US3061314A

US3061314A - Blast furnace bell rod gas seal

Info

Publication number: US3061314A
Application number: US9044A
Authority: US
Inventors: James S Miller
Original assignee: Armco Inc
Current assignee: Armco Inc
Priority date: 1960-02-16
Filing date: 1960-02-16
Publication date: 1962-10-30
Anticipated expiration: 1979-10-30

Description

Oct. 39, 1962 5, 3,061,314

BLAST FURNACE BELL ROD GAS SEAL Filed Feb. 16, 1960 INVENTOR. \/,4M$ 5. Mae-z,

Y WARM ATTORNEYS.

United States Patent Ofifice 3,061,314 Patented Oct. 30., 1962' Ohio Filed Feb. 16, 1960, Ser. No. 9,044 6 Claims. (Cl. 2773) This invention relates to a blast furnace bell rod gas seal. The conventional blast furnace is provided at the top with a large bell which has the appearance of an inverted cone and which is manipulated by means of a rod extending vertically upward. This bell in its raised position is closed and when lowered by means of its rod permits the charge resting on the upper surface of the bell to be disposed into the blast furnace.

Disposed above the large bell there is a small bell which is similar to the large bell and is manipulated by means of a small bell rod in the form of a sleeve through which the large bell rod passes. Means are provided to raise the small bell to close it and to lower the small bell to deposit a charge on the upper surface of the large bell. Means are also usually provided for periodically rotating the small bell a fraction of a circle so as to insure that the charge from the small bell are uniformly distributed over the large bell.

When the large bell is open during a charging operation or if it is not seated perfectly, the furnace gas pressure can cause the blast furnace gas to blow out through the annular space between the large and small bell rods. If the furnace is being operated at high top pressure, this is not only unpleasant but damaging to equipment. This gas contains high abrasive 'dust and causes considerable abrasion of the bell rods. Abrasion of the seat for the large bell is also caused so that after some time the large bell can no longer seat perfectly to close the furnace.

With the foregoing considerations in mind, it is the principal object of the present invention to provide a seal to prevent the escape of blast furnace gas between the large and small bell rods so that when the small bell is seated no gas will blow past the large bell seat. In this way, the life of the large bell and its hopper and of the bell rods is greatly increased.

In the raising and lowering of the large and small bell rods, these rods do not maintain at all times a concentric relationship in that the large bell rod may occupy various positions off-center of the sleeve-like small bell rod.

It is therefore a further object of the invention to pro-' vide a seal which will permit relative movement between the large and small bell rods in directions perpendicular to the axes thereof.

It is a further object of the invention to charge the seal with grease under pressure slightly above the furnace top pressure and to provide means for automatically maintjaining the grease pressure in the seal. I

These and other objects of the invention which will be described in more detail hereinafter I accomplish by that certain construction and arrangement of parts of which I shall now describe an exemplaryembodiment.

Reference is made to the drawing forming a part hereof and in which:

FIGURE 1 is a simplified cross-sectional view through the upper portion of a blast furnace showing the relative positions of the large and small bells and the location of the seal which forms the object of the present invention.

FIGURE 2 is a greatly enlarged view partly in crosssection showing the seal proper.

FIGURE 3 is a plan View as seen from the top of FIG- URE 2 and 3 FIGURE 4 is a hydraulic diagram showing -the-arrange-- ment for maintaining the desired pressure relationshipsi Briefly, in the practice of the invention I provide a seal between the small bell rod and the large bell rod, which seal comprises a pair of telescoping cup-like elements sealed against each other, one of which is arranged to rotate with the small bell rod and the other of which is arranged to remain non-rotatable with the large bell rod. Within the chamber constituted by these telescoping cuplike members, I provide a packing gland to seal against the large bell rod and capable of moving laterally with the large bell rod and sealed against the walls of the seal chamber.

Hold-down cylinders are provided to compress the packing; and hydraulic fluid from a high pressure source is supplied at intermediate pressure to the hold-down cylinders and at low pressure (slightly above furnace top pressure) to the seal chamber. Grease is fed to the cylinder and chamber periodically and means are provided to maintain the desired pressure relationships.

