Correct choice of fluorine plastic pump method:
Petroleum and chemical industry occupy a very important position in the national economy. Chemical process pumps are also attracting more and more attention as a key supporting equipment. Due to the complex nature of the chemical medium, coupled with the environmental protection and equipment requirements continue to increase energy consumption, as a chemical manufacturer, how should we select the chemical pump? Should pay attention to what aspects? ... And so on is particularly important. Now combined with the majority of chemical products related to the characteristics of chemical pumps on the selection of common use to do a brief review, hoping to benefit our customers better work in this area.
First, the selection of fluorine plastic pump should consider the following questions:
1, corrosion-resistant problems: For a long time, corrosion is one of the most headache hazards of chemical equipment, a slight carelessness, ranging from damage to equipment, heavy cause accidents and even lead to accidents. According to the statistics, about 60% of the destruction of chemical equipment is caused by corrosion. Therefore, the selection of chemical pumps should first pay attention to the scientific material selection. There is often a misunderstanding that stainless steel is a "universal material," no matter what the media and environmental conditions are held out of stainless steel, which is very dangerous. The following for some common chemical media to talk about the selection of the main points:
1) Sulfuric acid: As one of the strong corrosive media, sulfuric acid is an important industrial raw material with a very wide range of uses. Different concentrations and temperatures of sulfuric acid on the corrosion of materials vary greatly, for the concentration of more than 80%, the temperature is less than 80 ℃ of concentrated sulfuric acid, carbon steel and cast iron has good corrosion resistance, but it is not suitable for high-speed flow of sulfuric acid, Not suitable for pump valve material; common stainless steel such as 304 (0Cr18Ni9), 316 (0Cr18Ni12Mo2Ti) sulfuric acid medium is also limited use. Therefore, the delivery of sulfuric acid pump valve is usually made of high silicon cast iron (casting and processing difficult), high alloy stainless steel (No. 20 alloy) manufacturing, but its processing is difficult and expensive, so people are not optimistic. Fluoroplastics alloy has very good resistance to sulfuric acid. It is the patented material of Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences. Our company introduced the patented technology in 1985 and the earliest use it to develop and produce corrosion-resistant chemical pump. After the experiment of the Chinese Academy of Sciences, No chemical medium has yet been found to react with it over the applicable temperature range, so using a fluorine-based pump (F46) is a more economical option. Company products are: CQB fluorine plastic magnetic pump, IMD lining fluorine magnetic pump, IHF lined fluorine centrifugal pump, FSB fluorine alloy centrifugal pump.
2) Hydrochloric acid: Most metal materials are not resistant to hydrochloric acid corrosion (including a variety of stainless steel materials), molybdenum high ferrosilicon can only be used for 50 ℃, 30% hydrochloric acid. In contrast to metallic materials, the vast majority of non-metallic materials have good corrosion resistance to hydrochloric acid, so lined rubber pumps and plastic pumps (such as engineering plastics, fluoroplastics, etc.) are the best choice for the delivery of hydrochloric acid. Company products are: CQB fluorine plastic magnetic pump, IMD lining fluorine magnetic pump, IHF lined fluorine centrifugal pump, FSB fluorine alloy centrifugal pump, UHB polyethylene centrifugal pump.
3) Nitric acid: most of the common metals are rapidly corroded in nitric acid, stainless steel is the most widely used nitric acid-resistant material, all concentrations of nitric acid at room temperature have good corrosion resistance, it is worth mentioning that the molybdenum-containing stainless steel ( Such as 316,316L) nitric acid corrosion resistance not only not superior to ordinary stainless steel (such as 304,321), sometimes even worse. For high temperature nitric acid, usually using fluorine plastic alloy material. Company products are: CQB fluorine plastic magnetic pump, IMD lining fluorine magnetic pump, IHF lined fluorine centrifugal pump, FSB fluorine alloy centrifugal pump.
4) Acetic acid: It is one of the most corrosive substances in organic acids. Ordinary steel will be seriously corroded in all concentrations and temperatures of acetic acid. Stainless steel is an excellent acetic acid-resistant material. Molybdenum-containing 316 stainless steel is also suitable for high temperature And dilute acetic acid steam. For high temperature and high concentration of acetic acid or other corrosive media containing harsh requirements, the choice of high-alloy stainless steel or fluorine plastic pump. Such as CQB fluorine plastic magnetic pump, IMD lining fluorine magnetic pump, IHF lining fluorine centrifugal pump, FSB fluorine alloy centrifugal pump.
5) Alkali (Sodium Hydroxide): The general corrosivity is not very strong, but the common alkali solution will produce crystallization. Therefore, the IHF lined fluorine centrifugal pump and FSB fluorine alloy centrifugal pump with mechanical seal with the material of Graphite 169 can be used.
6) Ammonia (ammonia hydroxide): Most metals and non-metals in liquid ammonia and ammonia (ammonia hydroxide) corrosion are minor, only copper and copper alloy should not be used. Most of the company's products for ammonia and ammonia transport. Such as fluorine plastic magnetic pump, fluorine plastic centrifugal pump can be long-term and stable use.
7) Saline (sea water): Common steel corrosion rate in sodium chloride solution and seawater, salt water is not too high, the general need to use paint protection; various types of stainless steel also have a low uniform corrosion rate, but may be due to chloride ions caused by local Sexual corrosion, usually 316 stainless steel is better. Various types of chemical pump companies are applicable.
