US2302114A - Pneumatic bell hoist system - Google Patents

Description

Nov. 17, 1942. v G. FOX 2,302,114

PNEUMATIC BELL HOIST SYSTEM Filed June 9, 1941 2 SheetsSheet 1 INVENTOR. G or don Fox Nov. 17, 1942. G. FOX 2,302,114

PNEUMATIC BELL HOIST SYSTEM Filed June 9, 1941 2 Sheets-Sheet 2 Fig. 2

INVENTOR. Gordon Fox Patented Nov. 17, 1942 FFICE PNEUMATIC BELL HOIST SYSTEM Gordon Fox, Chicago, Ill., assignor to Freyn Engineering Company, Chicago, 111., a corporation of Maine Application June 9, 1941, Serial No. 397,231

8 Claims.

The present invention relates to improvements in pneumatic bell hoist systems.

The present invention will be described in connection with bell hoists used for blast furnaces. It is common practice to provide two charging bells at the top of a blast furnace, the bells commonly being coaxially disposed in series along a vertical axis. Said bells are held upwardly against their seats by means of bell hoists. It has been found advantageous in service to operate said hoists pneumatically.

In the event of an explosion between the bells, the lower bell, commonly called the large bell, is forced downwardly from its seat, causing reactions in its corresponding hoist which may prove dangerous.

An object of the present invention is to provide an improved pneumatic bell hoist having relief means whereby to gradually dissipate energy released by an explosion between the bells.

A further object is to provide an improvement in pneumatic bell hoist systems for safely dissipating the energy released by an explosion between the bells of a blast furnace, which improvement is applicable to bell hoists as now used in practice.

A further object is to provide improved relief means for dissipating the energy released by an explosion between the bells of a blast furnace, which relief means are simple, inexpensive and not likely to fail in service.

A further object is to provide improved relief means for dissipating the energy set up by an explosion between the bells of a blast furnace, which relief means are well adapted to commercial service.

Further objects will appear as the description proceeds.

Referring to the drawings Figure 1 is a general view showing a portion of a blast furnace including the bells thereof and bell hoists for controlling the positions of said bells; and

Figure 2 is an enlarged view in section showing the hoist for the large bell of the combination illustrated in Figure 1.

The letter A represents the small bell and the letter 13 represents the large bell of the blast furnace C. Said bells A and B are adapted to cooperate with one another in the charging of the blast furnace C. The two bells A and B are shown as being arranged coaxially in a manner common in practice, the small bell A being controlled by a cable D, while the large bell B is controlled by the cable E. Levers F and G have Ill their extremities connected to said cables D and E, respectively, the other extremities of said levers being connected to the bells A and B, respectively. The cable D for controlling the small bell A is connected to the pneumatic cylinder H, which is adapted to have a reciprocating movement along a vertical axis. The inner wall of said cylinder H has air-tight sliding engagement with a piston I. The upper extremity of the cylinder H is provided with the top cylinder head J and the lower extremity of said cylinder H is provided with the bottom cylinder head K. Said piston I is supported at the top of the stationary column L, within which is disposed the pipe M. Said pipe M is adapted to supply air under pressure to the space between the piston I and the top cylinder head J, said air being supplied to the pipe M from any suitable source of supply (not illustrated). The space surrounding the pipe M and within the column L communicates with the cylinder H below the piston I through the aperture N. Air may be admitted to and exhausted from the space between the column L and the pipe M through the aperture 0 adjacent to the bottom of the column L.

The cable E for controlling the large bell B is connected to the cylinder P, the inner surface of which has air-tight engagement with the piston Q. Said piston Q is supported at the top of the stationary column R, within which is the air supply pipe S. The cylinder P is provided with the top cylinder head T and with the bottom cylinder head U. Said supply pipe S is adapted to conduct air under pressure to or from the space between the piston Q and the top cylinder head T. The column R is provided with the aperture R at the top thereof adjacent to the under side of the piston Q. Said column R is also provided with the aperture V adjacent to the bottom thereof.

