This type of plant is being offered typically for the customers who are having repetitive components and having large volumes. Based on the geometry/size, we design the number of nozzles, type of nozzles and number of risers. This type of plant is very simple in nature. Depending on the chemical supplier, the numbers of process/tanks are decided. The tanks are made out of 3.15 -5.0 mm thick HR sheets. Our tank design will have minimal reinforcement; whereas strength of the tank has been taken care by formed sheets. In the cases where, SS tanks are opted, then we restrict to 3.0mm thick SS either SS-304 or SS-316 depending on the chemical supplier.
Here we cannot propose de-rusting process. but after phosphate process tank, the rinse tank will have FRP/PP lining. We have several options of heating system for the pre-treatment tanks. The following are the same. (a)Direct bottom fitted HSD / LPG fired heating system. (b) pressurized hot water system with piping inside the tank (c) Electrical heating system (d) Plate heat exchangers and (d) Developing the latest hybrid solar heating system.
In case of phosphate, we prefer to have tank in tank-heating system as shown below. The inner tank would be SS and the outer tanks can be MS. The material handling system would be overhead powered conveyor. The tanks are built with a facility for drainage, overflow, cascading, agitation and water inlet. The heating tanks are insulated with 48 kg/m3 rock wool with proper cladding work. These tanks are modular in nature and can be shifted to anywhere or any place. The controls are provided to control heaters/burners, automatic door and temperature.
The spray tunnel is constructed out of 1.6 mm thick SS. The tunnel is directly mounted on the tanks. As per the standard calculations, we arrive at the zone lengths. And based on the time, chemical and the geometry, we arrive at the number of riser/nozzles and type of nozzles.
There would be sufficient space between two processes zones and called as drain zone. If the drain zone is exordial more, then we shall provide water mist spray to avoid drying of components. Slopes provided between two process tanks and 2/3 of the slope will be towards parent tank. The tunnel panels are bolted type and mating part is protected against leakages.
There would be a fume extraction unit at the entry and exit to take out the mist.
Overall our design suits the chemical supplier and is of international standards.