Mercury removal with HGR
A large percentage of natural gas reserves contain trace concentrations of mercury. Mercury removal is particularly important in the production of Liquefied Natural Gas (LNG) as the mercury can lead to corrosion of aluminium heat exchangers used in this process. HGR is the leading technology for the removal of mercury from natural gas. HGR is impregnated with sulphur which will react with the mercury and fix it within the pores of the activated carbon. HGR has numerous references including the Middle East, North Africa, Europe, Asia and the Americas.
For the removal of mercury from liquid hydrocarbons, HGR-LH can remove up to 22 times more mercury than standard activated carbon.
Gas De-sulphurisation
Several types of gases like Ethylene, Natural gas, Biogas are de sulpherised using activated carbon. SOLCARB C3 and SOLCARB KS3 are used for the removal of trace quantities of hydrogen sulphide, mercaptans/thiols and sulphides from natural gas to prevent corrosion of natural gas pipelines and as protection for steam reformer catalysts in refineries and ammonia manufacture. SOLCARB KS3 is used where oxygen is added to oxidise the hydrogen sulphide. SOLCARB KS3 is particularly suited to the treatment of natural gas after underground storage, where trace quantities of hydrogen sulphide are often present. SOLCARB C3 is used where the addition of oxygen is not possible.
Activated carbon can also be used to purify amine solutions in natural gas scrubber systems.
Carbon Dioxide Purification
In brewing during the fermentation process, sugars are converted to alcohol and carbon dioxide is liberated by the action of the yeast. The use of this CO2 to supplement the natural carbonation of the beer is prevented due to contamination with odorous hydrocarbons. However, this off-gas can be treated with activated carbon and recovered, reducing or eliminating the need to purchase outside supply.
Compressed Gas
In order to protect compressors parts and also as an aid to efficiency, activated carbon is used to remove trace lubrication oil from air streams.
Fruit Storage – Ultra Low Oxygen (ULO)
Activated carbon is used in scrubber systems to control carbon dioxide and ethylene in fruit storage facilities to prevent premature ripening or decay.
Hydrogen Purification by Pressure Swing Adsorption (PSA)
Pressure Swing Adsorption (PSA) is an excellent method of accomplishing continuous hydrogen separation (from methane/steam hydrogen reforming) or other gas separations. Regeneration of adsorbents is accomplished by counter current depressurization and by purging at low pressure with previously recovered near product quality gas. To obtain a continuous flow of product, a minimum of two adsorbers is needed, such that at least one adsorber is receiving feed gas and actually produces a product of desired purity.
Gas Storage and Delivery
With the phase out of HFCs, CFCs and greater pressure on VOC reduction, this range of carbons can provide viable alternatives for applications that release these global warmers into the environment.
The novel gas adsorption system utilises the inherent properties of an activated carbon adsorbent and its general propensity for gas storage; whereby under pressurised condition the extensively developed carbon porosity provides for greatly enhanced volume storage of either a pure gas, such as carbon dioxide or nitrogen, or a gas mixture such as air.
These carbons have been developed for use in applications such as:
- Non VOC/HFC aerosols
- Drinks carbonation and delivery
- Mobile air conditioning
- Natural and Bio gas storage
Heat pumps
Activated carbons have been successfully used in both refrigeration and heat pumping cycles. A major reason for the interest in heat driven cycles is that they offer better utilisation of primary energy. Conventional vapour compression cycles used for refrigeration, air conditioning and heat pumping use electricity to drive a mechanical compressor.
Sorption cycles do not have a mechanical compressor and need little or no mechanical work input. Consequently they have few or no moving parts. In its simplest form an adsorption refrigerator consists of two linked vessels, both of which contain refrigerant and one of which is also filled with adsorbent as shown in the picture:
Initially the whole assembly is at low pressure and temperature, the adsorbent contains a large concentration of refrigerant within it and the other vessel contains refrigerant gas (a). The adsorbent vessel (generator) is then heated, driving out the refrigerant and raising the system pressure. The desorbed refrigerant condenses as a liquid in the second vessel, rejecting heat (b). Finally the generator is cooled back to ambient temperature, re-adsorbing the refrigerant and reducing the pressure. The reduced pressure above the liquid in the second vessel causes it to boil, absorbing heat and producing the refrigeration effect. The cycle is discontinuous since useful cooling only occurs for one half of the cycle. Two such systems can be operated out of phase to provide continuous cooling.
There is international interest in the use of activated carbons within adsorption cycles to provide refrigeration or heat pumping. The technical feasibility of adsorption cycles has already been proven. The challenge is to make machines that are cost effective, which means that they must be both efficient and of high power density. This requires the use of adsorbents that have both optimised porosity characteristics and may be integrated into systems with high levels of heat transfer intensification.
A great deal of the research into Heat Pump applications has been undertaken in collaboration with the University of Warwick.