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        to provide excellent products and high quality services to customers

        Yingkou chemical acid pump how to detail the selection of acid - alkali pump

        Date:2019-02-28 Author: Click:

        I. basic basis

        1. Flow is one of the important performance data of the pump, which is directly related to the production capacity and delivery capacity of the whole device.If the design institute process design can calculate the pump normal, minimum, maximum three kinds of flow.Pump selection, based on the maximum flow, both normal flow, in the absence of maximum flow, usually take 1.1 times the normal flow as the maximum flow.

        2. The head required by the device system is another important performance data of the pump, which is generally selected by amplifying the 5%~10% allowance.

        3. The liquid properties, including the name of the liquid medium, physical properties, chemical properties and other properties, physical properties with temperature c d density, viscosity, u, solid particle diameter and gas content in the medium, etc., this is related to the system of the head, effective computing cavitation allowance and appropriate pump type: chemical properties, mainly refers to the chemical corrosion resistance and toxicity of liquid medium, is what kind of shaft seal material selection and the selection of pump type of important basis.

        4. The pipeline layout condition of the device system refers to the liquid feeding height, the liquid feeding distance, the liquid feeding direction, the lowest liquid level on the suction side, the highest liquid level on the discharge side, and some data and pipeline specifications, as well as the length, material, pipe fitting specifications and quantity, etc., for the purpose of calculating the carding head and checking the cavitation allowance.

        5. There are many operating conditions, such as liquid operation T saturated steam force P, suction side pressure PS (absolute), discharge side container pressure PZ, altitude, environmental temperature operation is clearance or continuous, pump position is fixed or movable.(welcome to WeChat: pump circle)

        The influence of corrosion

        Corrosion has long been one of the most troublesome hazards of chemical equipment.According to relevant statistics, about 60% of the destruction of chemical equipment is caused by corrosion, so in the chemical pump selection should first pay attention to the scientific selection of materials.There is a kind of misunderstanding normally, think stainless steel is "all-purpose material", no matter what medium and environmental condition hold out stainless steel, this is very dangerous.The following for some common chemical media to talk about the main points of material selection:

        1. As one of the strongly corrosive media, sulfuric acid is an important industrial raw material with a wide range of USES.Corrosion of different concentration and temperature of sulfuric acid on the material difference is bigger, the concentration is above 80%, the temperature is less than 80 ℃ concentrated sulfuric acid, carbon steel and cast iron has good corrosion resistance, but it is not suitable for high-speed flow of sulfuric acid, is not used as a pump valve materials;Common stainless steel such as 304(0Cr18Ni9), 316(0Cr18Ni12Mo2Ti) for 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).Fluoroplastic has better sulfuric acid resistance, using fluorine pump (F46) is a more economical choice.The company's applicable products are: IHF fluorine pump, PF(FS) strong corrosion resistant centrifugal pump, cqb-f fluorine plastic magnetic pump, etc.

        2. The vast majority don't hydrochloric acid corrosion resistant metal materials hydrochloride (including all kinds of stainless steel materials), also can only be used for high silicon molybdenum 50 ℃ and below 30% hydrochloric acid.In contrast to metallic materials, most non-metallic materials have good corrosion resistance to hydrochloric acid, so lining rubber pump and plastic pump (such as polypropylene, fluoroplastic, etc.) is the best choice for transporting hydrochloric acid.The company's applicable products are: IHF fluorine pump, PF(FS) strong corrosion resistant centrifugal pump, CQ polypropylene magnetic pump (or fluoroplastic magnetic pump), etc.

        3. The most general metal nitrate was rapidly in nitric acid corrosion damage, stainless steel is the most widely used of nitric acid resistant material, all on room temperature the concentration of nitric acid have good corrosion resistance, it is important to note that the molybdenum stainless steel (e.g., 316, 316 l) of nitric acid corrosion resistance not only no better than ordinary stainless steel (e.g., 304, 321), sometimes even less.For high temperature nitric acid, usually titanium and titanium alloy materials.The company's applicable products are: DFL(W)H chemical pump, DFL(W)PH shielding chemical pump, DFCZ flow pump, DFLZP self-priming chemical pump, IH chemical pump, CQB magnetic pump, etc., the material is 304.

