HC Energia (EC - Steel and Ferroalloys)

Hurricane system for PM emission control, working as a pre-filtering solution upstream electrical power engines. The goal is to increase the life of the cartridges on the downstream filters.

  • This equipment is composed by 4 hurricane cyclones with ø375mm.
  • Expected emissions: < 10 mg/Nm3
HC Energía
Spain
2011
Bozel 2011 (EC - Steel and Ferroalloys)

Electrostatic ReCyclone® EH pilot system for particle capture from 11,300 m3/h at 150ºC flow rate, coming from a CaSi kiln.

  • The pilot system is composed by 2 Hurricane cyclones with ø1,000mm, as pre-separators and a ReCyclone EH® system at the end of the production line, with 8 cyclones + 8 recirculators with ø600mm.
Confidential
Brazil
2011
Corrugados Getafe (PR - Steel Industry)

Hurricane system designed for product recovery of fine dust obtained in a steel industry process, operating at 158,500m3/h at 165ºC. 

  • This equipment is composed by 8 hurricane cyclones with ø1,750mm installed in 2 batteries
  • System was installed to recover uncontaminated white slag powder before reaching the bag filter and reducing heavy maintenance costs of the filter
  • Efficiency: > 97 %
Corrugados Getafe
Spain
2010
Hurricane
Numerically optimized cyclones, considering particle agglomeration
Hurricane lines of cyclones can reduce emissions from electric arch furnaces to under legal emission limits in several situations and avoiding the use of bag filters.

Depending on the type steel or ferroalloy (FeSi, CaSi, etc) and on the chosen Hurricane line of cyclones, emissions from the furnace can be reduced in 70% to 80%, with high efficiency cyclones.

In processes with very high level of PM emissions or where the legal limits are very tight, Hurricane cyclones can be designed to work as high efficiency / low pressure drop pre-separators to increase the lifetime of bag filters.
  • Very high efficiencies: down to 10-20 % of the emissions of other high efficiency cyclones;
  • Low emissions, ranging from [40-150mg]/Nm3 depending on the type steel or ferroalloy (FeSi, CaSi, etc) and on the chosen Hurricane line of cyclones,
  • Custom designs (single or parallel arrangement)
  • Low pressure drop: [50 - 120] mm w. g.
  • No temperature restrictions
  • Robust construction with no moving parts
  • Near zero maintenance and downtime costs
  • Very low operating costs
  • Low investment cost
Features

1. Air with fly ash from the furnace
2. Hurricane Cyclones. (Batteries of 2, 4, 6 or 8 units )
3. Rotary discharge valve
4. Dust receiver with collected particles
5. Clean air

Note: supporting structure, insulation and ductwork are not represented
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: decreases emissions of Hurricane Cyclones by [40-60]%
  • Very low emissions, ranging from [13-53mg]/Nm3 depending on the boiler, fuel and Hurricane line of cyclones used.
  • Pressure drop: [140-180] mm w. g.
  • No temperature restrictions
  • Robust construction with no moving parts
  • Near zero maintenance and no downtime costs
  • Low operating costs
  • Pre-assembled modular system with very easy and fast installation. Batteries of 2, 4, 6 or 8 cyclones or mechanical recirculators are shipped pre-assembled in a supporting structure with or without thermal insulation.
  • Low investment costs
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: decreases emissions of a ReCyclone MH by [40-70]%
  • "Bag Filter comparable" emissions: ranging from [4-25mg]/Nm3 depending on the boiler, fuel and Hurricane line of cyclones used.
  • Pressure drop: [120-160] mm w. g.
  • Operates up to 400oC
  • Robust construction with no moving parts (no rapping mechanisms)
  • Low maintenance and downtime costs
  • Low operating costs (Electrical field power = 5 % fan power)
  • Pre-assembled modular system with very easy and fast installation. Batteries of 2, 4, 6 or 8 cyclones or electrostatic recirculators are shipped pre-assembled in a supporting structure with or without thermal insulation.
  • Reasonable investment costs
  • Not sensitive to variable flow rates
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
Steel and Ferroalloys
Steel and ferroalloys manufacturing processes involve high temperature exhaust streams, often at more than 900ºC. Typically, the gas flows from the furnace (usually electric arch type) and goes into a gas conditioning tower to cool down below 200ºC so that it can be treated by a Bag Filter. It's also common to have ESP´s as end dedusters that can be preceded by a multicyclone serving as pre-separators.

Treating these flue gases can be very maintenance demanding for bag filters and the small particle size limits the use of common low efficiency dedusters such as regular cyclones and multicyclones, as pre-separators. Bag filter failure is consequently a very common problem for clients in this industry.

Similar problems with existing dedusters occur with the recovery of slag (resulting from the fusion process in the furnace) after pneumatic transportation. Slag powder is an extremely hard material and very aggressive for common dedusters.

Client's needs include a very robust dedusting system, either serving as end-stage collector avoiding the need to cool down flue gases, or considerably decreasing the loads of aggressive material to bag filters.
Steel & Ferroalloys
Steel & Ferroalloys
Steel & Ferroalloys
Steel & Ferroalloys
Steel and Ferroalloys (electric arch furnace) | General Arrangement

The general arrangement of a steelmaking or ferroalloy plant includes a gas conditioning tower to cool the gases to under 200ºC, upstream of a Bag Filter, or a multicyclone pre-separator, upstream of an ESP.

The Median Volume Diameter (MVD) of the particles coming from the exhaust gases of an electric arch furnace are typically very fine, ranging from 0.7µm to 1.3µm, with 65% under 1µm, for most ferroalloys (FeSi or CaSi).