NIKUNI diaphragm pump was granted an invention patent by China National Intellectual Property Administration for its novel and unique " piston chamber hydraulic pressure linkage & propulsion mechanism".
The HP Series multi piston diaphragm pump using the present invention features compact structure, smooth operation, low friction and high efficiency. At the same time, the auxiliary pressure balancing device used in conjunction with above mechanism helps maintain stabilized diaphragm operation and extended service life and at the same time ensure zero leakage of the conveyed medium.
The HP Series multi piston diaphragm pump using this technology is suitable for transportation of various pure liquids, solvents, chemical liquids, corrosive liquids, liquefied gases, slurries and high viscosity materials; It is applicable to high-pressure filtration and separation equipment, high-pressure cleaning equipment, high-pressure cooling equipment, seawater desalination and reverse osmosis equipment, oil and gas field pressure water injection equipment, spray drying equipment, coolant feeding equipment for deep hole metal cutting equipment, high-pressure tubular boiler, multi-channel reactor and other high-pressure liquid feeding equipment that requires metering capability.
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In August 2024, NIKUNI large flow multiphase flow mixing pump was granted a product invention patent by the China National Intellectual Property Administration.
This product is a structurally innovative product conceived by our company based on years of accumulated experience in product design and applications. The maximum flow rate of this pump can reach 120 cubic meters per hour and the effective gas suction and mixing can reach 17% without reducing the flow rate.
This product is suitable for fine mixing of liquid with liquid, gas with liquid and can be used in mixing & reaction processes in the fine chemical industry (simplifying or replacing reaction tanks), pressurized dissolved air flotation, biochemical aeration, river or lake water oxygenation and purification, food grade drinking water ozone sterilization, fruit and vegetable ozone sterilization and preservation, agricultural and fishery water sterilization and oxygenation for higher output and many other applications in the water treatment industry.
Please feel free to contact us in case of needs.
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New product to the NIKUNI lineup of industrial pumps
The LP Series regenerative turbine pump is an economical coaxial pump product newly developed, consisting of cast iron LPFD Series and stainless steel LPSD Series. These pumps are suitable for various small industrial equipment such as mold temperature regulation machines, chillers, cleaning equipment, steam generators, ozone water generation equipment, small sewage treatment equipment, etc.
這二個(gè)系列產(chǎn)品將于2024年9月批量上市，歡迎設(shè)備廠家采購試用。
]]>The common liquid ring compressor is the same as the liquid ring vacuum pump, with its impeller eccentrically installed inside the housing. Under the centrifugal force of the high-speed rotating impeller, the sealing liquid inside the shell forms a closed liquid ring along the inner wall. The flat port plate installed inside the liquid ring compressor housing is equipped with a semi-circular suction port and compression port for gas. These two ports are divided by the blades of the impeller into a gas suction space from small to large and a gas compression space from large to small. With the high-speed rotation of the impeller and the continuous suction and compression of gas, the gas that needs to be processed is sent to the outlet pipeline of the compressor.
2、 Characteristics of liquid ring compressor
Unlike other types of compressors, the liquid ring compressor uses the sealing liquid in the casing as the working medium, making it a variable volume compressor. The blades of the impeller transmit centrifugal force to the sealing liquid, generating suction and compression forces similar to those of a piston. Its main features are as follows:
1. Gas and liquid can be mixed and transported. The liquid carried in the inhaled gas will not have any adverse effects on the normal operation of the compressor;
2. The configuration of gas inlet and outlet pipelines is simple and easy to operate and manage;
3. With appropriate control of the sealing liquid temperature, the temperature rise of the processed gas during suction and compression discharge is small and the exhaust temperature is low, without the need for a complex gas cooling system;
4. The structure of the liquid ring compressor is simple, with only one rotating component, no metal contact, few failures and easy maintenance;
5. Due to the high-speed rotation and continuous suction of compressed gas by this compressor, there will be no significant fluctuations in its outlet pressure and flow rate;
6. Liquid ring compressors are particularly suitable for handling gases that are easily decomposed at high temperatures, flammable and explosive gases, gases that do not contain solid particles and are insoluble or slightly soluble in sealing liquids and corrosive gases.
3、 Single action liquid ring compressor and double action liquid ring compressor
There are two types of liquid ring compressors: single action liquid ring compressors and double action liquid ring compressors. Although both types of liquid ring compressors are used for gas compression and transportation, there are some differences in construction, function, and application.
1. Single action liquid ring compressor
The structural feature of a single action liquid ring compressor (or flat port plate compressor) is that the impeller is eccentrically installed inside the compressor housing and a flat port plate is equipped with a gas suction port and a gas compression & discharge port. The impeller only produces one gas suction and compression process per rotation.
2. Double action liquid ring compressor
With the development of product design and manufacturing technology, there have been innovations in the structural design of liquid ring compressors. The new type of liquid ring compressor replaces the original flat port plate with a conical or cylindrical structure and sets up two sets of suction and exhaust ports on the distributor. The impeller of the compressor is designed to rotate around the gas distributor; In order to comply with the structural design concept of dual suction and dual exhaust of the gas distributor and fully utilize the impeller, the housing of the dual action liquid ring compressor is also optimized as a dual eccentric structure.
Due to these innovative structural changes, the impeller of the new compressor can achieve two gas suction and compression functions per revolution. This new type of liquid ring compressor is called a double action liquid ring compressor.
3. Comparison between double action liquid ring compressor and single action liquid ring compressor
Compared with single action liquid ring compressors, double action liquid ring compressors have the characteristics of a larger gas distributor opening and an expanded intake area, so they have stronger gas suction capabilities.
The increase in liquid content in the inhaled gas will have an impact on the working efficiency of the liquid ring compressor. Under the same working conditions, the efficiency decrease of the double action liquid ring compressor is smaller than that of the single action liquid ring compressor. In the presence of a condensable body, the double action liquid ring compressor is insensitive to the presence of water vapor in the intake and its pumping capacity can be greatly improved by condensing first and then compressing.
Due to the difference in intake structure, the double action liquid ring compressor has a greater advantage in operating energy consumption under the same working conditions. The energy-saving effect is particularly obvious during periods of high intake moisture content. Under the same suction volume, the power consumption of the double action liquid ring compressor is lower than that of the single action liquid ring compressor.
The suction port of a single action liquid ring compressor is generally located at the top of the compressor, and its impeller is eccentrically installed above the axis centerline; Due to the high sealing liquid level at rest, the starting current is relatively high. The position of the suction and discharge ports of the double action liquid ring compressor and the liquid level of the sealing liquid are relatively low, resulting in a smaller starting current.
A single action liquid ring compressor needs to be designed as a two-stage structure when obtaining high gas discharge pressure. In this case, its structure becomes more complex, with an increase in the number of connected first stage and second stage impellers and low-pressure and high-pressure shell components divided into two by partitions in the middle. At the same time, there are more sealing points that need to be prevented from leakage, resulting in an increase in failure points. Compared to this, the two-stage structure of the double action liquid ring compressor designed to obtain higher delivery pressure is extremely simple. Its first and second stage impellers are connected in series by two impellers of different diameters and share a distributor corresponding to the second stage gas compression. This type of double action two-stage liquid ring compressor has fewer components, fewer sealing surfaces and fewer failure points.
