TABLE OF CONTENTS

The GEA solution consists of a three-stage cascade system:
• The first stage includes thee GEA Grasso V 1100 speed-controlled refrigeration
units. These cool the glycol-water circulation system to T0 = -5°C, with a temperature
of Tc = 16 to 35 °C achieved on the compressor side;
• The second stage features one GEA Grasso 810 compressor, which has a T0 of 16 to
35 °C, and raises the temperature to 43°C;
• The third stage features two GEA Grasso 65hp heat pumps that raise the temperature
from 43°C to 80°C.
The heat pumps use not only the exhaust heat from the refrigeration units but also
virtually all waste heat produced in the entire plant.
Results
Following the feasibility study for the ammonia system proposed by GEA, which
showed net saving in utilities and a return on capital expenditure of 1.5 years, Robert
Wiseman Dairies decided to invest in the combined central ammonia refrigeration
plant and heat pump.
The investment meant there was no need for a boiler, which displaced a significant
amount of gas, which as projected improved the payback. The capacity of the ammonia
units, which is about 1MW, suffices not only for the pasteurisation but can also serve for
the clean-in-place units.
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The end result for RWD has been:
• A saving in CO 2
per year 1,135,000kg
• A net reduction in electrical energy for refrigeration and heating of 20%
• A reduction in gas usage of 52% from 6,470 CU. FT to 3,200 CU. Ft (52%)
• A water reduction of 50%