Acid Regenaration Plant
When coming from the pickling line, the waste pickle liquor is first collected in storage tanks. This storage capacity allows an operation of the regeneration plant independently from the pickle line. From the storage tanks the acid is then pumped through the waste acid filters where solid particles and undissolved residues from the pickling process are filtered out of the Liquor. Afterwards, the filtered acid is sprayed into the lower stage of the exhaust cleaning column where it circulates and is used as a chlorine absorbing agent. After leaving this column the acid enters the separator of the preconcentrator system. From this separator the pickle liquor is sprayed into the preconcentrator where it is concentrated while the exhaust gas passing the preconcentrator is cooled down. The reason why the waste pickle liquor is concentrated in this way is to reduce the later consumption of energy in the spray roast reactor. This principle ensures the high efficiency of the Shivas acid regeneration plants.
The reactor is the heart of the spray roast acid regeneration plant. It is where the waste pickle liquor is evaporated completely and the iron chloride is split up into iron (Fe) and chlorine (Cl). In order to withstand the high temperatures needed for this process the reactor is lined with fire resistant bricks on the inside. An insulation on the outside prevents uncontrolled loss of heat. Burners provide the required energy, sensors control and monitor the complete process. The produced iron oxide powder is transported out of the reactor through a rotary valve mounted on the lower end of the reactor. Above it an oxide lump breaker is installed to break any possible lumps. The gases produced in the reactor, containing water vapour and hydrogen chloride, leave the reactor via the roast gas line. Before they can be washed in the following sequence of columns the gas is cleaned from the oxide dust in a cyclone installed between reactor and preconcentrator system. The so called cleaned roast gas then passes the preconcentrator where the temperature is reduced and remaining traces of the oxide dust are washed out.
For the absorption of the hydrogen chloride gas and its transformation into hydrochloric acid a sequence of two absorber columns is used. They are both fed with rinse water, absorbing the hydro chloride gas out of the gas stream. The use of rinse water also means that no neutralisation of it is required and that the acid solved in the rinse water is also led back into the process and is then used again. While the liquid leaving the absorber columns is regenerated acid that can again be used in the pickling process, the gases leaving theab sorber columns still are contaminated with traces of HCl and therefore need to be cleaned. To guarantee highest environmental standards, the Shivas spray roast regeneration system uses a two stage exhaust cleaning system. It is fed with uncontaminated water in the upper section and waste pickle liquor in the lower section.
The Shivas spray roast regeneration plants are equipped with the latest sensor and control systems, ensuring a safe, reliable, efficient and comfortable operation of the plant.