The rotor of the double action liquid ring compressor adopts a radial force balance design, which ensures that the force balance is not easily damaged during high-speed rotation. During the selection process of the rotor for a single action liquid ring compressor, it is greatly affected by radial forces, and long-term use carries the risk of rapid rotor damage and shaft breakage.
In summary, compared with single action liquid ring compressors, double action liquid ring compressors have adopted many innovative changes in structural design, with many advantages such as large pumping capacity, energy saving, safety and reliability, and long service life. Therefore, it has more advantages under the conditions of compressing process gases that are corrosive or carry liquids.
4. The applications of liquid ring compressor
Widely applicable in:
Compression of flammable and explosive gases such as acetylene and hydrogen and compression of toxic and corrosive gases such as chlorine
VCM recovery in PVC plant and top vacuum system in crude oil vacuum distillation
Tail gas/flare gas recovery, circulating gas compression, pressure swing adsorption (PSA), vacuum conveying of various materials, polyester production, liquid chlorine production
- 5. Product Promotion
NIKUNI double action liquid ring compressor is a cylindrical gas distributor structure compressor, which has the characteristics of easy machining accuracy guarantee, easier assembly accuracy and clearance control, and more convenient maintenance service compared to the vertebral body liquid ring compressor. At the same time, the two stage version of NIKUNI double action liquid ring compressors also adopts a patented design of impeller dynamic self balancing, which has unique advantages in protecting the compressor rotor, bearings and mechanical seals.
The current maximum working range of the NIKUNI double action liquid ring compressor is: the highest suction capacity can reach 2500 cubic meters per hour and the highest discharge pressure can reach 5.5 kilograms in a single stage and 14 kilograms in a double stage.
]]>1. Problems with using centrifugal pumps
When centrifugal pumps are being used in small flow and high head applications, as they are originally designed for large flow applications, it is often necessary to divert some or even most of the liquid through branch pipelines to meet the needs of small flow. This approach not only has problems such as bulky pump volume, high motor power consumption, thick pipeline, complex reflux structure, and difficult control, but also has problems such as high initial equipment investment and high long-term operation and maintenance costs.
When multi-stage centrifugal pumps are used to achieve high head, it is inevitable that there will be problems such as complex structure of multi-stage pumps, large operating inertia that is not suitable for sudden starts and stops and frequent misfunctions.
2. Problems with using reciprocating pumps
Although reciprocating pumps have the characteristic of easily achieving high head, their reciprocating motion inevitably causes high pulsation, which cannot be completely eliminated even with a stabilizer (or accumulator). At the same time, when transporting high-temperature and impurity containing liquids, reciprocating pumps (plunger pumps) often have problems such as frequent failures and high maintenance costs. Therefore, reciprocating pumps are generally not suitable for operating conditions that require high stability in liquid delivery.
3. Problems with using gear pumps
Due to the contact friction between gears, gear pumps often experience performance degradation caused by gear wear during use, and are not suitable for transporting high-temperature liquids due to limitations in metal expansion coefficients.
4. Problems with using high-speed pumps
The speed range of the high-speed pump is between 3500-25000 rpm, driven by an integral gearbox. The structure of the integral gearbox is complex and in order to control vibration and noise levels, high machining accuracy and overall fitting accuracy of the constituent parts are required. At the same time, a forced lubrication system is also needed to ensure its normal operation. High speed pumps not only have high production costs and expensive prices, but also require complex maintenance and correspondingly high repair costs.
一. 1. Regenerative turbine pumps are suitable for small flow and high head applications in chemical processes
In working conditions of small flow and high head liquid transfer, NIKUNI regenerative turbine pump has advantages that cannot be replaced by the above-mentioned pumps. The main features of the NIKUNI regenerative turbine pump are as follows:
1. Compact size and simple structure
NIKUNI regenerative turbine pump features fewer wet components, small size, simple structure and easy maintenance and repair.
2. Suitable for complex and demanding usage conditions
NIKUNI has a full lineup of regenerative turbine pumps which are designed and manufactured according to special operating conditions, with good resistance to gas corrosion, high temperature, and suitable for gas-liquid mixture transportation. They are especially suitable for harsh operating conditions such as small flow, high head, etc. that other pumps find hard to cope with in chemical processes.
3. Reasonable design, high quality and long-term stable performance
After more than 70 years of continuous improvement and optimization, the unique design and excellent performance of the NIKUNI regenerative turbine pump are at the forefront of the world. Strict material control and precision machining with CNC equipment provide reliable guarantees for product accuracy and quality.
The biggest difference between NIKUNI regenerative turbine pumps and similar products by other pump manufacturers lies in the fixing method of its impeller. NIKUNI ensures the concentricity and parallelism of the pump shaft and impeller through precision machining and fixes the impeller of the pump at the shaft end, strictly controlling the clearances between the impeller and the pump body. Apart from the mechanical seal of the rotating components, there is no direct contact or friction between the parts of the pump during operation, ensuring the long-term stability of the pump's performance.
4. Rich product lineup and wide corresponding scope
NIKUNI has developed numerous series of products to meet the needs of industrial development, including high temperature, low temperature, low melting point, low flash point, easy boiling, flammable and explosive, highly toxic, radioactive, ultra clean and valuable fluids. The high self-priming variety (~8 meters), ultra-low NPSH (0.3 meters), heat medium variety (~350 ℃ without cooling), gas-liquid or liquid-liquid mixed transportation variety, and leak free variety of loaded magnetic drives in its chemical process pump varieties have been widely used in the domestic petrochemical and fine chemical industries.
A single-stage impeller of the NIKUNI regenerative turbine pump can achieve a pressure of~17 kilograms, while double stage impellers can achieve a pressure of~30 kilograms; The inlet port diameter of the pump varies from 15 to 100 millimeters, making it easy for users to choose within the flow range of 0.1 to 50 cubic meters.
According to actual needs, NIKUNI can also customize products that comply with API610 specifications for users.
二. Application of NIKUNI regenerative turbine Pump in Chemical Processes
1. In the production process of chemical product sulfoxide, it is necessary to transport media that are easily gasified and contain impurities. Centrifugal pumps have low gasification resistance and are difficult to meet the production process requirements. Due to the replacement of the original centrifugal pump with a NIKUNI regenerative turbine pump by the user, the frequent malfunctions and pump damage that caused serious economic losses during the production process have been completely resolved. At present, NIKUNI regenerative turbine pump has become one of the key equipment in the production process of sulfoxides.
2. The conventional production process of ammonia methanol requires a complex mixed reaction process and requires the use of various large equipment (pumps, valves, reaction vessels, etc.) to achieve product integration production process. The conventional production process faces difficulties such as expensive production equipment, difficult operation and maintenance, environmental pollution caused by gas leaks and long-term high production costs.
After users replaced the original mixed reaction process and related equipment with NIKUNI regenerative turbine pumps, they not only easily achieved the goal of simplifying the process, but also reduced equipment investment and production costs, while fundamentally solving the problem of environmental pollution.
