Sven-Olaf Klüe has been working in the field of design, manufacture and applications of pillow plate heat exchangers worldwide for 27 years. For the past 15 years, he has focused specifically on the process-related applications of pillow plate heat exchangers in industrial applications.
Ice water cooling in dairy plants
Use of our efficient BUCO ice water systems in dairy plants
Our BUCO ice water systems are more efficient than the coil-in-tank-systems available on the market. If the old, existing coil-in-tank systems only worked with T0= -12°C, it is possible to get about 30% more power out of the compressor with the same compressor and direct cooling by means of a falling film chiller at T0= -2°C. The energy consumption of the compressor motors, however, only increases by 5%. Therefore, the existing motors can often continue to be used. Only the evaporation condensers that are predominantly used today must be enlarged.
Why Use An Ice Bank Tank as water chiller option for milk cooling?
In dairies, the first treatment of the milk (i.e. preheating, pasteurisation, etc.) is mainly carried out with plate heat exchangers. Subsequently, 2 cooling stages take place. The first stage is carried out with normal city water, the second with ice water. In many cases in the past, coil-in-tank-systems were used as ice storage for the ice water systems. The entire day‘s output was stored in ice on the pipes and defrosted when needed. Due to milk deliveries after milking at the farms, load peaks of the dairy products are thus absorbed. Nowadays, the process in a dairy looks different. There is usually a constant base load over 24 hours plus one or two longer operating phases with high power requirements.
What are Industrial Water Chillers? What is the optimal cooling, by ice in tank (ice bank) or by ice water (water chiller)?
Coil-in-tank-systems have the disadvantage of a large space requirement, a low evaporation temperature (T0= 10°C to T0= -15°C) and a large refrigerant content. The heat transfer coefficient (K-value) of these systems is very low and decreases further the thicker the ice layer grows on the pipe. Manufacturers of plate heat exchangers sell their higher evaporation temperatures (0°C) with smaller temperature differences between ice water and evaporation temperatures as an advantage of their systems. However, problems with ice formation in the channel bends of the plate heat exchangers occur time and again, especially with contaminated process water in these closed units. From experience, we know about the degree of contamination of dairy process water in most plants, especially if they are older. A high degree of control with flow switches and hot gas injection make the system complex and susceptible to permanently safe operation in order to eliminate or minimise the risk of freezing in the plate heat exchangers.
Why does dairy use Ice Building Tank? What are its benefits? An ice bank as cooling device or a direct water chiller?
In steps of optimisation of ice water plants, a combination of direct cooling with a water chiller and ice storage from chip ice makers in one plant is the design of today‘s industrial milk cooling. A combination of direct cooling using falling film chillers and ice production using ice bank silos is a proven and more energy-efficient solution. Depending on the space available on site, both rectangular containers and cylindrical silos with small space can be used. An alternative combination of direct cooling by means of a falling film chiller and ice production by means of ice bank silos is also a proven and more energy-efficient solution by building a falling film chiller on top of existing ice storage as a pre-cooler to increase the capacity of the ice water system and has helped to cool with great effect and small investment in this industry.
The main part of the load profile (kWh per hour over a 24-hour day) is gradually handled more favourably in terms of energy by a falling film chiller, which is switched on and off. Only the peak loads are met by the ice bank system or ice bank silo, which is also operated more favourably (T0= -8°C) than a conventional coil-in-tank ice storage (T0= -10°C to -15°C), apart from the disadvantageous space needed with coil-in-tank units with enormous tanks. The advantage of BUCO falling film chillers, ice bank systems and ice bank silos is their open design, which is accessible for cleaning, and is made entirely of stainless steel with a reasonable storage water tank underneath. No seals need to be replaced, as is the case with plate heat exchangers, and should unforeseeable control fluctuations in the refrigeration system nevertheless occur, ice freezes on the Buco evaporators, which then defrosts again during control operation without mechanically destroying the evaporators. Fouling also does not have a serious effect with an increased risk of mechanical destruction as with the use of plate heat exchangers.
Glycol Chiller vs. Water chiller with ammonia – Why use Glycol for cooling milk? Why not cooling by ice (ice bank tank)?
In most installations, due to the approval procedure of ammonia over a certain level, such as 4-5 tonnes of ammonia, secondary refrigerants (glycols) are included into the processes to reduce the ammonia amount. Our systems of dimple plates need less ammonia than conventional coil-in-tank systems, so this aspect can be neglected. Most of the time, there is even more space for future installations due to the fact that with our systems the approval levels are far under 5 tonnes of ammonia.
The following aspects of a falling film chiller and ice bank system should be highlighted:
- Evaporator for cooling warm milk from the milking process with water cooling the ice water down to 0.5 °C.
- Water cooler unit of refrigeration technology for the fastest cooling of milk down to near freezing point.
- Efficient CO2 evaporation in milk cooling industry possible
- Extremely high cooling capacity for peak loads in milk cooling
- High efficiency due to direct cooling option in milk cooling
- Completely made of stainless steel, mandatory in milk cooling
- Easy inspection, as the evaporator system is not submerged in water
- Almost any storage tank geometry possible in the milk cooling system
- Use of existing storage tanks possible
- Production of ice or ice water for direct cooling, which is more energy-efficient.
- Ice bank storage tank for producing ice water of a temperature of 0.5°C completely made of stainless steel
- Lowest refrigerant content of this refrigeration unit
- Efficient, safe oil recirculation for cooling of this refrigeration unit
- Open, easily accessible evaporator systems for the dairy industry
- Efficient ice storage systems for milk cooling is easy to inspect and clean
- Use of existing tanks possible with these milk cooling ice storage systems
- Generate ice water to cool milk with our refrigeration ice storage system that takes advantage of cheap night-time electricity rates.
Ice water systems with a small water collection tank
Experience in industrial refrigeration has shown that if conventional coil-in-tank-systems of higher capacity are easily operated with refrigerant volumes of 4-5 tonnes of NH3 in circulation, this volume can be reduced by up to 80% when converting to BUCO ice water systems. In addition, the energy costs of the agitators installed in the pipe coil systems can also be reduced by 70%.