Cetetherm Mini adds to the efficiency of Swedish municipal energy project

Hjo Energy AB is an energy supplier owned by a municipality in the mid-western parts of Sweden. The heartland of their distribution network is the city of Hjo, situated on the western shore of Lake Vättern. As part of its environmental policy, Hjo Energi AB has developed a district heating network that has been expanded gradually since 1999 – i.e. when the first boiler plant was built. Substations from Alfa Laval have played an important role in this process. During the most recent phase, a number of Cetetherm Mini were selected to reap the full environmental effect of the priority given to district heating. Today, emissions from more than 800 m3 of oil have been eliminated by the use of biofuels. Hjo Energy thus meets the national goals for reductions of CO2 emissions with a safe margin.

Growing with the region

The district heating infrastructure devised by Hjo Energy comprises a culvert network of 24 kilometres, providing space and tap water heating for subscribers in 92 industrial buildings and residential blocks and 390 single-family houses. The heat is produced in two boiler plants fuelled by wooden chips, while an oil boiler is kept for emergency and peak performance back-up. Since some 95 percent of the annual heat production can be based on biofuel, the reduction of CO2 emissions is considerable. Kenneth Eriksson is a project manager at Hjo Energi. He describes the plans for the near future:

– We are not going to expand the network during the next few years. At present, we are targeting some major industrial operators and we also try to increase the “subscriber density” within areas comprised by the present culvert network. In the long run, the development of the general infrastructure in the region will decide how and where we will extend the present network.

During the most recent phase of expanding the district heating network, a number of apartments (14 in all) were connected. They were all situated in small residential buildings, each comprising 4 apartments. Kenneth Eriksson summarizes:

– The substation we selected – Cetetherm Mini – supplies the water for indoor heating as well as hot tap water. The use of water and energy can be measured for each household separately and the total energy consumption can be reduced. Residents are very satisfied with this solution, since it offers them a combination of increased comfort and cost reduction.

A natural choice

The selection of Cetetherm Mini as a substation for the most recent extension of the district heating network was natural.

– The purchase procedure was conducted according to the legal framework, with a detailed demand specification. We found Cetetherm Mini a natural choice, since its functional profile and cost balanced very well. The simple installation offered by this substation was one of the significant factors. The Mini has low weight, compact measures and a piping layout facilitating installation by offering multiple mounting alternatives.

Hjo Energi has some previous experience from cooperation with Alfa Laval. As a fact, our company has delivered most substations within the district heating network in Skövde. According to Kenneth Eriksson, this adds a kind of natural warrant to the project.

– What we ultimately purchase from our equipment suppliers is not products – but functions. These functions are expected to be costeffective and reliable. By experience we know, that the people from Alfa Laval share this perspective. They provide valuable training for our people and take an active interest in the continuous performance of the products.

A growing global interest

Cetetherm Mini is a complete plug-and-play substation providing both heating and hot tap water. It is designed specifically for single family houses and apartments connected to the primary side of the district heating network. The temperature control (indoor temperature and tap water) is fully automated and the control panel is preset. Once mounted, the substation can therefore be started practically immediately.

Cetetherm Mini reflects the growing interest for substations designed for efficient duty in small to mid-size apartments and single-family homes. A growing global environmental concern has triggered an interest for district heating technology applied within networks of moderate extension. With the development of district heating technology, it now offers multiple benefits besides the economies of scale. During the last few years, Alfa Laval has mobilized vast resources to develop technology for efficient “community heating” – i.e. heat distribution from a central boiler station providing heat to subscribers in a relatively small neighbourhood.

The energy policy declared by Hjo Energi AB is a representative example of the driving force behind the Alfa Laval R & D efforts. Our customers ultimately command the allocation of our development resources. Among colleagues, we use to call this “evolution by listening”…

Some basic facts on Cetetherm Mini

• Tested according to ISO 9001:2000
• Fully automated temperature control
• Tap water supply at even temperature
• Tap water from separate circuit
• Piping and plates out of acidresistant steel
• Compact measures, low weight & flexible piping
• “Plug & Play”-design. Swift and simple start-up
• A wide span of optional equipment

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