PROFESSIONAL TRAINING-I

PROFESSIONAL TRAINING-I AT ASTHA POWER SYSTEM FARIDABAD DEPARTMENT OF CHEMICAL ENGINEERING

Parvesh Kumar 11001005032 B.Tech 4th yr Submitted To :

DIFFRENT DIVISONS

What is a lead-acid battery?The lead-acid battery is an electrical storage device that uses a reversible chemical reaction to store energy. Lead-acid batteries have a capacity of six or more volts, enough to power a vehicle .AdvantagesThey are durable and dependable when used correctly.They are capable of high discharge rates, which enables them to deliver the bursts of energy that are required to start an engine.They provide the greatest amount of energy per pound and have the longest life cycle in their price range.

RAW MATERIALS Lead (Pb) Lead Oxide (PbO2) Tubular Bags Separator Container Conc H2SO4

LEADIt is the main component of lead acid battery.It is used as cathode as well as anode.It is mainly of three types of alloys:Lead Selenium AlloyLead Antimony AlloyLead Tin Calcium Alloy

OXIDE PROCESSINGLead oxide is made from refined lead. The oxide is then made into a paste by mixing it with water, acid and other chemicals.It includes:Oxide productionOxide receivingOxide conveyancePaste mixingPaste mixingDuring the paste mixing process, lead oxide, water, acid, and other chemicals are blended in a mixer to form a thick paste. This Paste is used to fill lead grids.Battery AcidBattery acid could refer to any acid used in a chemical cell or battery, but usually this term is applied to describe the acid used in a lead-acid battery, such as is found in a motor vehicle.Lead battery acid is 30-50% sulfuric acid (H2SO4) in water. Usually the acid has a mole fraction of 29%-32% sulfuric acid, density of 1.251.28 kg/L and concentration of 4.25 mol/L. 9SEPARATORSeparators between the positive and negative plates prevent short-circuit through physical contact. Separators obstruct the flow of ions between the plates and increase the internal resistance of the cell.An effective separator must possess a number of mechanical properties; such as permeability, porosity, pore size distribution, specific surface area, electrical resistance, ionic conductivity.

PLATE PROCESSINGPlate processing combines the oxide paste and the grids to prepare plates for assembly into batteries.Grid PastingHydrosettingPartingEnveloping and Wrapping

Grid PastingDuring the pasting process,lead oxide paste is applied to the grid panels in a pasting machine to fill the spaces of the grid.

HydrosettingHydrosetting methods vary between battery plants, ranging from placing the pasted plate racks in the workroom to placing the racks within a temperature- and humidity-controlled room or chamber. EnvelopingEnveloping involves placing a plate (usually positive), either automatically or manually, within porous membranes.

CHARGINGIn the charged state, each cell contains negative plates of elemental lead (Pb) and positive plates of lead(IV) oxide (PbO2) in an electrolyte of approximately 33.5% v/v (4.2 Molar) sulfuric acid (H2SO4). The charging process is driven by the forcible removal of electrons from the positive plate and the forcible introduction of them to the negative plate by the charging source.Negative plate reaction: PbSO4(s) + H+(aq) + 2-e Pb(s) + HSO4(aq) Positive plate reaction: PbSO4(s) + 2H2O(l) PbO2(s) + HSO4(aq) + 3H+(aq) + 2-e DISCHARGING In the discharged state both the positive and negative plates become lead(II) sulfate (PbSO4) and the electrolyte loses much of its dissolved sulfuric acid and becomes primarily water. The discharge process is driven by the conduction of electrons from the negative plate back into the cell at the positive plate in the external circuit.Negative plate reaction(Anode Reaction): Pb(s) + HSO4(aq) PbSO4(s) + H+(aq) + 2-ePositive plate reaction(Cathode Reaction): PbO2(s) + HSO4(aq) + 3H+(aq) + 2-e PbSO4(s) + 2H2O(l)The total reaction can be written: Pb(s) + PbO2(s) + 2H2SO4(aq) 2PbSO4(s) + 2H2O(l) LEAD ACID BATTERY CONSTRUTION

BATTERY ASSEMBLYBattery assembly combines the plates container, and other parts into a functional battery. Battery charging is also an important part of assembly.

StackingGroup BurningIntercell Welding and Post BurningFormation

STACKINGAfter curing, the plates are stacked either by hand or by machine so that positive and negative plates alternate with an insulating separator in between. GROUP BURNINGAfter the plates have been stacked, they are joined with small connecting parts and burned together to form cell elements or groups. This operation is conducted either manually at a burning station or by using an automatic cast-on-strap (COS) machine.Intercell Welding and Post BurningAfter workers place all the groups in the battery case, the straps are fused together using a torch or high electrical power source. This process can also be done Through The Partition (TTP), using a case that has been punched. The connections are then welded. The units are tested and the posts are attached.21FORMATIONIn the dry charge (plate) formation process, the first step, called tacking consists of plates being placed in a tank and lead bars being welded, or "tacked" on. Battery plates are then formed (or charged) in tanks. Wet (case) formation does not include any associated lead exposures during formation because batteries are assembled and filled with acid prior to charging.

Why distilled water is used in batteries?

Because the lack of minerals in distilled water is superior to tap water. Minerals in tap water tend to adhere to the lead plates in the battery, thereby shortening a battery's life. This is why distilled water is recommended and tap water is discouraged when it comes to servicing batteries.RECYCLINGLeadacid battery recycling is one of the most successful recycling programs in the world.

Continuous improvement in battery recycling plants and furnace designs is required to keep pace with emission standards for lead smelters.