Communicating with the interior of the large bell cylinder P adjacent to the top thereof is the check valve W. Communicating with the interior of the large bell cylinder is the relief valve X. Communication to the valves W and X is controlled by the piston Q as the cylinder P moves up and down. The check valve W is adapted to permit the inflow of air to the space between the piston Q and the top cylinder head T (when communication with said valve W is not stopped by the piston Q), but will stop the outflow from said space to the atmosphere. The relief valve X is located part way up the cylinder P in order that there may be some compression of the air trapped below the piston Q to act as a cushion to prevent the cylinder P from lifting to its extreme upper position so quickly that the bottom cylinder head U thereof will strike the piston Q, as will be explained hereinafter.

The mode of operation of the above described embodiment of the present invention is substantially as follows:

Referring to the mode of operation of the cylinder P for controlling the large bell B, it may be stated briefly that when the large bell is to be held in closed position air will be admitted under pressure through the aperture V to exert an air pressure within the cylinder space between the piston Q and the bottom cylinder head U. In practice this pressure may be in the neighborhood of 12 pounds gauge. When it is desired to open the large bell, valve means (not illustrated) will be operated whereby air under pressure will be admitted through the pipe S to the space above the piston Q, and air will be allowed to escape from the space below the piston Q. Under normal operation, when the large bell B is closed and the operating cylinder P is in its lowermost position, if an explosion occurs between the bells A and B the large bell B is forced downwardly, pulling up upon the large bell cylinder P. This action causes compression of the air in the cylinder P below the piston Q and tends to cause a vacuum in the portion of the cylinder P above the piston Q. This action is likely to produce a rebound which may be violent, causing contact between the top cylinder head T and the piston Q.

The relief valve X will preferably be adjusted to open upon the development of pressure in the space below the piston Q a few pounds above the normal operating pressure within said space. The setting of the relief valve X should not be so close to the operating pressure within the space in the lower portion of the cylinder P as to permit too rapid a relief of pressure within this space in the event of an explosion between the bells A and B. In practice, if, as assumed above, the normal operating pressure between the piston Q and the bottom cylinder head U is in the neighborhood of 12 pounds gauge, the valve X may be set to cause relief upon the development of approximately 20 pounds gauge.

The check valve W is operative at the same time to permit some outside air to be drawn into the region between the piston Q and the top cylinder head T to prevent the creation of a vacuum at that point, thus serving further to prevent a rebound of the cylinder P.

By reason of the fact that the relief valve X is located a considerable distance above the bottom cylinder head U, the result is had that a considerable portion of the air in the lower part of the cylinder P is trapped, causing it to be further compressed to enable it to act as an air cushion, thereby preventing the bottom cylinder head U from striking the piston Q. Any air admitted through the check valve W to the space above the piston Q will be exhausted through the pipe S when the cylinder P is returned to its lowermost position illustrated in Figure 2.

Though a' preferred embodiment of the present invention has been described in detail, many modifications will occur to those skilled in the art. It is intended to cover all such modifications that fall within the scope of the appended claims.

What is claimed is- 1. In a blast furnace, in combination, a pair of charging bells arranged in series with one another, means for holding said bells upwardly in closed positions, said means for holding the innermost of said bells including a movable cylinder adapted to reciprocate in a vertical direction upon a piston, said cylinder having top and bottom cylinder heads, means for delivering air to and discharging air from the space between said piston and said top cylinder head, means for delivering air to and discharging air from the space between said piston and said bottom cylinder head, a check valve controlled by said piston for admitting air to the space between said piston and said top cylinder head, and a relief valve controlled by said piston for discharging air from the space between said piston and said bottom cylinder head.

2. In a blast furnace, in combination, a pair of charging bells arranged in series with one another, means for holding said bells upwardly in closed positions, said means for holding the innermost of said bells including a movable cylinder adapted to reciprocate in a vertical direction upon a piston, said cylinder having top and bottom cylinder heads, means for delivering air to and discharging air from the space between said piston and said top cylinder head, means for delivering air to and discharging air from the space between said piston and said bottom cylinder head, a check valve controlled by said piston for admitting air to the space between said piston and said top cylinder head, and a relief valve controlled by said piston for discharging air from the space between said piston and said bottom cylinder head, said relief valve having communication with the interior of said cylinder at a position at which said piston will cut off access to said relief valve when said bottom cylinder head has travelled upwardly from its lowermost position throughout a portion of the distance from said lowermost position to the lowermost extremity of said piston.

