Waste streams of dissolved or suspended biomassic materials and of other biomasses with moisture contents above 90 % pose a real challenge to those having to propose reasonable and effective management options.  These types of waste materials are not only a headache in that sense, they are also some of the most polluting when improperly managed, with an enormous potential to harm the environment and resources that communities depend on, as are air, water and soil.  Hydrothermal processes including gasification, pyrolysis and carbonization, may show to be excellent valorization options for these waste materials, leading to products as energy carriers, chemicals and carbonaceous materials with a variety of astounding properties. Hydrothermal carbonization (HTC) has been the subject of increasing research and business ventures in the last few years.  HTC reactors for testing in the laboratory have typically been relatively complicated and out of reach, usually having the form of a calorimetric bomb reactor with ports for stirring, injecting and measuring pressure and temperature, with a state-of-the-art heat control, adding up to a fairly expensive setup, easily above $10 k.  All these reactors handle batches, and so are far from what an industrial application would suppose, where tons of material need to be processed every day in continuous streams, and large volumes at high pressures and  temperatures (hydrothermal conditions)  pose significant explosion risks and therefore high expenses in wall thicknesses and safety previsions.  We have developed a continuous hydrothermal reactor with precise flow control and temperature and pressure measurement, which can be built from materials and parts often available in laboratory environments, plus a simple oven with a fan.  The reactor has been used to carry out hydrothermal carbonizations of several materials as sugar and different wastes from coffee cherry processing, with excellent results.  COD measurements on preliminary tests show reduction of around 75% in the waste water the case of dissolved biomass, which is a good starting point.  Nearly monodisperse micrometric char spherules were obtained (1 um - 4 um), which are to be further evaluated regarding porosity and eventual uses as catalysis and controlled delivery of substances.  The reactor design and function are presented, as well as some of the results from the tests that have been conducted.

Continuous laboratory scale hydrothermal reactor for biomassic materials with high water contents

251st National Meeting (2016)

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