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硝酸( HNO 3 )
一般特點(diǎn)：屬氧化性介質(zhì)。濃HNO 3工作溫度一般為40℃以下，元素 Cr 、Si為抗氧化性，含Cr 、
Si 的不銹鋼和其它材料為濃 HNO 3 的耐蝕理想材料。
高硅鑄鐵(STSi15R)：溫度 93% 以下的一切溫度；
高鉻鑄鐵(Cr28)：溫度 80% 以下的一切溫度；
不銹鋼(SUS304 、 SUS316 、 SUS316L)：溫度 80% 以下的一切溫度；
S-05鋼(0Cr13Ni7Si4)：溫度 98% 以下的一切溫度；
工業(yè)純鈦(TA1 、TA2)：沸點(diǎn)以下的一切溫度（除發(fā)煙外）；
工業(yè)純鋁(Al)：室溫的一切溫度（僅用于容器）；
CD-4MCu 時(shí)效硬化合金：沸點(diǎn)以下的一切溫度；
因可耐、哈氏合金 C 、金、鉭等都有良好的耐蝕性。
一般特點(diǎn)：沸點(diǎn)隨濃度升高而升高。如：濃度 5% ，其沸點(diǎn)為 101 ℃；濃度 50% ，其沸點(diǎn)為124℃； ?濃度 98% ，其沸點(diǎn)為 332℃。濃度 75%以下呈還原性（或呈中性），超過 75% 呈氧化性。不銹鋼 (SUS316 、 SUS316L) ：溫度 40 ℃以下，濃度 20% 左右；
904 鋼 (SUS904 、 SUS904L) ：適于溫度 40~60 ℃、濃度 20~75% ；溫度 80 ℃、濃度 60% 以下；高硅鑄鐵 (STSi15R) ：室溫至 90 ℃之間各種濃度；純鉛、硬鉛：室溫的各種溫度；
S-05 鋼 (0Cr13Ni7Si4) ： 90 ℃以下的濃硫酸，高溫濃硫酸（ 120~150 ℃）；
普通碳鋼：室溫 70% 以上的濃硫酸；
鑄鐵：溫度為室溫的濃硫酸；
蒙乃爾、金屬鎳、因可耐爾：中溫中等濃度的硫酸；
鈦鉬合金 (Ti-32Mo) ：沸點(diǎn)以下、 60% 的硫酸和 50 ℃以下、 98% 的硫酸；
哈氏合金 B 、 D ： 100 ℃以下、 75% 的硫酸；1 K5 A4 K1 `6 D
哈氏合金 C ： 100 ℃左右的各種溫度；
鎳鑄鐵 (STNiCr202) ：室溫 60~90% 的硫酸。
鹽酸 (HCl)
一般特點(diǎn)：還原性介質(zhì)，最高溫度為36~37%.沸點(diǎn)：濃度在 20% 時(shí)，為110 ℃；濃度在20~36%時(shí)，為 50℃；因此鹽酸的最高溫度為 50 ℃。
金屬鉭 (Ta) ：對鹽酸是最理想的耐蝕材料，但價(jià)昂貴，常用于要求精度的計(jì)量裝置；
哈氏合金 B ：溫度≤ 50 ℃、濃度 36% 的鹽酸；
鈦鉬合金 (Ti-32Mo) ：全溫度和全濃度；
鎳鉬合金 (Ch1orimetz 、 0Ni62Mo32Fe3) ：全溫度和全濃度；
工業(yè)純鈦 (TA1 、 TA2) ：室溫 10% 以下的鹽酸；
ZXSNM(L) 合金 (00Ni70Mo28Fe2) ：溫度 50 ℃、濃度 36% 的鹽酸；
磷酸(H3 PO4)
磷酸濃度一般為30~40% ，溫度為 80~90 ℃，磷酸中常含 H 2 SO 4 、 F 離子、Cl 離子、硅酸鹽等。
不銹鋼 (SUS316 、 SUS316L) ：濃度 85% 以下的沸點(diǎn)磷酸；
Durimet20(20 號(hào)合金 )：濃度 85% 以下、沸點(diǎn)以下的溫度，耐蝕耐磨合金；
CD-4Mcu：時(shí)效硬化合金，耐蝕耐磨合金；
高硅鑄鐵(STSi15R)、高鉻鑄鐵 (Cr28)：適于沸點(diǎn)以下各種濃度的硝酸；
904 、 904L ：沸點(diǎn)以下各種濃度硝酸；
沸點(diǎn)以下的各種濃度硝酸。
氫氟酸 (HF)
一般特點(diǎn)：氫氟酸毒性很大。高硅鑄鐵、陶瓷和玻璃一般對多數(shù)酸都耐蝕，但氫氟酸對它卻腐蝕。
鎂(Mg) ：對氫氟酸是理想的耐蝕材料，一般只做容器；
鈦：適用于濃度為 60~100% （室溫狀態(tài)），濃度低于 60% 腐蝕速度增加；
蒙乃爾合金：是耐氫氟酸的突出材料，能耐一切溫度和一切濃度（包括沸點(diǎn)）；
銀(Ag) ：沸騰的氫氟酸，多用于計(jì)量裝置。
燒堿 (NaOH)
一般特點(diǎn)：燒堿的腐蝕隨溫度升高而加劇。
SUS304 、 SUS304L 、 SUS316 、 SUS316L ：濃度 42% 、室溫至 100 ℃；
鎳鑄鐵 (STNiCr202) ：濃度 40% 以下，溫度 100 ℃以下；
Incolloy804 、 825 ：濃度 (NaOH+NaCl)42% 可達(dá) 150 ℃；
純鎳：濃度 (NaOH+NaCl)42% 可達(dá) 150 ℃；
蒙乃爾合金：高溫、高濃度的燒堿。
純堿 (Na2 CO3)
純堿母液含 20~26%NaCl 、 78%Cl 2 、 2~5%CO 2 ，溫度變化范圍為 32~70 ℃。
高硅鑄鐵：適于溫度為 32~70 ℃、濃度 20~26% 的純堿；
工業(yè)純鈦：目前國內(nèi)數(shù)家大型純堿廠母液等介質(zhì)均采用了用鈦制造的鈦泵。
石油化工、醫(yī)藥、食品等
石 油：0Cr13 、1Cr13 、1Cr17；
石油化工：1Cr18Ni9(304) 、
甲 酸： 904 、 904L ；
醋 酸：鈦（ Ti ）、 316L ；
醫(yī) 藥：高硅鑄鐵、 SUS316 、 SUS316L ；
食 品： 1Cr18Ni9 、 0Cr13 、 1CR13 ；
]]>As cavitation and gas entrapment may cause serious damage to centrifugal pumps, it is necessary to have a detailed understanding of the causes cavitation and gas entrapment and adopt preventive measures to prevent them during operation and ensure the normal and efficient operation of centrifugal pumps.
Causes of air entrapment
Air entrapment will occur if the centrifugal pump is not filled with liquid before starting or if air is trapped the pump during operation. As the density of air is lower than that of liquid it is difficult to throw air out with centrifugal force. The fluid inside the pump generates negative pressure due to the centrifugal motion of the motor, which is not enough to suck the liquid into the pump. As a result, the pump loses its self-priming ability and cannot transport liquid as if it is bound by "air", which is called the air entrapment of centrifugal pump.
Generating hazardous situations
The pump cannot deliver liquid, causing severe vibration in the equipment and accompanied by strong piercing noise. The motor runs idle, which can easily burn out the motor. Affects the efficiency of liquid transportation and the normal operation of centrifugal pumps.
preventive measures
Before starting, the pump should be filled with the liquid and the outlet valve should be closed when starting. To prevent the liquid fed into the pump from flowing into the low-level tank due to gravity, a check valve (foot valve) should be installed at the inlet of the pump suction pipeline; If the position of the pump is lower than the liquid level in the tank, there is no need to pump during startup. Ensure proper sealing of the casing, and ensure that the inlet valve does not leak and has good sealing performance.