8) alcohols, ketones, esters, ethers: common alcohol medium with methanol, ethanol, ethylene glycol, propanol, ketone medium with acetone, butanone and so on, ester medium has a variety of methyl ester , Ethers, ethers medium ether, ether, butyl ether, etc., their basic corrosive is not strong, so you can use ordinary stainless steel, the specific choice should be based on the media properties and related requirements to make a reasonable choice. It is also noteworthy that ketones, esters, ethers are soluble in a wide variety of rubbers and avoid mistakes when selecting sealing materials.
There are many other media can not be introduced in this one, in short, should not be arbitrarily and blindly selected materials, should consult more information or learn from mature experience.
2, the sealing problem: no leakage is the pursuit of chemical equipment forever, it is this requirement has led to the growing use of magnetic pump. However, there is still a long way to go without leakage, such as the life span of the magnetic pump isolation sleeve, the material pitting problem, the reliability of the static seal, and the like. Now some of the basic aspects of sealing a brief introduction is as follows:
1) Sealing type: For static sealing, there are usually two forms of sealing gasket and sealing ring, while the sealing ring is the most widely used for O-ring. For dynamic sealing, chemical packing is seldom used for packing, The main, mechanical seal and a single and double-ended, balanced and unbalanced, balanced type for high pressure medium seal (usually refers to pressure greater than 1.0MPa), double-ended mechanical seal is mainly used for high temperature, easy crystallization, Viscous, particle-containing and toxic volatile media, double-ended mechanical seal should be injected into the sealed chamber isolation fluid, the pressure is generally higher than the media pressure 0.07 ~ 0.1MPa, single-ended mechanical seal with easy installation and maintenance, without adding cooling liquid isolation , Moderate price advantages, is widely used in chemical pump a dynamic seal form.
2 ) Sealing material: Chemical magnetic pump static sealing materials generally use fluoroelastomers, special circumstances before using PTFE material; mechanical seal ring static material configuration is more critical, not the best cemented carbide and carbide grinding on the best , The high price is on the one hand, there is no hardness difference between the two is not reasonable, it is best treated according to the characteristics of different media, the mechanical seal of our company have silicon carbide on the PTFE (basic configuration), silicon carbide on silicon carbide , Alumina ceramic on PTFE, silicon carbide on alumina ceramics, cemented carbide on cemented carbide for users to choose to configure use.
3, the viscosity of the problem: the viscosity of the medium on the performance of the pump is great, when the viscosity increases, the pump head curve down, the best conditions of the head and flow are decreased, while the power is then increased, and thus Reduced efficiency. General parameters on the sample are the performance of the transport of water, when the transport of viscous media should be converted (different viscosity correction factor can be found in the relevant conversion chart). For the viscosity of the pulp, paste and viscous liquid delivery, the proposed selection of mortar pump, my company's UHB-ZK corrosion-resistant mortar pump can be applied to the viscosity or with corrosive media particles.
Second, pump selection principles: Design Institute in the design of equipment, to determine the pump usage and performance parameters and select the pump. First of all, this choice from the choice of pump type and form of the beginning, then what principle to choose the pump? What is the basis? 1, Make the type and performance of the selected pump meet the requirements of process parameters such as device flow, head, pressure, temperature, NPSH, suction and so on;
2, must meet the requirements of the characteristics of the media, the transmission of flammable, explosive toxic or valuable medium pump requires shaft seal reliable or non-leak pump, such as magnetic drive pump (without shaft seal, using isolated magnetic indirect drive) Conveyor corrosive media pump, convection parts require corrosion-resistant materials, such as fluorine plastic corrosion-resistant pump, the pump containing solid particulate media, convection parts require wear-resistant materials, if necessary, the shaft seal with a cleaning liquid rinse ;
3, the mechanical requirements of high reliability, low noise, small vibration;
4, the correct calculation of pump purchase cost of investment. See: How to correctly calculate the cost of purchasing the pump.
Third, the basic pump selection reference:
(A), the following is the basic pump selection method:
1, conveying corrosive media (such as "concentrated sulfuric acid, concentrated nitric acid"), the transport of flammable and explosive media, the use of the environment can not have any pollution - the choice of magnetic pumps, such as "CQB series of magnetic pumps, IMD series Magnetic pump, for self-priming - optional ZMD series of magnetic pump;
2, IHF centrifugal pump and FSB centrifugal pump with high speed, small size, light weight, high efficiency, large flow, simple structure, infusion without pulsation, stable performance, easy operation and maintenance features such as the use of conditions no special requirements When, - Selection of centrifugal pump is better;
3, the delivery of solid particles containing the chemical medium pump, convection parts require wear-resistant materials - the best choice for mortar pump, UHB-ZK corrosion-resistant mortar pump material for the new high-strength engineering plastics UHBWPE, which is a Species of modified ultra-high molecular weight (5 million or more) polyethylene. In plastic, it has the most excellent wear resistance, experimental contrast, its wear resistance is much higher than stainless steel, and impact resistance, creep resistance and excellent corrosion resistance (and F4), as well as No adhesion and other unique properties;
4, when the liquid level in the pump below the installation location - FZB self-priming pump should be used, such as the need to meet the leakage characteristics - optional ZMD magnetic pump.
(B), according to the pump performance curve to select the best model specifications When the use of performance parameters can not find the appropriate type of table - can refer to the pump performance curve to choose the most suitable pump.
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