Hurricanes are optimized cyclone collectors, considering how interparticle agglomeration affects particle collection efficiency
Since the first patent was issued in 1886, cyclones have been generally designed and improved by empirical means. Building a reliable efficiency prediction method is very difficult due to the modeling complexity, since these pieces of equipment handle multiphase and highly turbulent flows, and because there is an overwhelming number of prototypes that have to be built in order to confirm the effect of changing dimension ratios on cyclone performance.
Fact is that the efficiency of general cyclones is insufficient for clients' needs, especially for small particle sizes (<10 µm).
ACS has been investigating particle agglomeration in cyclones for several years. Understanding agglomeration in cyclones has helped ACS build more accurate models of collection efficiency estimation, capable of explaining why sub-micrometer particles are often captured with much higher efficiency than predicted by standard models. Indeed, fine particles tend to form agglomerates (clusters) with much higher collection efficiency than those of the primary particles. Agglomeration increases in the presence of wide particle size distributions, long residence times in the cyclone and high inlet particle concentrations. This knowledge has been incorporated into ACS numerical simulation tool - the PACyc (Particle Agglomeration in Cyclones, Chemical Engineering Journal 162 (2010) 861-876) algorithm. This has been crucial in improving the design of ACS technologies, which have demonstrated to achieve significant reduction in emissions when compared with other high efficiency cyclones.
Supported by the PACyc Model, and considering several economical and operation constraints (such as size and pressure loss), with numerical optimization it is possible to generate millions of virtual prototypes within an affordable time period, and to observe the impact of each dimension ratio on the cyclone performance.
Considering this approach as the best path to obtain truly optimized cyclones, some theories of cyclone collection and pressure loss were chosen for each application, and afterwards improved for predicting collection efficiencies for new geometries. These numerical optimization problems have resulted in many customized cyclones but also in different new families of cyclones, some of those patented, which are used for each given application.
Indeed, different industrial cases have different needs resulting in very different cyclones, for which the optimization functions may be minimizing cost, minimizing space, among others. Each cyclone family can be further fine tuned for each client in order to meet the objectives. When high efficiency is required and particles are prone to agglomerate, which includes most of the handled dusts; recent developed Hurricane MK line of cyclones (patent pending) can be a solution to achieve emissions as low as 30mg/Nm3.
Mechanical ReCyclone® MH system for PM emission control in a 8 000m3/h at 280ºC cork dust boiler.
Hurricane system to capture particles from a sawdust dryer operating in a wood pellet plant, with a flow (8,074m3/h at 110 ºC.)
Hurricane system to reduce PM from Syngas emanating from a gasifier with a 425m3/h gas flow rate at 160ºC.
Hurricane system aiming to increase the recovery of milk proteins powder after a spray dryer. It has a capacity of 92 000m3/h at 65ºC effective flow rate.
Hurricane HR cyclones to reduce particulate matter (pm) emissions under 75mg/Nm3 from a drying tower of powder milk at Nestlé ( 31 100 m3/h at 80ºC )
Emissions to Guarantee (mg/Nm3) [<80]
Expected total pressure drop (kPa) [0.9]
Measured Emissions in April/2016 (mg/Nm3) 
Guaranteed emissions (mg/Rm3dry at 7%O2) [?150]
Expected emissions (mg/m3 | mg/Rm3dry at 7%O2) [36 | 108]
Expected pressure drop (kPa | in H2O)* [1.2 | 4.8]* This pressure drop is only for the system, does not include ducts.
*measured in march 2018