Chick hatchery replaces natural gas boiler with efficient high-temperature heat pump
For just over a year, the Van Hulst chick hatchery in Veldhoven (Netherlands) went completely without natural gas. Two-stage heat pumps now supply the heat and cooling needed to maintain the temperature of the chicken eggs. The new solution is climate-friendly, thanks to the use of natural refrigerants and operation with solar electricity – and lowers energy costs by approx. 30,000 euros per year.
Cees Horrevorts, General Manager of the Van Hulst chick hatchery, doesn't take half-measures. When investments are needed, they should be sustainable, long-lasting and environmentally friendly. This principle was applied when the old heating system had to be replaced. The worn-out natural gas boilers (2 x 220 kW) had to be replaced with new, climate-friendly technology. At the same time, an increase in capacity was required to prepare for a facility expansion: Today around 1.1 million eggs are hatched each week and the output was planned to increase in the medium term to over 1.4 million eggs per week.
We wanted a modern solution that would meet future requirements, that we can use for a long time, and that is as climate-friendly as possible,"says Horrevorts.
A heat pump was the solution; one with natural refrigerants with low global warming potential (GWP).
Horrevorts found the ideal partner for his plans: Servex Koel- en Vriestechniek B.V. from the Dutch city of Heibloem. Servex has over 40 years of experience in building refrigeration systems and began to specialise in systems with natural refrigerants about five years ago. The company was already familiar with hatcheries from earlier projects.
Innovative and unique
Despite the many reference systems with natural refrigerants that Servex can provide, every project is different. Different boundary conditions, even new components, and varied capacity requirements make each system unique. Even the heat pump system for Van Hulst is unique. "It is the largest heat pump with natural refrigerants that we have ever built," reports Wil Kerkhof, who, together with his brother Marcel Kerkhof, is running the family-owned company Servex in the second generation. "Maybe it's even the largest heat pump of its kind in the Netherlands," he adds. Another special feature: It supplies heat at the unusually high level of approx. 80°C.
Van Hulst head Horrevorts explains why so much heat is needed at such a high temperature: "To hatch fresh eggs, we have to heat them up to 38 degrees Celsius in the first seven days. This is done using large central air handling systems. In addition, we need a great deal of hot water to ensure hygienic conditions in the facility."
Need for heat and refrigeration during hatching
Whereas chicken eggs need heat in the first week, they need cooling in the second and third week. During this time, the embryos in the tightly packed eggs develop so much heat that the air conditioners need to cool them down to maintain the ideal hatching temperature of 38°C. To do this, the new heat pump or the existing cold water generator supplies cool water at 14°C to the central air-conditioning plants.
Due to the simultaneous need for heat and air conditioned cold, the heat pump has a favourable energy balance, as the energy used also operates both media circuits. This alone makes it more efficient than the combination of gas boiler and cold water generator. In addition, gas boilers could only provide one kilowatt hour of thermal energy per kilowatt hour of fuel. The heat pump system, on the other hand, supplies significantly more thermal energy for every kilowatt hour of electricity used.
Increased capacity, higher efficiency
In addition to an increase in energy efficiency, Van Hulst also aimed to increase its thermal output from 440 kW to 550 kW (at 80°C flow temperature) in view of the upcoming capacity expansion. Furthermore, the customer required trouble-free operation in an extremely wide range from minus 20°C to plus 38°C ambient temperature.
We depend on reliable operation throughout the year to create the best conditions for hatching the eggs,"says Horrevorts.
"We wanted to do away with the old natural gas system, so maintaining these limits of application was very important for us."
In order to ensure the desired high availability at extreme ambient temperatures, Servex initially built a test system with low capacity using compressors from the specialist GEA Bock GmbH (Frickenhausen). "We have been working well with GEA Bock for a long time now", says Wil Kerkhof, explaining the choice of the compressor supplier.
The company has extensive experience with natural refrigerants such as carbon dioxide and propane and builds compressors with integrated oil pumps, making them ideal for the Van Hulst project."
