POLCAL - gas suspension preheater with calciner
Proven design. Tailor-made solutions. Energy consumption reduced.
The POLCAL system was developed in particular for thermal treatment of fine-grained materials, a field where we have decades of experience. Moreover, the POLCAL floating gas heat exchanger can also be employed as a preheater. This significantly increases a kiln system’s efficiency and reduces operational costs.
Feedstocks with grain sizes from 0-2 mm – and in special circumstances even up to 4 mm – are thermally treated by the gas suspension method. POLCAL gas suspension calciners consist of up to six cyclone stages arranged one above the other and a calciner riser duct for drying, preheating and (pre)-calcination of the material. The daily output ranges from 100 to 8,000 metric tons and the process temperatures can be as high as 1,200 °C. A finished product is generated with no need for an additional unit such as a rotary kiln.
One or more cyclone stages can be used for cooling. The heated air from these stages is used as secondary air in the combustion process. In the case of very moist materials a flash dryer can be installed upstream, which is beneficial for the equipment’s energy balance. Another advantage of the POLCAM system’s modular design and range of different cyclones is the high degree of flexibility in designing plants specially tailored to our customers’ requirements.
POLCAL as a preheater
We offer the possibility of using the POLCAL floating gas heat exchanger as a preheater. The flue gas from the kiln process is passed through the preheater and transfers its heat in countercurrent to the material. The installation of a preheater greatly reduces the kiln’s fuel energy consumption while at the same time making more intensive use of the kiln, i.e. making it more productive. Our preheater concepts are fine-tuned to the most varied production capacities for both new investments and plant conversions.
Natural gas, oil, coal and calorific off-gases are ideally suitable for use as fuels. Fossil fuels are usually fed into the calciner via several injection points. Installation of an additional combustion chamber is recommended for starting the operation or if the material has to be separated from direct contact with the flame for process-technological reasons. (Photo) Phosphate ore calcining plant: The ore is first comminuted in a hammer mill with shaft-type flash dryer and the dried product is then calcined in a POLCAL gas suspension thermal reactor. Cooling takes place in a multistage flash cooler.
To ensure correct dimensioning of the POLCAL system, the properties of the raw materials and fuels are tested in our central research center to ensure all the systems and plant components are optimally designed. Thanks to numerous innovative process and design details the POLCAL gas suspension preheater with calciner offers you a future-proof solution – with or without the preheater function.