Patent Application
20060049641
The disclosure relates to an improved oven door latch mechanism and more particularly to a rotary wedge latch system for sealing an oven door during a coking operation.
Coke oven doors for horizontal coke ovens have been a source of air leakage during the coking cycles. Each horizontal coke oven has two doors. One door is located on a coal charging side of the oven and a second door is located on a coke discharge side of the oven. Each of the doors is made of a combination of refractory and metal and is very large and heavy. The doors are required to close the oven to maintain the heat inside the coke ovens which may range from about 1000° to about 1500° C., and to maintain a negative pressure inside the oven. A negative pressure is required to move flue gases and combustion products away from the coke bed in the oven.
Since the ovens operate under a negative pressure, it is important that both the charging door and the coke discharge door remain closed as tightly as possible, and that the doors remain tightly closed throughout the coking cycle. A tightly closed door means that the door is held tightly against the oven door jamb, lintel, and sill plate. Loose doors allow excessive air infiltration which can result in poor product quality or low product yields. Excess air entering the oven can come in contact with very hot coke (1000+° C.). Once contact is made, the air bums the coke product thereby reducing its value and leading to product yield loss.
Conventional door latches used to maintain the doors in a closed relationship with the coke ovens consist of cam latches that are manually adjusted. The cam latches engage a backside of a front flange of a beam which is disposed on each side of the oven door. There are typically four cam latches per door.
Door latch closing requires that a worker apply force to a wrench that is used to rotate and tighten the cam latches. Such force may lead to back strains and other injuries. Furthermore, a worker can apply only about 600 kilograms of force to each cam latch. This amount of force may not be sufficient to overcome slight irregularities, such as warping, bending, and solids buildup, of either the door frame or the door jamb. Accordingly, the doors may not be closed as tightly as necessary to reduce or prevent excess air infiltration into the oven.
During a 48 hour coking cycle there are small movements of the oven relative to the door. These movements are a result of differential thermal expansion. Such movements have a tendency to make the cam latches rotate slightly and become loose. Typically about 25 to 50 percent of the cam latches become loose during a coking cycle. Accordingly, significant manpower is required to monitor and adjust the cam latches for efficient coke oven operation.
Accordingly, there is a need for a door latch system that is less prone to movement or loosening and that can be positioned automatically rather than manually during an oven door closing operation.
With regard to the above and other needs and objective, there is provided, in one embodiment, an oven door latch system for a coke oven door positionable within an oven door opening and method of sealing a coke oven. The door latch system includes a rotary member rotatively attachable to the oven door. The rotary member has a wedge-shaped, arcuate engagement edge for variably engaging a striker plate on a buck stay member adjacent the oven door opening when the oven door is disposed in the opening of the oven. A tab member is also included on the rotary member. A remotely operated adjustment actuator is provided for engaging the tab member to rotate the rotary member in conjunction with an oven door opening or closing operation. Enhanced oven door sealing is provided by the rotary wedge latch system.
In another embodiment there is provided a method for reducing air leakage through a door opening of a coke oven when a coke oven door is disposed in the door opening to close the door opening. The method includes providing an oven door latch system for a coke oven door. The door latch system contains a rotary member rotatively attached to the oven door. The rotary member has a wedge-shaped, arcuate engagement edge for variably engaging a striker plate on a buck stay member adjacent the oven door opening when the oven door is disposed in the opening of the oven. The rotary member also includes a tab member thereon for moving the rotary member from an engaged position adjacent the striker plate to a non-engaged position remote from the striker plate. A remotely operated adjustment actuator is provided for moving the rotary member from the engaged position to the non-engaged position. During a door closing operation, the coke oven door is disposed in the door opening. The adjustment actuator is engaged with the rotary member. As the adjustment actuator is actuated, the actuator rotates the rotary member so that an increasing wedge portion of the rotary member is engaged with the striker plate of the buck stay adjacent the oven door.
In yet another embodiment there is provided an oven door latching mechanism for sealing an oven door of a furnace. The mechanism includes rotary wedge means attached to the oven door for variably engaging a striker plate of an oven buck stay. Also includes is actuator means remote from the oven door for rotating the rotary wedge means from an engaged position adjacent the striker plate to a non-engaged position remote from the striker plate.
An important advantage of the mechanism and method described herein is that the rotary wedge member is substantially self-adjusting once the wedge member is engaged with the striker plate of the oven buck stay. The self-adjustment feature of the latch system means that the latches do not loosen during oven heating cycles thereby reducing air leakage into the oven. In fact, movement of the latches, if any, tends toward increased door sealing.