3. A hoist suitable for holding up the lowermost bell of a setof blast furnace charging bells including a column provided with a piston, a reciprocable cylinder having air-tight relationship with said piston, said cylinder having top and bottom cylinder heads, said column being provided with means for delivering air to and exhausting air from the space between said piston and said top cylinder head, said column also being provided with means for delivering air to and exhausting air from the space between said piston and said bottom cylinder head, a check valve for admitting the air from the atmosphere to the space between said piston and said top cylinder head, and a relief valve for providing communi cation between the atmosphere and the space between said piston and said bottom cylinder head.

4. A hoist suitable for holding up the lowermost bell of a set of blast furnace charging bells including a column provided with a piston, a reciprocable cylinder having air-tight relationship with said piston, said cylinder having top and bottom cylinder heads, said column being provided with means for delivering air to and exhausting air from the space between said piston and said top cylinder head, said column also being provided with means for delivering air to and exhausting air from the space between said piston and said bottom cylinder head, a check valve for admitting the air from the atmosphere to the space between said piston and said top cylinder head, and a relief valve for providing communication between the atmosphere and the space between said piston and said bottom cylinder head, said relief valve being positioned intermediate of the distance between the lowermost position of said bottom cylinder head and said piston, said piston being adapted to shut off communication between the interior of said cylinder and said valves during the movement of said cylinder. v

5. An operating hoist for holding the lower charging bell of a blast furnace up against its seat, comprising a weighted cylinder, a column provided with a piston having air-tight relationship with the interior of said cylinder, and top and bottom cylinder heads for said cylinder, said column being provided with means for alternatively communicating pressure upon the two sides of said piston to cause the raising and lowering of said cylinder relative to said piston, a check valve controlled by said piston for admitting air from the atmosphere to the space between said piston and said top cylinder head and a relief valve controlled by said piston for providing communication between the atmosphere and the space between said piston and said bottom cylinder head.

6. An operating hoist for holding the lower charging bell of a blast furnace up against its seat, comprising a weighted cylinder, a column provided with a piston having air-tight relationship with the interior of said cylinder, and top and bottom cylinder heads for said cylinder, said column being provided with means for alternatively communicating pressure upon the two sides of said piston to cause the raising and lowering'of said cylinder relative to said piston, a check valve controlled by said piston for admitting air from the atmosphere to the space between said piston and said top cylinder head, and a relief valve controlled by said piston for providing communication between the atmosphere and the space between said piston and said bottom cylinder head, said relief valve being positioned intermediate of the distance between the lowermost position of said bottom cylinder head and said piston, said piston being adapted to shut off communication between the interior of said cylinder and said valves during the movement of said cylinder.

7. In a blast furnace, in combination, a pair of charging bells arranged in series with one another, means for holding each of said bells upwardly in closed position, said means for holding the innermost of said bells including a piston and a cylinder interfitting with said piston, said piston and said cylinder being relatively movable, means for admitting air under pressure alternatively to the two sides of said piston for causing such relative movement, a check valve adapted to permit inflow of air to the space within said cylinder on one side of said piston, and a relief valve to permit the passage of air between the atmosphere and the space within said cylinder upon the other side of said piston, said. Valves being controllable by said piston.

8. In a blast furnace, in combination, a pair of charging bells arranged in series with one another, means for holding each of said bells upwardly in closed position, said means for holding the innermost of said bells including a piston and a cylinder interfitting with said piston, said piston and said cylinder being relatively movable, means for admitting air under pressure alternatively to the two sides of said piston for causing such relative movement, a check valve adapted to permit inflow of air to the space within said cylinder on one side of said piston, and a relief valve to permit the passage of air between the atmosphere and the space within said cylinder upon the other side of said piston, said valves being controllable by said piston, said last mentioned valve being located in a position to be shut off by said piston after bell opening relative movement of said piston and cylinder equal to a material portion of the possible rela tive movement between said piston and said cylinder.

GORDON FOX.

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