Gasification

Gasification

The UHTH system is essentially superior to all existing waste disposable technologies.  The core of each UHTH Plant is the worldwide, patented ultra-high temperature hydrology reactor.

This is feasible through the application of:

• Intense heat at low cost!
• New, specially developed materials which withstand high temperatures above 1250°C without corrosion or oxidation.

Ultra-high temperature hydrolysis (gasification) is the destructive distillation of an organic material. This distillation process involves the application of intense, indirect, thermal energy in the absence of oxygen that reduces the organic material 100% to a combustible gas, and the inorganic content to a non-hazardous, non-toxic, non-leachable, basalt-like residue.

The typical calorific values that can be unlocked from the organic MSW is shown in the below chart:

The UHTH Waste to Energy system utilizes ultra high temperature hydrolysis (gasification) to accomplish the destructive distillation of non-toxic, toxic, low-radiation and sludge waste material.  This distillation process involves the application of intense, indirect thermal energy in the absence of oxygen, which reduces the material to a combustible gas and a non-hazardous, non-leachable inorganic material.  Moreover the UHTH process does not have any environmental emissions and therefore it does not have a chimney or flue, meaning there is no toxic ash residue associated with most other incineration type systems.

The technical reason for no flue with a UHTH System is that UHT gasification produces a high calorific syngas in a controlled “closed circuit”.  This gas can then be used to operate a steam turbine or gas turbine.  The NOX and CO2 emissions are extremely low, NOX 2 and CO2 virtually zero, because the CO2 is converted into dirty Methanol, which is again gasified in the UHTH reactor, therefore no emissions and no flue or venting to atmosphere.

Cracking of the organic material into a low molecular combustible gas, using high temperatures in an oxygen-free environment:

The above formulas are the conversion of non-useable organic energy to a useable energetic Syngas.  This transformation only happens above a temperature of 1250°C, the result is an exceptionally clean gas.  Only at such elevated temperatures can the tar content be converted to energy, which does not result in contaminating the gas.

The pioneering efforts of Clean Carbon Conversion and its former companies have resulted in the world’s first ultra-high temperature hydrolysis (gasification) system. “Competitive” systems do not operate above 900°C suffering from various well known disadvantages, mainly the tar contamination of the gas that generally limits the commercial use.

Each UHTH unit processes approximately 25 MT of RDF per day (this depends on RDF size and type, and from that depending on the calorific value of the feed RDF, between 1000 to 1500 cubic meters of Syngas can be produced per unit/hr, dependant on the average kcal value of the RDF. For Example the below table illustrates the amount of potential Syngas and electricity from various calorific values using the UHTH process and generator package (with Off-Heat);

Average Calorific Value of RDF 500MT	Average Syngas Produced Per Day	Approx. Electricity Output (Inc. Offheat)
Kcal/KG	Cubic Meters	MW/Day
3000	469,125	860
3500	547,300	1,000
4000	625,500	1,150
4500	703,600	1,300
5000	781,800	1,440

Clearly the relationship between the quality of the calorific value of the waste and the amount of Syngas makes a huge difference to the Plants operations. The below graph shows this pictorially.

There are also important operational inputs into the RDF make-up that can help achieve good average kcal values of the RDF, resulting in higher volumes and better gas compositions by volume of the syngas. This typically would be by blending/mixing in vehicle tire crumbs into the RDF. This will substaintiallly boost RDf kcal values, and will be an important part of the plants operationl process. These vehicle tires can be hydrologised without any of the normal highly toxics being released into the atmoshpere, unlike most tire incineration processes that takes place.

The typical composition of the Syngas produced is:

Element			UHTG Syngas
Methane	CH4	Vol. %	2 - 3
Ethan	C2H6	Vol. %	2
Propane	C3H8	Vol. %	-
Nitrogen	N2	Vol. %	40 - 45
Carbon Dioxide	CO2	Vol. %	2
Hydrogen	H2	Vol.%	40 - 45
Low Heating Value	LHV	NJ / MN3 KCal/MN3	13 3,100

However some variation can be expected depending on the MSW/RDF composition. The 500 MT waste to energy Plant has a very high availability and maintainability capability, to ensure the Plant can run 365 days per year. It uses 20 x 25 MT UHTH units all working in parallel. There will one or two extra units on standby, which will allow periodic cleaning and maintenance programmes to be carried out for the 20 unit system so that the plant never shuts down for an annual maintenance requirement.

The Syngas is scrubbed using standard Acid and Caustic Soda scrubbers and the scrubbed elements could either be sold if they have intrinsic value, or re-inserted back into the front of the gasification system to be re-treated so they finally combine in a safe way to the non-leachable, non-toxic basalt sand/gravel The scrubbed Syngas is then supplied to the electrical power generator system.

 

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