Gasification and Pyrolysis

Gasification and pyrolysis are processes by which carbonaceous materials (ranging from coal and petroleum coke to biomass, municipal waste, wood chip, automotive tyres etc.) are thermally converted through high-temperature reaction with either a controlled oxygen content (considered as a reducing atmosphere and therefore without combustion) for gasification or a  zero oxygen content in the case of pyrolysis, to form a syngas (derived from synthesis gas) or SNG (synthetic natural gas). This syngas, a fuel in itself, is more energy efficient  than combusting the original feedstock as a greater calorific value is released. The syngas is also used to produce methanol, hydrogen or for the production of synthetic fuels through the Fischer Tropsch process. In addition through various other downstream processes including catalysis chemical feedstocks for intermediaries and precursors are produced as well as end of pipe prodts such as fertilisers.  

The filtration of the solid waste from a gasification and pyrolysis processes can take place at several different stages in the process and by a number of various different methods, depending on the stage in the process. The gas may be filtered:

• using either filter elements or cyclones prior to the heat exchanger at what is the highest temperature option with temperatures generally between 800°C and 1,000°C.
• using either filter elements or cyclones post heat exchanger resulting in temperatures ranging between 320°C to 650°C.
• using after significantly greater cooling  using wet scrubbing systems resulting in temperatures generally below 250°C.

Porvair Filtration Group has proven expertise in the filtration systems that operate with IGCC (Integrated Gasification Combined Cycle) gasification of coal and petroleum coke. We also design and manufacture filtration and separation equipment for processes such as PFBC (Pressurized Fluidized Bed Combustion), biomass and pelletised MSW (Municipal Solid Waste).

Porvair design and manufacture char filter packages to retain the highly abrasive and corrosive char produced during the process, in order to prevent downstream contamination that would lead to the inevitable failure of critical components.

The use of permanent metal media filtration solutions provide the filtration performance required, both in terms of separation efficiency as well as cleanability. The ability to operate in a broad range of pressure and temperature conditions whilst continuing to provide consistent performance is unparalleled by other technologies.

Other high temperature gas applications:

• Catalyst recovery
• Photovoltaic cell production
• Tyre pyrolysis
• Calcining
• Chemical production.

Metal filters in hot gas applications also provide the following benefits:

• High permeability assisting process flow and blowback operations
• Integral strength at high temperature
• Thermally resistant with transient temperature conditions
• Corrosion resistant with alloy options
• Minimal downtime in service due to inherent cleanability
• Minimal operator handling through on-site cleaning
• Consistent filtration performance with transient conditions
• Longer operational life.

Pulsejet cleaning

Given that the filtration of the syngas is a critical function to the smooth operation of the plant, the in situ cleaning is a critical operation performed on the filter to maintain the filtration function.

Delivery of the pulsejet into the filter element is achieved through the use of dedicated nozzles that are positioned above every filter element at a predetermined distance to suit the operating conditions and the size of the filter element.