TITAN Cement converts electrostatic precipitator to hybrid filter

For about 30 years, the electrostatic precipitators (ESPs) had effectively and reliably served the TITAN Group's Kamari plant in Greece. To comply with increasingly stringent emission standards and address the challenges of rubber tyre firing, the existing ESP technology had to be either upgraded, replaced by a fabric filter (FF) or converted to a hybrid filter. TITAN and FLSmidth's Air Pollution Control unit decided on the latter as the most cost-effective option for improving environmental performance.

Hybrid filters

In a hybrid filter, the ESP collects most of the dust including the large particles, and the fabric filter removes the fine particles. The hybrid filter ensures optimum cleaning efficiency at all times. It is also cheaper to install than a new fabric filter and has lower operating costs. Since 1997, FLSmidth has supplied more than 20 hybrid filters for kilns, coolers, mills (cement and coal mills) and by-pass applications.

Convert to hybrid or install new FF?

Choosing a hybrid filter instead of an ESP or fabric filter offers several advantages - not only from an emission point of view, but also when considering the capital investment and the operating costs.

1) Emission performance:

a. Emissions from a hybrid filter are generally lower compared to a non-converted ESP

b. The hybrid filter is a barrier filter* that is active even when the ESP is de-energised.

2) Capital investment:

a. Lower investment compared to new fabric filter, because

i. Filter casing and structure, dust handling, control system etc. can be reused

ii. Higher A/C reduces number of bags, cages etc.

3) Operating costs (normal operation):

a. Approximately 99% is separated in the ESP section, which minimises the cleaning requirement in the FF part and reduces the consumption of compressed air.

b. The total power consumption of the ESP rectifier set and the FF fan is normally lower than that of the fan for a conventional fabric filter which has to handle the total dust load.

Converting TITAN Kamari's ESP at kiln line 2

TITAN Kamari's existing raw mill filter was an ESP supplied by FLSmidth in 1977. Initially, TITAN was interested in replacing the ESP with a new fabric filter. However, to minimise downtime of the cement kiln and due to space limitations, the only realistic option was to convert the ESP to a hybrid filter. The whole operation took three weeks.

Performance data

Flow: 620,000 m3/h, combined mode, coal mill out
Temperature: 118 degrees C
Emission: <10 mg/Nm3
Pressure drop flange to flange: 80-85 mm WG
ESP part
Voltage: 34 kV
Current: 170 mA

FF part
Filtration area: 7,239 m2
Cleaning pressure: 2½ bar g.

Compared to a new fabric filter, the new hybrid filter including duct, fan, stack and installation cost 1 million euro less in initial investment. Besides, a hybrid filter results in a ~40 % power saving. So both from a capital investment point of view and when considering the operating costs, the hybrid filter proved a wise choice at TITAN Kamari.