A Ve n t u re o f C a p t. A n i l K. Ve r m a. Air Pollution Control Device for Lead Acid Battery Manufacturing Units

Transcription

1 A Ve n t u re o f C a p t. A n i l K. Ve r m a Air Pollution Control Device for Lead Acid Battery Manufacturing Units

2 The matter was conceived and written by Capt. Anil K. Verma.

3 Air Pollution Control Device for Lead Acid Battery Manufacturing Units About Battery Manufacturing Lead Acid Battery manufacturing consists of various stages which broadly involve (after producing or receiving lead oxide): Ÿ Paste Mixing Ÿ Grid Casting Ÿ Grid Pasting & Curing Ÿ Hydrosetting, parting & enveloping Ÿ Stacking, grouping & intercell welding Ÿ Formation Exposure of workmen to lead during all or any of the processes outlined above exceeds the prescribed standards if appropriate equipment in this respect is not installed at any Battery Manufacturing Unit. All of the above processes, some more than others, involve release of lead particles or fumes into the environment. Pollution from the above processes can be grouped into two possible types, viz: i) Lead Oxide becomes airborne and there is Particulate Pollution ii) Fumes are generated and there is Gaseous Pollution While first five of the above listed broad stages fall in the ambit of particulate pollution, last one is the cause for gaseous pollution. Of those classified under particulate pollution, only Paste Mixing & Grid Pasting are the major source of the same. To control the pollution generated in these operations, suitable Air Pollution Control Device are to be installed. These are commonly also called Ventilation Systems or Fumes Extraction Systems etc. They have to be selected based on many factors which include: Ÿ Size of the operations Ÿ Physical layout of the unit Ÿ Relative location of different points of generation of pollution Ÿ Particular processes to be covered Broadly, on the basis of nature of pollutants involved, the Air Pollution Control Device can be dealing with Non-corrosive or Corrosive gas streams. They are hence, designed accordingly. Air Pollution Control Device for Particulate Pollution Small quantities of lead oxide becomes airborne easily during many stages of the battery manufacturing process. This consists of the particulate pollution that these Air Pollution Control Device (also called Ventilation Systems) seek to entrap and control. Gas streams from these processes fall under Non-corrosive category. The material of construction for this type of unit is usually mild steel. Detail of Air Pollution Control Device with functions Hoods They are provided for point source collection of flue gases as and when they are generated at different processes. They are therefore scattered through out the unit wherever the covered processes are located. Headers & Ducting They form a grid for collection & conveyance of gases collected at hoods to the treatment equipment. They run through the unit depending upon positioning of hoods.

4 Fine Filtration Device Pulse Jet based self cleaning Bag House fitted with fabric filters is provided in the system for separation of particulate matter borne in the air. Cleaned air passes through the top plenum of the Bag House where as dust collected settles at the bottom of the hopper. This is periodically cleaned. Induced Draft Fan A high efficiency negative suction centrifugal fan is provided in the system. It generates the suction for capture of flue gases at point, their conveyance and finally their release through stack after filtration. Stack A stack of adequate height is provided for release of treated air into atmosphere. Such height is stipulated by the law in force in any particular area (30m in India). Air Pollution Control Device for Gaseous Pollution Battery formation (or plate charging or battery charging, as the process is variously known) is carried out in areas or rooms or halls specifically designated for this purpose. During the formation process of the battery, sulphuric acid fumes are generated. These are to be captured and treated so as to prevent their exposure to workmen. They are corrosive in nature. Hence, the Air Pollution Control Device for these corrosive gases (also called Fumes Extraction System) is designed and manufactured in either a combination or completely of rubber lined mild steel, or fiber reinforced plastic (FRP). Equipments used in this system are Hoods They are provided for collection of flue gases at different points in the charging area. Suction velocity and volume are maintained to ensure a proper replacement ratio of air in the area covered. Headers & Ducting They form a grid for collection & conveyance of gases collected at hoods to the treatment equipment. They are placed depending upon positioning of hoods. Scrubbing Device Water based Scrubber is the device provided for scrubbing of gases generated in formation section. Gases are introduced at the side of the scrubber and as they move towards the top opening, they pass through a jet of water spray. Cleansed gases pass through a mist eliminator and escape from the top opening. Polluted water is passed through the bottom of the cone into a partitioned tank where it is neutralized, settled and re-circulated. Induced Draft Fan A high efficiency negative suction centrifugal fan is provided in the system. It generates the suction for capture of flue gases, their conveyance and finally their release through stack after scrubbing. Stack A stack of adequate height is provided for release of treated air into atmosphere. Such height is stipulated by the law in force in any particular area (30m in India). Note: Due to continuous up-gradation in technology, specified & projected values may differ in actual products

5 Flow Sheet for Air Pollution Control System for Non-corrosive particulate pollution

6 Flow Sheet for Air Pollution Control Device for Corrosive gaseous pollution

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