[nanoPost] Novel Fibre Technology to Tackle Global Warming

University UK

- Commercial membrane tubes used for VOC control generally have a ratio of membrane area-to-volume of 30–250 m2/m3. Much higher ratios (>3000 m2/m3) and efficient recovery can be achieved with molecular sieving hollow fibre devices.

- Therefore, the work to date has concentrated on developing adsorbent hollow fibres suitable for removing VOCs as well as CO2.

- Patented Technology is being commercialised

The need for effective pollution control systems

- Reducing the emission of volatile organic compounds into the atmosphere is a key issue.  According to DEFRA the UK alone emitted  1 million tonnes of volatile organic hydrocarbons (VOCs) into the atmosphere from a wide range of sources in 2004 and 150 million tonnes of CO2 (carbon equivalent) in 2005.

- Around 24,000 million tonnes of CO2 are released per year worldwide, equivalent to about 6500 million tonnes of carbon. 

- The loss of containment of volatile organic compounds (VOCs) from industrial processes into the workplace presents not only a threat to human health but also a loss of valuable resource.

- This technology addresses two major areas of concern; the development of cost effective technology for separation, and recovery of two major pollutants to the greenhouse effect, CO2 and VOCs.

Advantages of the novel technology

- The Technology has less than 5% of the energy demand of conventional thermal oxidation processes.

- Can be applied to many types of gases (VOC, H2S and CO2, etc) and processes

- Can be applied to all scales of gas throughput, allows efficient reduction in emissions,

- Cost effective recovery and reuse of the solvents

- The research has paved the way for a new generation of adsorbent fibres with low mass transfer resistance, high separation and recovery efficiencies.

- The Technology has less than 5% of the energy demand of conventional thermal oxidation processes.

- Can be applied to many types of gases (VOC, H2S and CO2, etc) and processes

- Can be applied to all scales of gas throughput, allows efficient reduction in emissions,

- Cost effective recovery and reuse of the solvents

- The research has paved the way for a new generation of adsorbent fibres with low mass transfer resistance, high separation and recovery efficiencies.

CO2 Capture Systems

- The main CO2 abatement technologies available for capture of CO2 are: (a) Absorption (both chemical and physical using solvent); (b) Adsorption (pressure swing and temperature swing); (c) Membranes; and, (d) Cryogenics.

- Techniques using solvent absorption (e.g., solvents such as monoethanolamine & MEA), have been commercially available for many years.

- However, for applications involving the treatment of dilute concentrations of CO2, such as in power generation (which is the world's single largest source of anthropogenic CO2 emissions) and combustion plants, the size, expense and inefficiency of absorption processes are major drawbacks of this technology.

Volatile Hydrocarbons

- VOC control is needed in numerous industries, from food, beverage and dairy processing, to chemical, pharmaceutical and oil/gas industries. UK alone emitted 1 million tonnes of Volatile Organic Hydrocarbons (VOCs) into the atmosphere. 

- The largest of these sources, each accounting for around 30% of the total, was solvent use and road transport.  In addition to its role in ozone formation, one of the constituents of petrol vapour is benzene, a known human carcinogen (DEFRA, Petrol Vapour Recovery Stage II Consultation Paper 2005).

- There is a drive to install, by 2010, new petrol vapour recovery systems in filling stations that process over 3.5 million litres per year.

Expertise

- Although spinning is now a well known technique, the University has developed significant expertise and equipment suitable for the use of a wide variety of fibre “recipes” to produce nano-porous fibres.

- The hollow fibre is formed when the polymer/solvent/adsorbents dope is forced through a special orifice (a spinneret) in parallel with an internal coagulant which is pumped through the inner tube of the spinneret.

- Properties of single, double, triple and quadruple layer hollow fibres have been controlled by the manipulation of the polymer type, composition/concentration and variation of the spinning parameters.

- Experience gained from previous studies has enabled optimisation of polymers, solvents, polymer/additives compositions and spinning conditions for systems suitable for both CO2 and VOC removal.

Conclusions

- The fire resistant adsorbent hollow fibre technology has many advantages over existing packed bed (Carbon and Adsorbent) systems or other low-pressure drop devices.

- The nano-pore adsorbent fibres could be tailor-made to be able to recover low volatile compounds to high boiling aromatics from petroleum vapours to many greenhouse gases such as CO2 and SO2.

- Improving the performance of existing packed bed technology or replacing cumbersome amine technology.

- The multi layer hollow fibre monolithic modules are better than that of an equivalent packed bed of adsorbents with a fraction of the pressure drop, which allows the adsorption units to be installed in ductwork/limited space without additional gas compression.

- The fibre units can be operated on an adsorption/regeneration cycle of 0.5 - 1 h (TSA cycle), which allows for a considerable reduction in the adsorbent bed size and easily regenerable with low vacuum. 

- Also much higher area-to-volume ratios can be achieved with hollow fibres (>3000 m2/m3) compared to other configurations.

Novel technologies have following properties:

The advantages offered by such hollow fibre based systems are:

High efficiency --

Fast TSA, PSA, and combination cycle –  Should be able to regenerate efficiently Vacuum, TSA (Electrically and heated N2),  and PSA or combination

Low cost manufacturing methods – many metres of fibre can be spun at any one time, and thus provision of fibre based modules will be price-competitive with existing technologies;

Lightweight and compact – enabling flexible configurations of systems to be developed suitable for space-constrained or mobile applications.

Robust – use of multi layers means that fibres are handleable and not liable to fracture. 

Operational flexibility

Economical to operate

Linear scale-up

Attrition resistant

Orientation