Installation of a Brown Field Slag Reduction Furnace: State …
195
Filter Technology
Separation of Particulate Matter
Due to the heavy metals contained in the gas, an extremely low emission limit value
totalling 0.2 mg/Nm
3 for particles is required for both filters. To allow the reliable
observance of this value, both filters have been realised as two-stage processes. The
first stage is a flat-bag filter with compressed air cleaning system, provided with
high-efficient needle felt bags. The clean gas values downstream of the first stage are
well below 1 mg/Nm
3 . In order to observe the requested limit value of 0.2 mg/Nm
3 , a
second filter stage has each been provided downstream consisting of flat-bag filters,
equipped with non-regenerative pocket-type filter units.
SO 2 —Removal
The SO 2 contained in the process gas has to be reduced to emission values
<250 mg/Nm
3 . To avoid a complex waste water treatment system that would be
necessary if wet scrubbers were used, a conditioned dry process with the injection
of Ca(OH) 2 as additive powder has been chosen for this application. The process
allows the simultaneous separation of particles, heavy metals, and acid crude gases.
It is characterized by a highly efficient separation and a residual product in dry form.
The chosen process variant is the LUEHR FILTER Conditioning Rotor—Recycle
Process. Figure 4 shows a schematic view of process which mainly comprises the
following component parts:
• Additive powder storage, dosage, and transport
• Entrained flow reactor with conditioning rotor located in the lower reaction
chamber elbow
• Flat-bag filter
• Particle re-circulation with wetting of recycled particulate.
The chosen additive powder is commercially available Ca(OH) 2 . During SO 2 -
separation, the following reactions are taking place:
Ca(OH) 2 + SO 2 → CaSO 3 + H 2 O
CaSO 3 + 1/2 O 2 → CaSO 4 (partly)
The additive powder is injected into the gas flow near the reactor. The process
particles, reaction products, and free additives carried along in the gas flow are
separated in the flat-bag filter. Prior to discharge out of the filter system, the particles
are repeatedly reintroduced into the reactor upstream filter by passing an intermediate
storage, a dosing rotary airlock valve, and a moistening mixer.
195
Filter Technology
Separation of Particulate Matter
Due to the heavy metals contained in the gas, an extremely low emission limit value
totalling 0.2 mg/Nm
3 for particles is required for both filters. To allow the reliable
observance of this value, both filters have been realised as two-stage processes. The
first stage is a flat-bag filter with compressed air cleaning system, provided with
high-efficient needle felt bags. The clean gas values downstream of the first stage are
well below 1 mg/Nm
3 . In order to observe the requested limit value of 0.2 mg/Nm
3 , a
second filter stage has each been provided downstream consisting of flat-bag filters,
equipped with non-regenerative pocket-type filter units.
SO 2 —Removal
The SO 2 contained in the process gas has to be reduced to emission values
<250 mg/Nm
3 . To avoid a complex waste water treatment system that would be
necessary if wet scrubbers were used, a conditioned dry process with the injection
of Ca(OH) 2 as additive powder has been chosen for this application. The process
allows the simultaneous separation of particles, heavy metals, and acid crude gases.
It is characterized by a highly efficient separation and a residual product in dry form.
The chosen process variant is the LUEHR FILTER Conditioning Rotor—Recycle
Process. Figure 4 shows a schematic view of process which mainly comprises the
following component parts:
• Additive powder storage, dosage, and transport
• Entrained flow reactor with conditioning rotor located in the lower reaction
chamber elbow
• Flat-bag filter
• Particle re-circulation with wetting of recycled particulate.
The chosen additive powder is commercially available Ca(OH) 2 . During SO 2 -
separation, the following reactions are taking place:
Ca(OH) 2 + SO 2 → CaSO 3 + H 2 O
CaSO 3 + 1/2 O 2 → CaSO 4 (partly)
The additive powder is injected into the gas flow near the reactor. The process
particles, reaction products, and free additives carried along in the gas flow are
separated in the flat-bag filter. Prior to discharge out of the filter system, the particles
are repeatedly reintroduced into the reactor upstream filter by passing an intermediate
storage, a dosing rotary airlock valve, and a moistening mixer.