Quimigal (PR - Chemicals)

Mechanical ReCyclone® MH system for chemical powder recovery (sulfanilic acid) after a 14.000m3/h at 70ºC fluidized bed dryer.

  • The system is composed by 12 hurricane cyclones and 2 mechanical recirculators. 
  • It was installed to replace a pulse jet bag filter in order to increase powder recovery
  • MVD: 17-20 µm 
  • Efficiency: 99,5-99,6 % 
  • Emissions: 40-80 mg/Nm3
Quimigal S.A.
Estarreja, Portugal
2001
Confidential (PR - Chemicals) - AZO

Single Hurricane cyclone designed for PTFE powder recovery with flowrate of 2 550m3/h at 20ºC, 2 kPa in a chemical industry. 

  • The system is composed by 1 hurricane cyclone with ø675mm
  • MVD: 4,5 ?m
  • Expected efficiency: 98,76% collection
AZO
UK
2010
Hurricane
Numerically optimized cyclones, considering particle agglomeration

Hurricane geometries maximize powder collection for each different application, while minimizing reentrainment and keeping pressure drop at reasonable levels.


These high efficiency cyclones are the output of nonconvex nonlinear problems formulated and solved after years of work in partnership with the Faculty of Engineering of Porto.


A single Hurricane is more efficient than any other known cyclone available in the market for the same pressure drop, usually resulting in less than half of the emissions of other high efficiency cyclones available.

Very high efficiencies: around 50 % of the emissions of other high efficiency cyclones
Custom designs (single or parallel arrangement)
Low pressure drop: < 100 mm w. g.
Direct product discharge avoiding product degradation and cross contamination
Break-apart construction for easy cleaning
Very smooth surface finishing to meet strict requirements
Materials of construction in 316L stainless steel
Absence of condensation with heat tracing systems
CIP (Clean in Place) cleaning systems

1. Air and Dust from Dryer or Boiler
2. Hurricane Cyclone
3. Valve
4. Collected Particles
5. Clean Air
ReCyclone MH
Optimized cyclones with mechanical recirculation

In order to obtain very high efficiencies and compliance with emission limits, an improve recirculation system has been designed to take advantage of the Hurricane cyclones. A mechanical ReCyclone®


(ReCyclone® MH) is made up of a Hurricane with a particle separator (straight-through cyclone), placed downstream of the cyclone - called the "recirculator".


The main purpose of the recirculator is to reintroduce the fine non captured particles into the cyclone after those have been driven to the outer walls of the recirculator by centrifugal forces. While this tangential gas stream is enriched in particles, the axial gas stream exhaust to the stack is clean of particles. Recirculation is achieved through an additional fan. 

Since the recirculation system only serves the purpose of dust separation (and not collection), the particles are exclusively collected in the cyclone and the need of rapping mechanisms is thus avoided. 


Efficiency increases due to recirculation and agglomeration of very small particles with larger ones coming directly from the process. A ReCyclone® MH decreases emissions of Hurricane cyclones alone by 40 to 60%. As with cyclone systems, ReCyclone® MH systems are very robust, do not have temperature limitations and do not have moving parts to be frequently changed. Finally, recirculation control provides the benefit of handling variable process flow rates.

 

The next figure exemplifies a ReCyclone® MH in stainless steel AISI 304L for particle recovery in drying process. Recirculators can be disposed vertically, as shown, or horizontally.

Very high efficiencies: around 25 % of the emissions of multicyclones
Pressure drop: [150-220] mm w. g.
Direct product discharge avoiding product degradation and cross contamination
Robust construction with abrasion resistance
Very smooth surface finishing to meet strict requirements
Materials of construction in 316L stainless steel
Absense of condensation with heat tracing systems
CIP (Clean in Place) cleaning systems
Low investment costs
Very low maintenance and downtime costs
Ability to handle variable flow rates with recirculation control

Features

1. Air and dust from boiler or dryer
2. Hurricane cyclone ( Batteries of 2, 4, 6 or 8 units )
3. Discharge valve
4. Collected Particles
5. Clean air
6. Recirculator
7. Fan

Note: supporting structure, insulation and ductwork are not represented
ReCyclone EH
Optimized cyclones with electrostatic recirculation

Recent adoption of electrostatic recirculation in the same cyclone system has successfully proven to further reduce particle emissions, even in the [1;5]µm particle size range, assuring future regulation compliance, particularly where legal limits are very tight, with the objective of bag filter redundancy.


