Tímarit Verkfræðingafélags Íslands - 01.12.1967, Blaðsíða 101

TÍMARIT VFl 1967
99
Aðal ókostirnir eru hár vélakostnaður og hár
framleiðslukostnaður. Frostþurrkuð matvæli eru
notuð mestmegnis sem íblöndmi í tilbúin mat-
væli og þar, sem hin sérstöku gæði frostþurrkuðu
matvælanna eru veigameiri en hærri kostnaður
þeirra.
Geislahitun er meir og meir notuð þar, sem
hún veitir möguleika á meiri sjálfvirkni. Gufu-
þéttirinn (Vapour Trap) og loftdælurnar hafa
verið þau atriði, sem mest hafa verið þróuð í
vélabyggingunni síðustu árin. Frostþurrkun sem
iðnaður hefur þróazt mjög ört og ryður sér til
rúms.
Umrœður
Sveinn S. Einarsson:
First I like to thank Mr. Begtrup-Hansen for
his informative lecture. I have looked through
Ettrup Petersen’s paper and found there a
break-down of the total processing cost in the
freeze-drying industry into the following com-
ponents, (1) fixed costs such as: capital cost,
insurance and management, — (2): labour
costs, and (3) utilities.
I presume that utilities would mean such
items of costs as outlays for heat-energy, electri-
city, cooling water, possibly nitrogen and other
such items. It cannot be seen, however, whether
such items as packaging costs are included, or
whether they are left out entirely.
I find the cost, quoted for the utilities, rather
low in comparison with similar figures, which
I have seen before — ranging from 2,2 U.S. cents
per kg of water evaporated for a 32 tons per
day plant — up to 3,5 cents per kilo for a 4 tons
per day plant. Accordingly, I would like to ask
Mr. Begtrup-Hansen, whether he could give us
a break-down of the figures for the utility cost,
specifying the actual use of the various utilities
in kwhours, kgs of steam, litres of cooling water
etc. per kilo of water evaporated, as well as
some idea about the unit prices used in each
case as a basis for his calculations.
It is worth noting that even if the utility
figures quoted are perhaps a little low in my
opinion, they still represent a substantial portion
of the total processing costs in freeze-drying.
Using Dr. Petersen’s figures, the costs of utilities
represent from 23% to about 30% of the total
precessing costs, even if the freeze-drying equip-
men is very expensive and the capital costs
accordingly rather severe. This is in line with
what is commonly known that the freeze-drying
process has a very high energy demand, and
that it is difficult to use it for processing other
than relatively high priced products in countries,
where you have to pay the ordinary prices for
power or fuel.
In this connection, I like to call attention to
very special circumstances here in Iceland,
which can possibly mean that freeze-drying
could be used with advantage also for relatively
low-cost products like fish. In the many high-
temperature geothermal areas of Iceland, we
can produce heat energy in form of steam, or
generate electric energy at an exceptionally low
price. Cooling-water of only 4-5°C, which is the
ordinary groundwater temperature here, is also
abundant in most areas. The geothermal steam
or hot water of temperatures up to, say 170-
180°C, is very well suited for the heating, for
the vacuum production, and even for the freez-
ing, involved in the freeze-drying process.
As to the costs, I can quote the following
figures:
(1) Geothermal steam can be produced on the
steam-field at a price of 25-60 U.S. cents per
ton, depending on the extent of the steam
production — the lower figure refers to pro-
duction of the order of 300 tons of steam per
hour, whereas the higher is applicable for
production rates of the order of 20-30 tons per
hour.
(2) : Electrical power can be produced at a
price of approximately 2,5-3,0 U.S. mills per
kw hour (1 U.S. mill = 0,001 U.S. $).
To this must of course be added the trans-
mission costs that, in the case of the steam,
can be considerable, even if super-heated water
would be used as the heat carrying medium, as
would be done in the case of transmission over
any longer distances. Even so, the cost of the
heatenergy would be exceptionally cheap, per-
haps of the order of 2 or 3 U.S. dollars pr. 1
Gcal. (1 Gcal = 10° cal.). It is not in many