Sulphur-Enhanced Urea Fertiliser Shell and Uhde Fertilizer Technologies develop New Process

Editor: M.A. Manja Wühr

Fertiliser producers are searching for a way to incorporate sulphur into their urea. Now Shell and Uhde Fertilizer Technologies work out a Fluid Bed Granulation Process, that enables the production of sulphur-enhanced urea fertilisers.

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Fluid bed granulation unit
Fluid bed granulation unit
(Picture: thyssenkrupp Industrial Solutions)

Essen/Germany – Shell and Uhde Fertilizer Technologies (UFT), part of thyssenkrupp Industrial Solutions, develop a process to incorporate sulphur into urea fertilisers. Therefor the partners combine UFT’s fluid bed granulation technology with Shell’s Urea-ES technology, which was introduced in May 2015. This announcement comes after the two companies successfully granulated Shell-developed Urea-ES emulsion in UFT’s fluid bed granulation pilot plant in Leuna, Germany. The aim of the project is to enable the largest urea plants in the world to produce granulated sulphur-containing urea by using Shell Thiogro’s sulphur-enhanced urea technology with UFT’s fluid bed granulation process.

“Fertiliser producers had been asking us about incorporating sulphur into their urea for a long time,” said Matthias Potthoff, Director of Uhde Fertilizer Technologies. Since 2014, Shell and UFT have been developing a partnership on Urea-ES technology. The successful pilot plant run demonstrates that sulphur-enhanced urea can be safely produced at UFT fluid bed granulation plants.

Homogeneous Distribution of Sulphur Particles

Urea-ES technology utilises Shell Thiogro patented technology to emulsify micron-sized particles of elemental sulphur evenly throughout urea, forming a homogeneous emulsion. This is in contrast to existing elemental sulphur-containing urea technologies, which typically coat urea in a layer of elemental sulphur. The microscopic size of the sulphur particles, at under 40 micrometres (μm), promotes the oxidation of the sulphur within the crop season.

The advantages of Shell’s technology have been combined with the features of UFT’s Fluid Bed Granulation Process, where the granulation mode is accretion instead of layering. The elemental sulphur liquor is finely dispersed in the urea melt before the solution is fed to the granulator. The flexibility of the UFT granulation process allows the production of Urea-ES without any significant changes. Just as in the normal urea granulation, the Urea-ES particles grow collectively through the solidification of tiny droplets on the seed material. The result is a very hard granule, far superior in quality to granules produced through layering or agglomeration-based processes. This slow accretion process is unique in permitting the water present in the urea solution to be thoroughly stripped on a continuous basis resulting in the end product having a remarkably low moisture content.

The dispersion of the sulphur in the urea results in a homogeneous distribution of micronsized sulphur particles in the Urea-ES granules. The bulk of the crystallisation heat released as the Urea-ES solidifies is removed by evaporating the water in the urea solution. This method of heat release reduces the amount of ambient air required for cooling and the evaporation is highly efficient because it takes place directly on the granule surface.