浅谈磁力泵与屏蔽泵

译文:
随着人们环保意识的日益增强和环保法规的逐步健全,泵泄漏的问题越来越引起人们的重视。从理论上讲,杜绝泵泄漏xxx的措施就是采用无密封泵。《浅谈磁力泵与屏蔽泵》一文着重阐述了两类无密封泵即磁力驱动泵、屏蔽泵的基本原理、工作性能、适用范围及其优缺点,并对两类泵作了对比分析。 多年来,常规的有密封泵一直是石化工业的主力装备。这种泵上装有各种各样的密封,从填料密封直到复杂的双端面机械密封。有密封泵的主要优点是单位成本低,设计上的通用性,用户对此维护方式已经习惯。其缺点是,该密封必须产生泄漏来润滑密封面。填料密封的泄漏量一般为3~80mL/h,制造良好的机械密封仅有微量泄漏,其泄漏量为0.01~3mL/h。如果密封出事故,则输送介质就会泄漏到大气中,从而危害人身和环境。此外,虽然目前机械密封及其精巧的辅助系统已经变得越来越复杂,但在延长密封使用寿命方面所取得的进展始终不令人满意。因此,一种既可行又重要的选择方案就是采用一种不需要轴封的离心泵即无密封泵。相比之下,无密封泵可以大大减轻或xx这种灾难性事故的危害并大大延长使用寿命。无密封泵主要包括磁力驱动泵和屏蔽泵,结构上只有静密封而无动密封,用于输送液体时能保证一滴不漏。 1.磁力驱动泵 磁力联轴器传动泵(简称磁力驱动泵)最早是在1947年由英国HMD公司的Geoffrey Howard研制成功的。几年后西德的Franz Klaus也相继开发成功。{zx0}使用磁力驱动泵的两家公司是英国的帝国化学工业公司和德国的拜尔化学公司。开发磁力驱动泵的最初目的是为了保护从事化工、核动力、国防等工业现场人员的安全和健康。20世纪70年代中期以后由于稀土钴(1978年)、最强有力的钕铁硼(1983年)等新一代永磁铁和碳化硅轴承技术的开发使磁力驱动泵的技术水平有了极大的提高。据国外样本和文献资料显示,磁力驱动泵的流量现在可达1150m3/h;扬程达500m;介质温度范围-120℃~450℃;粘度极限100~200cp;介质中磨蚀性固体颗粒含量可达1.5%(按重量),固体颗粒粒度可达100μm;采取特殊措施后,泵能输送含20%不溶性固体物的渣浆,固体物直径可达20mm;系统压力可达450bar。磁力驱动泵还适应于机械密封很难胜任的高真空使用条件。技术上的这些突破和其它改进措施,使磁力驱动泵的可靠性和经济性有了惊人的提高。对磁力驱动泵和机械密封泵的可用率和易修性的调查表明,有密封泵的损坏率和故障率都明显高于磁力驱动泵。例如在400℃的热液泵上的机械密封平均寿命为6个月,而磁力驱动泵能运转多年,惟一需要的维护只是对泵和电机的外部轴承进行正常的润滑。在化工领域中获得的大量经验已使人们得出这样的结论:磁力驱动泵已经发展成为许多流程装置中最经济的解决办法。因此,磁力驱动泵使用的增多已不仅仅是因为一个可靠的环境因素,而且还有大幅度减少运行、维修费用的经济因素。其应用范围已从输送危害性液体和贵重液体扩大到需要长寿命、维护少的普通用泵场合,例如远洋船舶上因维护费用高而用磁力驱动泵来输送空调系统用冷水。最近十年来磁力驱动泵的应用急剧增长,已经成为各种应用领域中的常见装备。磁力驱动泵现在可以满足无密封泵全部应用领域的90%。 磁力驱动泵是利用磁体能吸引铁磁物质以及磁体或磁场之间有磁力作用的特性;而非铁磁物质不影响或很少影响磁力的大小,因此可以无接触地透过非磁导体(隔离套)进行动力传输,这种传动装置称为磁性联轴器。电动机通过联轴器和外磁钢联在一起,叶轮和内磁钢联在一起。在外磁钢和内磁钢之间设有全密封的隔离套,将内、外磁钢xx隔开,使内磁钢处于介质之中,电动机的转轴通过磁钢间磁极的吸力直接带动叶轮同步转动。其主要优点:由于传动轴不需要穿入泵壳,而是利用磁场透过空气间隙和隔离套薄壁传动扭矩,带动内转子,因此从根本上xx了轴封的泄漏通道,实现了xx密封;传递动力时有过载保护作用;除磁性材料与磁路设计有较高要求外,其余部分技术要求不高;磁力驱动泵的维护和检修工作量小。其主要缺点:磁力驱动泵的效率比普通离心泵低;对防单面泄漏的隔离套的材料及制造要求较高;磁力驱动泵由于受到材料及磁性传动的限制,因此国内一般只用于输送100℃以下、1.6MPa以下的介质;由于隔离套材料的耐磨性一般较差,因此磁力驱动泵一般用于输送不含固体颗粒的介质;联轴器对中要求高,对中不当时,会导致进口处轴承的损坏和防单面泄漏隔离套的磨损。 2.屏蔽泵 屏蔽泵属离心式无密封泵,泵和驱动电机都被封闭在一个被泵送介质充满的压力容器内,此压力容器只有静密封。这种结构取消了传统离心泵具有的旋转轴密封装置,能做到xx无泄漏。屏蔽泵把泵和电机联在一起,电动机的转子和泵的叶轮固定在同一根轴上,利用屏蔽套将电动机的转子和定子隔开,转子在被输送的介质中运转,其动力通过定子磁场传递给转子。其主要优点:①与有密封泵相比,省去了维修和更换密封的麻烦,也省去了联轴器,零件数量少(只有机械密封泵的30%左右),可靠性高。无滚动轴承和电机的风扇,不需要加润滑油,且运转平稳、噪音低。可配置轴承磨损监视器,检测轴承的磨损情况。②结构紧凑,占用空间小,对底座和基础的要求低,没有联轴器的对中问题,安装容易且费用低。日常维修工作量少,维修费用低。③能在真空系统或“真空”与“正压”交替运行的情况下正常运转而无泄漏。可以在高真空度情况下直接从真空槽中把物料送至其他容器中。使用范围广,对于高温、高压、极低温、高熔点等各种工况均能满足要求。其主要缺点:①由于采用滑动轴承,且用被输送的介质润滑,故对润滑性差的介质就不适宜采用屏蔽泵输送。一般适合于屏蔽泵的介质粘度范围为0.1~20cP。②屏蔽泵的效率通常低于有密封的离心泵。但在中、小功率的情况下,与双端面密封泵相比,后者由于增加了冷却和冲洗系统的功率消耗,故总效率相差不大。③离心泵运行时,要求流量应高于最小连续流量。对屏蔽泵这点尤其重要,因为在小流量工况下,泵效率较低且会导致发热,使流体蒸发而造成泵干转,引起滑动轴承的损坏。 3.磁力驱动泵与屏蔽泵的比较 在过去十年中,磁力驱动泵已成为广大应用领域中的常见装备。相比之下,屏蔽泵已被看作是一种价格更高、更特殊的泵,多数情况下只在有专门订货时才设计制造。尽管这种看法随着标准化屏蔽泵系列的出现而正在变化,但屏蔽泵在市场中仍只占相当小的份额。 一般来说,无密封泵的可靠性等同于或优于相当的有密封泵。但是这两种泵都会因使用不当(特别是干转和偏离设计点运转)而易遭损坏。用输送介质润滑轴承的无密封泵在长时间的干转后才会发生轴承磨损。在缺乏运行监控情况下,这种磨损是看不见的,在某些情况下可能导致泵损坏和密封套的破裂。标准的磁力驱动装置在损坏情况下会使液体泄入联轴器体内,并且通过联轴器轴承泄漏到外界大气中。这种泄漏通常由于液体必须流经曲折通路而受到节制,一般不会造成严重后果。这种标准的磁力驱动装置还可以作很大改进以避免泄漏,改进方法是采用通气口来防止联轴器体内的压力增大和采用辅助的(驱动装置)轴封来防止泄漏。相比之下,屏蔽泵会使泄漏液体密封在电机体内,并防止进一步外泄。不过要把液体密封住,只有在严密注意压力容器(电机壳)到接线盒之间的电缆接头的情况下才有可能。这个部位历来是屏蔽泵的惟一弱点。设计不良会使第二道(指电机壳)密封不起任何作用。即使密封套万一损坏,磁力驱动泵可以xx得到清理,而且未受损坏的零件可以重新使用。如果必要,这种维修在现场就可进行。而泄漏到屏蔽泵电机体内的液体会使绕组损坏。虽然某些泵型具有可拆卸的定子结构,但大部分屏蔽泵都是采用密封式电机或具有焊接结构,这就需要送到工厂去维修或者重新更换一个昂贵的体内部件。 对于标准磁力驱动泵,不需要批准危险使用区,而屏蔽泵则需要合格证。在许多情况下这种合格证在欧洲各国也相互不一致,可能需要增设运行工况监控装置,如,需要确保流程液存放的液位探测器。对于标准形式的屏蔽泵,其温度局限在约100℃以内。决定因素是电机绕组采用的绝缘等级,为了克服这个问题,电机装有独立的冷却回路,从而增加了管路、冷却液源、泵和热交换器的额外费用。标准的同步磁力驱动泵可以在约400℃温度下运转。 总的来说,磁力驱动泵可以满足无密封泵全部应用领域的90%。这种泵技术规格齐全,价格经济,交货期短,使用方便,维修时不需要电工参与,而且可以与普通的有密封泵直接互换。屏蔽泵结构复杂,价格昂贵,通常不能满足常规的标准。此外,密封零部件牵涉到维护问题,多工种安装问题,以及交货期长等问题,这些都使得屏蔽泵只能应用在磁力驱动泵不能满足的、危险程度很高的各种边缘应用领域。显尔易见,这两种泵虽然同时占有市场,但磁力驱动泵将会占领更大的市场份额,而成为未来各种环保、安全工业的主力装备。 在国内,由于国人的环保意识尚不是很强,环保法规还不够健全,再加上执行力度也不够,人们对泵泄漏的问题普遍重视不足。从而使国内泵制造厂对如何{zd0}限度地减少泵(尤其是工业用泵)泄漏的研究投入很少。致使国产无密封泵(包括磁力驱动泵及屏蔽泵)的研制、开发水平与国际先进水平相比有较大差距。随着我国加入WTO,以及最近五年优先发展环保产业的战略方针的提出,可以预见,大力发展无密封泵,将会成为今后我国工业用泵的一个发展趋势。

