Sulfur granulation solutions

A strong product (i.e. low-friability) is less prone to sulfur dust generation. Minimising dust generation has positive consequences for health, safety, and environmental aspects of materials handling operations. A dry sulfur product (i.e. less than 0.5% moisture) avoids the major issues associated with sulfuric acid, which is created by bacteria over time when sulfur, water, and air are mixed. Dry product also minimises the energy consumption associated with melting the sulfur, which is the fate of most sulfur via consumption by the chemical industry.

All drum granulation processes follow the same basic principle of enlarging small particles of sulfur (called seeds) into full-size granules. The main differences in drum granulation processes come from the following:

• Single pass vs multi-pass.
• Seed generation.
• Sulfur particulate emissions scrubbing.

The differences impact important parameters such as electrical power consumption, steam consumption, emissions, and installation footprint.

The SG20 sulfur granulation system is IPCO’s newest addition to its range of sulfur processing technologies. Demand for a medium capacity drum granulator, combined with the technology of the larger SG30 (formerly known as the Sandvik/Brimrock RS-1500), have led to the development of this latest system, which is a scaled-down version of the high capacity SG30.

The process
The new technology is designed to solidify sulfur granules in the most efficient and environmentally friendly way possible. For drum granulation technologies, this means simplifying the process down to only the essential components while properly managing sulfur particulate emissions to keep them as low as possible.

The liquid sulfur is supplied to the granulation system via a heated piping system. The sulfur flow is then split into two streams, one stream to the seed generation system and the other stream to the rotating drum.

Small solid sulfur seeds (the nuclei of the granules) are generated by freezing sprays of liquid sulfur in a water tank at controlled pressures to form the desired size range. These particles settle at the bottom of the water tank and are then gently transported into the granulation drum with a screw conveyor. The drum has flights attached to its inner surface that pick up the seeds and drop them to create curtains of particles inside the drum.

The seeds are progressively enlarged to the final product size by coating them multiple times with sprays of liquid sulfur inside the drum. The temperature inside the drum is moderated by the evaporation of water, which is provided by water spray nozzles.

By the time the sulfur particles reach the end of the drum, they are within the desired product size range and are discharged onto a collecting conveyor.

A fan is used to draw a stream of air through the drum to sweep out the water vapour. Any sulfur particles entrained in the airflow are scrubbed out of this exhaust stream using a wet scrubber before the process air stream is released to the atmosphere.

The sulfur particulates captured in the wet scrubber are pumped to the same water tank that is used to generate the seed particles. Here, the recovered particles settle out and are augured up along with the seeds to be consumed in the process.

This article was originally published in the December issue of Hydrocarbon Engineering. To read the full version, sign in or register for a free trial subscription.

Written by Casey Metheral, IPCO Germany GmbH, Germany.

Read the article online at: https://www.hydrocarbonengineering.com/clean-fuels/31122018/sulfur-granulation-solutions/