Very fine and cohesive powders belonging to Geldart Group C types are extremely difficult to fluidize and handle, due the very strong interparticle forces. Several patented techniques have been developed to effectively reduce or eliminate those interparticle forces so that Group C powders can be smoothly fluidized. In addition to a High-efficiency Ultrafine Particle Group C-Plus Fluidized Bed Reactor described here, this platform of technologies has also formed the foundation for pulmonary drug delivery and powder coating technologies listed below.
“Nano-modulation” to the Group C cohesive particles is an effective method to “adjust” or modify the flow properties of those extremely difficult-to-fluidize particles. Vigorously mixing and dispersing nano particles into Group C particles have made them easier to fluidize. Over 20 years of extensive studies have led to the development of a new type of particles, the Group C+ particles, from regular Group C particles through nano-modulation”. Such Group C-Plus particles, while maintaining the benefit of having extremely large specific surface area, also exhibit extraordinarily good fluidization quality with superiorly high bed expansion and significantly increased gas holdup in the dense phase, totally different from typical Group C fluidized beds. Testing using model reactions has shown Group C+ catalytic fluidized bed reactor (C-plus FBR), achieve a much higher reaction conversion, up to 235% of that using Group A particles. The contact efficiency for Group C+ particles is much higher, a few times higher than that for Group A particles. The greater contact efficiency is due to both larger specific surface area and higher bed expansion, providing larger gas-solid interfacial area and longer gas residence time. Conclusively, Group C+ particles with superior fluidization quality and reaction performance do have huge potential in gas-phase catalytic reactions.
Powder coating is an environmentally friendly alternative to the liquid painting process, because the emission of liquid solvent is eliminated and the overspray powder can be easily recycled. However, the quality of surface finish with the current powder coating process is limited because relatively coarse (30-50 microns) paint powders are used. Whereas studies have clearly shown that the use of ultrafine paint powders (~10-15 microns) would produce high-quality surface finishes that are currently only possible with liquid painting, ultrafine paint powders are not used because they cannot be fluidized and sprayed uniformly. Our research team has invented several new techniques (5 patents) to overcome the inter-particle forces between the ultrafine paint powders, so as to make them free flowing and therefore applicable in powder coating. New paint formulation method is also invented to further enhance the fluidity of the fine paint powders and to reduce or eliminate the orange-peel on the finished surface. With these new technologies, high-quality surface finishes such as those produced by liquid paint have been achieved with dry powder coating. In addition, it is also possible to produce a much thinner coatings, if required, than those obtained using coarser paint powders. This technology was first commercialized by an Ontario powder coating company and then a Chinese company (Fine Shine Inc. in Shanghai, (http://www.fineshine.com.cn/) and is now being adopted by many others in the industry.
A novel electrostatic direct dry powder coating process (11 patents) for pharmaceutical solid dosage forms has been developed to replace traditional aqueous and organic solvent based coating technologies. Compared to liquid coating, dry coating has the benefits of significantly reduced (70%) energy usage, shorter processing time, significant (90%) reduction in hot air handling, elimination of VOC when replacing solvent coating, complete compatibility with existing liquid coating process – only requiring minor modifications to existing liquid pan coaters. This technology has been shown to be compatible with all types of commercial coating materials approved for pharmaceutical coatings, including various functional coatings such as immediate release coating, enteric release coating, sustained release coating, and even the most difficult osmotic pump coating. It can be applied to all solid dosage forms, including tablets, pellets and beads. Successful scale-up have been demonstrated in a pharmaceutical equipment company and two new spin-off companies have been established for its commercialization.
