be described, by way of example, with reference to the accompanying drawings, in which Fig. 1 is a diagrammatic view of one form of water heating apparatus according to the invention; Fig. 2 is a similar view, in greater detail, of a modified water heating apparatus; Fig. 3 is a plan view corresponding to Fig.

2; Fig. 4 is a diagrammatic view of a central heating and domestic hot water boiler incorporating the water heating apparatus according to the invention; and Figs. 5 to 7 are detail diagrammatic views showing alternative combustion product and water passage arrangements.

Referring to Fig. 1, the hot water heating apparatus or circulator comprises a cylindrical combustion chamber 10 and a surrounding casing 11 radially spaced from the combustion chamber 10 and defining with it an annular water passage 12, the water inlet 13 being at the lower end of the casing 11 and the water outlet 14 at the top.

The casing 11 is externally insulated as indicated at 15.

Within the combustion chamber 10 is a high intensity swirl or vortex gas burner 16 to which is piped as indicated at 17 high pressure air from a suitable fan (not shown). Gas is injected into the high pressure air stream as indicated at 18.

A heat exchanger through which flows the combustion products from the gas burner 16 comprises a spiral or helical tube 19 disposed within the annular water passage 12 radially spaced from the combustion chamber 10 and the casing 11. The tube 19 surrounds the combustion chamber 10 and communicates therewith as indicated at 20 at the upper end of the chamber 10. The tube (heat exchanger) outlet is indicated at 21 and extends out of the casing 11 and insulation 15 adjacent the water inlet 13 for connection to a flue (not shown).

With this apparatus or circulator, the water may be pumped into the casing 11 but this is not essential, normal convection causing the hot water to flow out of the top of the circulator to be replaced by cold water.

The enclosure of the heat exchanger (hot gases) by the water to be heated ensures a high efficient rate of heat exchange. A figure in excess of 90% efficiency is considered most feasible.

Referring now to Figs. 2 and 3, parts similar to those in Fig. 1 are indicated by the same references with the suffix "A".

In these Figs. 2 and 3, the high pressure fan is indicated at 22 and it is preferred that the fan 22 is a toroidal fan.

To improve the rate of heat exchange, the annular water passage 12A has a spiral fin 23 arranged therein extending between the combustion chamber 10A and the casing 11A. In this way the flow of water to be heated spirals upwardly from the water inlet 1 3A to the water outlet 1 4A while the combustion products from the combustion chamber 10A spiral downwards through the heat exchanger 19A from inlet 20A to outlet 21A.

A convenient control system for the high intensity swirl or vortex burner is a non-pilot flame, two flame rectification system. When the high pressure toroidal fan is switched on and a predetermined air pressure is attained a pressure switch (not shown) is operated to cause gas to flow to the burner and a spark ignition to operate. When the flame of the burner is sensed by an electrode (not shown) to be stable operation of the burner is maintained.

The water heating apparatus is cycled on and off by any convenient means, for example a thermostat control or timer.

The high pressure toroidal fan provides sufficient air pressure not only to feed combustion air to the burner but also to drive the combustion products through a flue system.

Due to the nature of the fan this flue system can be of relatively extended length which is useful if the water heating apparatus is disposed some distance from an external wall or roof. Also due to the nature of the fan and the substantial high pressure, high volume of air generated thereby the combustion products have a temperature of the order of 30"C and consequently the flue system can be formed of a convenient plastics material.

The water heating apparatus according to the invention is considered to have an efficiency in excess of 90%, possibly 95% since there are no external heat losses due to water jacket and/or insulated jacket 15 or due to the fact that the apparatus is disposed within a water cistern.

With the apparatus or circulator of Figs. 2 and 3 the water is pumped along its spiral path.

It is to be noted that with this apparatus or circulator which can be used merely for supplying hot water and/or for space heating purposes, the toroidal fan 22, the controls and the circulator can all be disposed in separate remote locations to suit the physical requirements of the premises within which-they are provided. The may also, of course, be provided as a package.

The spiral or helical fin 23 may be of planar construction or corrugated construction.

In Fig. 4, there is shown a central heating boiler comprising a cylinder 24 within which is located a hot water circulator 25 as described with reference to Fig. 1 or Figs. 2 and 3.

The circulator heated water outlet indicated at 26 has connected thereto a vertical pipe 27 to direct outflow of the heated water to the upper end of the cylinder 24. The outlet from the cylinder 24 to the hot water radiator system (not shown) is indicated at 28 while the return from the radiator system is indicated at 29.

