WATER JET CONFERENCE - Waterjet Technology Association

Throughout the development of the systems, problems existed which were not
immediately solvable since no equipment was available on the market. The problems
were:
1. The hoses becoming caught in the cleaner frame.
2. The swivel couplings burst because of the high radial and axial loads they
encountered and also dirt and acid ingress to the vital parts such as seals and bearing
areas, etc.
A decision was made to design a swivel coupling which would overcome all these
problems and would, through necessity, incorporate the following features:
1. Low breakaway torque, low dynamic friction.
2. Rugged design with robust bearings.
3. Would withstand the high operating pressure and intermittent high temperatures.
4. Very fast seal replacement in the vent of seal failures.
5. Would be resistant to acid attack and dirt ingress.
Prototypes of the swivel design were made and fitted to a coke oven plant on June
21st, 1982. So far these swivels have performed very satisfactorily and have had, to date,
no seal failures or failures of any kind. They have completely eliminated the problem of
the hoses kicking out sideways when the lance turns a corner, thus preventing the hoses
from getting caught in the cleaner frame. The swivel couplings (see figure 9) are made of
stainless steel and incorporate a large heavy duty roller bearing carrying the main shaft
and a large heavy duty roller thrust race which carries thrusts developed by the high
operating pressures. The swivel is fitted with a very high specification, low friction,
pre-stressed seal, which is supported by an anti-extrusion ring. Many of these swivels
have been made to date and so far not one has failed in any way. Since the swivel design
has quite a large outside diameter, it was decided to bore out the carriage and fit clamps
to accept the new design of swivel so that it was rigidly supported. Screwed directly into
the swivel are the lances for cleaning the seals.
FINANCIAL ASSESSMENT
The installation of the water jet door cleaner will reduce the number of ovens lost
due to the inability to latch doors after pushing because of their dirty condition. The
number of ovens lost before the water jet cleaner became operational was 30 per month.
This has now been reduced to 10. A saving of 20 ovens a month was made and this will
increase the coke output by 4,080 tons per annum, assuming a wet coke output of 17 tons
per oven. There are other expected savings, but these cannot be evaluated:
(A) Reduction in maintenance costs because of the reduced oven door jamb and
refractory damage due to firing around ovens caused by overheating and distortion.
(B) Slight increase in gas (by-product) production because it is recovered and not burned
around the door seals. Total savings are unaccountable here. But nonetheless, there are
some savings.
20 ovens per month X 12 = 240 ovens per year
17 X 240=4,080 tons
4,080 tons X $75=$306,000 per year
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