Concrete Cooling Systems
Components of concrete cooling systems can vary depending on customer requirements, concrete mix design and/or required concrete temperatures. KTI supplies concrete cooling systems, which range from cold water systems or ice water systems up to ice plants and towards aggregate cooling systems. For very large projects, such as dams, KTI also offers the option of concrete post-cooling systems – cooling the concrete after casting.
1. Cold water plants or ice water plants
The addition of water for mixing the concrete is self-evident. At the same time, here is the first possibility to cool the concrete during the mixing process. The mixing water is pre-cooled to either 1°C or 4°C. With this a temperature reduction of about 11K can be achieved.
The Containerized Cold Water Plants of KTI (CCWP) cool water at an inlet temperature of +30 to +45 °C down to +4 °C. For lower concrete temperatures, KTI offers Containerized Ice Water Plants (CIWP), which cool water down to +1 °C. A CIWP is equipped with a special ice bank, which stores the ice water around a tube or plate evaporator. Of course, KTI offers also solutions that are designed for lower water inlet temperatures of +15 to +25 °C, such as those found in Europe or North America.
In addition to the cold water systems, KTI offers prefabricated and insulated cold water tanks. These can be installed beside or even under the cold water plants or ice water plants to save space and installation costs.
2. Flake ice plants or plate ice plants
By replacing cold water with the corresponding amount of ice a further cooling of the concrete can be achieved. In this case, a temperature reduction of another 14 °C is realised; the concrete can therefore be cooled down by a total of 25 °C.
KTI ice plants produce flake ice (FLIP) or plate ice (PLIP). A part of the cold water from the KTI cold water plants is used to produce the ice. All ice plants are pre-assembled and delivered in 40-ft-containers. A daily production of 100 tons of flake ice (FLIP) or 200 tons of plate ice (PLIP) is available in only one unit.
3. Combined plants - cold water & ice
A technical achievement of KTI are the combined plants that produce both cold water and flake ice. These are available in a single container with a daily Output up to 42 tons of ice and 176 m³ of cold water.
4. Ice storage
Just as important as the production of ice, is its storage. This allows a constant production of ice over the entire day and an immediate discharge and supply of the required amount of ice even during load peaks.
The ice storages of KTI can be used for both flake ice and plate ice and are available for up to 90 tons holding capacity. They are included with a fully automated ice rake system and automatic ice discharge system. Mobile Ice Storages (MIS) are manufactured in a heavy-duty steel frames and are available between 18 and 90 tonnes.
Semi-automatic ice storages (MIS-sa) can hold up to 23 tons and are installed in a 40-ft-container. The ice is discharged manually.
Furthermore, KTI manufactures bolted ice storages (MIS-b), which are prefabricated for quick assembly, but dismantled for transportation. This variant of ice storage is available up to a holding capacity of 250 tons.
5. Aggregate cooling
When cooling the concrete by adding cold water or even pure ice is not sufficient, the aggregates must be cooled before mixing. This can be done by both either using cold air or cooled water. Lowering the aggregate temperature by 2 °C allows the concrete temperature to be lowered by 1 °C. So the concrete can be cooled by at least another 10 °C only by aggregate cooling.
Aggregate cooling by cold air
Cooling the aggregates by air (CCAP), a large amount of cold air is blown through the silo. In particular, under difficult conditions, the cooling aggregates by cold air is an extremely effective method. In addition to saving energy, with cold air a much lower concrete temperature can be achieved than only adding cold water or ice, as this does not affect the maximum allowed water content.
The cold air flows through the silo from bottom to top and detracts heat of the aggregates. The silo can be fed with aggregates through the inlet at the top by conventional conveyor belts. As soon as the aggregates have arrived the silo outlet, they are cooled down depending on the dwell time in the silo and are ready for feeding the batching plant.
To distribute the air evenly, KTI has developed special nozzles that are permanently installed in the silo and ensure an optimal air flow around the units. Thus, an efficient utilization of the expended cooling capacity is guaranteed.
The cold air plants are built extremely compact and are available up to 1200 kW cooling capacity.
An installation of a cold air plant beside a concrete batching plant or aggregate silos can also be done later to upgrade the system. So, cold air plants offer a perfect complement or even an extension to an existing concrete cooling system.
Aggregate cooling by cold water
Aggregates can also be precooled by using cold water or ice water. This method represents a very fast method of aggregate cooling, does not require any modification of the silos and is independent of the size of the silo.
The aggregates are sprayed with cold water or ice water on a special conveyor belt, the wet belt, after the silo. Depending on the length of the conveyor belt and the corresponding dwell time of the Aggregates, they can be pre-cooled to very low temperatures. The returning water is “pre-cleaned” in a sedimentation basin and then cooled down again.
For the application of a wet belt, KTI has developed special cold water plants and ice water plants (CAC-w), which basically differ in the design from conventional cold water plants or ice water plants (CCWP, CIWP) from KTI. Special falling film coolers are used which are specially designed and produced for cooling contaminated water.
The cold water plants and ice water plants of KTI for aggregate pre-cooling with wet belt systems are available in different sizes and are especially designed and manufactured according to the requirements of our customers.
In the field of mass concrete, which is used for the construction of dams or other large structures, it is very often necessary to cool the concrete even after pouring. This makes it possible to dissipate the resulting heat of hydration from the interior of the structure and thus contributes to the achievement of the required concrete quality.
Pipelines are integrated into the concrete, through which cold or ice water flows and dissipates the heat. Here, the correct size and optimum distance of the pipes must be observed in order to dissipate the required amount of heat.
For post-cooling, the cold or ice water systems (CCWP, CIWP) of KTI need only be slightly modified. Due to the compact design of the systems, these can be shifted depending on the construction progress in order to cool various segments of the construction.
Of course, KTI has developed appropriate accessories for all systems as an integral part of the portfolio. Likewise, the accessories are always found as one of the essential components of concrete cooling systems. By adding original KTI accessories to the KTI ice plant or ice storage, every system will be upgraded and even more efficient.
One of the most important accessory sets is in regards of ice transporation and ice weighing. The handling of ice requires a lot of experience, because the behavior of ice can only hardly be foreseen for certain circumstances. On the other hand, accurate weighing of ice is crucial to achieve the required concrete quality. Therefore, KTI has done intensive developments with various partners to provide customers with high quality and reliable products.
In addition to single or double screw conveyours, which are available in different lengths, and a suitable load cells, KTI offers equipment for pneumatic transportation of ice. This enables to transport the ice over longer distances. With so-called diverter valves, several stations can be supplied with ice.