In a closed container, the solid-liquid mixture after crystallization is separated from the solid-liquid by the pressure difference between the front and back of the filter cake, and then the process of filtration→sizing→refiltration→resizing→filtration or press filtration→drying is completed. The initial filtration and re-filtration process after cleaning is to make the solid-liquid mixed suspension of crystallized crystals and liquid pass through the porous sintered mesh plate through press filtration or suction filtration, so that the crystals (solid particles) are intercepted in the filter medium above, while the mother liquor (liquid) is separated through the medium.
At the same time, the drying stage of the three-in-one equipment is also to heat the filter cake to quickly evaporate the moisture to achieve the drying effect. The evaporation speed is accelerated through the vacuum method in the equipment, and the evaporated moisture is taken away by adding treated nitrogen and other media, so that The material is dried faster and the drying effect is improved.
In view of the fact that the equipment will be widely used in pharmaceutical, chemical, pesticide, food and other industries, different companies will process various materials in the equipment. Therefore, the internal structure of the equipment must be able to cope with the corrosion resistance of various pharmaceutical and chemical raw materials under high temperature and high pressure. Compared with other corrosion-resistant materials, Hastelloy alloy has higher performance, and it is most suitable for the three-in-one application of filtration, washing and drying.
Commonly used are Hastelloy B (B-2, B-3) and Hastelloy C (C-22, C-276), which have high corrosion resistance in non-oxidizing inorganic acids and organic acids, such as Resistant to dilute sulfuric acid at 70°C, resistant to all concentrations of hydrochloric acid, phosphoric acid, acetic acid and formic acid, especially heat-resistant concentrated hydrochloric acid. Hastelloy is stable in caustic and alkaline solutions, and completely stable in organic media and seawater.
(2) For iron-based alloys (stainless steel)
Whether it is ordinary 300 series stainless steel (304, 316L, etc.), or austenitic stainless steel with strong corrosion resistance (904L, 254SMO, etc.), duplex steel (2205, 2507, etc.) Corrosion ability is not as good as that of nickel-based alloys (Hastelloy), and this gap in corrosion resistance is especially obvious in reducing environments, complex mixed acid environments, and solutions containing halogen ions.
(3) Active metals (titanium, zirconium, tantalum)
Although active metals (titanium, zirconium, tantalum) have very good corrosion resistance, especially titanium is widely used in China, mainly used to replace some corrosive environments that stainless steel cannot adapt to. However, titanium mainly provides protection by forming a dense oxide film, and it is easy to be corroded in an environment (flange, gasket sealing surface) with strong reducibility or high airtightness (lack of oxygen). Moreover, the application temperature of titanium can only reach 300°C.
Although zirconium and tantalum have relatively good corrosion resistance, due to their high prices, it is particularly important to point out that all active metals cannot be used in fluorine-containing environments, and their applications are limited.
(4) Nickel-based alloys
Since nickel itself has a face-centered cubic structure, its crystallographic stability enables it to accommodate more alloying elements (chromium, molybdenum, etc.) than iron-based alloys to achieve the ability to resist various environments. In addition, nickel itself has a certain corrosion resistance, especially the resistance to stress corrosion caused by chloride ions, which is unmatched by all stainless steels.
Most Hastelloy alloys can be used in a wider range of environments and temperature ranges, and are also one of the few metal materials that can resist fluoride ions. Hastelloy itself is a nickel-based alloy, but unlike ordinary pure nickel (Ni200) and Monel, it uses chromium and molybdenum as the main alloying element, aiming to improve the adaptability to various media and temperatures, and for different industry applications Specially optimized.
To sum up, the three-in-one filtering, washing and drying multifunctional equipment manufactured by Wuxi ZhangHua Machinery uses Hastelloy alloy as the main component material, which ensures the safe filtering, washing and drying of various chemical materials in the environment of high temperature, high pressure and strong corrosion, and improves the quality of the equipment. It improves the equipment tolerance and work efficiency, reduces the number of unplanned maintenance and various costs, and plays an important role in increasing production capacity and creating more profit margins for the enterprise. At the same time, it upgrades and innovates the three-in-one multi-functional equipment The development opens up new design concepts.