Another advantage of the system is that the door latches can be positioned using a relatively simple adjustment mechanism rather than manpower force to seal an oven door. The system may thus lead to a reduction in back strain injuries and a reduction in manpower required to operate the ovens. Furthermore, each of the rotary wedge members on an oven door provide independent door sealing force for sealing an oven door even if the oven door is cocked.
Further advantages of the disclosed embodiments will become apparent by reference to the detailed description of preferred embodiments when considered in conjunction with the following drawings illustrating one or more non-limiting aspects of the embodiments, wherein like reference characters designate like or similar elements throughout the several drawings as follows:
Coke ovens, particularly non-recovery coke ovens, are typically provided in a battery of ovens in a coke plant. A coking cycle for each of the ovens is about 48 hours depending on the size of the ovens. Accordingly, there is periodic discharging of coke from an oven and charging coal to the oven. Mechanical devices have been devised for charging coal and discharging coke from the ovens. The devices include mechanisms for removing and replacing the oven doors of a horizontal coking oven during the charging and discharging operations. A general description of such devices and coke oven operation is contained in U.S. Pat. No. 5,447,606 to Pruitt, the disclosure of which is incorporated herein by reference.
As indicated above, oven doors are removed during coal charging and coke discharging operations. A typical oven door contains a plurality of latches for sealing the oven door. However, conventional latches fail to be self-adjusting, and in many instances, require constant adjustment due to loosening. Accordingly, an improved oven door latch system is provided.
As shown in
The oven door 10 is preferably a door made of steel and having a refractory material 16 applied to an oven side of the door. During an oven door removal and replacement operation, a utility car is positioned adjacent the door 10 to lift the door 10 out of an oven opening using lifting tabs 18. Stop members 22 are fixedly attached to the oven door 10, as by welding, to prevent the latches 12 from rotating and engaging structural oven members such as buck stays. Accordingly, for each latch 12 there is a corresponding stop member 22.
A preferred rotary wedge latch 12 according to embodiments described herein is illustrated in detail in
The arcuate edge 24 has a length sufficient to gradually engage the striker plate 26 upon movement of the oven door 10 during expansion and contraction thereof due to atmospheric condition changes and oven temperature changes. Accordingly, the edge 24 may preferably have an arcuate length ranging from about 80 to about 180 degrees, most preferably about 120 degrees providing the edge 24 with a slope ranging from about 0.04 to about 0.10 millimeters per millimeter arcuate length. The overall length of the arcuate edge 24 may preferably range from about 40 to about 100 centimeters or more.
Also included on the latch 12 is a tab member 34 for use in rotating the latch 12 from a position as shown in
With reference to
As shown in sequence in
An actuator mechanism 64 for rotating the latch 12 is illustrated in
A detail of the lever member 68 is shown in
During a coke oven charging operation, a pushing and charging machine is disposed adjacent a charging door and a utility car is disposed adjacent a coke discharge door of the oven. Both doors are removed from the oven and the coke is pushed out of the oven by a ram on the pushing and charging machine. Once the coke is removed from the oven, the coke discharge door is secured to the coke discharge side of the oven. Coal is then charged into the oven through the charging side of the oven. Once the oven is charged with coal, the charge door is secured to the oven. After the coking cycle is complete, the discharging and charging process is repeated.
When a utility car or pushing and charging machine containing the actuator mechanism 64 is adjacent the door 10 of an oven, to place or seat the door in a door jamb of the oven, a door lift mechanism exerts pressure on the door 10 thereby slightly deforming the oven opening. As the oven opening is deformed, the actuator mechanism 64 is activated to rotate the latches 12 into the second position shown in
Likewise, when removing a door 10 from the oven opening, pressure is applied to the door 10 by the pushing and charging machine or utility car thereby decreasing the pressure of the striker plate 26 on edge 24 of the latches 12. As before, very little force is needed to rotate the latches 12 using the actuator mechanism 64 when the door 10 is forced in the door jamb of the oven.
Yet another actuator mechanism 90 that may be used to engage the tab member 34 for rotating the latch 12 is illustrated in
It is contemplated, and will be apparent to those skilled in the art from the preceding description and the accompanying drawings, that modifications and changes may be made in the embodiments described herein. Accordingly, it is expressly intended that the foregoing description and the accompanying drawings are illustrative of preferred embodiments only, not limiting thereto, and that the true spirit and scope of the present embodiments be determined by reference to the appended claims.