Feasibility evaluated with the aid of the test system
The test system was intended to prove the feasibility of a two-stage heat pump for the required operating temperatures and also provide experience with the refrigerant isobutane (R600a). Whereas propane (R290) can be used in the first stage of the heat pump, the second stage had to be geared towards considerably higher condensation and evaporation temperatures – temperatures that could not be achieved with the refrigerants approved by GEA Bock at the time.
Philipp Schmid, who is responsible for application technology at GEA Bock, recalls: "Servex had set up a test system consisting of compressors that were similar to those used today in terms of gas flow and design, but which had less capacity. The HG88e compressors for hydrocarbons, which were planned for final use, were on the verge of series production. Van Hulst wanted these compressors because they offered slightly more capacity and efficiency than their HG8 series predecessors."
Lubrication tested on the test compressor
Using the two-stage test heat pump, Servex, together with its partner GEA Bock, tested whether the capacity could be maintained even at extreme temperatures, how de-icing would behave in the winter and how the compressors would perform. Propane, for which the compressors had already been approved, was used in the first stage. For the second heat pump stage, the partners selected isobutane as the refrigerant because its properties are very well suited to the high temperatures. Both refrigerants have a very low GWP value of three.
However, GEA Bock did not yet have extensive experience with isobutane. This was to be provided by the test system: "We paid particular attention to lubrication," Schmid reports. During trial operation, one oil type proved to be particularly suitable and was therefore selected for the second stage of the system installed at Van Hulst. In addition, GEA Bock modified the oil system to achieve better lubrication.
The heat pump currently in operation at Van Hulst consists of three two-stage systems, i.e. a total of six GEA Bock HG88e/3235-4 S HC compressors. The entire system is set up in containers next to the factory hall. This facilitated installation and the necessary fire protection measures, as both propane and isobutane are highly flammable. However, as the system operates unmanned and is housed in a closed container, the fire protection requirements could easily be met.
High operational reliability
In addition to the six compressors installed, Van Hulst can also request another compressor to be installed in the container so that a replacement can be carried out quickly in the event of a malfunction. An replacement has already taken place – not because of a defect, however, but to dismantle one of the second-stage compressors after a few months of operation at the GEA Bock facility. The compressor provided a positive result for the very demanding conditions.
For security reasons, the Servex team monitors the operation of the system via remote access to the control equipment. So far, the heat pump has been working flawlessly, even at record temperatures in the summer of 2018. "The only event in recent months has been a warning about oil pressure differential," says Kerkhof. This only required checking the oil level and sensor, and the system continued operating as usual.
Operation mainly under partial load
Usually only one of the three heat pump systems is in operation. Kerkhof: "Given the current heat demand, the capacity of one of the three heat pumps is sufficient to supply 80 degree-water, even at an ambient temperature of only minus ten degrees". This is similar in cooling mode: Already one heat pump is enough to supply the ventilation centres with 14°C cool water with a capacity of up to 200 kW. The three heat pumps therefore operate in alternation. The 10-year operating life contractually guaranteed by Servex should therefore be exceeded by the heat pumps.
As far as energy efficiency is concerned, it is still too early to make concrete statements. According to planning data, annual energy costs should be approx. 30,000 euros lower than in the past, as natural gas is no longer needed and the cold water generators are used less intensively. The additional costs of the heat pump system compared to new natural gas boilers will therefore be amortised within a reasonable time – especially as Van Hulst has received subsidies from the DEI programme (Duurzame Energie Initiatieven / sustainable energy initiative – a programme of the Dutch agency for companies RVO) due to the innovatory value of the system. About half of the additional investment was covered by these subsidies.
Climate-neutral operation with PV electricity
Van Hulst Managing Director Cees Horrevorts is very satisfied with the new heat pump system: "We can now completely do away with fossil fuel natural gas. Moreover, our heat pump is one hundred percent CO2-neutral, because we have recently started using solar power that we generate ourselves for its operation."
Author: Ralf Dunker, specialised journalist, Munich