GB2039356A - Heat exchanger eg for a boiler flue - Google Patents

Abstract

A heat exchanger comprises a jacket 4, Figure 1, which is designed to fit round a boiler flue so that heat which would otherwise go to waste in the gases passing through the flue can be extracted by coolant (eg water) passing through the heat exchanger jacket and put to use. The jacket is provided with a coolant inlet 5 at its lower end and a coolant outlet 6 at its upper end. So that already existing flues may be fitted, another form of the heat exchanger, shown in plan view in Figure 7, comprises a jacket (20) in two pieces which can be clamped together around a chosen section of the flue by means of brackets (23). Each piece is of double walled construction to define a coolant passage 21 between the two walls. The jacket is thickened at 22 at the top and the bottom to accommodate tapping for the fixing of external pipe work to the inlet and outlet. <IMAGE>

Description

SPECIFICATION Heat exchangers The present invention relates to a heat exchanger particularly, but not exclusively, intended for use as a section of a boiler flue.

With the ever increasing cost of fuel, and the steady decline of fossil fuel reserves it is becoming more and more important for the most efficient use to be made of fuel being burnt. Great efforts have already been made to this end to reduce heat loss in building so that as far as possible most of the heat generated by burning fuel is used for the intended purpose and not simply thrown away. In most boilers, however, a large part of the heat produced in the combustion process is thrown away with the waste gases through the boiler flue.

According to the present invention there is provided a heat exchanger comprising a central pipe section through which products of combustion may pass, a coolant jacket partially or wholly surrounding the section, and coolant inlet and coolant outlet means in the jacket.

A preferred embodiment of the invention may comprise any one or more of the following advantageous features: (a) The pipe comprises a tubular metal section.

(b) The inlet and outlet means are tapped for the connection of external pipework.

(c) The pipe section and jacket are concentrically arranged.

(d) The jacket is in two parts clamped together around the pipe section.

In order that the invention may be more clearly understood, two embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which Figure 1 shows a rear elevation of a boiler flue section incorporating a heat exchanger, Figure 2 shows a side elevation in section of the section of Figure 1, Figure 3 shows a plan view of the section of Figures 1 and 2, Figure 4 shows a side elevation of the section of Figure 1, Figure 5 shows a side elevation of a part of an alternative embodiment to that shown in Figures 1 to 4, Figure 6 shows a rear elevation of the part shown in Figure 1, Figure 7 shows a plan view of two parts of the type shown in Figures 5 and 6 joined together, and Figure 8 shows a plan view of the two parts of Figure 7 spaced apart.

Referring to the drawing, the section 1 is of tubular metal and comprises collar 2 at its upper end and a spigot 3 at its lower end. Surrounding the section is a coolant jacket 4 having an inlet 5 at its lower end and an outlet 6 at its upper end. Both the section 1 and jacket 4 are of circular cross-section and both are concentrically arranged. The inlet 5 and outlet 6 are tapped to accommodate external pipework for conveying coolant (usually water) to and from the jacket A Tk metal nf thsL inoknt t 3runt thp inlet F; Rnd the outlet 6 is thickened to accept the tapping.

The jacket may be made in two pieces bolted back to back together rather than the one piece arrangement shown in Figures 1 to 4 above. Such a two-piece arrangement is shown in Figures 5 to 8 and facilitates the application of the invention to an already existing boiler installation. The two pieces each constitute one half of a collant jacket 20. Each piece is of double walled construction to define a coolant passage 21 between the two walls. One edge 22 of each piece is thickened at the top and bottom to accommodate tapping for the fixing of external pipework as described in the first embodiment and the other edge of each piece carries a bracket 23 to enable the two pieces to be clamped together around a chosen section of the boiler flue. The coolant inlet and outlet are respectively referenced 24and25.

In operation of both embodiments heat from the boiler exhaust gases flowing up the flue in the direction of the arrow is transferred to coolant flowing in the direction of the arrow through the coolant jacket. In both embodiments, it is important that the top tapping (the outlet) is the highest point in the coolant way thus making it impossible for air to be trapped in the jacket when being filled with coolant.

It will be appreciated that the above embodiments have been described by way of example only and that many variations are possible without departing from the scope of the invention.

1. A heat exchanger comprising a central pipe section through which products of combustion may pass, a coolant jacket partially or wholly surrounding the section and coolant inlet, and coolant outlet means in the jacket.

2. A heat exchanger as claimed in claim 1, in which the pipe comprises a tubular metal section.

3. A heat exchanger as claimed in claims 1 to 2, in which the inlet and outlet means are tapped for the connection of external pipe work.

