LOW COST SYSTEM FOR POLLUTION CONTROL IN VERTICAL SHAFT LIME KILN

The Indian building lime industry falls under the category of small and medium scale sector employing kilns of capacities generally up 10 TPD. The present kiln produces some pollutants, and reduction in pollution of the environment is the basic need of the present time. Several governmental bodies, pollution control boards alongwith the international environmental agencies have been pressuring on the employing of the pollution control measures in various industries. Even though lime is a low polluting industry yet suspended particulate matter (comprising kiln dust and hydrocarbon volatiles) has been identified as a major pollutant being emitted from the coal fired lime kilns. Out of various pollution control devices i.e. internal separators, dry and scrubbing system, fabric filters electrostatic precipitators, and ec. a system incorporating  double deck packed bed scrubber cum entertainment separator was developed at CBRI, Roorkee (U.P)

APPLICATIONS:

Removal of pollutants such as suspended particulate matter and organic tarry matter from gaseous emission of the lime kiln.

MARKET:

To be installed at several place in the lime manufacturing centres and sensitive areas to the country.

PROCESS:

The device consists of two fixed-bed chambers containing lime stone packing. The lower one serves as the counter current gas-liquid (water) scrubber. The entering liquid through spraying nozzles distributed uniformly over the top of the packing surface. The liquid descends through the column in the form of the film distributed over the packing surface and the exhaust gas from the masonry lime kiln rises through the voids between the packing particles.

Consequently a large amount of contact surface becomes available resulting in efficient and economical mass transfer operations. The upper bed works as demister vis-à-vis entertainment separator for the revival of moisture and tarry vapours from the up flowing fan installed at the bottom of the stack.

Water from spray is conveyed through a centrifugal pump. A reservoir for storage of water has been provided. The water scrubbed material from the bottom of the lower chamber is collected into slurry tank provided adjacent tot he water tank. In order to reduce the consumption of water, the overflowing liquid from the top of the slurry tank directly falls into the water tank for reuse. Lime stone lumps packed into both the chambers can be replaced at regular intervals of time normally in about a week or so. These lime stones are recycled into he lime kiln for calcination.