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Case Study - Dairy Installation
Installation of Desuperheater for Dairy for
‘FREE’ hot water generation
Refrigeration and boiler constitute more than 75 % of operating energy cost
of dairy. As much as dependability of these systems is important, operating
plant efficiency and consistency in performance is also required to limit
processing cost of milk. Built-in improvement in operating efficiency
constitutes major saving opportunities in dairy utility system. Installation of
desuperheater for recovery of waste heat is major step in this direction.
REFRECON has more than 18 successful desuperheater installations in
operation since past three years. The technology is successfully implemented
for various systems using ammonia and R 22 refrigerants.
Dairy cooling requirement
Pasteurisation
Cold storage
Milk chilling
Hot water requirement
Boiler feed water
Crate / Can washing
Tanker washing
CIP
Conventional mode of hot water generation
Use of direct fuel fired hot water heaters
Direct steam injection
Condensate recovery after steam use in plant
Desuperheater mode of “ FREE “ hot water generation
With cold storage and IBT in operation, chilling plants and
refrigeration compressors operate almost 24 hours per day in dairy.
IBT takes care for fluctuating cooling demand by generating
appropriate ice thickness in IBT to maintain cold storage temperature
protecting product quality.
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Adiabatic compression in ammonia compressor results in high
discharge gas temperatures at compressor outlet. (1200 C and above)
This gas is cooled and condensed in condenser and stored in receiver
at 12 to 16 - kg/cm2 pressure and atmospheric temperature.
Condensing temperature (varying between 300to450 C) vary depending
upon type of condenser cooling and atmospheric conditions.
Desuperheater installed in ammonia circuit between compressor
discharge and condenser, removes high temperature gas heat and
passes entire gas to condenser to condense similar to normal
refrigeration cycle. Gas heat removed in desuperheater heats
circulating water up to 550 – 700 C. This recovered heat in the form of
hot water is available free of cost for various requirement in dairy.
Refrigeration plant operates almost 24 hours per day generating hot
water at specific rate. This hot water is stored in adequately sized
hot water tank to meet demand of hot water in plant as and when
required.
Schematic process diagram of desuperheater installation is enclosed
for ready reference.
ADS series of REFRECON desuperheater is specifically designed for
ammonia compressors. MOC and process parameters are appropriately
matched for life long consistency in performance. The fully welded
construction of desuperheater has complete safeties required for
installation and infinite life of operation. The desuperheater is
capable to withstand 40 bar pressure and is tested for bubble-tight
leak-proof performance at 25 bar pressure in the manufacturing
process. The perfected design results in flaw less commissioning
during field installation. The performance consistency has been proven
with number of installations and the recent one of 75 TR capacity is
jointly monitored with NDDB staff for six months. The results are
tabulated in one of the case studies listed bellow.
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Case study I
Installation cooling load
Installed capacity
Operating load
Desuperheater installation
120 TR nominal
90 TR
Suitable for 90 TR nominal (3 X 30 TR)
First installation August 2003
Balance two units March 2004
Type of savings established
Free Hot water generation
Fuel saving confirmed
Compressor operation
Avoided investment
Water Saving
18 kL per day @ 700 C
40 – 50 lit. of FO per day (steam boiler fuel)
30 – 35 lit Diesel / day (hot water boiler fuel)
Reduced operating hours 2 hrs. per day
90 TR compressors / condensers working
with 60 TR evaporating condenser.
Avoided additional 30 TR condenser
installation.
Saved 1250 liters /day evaporation loss of
water in cooling tower
Savings achieved
Fuel oil savings
Rs. 5,00,000 /- per year
Electricity saving
Rs
75,000 /- per year
30 TR condenser installation = Rs. 1.2 lac
Avoided investment
Investment for desuperheater and hot
Rs. 7,50,000 /water system, including tank and piping
Simple Pay back
13 months
Benefits (additional) that are obvious but not quantified above
1. Reduced boiler operating hours
2. Reduced or avoided maintenance of hot water generator & boiler
3. Avoided maintenance contract for hot water generator including
spares cost.
4. Reduced heat loss and CO2 emission to atmosphere
5. Benefits drawn as eco-friendly organisation image
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Case study II:
Installed capacity
Compressor Operating hrs.
Desuperheater installation
Free Hot water generation
Fuel saving confirmed (in
75 TR
16 hours per day average
Suitable for 75 TR
Compressor operation
Fuel oil savings
Electricity saving
Reduced operating hours 2 hrs. per day
Rs. 2,60,000 /- per year
Simple Pay back
Less than 6 months due to improved
condenser performance that was poor on
account of poor water quality and excess
scaling on condenser.
form of steam boiler fuel)
15 kL /day @ 530 C – 16 hrs /day working
Six months monitoring confirms consistent
savings equivalent of 58 kg of FO per day
Condenser inlet temperature dropped from
1300 C to 1150 C. Ammonia condensing
temperature reduced from 400 C to 350 C.
Estimated electrical savings are more than
Rs. 9 lac. Per annum
Investment for desuperheater system
Rs. 4,50,000 /-
Conclusion:
Looking at benefits as above installation of desuperheater in dairy as
retrofitting as well as new is commercially viable proposal. Simple Pay back
of less than 15 months and consistency in performance is assured.
Desuperheater system also offers sizable improvement in refrigeration
cycle and reduced maintenance of condenser as well as compressor. This also
enhances life of compressors as well as hot water generating equipments.
V. V. Kanetkar
Director
Refrecon Magic Systems Pvt. Ltd.
37/3 Vadgaon Khurd, Sinhgad Road, Pune. 411 041
Ph 91 20 2439 3418 / 2439 2545
Email: kvrajlal@vsnl.com
4 March 2005