US2669070A - Lehr - Google Patents

Description

Feb. 16, 1954 v 1 c w K G 2,669,070

LEHR I Filed April 14, 1951 CONS TANT/NE n: KULIG M ATTORNEYS suitable blower, such as is shown mounted on the top of the firebox section (Fig. 1), may be provided at the top of the up-takes for the necessary draft to draw the gases from the chamber '5 and for regulating the portions of heat distributed to the opposite sides of the tunnel.

The combustion chamber I is enclosed both above and below and at its ends with highly conductive tile which provides for a maximum transfer of heat directly to the air in the tunnel 4 and to air in a passageway ll beneath the tiles l0.

Air is supplied to the passageway II and to a belt preheater l2 from a pair of downcomers l3 and 14 which are disposed about the uptakes 8 and 9, respectively. The heated air in the passageway H is directed upwardly through a vertical passageway :5 into the front end of the tunnel 4.

The belt warmer l2 beneath the firebox I provides an enclosed passageway 56 through which the endless belt conveyor 5- returns to the front end of the lehr and into which the air from the downcomers l3 and I4 is discharged in predetermined amounts regulated by a damper IT. The damper H is automatically preset by suitable linkage, generally designated I8, which connects the damper with an air motor l9 that operates in response to changes in temperature of a thermostatic element located at the top and adjacent the front end of the tunnel '4.

As shown in Fig. 1, the linkage 18 includes a connecting rod IBabetween the motor l9 and an arm 2m of a bell crank 21 another arm 21b of which is connected by rod 22 with a crank 23 secured to a shaft 24 on which the damper i1- is mounted.

A recirculating blower or similar device B withdraws and directs air from the rear end of the annealing or slow cooling zone of the tunnel through ducts or flues l3a and Ma to the downcomers l3 and M, respectively, for introduction into the belt preheater I2 and reintroduction into the tunnel at the front of the firebox section through the passages II and I5.

As shown in the drawings, the flues [3a and [4a are each provided with a damper 25 for throttling the rate at which air is withdrawn from the tunnel and discharged into the downcomers l3 and I4. Both dampers 25 are secured to a rotat-' able shaft 26 which extends transversely through the lehr and which has secured to an end thereof a crank 27 by means of which the positions of the dampers are adjusted automatically between the relatively closed or throttled position shown in dotted line in Fig. 3 and the more open position shown in phantom.

The crank 21 normally is maintained by a spring 28 against an adjustable stop 29 which limits clockwise movement of the crank and determines the normal throttled positions of the dampers '25. As shown in Fig. 3, the stop 29 is slotted as at 29a and provided with a fastener 29?) by means of which the position of the stop 29 may be adjusted in conventional manner; Opening of the dampers is effected by thebell crank 2| to an arm 2lc of which is connected a rod 30 having an adjustable lost motion connection with the crank 2'5. The lost motion con nection is provided with an ear 21a of the crank 21 through which the rod 30 slidably extends,

the ear 2'! being engageable by nuts 3! to pivot the crank 21 counterclockwise to further open the dampers 25 whenever the bell crank 2| pivots sufliciently in the clockwise direction in response iii) to increase in the temperature of the thermostat 20 which is located just inside the front entrance.

The temperature in the firebox portion of the tunnel is primarily controlled by a thermostat 32 which regulates the burner 6.

In accordance with the present invention, the amount of air returned through the ducts l3a and hid is regulated automatically by the dampers 25 which are adjusted in direct response to changes in the temperature of the thermostat 2i) and indirectly in response to indraft or outdraft at the entrance to the lehr. The tendency for outdraft at the lehr entrance is caused by increased forward drift which increases the temperature of the thermostat 20. Indraft at the lehr entrance is caused by backward drift which brings cold air into the tunnel entrance and lowers the temperature of the thermostat 20. The front entrance control also responds indirectly to load changes. These responses are as follows: with light load or an empty lehr, the temperature at 20 is low so that the dampers l1 and 25 are automatically adjusted by the motor is to return a minimum volume of air through the ducts lta and Ma virtually all of which is reheated in the passage II and reintroduced into the tunnel. With light to moderate loads, the damper 25 is not moved and the volume" of air Withdrawn from the tunnel remains minimal, but a lesser portion is reheated in the space H, the damper i7 automatically being moved to direct a greater portion. into the belt preheater l2. With moderate to heavy loads, as, for example, above 350 oz. per minute in a 64ft. x 5 ft. wide lehr, the dampers 25 are opened further and the returned air volume is increased to a maximum'virtually all of which is diverted to the belt'preheater I2.