Reasons of cavitation
When the liquid sucked into the pump vaporizes at the suction port due to a decrease in pressure, it causes a huge hydraulic impact on the inner wall of the pump casing, making it appear to be corroded by "air". This phenomenon is called cavitation.
The main causes of cavitation are:
1. The resistance of the inlet pipeline is too high or the pipeline diameter is too small;
2. The temperature of the conveying medium is too high;
3. Excessive flow, which means the outlet valve is almost fully open;
4. The installation location is too high above liquid surface, which affects the suction capacity of the pump;
5. Improper selection, including pump selection and pump material selection, etc.
The liquid containing bubbles rapidly condenses or ruptures after being squeezed into the high-pressure zone. Due to the disappearance of bubbles, a vacuum is generated and the surrounding liquid flows towards the center of the bubble at extremely high speeds, instantly generating a high-speed impact force of up to tens of thousands of kPa, causing impact on the pump impeller and pump casing, resulting in material erosion and damage.
About the different causes of cavitation and air entrapment, air entrapment refers to the air trapped in the pump, which usually occurs when the pump is started, mainly manifested by the incomplete discharge of air out of the pump; And cavitation is caused by the liquid reaching its vaporization pressure at a certain temperature.
Location of cavitation occurrence
According to the different locations where cavitation occurs in water pumps, cavitation can be divided into the following four categories:
Impeller surface cavitation:
The reasons of Impeller surface cavitation are either caused by installation position of the pump too high above liquid level or the pump flow rate deviates too much from the designed flow rate. The formation and collapse of air bubbles often occur on the front and back of the impeller or on the inner surface or rear end of the impeller.
Clearance cavitation:
When water flows through the suddenly narrowing clearances between the impeller and pump body, flow speed increases while the local pressure decreases and cavitation also occurs. In the clearances between the outer edge of the axial flow pump impeller and the pump casing, as well as the clearances between the sealing ring of the centrifugal pump and the outer edge of the impeller, the large pressure covers on the inlet and outlet sides of the impeller cause rapid backflow, resulting in local pressure drop and cavitation in the clearances.
Vortex strip cavitation:
Because of poor design of the water collection tank and inlet channel or as the result of the pump working in quite different condition than originally designed, a vortex strip may also be generated below the impeller from top to bottom. When the center pressure of the vortex strip is lower than the vaporization pressure, it becomes a cavitation strip.
Rough cavitation:
Rough cavitation refers to the phenomenon where water flows through the uneven inner walls and wet components of a pump and local negative pressure is easily generated downstream of the protrusions, leading to cavitation. This type of cavitation is called rough cavitation.
Harm situation generated
(1) Pump performance get deteriorated and when cavitation occurs large quantity of air bubbles will be generated. When water contains a large quantity of air bubbles, it disrupts the normal flow pattern, reduces the effective flow surface area of the impeller passage, changes the flow direction and increases energy loss, causing a rapid decrease in the flow rate, head and efficiency of the pump. In severe cases of cavitation, even flow interruption may occur.
(2) Damaged wet components cause local deformation and hardening of the metal surface on the pump interior surface under repeated high-intensity impact forces, resulting in metal fatigue and causing metal fracture and peeling. In addition to mechanical effects, there are also chemical corrosion of metals by deeply active gases (such as oxygen) escaping from water, as well as electrochemical corrosion of metals by water. Under the comprehensive action, the interior surface of the pump initially appears as pockmarks, which then turn into honey comb like structures and in severe cases, the pump body may be eroded and broken in a short period of time.
Vibration and noise will generate. When bubbles collapse, liquid particles collide with each other and also with the metal surface, producing various frequencies of noise. In severe cases, a "cracking" explosion sound can be heard inside the pump, causing vibration of the unit.
So, noise and vibration are also one of the main criteria used to determine whether cavitation occurs and disappears.
preventive measures
An effective measure to reduce cavitation is to prevent the generation of bubbles.
Firstly, the surface moving in the liquid should be streamlined to avoid the occurrence of vortex in local areas, as the pressure in the vortex zone is low and bubbles are easily generated. In addition, the gas content in the liquid and the disturbance in the liquid flow should be reduced, which will also limit the formation of bubbles.
Choosing appropriate materials can improve the ability to resist cavitation. Metal materials with high strength and toughness usually have good resistance to cavitation and improving the material's corrosion resistance will also reduce cavitation damage.
The inlet pressure of a centrifugal pump should not be too low but should have a minimum allowable value. The corresponding cavitation allowance is called the necessary cavitation allowance, which is generally measured by the pump manufacturer through cavitation experiments and listed as the performance of the centrifugal pump in the pump product sample. When the pump is operating normally, the actual NPSHa must be greater than the NPSHr, which is specified in Chinese standards to be greater than 0.5m or more.
At the same time, foreign objects in the inlet pipeline should be cleaned to ensure smooth flow or the diameter of the pipe should be increased.
In addition, for pump manufacturers, it is necessary to improve the ability of centrifugal pumps to resist cavitation, such as improving the structural design from the suction port to the impeller; Adopting a front inducer to increase liquid flow pressure; Increase the impeller inlet angle and reduce the bending at the blade inlet to increase the inlet area of the pump to prevent the occurrence of cavitation.
Air entrapment and cavitation in centrifugal pumps has a very adverse effect on them. Before using centrifugal pumps it is necessary to follow the operating procedures to avoid the occurrence of air entrapment. At the same time, it is necessary to regularly inspect and maintain the inlet and outlet pipelines as well as the impeller of the centrifugal pump to prevent the occurrence of cavitation.
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In the liquid-phase application of ozone, the more traditional and widely used process is ozone generator + booster pump + ejector + oxidation contact tower. In addition, there is another process of directly mixing ozone inside the pump, which is the NIKUNI aeration pump process. Below is a brief introduction to the characteristics of the NIKUNI aeration pump and its performance comparison with traditional mixing processes.
Application of NIKUNI Pump in Ozone Water Production
NIKUNI aeration pump is a model of the exquisite combination of NIKUNI industrial pump design technology and precision machining technology. Its unique design and excellent performance provide a more efficient and ideal choice for ozone water treatment technology.
- 1. Characteristics of NIKUNI aeration pump:
◎ High dissolution efficiency
As shown in the figure on the right, there are dozens of radially arranged blades around the impeller of the NIKUNI aeration pump, which generate friction and thrust during the rotation of the impeller inside the pump. The gas-liquid mixture sucked into the pump by negative pressure is vortex pressurized and mixed between each blade. During the process from the inlet to the outlet of the pump, ozone has been uniformly mixed dozens of times, so it can be fully dissolved in water.
◎ Long term performance stability
NIKUNI pump has a simple structure, with no metal friction parts inside except for the mechanical seal. In addition, the pump is made of 304 or 316 stainless steel, and the sealing material is high-quality silicon carbide and PTFE, which has excellent corrosion resistance.
In addition, the low NPSH design of the NIKUNI pump ensures smooth gas suction and mixing, with long-term stable and reliable performance.
