Buffer tanks for CHP projects

At Mibec we supply a wide range of water storage and Buffer tank products; in this short article we take a closer look at the application of buffer tanks in Combined Heat and Power (CHP) systems (projects where the power generation unit produces both heat and electricity for one or more buildings).

Buffer tanks form a key component in CHP systems, with their primary purpose being to smooth out the loads and demands on heating and hot water over the course of the day from the building occupiers. A buffer tank provides additional water volume (an oversized header effectively) to reduce short cycling of the heat source which improves temperature control giving a more consistent system operation. This makes the system more efficient, robust and reliable giving it greater longevity ultimately reducing maintenance requirements and saving money in the long run. A well designed buffer tank incorporated in a CHP system will offer the following functionality to improve the running of the system:

  • Provides flexibility of time separation between the heat production in the CHP unit and heat usage by the occupiers
  • Storage of heat at the system flow temperature until required by the building occupiers. This avoids short cycling of the generator for low-level demands which increases efficiency
  • Smoothes out peak heating demands (which may actually be greater than the CHP unit heat output) and minimises the required operation of any back-up gas boilers
  • Provides flexibility for the CHP system to run at advantageous times of the day to maximise benefits during high-tariff electricity periods

For system management, at Mibec we can supply all of the controls that are necessary to integrate a CHP unit with a buffer tank. In this application Heat Interface Units (HIUs) are often specified and at Mibec we offer a comprehensive range. The controls will offer the following functionality necessary to the smooth and precise running of the system:

  • All temperatures are monitored
  • System flow rates are calculated
  • CHP primary return set-point values are calculated and updated
  • Valve control parameters are adjusted
  • ΔT across the plate heat exchanger is controlled

At Mibec we are able to offer a wide range of tanks suitable for CHP from leading European manufacturers such as Cordivari. Tank sizes range from 100 litres up to 50,000 litres covering a broad range of requirements. If an off-the-shelf solution can’t be found to meet your project needs then we also offer bespoke designed but cost-effective tanks up to 200,000 litres for cooling projects.All of these special Mibec tanks are custom-made to suit the exact customer requirements in terms of sizes and connections on only a 2-4 week lead time.

We offer a full free of charge specification service covering the whole of the UK, designed to support architects, specifiers or contractors. We can give you knowledgeable, yet impartial advice on selecting the right buffer tank to meet your CHP needs. Please feel free to email or call our support department on 0330 053 880 (local call rate) where one of our trained advisers will be more than happy to help you.