Technical specifications and facts about the PWR BLOK (generation 3) unit.

Technical Specifications

The PWR BLOK generation 3 unit is the industrialised version of the PWR BLOK unit, of which Swedish Stirling is presently starting mass production. The primary developmental focus of generation 3 has been on modifications and upgrades of the PWR BLOK unit that reduce production costs, facilitate operation and maintenance, enable the smallest possible environmental impact, and facilitate energy recovery. Standardisation, Modulisation, Size reduction, Version limitations, Standardised stock item range, Design-to-Cost and Design-for-Assembly have been some of the watchwords for the development work.

Various technical facts about generation 3 of the PWR BLOK unit are given below. The exploded view drawing below also shows the different components and subsystems that can be found in the unit’s “warm” and “cold” compartments.



Standardisation for low production and operating costs

PWR BLOK generation 3 has identical dimensions, with a 40ft-High Cubicle (compared to the previously somewhat unusual 45ft) Container, and can be handled as such along the entire transport chain to the final destination. This means low transport costs. The unit is divided into a warm compartment (the side with the Stirling units), and a cold compartment – the Service side – into which mainly temperature-sensitive components are fitted. The unit consists of 7 completely identical cells with space for two Sterling units, a lower and an upper one, in each cell. The 14 Stirling units are also completely identical, and contain a Stirling engine and a generator, as well as other components. This means we have a minimal number of items in production and as spare parts. Having spare parts for one Stirling unit is tantamount to having them for all 14 units. Modifications in generation 3 also increase the usage rate for the customer. If the control computer shuts down an engine due to a fault of some kind, and it does not restart after a number of attempts, the faulty Sterling unit can be replaced with one that works in less than 15 minutes.


Lowest possible environmental impact

PWR BLOK gen3 also has less environmental impact than the previous version. We have chosen to use Magnelis plating, with its unique surface treatment that does not require aftercare, for the sides and top. This means that only the container’s welded structure needs to be painted, and therefore we save on litres of paint, resulting in a lower environmental impact and lower cost. For the same reason, and on account of specific requirements, we also use a lot of stainless steel, mostly for pipelines. We have also minimised material consumption by reinforcing the containers with a number of temporary, diagonal, tension rods during transport, and thereby also minimised costs. The components to be assembled on the exterior of the PWR BLOK unit during installation are enclosed internally in the PWR BLOK unit until they reach their destination, where they are unpacked and assembled externally. PWR BLOK gen3 also has a very high end-of-life energy recovery rate after approximately 25 years of service.



Robust safety systems

As the residual gases from metal production that are used as fuel are both toxic and potentially explosive, strict safety regulations apply to our product. The PWR BLOK has a number of automated, built-in safety features. There is a pre start-up check for instance, to ensure that we have access to nitrogen gas, fuel gas and working gas, all at the correct pressure, before it is even possible to start up the Stirling units. All of the safety features are built-in, and each Stirling unit and all of the other subsystems in the PWR BLOK unit are continuously and individually monitored by the process computer in the PWR BLOK unit. We also have subsystem pressure sensors, pressure switches, level sensors etc., which monitor processes and safety. If, in spite of all of these safeguards, some form of leakage should occur, we have gas detectors at strategic positions that sound the alarm and suspend the process. If a Stirling engine’s combustion chamber is not working as intended, the control computer shuts down the Stirling engine in question, and then proceeds to automatically flush the combustion chamber and exhaust gas piping with nitrogen gas, which ensures that no combustible gas or oxygen remains in these parts of the PWR BLOK unit.


Other systems during installation

The PWR BLOK unit is the largest and most complex unit that is installed on-site, but there are two additional units to the PWR BLOK that are installed. The first is a fuel gas unit, which ensures that the fuel gas is at the correct pressure and has a low moisture content, as well as filtering out larger particles from the gas before it is fed into the PWR BLOK unit. The other unit is a large, standardised industrial cooler (9m long), which provides the Stirling engines in the PWR BLOK unit with cooling water.