The model OS.A95 screw compressors by Bitzer: the typical applications include medium and low temperature refrigerated distribution warehouses, shock freezers and process liquid chillers.
(video: Bitzer)

Bitzer ammonia compressor pack to maintain correct temperature in cold stores

Christoph Beidecker (left), Technical Director at Bochumer Fleischhandel, and Moritz Kruse, responsible for planning and project management at 3K Kälte- und Klimatechnik Kruse GmbH (3K), are delighted with the successful project. (photo: Bitzer)

An absolute must: fail-safe cooling. Up until 2017, an outdated NH3 system had been doing the job. The slaughterhouse has been using a Bitzer ammonia compressor pack (ACP) since September 2017, installed by company 3K Kälte- und Klimatechnik Kruse GmbH based in Versmold. Moritz Kruse takes motorway exit no. 34 on the A 40, Bochum-Freudenbergstrasse, and then it’s just a short drive of a few minutes to EG Schlachthof Bochum. Approximately 350 cattle and some 1,500 pigs arrive here every day from all over the region to be processed into meat.

A few months ago, Moritz Kruse and his colleague from company 3K Kälte- und Klimatechnik Kruse GmbH installed a Bitzer ammonia compressor pack (ACP) at the slaughterhouse.

Up until September 2017, an outdated NH3 refrigeration system had been maintaining the correct temperature in the cold stores. The project team was also tasked with tempering the production cooling, which at that time was still operated with refrigerant containing CFC, in the future using the new set-up and a brine system.

High-quality screw compressors: the cooling capacity of 400 kW at that time for the slaughterhouse

So it was a good job Andreas Schulaks, Head of Industrial Refrigeration at Bitzer, had already approached the 3K company in 2015 to introduce the Bitzer ammonia compressor packs.

“This was the optimal time for a field test for us,” he says. “We were certain that our ACP with three Bitzer OSKA 85 screw compressors was just the right solution for the slaughterhouse operations based on the set-up.”

The slaughterhouse required an actual cooling capacity of approximately 400 kW at that time. As a result of the planned conversion to non-CFC refrigerant, a decision was also made to equip the processing rooms with a brine system which is cooled by means of the ammonia circuit of the refrigeration system.

Access to cooling capacity of 1,548 kW at full machine capacity, with a COP of 4.28

“We therefore needed a cooling capacity of around 1,150 kW. The three screw compressors each have a capacity of 400 kW at 2,900 rpm. Thanks to the option to have the compressors turn at 4,200 rpm, we can also ensure that, in the case of a machine malfunction, we have sufficient redundancy, without having to deal with a significant loss in capacity and thus production downtime,” says Moritz Kruse.

“So we have access to cooling capacity of 1,548 kW at full machine capacity. The economiser capacity is then 125.8 kW.” Thanks to the economiser with sliding suction position, operation is also effective in part-load. “We therefore obtain the highest cooling capacity and coefficient of performance possible in full- and part-load. In April 2018, the total power consumption of the system was 67,988.0 kWh for the three Bitzer screw compressors, putting the system’s COP/EER at 4.28 at the machine shaft – a figure that can actually be measured,” Moritz Kruse adds.

The additional emergency cooler on the roof for system reliability
The system’s oil cooling also offers heat recovery to preheat the feed water for the heating system: the water is heated to 56°C, with 124.6 kW oil cooler capacity available at full-load. The 3K company has installed an additional emergency cooler on the roof for system reliability. “Our Bitzer screw compressors are responsible for cooling the pig and cattle cold stores and ensure continuous operation of the ammonia refrigeration system,” says Andreas Schulaks. “In the future, they will also provide tempering in the production facility in a secondary circuit. According to plans, the capacity for this circuit will be around 750 kW.“

Challenge: minimal production downtime during system replacement

3K began planning the project in October 2016 and, three months later, the technicians received the order from Schlachthof Bochum.

In turn, Bitzer delivered the unit in April 2017, which was then installed with the corresponding pipelines and additional devices.

“At the same time, the company Automatisierungs- und Steuerungstechnik Austmann (ASA) replaced the system controls and the switch board for machine regulation,” says Moritz Kruse.

“We’ve been successfully working with our partner for many years.” And then in September 2017, the 3K technicians switched over from the old to the new system.

“One of the biggest challenges for us during system construction was minimising cooling downtime to the highest degree possible,” says Moritz Kruse. “But because the engine room is so spacious, we were able to set up the new system alongside the existing one.”

And with the support of Bitzer experts from Denmark, Moritz Kruse and his colleagues actually managed to keep downtime to a bare minimum: the new system went online after 54 hours rather than the initially estimated 72. As a result, production at the slaughterhouse was back up and running much earlier and production downtime was limited.

Bitzer as a reliable partner in commercial refrigeration

The decision to go with the Bitzer ACP was obvious for project manager Moritz Kruse.

“We’ve been working with Bitzer since 2016. Andreas Schulaks introduced us to one of the ACP prototypes during a factory tour in summer 2015,” says Moritz Kruse. “Bitzer compressors are durable, ultra-reliable machines that are well established in commercial refrigeration. And now that Bitzer also offers entire units, we’re more than happy to also use the high-quality screw compressors, which until recently were rarely ever utilised in industrial refrigeration. After all, the fact that we no longer have to construct the units ourselves is an absolute competitive advantage for us,” Moritz Kruse adds.

And thanks to the integrated IQ module, the cabling required very little effort on the part of 3K – for both installation and commissioning. There’s also the fact that Bitzer compressors can be operated continuously. Even if the capacity control were to malfunction, hand operation would also be a good option that doesn’t require much effort with the high-quality screw compressors.

“All that together, the simple servicing of the units and compressors, made the decision to go with Bitzer an easy one,” says Moritz Kruse. And Andreas Schulaks adds: “Because our ACPs boast such a compact, well-structured design, they can also be used for renovations in smaller engine rooms and represent a simple, cost-effective solution for new structures, as engine rooms can be that much smaller.”

Bitzer manufactured the open drive high-quality screw compressors in Rottenburg-Ergenzingen in southern Germany, whilst the ammonia compressor pack was premounted at the neighbouring Rottenburg-Hailfingen site.

Moritz Kruse is now standing in front of the system in the Schlachthof Bochum engine room. “The entire project has run smoothly and continues to do so to this day, from the planning and implementation to collaboration following commissioning,” says Moritz Kruse. “All that is a great recommendation for Bitzer, who will continue to be a reliable partner well into the future.”

High-quality screw compressors for refrigeration, air conditioning, process cooling as well as transport

As an independent specialist for refrigeration and air conditioning technology, Bitzer is present all over the world: with products and services for refrigeration, air conditioning and process cooling as well as transport, Bitzer ensures optimum temperature conditions for trade in goods, industry processes and indoor climate control – always considering highest possible energy efficiency and quality. Bitzer is represented all over the world with 72 sites in 37 countries, including its sales companies and production facilities. Trade and service partners included, the Bitzer network of manufacturing, development and sales extends to almost all countries in the world. In 2019, 3,800 employees generated a turnover of €808 million; expenditure for research and development totalled €46 million.