Valve common problem analysis low carbon energy saving valve product technology introduction

Valve common problem analysis low carbon energy saving valve product technology introduction

The cut-off valve should be hard sealed as far as possible
The lower the leakage requirement of the cut-off valve, the better the leakage of the soft seal valve is the lowest, the cut-off effect is of course good, but not wear-resistant, poor reliability. From the leakage and small, sealing and reliable double standard, soft seal cut off is better than hard seal cut off. Such as full-function ultra-light regulating valve, sealed and stacked with wear-resistant alloy protection, high reliability, leakage rate of 10-7, has been able to meet the requirements of the cut-off valve.
Double seal valve can not be used as a cut-off valve
The advantage of the two-seat valve spool is that the force balance structure allows the pressure difference to be large, while its outstanding disadvantage is that the two sealing surfaces can not be in good contact at the same time, resulting in large leakage. If it is artificially and forcibly used to cut off the occasion, obviously the effect is not good, even if it has made many improvements (such as double seal sleeve valve), it is not desirable.
The two-seat valve is easy to oscillate when working with small opening
For a single core, when the medium is flow open type, the valve stability is good; When the medium is flow closed, the stability of the valve is poor. The double seat valve has two spool, the lower spool is in the flow closed, the upper spool is in the flow open, so, in the small opening work, the flow closed type spool is easy to cause the vibration of the valve, this is the reason why the double seat valve can not be used for the small opening work.
The anti – blocking performance of the straight stroke valve is poor, and the anti – blocking performance of the Angle stroke valve is good
Straight stroke valve spool is vertical throttling, and the medium is horizontal flow into and out of the valve chamber flow channel must turn back, so that the valve flow path becomes quite complex (shape such as inverted S-type). In this way, there are many dead zones, which provide space for the precipitation of the medium, and in the long run, cause blockage. The direction of the Angle stroke valve throttling is the horizontal direction, the medium flows in and out horizontally, and it is easy to take away the unclean medium. At the same time, the flow path is simple, and the medium precipitation space is very little, so the Angle stroke valve has good blocking performance.
Why the straight stroke control valve stem is thinner?
It involves a simple mechanical principle: large sliding friction and small rolling friction. Straight stroke valve stem up and down movement, packing slightly pressed a little, it will put the valve stem wrapped very tight, produce a large back difference. For this reason, the valve stem is designed to be very small, and the packing is commonly used with a small coefficient of friction PTFE packing, in order to reduce the backdifference, but the problem is that the valve stem is thin, easy to bend, and the packing life is short. To solve this problem, the best way is to use the travel valve stem, that is, the Angle stroke of the valve stem, its valve stem is 2 ~ 3 times thicker than the straight stroke of the valve stem, and the choice of long-life graphite packing, stem stiffness is good, packing life is long, the friction torque is small, small return difference.
The pressure difference of Angle stroke type valve is larger
Angular stroke type valve cut off pressure difference is large, because the medium in the spool or valve plate resultant force on the rotation shaft torque is very small, therefore, it can withstand a large pressure difference.
Socket valves instead of single – and two-seat valves did not work
The sleeve valve, which came out in the 1960s, was widely used at home and abroad in the 1970s. In the petrochemical plant introduced in the 1980s, the sleeve valve accounted for a larger ratio. At that time, many people believed that the sleeve valve could replace the single and double seat valve and become the second generation of products. Today, this is not the case, single seat valve, double seat valve, sleeve valve are used equally. This is because the sleeve valve only improves the throttling form, stability and maintenance better than the single seat valve, but its weight, blocking and leakage indicators are consistent with the single and double seat valve, how can it replace the single and double seat valve? So, it has to be shared.
Desalting water medium using rubber lined butterfly valve, fluorine lined diaphragm valve short service life
Desalting water medium contains low concentration of acid or alkali, they have a greater corrosion to rubber. The corrosion of rubber is characterized by expansion, aging and low strength. The use effect of butterfly valve and diaphragm valve lined with rubber is poor. The essence is that rubber is not corrosion resistant. After the rubber lining diaphragm valve is improved to the corrosion resistance of fluorine lined diaphragm valve, but the diaphragm of fluorine lined diaphragm valve can not stand up and down folding and broken, resulting in mechanical damage, the life of the valve is shorter. Now the best way is to use water treatment ball valve, it can be used for 5 to 8 years.
Pneumatic valve piston actuator use will be more and more
For pneumatic valve, the piston actuator can make full use of the air source pressure, the size of the actuator is smaller than the film, the thrust is greater, the O-ring in the piston is more reliable than the film, so it will be used more and more.
Selection is more important than calculation
Calculation and selection compared, selection is much more important, much more complex. Because the calculation is only a simple formula calculation, its itself does not depend on the degree of the formula, but depends on the accuracy of the given process parameters. The selection involves more content, a little careless, will lead to improper selection, not only cause the waste of manpower, material resources, financial resources, and the use of the effect is not ideal, bring a number of use problems, such as reliability, life, operation quality, etc.
On the afternoon of September 1, in the “2010 Shanghai (Second) Water Industry Hot Forum” hosted by China Water Network, Shanghai Municipal Engineering Design and Research Institute, urban sewage, Shanghai Municipal Drainage Co., LTD., and China Association for Science and Technology, Zhengzhou Zheng Butterfly valve Co., LTD. Senior engineer Zhao Guoxi introduced several low carbon energy saving product technology.