◎ Small foot print saves installation space
NIKUNI pump has a reasonable structure and small volume. Even in the production of 50 cubic meters of ozone water equipment, the land area of the NIKUNI aeration device does not take big floor space and the device height can also be small enough. Especially suitable for current equipment renovation and equipment setup in existing factories.
Easy to operate and maintain
NIKUNI aeration device is simple in structure. After adjusting the water volume, ozone generation, oxygen volume, and operating pressure appropriately, it can operate a long time without failure and basically does not require maintenance.
2. Application effect of NIKUNI aeration pump
Based on the output and concentration of the ozone generator, the amount of treated water, the amount of oxygen inhaled, and the water temperature, the dissolution efficiency of ozone in water can reach over 99% by using a NIKUNI pump. Please refer to our company's application test report.
Low operating costs (electricity), users can get more benefits.
Suitable for producing high concentration ozone water
In industries such as sewage treatment and semiconductor cleaning that require the production of high concentration ozone water, traditional processes require repeated mixing and extended contact time to achieve the desired results. As a result, the large amount of ozone generators and large oxidation contact towers increase the cost of the entire treatment equipment, and the equipment's footprint becomes quite large, and the treatment effect is not ideal. The mixing process using a NIKUNI aeration pump can achieve ideal treatment results while improving mixing efficiency and shortening mixing time.
limitations
The gas water mixing ratio of the NIKUNI aeration pump is 1:9, which means that gas takes about 10% of the pump's flow rate and remaining 90% of the flow rate is liquid. Therefore, it is generally only applicable for producing ozone water using pure oxygen sources. This to some extent limits the application of NIKUNI pumps in equipment for producing ozone water from dry air sources.
However, considering that the oxygen purity of the dry air oxygen source is about 21%, and the remaining 79% inevitably transforms into residual nitrogen compounds, it is not suitable for use in pure drinking water (in foreign countries, pure oxygen sources are generally used to produce ozone water). Furthermore, due to the fact that the oxygen purity of dry air sources is more than three times lower than that of pure oxygen sources, the amount of ozone generator required to produce the same amount of water is correspondingly increased, thereby increasing the investment and operating costs of ozone generators.
4. Application fields of NIKUNI aeration pump
NIKUNI pumps have won high praise from ozone users in Japan due to their efficient mixing characteristics and have achieved absolute market share in the Japanese market. Almost all small and medium-sized ozone tax production equipment uses NIKUNI pumps. In recent years, especially in application fields that require high concentration ozone water, especially in the microelectronics industry where chip cleaning requires a concentration close to 200ppm, traditional mixing methods are simply unable to cope, and the only solution is the NIKUNI pump (PTFE coated product).
Since its sale in China, tens of thousands of users (including equipment manufacturers and engineering companies) have adopted NIKUNI aeration pump. A considerable number of users have switched to NIKUNI pumps due to the modification of existing equipment or the inability of traditional equipment to meet quarantine standards. So far, the renovation rate is zero.
5. Scope of Supply
尼可尼泵的供貨范圍0.5-120立方/小時(shí)。單泵或成套設(shè)備供應(yīng)均可。歡迎與我們接洽。
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In the field of traditional water treatment equipment, NIKUNI aeration pump greatly simplifies the process design and overall structure of related equipment with its unique technical features, effectively improving the mixing effect of gas and liquid and increasing the added value of equipment while reducing equipment costs.
NIKUNI Aeration pump can suck in a certain proportion of gas (air, functional gas) while sucking in liquid (water or other liquids). With the high-speed rotation and pressurization process of the impeller, the liquid and gas are evenly mixed and sent into the outlet pipeline of the pump. Due to its structural characteristics, NIKUNI aeration pump is less susceptible to cavitation during gas-liquid mixing and its performance remains stable for a long time during use. Additionally, the operation and maintenance of the pump and related equipment are also more convenient.
The fine bubbles in the water mixed and released by the NIKUNI aeration pump basically reach the micro level (bubbles of 10-30 micron account for an absolute proportion). The dissolved gas saturation tank used with NIKUNI aeration pump is much smaller in size than traditional equipment and generally does not require the use of bubble discharge discs, which can avoid shutdown failures caused by blockage of the discs during use. The gas-liquid mixing efficiency of the NIKUNI aeration pump can reach over 95%, which is higher than conventional gas-liquid mixing processes.
NIKUNI aeration pump can be equipped with various auxiliary accessories according to practical application needs. In some special applications, certain accessories help to make the bubbles released after gas-liquid mixing invisible to the naked eye at the nanoscale, bringing higher added value to equipment manufacturers and end users.
In order to deepen users' understanding of the production of micro bubble water by gas-liquid mixing pumps and the related application fields of aeration pumps, we have collected and organized the following information based on the practical application experience of NIKUNI aeration pumps for reference.
1、 About micro bubbles
There are tiny bubbles in liquids, and bubbles with a diameter below 100 μm are called fine bubbles, while bubbles with a diameter below 100nm are called microbubbles. Due to the fact that the volume of bubbles has reached the molecular level, they possess physical and chemical properties that conventional macroscopic large bubbles do not have, such as an increase in surface area by tens of thousands of times, a rapid increase in dissolved oxygen in water, a small volume with a slow rise rate, the ability to remain in water for a long time, and the ability to adsorb organic matter in water with surface charges.
Micro bubbles released into water generally appear as dense white smoke, while bubbles of nano level released into water cannot be recognized by the naked eye (requiring the use of laser equipment for identification).
2、 Characteristics of micro bubbles
1. Increased surface area
Under the same volume of air, the more bubbles there are, the larger the surface area of the bubbles, and the larger the total area of contact between the bubbles and water. Various biochemical reactions also increase exponentially.
2. Slow ascent speed
The rising speed of bubbles in water is proportional to the square of the bubble diameter. Compared with macroscopic large bubbles, nano size bubbles can remain in water for a long time because their volume has reached the molecular level and their buoyancy effect can be almost negligible. For example, when a bubble with a diameter of 1mm rises at a speed of 6m/min in water, and a bubble with a diameter of 10 μm rises at a speed of 3mm/min in water, the latter is 1/2000 of the former. If considering the increase in specific surface area, the solubility of nano bubbles is 200000 times higher than that of ordinary air.
3. It can automatically increase pressure and dissolve
The dissolution of micro bubbles in water is a process in which the bubbles gradually shrink. The increase in pressure increases the rate of gas dissolution, and with the increase in surface area, the rate of bubble shrinkage becomes faster and faster, ultimately dissolving into water. In theory, the pressure exerted on the bubbles when they are about to disappear is infinite.
dissolution, which can greatly improve the solubility of gases (air, oxygen, ozone, nitrogen, carbon dioxide, etc.) in water.
4. Surface electrification
The gas-liquid interface formed by micro bubbles in water has a greater attraction to anions than cations, resulting in negative charges on the surface of the bubbles. This allows micro bubbles to adsorb organic matter in water and also has antibacterial effects.
