case studies

CHP Waste Heat Recycling delivering 452kW thermal capacity at 90°C

Application:

This application is a typical example of a waste heat recycling and repurposing application that offers a both a highly attractive increase in efficiency and a significant level of carbon reduction with very practical retrofit application but has historically not been treated as a priority.

Gas Powered Combined Heat and Power units (CHP) obviously provide a well proven and widely applied efficient means of generating both electricity and heat.

However, despite historically high levels of CHP application this method of increasing the level of CHP system efficiency via repurposing engine waste heat is overlooked.

This application demonstrates both the ease of integration and importantly the high efficiency levels of recycling the waste heat from a CHP intercooler circuit which normally rejects waste heat to air via a dry cooler.

PURE EFFICIENCY | PURE SUSTAINABILITY | PURE SAVINGS

The Pure Thermal team are well experienced in applying Heat Pumps within CHP related applications with particular focus on delivering very high temperatures with class leading effiency levels.

This application utilised the 95°C capable P range Combined Heating & Cooling (CHC) units which repurposed the 47°C intercooler inlet flow (normally treated as waste) to deliver 90°C which enables direct integration with the primary CHP output.

As with many waste heat recycling applications the CHC units here simply integrate with the existing dry cooler inlet/outlet connections to provide a very practical, but relatively significant, increase in overall efficiency when the CHP units operation is considered.

In this application the CHP system is providing primary power and heat to a large Hospital estate within Central England and has been operating effectively for over seven years. The gas engine is nominally rated with 2,050kW electric and 2,350kW thermal outputs and is configured to operate as primary duty.

Equipment Schedule:

2 x Oilon P100 ChillHeat Combined Heating & Cooling (CHC) units

  • Evaporator operating conditions: 47/40°C
  • Condenser operating conditions: 90/78°C
  • Capacity per unit 226kW with COP 3.1
  • Single Stage system
  • Twin Compressor configuration
  • Low GWP R1234ze refrigerant (GWP 1)
  • Output temperature capability to 95°C
  • High level of modulation via twin-Variable Speed Drive design
  • Flexible control interface
  • Operational flexibility to meet varying load demands

Summary:

This application is a great example of a very practical step to achieve a significant level of carbon reduction whilst being completely straightforward to design and integrate on a retrofit basis.

In practical terms the 2 x P100 Combined Heating & Cooling units (CHC) that have been applied within this project facilitate very high temperature output temperatures in the same manner as the CHP machine itself. This enables the most straightforward method of common flow integration with both primary CHP output and the CHC unit output operating in parallel.

In summary, the decision to incorporate the P100 CHC units ensured the waste heat recycling-repurposing system was able to supply the required temperature profile at the same 90°C output as the CHP.

The very high temperature capability of the P range CHC units enabled this carbon reduction focused project to proceed and take full advantage of the waste heat available, delivering a high level of performance in terms of both cost and carbon reduction.

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