Sunday, January 19, 2014

Hydrothermal liquefaction facts

Hydrothermal liquefaction refers to a process that can convert all kinds of biomasses to crude bio-oil. This crude bio oil is much similar to fossil crude oil, up to a point that a simple thermal upgrade and existing refinery technology can be employed to subsequently obtain all the liquid fuels we know and use today.

Hydrothermal liquefaction is connected with very high efficiency levels. It consumes approximately 10-15 percent of the energy in the feed-stock biomass, resulting in an energy efficiency of 85-90 percent.

The big advantage of hydrothermal liquefaction is that it accepts all biomasses from sewage, manure, wood, compost and plant material along with waste from households, meat factories, dairy production and all other similar industries.

This process is said to be the most feed-stock flexible of any liquid fuel producing process (it only consumes approximately 10-15% of the energy in the feed-stock biomass), the one connected with significantly smaller costs as compared to pyrolysis, bio-ethanol, gasification with Fischer-Tropsch.

The brand new HTL method is based on flow production, where the biomass is injected into a 400 °C pre-heated reactor, then cooked under high pressure for  around 15 minutes and afterwards quickly cooled down to 70°C. The temperature of 400°C and high pressure creates so called super critical state, neither liquid nor gas, at which it easily decomposes the biomass.

HTL method is environmentally friendly, since no harmful solvents are involved (crude HTL oil has very low oxygen, sulfur and water content), and looks to be cost-effective since the energy efficiency is very high.

The water that emanates from the HTL process has low carbon contents and can either be recycled into the process or ultimately be purified to attain drinking water quality, which is the scientific long-term goal.

The crude bio-oil coming from HTL process is storage stable, and has comparatively low upgrading requirements, due in part to a high fraction of middle distillates in the crude oil. It can be used as produced in heavy engines or it can be hydrogenated or thermally upgraded to obtain diesel, gasoline or jet-fuels by the existing refinery technologies.

It is often said that bio-oil coming from HTL process is unique because it is directly comparable to fossil crude oil as it can directly enter the existing fuel distribution network for automotive transportation in any concentration.

HTL process isn't „upgrading intensive# as this is the case with some other similar processes such as pyrolysis which needs immediate upgrading in order not to deteriorate.

Crude HTL oil is said to have high heating values of approximately 35-39 MJ/kg.

The most notable hydrothermal liquefaction comes from the Denmark, with Aarhus and Aalborg University leading the way on HTL research at all levels.

No comments: