GB2146104A - Liquid heater - Google Patents

Abstract

A liquid heater, for example for heating and regenerating a liquid absorbent, e.g. triethylene glycol, in which a jacket 21 for the liquid to be heated surrounds a firebox 18 having a burner 20 at one end. Return tubes 22 extend through said jacket and open at one end 24, 25 remote from the burner into the firebox and some of the tubes open again at their other ends 26 into the firebox closely adjacent to the burner so that the combustion products of the burner draw combustion products through these return tubes to heat liquid in the jacket. <IMAGE>

Description

SPECIFICATION Liquid heater The present invention relates to liquid heaters for heating any liquid, for example a liquid absorbent such as triethylene glycol.

Problems arise with known forms of heaters in that they are relatively expensive and can produce hot spots causing degradation of the iiquids to be heated.

It is now proposed, according to the present invention, to provide a liquid heater comprising a firebox, a jacket for the liquid to be heated surrounding said firebox, a fuel burner at one end of the firebox for projecting the products of combustion axially forwardly, into said firebox, a plurality of return tubes extending through said jacket and each opening at one of its ends into said firebox at a location remote from said burner, at least some of said return tubes opening at their o,ther ends at a location adjacent said burner, whereby the flow of combustion products from the burner draws combustion gases from said other ends of said at least some tubes thereby to induce a flow of gas in said at least some return tubes from said one end to said other end thereof.

With such a construction a great deal of heat can be imparted to the liquid in the jacket firstly from the walls of the firebox itself and secondiy from the return tubes through which the gas is induced to flow by the suction effect of the burner itself operating close to the other end of some of the return tubes. Thus the products of combustion are sucked through and without there being any need for any external fan or the like to induce this flow. The burner itself is preferably of the so called "High intensity" type so it produces a considerable flow rate of the products of combustion thereby inducing a good flow through the return tubes.

The remainder of the tubes may also pass through the jacket so that the spent products of combustion can be exhausted through these other return tubes and thereby give up their heat on there way to the exhaust flue.

In a preferred construction all of the tubes extend in spaced substantially parallel relation through the jacket so that they are substantially parallel to the axis of the firebox. This gives a compact structure and good heat exchange properties.

In order to induce a good flow of gas through the said returned tubes, the ends thereof adjacent to the burner are preferably inclined radially inwardly and forwardly where they open into the firebox. In this way the gas flowing from the burner is moving in substantially the same direction as the gas which is drawn through these return tubes. At the other end all of the return tubes are preferably inclined radially inwardly and towards the burner to facilitate the flow of the products of combustion through the return tubes whether they be those through which gas is drawn by the action of the burner, or the remainder through which the combustion products flow on their way to the exhaust flue.

In order that the invention may be more readily understood, the following description is given, merely by way of example, reference being made to the accompanying drawing which is a schematic cross-section through one embodiment of liquid heater according to the invention.

The apparatus illustrated in the drawing is one for regenerating a liquid absorbent and includes a skid (10) a storage tank (11) a stripping column (12) connected to a vapor space (13) having an access door (14) and a still column (15). These components are all largely conventional.

Mounted to the left of the storage tank (11) and thermally separated therefrom by an isolating plate (16) is the heater construction indicated by the general reference (17) according to the present invention. This includes a firebox (18) of generally elongate cylindrical configuration and having an end cap (1 9) at its right-hand end and a high intensity burner (20) at its left-hand end. The firebox (18) is mounted within a jacket (21) for the liquid to be heated which is connected to the vapor space (14).

Extending longitudinally within the jacket and generally parallel to one another are return tubes (22) and exit tubes (23). The return tubes and exit tubes are each connected at one of their ends (24) to the interior of the firebox (18), these ends being inclined inwardly and rearwardly towards the burner (20). The return tubes (22) are connected at the other end (26) to the firebox (18), these ends (26) being inclined inwardly and forwardly that is to the right as seen in the drawings.

The exit tubes (23), on the other hand, are connected to a manifold (27) having an exhaust flue (28) which has a downdraft diverter (29) at its upper end.

The burner (20) is supplied with fuel through means (not shown) and a forced draft is induced by a fan indicated generally at (30). Details of the burner and the forced draft do not form part of this present invention and further discussion of them is not deemed necessary.

The burner (20), however, does have a discharge nozzle (31), which is closely adjacent to the ends (26) of the return tube 22.

In use liquid to be heated is introduced in the usual way into the storage tank (11) and finds its way into jacket (21).

The fuel is combusted in the conventional manner and a discharge jet flows very forcefully from the nozzle (31) to the right along the axis of the firebox (18). This has the effect of inducing a suction at the ends (26) of the return tubes so that the products of combustion are drawn into the ends (24) thereof thereby inducing a good steady flow of products of combustion through the tubes (22).

The liquid in the jacket (21) is heated firstly by heat exchange with the external surface of the firebox and secondly by heat exchange with the return tubes (22). Some of the products of combustion will discharge via the tubes (23) into the manifold (27) and then out of the flue (28).

It will be noted that the tubes (22, 23) are generally parallel to one another and that their inlet ends (24), (25) are inclined towards the burner to faciiitate the introduction of the products of combustion there into. The shaping of the ends 26 of the return tubes is such as to encourage flow of gas through the return tubes.

Claims (6)

1. A liquid heater comprising a firebox, a jacket for the liquid to be heated surrounding said firebox, a fuel burner at one end of the firebox for projecting the products of combustion axially forwardly, into said firebox, a plurality of return tubes extending through said jacket and each opening at one of its ends into said firebox at a location remote from said burner, at least some of said return tubes opening at their other ends at a location adjacent said burner, whereby the flow of combustion products from the burner draws combustion gases from said other ends of said at least some tubes thereby to induce a flow of gas in said at least some return tubes from said one end to said other end thereof.

2. A liquid heater according to claim 1, wherein the remainder of said tubes also pass through said jacket and direct products of combustion to an exhaust flue.

3. A liquid heater according to claim 1 or 2, wherein all the said tubes extend in spaced, substantially parallel relation through said jacket, substantially parallel to the axis of the firebox.

4. A liquid heater according to claim 1, 2 or 3, wherein said other ends of said at least some return tubes are inclined inwardly and forwardly where they open into said firebox.

5. A liquid heater according to any preceeding claim, wherein said one ends of said return tubes are inclined radially inwardly and rearwardly towards said burner as they open into said firebox.

6. A liquid heater substantially as hereinbefore described with reference to and illustrated in the accompanying drawings.