qinhuangdao zhongqing metallurgical valve co., ltd-ag尊龙凯时

industry news
on the gray dust unloading valve valve wear applications

large blast furnace gas dry dust removal system, water-saving, environmental protection and energy conservation, and other prominent advantages, has been used in a growing number of blast furnaces. gas dry dedusting system includes filtration systems, cleaning systems, temperature control system, ash and dust, and gas delivery system pressure control system. in general, each specific system processes steel enterprises above process some differences. for example, some steel companies dry dust removal system, eliminating the middle ash silo, warehouse and baghouse ash gray piping, in the middle of the connection pipe to install a manual valve, cinder valve (pneumatic valve) and a manual valve .

in this system, the process of internal general cinder operation, we need to open a valve known as cinder valve. these valves open frequently, the medium is extremely abrasive compressed gases and dust, so that life is short, the failure rate is high. cinder valve life of a business is only about three months, the main fault is that body piercing, and the sphere of sealing damage. due to the high failure rate of ash discharge valves, many companies are constantly trying to use a variety of wear-resistant valves, in order to prolong life.

this article will use the valve in this position now be introduced one by one, to analyze their strengths and weaknesses, in order to improve the cinder valve life to contribute.

first, the dome valve

clyde dome valve is a pneumatic conveying the companys patented products. its biggest feature is that you can have a hollow inflatable seal. when the valve is opened, seals discouraged, the ball out of contact with the valve, followed by rotating the ball valve to achieve open; in this process, non-contact seals and ball wear. when the valve is closed, inflatable seals, in close contact with the ball, to achieve sealing.
advantages there are three main dome valve. first, on the part of the inflatable seal may wear the sphere of realization of compensation, to achieve long life. second, due to the ring after a leak was unable to keep up the pressure and wear ring cavity, seal wear can be obtained by detecting changes in the status of seal chamber pressure. third, flexible expandable seal retraction material particles can be avoided due to the pressure difference material particles sliding on the seat and seal wear.

the main disadvantage of the dome valve has two points. first impatience wear. in an instant seal deflated, the pressure differential across the valve so that the dust-laden gas rapidly through the narrow space seal and sphere, dusty gas sphere and ring wear. although the seals are made of wear-resistant rubber, but wear rubber low hardness, wear resistant to dust, which can easily be milled pores and lead to seal failure caused by leakage. the second is not used in high temperature conditions. hollow rubber ring high temperature performance is poor, for medium temperatures exceed 100 degrees celsius conditions, such as power plants out of the economizer ash, dome valve can not be used.

second, wear ball

ball wear dry dust in the gas station on cinder common valve. its structure and general ball valve is insignificant, there are two kinds of fixed and floating. it is the main difference between ordinary ball that material. the ball valve and seat wear of the main material is wear-resistant metal or wear-resistant surface treatment, chrome or hvof tungsten carbide.
wear simple valve structure, easy to manufacture, mature technology, lower prices. manufacturers can produce a lot of choices for buyers is large.

shortcomings there are three main valve wear. first, because of wear-resistant metal or wear-resistant coating hardness and hardness than dust, or worse, at the same time limited capacity surface treatment technology surface hardened layer thinner, resulting in poor abrasion wear ball; frequently open the cinder stations, life is short. gas dry dedusting system cinder station, ordinary wear life of ball only three months, six months or so long. second, the valve opening and closing process, the ball and seal the auxiliary contact a long time, so that the ball and seal pair have some friction, thereby accelerating the wear of the ball and seal failure. third, the existence of a gap between the ball and the valve body. many manufacturers of valve wear due to lack of processing technology and process design, often causing these tiny particles into the voids inside, resulting in catching the ball rotation, not even close place.

third, wear half ball

wear wear ball half ball is developed on the basis of. its main structure is characterized by an axis with the axis of sealing sphere there is a certain deviation, so that the valve opening and closing process can shorten the time of sealing contact with the ball, reducing both wear.

