Based on the importance of environmental protection issues, small and medium-sized enterprises are now using exhaust gas treatment systems to reduce the emission of hazardous waste gases. What kind of circulating pump is used in the exhaust gas treatment equipment? What kind of circulating pump is the most cost-effective in the exhaust gas treatment equipment?
Most of the general metal in nitric acid is rapidly corroded and destroyed, stainless steel is the most widely used nitric acid-resistant materials, all concentrations of nitric acid at room temperature have good corrosion resistance, it is worth mentioning that molybdenum-containing stainless steel (eg, 316, 316L) corrosion resistance to nitric acid is not only not better than ordinary stainless steel (eg, 304, 321), and sometimes even worse than. For high-temperature nitric acid, titanium and titanium alloy materials are usually used.
It is one of the most corrosive organic acids, ordinary steel in all concentrations and temperatures of acetic acid will be seriously corroded, stainless steel is an excellent acetic acid-resistant materials, molybdenum-containing 316 stainless steel can also be applied to high temperature and dilute acetic acid vapour. For high temperature and high concentration of acetic acid or containing other corrosive media and other demanding requirements, you can choose high alloy stainless steel or fluoroplastic pumps.
Steel is widely used in the following 80 ℃, 30% concentration of sodium hydroxide solution, there are many factories in 100 ℃, 75% of the following are still using ordinary steel, although the corrosion increases, but the economy is good. Ordinary stainless steel on the corrosion resistance of lye compared with cast iron has no obvious advantages, as long as the medium allows a small amount of iron admixture is not recommended to use stainless steel. For high temperature lye more titanium and titanium alloy or high alloy stainless steel 1. Sulfuric acid As one of the strong corrosive medium, sulfuric acid is a very wide range of important industrial raw materials. Different concentrations and temperatures of sulfuric acid on the corrosion of materials differ greatly, for the concentration of more than 80%, the temperature is less than 80 ℃ of concentrated sulfuric acid, carbon steel and cast iron have better corrosion resistance, but it is not suitable for high-speed flow of sulfuric acid, not suitable for use as a pump and valve materials; ordinary stainless steel such as 304 (0Cr18Ni9), 316 (0Cr18Ni12Mo2Ti) sulfuric acid medium is also limited use. Therefore, the pump and valve for conveying sulfuric acid are usually made of high-silicon cast iron (casting and machining difficulties), high-alloy stainless steel (alloy 20). Fluorine plastic has a better resistance to sulfuric acid performance, the use of fluorine lined pump (F46) is a more economical choice.
The vast majority of metal materials are not resistant to hydrochloric acid corrosion (including a variety of stainless steel materials), molybdenum-containing high-silicon iron can only be used for 50 ℃, 30% of the following hydrochloric acid. And the opposite of metal materials, the vast majority of non-metallic materials have good corrosion resistance to hydrochloric acid, so rubber-lined pumps and plastic pumps (such as polypropylene, fluorine plastic, etc.) is the best choice for transporting hydrochloric acid.
Most metals and non-metals in liquid ammonia and ammonia (ammonia hydroxide) corrosion is very slight, only copper and copper alloy should not be used.
Ordinary steel in sodium chloride solution and seawater, salt water corrosion rate is not too high, generally must be used to protect the paint; various types of stainless steel also has a very low uniform corrosion rate, but may be due to chlorine ions and cause localised corrosion, usually using 316 stainless steel It is better to use 316 stainless steel.
Methanol, ethanol, ethylene glycol, propanol, etc., ketone media have acetone, butanone, etc., ester media have a variety of methyl ester, ethyl ester, etc., ether media have methyl ether, ethyl ether, butyl ether, etc., which basically have no corrosive, commonly used materials can be suitable for the specific selection of the media should also be based on the attributes of the media and the relevant requirements to make a reasonable choice. It is also worth noting that ketone, ester, ether on a variety of rubber solubility, in the selection of sealing materials to avoid problems.
