High temperature heat pump (HTHP) installation project led by DETA – Nelson, New Zealand
The benefits of decarbonising industrial process heat are tangible and mounting for Alliance Group’s Nelson meat processing plant.
In collaboration with the Energy Efficiency and Conservation Authority (EECA), Alliance Group commissioned DETA to look for ways to improve its environmental footprint. As a global exporter, Alliance's processes must meet a range of requirements and processing standards, depending on the destination of the products.
Alliance Nelson uses hot water for pasteurisation to meet both EU and USA standards. The USA market requires hot water at 72 °C for 10 seconds, while EU countries prohibit chemical use sterilisation. Across its operations, hot water temperature requirements for processes range from:
82 °C+ for sterilising, and mixing to 65 °C washdown hoses
43 °C for hygiene stations
Starting with an energy audit, DETA quickly identified that the opportunities for a high temperature heat pump (HTHP) installation outweighed the short- and long-term economics of a biomass option, would allow Alliance to meet sterilisation, pasteurisation, and processing standards for their global customers, and reduce its reliance on diesel.
The initial energy audit identified that diesel contributed to 48% of total site carbon emissions. All diesel on site is used for hot water generation. DETA recommended replacing the diesel boiler with a HTHP, which would significantly reduce diesel consumption on site.
Alliance Nelson was using ammonia-based refrigeration systems, the waste heat from these systems was already pre-heating the water before it entered the diesel boiler via a de-super heater and oil cooler heat recovery. The key process changes made with HTHP installation involved integrating the HTHP within the existing heat recovery systems of the refrigeration plant. Figure 1.0 below shows the new HTHP integration.
Water enters at 16 °C, is preheated with waste energy from the refrigeration system, then enters the HTHP where it is heated to 75 °C. The heat pump selected was chosen specifically with futureproofing in mind, as it has the capacity to deliver up to 85 °C with plant improvements and changes to requirements.
From the time of the energy audit to the recommendation of the HTHP installation, DETA worked with Alliance to prepare the business case, facilitate installation, and most importantly conduct monitoring and verification post install. The decarbonisation and consumption savings achieved from the project show the impressive results.
In a media release, Alliance Group chief executive David Surveyor said, “We recognise we have to play our part and improve our environmental footprint. Our customers and consumers have high expectations for how the co-operative manages the natural environment and they also expect transparency and ethical food production. It is fantastic that the high temperature heat pump makes sound environmental sense and good business sense too.”
DETA was the first in Australasia to develop and implement HTHP solutions, and has experience across dairy, meat, wood and food processing sites. In this project the DETA team worked closely on site with Alliance staff. Integrating HTHPs into existing production layouts can be challenging, and the combination of the Alliance team site knowledge and the DETA team brownfield experience was key to the success of the project.