“ On the magnetic shielding pump pump ”是由提供的国际水泵新闻,译文仅供参考。另外,中国磁力泵网还提供相关产品搜索:、、、、等。


 

原文:
With the people's growing awareness of environmental protection and environmental laws and regulations have been gradually perfected, pump leakage problems are becoming increasingly attracted attention. In theory, put an end to pump the most effective measure is to leak-free seal pump. "On the magnetic pump and shield pump" a paper focusing on the two types of non-sealed magnetic drive pump that pumps, pump shield the basic principles of performance and scope of application, advantages and disadvantages, and made a comparative analysis of two types of pumps. Over the years, conventional sealed pumps have been the main equipment, the petrochemical industry. This pump is equipped with a wide variety of seals, from the packing seal until the complex double-face mechanical seal. The main advantage of a sealed pump unit cost is low, design versatility, users have become accustomed to this way of protecting. The disadvantage is that the seal must generate leakage to lubricate the sealing surface. Packing seal leakage is generally 3 ~ 80mL / h, making a good mechanical seal only micro-leakage, the leakage amount of 0.01 ~ 3mL / h. If you seal an accident, then the transmission medium will leak into the atmosphere, thereby jeopardizing the physical and the environment. Moreover, although the auxiliary mechanical seal and its sophisticated systems have become increasingly complex, but in extending the seal life of the progress achieved in the area has always been unsatisfactory. Therefore, a both feasible and important option is to use a centrifugal pump shaft seal does not require that the non-sealed pumps. In contrast, non-sealed pumps can greatly reduce or eliminate such hazards catastrophic incidents and greatly extend the service life. No sealed magnetic drive pump includes pump and shield pump, structure, only a static seal with no dynamic seal for the transmission fluid does not leak when you can guarantee a drop. 1. Magnetic Drive Pump Magnetic coupling drive pump (magnetic drive pump for short) was first in 1947 by the British HMD's Geoffrey Howard successfully developed. A few years later West Germany's Franz Klaus also have developed. The first use of magnetic drive pump 2 is Britain's Imperial Chemical Industries and Germany's Bayer chemical company. Development of magnetic-driven pump was originally designed in order to protect the chemical, nuclear power, defense and other industrial on-site personnel safety and health. The 20th century, since the mid-70s because of rare-earth cobalt (1978), the most powerful NdFeB (1983), such as a new generation of permanent magnet and silicon carbide bearing technology development so that the level of magnetic drive pump technology has greatly improved . According to the foreign samples and literature data show that the flow of magnetic drive pump is now up to 1150m3 / h; head up to 500m; medium temperature range of -120 ℃ ~ 450 ℃; viscosity limit of 100 ~ 200cp; medium abrasive solids content of up to 1.5% (by weight), solid particle size of up to 100μm; take special measures, the pump can transport with 20% insoluble solids of the slurry, solids diameter 20mm; system pressure up to 450bar. Magnetic drive pump mechanical seal is also very difficult to competently adapt to the high-vacuum conditions of use. These technological breakthroughs and other improvements, so