TRT Triplex dryer for drying FGD gypsum in India

A customer from the Indian cement industry, Kolkata-based Shree Cement Ltd., ordered a TRT 5000/8.0 Triplex dryer from Gebr. Pfeiffer.

As in many countries, the power supply from the electrical network is subject to strong fluctuations. Therefore, this customer, too, operates his own small coal-fired power plant for the cement works. Flue gas desulphurisation produces large quantities of FGD gypsum.

Up to now, the customer has used this artificially produced gypsum as an additive for cement production. The gypsum, however, has a moisture content of up to 20 %, which is why it could only be used wet or slightly dried. Also, it was only used locally in this cement works.

In the planned dryer plant the moisture of the FGD gypsum will be reduced to a residual moisture of < 2%. This reduction will allow the artificial gypsum to be processed in other cement grinding plants in future – some of which are spread across the whole of India – without the need of having to transport unnecessary weight in the form of water.

Two reasons played a key role in Shree Cement’s decision to implement the dryer plant with Gebr. Pfeiffer. Firstly, there has been a long-standing, extremely good cooperation between the two companies in the field of grinding technology for many years, which gives the customer the confidence to have found a competent partner for this innovative project. Secondly, the technical concept of the TRT Triplex dryer excels with its compact design and high efficiency. The material flows in co-current with the hot gases used for drying through the dryer. It passes through the three concentric tubes inserted into one another from the centre outwards before the dried material leaves the unit downwards and the exhaust air is led upwards to a dedusting system.

Radiation losses are minimised due to the fact that the operating temperature of the material in the outer tube is already low and the outer surface of the three-tube dryer is only about one third of other dryer systems. The energy balance is further optimised by the possibility of recycling the cleaned exhaust air as secondary air in hot gas generation.

Assisted by the skilled staff of Gebr. Pfeiffer (India) Pvt. Ltd., a subsidiary of Gebr. Pfeiffer SE, Kaiserslautern/Germany, the customer will install the 50-t/h dryer plant at the end of 2018, which is expected to go on stream in spring 2019.

It is also planned to partially calcine the gypsum. Tests conducted at the Pfeiffer test station produced positive results in this respect. Further installations in other plants are already being considered and will be tackled after successful testing of the first installation.

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