In collaboration with several pharmaceutical industrial partners, a new technique for administering minute amounts of powdered drugs through inhalation has been developed (4 patents). Instead of delivering drugs through the human digestive system or intravenously, inhalation and diffusion of powdered drug through the lung directly into the blood stream is a much more effective, safer and painless drug delivery method. Compared to oral intake, only a small fraction of the drug is needed for each dose for pulmonary intake, since the first-pass GI (gastrointestinal) metabolism is significantly reduced. It also allows peptides that cannot be taken through the digestive system to be administered through the lung. However, for pulmonary drug delivery, drug powders have to be extremely fine (< 5 microns) and doses of those effective drugs exceedingly tiny (0.05-1.0 milligrams). Handling of those very small medicinal particles of very small quantity is extremely difficult, given the strong inter-particle forces as they lead to severe agglomeration. Using fluidization principles, we have developed a patented rotating fluidized bed dispensing device that can first uniformly suspend the fine powder in air flow and then with a controlled particle out-flow can precisely meter particle discharge to fill the small drug blisters that contain only 0.05-1.0 milligram of drugs. This provides the only dry method available for handling ultrafine drug powders in such small quantities, without the use of excipient particles (fillers) of large size. In addition, several new types of dry powder inhalers (some patented) have also been invented that can effectively deliver the ultrafine drug powder from the blister into human lungs, with an efficiency higher than any of the devices currently on the market. The new inhaler is breath driven and does not require any auxiliary power source such as propellant or compressed gas. This technology is now at the pre-clinical preparation stage applying for regulatory approvals.
The separation of desired chemicals, ions and proteins from a liquid mixture is essential for many processes in chemical, biochemical, environmental, pharmaceutical and food industries, but it cannot be achieved easily when multiple components co-exist in the streams. Although fluidized beds have many advantages, only single stage fluidized beds have been used so far, so that their advantages are compromised by not able to achieve simultaneous adsorption and desorption in the same unit. In the invented continuous multi-column fluidized bed ion exchange system, the adsorption and desorption (regeneration) are carried out separately and simultaneously in two separate but inter-connected columns in a continuous mode with the ion exchanger particles circulating between them. As an important unique feature of this system, liquid streams with unwanted components, small particulates and other contaminants can be treated directly by this system, as they can harmlessly pass the system through the particle interstitial space. The high selectivity, dynamic capacity and throughput make it an outstanding candidate for the treatment of large volume of feed with low product concentration. This technology has been licensed to a London-base company (Renix, www.renix.ca) which has marketed it as a CFIX (fluidized bed continuous ion exchange) technology and has successfully developed new applications for several industries such as food, beverage and mining industry.
Requirements of wastewater treatment to remove carbonaceous substrates, nutrients and phosphorus, has recently become increasingly more stringent worldwide, given the increasing population and environmental concerns. Biological fluidized bed systems with fixed-film process provide higher biomass process intensities, more compact bioreactor sizes, high mass transfer rate, better ability to handle shock organic loadings as well as mitigate inhibition and toxic impacts, enhanced retention of biosolids, and better sludge settling characteristics. Our new technology incorporates the fixed-film biological fluidized bed system with biological nutrient removal in a multi-column gas-liquid-solid circulating fluidized bed bioreactor (CFBBR), and has achieved simultaneous removal of organic carbon, nitrogen and phosphorus, in a very efficient manner and with very compact space requirement. The new CFBBR has two fluidized beds, running as anoxic/anaerobic and aerobic processes to accomplish simultaneous nitrification and denitrification as well as the elimination of organic nitrogen and phosphorus, with continuous liquid and solids recirculation through the anoxic/anaerobic and aerobic bed. The new CFBBR system is not only an excellent alternative for conventional activated sludge type treatment technologies but also capable of processing much higher loadings and suitable for industrial applications. A 5 ton/day pilot CFBBR wastewater treatment system and then a 50 ton/day mobile CFBBR system were successfully demonstrated between 2007-2014 in London, sponsored by a Canadian environmental company (Trojan Technology), the City of London, Ontario Centre of Excellence and Natural Science and Engineering Research Council of Canada (NSERC). Such compact and mobile commercial scale unit has the right capacity commensurating that of a subdivision or small apartment buildings. A Chinese company is also taking a license to commercialize this technology in China and has completed a 2000 ton/day demo unit in China.