WASTE TO ENERGY TECHNOLOGY AND EQUIPMENT

The Technology: C6T Advanced Recycling and Energy Conversion Process

C6T Advanced Recycling and Energy Conversion Process

 

This process incorporates several innovative technologies, four of which have patents. The operating principle of this technology is to pre-process the waste to remove recyclables, non-convertible inerts and excess water, then generate an intermediate gas or liquid fuel from the incoming waste by means of pyrolysis. This intermediate fuel is cleaned and then used in engines to produce electricity.

 

Since the C6 Ireland1 Project will be receiving an RDF fuel the Project will take fuel directly into macerators which will reduce it to the appropriate size and from there to the dryers.

 

 

Simple Process Flow

Waste Receipt and Pre-Treatment (Potential phase 2 upgrade)

Waste reception will be dictated by the location of the facility and waste types and is likely to be trucks delivering various forms of waste, the most common being Municipal Solid Waste (MSW).

 

The size of the waste must be such that it can fit in the autoclaves, dryers and pyrolyzers, therefore large items such as mattresses and tires need to be reduced in size via a shredding process.

 

Sterilization

For projects taking in raw MSW, waste will pass through the autoclave, which utilizes heat, steam and pressure to sterilize the waste. There is no need to either pre-shred or open trash bags prior to loading into the autoclave as the internal agitation in this unit performs this function. The C6T autoclave process gives a very high pathogen and virus kill rate.

Note: tires, wood and certain other feedstock do not require sterilization.

 

The autoclaves are considered the elegant solution for processing raw MSW. However, the Project will be receiving only the energy fraction of MSW which will be delivered to the waste reception hall   without recyclables or contaminants (metals, glass building, rubble etc).

 

Separation of Recyclables (Potential phase 2 upgrade)

Sterilized recyclables such as glass, ferrous and non-ferrous metals are removed, and non-pyrolyzable materials such as aggregates are also removed. Depending on local market conditions, sterilized plastic can be removed either for resale, for conversion to on road diesel fuel and naphthas, or it can be used for its energy value as part of the feedstock being converted to electricity.

 

Drying

Pyrolysis feedstock is passed to the dryers. Excess moisture in the feedstock is removed before it is sent to the pyrolyzer.

Following the drying processes, waste is homogenized and reduced in size to less than 4mm. In some instances, the reduction equipment may be positioned before the dryer.

At this stage the dry, input, commonly known as Refuse Derived Fuel (RDF grade 3, or “fluff” RDF), is fuel for the pyrolyzer.

The project will be receiving RDF. However, it is anticipated that the fuel will still need to pass through a dryer to reduce moisture content before entering the pyrolyzer.

 

Pyrolysis

Pre-Conditioning: various processing treatments are carried out on the waste in preparation for pyrolysis. The process or processes required are be dependent on the nature of the waste.

Pyrolysis: Once treated, the feedstock is passed into the pyrolyzer. It uses a high temperature in the absence of oxygen to convert waste into syngas. Syngas is predominantly a mixture of methane, hydrogen and carbon monoxide.

 

Syngas Cleaning

Tars, oils, aerosols and “fines” are removed from the syngas using variable condensing temperatures and scrubbing systems. These molecules are then cycled back through the Pyrolyser to ensure they are broken down further. Tars are vitrified along with any residue, providing the heat input to the Pyrolyzer, avoiding the use of the syngas for this purpose, and increasing overall project efficiency.

 

Electricity Production

Clean syngas is passed from the pyrolyzer either directly into an engine with a generator set or using a turbine to generate electricity. The electricity generated by gas engines and/or turbines is exported to the grid.

 

Emissions Control

Combined exhaust from the dryers, pyrolyzers and engines is progressed through a regenerative thermal oxidizer, ensuring that the final exhaust discharge to atmosphere meets worldwide emissions acceptance criteria.

 

 

The Equipment: C6T Advanced Recycling and Energy Conversion Process

The main components that make up the plant are:

 

• Waste reception, with loading area and waste conveyors.

• Waste preparation including macerators and dryers.

• Pyrolysis, where pyrolyzers turn the feedstock into syngas

• Gas clean up equipment that scrubs the gas

• Electrical generation equipment where the syngas is used to power engines to generate electricity.

• The Project is a Combined Heat and Power (CHP) project. In addition to generating electricity, the processing of energy fraction material from MSW generates excess heat and warm water. These are used to power steam turbines to produce additional electricity.

• A regenerative thermal oxidizer. Exhaust from the pyrolysers, dryers and engines exit the plant after passing through a regenerative thermal oxidizer which controls emissions.

• CEMS and scada systems.

• Output handling, where recyclables and residue exiting the process are aggregated and dispatched for sale or disposal.

• Various ancillary machines and pieces of equipment such as conveyors, boilers, gasometers, etc

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The power output of the Project based upon the waste stream will be marginally less than 10MW.

The plant architecture is focused on simplicity, standardization and reliability. Each plant has a standardized layout, shown below, which results in a simple and well-organized arrangement that maximizes ease of construction and operation.

CONTINUOUS EMISSIONS MONITORING EQUIPMENT

Continuous emissions monitoring equipment (CEMs) is located on the exhaust stack, which is the sole emissions point of the plant. Emissions will conform to all local and federal regulations and standards. The CEMs monitors all contaminants and emissions as required by EPA regulations.

The CEMS operates continuously on a 24-hour basis and will include a facility for on-line monitoring of gas concentrations and provide that notifications of any out-of-tolerance indications are sent to both on and off-site staff. The CEMs equipment is subjected to an annual surveillance test. Parallel calibration with the reference methods occurs at least once every three years. Automated reports from the CEMs will be made available to EPA inspectors. Periodic measurements of non-continuously monitored pollutants and heavy metals will be undertaken in accordance with the timescales laid down by the authorities within the Environmental Permits.