Distillation: apparatus – Apparatus – Elements
Reexamination Certificate
1999-12-03
2003-11-25
Caldarola, Glenn (Department: 1764)
Distillation: apparatus
Apparatus
Elements
C568S700000, C422S211000, C422S198000, C422S311000, C422S171000, C408S705000, C432S002000, C208S131000, C134S039000, C134S16700R
Reexamination Certificate
active
06652714
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to decoking or drilling coke from a coking drum. In particular, this invention relates to stabilizing the stem of a decoking drill.
2. Background Art
Coking apparatuses and decoking techniques are well known in the refining industry. Therefore, these apparatuses and techniques will be described only as necessary to appreciate the environment of my invention. Coal or hydrocarbon material is typically refined in large coke drums. These coke drums are often several stories high. Coke, a residue produced during the refining process, builds up within these drums and must be periodically removed.
Coke is removed from a drum in a process commonly known as decoking, cutting, or drilling. In a cutting process, a coke cutter or “drill” uses jets of pressurized water to break up coke residue caked on the inside of the coke drum. One example of a basic drilling apparatus and coke drum is shown in U.S. Pat. No. 2,245,554 (the '544 patent), incorporated herein by reference.
The basic decoking or drilling apparatus will be described briefly with reference to FIG.
1
. The actual cutting tool or drill bit (not shown in
FIG. 1
) is located at the lower terminus of a drill stem (e.g., piping)
10
. Pressurized water is supplied through the drill stem
10
to the cutting tool. The drill stem
10
depends from a turntable (or like rotatable mechanism and motor)
12
, which is supported by a crosshead
11
. The cutting tool, drill stem
10
, turntable
12
and crosshead
11
are all part of a drill assembly. The drill assembly is supported by a scaffolding or superstructure
17
. A pair of vertical guide rails
14
a
and
14
b
, such as I-beam channels, are provided on the superstructure
17
. During the cutting process, the crosshead
11
rides vertically on the guide rails
14
a
and
14
b
(via roller bearings or the like) to adjust the height of the drill stem
10
and cutting tool in and above a coke drum
20
. A pair of mechanical stops
13
a
and
13
b
on the guide rails
14
a
and
14
b
prevents the crosshead
11
from descending vertically below a stop position. The stop position is selected to prevent the crosshead
11
from descending too low or entirely off the guide rails
14
a
and
14
b
, while permitting the cutting tool at the end of the drill stem
10
to reach the desired depth in the coke drum
20
.
To initiate the cutting process, a top head
19
of the drum
20
is unlatched, and a stem guide (not shown) is secured to the resulting top opening of the drum
20
. The stem guide, one example of which is illustrated in U.S. Pat. No. 5,092,463 (the '463 patent), incorporated herein by reference, keeps the drill stem
10
from being thrown off-center during cutting or drilling. The stem guide shown in the '463 patent has dual clamping parts, which when open permit the cutting tool to pass through and into the coke drum
20
, and when closed closely surround the drill stem
10
. After the stem guide has been positioned on the top drum opening, the stem guide is opened and the drill stem
10
and cutting tool are lowered into the coke drum
20
.
Due to the length of the drill stem
10
and the weight of the cutting tool in the drill assembly shown in
FIG. 1
, the drill stem/cutting tool combination can behave like a pendulum. As it is lowered into the coke drum
20
, the cutting tool will tend to swing back and forth at the end of the drill stem
10
in relation to the top drum opening. This problem is exacerbated in high winds.
Even in calm conditions, two operators are typically required to position the cutting tool within the drum
20
according to the above-described configuration. A first operator controls a winch, which lowers and raises the crosshead
11
, along with the cutting tool and drill stem
10
. A second operator manually guides the cutting tool and drill stem
10
through the stem guide opening into the coke drum
20
. The second operator risks exposure to hazardous steam vapors, including high concentrations of hydrochloric sulfuric acid (H
2
S), by standing over the drum opening while guiding the cutting tool and drill stem
10
into the drum
20
. The swinging cutting tool also poses a risk to the second operator, especially during windy conditions.
These problems are not adequately addressed in the art. For example, the '544 patent only envisions a dual-plate stem guide, attaching to the top of the drum head. Like the stem guides discussed above, this dual plate configuration guides a drill stem during the cutting process. Yet, the '544 patent does not contemplate guiding and stabilizing the drill stem during its descent into the coke drum, or stabilizing the drill stem as it is raised after the decoking process is complete.
Thus, there is a need in the art for a mechanism to restrict the pendulum effect of the cutting tool and drill stem
10
. There is another need for a mechanism that obviates the need for an operator to stand over the top drum opening during insertion or withdrawal of the cutting tool. There is a further need for such a mechanism that does not interfere with the attachment or removal of the stem guide.
SUMMARY OF THE INVENTION
The present invention relates to a drill stem stabilizer that guides the movement of a drill stem as the stem is raised and lowered relative to a coke drum opening.
According to one aspect of the invention, a stabilizer is provided in a decoking apparatus that is for use with a coking drum having a top opening. The decoking apparatus includes a drill stem, a crosshead from which the drill stem depends, and a pair of substantially vertical guide rails on which the crosshead rides. The stabilizer includes a bearing encasing the drill stem so as to limit lateral movement of the drill stem. The stabilizer also includes a support member extending laterally from the bearing and attached to each of the pair of the guide rails. The support member maintains the bearing in a position to align the drill stem with the top opening of the drum.
According to another aspect of the invention, a coke drilling apparatus is provided for use with a coking drum having a top opening. The coke drilling apparatus includes a drill stem, a crosshead from which the drill stem depends, a pair of substantially vertical guide rails on which the crosshead rides, and a drill stem stabilizer. The drill stem stabilizer attaches to each of the pair of guide rails and defines an opening through which the drill stem extends. The opening is positioned to align the drill stem with the top opening of the drum.
According to yet another aspect of the invention, a stabilizer is used in a decoking apparatus that is for use with a coke drum. The decoking apparatus includes a drill stem and a structure on which the drill stem is supported for vertical movement above and within the coke drum. The stabilizer includes a bearing and a support member. The bearing encases the drill stem so as to limit lateral movement of the drill stem. The support member extends laterally from the bearing and attaches to the structure. The support member maintains the bearing in a position so as to guide the drill stem into and out of the coke drum.
Another aspect of the invention relates to a stabilizer in a decoking apparatus that is for use with a coking drum having a top opening. The decoking apparatus includes a drill stem, a crosshead from which the drill stem depends, and a pair of substantially vertical I-beam guide rails defining channels in which the crosshead rides. The stabilizer includes a bearing made up of a complementary pair of half-cylindrical rings. Each half-cylindrical ring includes a pair of mating longitudinal faces and a flange extending from near each of the pair of longitudinal faces. The two rings are attached to one another via the flanges so as to form a cylindrical ring. The cylindrical ring encases the drill stem so as to limit lateral movement of the drill stem. The stabilizer also includes a support member having two I-beam segments e
Caldarola Glenn
Fitzpatrick ,Cella, Harper & Scinto
Foster Wheeler Corporation
Wachtel Alexis
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