Brushing – scrubbing – and general cleaning – Machines – With means to pass a solid cleaning agent and a fluid...
Patent
1990-11-16
1992-12-15
Roberts, Edward L.
Brushing, scrubbing, and general cleaning
Machines
With means to pass a solid cleaning agent and a fluid...
15104062, 165 95, B08B 904
Patent
active
051705249
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to apparatus for the cleaning of tubes, in particular tubes arranged in regular arrays such as those forming part of multi-tube heat transfer devices such as boilers, tube and shell type heat exchangers and condensers. More particularly, the present invention relates to parts of tube cleaning apparatus including launchers of cleaning projectiles and refinements to the barrels and muzzles of launchers to improve their engagement with the ends of tubes to be cleaned.
BACKGROUND OF THE INVENTION
Tubes in multi-tube heat transfer devices usually require cleaning on a regular basis. For the most part, this is accomplished by lancing, a manual or partly-mechanized process in which the nozzle of a flexible or rigid lance, emitting high velocity jets of water, is passed through each tube. When manually performed, lancing is an arduous, dirty and dangerous task. Large volumes of effluent are generated, which often contains toxic substances. The cleaning jets of high velocity water are capable of inflicting severe injury. Environmental regulations governing the disposal of effluent are strict and the production of minimal effluent volume is thus desirable. A rigid lance must be as long as a tube to be cleaned if cleaning is to be effected in a single pass. Particularly in long tubes, manipulation of lances generally and the head space required for deployment of rigid lances often represent a considerable problem.
Australian Patent Applications Nos. 18,165/83 and 32,187/84 disclose a method of cleaning multi-tube heat transfer devices such as boilers, condensers and heat exchangers. In the method disclosed therein, a tube is cleaned by propelling into and through it a projectile made to travel at high speed by means of a more or less instantaneous release of a pressurized liquid cleaning medium. In most applications, it is usual for the said cleaning medium to be water with typical working pressures ranging from 1,000 to 10,000 P.S.I.
The aforementioned patent specifications use the term "pig" to describe the said projectile, however, this terminology is considered not to be altogether appropriate as the cleaning method differs from the well-known pigging cleaning method in material ways. In pigging, the pig is constructed so that its outer or forward surfaces, or auxiliary scraping, abrading or brushing elements attached thereto, are kept firmly in mechanical contact with the inner surfaces of a pipe or tube being cleaned. The pig is drawn or propelled slowly through the tube or pipe, the said surfaces or auxiliary elements effecting the cleaning in a direct, mechanical way. In the present method, the projectile is made to have a light sliding fit in the bore of a tube to be cleaned or of a diameter to approximate the reduced lumen created within the tube by a heavy accretion of contaminant material. Thus it cannot itself mechanically remove contaminant material.
In operation, where a tube is completely blocked, the release of the pressurised cleaning medium causes the projectile to accelerate rapidly into the tube, whereupon the projectile and its propelling column of liquid cleaning medium are arrested violently by the projectile's coming into contact with the deposit of contaminant material. It is believed that the resultant water hammer effect causes an energetic shock to pass along the length of the tube, breaking the bond between its inner wall and the contaminant material. In some types of monolithic crystalline deposit, the said shock causes the contaminant material to revert to a granular or particulate form. The loosened contaminant material is ejected from the tube by the projectile, its progress through the tube being assisted by pressure pulses in the following column of cleaning medium. The said pressure pulses are generated by the action of the pistons of the multi-cylinder positive displacement type pump preferably employed to pressurized the said cleaning medium.
Where the progress of the projectile through the reduced lumen of a tube is imped
REFERENCES:
patent: 1808870 (1931-06-01), Strasburg
patent: 2915422 (1959-12-01), Stone
patent: 3631555 (1972-01-01), Hurst et al.
patent: 4435872 (1984-03-01), Leikam
patent: 4724007 (1988-02-01), Barry et al.
Barry Bros. Specialised Services Pty. Ltd.
Link Ernest V.
Roberts Edward L.
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