3、 Application of Micro Bubble Preparation Equipment
1. Aquaculture
A) Quickly increase dissolved oxygen content
The principle of micro bubble oxygenation is different from the conventional microporous rubber tube oxygenation method. After injecting bubbles into the aquaculture pond, the oxygen concentration in the water rapidly increases, and micro bubbles can diffuse to every part of the pond on their own, resulting in a uniform distribution of dissolved oxygen;
B) Shorten the breeding cycle
Due to the fact that the diameter of micro bubbles has reached the molecular level, they can be directly absorbed by aquatic animal cells, penetrate the cell wall, and act directly on the inside of the cells, thereby improving the metabolism of aquatic products, promoting growth, achieving early release from the pond, staggered listing, and high price sales; This effect also greatly reduces various risks in aquaculture;
According to a report by NHK TV in Japan, the breeding cycle of this fish using oxygen enriched water has been shortened from the usual 24 months to 14 months;
C) Increase breeding density
Due to the ability of bubbles to remain in water for a long time, using bubbles for aquaculture can increase the density of aquaculture under the same conditions. For example, in a water tank with a volume of 2m * 2m * 1.5m, 1.5 times high-density bream aquaculture is carried out. After 5 minutes, the oxygen in the water does not decrease but increases, and the oxygen concentration increases from 7.6mg/L to 7.9mg/L. Within 25 minutes, the oxygen concentration gradually increases to 8.3mg/L;
D) Save medication costs
Nano bubble water is fundamentally different from oxygen powder (calcium peroxide) sold in the market, reducing the cost of repeated dosing for farmers. At the same time, due to the significant increase of bubbles in the water, the growth of anaerobic bacteria can be suppressed to a certain extent, keeping the water clean, reducing the investment cost of disinfectants and avoiding secondary pollution of aquatic product growth by disinfectants;
E) Leading technology
In nanobubble water, the number of bubbles per milliliter has increased by at least one order of magnitude, reaching up to 4.0 × 107 nanobubbles per milliliter, far superior to inefficient production methods such as ultrasound or electrolysis;
F) Do not add any chemicals
It can quickly increase the dissolved oxygen in water in a short period of time. The process of injecting bubbles into water is 100% physical reaction, without adding any chemical substances, and has zero pollution to aquatic products and the surrounding environment; The micro bubble generation device is made of food grade stainless steel, which is corrosion-resistant and durable, and has no effect on the growth of aquatic products.
2. Agricultural hydroponic cultivation
Based on the same principle, irrigating between ridges or using drip irrigation pipes to apply water containing fine bubbles, nutrients, or ozone gas during the planting process of agricultural fruits, vegetables or grain crops can significantly increase the supply of oxygen nutrients to crop roots or improve sterilization effectiveness to protect plants from disease.
Taking the cultivation of ginger or strawberries as an example, when farmers apply liquid containing microbubbles to the roots of crops, the roots and stems of the crops become much thicker than before, with stronger disease resistance and better growth.
3. Food preservation
In terms of food preservation applications, the main methods are to sterilize fruits, vegetables, raw meat, and fresh fish with ozone water or to fill the storage tank with nitrogen gas infused water containing nanoscale nitrogen to isolate the air, ensuring that the preservation time of these fresh fruits, vegetables, fresh meat, and fresh fish is extended several times compared to the conventional situation without adding ozone or nitrogen. This not only ensures the reliable and fresh quality of the products delivered to users, but also helps businesses avoid economic losses caused by improper preservation.
4. Ozone water sterilization and disinfection
Ozone gas produced through discharge tubes or electrochemical methods is a broad-spectrum strong oxidizing bactericide. Functional micro odorous oxygen infused water can achieve harmless non thermal sterilization. Due to its strong oxidizing and sterilizing ability without secondary residue, it has been widely used in drinking water, medical pure water treatment, high-rise secondary water supply sterilization, swimming pool water treatment, aquaculture water treatment, circulating cooling water treatment, industrial wastewater and sewage treatment for many years.
Ozone micro bubble water is also a widely used disinfection and sterilization medium obtained by uniformly dissolving ozone gas into water in the form of micro bubbles using a gas-liquid mixing pump. It can replace various disinfection and sterilization agents.
Due to limited space and the fact that common knowledge about ozone applications can be obtained online, the specific application of ozone water will not be elaborated here.
5. Wastewater and sewage treatment
A) Quickly increase the dissolved oxygen in water
When a large number of micro nano level bubbles are injected into water, the dissolved oxygen level of the water can be rapidly increased, promoting the growth of aerobic bacteria. Aerobic bacteria can quickly decompose organic matter in water; Simultaneously inhibiting the growth of anaerobic bacteria, effectively controlling water deterioration, and maintaining water cleanliness. Compared with conventional micro porous bubble oxygenation methods, nano o bubbles do not quickly float and dissipate, but can remain in water for a long time, greatly improving water quality and achieving the effect of water purification;
B) Quickly purify water quality and improve transparency
According to environmental requirements, air, oxygen, or negative oxygen ions can be injected into water. When negative oxygen ions are injected into water, the effect of water purification can be achieved within 60 minutes. Due to its extreme instability, ozone can decompose into oxygen on its own within 30 minutes. As ozone is a substance that exists in nature, it will not have any impact on the surrounding environment and human body in outdoor environments;
C) Adsorption and Separation of Organic Compounds in Water
Research has found that due to the surface charge of nano bubbles, they can adsorb organic matter in water, causing them to float or sink, thereby achieving rapid cleaning; It can also reduce eutrophication caused by organic matter deposition, effectively control water pollution, oil pollution and other problems;
D) No need to add any enzymes or nutrients
Compared with conventional river aeration and oxygenation methods, the NIKUNI aeration pump discharges a large number of micro bubbles into the river water, prolonging their retention in the water by many times. At the same time, it can reduce the dosage of chemicals, lower the cost of chemical input, and reduce the secondary pollution and post-treatment costs of chemicals on the environment;
6. High end leisure bathing facilities
NIKUNI aeration pump has been widely used in the field of high-end leisure bathing facilities. The main applications include:
A) Milky bath
Release micro bubble water in the bathtub or bath, turning the bath water into a thick milky white color like milk, allowing the bather to feel the refreshing sensation when the micro bubbles come into contact with the skin in the water.
In some high-end bathing facilities, merchants also use the milky white water surface of the bathhouse as a screen, and use projection devices to cast beautiful videos on the water surface in a dim atmosphere accompanied by soft music, allowing bathers to relax and feel the wonderful atmosphere of a fairyland;
B) Functional water fitness bath
Release micro carbonated water or a certain concentration of hydrogen water in a bathtub or bath, allowing bathers to enjoy the maintenance and health benefits of different media of micro functional micro carbonated water on human body.
C) Comfortable and Enjoyable Bath
Project LED lights of different colors in the micro bubble water bath to create a beautiful and enjoyable atmosphere with ruby, sapphire, and emerald tones, allowing bathers to enjoy the pleasure of bathing and maintain their skin while feeling the beauty of time;
With the promotion and popularization of the application technology of the NIKUNI aeration pump, many domestic equipment manufacturers have also begun to promote similar leisure and entertainment bathing facilities.
NIKUNI aeration pumps have a wide range of product specifications, with materials such as cast iron and stainless steel corresponding to various applications. At the same time, NIKUNI also provides technical support related to pump applications to users. You are welcome to purchase NIKUNI products.
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一． CHARACTORISTICS:
- The most significant feature of the NIKUNI multi-phase flow mixing pump is that it sucks in liquid and other different media that need to be mixed at the same time and have them uniformly mixed and blended by the pump impeller and pressurized and sent to the outlet pipeline. The conveying pressure generated inside the pump delivers the finely mixed medium to a distant point of use.
