GB2271834A - Boiler - Google Patents

Abstract

In a boiler, a timer or a bimetallic element 6 causes a by-pass between turbulators 4A and an adjacent heat exchange wall, or defined by an opening (7, Fig 1 not shown) in a baffle 4, to open during start-up of the boiler to prevent condensation in flue 8. The element 6 may be thermally insulated to delay its actuation. The element 6 may be used to maintain a set exhaust temperature under varying boiler load conditions. <IMAGE>

Description

"Heat Exchangers." THIS INVENTION relates to heat exchangers: In a typical boiler in which water is to be heated, baffles, turbulators, methods of increasing the effective surface area of the boiler or other techniques are used to increase the thermal efficiency of the boiler.

A disadvantage of prior art of heat exchange is that to achieve higher efficiency the flue gas temperature exhausted from the boiler is close to its point of condensation. In the shoulder months, or under other light load conditions, when the boiler is only fired for short periods of time, there is insufficient time for the chimney to heat up and even with efficient Insulated chimneys condensation can occur. The present invention seeks to provide an improvement in which the drawbacks and disadvantages of the prior art are obviated or reduced.

According to the present invention there is provided means actuated by time delay and or the exhaust temperature of the hot products of combustion to vary the thermal efficiency of a boiler.

Preferably the said means causes at least some of the hot products of combustion to bypass at least some of the heat exchange processes of a boiler.

Usefully the said means varies the spacing between turbulators and or flue gas path guide plates and the heat exchange wall of a boiler, Advantageously the said means is a removable component or is part of a removable component.

Conveniently the said means Is actuated by a bi-metal component.

Advantageously the bl-metal component is insulated to delay the actuation of the said means.

To facilltate better understanding of the invention and so its features may be appreciated the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a cross sectional view through a boiler incorporating the present invention, showing the means to bypass the hot products of combustion in the cold or open position.

Figure 2 is a cross sectional view of the boiler of Figure 1 showing the means to bypass the hot products of combustion in the hot or closed position.

Figure 3 Is a detailed view of a baffle incorporating the present invention.

Referring first to Figure 1 of the accompanying drawings there Is shown a boiler 1. provided with a burner 2. from which hot gases of combustion flow past the prlmary baffle 3. via heat exchange path 3a. after which the maJorlty of hot products of combustion pass through the open bypass port 7. in the secondary baffle 4.

Affixed to the secondary baffle 4. is a metal strip 6. which has attached to It a bypass port closure plate 5. which, in its cold state shown in Figure 1, is open permitting the majority of the hot products of combustion to exit directly to the flue 8., thereby bypassing the secondary flue pass 4a. Upon boiler light up from cold elevated flue gas temperatures are swiftly achieved, avoiding condensation formation within the chimney by heating the chimney up before the bi-metal strip 6. on the top baffle 4.

heats and as shown in Figure 2, closes the closure plate 5.

across the bypass port 7. causing the hot products of combustion to follow the longer path through the second pass 4a. giving the boiler full efficiency once the flue system has reached temperature.

Figures 3 and 4 show an application where the thermal efficiency is varied by a bi-metal strip varying the spacing between turbulators and the flue path 4a and the heat exchange wall Although the illustrations show open or closed states, it should be understood that the states may be progressively varied to maintain a set exhaust temperature under varying boiler load conditions. It may also be applied to larger commercial boilers where the bypass actuation may be taken remotely from electronic or mechanical sensors and actuators while the bypass may be an integral part of the boiler structure rather than a simple baffle incorporated form illustrated here.

Claims (5)

1. Means actuated by time delay and or the exhaust temperature of the hot products of combustion to vary the thermal efficiency of a boiler.

2. Means according to Claim I causing at least some of the hot products of combustion to bypass at least some of the heat exchange processes of a boiler.

3. Means according to Claim 1 varylng the spacing between turbulators and or flue gas path guide plates and the heat exchange wall of a boiler.

4. Means according to the prevlous claims that is a removable component or is part of a removable component.

5. Means according to the previous claims actuated by a bi-metal component.

Means according to the previous claim wherein the bi-metal component is insulated to delay the actuation of the said means.