Referring in greater detail to FIGURE 1 of the drawing, the blast furnace top is indicated at 10'. Within the top of the blast furnace is the large bell hopper 11 and the large bell 12 cooperates with the hopper 11. The large bell 12 is raised and lowered by the bell rod 13.

Above the large bell there is the small bell hopper 14 with which the small bell 15 cooperates. The small bell 15 is secured to the small bell rod 16 which is in the form of a sleeve by means of which the small bell cani be raised and lowered. The small bell and hopper are charged by means of the conventional skip car 17 which dumps its charge through the hopper 18 onto the small bell 15. The small bell is then given a certain amount of rotation by conventional means (not shown) and the bell 15 is then lowered whereby the contents of the hopper 14 are discharged into the hopper 11 and onto the large bell 12.

This sequence of events is repeated until the hopper 11 and large bell 12 are fullycharged and then, while the small bell 15 is closed; the large bell 12 is lowered to discharge its contents into the blast furnace. It will be clear that while the large bell 12 is in lowered position. the furnace gases can issue through the hopper 11 and through the small bell 15 and the space between the

bell rods

13 and 16 thereby causing the damage described above. V r

The

bell rods

13 and 16 are manipulatedby mechanism including the

pivoted levers

19 and 20 respectively. The seal which constitutes the object of the present invention is located in a region indicated at S in FIGURE 1.

Referring now to FIGURE 2 which more clearly shows the details of the seal, the seal comprises a lower cup member 21 suitably secured to the small bell rod 16 as by welding. Therefore, the entire seal will be raised and loweredwith the bell rod 16'and will be rotated when the small bell is rotated. l

An inverted or upper cup-like member 22 is disposed in telescoping relationship with the cup-like'member'zl and is provided with the central bore 23 providing clearance for the expected lateral movement of thebe'll 13 with respect to the bell rod 16. The lower cup member 21 also has a centralbore 24 similarly providing clearance for the bell rod 13.

Within the chamber 25 constituted by the cup members 21 and 22, there is provided a packing gland. This pack? ing land comprises the mutually telescoping

members

26 and 27 between which a packing material 28 is arranged to be compressed, as is well known in seal practice. 5 If the

members

26 and 27 are telescoped together the pack ing 28 is compressed so as to expand laterally and seal against the rod 13. The

assembly

26, 27,28 thus movesv as a unit with the bell rod 13 during its lateral movement."

The member'26 is sealedagainst the cup memberzl' by a seal 29 and the member -27 is sealed against the cup-22 u by a seal 30. The telescoping cup members 21 and 22 are sealed by a seal 31. It will now be clear that axial movement of the rod 13 with respect to the seal, as will occur when either of the bells is raised or lowered, is sealed by the packing 28 and that lateral movement of the rod 13 with respect to the rod 16 is sealed by the seals 29 and 30, and that relative telescoping movement between the cup members 21 and 22 as produced by the hold-down cylinders, which will be described hereinafter, is sealed by the seal 31.

The cup member 22 is formed with the outwardly extending flange 32 which is provided with suitable apertures 33 for the passage of the hanger rods 34. These hanger rods are suitably secured as by bolting to a plate 35 (FIG. 4) which contains a thrust bearing 36 cooperating with the flange 37 on the rod 16. Thus, the plate 35 and hanger rods 34 support the bell rod 16 against the pull of gravity but permit the bell rod 16 to rotate with the thrust being taken by the flange 37 on the hearing 36. The engagement of the hanger rod 34 by the apertures 33 prevents the flange 32 and the upper cup member 22 from rotating but permits vertical movement thereof.

The upper cup member is held down and urged toward the lower cup member by a movement of hold-down cylinders 38, each having a piston rod 39 secured to the flange 32. It will be clear that pressure applied to the upper side of the pistons within the cylinders 38 will urge the cups 21 and 22 together so as to compress the packing 28.

