Falling-Film Chiller Process reliability to produce constant ice water near freezing point
Falling-Film Chiller or baudelot ice water cooler are mainly designed for cooling water down to 0.5°C near freezing point. In order to avoid building of ice at the panels, the suction gas pressure at the evaporator suction header has to be regulated, to keep the evaporation temperature not lower than the designed one, e. g. -3°C, as well as accordingly the water temperatures and flow. At systems used with e. g. glycol inside, the glycol inlet temperature has to be controlled.
If control fluctuations of the cooling system lead to ice formation, a layer of ice on the panels will reduce the heat transfer and reduce the cooling power of the falling film chiller. Building of ice at the panels may accure for some minutes, but there will not occur a mechanical destruction of the Falling-Film Chiller. Ice will melt automatically after raising of the temperature inside the panels within the next normal operation mode cycle. Our devices generate a maximum power reserve in production with this Falling-Film Chiller or baudelot ice water cooler at this temperature.
Low-specific and thermodynamic parameters of water to act as Ice Water are favourable
Ice water has a very good heat capacity, i.e. by contrast with other cooling agents relatively small quantities can convey a large amount of heat. In other words, achieve high cooling performance. The flow-specific and thermodynamic parameters of water are favourable, so that high heat transfer rates can be achieved. However, the freezing point of the water itself (zero point) sets crucial physical boundaries for ice water production and cooling with ice water. On the one hand, as regards the temperatures achievable in the water efforts are made to approach the zero point as closely as possible in order to exploit maximum temperature differences for the products to be chilled with ice water and to keep the temperature of the cooled product as low as possible.
On the other hand, as zero point is approached, the problems in ice water production with the attendant risk of ice formation increase. The known anomaly of water (lowest specific volume at 4°C) results in the water volume expanding when it freezes, and under certain circumstances this can cause destruction of the equipment used. Furthermore, ice formation in ice water systems with their thick layers of ice always involves considerable performance losses because the ice layer acts like insulation and greatly reduces the thermal transmission output.
Consequently ice water production calls for a technique that on the one hand brings the water temperature as close as possible to zero point, but on the other hand is not susceptible to potential ice formation.
Falling-Film Chiller in food any dairy processes
Above all, a Falling-Film Chiller or baudelot ice water cooler continuously generates ice water at 0.5 ° C without ice formation. Furthermore water near freezing is an important part of food and dairy refrigeration, to ensure the fastest possible cooling of the product due to the best possible product quality. Most noteworthy Ice water at 0.5°C can cool large produce in very short period of time. Under hygiene and thermodynamic aspects, cooling with ice water in the dairy and food processing industries can be considered as the safest and most effective method of cooling a wide range of products to the necessary low temperatures. Similarly blanching, cooling and washing processes are mainly focussed as well as mixing processes with any requirement of low temperatures while or right after mixing processes. Completely made out of stainless steel, it assures all required sanitary requirements, as the Ice water is always in contact with stainless steel parts AISI 304 or 316L or higher stainless steel grades up to titanium. There are various detailed sanitary adjustments for the standard Falling-Film Chiller due to different process requirements in use. But the appropriate adaptation can be just as good, as the information, given by the customer, concerning the application on site.
Falling-Film Chiller Method of operation
The Falling-Film Chiller consists of a distribution tray for the water at the top, a heat exchange system, a frame and a cover and a bottom collecting tank for water (optional).
Water is pumped into the distribution tray and at a controlled rate is distributed homogeneously by a
distribution through onto vertical panels in an open system. The process water flows in a thin film over the outer surface down on the panels and obtains the highets possible outside film coefficient. By highest descent speed, highest K transmission coefficients are reached. The high flow velocity ensures highly efficient heat transfer and a kind of a helpful self cleaning effect, which allows the operation with polluted liquids as well.
The open, non-pressurized water side of this Falling-Film Chiller or baudelot ice water cooler allows inspections and cleaning of dirt without disassembly in a few minutes. Experienced engineers with academic advice are responsible for the design. Individual channel design and construction for each project due to the high inside film coefficient and low pressure drop.
In the Falling-Film Chiller or baudelot ice water cooler the homogeneous falling film allows to chill water down to 0,5 °C without danger of freezing. Within industrial processes it can function as pre-chiller for industrial ice bank systems or is conected to the ice water side of a Plate Heat Exchanger. Or will be pumped directly to various food cooling processes. From the water collecting tank under the Falling-Film Chiller pumps to bring the chilled water to the desired consumption location.
If the Falling-Film Chiller is used with NH3, a de-oiling device for the system is provided as a small
suction pipe at the liquid bottom header of the system for gravity or pump operation. This is standard
for NH3 and done on request for CO2. With refrigerant NH3, and depending on the oil probably as well for CO2, there are severe miscibility gaps or solubility gaps with different oils, even if helpfull additives are used. Prior to the de-oiling procedure the evaporator system must be out of operation for some time, to allow the oil to separate to the bottom of the system.
In case of using oil with a lower density compared to the liquid refrigerant CO2, the refrigerant has to
be evaporated completely for this deoiling function. A regular de-oiling is needed, according to the properties of the refrigerant compressor and the oil.
Falling-Film Chiller and discontinuous inlet water flow
If water with discontinuous or changing flow rate temperatures is to be cooled, there is a split-tank-design, which allows continuous operation of the evaporator, what is aspired for any refrigeration machine. The water reservoir with flow path is individually dimensioned according to the flow profile and the water temperatures. This Falling-Film Chiller or baudelot ice water cooler is designed to be robust to unexpected fluctuations in operation. Due to the exclusive processing of stainless steel, we meet all the requirements for a food-grade design of an Ice Water Falling-Film Chiller.
Falling-Film Chiller advantages
- No risk of freezing with ice water of 0.5 ° C
- Suitable for contaminated liquids (for example greywater or red water)
- Easy access to the open system
- Easy to clean
- No seals
- Enclosed design prevents product contamination
- Completely made of stainless steel, also for salt water
- Special falling film chiller versions possible
Falling-Film Chiller technical specifications
- Capacities from 10 kW to 10,000 kW
- Evaporator for all primary refrigerants (NH3, freonss, CO2) and operating modes, secondary refrigerants (Any type of Glycol) or for brine operation
- All stainless steel materials, from AISI304 up to titanium, 254-SMO, Duplex etc.
This stainless steel execution gives assurance that the chilled water is always and only in contact with stainless steeel parts and can be used directly for the use required
- Plug-in units up to 100 kW, or for on-site refrigeration systems
Falling-Film Chiller applications and benefits
- Evaporator for water cooling up to 0.5 ° C.
- Fastest cooling of food close to freezing by high efficiency
- No risk of freezing damage to food used in fresh produce, bakeries, meat, fish, seafood etc.
- Falling-Film Chiller are preferred in application of high capacities with limited ground space
- Falling-Film Chiller plates chill liquids to almost refrigerant temperature
- Ideal for cooling down milk, yoghurt and cheese cooling as well as for beer, meat, fish, vegetables and food and beverages in general
Falling-Film Chiller simple maintenance
- Comfortable access to the open system
- Easy to clean:
- open water distribution tray
- large discharge opening for the discharge of particles
- removable side panels
- open construction plate system
Falling-Film Chiller construction and dimensions example
|TYPICAL DIMENSIONS, WITHOUT TANK||L (m)||B (m)||H (m)|
|System type A||2.0||2.1||2.0|
|System type B||3.8||2.5||2.0|