Chemical Engineering March 2023 - 37

Marmon Industrial Water
FIGURE 2. A precoat demineralizer system can help to remove contaminants
from condensate streams, making water reuse more economical
raise 1 lb of water
by 1ºF, and while
the temperature of
condensate typically
hovers around
200ºF, makeup
water usually enters
the system at
55ºF. The cost of
fuel required to raise
the temperature of
water by 145ºF is
significant. Furthermore,
there are significant
wastewatertreatment
costs
associated with
dumping
the
dirty
condensate, as detailed
in Table 1.
Marmon Industrial Water
FIGURE 3. A precoat demineralizer system combines filtration elements
and ion-exchange resins within a specially designed process vessel
The high cost of blowdowns
The traditional method of removing
contaminants is a blowdown, which
involves essentially purging all the
water from the condensate loop at
once and replacing it with fresh water.
For large plants, this can amount to
tens of thousands of gallons of water
per blowdown. This loss of water has
numerous associated costs, not just
due to the cost of fresh replacement
water, which is rising steeply across
all regions, but also the costly steps
required to make it ready to convert
into steam. These steps can include
pre-treatments, such as clarifying,
filtration, softening, dealkalyzing, reverse
osmosis and deionization, and
chemical treatment, such as neutralizing
amines. In addition, the largest
cost comes from the energy to heat
the water. It takes 1 Btu of heat to
Fresh water Makeup water
treatment
$0.30-0.50
$0.34-0.50
Recover condensate
One technology that
offers a viable solution
for minimizing
blowdowns is a precoat
filter demineralizer
(Figure 2). This
is a condensate polisher
that removes
contaminants from
condensate while
preserving the heat, allowing it to return
to the process clean and warm.
Precoat filter demineralizers combine
two distinct technologies: ionexchange
and filtration in one vessel
or application. They remove contaminants
that are present in the
steam condensate cycle by removing
suspended solids using filtration
and reducing ionized impurities to
the parts-per-billion (ppb) range, and
in some cases, to parts-per-trillion
(ppt) levels. Precoat filter demineralizer
systems are essentially vessels
with similar filter septa to those used
in pre-filters or condensate filters,
but are specially designed to act as
a support for a precoat material. Figure
3 illustrates the different parts of
a precoat demineralizer vessel. Premixed
resins available in various cation
and anion ratios, with or without
TABLE 1. ESTIMATED COST OF BLOWDOWNS PER 1,000 GAL
Chemical treatment
(neutralizing
amines)
$0.15
Energy
to heat
$5-10
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
Wastewater
treatment of
purged water
$2-4
Total cost,
per 1,000 gal
$7.80-15.15
MARCH 2023
Buss-SMS-Canzler GmbH
Kaiserstr. 13 - 15 | 35510 Butzbach | Germany
Tel. +49 6033 85 0 | info@sms-vt.com
sms-vt.com
For details visit adlinks.chemengonline.com/84645-13
37
Thin film evaporators
Short path evaporators
Static evaporators for
special requirements
Entire evaporation plants
SMS evaporation pitch:
Specialists in
Evaporation
Technology
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Chemical Engineering March 2023

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