Lead tank formation

Batteries intended to be used within 2 or 3 months after manufacture are produced with lead—ealeium—tin alloys, filled with electrolyte and ready for use. In this case, the technological scheme in Fig. 2.52 is modified. The tank formation and plate drying steps are eliminated and plate curing is followed by battery assembly, the formation process being completed in the battery itself. 

In the tank formation method, the heat capacity of the tank is great and the concentration of the H2SO4 solution is low (1.06 rel. dens.), so a small quantity of paste is sulfated and less heat is generated (and at a lower rate) during the formation process. Hence, the temperature reaches a maximum after the PbO and basic lead sulfates in the surface paste layers have reacted with most of the H2SO4 solution. 

Table 14.1 Hazards and Consequences Hazards Tank T-lOO is pumped dry Consequences Loss of production for a few moments Loss of production for an extended period of time Downstream pump cavitation leading to need for maintenance Downstream pump cavitation leading to fire at the pump Air ingress leading to formation of explosive mixture in V-101...

Once the plates have been cured, they need to be electrically formed or charged before they become functional positive and negative electrodes. During formation, the positive paste is converted to brownish black lead dioxide the negative paste is converted to a soft gray lead. The cured plates can be formed before (tank formation) or after assembly (case formation) into the battery case. 

Differences in temperature and concentration can in principle lead to corrosion cell formation, but have little effect below the water line. On the other hand, they have to be taken into account in the interior corrosion of containers and tanks in relation to their service operation (see Section 2.2.4.2). Generally the action of corrosion cells can be reduced or eliminated by cathodic protection. 

Vortex formation leads to a considerable drop in mixing efficiency and should be suppressed as much as possible in practical applications to increase the homogenizing effects of mixers. The preferable method of vortex suppression is to install vertical baffles at the walls of the mixing tank. These impede rotational flow without interfering with the radial or longitudinal flow. Figure 11 illustrates such a system. 

Although the first industrial application of anodic protection was as recent as 1954, it is now widely used, particularly in the USA and USSR. This has been made possible by the recent development of equipment capable of the control of precise potentials at high current outputs. It has been applied to protect mild-steel vessels containing sulphuric acid as large as 49 m in diameter and 15 m high, and commercial equipment is available for use with tanks of capacities from 38 000 to 7 600000 litre . A properly designed anodic-protection system has been shown to be both effective and economically viable, but care must be taken to avoid power failure or the formation of local active-passive cells which lead to the breakdown of passivity and intense corrosion. 

Where feed lines have short pipe runs, where hot wells or FW tanks are of small volume, or when FW is too cold, there often is insufficient time for full DO scavenging to take place, even when using catalyzed scavengers. The inevitable result of this lack of contact time is the formation of oxygen-induced corrosion products, which by various secondary mechanisms may settle out to form permanent deposits within the boiler system. These deposits may develop in several forms (e.g., where DO removal is particularly poor, they often appear as reddish tubercles of hematite covering sites where pitting corrosion is active). Active pitting corrosion combined with the presence of waterside deposits ultimately may lead to tube failure in a boiler or other item of system equipment and result in a system shutdown. 

Thermal. Heating the solution to 60-80°C decomposes the sodium hypochlorite, albeit slowly. If the temperature is too high then this leads to the formation of chlorates via Equation 26.2. Therefore, care is required not to overheat the solution. The consequent requirement for large holding tanks and process safety issues mean that this approach is generally not favoured. 

Generally, alkoxide-derived monodisperse oxide particles have been produced by batch processes on a beaker scale. However, on an industrial scale, the batch process is not suitable. Therefore, a continuous process is required for mass production. The stirred tank reactors (46) used in industrial process usually lead to the formation of spherical, oxide powders with a broad particle size distribution, because the residence time distribution in reactor is broad. It is necessary to design a novel apparatus for a continuous production system of monodispersed, spherical oxide particles. So far, the continuous production system of monodisperse particles by the forced hydrolysis... 

The mixture is loaded out of the reactor into tank 16 to distil tetraethyllead. The tank should already be filled with ground sulfure and ferric iron chloride. Iron chloride reduces the alkalinity of the dross and improves its consistency due to the formation of the colloid solution of iron hydroxide ground sulfure is uniformly distributed through the dross, also improving its consistency and preventing clotting of lead particles. 

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