that magnetic force driving pump reliability and economy has been an alarming increase. Pairs of magnetic drive pumps and mechanical seal pumps repair and easy availability of research has demonstrated that the failure rate of pump seals and failure rates are significantly higher than magnetic drive pumps. For example, at 400 ℃ heat pump mechanical seal on the average life expectancy of 6 months, while the magnetic drive pump can be operated for many years, the only maintenance required is an external pump and motor bearing lubrication normal. In the chemical industry gained considerable experience has enabled people to come to this conclusion: magnetic drive pump has developed into a number of flow devices, the most economical solution. Thus, the increased use of magnetic drive pumps have been not only because a credible environmental factors, but also significantly reduce operating and maintenance costs of the economic factors. Range of applications from transport hazardous liquids and precious liquid to expand the need for long-life, low maintenance pump ordinary occasions, such as ocean-going ships on the high maintenance costs due to magnetic-driven pumps used to transport air-conditioning system with cold water. Magnetic drive pumps over the last decade the application of rapid growth, it has become common in a variety of applications and equipment. Magnetic drive pump is now to meet the non-seal pumps 90% of all applications. Magnetic drive pump is the use of magnets to attract ferromagnetic materials and magnetic force between the magnets or magnetic field effect properties; rather than the ferromagnetic material does not affect or have little effect on the size of the magnetic force can therefore be non-contact through the non-magnetic conductor (isolated sets) for power transmission, such transmission is called magnetic coupling. Motor through the coupling and the outer magnet in conjunction with the impeller and inner magnet linked. Magnet between the outer and inner magnet was equipped with separate sets of sealed, will be inside and outside the magnet completely separated, so that inside the magnet in the media among the motor shaft through the magnet pole of attraction between the impeller directly driven synchronous rotation. The main advantage: As the pump shaft do not penetrate the shell, but to use the magnetic field through a thin air gap and isolated sets of drive torque to drive within the rotor, thus fundamentally eliminate the shaft seal leakage channels to achieve a complete Seal; transfer power from time to time overload effect; In addition to magnetic materials and magnetic circuit design has high requirements, the rest of technology, not ask for much; magnetic drive pump maintenance and repair workload of the small. The main drawback: magnetic drive centrifugal pump more efficient than ordinary low; right-sided anti-leakage isolation sets of materials and manufacturing requirements is higher; magnetic drive pumps and magnetic properties of materials due to transmission limitations, and therefore generally used only for delivery of domestic below 100 ℃, 1.6MPa the following media; isolated sets of materials, the wear resistance due to the general poor, so magnetic drive pumps are generally used for conveying the medium does not contain solid particles; coupling pairs in high demand right is not the time, will lead to the entrance bearing damage and anti-leakage isolation sets of one-sided wear. 2. Canned Motor Pump Shield is a centrifugal pump seal-free pump, pump and drive motor are enclosed in a medium filled by pumping the pressure vessel, this