These provisions insure adequate heat for the annealing zone, minimum loss through heating of excess air, maximum cooling capacity, and maximum heat recovery through belt preheating and recirculation.

The maximum backward drift occurs in the tunnel 4 when the lehr is empty. This drift is a flow of air in definite amount from the conditioning zone to the rear of the slow cooling zone which cools and gives up the amount of heat needed to balance wall losses.

In order to maintain a neutral flow at the front door with an empty lehr, the amount of heated, air returned through the ducts I3a and Ma for recirculating is just sufficient to effect the necessary backward drift from the conditioning to the slow cooling zone while maintaining a neutral drift or flow at the entrance to the tunnel and beyond the slow cooling zone.

With a light load of glass, the required backward drift in the slow cooling zone diminishes, but the ducts l3a and Ma continue to return the same volume of heated air. However, the thermostat 20 operates to divert some of the air to the belt preheater [2 so that the air heated in the passage H under the firebox l is only that necessary to supply the diminished tunnel drift and keep a neutral drift at the front door. The amount of air used for belt heating is supplied by forward driftfrom beyond the slow cooling zone to the blower B and in effect heat supplied to the belt preheater is that recovered from air from the rapid cooling zone.

With'a fairly heavy load, the tunnel drift becomes all forward and the thermostat 2D acts to adjust the damper I1 '50 that a maximun'i amount of returned air is directed into the belt preheater l2 and a minimum amount is heated in the chamber I l and reintroduced into the tunnel. Simultaneously, in accordance with the invention, the thermostat and its associated motor l9 act through rod 30 and its lost motion connection with the crank 21 to adjust the dampers 25 to their maximum open positions so that the amount of air returned through the ducts Na and Ma is increased to a maximum.

Having thus described my invention, I claim:

1. In a glassware annealing tunnel lehr having a heating and conditioning section and a cooling section which provide conditioning and cooling zones of the tunnel through which ware is transported, means for withdrawing atmosphere from the cooling zone of said tunnel and directing the withdrawn atmosphere to the conditioning section of the lehr, means for dividing said withdrawn atmosphere and reintroducing a portion only of the withdrawn atmosphere into the conditioning zone of the tunnel, and discharging another portion out of the lehr, and means for automaticallyregulating the quantity of withdrawn atmosphere, said regulating means being responsive to lehr temperature in the conditioning zone.

2. In a glassware annealing tunnel lehr having a heating and conditioning section and a cooling section which provide conditioning and cooling zones of the tunnel through which ware is transported, means for withdrawing atmosphere from the cooling zone of said tunnel and directing the withdrawn atmosphere to the conditioning section of the lehr, means for dividing said withdrawn atmosphere and reintroducing a portion only of the withdrawn atmosphere into the conditioning zone of the tunnel and discharg ing another portion out of the lehr, means for regulating the quantity of atmosphere withdrawn,

means for regulating the portion of withdrawn atmosphere reintroduced into the conditioning zone of the tunnel relative to said portion discharged from the lehr, and thermostatic means responsive to lehr temperature in the conditioning zone for automatically adjusting both of said regulating means.

3. In a glassware annealing tunnel lehr having a heating and conditioning section and a cooling section which provide conditioning and cooling zones of the tunnel through which ware is transported on an endless belt conveyor, a warmer'for heating the belt outside of the tunnel, means for withdrawing atmosphere from the cooling zone of said tunnel and directing the withdrawn atmosphere to the conditioning section of the lehr, means for dividing said withdrawn atmosphere and directing a portion of said withdrawn atmosphere into the belt warmer and another portion of said withdrawn atmosphere into the conditioning zone within the tunnel, damper means for regulating the quantity of air Withdrawn, damper means for regulating the proportion of returned atmosphere discharged into the conditioning zone of the tunnel and into the belt warmer independently of the quantity regulating damper means, and thermostatic means responsive to the temperature of the atmosphere in the conditioning zone for automatically adjusting said damper means.

CONSTAN'IINE W. KULIG.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,783,208 Williams Dec. 2, 1930 2,275,263 Merrill Mar. 3, 1942 2,507,673 Merrill May 16, 1950

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