Cleaning and liquid contact with solids – Processes – Hollow work – internal surface treatment
Patent
1993-08-12
1997-02-04
Lieberman, Paul
Cleaning and liquid contact with solids
Processes
Hollow work, internal surface treatment
134 34, 210632, 435264, 510245, 510392, B08B 900, C11D 3386, F28G 1300
Patent
active
055994024
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/DK92/00072 filed Mar. 6, 1992.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention comprises a method for cleaning of heat exchangers after passage through the heat exchangers of a fluid which comprises vegetable dry matter, and which by transport through a passage will tend to generate deposits on exposed positions in the passage. Such fluid is typically a fluid, pulpy material, preferably fruit or vegetable juice, e.g. orange, pineapple, grape fruit, banana, grape or apple juice, or carrot, tomato, or celery juice. For the sake of brevity in the following such fluid will be identified as "fluid, pulpy material", and the deposits will be identified as pulp or pulp particles. The heat exchangers are preferably of the plate type.
In order to generate a good heat exchange the plates in a plate heat exchanger are usually placed in close proximity to each other, e.g. with a gap of around 2.2-6 mm, preferably 3.5-4 mm. Also, two adjacent plates have to touch each other at several hundred pointed positions per m.sup.2 in order to secure the physical stability of the plate package during operation, when the pressure differential is at its maximum. It has been found, however, that the free passages between two adjacent heat exchanger plates are being clogged or at least narrowed considerably after passage of fluid, pulpy material, due to obstinate adherence of pulp particles to the plates, especially at the above indicated pointed positions, where two adjacent plates touch each other. This layer of pulp particles has to be removed from the heat exchangers in order to reestablish a satisfactory performance of the heat exchangers and furthermore for hygienic reasons. Also, if the pulp particles are not removed effectively, they can be released during a later heat exchange with a clear liquid, e.g. clear apple juice, which would be detrimental to the quality of the clear liquid. Hitherto two methods have been used for the purpose of removing the pulp particles from the heat exchangers. In the first place the plate heat exchanger assembly can be dismantled completely and cleaned mechanically. This is effective, but also a time consuming and cumbersome method. Ordinarily the so-called cip method (cip is short for cleaning in place) is used, i.e. great amounts of high pressure water is flushed through the heat exchanger in order to remove the layer of pulp particles, and also hot lye (NaOH) and/or a peroxide solution or hot lye and complex builders, such as EDTA, is flushed through for cleaning purposes. Even if this method is effective, it is time consuming, as it ordinarily lasts around 2-4 hours, and also energy consuming due to the necessity of the supply of high pressure water, the lye and/or peroxide solution treatment damages the rubber gaskets, which have to be replaced at shorter intervals, and also the lye and/or peroxide treatment presents an environmental problem. Furthermore, especially EDTA also presents an environmental problem. Also, in case the cip method is used, it has been found that even so it is necessary at certain time intervals, e.g. once a week, to dismantle the plate heat exchange assembly completely and carry out a mechanical cleaning. This cleaning problem is not a minor problem, but a problem which haunts the industrial world to a significant degree in consideration of the fact that on a global basis the annual amount of fluid, pulpy material which is sent through heat exchangers, run into millions of tons. Great efforts to solve this problem have been exercised, but so far in vain. An attempt to circumvent the problem is the so-called free flow heat exchanger, in which the gap between adjacent plates is much larger than in ordinary plate heat exchangers and in which no contact points between adjacent plates exist; however, the heat exchange capacity in such free flow heat exchangers is unsatisfactorily low.
Thus, the purpose of the invention is the provision of a method for cleaning of heat exchangers after passage of fluid, pulpy materia
REFERENCES:
patent: 3406089 (1968-10-01), Yerkes et al.
patent: 4338399 (1982-07-01), Weil et al.
patent: 4388330 (1983-06-01), Wobben et al.
patent: 4936994 (1990-06-01), Wiatr
Greve Folmer
Stutz Christian
Douyon Lorna M.
Lieberman Paul
Novo Nordisk A S
LandOfFree
Method for cleaning plate heat exchangers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for cleaning plate heat exchangers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for cleaning plate heat exchangers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-674907