pressure vessel is only static seal. This structure eliminated the traditional centrifugal pump with a rotary shaft seals, can do completely without leakage. Canned pump to pump and motor in conjunction with, the motor rotor and pump impeller fixed on an axis with the use of mask sets will be separated from the motor rotor and the stator and rotor have been delivered in the medium run, its power through the stator magnetic field passed to the rotor. The main advantages: ① Compared with the sealed pump, eliminating the trouble of maintenance and replacement of seals, but also eliminating the coupling, a small number of parts (only mechanical seal pumps about 30%), and high reliability. No Rolling and motor fans, do not need to add oil, and the smooth operation, low noise. Bearing wear monitor can be configured to detect bearing wear. ② compact, taking up little space on the base and foundation that require low, there is no problem in the coupling of the installation easy and low cost. Less routine maintenance, low maintenance cost. ③ in a vacuum system or the "vacuum" and "pressure" alternative case of normal operation without leakage. In high-vacuum conditions can be directly sent from the vacuum slot of materials in other containers. The use of a wide range, for high-temperature, high pressure, very low temperatures, high melting point and other conditions can meet the requirements. The main drawback: ① As a result of sliding bearings, and transport used by the media lubrication, and therefore poor lubrication medium on the appropriate use of shielding pump delivery. Generally suitable for shielding the pump medium viscosity range of 0.1 ~ 20cP. ② shielding efficiency of the pump is usually lower than a sealed centrifugal pumps. However, the low-power case, as compared with the double-seal pumps, the latter due to the increase of the cooling and flushing the system power consumption, so little difference in overall efficiency. ③ pump run-time, required flow rate should be higher than the minimum continuous flow. Shielding pump This is especially important, because in a small flow of operating conditions, pump less efficient and would result in fever, so that evaporation caused by fluid transfer pump dry, causing sliding bearing damage. 3. Magnetic drive pumps and canned pump comparison In the past decade, magnetic drive pumps have become the common areas of application equipment. In contrast, shielding pump prices has been seen as a higher and more specific pumps, in most cases there are special order only when the design and manufacture. Although this view with the standardization of the emergence of shielding pumps are changing, but the shield pump in the market is still only a relatively small share. In general, the reliability of non-seal pumps equal to or better than equivalent sealed pumps. But this will be a result of improper use of the two pumps (especially dry transfer, and deviate from the design point operation) easily understood damaged. Transmission medium with the non-lubricated bearings are sealed pumps dry in the long transfer will occur after the bearing wear. In the absence of running monitor the situation closely, this wear is invisible, in some cases, may lead to pump damage and sealed sets of rupture. The standard magnetic drive device in case of damage will make the liquid spilled into the coupling body, and released into the outside world through the coupling bearing the atmosphere. This leakage is usually due to fluid flow through the tortuous path to be modest, generally does not cause serious consequences. The standard magnetic drive can also be a