The seal chamber 25 is charged with grease at a pressure slightly above the blast furnace top pressure. If the blast furnace is maintained at p.s.i., the pressure in the chamber may be maintained at 12 p.s.i. for example. The hold-down cylinders 38 are maintained at a pressure of 120 p.s.i. for example. In FIGURE 4 there is shown a hydraulic circuit for maintaining the relationship between the 12 p.s.i. and 120 p.s.i. and for charging the sys tem when necessary.

It will be seen that a proportioning cylinder and piston is generally indicated at 40. This cylinder has a larger portion 41 and a smaller portion 42 and a two-part piston having the large area portion 43 within the cylinder 31 and the small area portion 44 within the cylinder 42. It will be understood that if the relationship of pressures to be maintained is 12 p.s.i. and 120 p.s.i. as described above, the area of the piston 43 will be ten times the area of the piston 44.

The cylinder 41 is connected through a line 45 to the seal chamber 25 and the cylinder 42 is connected through a

line

46, 47, 48 to the hold-down cylinders. In other words, the small area piston 44 supplies the hold-down cylinders at intermediate pressure (120 p.s.i.) and the large area piston supplies the seal chamber 25 at low pressure (12 p.s.i.).

A by-pass 49 is provided around the cylinder 40 and in this by-pass there is disposed a normally closed valve 50. The piston 44 has connected to it a rod 51 adapted to actuate the valve to open it and when the system is in balance the piston is in the position shown in FIG- URE 4, closing the valve 50.

A pressure cylinder 52 is provided having therein a piston 53 urged downwardly by a spring 54 and having a rod 55. The cylinder 52 is connected into the line 46--47 as shown and an associate line 56 is also connected into the line 47-48 and is provided with a normally closed valve 57. A line 58 is connected into the

line

46, 47 to supply grease to the system at high pressure (say 3,000 p.s.i.).

The operation of the system will now be clear. If 12 p.s.i. is maintained in the seal chamber 25 and 120 p.s.i. in the hold-down cylinders 38, the various valves and pistons are in the position shown. The automatic furnace lubrication system supplies A cubic inch of grease, for example, through the line 58 once an hour. If all requirements are satisfied, the grease passes into the cylin- 4 der 52 raising the piston 53 so that its rod 55 actuates the valve 57 to open it so that excess grease may be exhausted through the line 47, valve 57 and line 56. Grease will be discharged to exhaust'until the piston 53 returns to its normal position closing the valve 57.

If the pressure in the seal chamber 25 drops, the

piston

43, 44 moves upwardly to reestablish the balance. As it moves upwardly, the rod 51 moves upwardly and permits the valve 50 to open whereupon grease in the cylinder 52 may pass through the

line

46, 49 and 45 to recharge the seal. As soon as the seal pressure is reestablished, the pressure, instead of passing through the line 45, is applied to the line 59 into cylinder 41, whereby the

piston

43, 44 is returned to its normal position closing the valve 50.

If pressure is lost in the hold-down cylinders 38, the piston 53 can supply grease through the

lines

47 and 48 to replenish them.

From the foregoing description, it will be seen that I have provided a seal which will prevent damage to the large bell and its seat as well as to the large and small bell rods, and that I have provided means for maintaining the seal under pressure with an automatic hydraulic system. It will be clear that various modifications may be made without departing from the spirit of the invention and I therefore do not intend to limit myself otherwise than as set forth in the claims which follow.

Having now fully described the invention, what I claim as new and desire to secure by Letters Patent is:

l. A seal for sealing a shaft with respect to a sleeve and the like, wherein said shaft and sleeve have relative axial, rotational and radial movement with respect to each other, comprising a first element secured to said sleeve, to rotate and reciprocate therewith, a second element in telescoping and sealing engagement with said first element and fixed against rotation, said elements together constituting a seal chamber, and a shaft seal within said chamber in sealing engagement with said shaft and in sealing engagement with each of said first and second elements for relative movement with respect to said elements when relative radial movement occurs between said shaft and sleeve.

2. A seal according to claim 1, including means for compressing said first and second elements together, and means for maintaining in said seal chamber a supply of grease under pressure slightly greater than the pressure existing between said shaft and sleeve outside said chamber.

