GB2113814A

GB2113814A - Waste heat utilisation

Info

Publication number: GB2113814A
Application number: GB08201696A
Authority: GB
Inventors: Robert Victor Stevens; Michael Lawrence Stevens
Original assignee: LEERCO ENGINEERING Ltd
Current assignee: LEERCO ENGINEERING Ltd
Priority date: 1982-01-21
Filing date: 1982-01-21
Publication date: 1983-08-10
Also published as: GB2113814B

Abstract

In or for a furnace particularly of the Lehr type for heat treating articles, such as glassware, in which air is used as a cooling medium, a heat exchanger including a valve 38 so that cooling air may be selectively passed through the heat exchanger to transfer heat from the cooling air to a liquid medium such as water. <IMAGE>

Description

SPECIFICATION Furnace and apparatus therefor The present invention relates to a furnace, particularly a furnace of the type referred to as a Lehr furnace and parts therefor.

Lehr furnaces are normally used for annealing glassware or for heat treating glassware after a printed decoration has been applied to it. The glassware is passed through the furnace and through different heat treatment zones, and in at least one zone the glassware is cooled by passing recirculated air over the glassware. The recirculating air is cooled by heat transferring walls and the walls are cooled by cooling air which is thereby heated and then extracted from the furnace.

The present invention provides a furnace particularly of the Lehr type for heat treating articles, for example, glassware, air being used as a cooling medium, means being provided to collect said cooling air after it has been heated, and ducting means including valve means to alternately direct the collected air to an outlet means or to a heat exchanger, the heat exchanger comprising a duct through which the heated air may pass, and means through which water or another liquid medium passes, heat from the air being transferred to the water, temperature measuring means being provided to determine if the temperature of the water is above a predetermined level, said temperature measuring means being used to control a motor means which operates the valve means so that when the water reaches said predetermined temperature the valve is operated to pass the heated air to the outlet means.

The valve means may comprise a flap valve in which all of the air may be passed to the outlet means when the water reaches the predetermined temperature. There are considerable advantages in the arrangement of the invention. In the past it has been common that the heated air simply passes outof the top of the furnace into the building in which the furnace is situated which can provide an unnecessary degree of heating particularly in the summer months. With the present arrangement, the heat from the heated air is extracted by the water and can be used, for example, to provide hot water for the factory in which the furnace is provided, or, in the winter time, to provide space heating which may be more readily controlled than the simple exhaust of hot air from the furnace.

The invention also provides a unit for attachment to the furnace comprising means for attachment to the hot air outlet of the furnace, the heat exchanger, the valve means, and the temperature measuring means.

A preferred embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings, in which: FIGURE 1 shows a perspective view of a Lehr type furnace incorporating the invention, and, FIGURE 2 shows a perspective view partially cut away, of part of the furnace shown in FIGURE 1.

Referring to the figures, there illustrated a Lehr type furnace 11, which is in the form of a tunnel through which a conveyor 1 2 of wire mesh passes on which may be mounted articles such as glass bottles which are to be annealed or decorated. The entrance end of the furnace 11 is indicated at 1 3 and the conveyor 1 2 moves in the direction of the arrow 14.

As is clear from FIGURE 1 the furnace is divided into a number of sections, the first three sections, 1 6, 1 7, 1 8, being heating sections in which the articles on the conveyor 1 2 are heated by means of air circulation which passes over heating elements. The air is circulated by means of the recirculating fans driven by motors 1 9.

The articles on the conveyor 1 2 are then cooled by cooling sections 21, 22, which will be described in detail later. There is provided a tunnel pressure section 23 and a further cooling section 24 and finally a blast cooling section 26 in which ambient air is forced over the articles on the conveyor.

Referring back to the cooling sections 21, 22, which are of identical construction, cold ambient air is drawn in by motor driven fan 27 and passes around the walls of the cooling sections 24 so as to cool the walls. Air within the furnace is circulated around and past the walls by recirculating fans driven by motors 25 and is thereby cooled by the walls. The articles are therefore cooled indirectly.

The air which has been used to cool the walls and is thereby heated by them is pumped out of the top of each cooling section 24 into a cooling apparatus 28 to be described.

The cooling apparatus which is illustrated in detail in FIGURE 2 comprises an inlet duct 31 including flange 32 for connection to the top of the cooling section 21 or 22 and above the inlet duct 31 is mounted a flap valve unit 33 which includes a flap valve 38 pivoted at 34 and being of such dimensions as to be able to extend across the duct. The flap valve unit 33 includes an outlet grill 36 and to the top of the flap valve unit 33 is mounted a heat exchanger 37. The flap valve 38 within the flap valve unit 33 may be moved between two positions, one of which is illustrated at A, and other which is illustrated at position B.In position A the flap valve 38 prevents air from the inlet duct 31 passing up to the heat exchanger unit in which case the air is directed out of the outlet grill 36 and in position B the outlet grill 36 is closed off and the air from the inlet duct 31 is directed upwardly into the heat exchanger 37.

The heat exchanger 37 comprises an outer duct 41, through which passes two water pipes 42, 43 of copper, the water pipes 42, 43 carrying fins 46, also copper. Outside the duct 41 the two pipes 42, 43 are connected together by manifolds 47, 48 and hence to inlet and outlet pipes 51, 52, the outlet pipe 52 carrying a temperature sensing means 53.

There is also provided a motor 54 which rotates a linkage 56 to rotate the flap valve 38 about its pivot 34.

Above the heat exchanger 37 is mounted an outlet valve 57 comprising a one way gravity operated flap valve.

In use, therefore, heated cooling air from the respective cooling section 21 or 22 passes upwardly through the inlet duct 31, and at least initially the flap valve 38 is in position B so that the air is directed upwardly through the heat exchanger 37. Water passes from the inlet pipe 51 to the outlet pipe 52 through water pipes 42, 43, heat being extracted from the air passing through the heat exchanger by means of the fins 46 and being transferred to the water in the pipes 41,42 so that the temperature of the water is increased.

The temperature sensing means 53, which may be in the form of a thermostat set for a predetermined temperature senses the temperature of the water from the outlet pipe 52, and when the predetermined temperature is reached operates, through a control means, the motor 54, to drive the linkage 56 to rotate the flap valve 38 to the position A. Air is then directed through the outlet grill 36 and this prevents the water temperature in the output pipe 52 becoming overheated.

When the temperature indicated by the temperature sensing means 53 falls below a certain predetermined temperature, then it may operate the motor 54 to move the flap valve 38 to position B once again.

In a convenient arrangement, the water from the outlet pipe 52 is fed to a heating system for heating the factory or other buildings adjacent to the fumace in a controlled manner.

Claims

1. A furnace for heat treating articles, air being used as a cooling medium, means being provided to collect said cooling air after it has been heated, and ducting means including moveable valve means adapted so that in a first position it directs the collected air to an outlet means and in a second position it directs the collected air to a heat exchanger, operator means being provided to move said valve means between said first and second positions, the heat exchanger comprising a duct through which the heated air may pass, and means through which a liquid medium passes, heat from the air being transferred to the liquid medium, temperature measuring means being provided to determine if the temperature of the liquid medium is above a predetermined level, said temperature measuring means controlling the operator means which operates the valve means so that when the liquid medium reaches the predetermined temperature the valve is operated to pass the heated air to the outlet means.

2. A furnace as claimed in claim 1 in which the valve means comprises a flap valve in which all of the air is passed to the outlet means when the liquid medium reaches the predetermined temperature.

3. A heat exchanger substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.

4. A furnace substantially as illustrated in Figure 1 incorporating a heat exchanger substantially as ill ustrated in Figure 2.