great improvement in order to avoid leakage, improved method is used to prevent the coupling mouth ventilation pressure on the body and the adoption of auxiliary (drive) shaft seal to prevent leakage. In contrast, shielding pump will leak fluid sealing the motor body, and prevent further leakage. However, liquid seal should live only in the close attention of Pressure Vessels (motor shell) to the junction box between the cable connector where possible. This site has always been the only weakness of the pump shield. Poorly designed, will second (referring to the motor shell) sealing can not afford to no effect. Even if the sealed package if damaged, magnetic drive pumps can be completely cleared, and the undamaged parts can be reused. If necessary, such repairs can be carried out in the field. The leak to the shield pump motor windings will damage the body's fluids. While some pump has a removable stator structure, but most of the canned motor pump are based on the sealed motor or have welded structure, which requires to be repaired or re-sent to the factory to replace an expensive body parts. For standard magnetic drive pump, do not need to approve the use of dangerous areas, while the shield pump requires certification. In many cases, such a certificate in European countries are also inconsistent with each other, it may require an additional operating conditions monitoring devices, such as the need to ensure that the process liquid stored in liquid level detector. For the standard form of shield pump, the temperature limit at about 100 ℃ or less. Determining factor is used in motor winding insulation grade, in order to overcome this problem, motor with separate cooling circuit, thereby increasing the pipeline, cooling fluid source, the additional cost of pumps and heat exchangers. The standard synchronous magnetic drive pumps can operate at about 400 ℃ temperature. In general, magnetic drive pumps to meet the non-seal pumps 90% of all applications. Complete technical specifications of this pump, the price of economic, delivery time is short, easy to use, maintenance electrician is not required to participate, but also with the ordinary sealed pump a direct swap. PUMP structurally complex and expensive, often can not meet the normal standards. In addition, the sealing component involves the maintenance issues, many types of installation problems, as well as long delivery times, etc., all of which makes the shielding used in magnetic drive pumps can only pump can not be met, the various edges of high-risk applications. Kenji easy to see that these two pumps while at the same time market share, but the magnetic force driving pump will occupy a larger market share, and to become tomorrow's environmental, safety equipment, the main industries. In China, due to people's environmental awareness is not yet strong enough sound environmental regulations, coupled with enforcement is not enough, people pump leakage is a common problem due attention. So that domestic pump manufacturers on how to minimize the pump (especially for industrial use pump) Leakage of very low cost. Result of domestic non-seal pumps (including magnetic drive pumps and canned pump) of the research, development level and the international advanced level compared to the fairly far behind. With China's accession to WTO, as well as the past five years, the environmental protection industry's strategic priority to the development approach proposed, can be expected to vigorously develop the non-seal pumps, will be the future of China's industrial pumps used in a trend.


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