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A laboratory representation of the cavitation process.
A technology aimed at upgrading heavy and sour crude oils into lighter, sweeter crudes is garnering interest in Europe. Houston-based SulphCo’s patented ultrasound Sonocracking technology is undergoing commercial-scale field trials with a European testing partner.
The Sonocracking technology is a low-pressure, low-temperature process that employs ultrasonic reactors to desulfurize and upgrade crude oil streams. The company states that the technology works by inducing cavitation in the produced fluid, a process that creates submicron-sized vapor bubbles at sites of refraction due to the negative pressure generated from the intense sound waves in the liquid.
The vapor bubbles then begin to oscillate and grow under the effect of positive pressure, and as subsequent ultrasound waves move through the liquid they stress the bubbles, leading to their eventual contraction and collapse. The bursting of these submicron- and micron-sized bubbles generates excess heat and pressure in their immediate vicinity, which SulphCo states turns each bubble into a microreactor. Temperatures and pressures reaching 5000 K and 500 atm, respectively, are estimated, conditions severe enough to cause disruption of molecular bonds.
The company employs its Sonocracking technology with an inexpensive proprietary catalyst to crude oil/water mixtures, reportedly breaking molecular bonds in the water vapor present at the center of the cavitation bubbles. Short-lived free radicals result, some of which can bring about oxidation of sulfur compounds in the crude; the company reports that a 10 to 25% reduction in sulfur levels may be expected. SulphCo also reports that the process may rupture complex hydrocarbon bonds with the result of reducing overall crude viscosity and increasing API gravity (1-3 point improvements are typical).
The company has developed closed-loop units to treat a daily capacity of 5,000 bbl per unit, and successive processing units can be added in multiples of 5,000 bbl per day (B/D).
A larger modular unit capable of processing 15,000 B/D has also been developed, which is the design currently under evaluation by SulphCo’s European partner. The unit is skid mounted and can be transported in a typical shipping container. The unit also reportedly possesses a smaller footprint compared to conventional hydrotreating equipment, and is expected to have lower capital costs as well.
The European trial follows the successful completion of full-scale field trials at a facility in the southeastern US in 2008. “We are very pleased to be recommencing commercial-scale field trials of our Sonocracking technology with our European testing partner,” said Larry Ryan, SulphCo’s Chief Executive Officer. “As soon as test results and analyses become available, we will provide an update.”
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