        4 acetic acid it is one of the most corrosive substances in organic acid, ordinary steel in all concentration and temperature of acetic acid will seriously corrosion, stainless steel is an excellent anti-acetic acid material, molybdenum-containing 316 stainless steel is also suitable for high temperature and dilute acetic acid steam.For high temperature high concentration acetic acid or contain other corrosive medium such as demanding, can choose high alloy stainless steel or fluoroplastic pump.

        5. Alkali (sodium hydroxide) steel is widely used in under 80 ℃, 30% concentration of sodium hydroxide solution, there are also many factory under 100 ℃, 75% still USES the ordinary steel, while the corrosion increases, but the economy better.The corrosion resistance of ordinary stainless steel to lye has no obvious advantages over cast iron, and stainless steel is not recommended as long as a small amount of iron is allowed in the medium.For the high temperature lye mostly titanium and titanium alloy or high alloy stainless steel.The company's general cast iron pump can be used for room temperature low concentration lye, special requirements can be used for all kinds of stainless steel pump or fluoroplastic pump.

        6. Ammonia (ammonia hydroxide) the corrosion of most metals and non-metals in liquid ammonia and ammonia water (ammonia hydroxide) is very minor, and only copper and copper alloys are not suitable for use.Most of the company's products are suitable for the transmission of ammonia and ammonia water.

        7. The corrosion rate of ordinary steel in salt water (sea water) is not too high in sodium chloride solution, sea water and salt water, so coating protection is generally required;All kinds of stainless steel also have very low uniform corrosion rate, but may cause local corrosion due to chloride ions, usually 316 stainless steel is better.All kinds of chemical pump companies have 316 material configuration.

        8. Alcohols, esters, ketones, ethers, common alcohol medium such as methanol, ethanol, ethylene glycol, propylene glycol, ketone medium such as acetone, butanone, there are all kinds of methyl esters medium, ethyl ester, ethers media such as methyl ether, ethyl ether, butyl ether, their basic no corrosive, commonly used materials are applicable, the specific selection should also according to the requirements of the dielectric properties and related make reasonable choice.It is also worth noting that ketone, ester, ether on a variety of rubber solubility, to avoid errors in the selection of sealing materials.

        Iii. Influence of other factors

        General industrial pumps in the process flow can ignore the amount of leakage in the pipeline system, but must consider the impact of process changes on the flow.Agricultural pump if it is to use open channel water, must also consider leakage and evaporation.

        Pressure: suction tank pressure, drain tank pressure, differential pressure in piping system (head loss).

        Piping system data (pipe diameter, length, type and number of pipe fittings, geometric elevation of suction tank to pressure tank, etc.).

        Device characteristic curves should be drawn if necessary.

        Iv. Influence of pipelines

        When designing and arranging pipelines, attention should be paid to the following matters:

        A. Reasonable selection of pipe diameter, large pipe diameter, under the same flow rate, small liquid flow speed, small resistance loss, but high price, small pipe diameter, will lead to A sharp increase in resistance loss, so that the selected pump head increase, with increased power, costs and operating costs increase.Therefore, it should be considered from the perspective of technology and economy.

        B. The discharge pipe and its joints shall take into account the maximum pressure they can bear.

        C. piping layout should decorate straight pipe as far as possible, try to reduce the attachment and try to narrow the pipe length, pipe must turn, elbow bend radius should be 3 ~ 5 times the diameter of the pipe, Angle is greater than 90 ℃ as much as possible.

        D. The discharge side of the pump must be equipped with valves (ball valves or globe valves, etc.) and check valves.The valve is used to adjust the working point of the pump, and the check valve can prevent the pump from reversing when the liquid flows back, and make the pump avoid the impact of water hammer.(when the liquid flows back, it will generate huge reverse pressure and damage the pump.)

        Influence of flow head

        Determination of flow

        A. If the minimum, normal and maximum flow rate has been given in the production process, the maximum flow rate shall be considered.