- NIKUNI multi-flow mixing pump is multifunctional and compared with traditional equipment in the field of water treatment applications gas ejectors, air compressors, large dissolved gas tanks and discharge discs become unnecessary. In the application fields of chemical and other industries it can replace reaction tanks, mixing and blending equipment and complex pipelines, valves, and control systems, greatly simplifying the application process and equipment structure.
- The use of NIKUNI multi-phase flow mixing pumps helps to reduce equipment power consumption, minimize equipment failures, improve mixing efficiency, and make related equipment performance more stable and reliable.
- Compared with traditional equipment, NIKUNI multi-media mixing pump helps reduce initial investment costs, long-term operating costs and maintenance costs.
Product Applicability
1. Liquid to liquid mixing 1. Mixing of liquid and gas (dissolution, reaction, neutralization)
◎ Mixing and dissolution of air
Generate fine bubbles for use in dissolved air flotation, product cleaning or entertainment facilities, etc.
◎ Mixing and dissolution of oxygen Aquaculture, hydroponic cultivation of crops, oxygenation, etc
◎ Ozone gas dissolution to water
Aquaculture, hydroponic cultivation of crops, oxygenation, etc
◎ Ozone gas dissolution to water
Production of ozone water (sterilization, removal of organic matter), etc
Mixing and dissolution of various gases
Producing functional beverage water such as oxygen rich water and hydrogen rich water
1. Liquid to liquid mixing (mixing of immiscible liquids)
Emulsification of water and fuel oil
◎ Polymer flocculant dilution
◎ Chemical process application
Reaction, neutralization, dispersion, emulsification, homogenization, etc
33. Mixing of powder and liquid(dispersion, dissolution)
●Food processing industry
Defatted milk powder, wheat flour, skimmed milk powder, wheat flour, corn starch, soy milk, etc
◎ Chemical raw materials
Coagulants, polymers, calcium carbonate, etc
3、 Practical application cases
◎ Water+air (oxygen)
Hydroponic cultivation of crops and plants, providing water and oxygen supply to the roots of plants grown in greenhouses
Iron removal from well water
Oxygen supply to aquaculture ponds, cages, and ornamental fish tanks
Activation of aerobic bacteria in the purification tank and aeration tank filled with acetic acid
Circulating water for spraying workstation, oxygenation and anti-corrosion of cutting fluid for cutting machine tools
.
◎ Water+Ozone
Sterilization of fruits, vegetables, river seafood, meat, and kitchenware
Sterilization of circulating water such as drinking water, beverages, swimming pools, and bathhouses
Removing chemical residues in semiconductor production processes
Sterilization and cleaning in the production process of biologics and pharmaceuticals
Deodorization of pig pens, chicken coops, various exhaust devices, etc
Sludge reduction during biological treatment process
◎ Seawater+Air (Oxygen)
Promote growth during the breeding process of flounder, oysters, fresh shellfish, etc
◎ Water+Carbonated Gas
Neutralization of chemical solution during alkaline waste liquid treatment and boiler descaling process
Promotes the growth of aquatic plants Large ornamental fish tank
.
.
◎ Water+Hydrogen
Reduce chemical night residues in semiconductor cleaning process
◎ Seawater+Ozone
Sterilization of seawater, shellfish, seagrass, fishing gear, containers, etc
◎ Chemical liquids + various gases
Reaction and coincidence inside the pipeline (such as photocatalyst, calcium carbonate, etc.)
◎ Water+Nitrogen
remove dissolved oxygen from ultra pure water and nitrogen for boiler water supply
◎ Powder+Liquid (Food Processing)
Production of skimmed milk powder, wheat flour, corn starch, soy milk, etc
◎ Powder+Liquid (Chemical Raw Materials)
Production of coagulants, polymers, calcium carbonate, etc
Conclusion：
NIKUNI multi-phase flow mixing pump is suitable for various applications such as gas-liquid mixing, liquid-liquid mixing, powder liquid mixing, etc. Using a NIKUNI mixing pump to add various functional gases such as oxygen, nitrogen, ozone, carbon dioxide, hydrogen, chlorine, etc. to fresh water, seawater, and chemical liquids, allowing them to fully dissolve and mix with the liquids, can add new value to the water and liquids. It also plays a positive role in the emulsification of liquids and the refining of fuels. Can replace static mixers. It plays a role in the mixing process of powder and liquid in food production and chemical raw material production.