4. A heat exchanger as claimed in claims 1,2 or 3, in which the pipe section and jacket are concentrically arranged.

5. A heat exchanger as claimed in any preceding claim, in which the jacket is in two parts clamped together around the pipe section.

6. A heat exchanger substantially as hereinbefore described with reference to the accompanying drawings.

7. A boiler flue comprising a heat exchanger as claimed in any preceding claim.

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

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Heat exchangers The present invention relates to a heat exchanger particularly, but not exclusively, intended for use as a section of a boiler flue. With the ever increasing cost of fuel, and the steady decline of fossil fuel reserves it is becoming more and more important for the most efficient use to be made of fuel being burnt. Great efforts have already been made to this end to reduce heat loss in building so that as far as possible most of the heat generated by burning fuel is used for the intended purpose and not simply thrown away. In most boilers, however, a large part of the heat produced in the combustion process is thrown away with the waste gases through the boiler flue. According to the present invention there is provided a heat exchanger comprising a central pipe section through which products of combustion may pass, a coolant jacket partially or wholly surrounding the section, and coolant inlet and coolant outlet means in the jacket. A preferred embodiment of the invention may comprise any one or more of the following advantageous features: (a) The pipe comprises a tubular metal section. (b) The inlet and outlet means are tapped for the connection of external pipework. (c) The pipe section and jacket are concentrically arranged. (d) The jacket is in two parts clamped together around the pipe section. In order that the invention may be more clearly understood, two embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which Figure 1 shows a rear elevation of a boiler flue section incorporating a heat exchanger, Figure 2 shows a side elevation in section of the section of Figure 1, Figure 3 shows a plan view of the section of Figures 1 and 2, Figure 4 shows a side elevation of the section of Figure 1, Figure 5 shows a side elevation of a part of an alternative embodiment to that shown in Figures 1 to 4, Figure 6 shows a rear elevation of the part shown in Figure 1, Figure 7 shows a plan view of two parts of the type shown in Figures 5 and 6 joined together, and Figure 8 shows a plan view of the two parts of Figure 7 spaced apart. Referring to the drawing, the section 1 is of tubular metal and comprises collar 2 at its upper end and a spigot 3 at its lower end. Surrounding the section is a coolant jacket 4 having an inlet 5 at its lower end and an outlet 6 at its upper end. Both the section 1 and jacket 4 are of circular cross-section and both are concentrically arranged. The inlet 5 and outlet 6 are tapped to accommodate external pipework for conveying coolant (usually water) to and from the jacket A Tk metal nf thsL inoknt t 3runt thp inlet F; Rnd the outlet 6 is thickened to accept the tapping. The jacket may be made in two pieces bolted back to back together rather than the one piece arrangement shown in Figures 1 to 4 above. Such a two-piece arrangement is shown in Figures 5 to 8 and facilitates the application of the invention to an already existing boiler installation. The two pieces each constitute one half of a collant jacket 20. Each piece is of double walled construction to define a coolant passage 21 between the two walls. One edge 22 of each piece is thickened at the top and bottom to accommodate tapping for the fixing of external pipework as described in the first embodiment and the other edge of each piece carries a bracket 23 to enable the two pieces to be clamped together around a chosen section of the boiler flue. The coolant inlet and outlet are respectively referenced 24and25. In operation of both embodiments heat from the boiler exhaust gases flowing up the flue in the direction of the arrow is transferred to coolant flowing in the direction of the arrow through the coolant jacket. In both embodiments, it is important that the top tapping (the outlet) is the highest point in the coolant way thus making it impossible for air to be trapped in the jacket when being filled with coolant. It will be appreciated that the above embodiments have been described by way of example only and that many variations are possible without departing from the scope of the invention. CLAIMS

1. A heat exchanger comprising a central pipe section through which products of combustion may pass, a coolant jacket partially or wholly surrounding the section and coolant inlet, and coolant outlet means in the jacket.

2. A heat exchanger as claimed in claim 1, in which the pipe comprises a tubular metal section.

3. A heat exchanger as claimed in claims 1 to 2, in which the inlet and outlet means are tapped for the connection of external pipe work.

4. A heat exchanger as claimed in claims 1,2 or 3, in which the pipe section and jacket are concentrically arranged.

5. A heat exchanger as claimed in any preceding claim, in which the jacket is in two parts clamped together around the pipe section.

6. A heat exchanger substantially as hereinbefore described with reference to the accompanying drawings.

7. A boiler flue comprising a heat exchanger as claimed in any preceding claim.