OHD - OXIDATIVE HYDROTHERMAL DISSOLUTION PROCESS
OHD Process & Application:
Thermaquatica has designed and constructed three OHD reactor systems, and regularly uses these in research activities in Carbondale, IL. Two laboratory-scale micro reactors are used for determining feed behavior and establishing basic OHD parameters such as temperature and oxidant loading.
The semi-continuous system, which typically uses a 40 mg sample size, allows oxidant flow to be delivered either continuously or as timed pulses, while a micro-scale continuous system allows for gram scale samples to be subjected to OHD where feed and oxidant are continuously delivered as two separate, continuous feed streams.
A larger, small engineering scale fully instrumented Process Development Unit (PDU), with a slurry feed stream of up to 5 kg/h, was designed and constructed to maintain steady-state control over all important variables, including pressure, temperature, mass flow rates, residence time, and mixing.
Using only water and oxygen under the right conditions, no exotic catalysts and no other solvents, the OHD process breaks down organic biomass, hard and soft coals and other organic solids into simpler compounds that can be further processed to be used as a fuel or purified and sold as fine chemicals or chemical intermediates for the production of other products including polymers.
Thermaquatica’s technology can be scaled for deployment at local or at regional levels depending on the demands and production characteristics of the particular feedstock application. This flexibility makes it possible to process a variety of feedstock as the primary raw material using OHD integrated optimally as required by local operating environments.
Process Steps:
Feed Preparation,
OHD Reactor
Primary Dewatering
Solvent Exchange
Chemicals Recovery
OHD Research Team:
John McAlister, PhD – CEO
Ken Anderson, PhD – CTO
Bia Thomas, PhD – Business Operations
Derek Perry – Process Engineer
Madhav Soti – Engineer
Converting coal into syncrude has the advantage that it can then be fed into that pipeline (almost literally), taking advantage of that experience and the vast global petrochemical infrastructure that is already in place.
The problem with that approach is that coal, especially low rank coals like Victorian Brown Coal (VBC) are not at all like oil. Their underlying chemistries are fundamentally different.
Compared to oil, VBC is low in hydrogen and very high in oxygen. As a result, trying to convert VBC into something equivalent to oil is like trying to force a square peg into a round hole – it’s an uphill battle from the start and the result isn’t going to be pretty.
VBC is, however, a very reactive material. For example, decades of experience have shown how readily it reacts with oxygen, often resulting in self-heating and even spontaneous combustion.
Recently, a promising new technology called Oxidative Hydrothermal Dissolution (OHD) has emerged that takes advantage of the coal’s inherent reactivity, and it now appears that OHD may provide a novel, environmentally friendly route to production of high value products from VBC.
OHD is a simple process. It works by reacting coal with small amounts of dissolved oxygen in moderately high temperature (200-350oC) high pressure (80-180 bar) liquid water (Figure 1).
Under these conditions, pulverized VBC reacts in a few tens of seconds, resulting in essentially complete conversion of the coal to low molecular weight products.
No exotic catalysts or solvents are required, no gaseous nitrogen or sulphur oxides are produced, the raw aqueous product – called liquor – is non-toxic (as seen by the fact that algae and fungi readily grow in it) and importantly, the process generates very little CO2.
Typically, more than 90 per cent of the original carbon can be recovered as soluble materials that can then be refined into a variety of products including: liquids that could potentially be used as transportation fuels; and chemicals that can be used to manufacture high value end products.
The major products of OHD of VBC (up to 50 per cent of the extractable organic product) are simple aromatic compounds called Vanillate and para Hydroxy Benzoate (pHB), which are derived directly from lignin, one of the major structural components of the original wood from which VBC is derived.
Vanillate and pHB, are high value materials that can be used to make synthetic polyesters that are essentially direct substitutes for polyethylene terephthalate (PET), the plastic widely used to make (for example) polyester fibers and drink bottles.
Further Plant & Process Improvement:
Collecting more data
Reactor Control System Improvement
Operating and Maintenance Procedures
Plant Availability and Converting Test Rig to Industrial Scale
Energy Requirements: Recycling materials and energy minimise
Conclusion:
OHD Process is a proven technology, there is no academically and commercially false claim regarding viability of OHD process.
There is no doubt viability of this process based on academic research and facts
OHD is using only water and oxygen under the Right Conditions
Final OHD results depend on completion of the further test.
There is no argument for OHD commercialisation near future. It is matter of time and finance
Finally OHD is research & further test programs are progressing very well with international level.
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