The cylinder 24 is of the known type having a cold water infeed pipe 30 connected to a helical or spiral internal pipe 31 within the cylinder 24, which internal pipe 31 has a hot water outlet pipe 32 for supplying domestic hot water. Pipes 30 and 32 are connected by a pipe 33 incorporating a one-way valve 34 to permit flow of cold water towards the hot water pipe 32 which includes at the junction with the pipe 33 a mixing valve 35.

Above the cylinder 24 is an overflow tank 36 to which the cylinder 24 is connected by an overflow pipe 37.

The cylinder 24 and overflow tank 36 are insulated as indicated at 38.

It will be noted that the circulator 25 is housed within the cylinder 24 so that external heat losses are obviated or, if present, are into the water within the cylinder 24.

No external piping between the circulator 25 and the cylinder 24 is required so that cost of production is reduced.

To cope with larger sized cylinders 24 it is only necessary to increase the size of the swirl or vortex burner of the circulator 25 and to increase the rate of flow of high pressure air from the toroidal fan.

Reference is now made to Figs. 5 to 7.

In Fig. 5, the combustion chamber 37 is connected by transfer ports 38 to an annular heat exchange chamber 39 surrounded by an annular water chamber 40.

In Fig. 6, the heat exchange chamber 41 has alternate, in the axial direction, relatively wide and relatively narrow regions 42, 43 respectively, and is again located within an annular water chamber generally indicated by arrow 44.

In Fig. 6, there is between -the combustion chamber 45 and the casing 46 an annular water passage 47 within which is a compartmentalised annular chamber 48 defining alter nate spiral or helical combustion product and water passes designated 49 and 50 respectively, i.e. an integrated heat exchanger.

The water heating apparatus or circulator according to the present invention may be employed domestically or industrially.

For the avoidance of doubt the term "water" is to be construed as including within its scope any suitable liquid separately or in mixture with water.

Claims (14)

1. A gas-fired water heating apparatus comprising a central combustion chamber in communication with a surrounding combustion products flow passage adapted to be ducted to a flue, and a water flow passage enclosing both the combustion chamber and the combustion products flow passage, the combustion chamber having, at one end, a high intensity gas burner with the inlet to the combustion products passage at the other end of the combustion chamber, the latter and the combustion products passage being spaced to provide therebetween a passage for water.

2. Apparatus as claimed in claim 1, in which the high intensity burner is a swirl or vortex burner.

3. Apparatus as claimed in claim 1 or 2, comprising a high pressure fan providing a forced air supply to the burner along a pipe into which gas, is injected.

4. Apparatus as claimed in claim 3, in which the high pressure fan is a toroidal fan.

5. Apparatus as claimed in any one of claims 1 to 4, comprising a casing within which the combustion chamber and the combustion products passage are housed in spaced relationship from the casing wall(s) to define therebetween the water passage.

6. Apparatus as claimed in claim 5, in which the combustion products and the water are in counterflow.

7. Apparatus as claimed in claim 5 or 6, in which the combustion products passage is of spiral or helical configuration spatially surrounding the combustion chamber along the length thereof, the casing spatially surrounding the combustion chamber and the combustion products passage with a water inlet adjacent the gas burner end of the combustion chamber and a water outlet adjacent the combustion products passage inlet of the combustion chamber.

8. Apparatus as claimed in claim 7, in which the combustion products passage and the water passage are open parallel passages, for example, spaced annular passages.

9. Apparatus as claimed in claim 7, in which the water passage contains a spiral or helical fin arranged between the spirals of the combustion products passage to define a spiral or helical water passage between the combustion chamber and the casing.

10. Apparatus as claimed in any one of claims 1 to 9, in which the combustion products passage is defined by a compartment having along its axial length alternate relatively wide and relatively narrow sections.

11. Apparatus as claimed in claim 1, in which the combustion products and water passages are defined by a chamber divided internally to provide alternative spiral or helical flow passages for the combustion products and water respectively, the chamber being itself surrounded by a water passage.

12. A gas fired water heating apparatus, substantially as hereinbefore described with reference to the accompanying drawings.

13. A central heating boiler incorporating a gas-fired water heating apparatus as claimed in any one of claims 1 to 12.

14. A central heating boiler as claimed in claim 13 having a domestic hot water supply facility.