]]>1 選型要點(diǎn)
1．1主要泵型及特點(diǎn)
根據(jù)不同的工藝路線，煉油廠主要裝置一般為常壓蒸餾、減壓蒸餾、催化裂化、加氫裂化、延遲焦化等。
按上述工藝流程，煉廠比較重要的泵一般為初餾塔底泵、常壓塔底泵、減壓塔底泵、油漿泵、加氫進(jìn)料泵、出焦水泵(除焦泵)等，這些泵主要輸易燃、易爆或有毒等危險(xiǎn)液體，有的介質(zhì)溫度高達(dá)400℃以上，有的還含有固體顆粒，因此要求材料具有良好的耐腐蝕、耐磨蝕能力，泵還必須具有高的可靠性，能夠長期安全運(yùn)轉(zhuǎn)。
1．2選型步驟
1．2．1泵型式的確定
在煉廠設(shè)計(jì)過程中，所需主要泵型式大都已被指定，如API610標(biāo)準(zhǔn)中編碼OH（懸臂式)、BB(兩端支承式)、VS(立式懸吊式)等，因此，一般不需要再對泵型式進(jìn)行選擇。
1．2．2流量—揚(yáng)程
? ? 流量和揚(yáng)程是選泵的主要依據(jù)。在詢購單中一般會(huì)提出最小連續(xù)流量、正常流量、額定流量三個(gè)流量。按API610標(biāo)準(zhǔn) 要求選泵時(shí)，泵的額定工況點(diǎn)應(yīng)選在泵最佳效率點(diǎn)(BEP)的右側(cè)，正常工況點(diǎn)在最佳效率（BEP）的左側(cè)（圖1)，而泵的實(shí)際最小流量應(yīng)不大于所要求的最小連續(xù)流量。應(yīng)按額定工況點(diǎn)選取揚(yáng)程，即詢購單中要求的揚(yáng)程是額定流量點(diǎn)對應(yīng)的揚(yáng)程，并且選型時(shí)揚(yáng)程不加裕量。
詢購單上一般要求泵要具有平坦連續(xù)上升型性能曲線,不許有駝峰,此外從額定工況點(diǎn)到關(guān)死點(diǎn)揚(yáng)程上升不超過20％。
有的工程公司選泵時(shí)要求泵的額定工況點(diǎn)應(yīng)選在泵最佳效率點(diǎn)(BEP)的左側(cè)(圖2)，在選型時(shí)應(yīng)該根據(jù)不同的要求給予滿足。
1.2.3 氣蝕余量(NPSHr)
NPSHr是泵的一個(gè)重要性能指標(biāo)，在詢購單中對此有具體的數(shù)值要求,并且有時(shí)提出從小連續(xù)流量到額定流量區(qū)域內(nèi),.NPSHa-NPSHr≥0.8米等要求,目的是確保泵在運(yùn)行中不發(fā)生汽蝕,在選型時(shí)應(yīng)特別注意。降NPSHr的措施,如降低轉(zhuǎn)速、選擇NPSHr性能好的葉輪、增加誘導(dǎo)輪等。但在實(shí)際項(xiàng)目
中，有時(shí)設(shè)計(jì)單位提出的NPSHr值非?？量蹋瑓⑴c投標(biāo)幾個(gè)制造廠都不能滿足NPSHr要求,這時(shí)應(yīng)實(shí)事求事的向設(shè)計(jì)單位說明,采取措施重新選型或調(diào)整設(shè)計(jì)。
1.2.4 材料
煉油廠用泵過流部件一般都是標(biāo)準(zhǔn)材料制造,只要按設(shè)計(jì)詢購單要求及API610規(guī)范所列的材料系列選取即可。常底泵、初底泵、減底泵、進(jìn)料泵、出焦水泵等對材質(zhì)沒有特殊的要求，一般為APl610標(biāo)準(zhǔn)中S系列或C系列都可以。比較特殊的是催化裂化工藝流程中的油漿泵，除滿足性能等要求外，還需要解決高溫工況下耐磨的難題，可選用抗磨材質(zhì)或在泵的易磨損部位采取一定的耐磨措施，提高性。
對于高壓泵承壓泵體，如進(jìn)料泵外筒體，所選擇殼體材料一定要符合該泵的溫度-壓力關(guān)系變化要求，圖3為某泵的溫度-壓力變化曲線。國內(nèi)自己設(shè)計(jì)的泵往往缺乏這方面的資料，因此要特別注意。另外，對于不同材料的軸，要特意注意該軸所允許配帶的最大電機(jī)功率，國外泵一般是給定不同材料軸的最大許用P（kW)／n(r／min)值，根據(jù)該值，可確定每種材質(zhì)軸可配帶的電機(jī)最大功率。
1．2．5 密封及輔助系統(tǒng)
密封及輔助系統(tǒng)是泵的重要組成部分，對泵的可靠運(yùn)行起著決定性的作用，API682標(biāo)準(zhǔn)選取密封方案。設(shè)計(jì)院在詢購單中一般不會(huì)對密封作出具體的要求，而是要求泵制造商密封廠來根據(jù)工況要求確定詳細(xì)的密封方案。密封方案的確定，需要依靠經(jīng)驗(yàn)的地方很多，對復(fù)雜的工況條件，各公司選擇的方案可能會(huì)有很大的不同。有的公司為保證安全，使得所選的密封方案功能過剩，結(jié)果是報(bào)價(jià)提高，可能使在商務(wù)投標(biāo)中處于不利的地位。我人的看法是在保證安全可靠的前提下，避免軸封系統(tǒng)功能過剩。此外世界上知名的封制造廠，如德國BURGMANN公司、英國JOHN CRANE公司，對各行業(yè)不同介質(zhì)條件所選機(jī)封及系統(tǒng)，都有許多成熟的經(jīng)驗(yàn)，地選擇密封方案時(shí)可充分征求密封制造廠的意見，力爭選出較合理的密封方案。
1．2．6電機(jī)、汽輪機(jī)等驅(qū)動(dòng)機(jī)
電機(jī)的選型也很重要，在設(shè)計(jì)詢購單中往往已選定了要求的電機(jī)功率、電壓、防爆、防護(hù)等級等。因而對泵的效率也就有了要求，如果泵效率較低，可能發(fā)生指定電機(jī)功率不夠用的情況。
石化廠出于節(jié)能和能量回收利用的需要，有的泵采用液力透平機(jī)驅(qū)動(dòng)或蒸汽輪機(jī)驅(qū)動(dòng)。目前，國內(nèi)石化廠選用液力透平作為泵驅(qū)動(dòng)機(jī)的比較多，而使用蒸汽輪機(jī)來驅(qū)動(dòng)泵的很少，主要原因是目前國內(nèi)小蒸汽輪機(jī)(2000kW以下)市場基本上是空白，而從國外引進(jìn)價(jià)格比較昂貴，一定程度上影響了小蒸汽輪機(jī)作用泵用驅(qū)動(dòng)機(jī)械的推廣。但石化公司普遍希望在石化公司內(nèi)推廣使用小蒸汽輪機(jī)來替代一部分泵用電機(jī)，因石化工廠一般都有自備電廠，有豐富的各種壓力等級的熱蒸汽資源。
2 關(guān)于數(shù)據(jù)單的建議
各工程公司、專利商（如UOP-美國環(huán)球油品公司）一般都有本公司專用的泵數(shù)據(jù)單，泵制造廠或銷售商最好直接使用詢購單中提供的數(shù)據(jù)單。現(xiàn)在各泵制造廠在獲得詢購單后又往往用自己公司的泵數(shù)據(jù)單重新謄寫一遍，除麻煩和內(nèi)容出錯(cuò)外，技術(shù)交流時(shí)非常不方便。因?yàn)椴煌镜谋脭?shù)據(jù)單格式、順序、內(nèi)容等并不完全相同。反之如果直接使用詢購單中的數(shù)據(jù)單，在技術(shù)審查或技術(shù)交流時(shí)，對設(shè)計(jì)院確認(rèn)泵制造廠回應(yīng)技術(shù)詢購書的要求，會(huì)非常直觀清晰，一目了然，便于雙方進(jìn)行技術(shù)交流和確認(rèn)。
3 關(guān)于API610標(biāo)準(zhǔn)
API610標(biāo)準(zhǔn)是目前國際上公認(rèn)的關(guān)于煉油廠用泵設(shè)計(jì)驗(yàn)收最權(quán)威的技術(shù)規(guī)范，在中國也得到廣泛應(yīng)用。按API610規(guī)范設(shè)計(jì)制造的泵通常稱API泵。我國的石化也大多參考該標(biāo)準(zhǔn)設(shè)計(jì)制造。國內(nèi)較大的APl泵制造廠都有很多系列性能完善的引進(jìn)技術(shù)產(chǎn)品，因此在參與項(xiàng)目時(shí)只要根據(jù)要求直接選型即可，而無須重新設(shè)計(jì)，但有時(shí)需要在局部做一些改進(jìn)以滿足需要。
API610標(biāo)準(zhǔn)也不斷修訂和完善之中，一般7-8年左右時(shí)間更新一次，不同版本的部分內(nèi)容會(huì)有一些變化，因此在應(yīng)用APl610規(guī)范過程中要靈活應(yīng)用，對一些非原則性條款不一定完全照搬。
作為泵制造廠，在產(chǎn)品的設(shè)計(jì)宣傳中要實(shí)事求事，沒有必要過于追求所謂的APl610最新版本。不要?jiǎng)虞m就宣稱自己的產(chǎn)品完全符APl610標(biāo)準(zhǔn)，以免在技術(shù)交流或驗(yàn)收時(shí)給自己帶來麻煩。事實(shí)上哪個(gè)泵制造廠都難以做以做出所謂的百分之百APl610泵。
泵選型看似簡單，其實(shí)不然。要作出好的選型，不是一件很容易的事，往往需要依據(jù)很多的實(shí)踐經(jīng)驗(yàn)，涉及泵、密封及輔助系統(tǒng)、高速系統(tǒng)、潤滑系統(tǒng)、冷卻系統(tǒng)、材料、電機(jī)、連軸節(jié)、電器、儀表、工藝流程等多方面的知識(shí)，有時(shí)需要設(shè)計(jì)單位、泵制造廠和用戶在一起討論交流磋商，確定泵的最終選型方案。
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