ZhangHua uses Hastelloy alloy anti-corrosion material to manufacture filter, wash and dry three-in-one

2023/04/05

Why does Wuxi ZhangHua Machinery use Hastelloy anti-corrosion materials to manufacture the "three-in-one" core components of filtration, washing and drying? In the past ten years, with the rapid development of the pharmaceutical and chemical industry, in harsh corrosive environments, Hastelloy materials are more and more widely used in petrochemical, flue gas desulfurization, fluorine chemical industry, pulp and paper, aerospace applications, acidic environment and other industrial fields.
Wuxi ZhangHua Machinery Co., Ltd. has abandoned the traditional anti-corrosion materials in its "three-in-one" multi-functional equipment for filtering, washing and drying, and adopted more advanced Hastelloy anti-corrosion materials to manufacture "three-in-one" multi-functional equipment main key components. According to the main properties of the Hastelloy alloy, it can be widely used in various unpredictable and harsh environments, and the unplanned maintenance can be minimized.

At the same time, it also has good processing and welding performance, which is convenient for on-site maintenance.

The working principle of the "three-in-one" multi-functional equipment for filtering, washing and drying: 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 filtration is completed → starch washing → re-filtering → Re-sizing→filtering or press-filtering→drying and other processes. 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 also heats 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. Accelerate the drying of materials and improve the drying effect. 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 construction of the equipment must meet the corrosion resistance of various pharmaceutical and chemical raw materials under high temperature and high pressure.

Compared with other corrosion-resistant materials, Hastelloy has higher performance, and is most suitable for "three-in-one" multi-functional equipment.

Anti-corrosion materials at this stage include two types of non-metallic materials and metallic materials. Among them, the first class of non-metallic materials include ceramics, glass fiber reinforced plastics, enamel, graphite and plastics, etc., which have the advantage of almost no corrosion, but the disadvantage is that they can only be applied to 200 ° C, are not resistant to high temperatures, and cannot withstand high pressure, let alone carry out Welding operations, high maintenance costs, and only smaller equipment can be manufactured.

Therefore, it is not suitable for "three-in-one" multi-function devices at all. The second type of metal anti-corrosion materials are iron-based alloys (stainless steel), nickel-based alloys and active metals, and Hastelloy belongs to the advanced nickel-based alloys.
Hastelloy alloys are commonly used 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 properties, such as resistance to dilute sulfuric acid at 70°C, Resistant to all concentrations of hydrochloric, phosphoric, acetic and formic acids, especially hot concentrated hydrochloric acid.


Hastelloy is stable in caustic and alkaline solutions, and completely stable in organic media and seawater.
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.) The overall corrosion resistance of the 20 alloy series of copper is not as good as that of nickel-based alloys (Hastelloy). This corrosion resistance gap is especially obvious in reducing environments, complex mixed acid environments, and solutions containing halogen ions.
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 excellent corrosion resistance, due to their high price, it should be pointed out that all active metals cannot be used in fluorine-containing environments, and their applications are limited.



In comparison, nickel-based alloys have more advantages. 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, drying) multifunctional equipment developed and produced by Wuxi ZhangHua Machinery Co., Ltd. uses Hastelloy alloy as the main component material, which ensures that various chemical materials can be used in high-temperature, high-pressure, and highly corrosive environments. Safe filtration, washing, and drying are carried out under the environment, which improves the equipment's bearing limit 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. It is of great significance to upgrade, innovate and develop more multifunctional equipment in one" to occupy more pharmaceutical and chemical equipment markets.


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