Slovenian brewery ammonia refrigeration conversion yields significant savings

This second article about brewery modernisation and the benefits of new ammonia refrigeration installations takes us to Slovenia, where the Lasko brewery achieved space, energy and water savings after replacing 9 pipe bundle condensers with 2 ammonia evaporative condensers, also putting in fully hermetic ammonia pumps, screw compressors and frame heat exchangers. The conversion was achieved without interrupting beer production.

The Pivovarna Lasko beer, easily identified by the logo depicting a chamoix buck, is brewed in the town of Lasko in the heart of Slovenia. The brewery’s previous refrigeration plant, installed in the 1970s, became inadequate for the growing brewery and its increasing production. Huppmann, refrigeration specialists with knowledge of both the brewing industry and industrial refrigeration, were selected to undertake the re-design and set-up.

New ammonia system must meet strict criteria

With the refrigeration plant - the brewery’s main energy-consumer - accounting for more than one third of the electricity used, it was decided that the new installation would have to:

Save energy
Reduce water consumption
Exceed all the requirements of the relevant European standards

Three temperature levels instead of two

The previous refrigeration plant operated at -5°C for the brewing water pre-cooling and at -10°C for cooling all other refrigeration appliances. The -5°C circuit was inefficient because it cooled to an unnecessarily low temperature. As a result, the new system has three temperature levels:

+- 0°C for brewing water pre-cooling;
5°C for fermentation refrigeration with direct evaporation;
-10°C for room cooling, beer refrigeration and pasteurising.

Implementation of the three temperature levels resulted in energy savings of 13%.

Components of the new ammonia installation

2 ammonia evaporation condensers: Replaced the 9 pipe bundle condensers and 8 water cooling towers, reducing energy and water consumption, and requiring noticeably smaller space requirement;
New supply lines;
Automatic ventilation system;
Closed refrigeration circuit with glycol: Replaced the open cooling water circuit that used to carry dirt into the system, and will result in less need for servicing;
Fully hermetic ammonia pumps: Responsible for cooling the tanks and replaced the previous open pumps;
Frame heat exchangers: Replaced 5 pipe bundle evaporators;
Block section valves and an ammonia alarm: Safeguard the ammonia separators and allow all ammonia forward and return lines to be individually regulated while closed;
Automatic desalination system and dosing unit for chemicals: Installed to protect the plant against corrosion and prevent algae growth;
S7 controller and universal brewmaxx control system: Enable condensers to be controlled according to the prevailing ambient conditions such as temperature, humidity, whether it is day or night;
One large refrigerant collector: Replaces 4 small collectors;
Screw compressor: Replaces piston compressor for brewing water pre-cooling.

Winter conversion avoids production disruption

The conversion was mainly undertaken in the winter months, when parts of the old plant could be shut down without affecting production thanks to the lower ambient temperatures. A special ammonia suction plant was used to avoid any risk of ammonia pollution during the conversion.

The new plant was designed so that based on refrigeration needs the control technology selects only those refrigeration machines necessary to meet the cooling requirements, switching off those that are not needed.

GEA Brewery Systems

The Slovenian installation uses GEA Brewery Systems ammonia refrigeration technology. GEA was one of the first manufacturers to use ammonia for direct cooling of fermenting tanks, which has the advantage of a controllable higher heat transfer rate. In comparison to indirect cooling with glycol the energy savings are usually over 14%.