        B. If only the normal flow rate is given in the production process, a certain amount of allowance should be considered.

        For ns100 large flow low lift pump, the flow margin shall be 5%; for ns50 small flow high lift pump, the flow margin shall be 10%; for 50 ns100 pump, the flow margin shall be 5%; for low quality and poor operating conditions, the flow margin shall be 10%.

        C. If the basic data only give weight flow, it should be converted into volume flow.

        The influence of temperature

        The transmission of high temperature medium puts forward higher requirements for the structure, materials and auxiliary system of the pump. The following is about the cooling requirements of different temperature changes and the pump type suitable for the company:

        1. For medium temperature below 120 ℃, and usually do not set up a special cooling system, much to the lubrication and cooling medium itself.As DFL (W) H chemical pump, DFL (W) PH shielding chemical pump (over 90 ℃ when the shielding motor protection grade class H) should be adopted;While DFCZ regular and IH chemical pump with suspension structure can make the maximum temperature of 140 ℃ ~ 160 ℃;IHF fluorine-butterfly pump use highest temperature can reach 200 ℃;Only CQB magnetic pump common use temperature does not exceed 100 ℃.It is worth mentioning that for the easy to crystallize or contain particles of the medium should be equipped with sealing surface flushing pipeline (design are left with the interface).

        2. For more than 120 ℃, 300 ℃ medium, generally on the pump cover shall be equipped with cooling cavity, seal chamber should also turn on the cooling liquid (with a double mechanical seal is required), when do not allow the cooling fluid infiltration media, should be taken to itself after cooling medium access can be realized through the simple heat exchanger ().At present, the company has a DFCZ type chemical process pumps, GRG high temperature pipelines and HPK hot water circulating pump (under development), with another CQB - G type high temperature magnetic pump can be used in the high temperature of 280 ℃ medium.

        3. For the high temperature of 300 ℃ above medium, not only need cooling pump head part, suspension bearing room should be equipped with cooling system, the pump structure generally support form for the center, had better use the metal bellows mechanical seal type, but the price is high, the price is more than 10 times PuTongJi sealing).At present, the company only DFAY centrifugal oil pump use temperature can reach 420 ℃ (under development).

        Vii. Influence of tightness

        No leakage is always the pursuit of chemical equipment, it is this requirement contributed to the growing application of magnetic pump and shielded pump.However, there is still a long way to go to achieve no leakage, such as magnetic pump isolation sleeve and shield pump shield sleeve life problems, material hole erosion problems, static seal reliability problems and so on.Now some basic information about sealing is briefly introduced.

        1. For static seals, there are usually only two forms of gasket and sealing ring, and the sealing ring is the most widely used o-ring;For dynamic seal, chemical pump packing seal, is scarcely used to is given priority to with mechanical seal, mechanical seal and single face and double face, equilibrium and non-equilibrium model, equilibrium model is suitable for the seal of high pressure medium (usually refers to the pressure is greater than 1.0 MPa), double end face sealing machine is used for high temperature, easy to crystallization, viscosity, and toxic volatile medium including particle, double end face machine sealing should be added spacer to the sealed cavity, the pressure is generally higher than that of medium pressure is 0.07 ~ 0.1 MPa.

        2 sealing materials chemical pump static sealing materials generally use fluorine rubber, special cases only use teflon materials;Mechanical seal static and dynamic ring material configuration is more critical, is not hard alloy to hard alloy is the best, the price is high on the one hand, there is no hardness difference between the two is not reasonable, so it is best to treat differently according to the characteristics of the medium.

        (note: API 610 version 8 of the API 610 specification for mechanical seals and piping systems is detailed in appendix D.)

        Viii. Influence of viscosity

        The viscosity of the medium has a great impact on the performance of the pump, when the viscosity increases, the pump head curve decreases, the best working condition of the head and flow are decreased, and the power is increased, so the efficiency is reduced.In general, the parameters on the sample are the performance in the delivery of clear water, and the conversion should be carried out when the viscous medium is delivered (the correction coefficient of different viscosity can be referred to the relevant conversion chart).For the high viscosity of slurry, paste and viscous liquid transport, it is recommended to choose screw pump, the company DFGG single screw pump applicable medium viscosity up to 1000000cst.

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