A DC high voltage is applied in the concentrator, allowing the recirculation of very fin nanometric particles, more resistant to centrifugal forces, to the cyclone collector. 


After having been separated in the recirculator and concentrated in the recirculation flow, electrically charged fine particles are attracted by the cyclone walls, while agglomerating with larger particles entering the system, both promoting their easier capture. 

Since particles are not captured on the walls of the recirculator, contrary to ESPs, ReCyclone® systems avoid the problem of dust colmatation and condensation.

Additionally, ReCyclone® EH systems are also immune to either low or high dust electrical resistivity and the HV required power is only 10 to 15 % of that used in ESPs. Electrostatic recirculation for fine particle capture was the winner of the Portuguese Environmental Press Award in 2008 and nominee for the European Environmental Press Award 2008.

Very high efficiencies
Pressure drop: [120-180] mm w. g.
Direct product discharge avoiding product degradation and contamination
Break-apart construction for easy cleaning
Very smooth surface finishing to meet strict requirements
Materials of construction in 316L stainless steel
Absense of condensation with heat tracing systems
Clean in Place (CIP) cleaning systems
Low operation costs
Very low maintenance and downtime costs
Ability to handle variable flow rates with recirculation control

Features

1. Air with fly ash from the boiler or from the pre-separator
2. Hurricane Cyclones. (Batteries of 2, 4, 6 or 8 units )
3. Rotary discharge valve
4. Collected particles
5. Cleaned Air
6. Electrostatic recirculators.
7. Recirculation fan
8. DC High Voltage

Note: supporting structure, insulation and ductwork are not represented

Efficient recovery of active pharmaceutical ingredients (APIs), chemical substances or food powders after drying applications such as spray and fluid bed drying is frequently a problem. The same problem occurs in many milling and micronization applications.


The preferred way to recover these sensitive products is with cyclone collectors due to their direct powder capture. Unlike bag filters or wet scrubbers, cyclones minimize filter or product contamination and product cross contamination and can easily handle a wide range of operating temperature, pressure and moisture conditions.


The current problem with cyclones is their low efficiency. And therefore, when necessary, cyclones have to be complemented with expensive specialized bag filters or wet scrubbers to increase yield or to avoid emissions to the atmosphere.


Client's needs include a high cyclone system that dramatically increases powder yield, is easy to clean and is efficient enough to comply with regulatory PM emission limits, thus avoiding the use of secondary filters.

Chemicals
Chemicals
Chemicals
Chemicals

Spray Drying | General Arrangement


Usual spray drying arrangements (single point, two point and closed cycle) include a high efficiency cyclone and a bag filter.


The cyclone serves the purpose of separating and collecting the dried powder originated in the spray-drying chamber. For some chemical powders, the fraction of product escaping to the bag filter is not considered as first grade product, and thus seen as losses. The main reasons for this are contamination with filter fibers, product cross contamination and risk of heat degradation.


For fine powders with a median diameter in volume (MVD) of less than 5 µm, losses due to low cyclone efficiency can rise to more than 25 %.

Fluid Bed Drying | General Arrangement


In fluidized bed arrangements, cyclones are used to recover the fine fraction of the dried powder, collecting or returning it to the bed.
This fraction frequently has a very small particle size distribution which results in low yields in the cyclone.
Improving the efficiency is crucial both to recover first grade product and to reduce filter bag cleaning and frequent change of bags.


Client needs include a cyclone system efficient enough in order to replace the bag filter and comply with regulatory emission limits.