3. A seal according to claim 2, wherein said first means includes a hold-down cylinder having a piston for compressing said seal externally, and said second means comprises a pressure system for supplying grease to the said chamber and to said hold-down cylinder, means for proportioning the pressure at which grease is supplied to said hold-down cylinder and said chamber, and means for -by-passing said hold-down cylinder and said chamber when predetermined pressures exist in said hold-down cylinder and chamber.

4. A seal according to claim 3, wherein said second means comprises a pressure proportioning cylinder and piston having a relatively large area piston within a larger portion of said cylinder and an integral relatively small area piston within a smaller portion of said cylinder, the areas of said pistons being in inverse ratio to the pressures to be maintained in said chamber and hold-down cylinder, a line connecting the larger portion of said proportioning cylinder to said chamber, a line connecting the smaller portion of said proportioning cylinder to said hold-down cylinder, a by-pass around said proportioning cylinder, a normally open valve in said by-pass, means secured to the small area portion of said proportioning piston and adapted to hold said valve in the closed position when the correct pressure relationship exists between said chamber and hold-down cylinder, an exhaust line connected into the line leading to said hold-down cylinder, a normally closed valve in said exhaust line, a pressure cylinder having a piston and spring system, said last named piston having means to open said normally closed valve when the pressure requirements of the seal are satisfied, a line connecting said pressure cylinder into the line leading to said hold-down cylinder, and a line connecting the line leading to said hold-down cylinder to a source of grease under high pressure.

5. A seal for sealing a shaft with respect to a sleeve and the like, wherein said shaft and sleeve have relative axial, rotational and radial movement with respect to each other, comprising a first cup member secured to said sleeve to rotate .therewith, a second cup member inverted with respect to said first cup member and in telescoping relation therewith, and providing, together with said first cup member, a seal chamber, means for holding said second cup member against rotation, said cup members having central apertures for the passage of said shaft therethrough with clearance thereabout, sealing means between the telescoping surfaces of said cup members, a packing gland comprising two telescoping annular elements disposed within said telescoping cup members and adapted to compress an annular packing between them and against the shaft, sealing means between each of said telescoping annular elements and the respective first and second cup members, means for supplying grease, under a pressure slightly above the pressure existing between said shaft and sleeve outside said chamber, into said chamber, hydraulic means for pressing said telescoping cup members toward each other, and means for maintaining the pressure in said chamber and in said hydraulic means.

6. A seal according to claim 5, wherein said hydraulic means includes a hold-down cylinder having a piston connected to said second cup member, a pressure proportioning cylinder and piston having :a relatively large area piston within a large portion of said cylinder and an integral relatively small area piston within a smaller portion of said cylinder, the areas of said pistons being in inverse ratio to the pressures to be maintained in said seal chamber and hold-down cylinder, a line connecting the larger portion of said proportioning cylinder to said seal chamber, a line connecting the smaller portion of said proportioning cylinder to said hold-down cylinder, a bypass around said proportioning cylinder, a normally open valve in said by-pass, means secured to the small area portion of said proportioning piston and adapted to hold said valve in closed position when the correct pressure relationship exists between said seal chamber and holddown cylinder, an exhaust line connected into the line leading to said hold-down cylinder, a normally closed valve in said exhaust line, a pressure cylinder having a piston and spring therein, said last named piston having means to open said normally closed valve when the pressure requirements of the seal are satisfied, a line connecting said pressure cylinder into the line leading to said hold-down cylinder, and a line connecting the line leading to said hold-down cylinder to a source of grease under high pressure.

References Cited in the file of this patent UNITED STATES PATENTS 1,078,784 Grisham Nov. '18, 1913 2,408,945 Mohr et a1. Oct. 8, 1946 2,758,674 Day Aug. 14, 1956 2,895,750 Gardner et al. July 21, 1959 2,965,249 Johansson Dec. 20, 1960 FOREIGN PATENTS 343,682 Great Britain Feb. 26, 1931 OTHER REFERENCES Blast Furnace Practice, vol. II, by Fred Clements,

1929, published by Ernest Benn Limited, London, pages 166-170. (Copy in Scientific Library.)