Zhao Guoxi introduced three new types of valves, namely eccentric half ball valve, oblique seat hard seal slow closing check valve and full pressure high speed exhaust valve.

The eccentric hemisphere valve body adopts the ball structure, the rigidity is good, the strength is high; The valve disc adopts hemispherical structure, the valve shaft adopts semi-axial structure, and the valve disc rotates 90° when fully closed and fully opened. In the fully open state, the valve disc all enters the body cavity, so that the inner chamber of the valve is all unblocked. Valve body and valve disc sealing surface, using hard alloy surfacing technology, high hardness, high wear resistance, can cut off the medium metal or braid sundries; It can resist scouring of slurry or granular flow medium. It can automatically remove dirt from sealing surface. Valve disc adopts large eccentricity structure, sealing surface frictionless open and close, flexible switch, long service life. The valve shaft seal is made of flexible graphite ring or O-ring. The shaft seal can be replaced and adjusted without removing the driving device.

Inclined seat hard seal slow closing check valve seat is inclined, the valve opening and closing stroke is short, opening and closing performance is good. Butterfly plate is double bias structure, the valve opening and closing movement is reasonable. Stainless steel metal hard seal pair, long service life, maintenance free replacement. The valve chamber structure elements have good flow characteristics, small flow resistance and energy saving. Quick and slow closing, can effectively prevent water hammer. Butterfly plate/valve shaft open and close flexible, no stuck.

Have pressure water supply pipe exhaust problem, is decades worldwide technical problems, because of the pressure water pipe exhaust impurities, gas water two phase flow and stable operation, water hammer in pipeline cutoff bridge, its pressure often up to 200 ~ 400 m water column, some engineering calculation, even nearly kilometers, enough to cause any * * degrees of water supply pipe damage. In fact, the large water transmission projects and urban water supply pipe accidents are many. According to relevant data, China’s major cities such as Beijing, Shanghai, Hong Kong and other water supply pipe network annual pipe burst about 2000 times, the general provincial capital city annual pipe burst about 1000 times, the main reason on the water is the exhaust is not free. The purpose of the research on the full pressure high speed exhaust valve is to solve the problem of the air exhaust of the pressure water supply pipeline is not clean and unstable, and to reduce or completely eliminate the stubborn disease of the urban water supply pipeline pipe burst.

Full pressure high speed exhaust valve can be in pressure pipeline water and gas phase under the same flow state, does not produce “air support”, can be continuous high speed exhaust exhaust valve; No need for manual auxiliary exhaust, can be high-speed discharge of any complex pipe gas truly automatic exhaust valve; It has the buffering function in line with the requirements of the water hammer protection theory, and has a good effect in preventing the start of the pump water hammer, stopping the pump water hammer and eliminating the damage of pipeline pressure oscillation; The exhaust seal is advanced and reasonable, which overcomes the performance defect of ordinary exhaust valve which often runs a lot of water.