basically the same half-ball wear and abrasion resistant material selected ball. compared to wear ball, wear half ball switch act quickly to further enhance the wear resistance. eccentric structure between ball and seat, allowing the ball to be able to automatically compensate for wear, while the ball valve can be more rapidly approaching or departing at the opening and closing, reducing the contact time between the ball and seat reduces wear. but for frequent switching of cinder stations, life is still not ideal. the key reason is that the material properties, can not long withstand the impact of fly ash friction. another point, and wear the same ball, there is a gap between the ball and the body, although the half-ball half the size of the void space. valve in the closing process, the gap may enter dirt, so the ball can not rotate in place. in fact, half ball, why the failure occurred in the cinder system failures mostly related to this gap. after the gap into the dust, the ball rotation is not in place, there is a slight space between the seal pair, in the presence of a pressure difference at both ends of the valve case, this tiny space quickly through the dusty gas. dusty gas through the rapid wear of the ball and seat, and some even resulting in the sphere of the notches, valve perforation.

fourth, the ceramic ball

basically the same structure and wear resistant ceramic ball ball. the key difference between the two is the material. ceramic ball valve and sealing ring of structural ceramics, after the main components of alumina and zirconia material was purified by grouting or isostatic pressing sintered at high temperature. structural ceramics high hardness, to hrc88, and to overcome the shortcomings of conventional ceramics brittleness, good mechanical properties, wear resistance far more than wear-resistant metal. but the effect of the ceramic ball in cinder station for use on relatively poor, major fault is the sphere fragmentation. after the disintegration of the analysis, the fragmentation of the sphere and the reason is that the gap between the valve ball into the dust into the dust gathering in the gap to a certain extent, it will hinder the sphere of the rotation, the formation of reverse torque. hollow ceramic spheres shear poor performance, easily broken.

five ceramic half ball

the basic structure of the ceramic semi-ball half ball and wear similar. the main difference is that the ball cap ceramic half ball hemisphere is structural ceramics, structural ceramics seat. ceramic half ball only inherits the advantages of semi-valve structure on the wear, but also has the wear characteristics of ceramic materials, while avoiding the ceramic body resistant to global shear defects. in practical application process, the ceramic ball half showed a good trouble-free life time. however, it still has the ball itself inherent flaws, the gap between the ball and the body easily into the fine particles, hindering the rotation of the sphere, even allowing the ball to close the place.

sixth, ceramics gate valve

ceramic gate valve is a parallel double plate valve. a spring between the two valve plates, can automatically compensate for wear between the valve seat and the valve plate, but also so that the valve plate and seat remain in close contact to prevent dust from entering. valve plate and stem support specially designed to make the valve plate and down movement with self-rotating, so that the valve plate and seat can wear a uniform. sealing valve plate and seat adopt structural ceramics. ceramic gate valve widely used in the power plant ash pneumatic conveying system applications, the technology is mature, long life. however, in the blast furnace gas dry dust cinder conveyor systems, cinder valve on this station, using the results of ceramic gate valve is poor. the main fault performance in valve switch is not in place, generally two to three days will have this problem. after the disintegration of the discovery, the body cavity together a large volume of dust, dirt hinder the sliding valve plate. the reason why the gas dry dust cinder delivery systems and this failure does not occur in the thermal power plant ash pneumatic conveying systems, the fundamental reason for the thermal power plant system with ceramic gate valve is in a horizontal pipe vertically mounted, and blast furnace gas system which is horizontally mounted in a vertical pipe. valve opening and closing process, the dust fluid flow lines disorder, there will be some dust bypass valve plate into the body cavity. when horizontal pipe mounted vertically, dust due to gravity will fall, and will not accumulate in the body cavity; and when horizontally mounted in a vertical pipe, dust can not fall only going to gather in the body cavity.

in the blast furnace gas dry dust cinder conveying systems, cinder valve position of the harsh working conditions, frequent opening and closing, dusty gas valve wear resistance, abrasion resistance of the valve demanding. now available for all enterprises use diverse types of wear-resistant valves, each with its own advantages and disadvantages, from the practical effects of view, there is not a valve fully satisfy the requirements of the station.