Aggregate cooling by ice water
In most cases, adding ice together with chilled water is sufficient to reach the required concrete temperature out of the mixer. However under certain circumstances it is required to cool the aggregates as well, either by air or cold water.
The fastest way of cooling the aggregates is to flood them on a belt conveyor with ice water. Depending on the aggregate sizes the aggregates can reach an average temperature of 5 °C within 1 to 8 minutes for sizes up to 80 mm. For the big sizes up to 150 mm approx. 35 minutes have to be considered.
The cooling occurs much faster in ice water than in a cold air stream. However, it is necessary to have a well functioning dewatering system installed after the flooded cooling belt. Furthermore, a subsequent settling tank is mandatory.
The most efficient and reliable water cooling system for aggregate cooling is our specially designed falling film evaporator system which can also be supplied as a completely containerized version consisting of either hot dipped galvanised tube heat exchangers or as stainless steel plate heat exchangers, which can be cleaned manually even during operation.
Ice water plants for wet belt applications
Aggregate belts are flooded by ice water. After the cooling process the water flows into a sediment basin to separate sand mud and water. By the use of huge chiller plants the water out of these basins is chilled to 1 °C.
The special design of KTI chiller plants for wet belt applications allows to cool water which consists of sediments such as sand or mud. Instead of using a shell and tube heat exchanger, KTI uses falling film evaporators. These evaporators consist of stainless steel heat exchanger plates. Water is sprayed on these plates and flows down the plates into a basin below ice water plant.
By the use of screw compressor units from BITZER or MYCOM huge capacities can be achieved. The refrigerant which we use for these applications is ammonia. This is very economical and ecological.
Ice water plants in flooded silos
Ice Water Plants equipped with a falling film evaporator are very reliable chillers. They are used for wet belt applications as well as for silo cooling.
Beside the wet belt application, it is possible to pre-cool the aggregates by flooding the aggregate silo. There are two or more silos per aggregate size. Alternatively, both silos are flooded or drained. The water which contains sediments of sand and mud is recirculated after passing a sediment basin.