Ferrous sulfate solution refrigerating crystallization device and method

Abstract

The invention discloses a ferrous sulfate solution refrigerating crystallization device. The ferrous sulfate solution refrigerating crystallization device comprises a refrigerating machine, a refrigerating crystallizer and a heat exchange tube arranged in the refrigerating crystallizer as well as a refrigerating capacity adjusting tank, wherein a clapboard is arranged in the refrigerating capacity adjusting tank and used for dividing the refrigerating capacity adjusting tank into an A region and a B region which are communicated; a water inlet of the A region is communicated with a chilled water outlet of the refrigerating machine through a first valve; a water outlet of the A region is communicated with a chilled water inlet of the refrigerating machine; a water inlet of the B region is communicated with a water outlet of the heat exchange tube through a second valve and is also communicated with the chilled water outlet of the refrigerating machine through a third valve; and a water outlet of the B region is communicated with a water inlet of the heat exchange tube. The ferrous sulfate solution refrigerating crystallization device is characterized in that the water temperature of the B region is adjusted for ensuring that the temperature difference between incoming water and outgoing water of a heat exchange pipeline in the crystallizer in the refrigerating process is constant, i.e. the refrigerating capacity supplied to the refrigerating crystallizer is a steady state value, and therefore, the refrigerating capacity of the needed refrigerating machine is constant, the stable running of the refrigerating machine is ensured, and simultaneously ferrous sulfate in a solution can be prevented from locally supercooling and crystallizing to attach to the wall of the heat exchange tube.

Description

technical field [0001] The invention relates to the field of freeze crystallization, in particular to a ferrous sulfate solution freeze crystallization device and method. Background technique [0002] In the iron and steel industry, when sulfuric acid is used to clean the surface of steel parts, a strong acidic solution rich in ferrous sulfate will be produced. This solution loses the pickling ability due to the richness of ferrous sulfate, but it has a certain acidity and has a certain acidity. Extremely corrosive, it is strictly forbidden to discharge without treatment. The solution can be frozen and crystallized to crystallize ferrous sulfate in the solution, and then through a centrifuge to achieve solid-liquid separation, the separated liquid has a greatly reduced concentration of ferrous sulfate, and can be reused as a pickling solution after adding acid , The separated solids are ferrous sulfate heptahydrate crystals, which are sold as commercial products. This metho...

AI Technical Summary

Problems solved by technology

Since the temperature of the liquid in the crystallizer is a variable value during the freezing process (for example, from 50°C to 0°C), when the outlet temperature of the chilled water of the refrigerator is a constant value (such as -10°C), the return water temperature of the chilled water It must not be stable, so the cooling capacity of the refrigerator in the freezing process is a process from large to small, and the instability of the working condition seriously affects the service life of the refrigerator

At the same time, when the temperature difference between the freezing water temperature and the liquid temperature in the crystallizer is too large at the initial stage of freezing, it will cause partial crystallization of ferrous sulfate in the solution to adhere to the heat exchange tube wall, reducing the efficiency of the entire freezing crystallization device.

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