Process Refrigeration for a Confectionery

Planning / Implementation / Main components

Dresen + Bremen GmbH

Refrigerant

Ammonia (NH₃)

System start-up

2004

A leading German confectionery manufacturer erected a new production building in Halle/Westphalia, Germany. Here Dresen + Bremen installed a refrigerating plant for process refrigeration and air-conditioning, using the natural refrigerant ammonia.

Demands

The confectionery manufacturer practices sustainable development and wanted to reorganise its production process along profitable, environment-friendly lines. The aim was therefore to find an environment-friendly process refrigerating system with low energy consumption and reliable operation.

Solution

Process refrigeration is responsible for controlled heat removal during the production of chocolate, sweets and fruit gums, and for cooling the machines. The focal element of the central plant consists of four frequency-controlled screw compressors. The consumers are supplied with refrigeration via two liquid circuits at temperatures between 5°C and 11°C. The process refrigeration circuit uses cold water, while the air-conditioning system works with a propylene glycol circuit. Plate heat exchangers are responsible for energy transfer using the effects of gravity. The evaporation temperatures are 3°C in each case, with condensation temperatures of 33°C. On completion of the two-phase expansion project, refrigerating capacity in the production section will be approx. 1.5 megawatts and approx. 2.8 megawatts for air-conditioning.

Type of facility (circuit)

Central plant

Refrigerant

NH₃

Refrigerating volume

1,800 kg

Secondary refrigerant

Production: cold water
Air-conditioning: propylene glycol

Refrigerating capacity

1.5 MW + 2.8 MW

Main components

4 frequency-controlled screw compressors, plate heat exchangers, 5 evaporative condensers

Special features / Comments

The waste heat from the screw compressors is used to heat process water in a closed glycol circuit. The refrigerating system is accommodated in a central steel structure roof facility over the production unit.