At present, the primary valves of gas drains all use gate valves. The opening and closing parts of this valve are gates. The movement direction of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully opened and fully closed. This valve has been in the normally open position for a long time since the gas generator was put into operation. Due to the large amount of impurities in the gas pipeline, the downcomer in the gas pipe drainer will accumulate more impurities after long-term operation. If the drain is withdrawn for cleaning, The primary valve must be closed reliably to ensure the safety of the operation, so the sealing performance of the primary valve is very important in the drain.
- The valve is easy to accumulate dust
The gate valve used on the drain is mainly a carbon steel gate valve. Its valve plate is a single plate. The valve's sealing is mainly to rely on external force to press the gate plate against the valve seat and seamlessly integrate with the groove surface of the valve seat. When the drainer is put into operation, the primary valve is in a long-term open state, and its sealing surface is exposed to the downcomer for a long time, reacting with impurities and other substances washed down in the gas pipeline, which can easily cause oxidation of the valve plate sealing surface, and at the same time redundant Impurities are deposited in the groove of the valve seat and cannot be cleaned in time. When opening and closing the gate valve, the valve plate cannot be tightly combined with the valve seat groove due to the serious dust accumulation in the valve seat groove. In the long run, the gate valve cannot be closed tightly and the drain cannot The normal exit also loses its due function. A new drain must be added to the pressurized opening next to the adjacent pipeline, which is costly.
- The gate valve is not easy to maintain
The maintenance of the gate valve is mainly to apply grease to the screw. However, because all the primary valves are installed at a higher position, it is difficult to maintain. At the same time, if the screw is greased, the valve screw is exposed to the air. If it is stained with dust, the gate valve is not easy to switch in place when it is opened next time. At the same time, the gate valve is manually operated when it is switched on and off. We cannot observe with the naked eye whether the inside has been switched in place, whether the sealing surface is tightly integrated with the valve seat groove, and can only be judged by the expansion and contraction of the valve stem.
- Unreasonable installation location and inconvenient operation
The gate valve is mainly used to cut off the source of the medium and play the role of opening and closing. It should be installed perpendicular to the flow direction of the medium. When applied to the drain, it is installed horizontally. Because the condensate in the pipeline flows up and down, this type of installation can only be selected, which determines the drawbacks of the valve. The valve plate will easily fall off if the valve plate is placed horizontally for a long time. The primary valve - gate valve cannot achieve the purpose of cutting off the source of the medium. At the same time, due to the large size of the gate valve, it needs to take up a large space when opening and closing. The route time is long, and it takes time and effort.
Reform scheme
According to the structural characteristics of the valve and mutual verification of theory and practice, the gate valve is replaced with a stainless steel ball valve and used in the gas pipe drain.
The ball valve evolved from the plug valve. It has the same opening and closing action, the difference is that the valve body is not a valve plate but a ball. When the sphere rotates 90°, it will show a spherical surface at the inlet and outlet, thus cutting off the flow. The ball valve is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. The advantages of using the stainless steel ball valve:
(1) Simple structure, light weight, convenient maintenance and corrosion resistance The same size DN100 stainless steel ball valve and gate valve are weighed 1/3 of the weight of the gate valve, which saves time and effort when installing and replacing the gate valve. At the same time, the composition of the stainless steel ball valve determines its corrosion resistance, and it can be fully opened and closed by turning the handle 90°when opening and closing, which is shorter than the gate valve and easy to operate.
(2) Dust is not easy to accumulate and dust removal is convenient. Because the sealing surface of the ball valve is in surface-to-surface contact, the sealing surface of the ball and the valve seat is isolated from the medium when it is fully opened or fully closed. When the medium passes, it will not cause the valve sealing surface to rust. At the same time, dust accumulation is not easy to form. Once ash deposits are formed in the downcomer, you only need to manually close the secondary valve, and the protective personnel wear a respirator to open the blocked part of the downcomer, and the dust is very thorough. It is easier to clean the dust than the gate valve. The valve plate of the gate valve is obstructed in the downcomer, and it is impossible to clean the dust straight up and down.
(3) The flow resistance is small. The sphere does not fall off and the safety factor is high. Among various valves, the flow resistance of the ball valve is the smallest. When the full-diameter ball valve is opened, the diameter of the ball passage, the valve body passage and the connecting pipe are equal and form one diameter, and the medium can flow through almost without loss. At the same time, the ball body of the stainless steel ball valve is tightly integrated with the valve seat, and it is not easy to fall off. When the drainer is put into and out of operation, it can safely and effectively block the gas.
Effectiveness verification
After replacing the gate valve with a stainless steel ball valve, the gate valve previously needed to be refueled and maintained every 1 to 2 months. Now the stainless steel ball valve does not need to be deliberately maintained. It only needs to open and close the valve several times in 3 to 6 months. Test whether the downcomer is blocked and whether the valve is flexible and easy to use. At the same time, since the replacement at the beginning of the year, there has been no failure of the valve switch due to dust accumulation.
After the "stainless steel ball valve" is applied to the gas pipe drain, it can judge the dust accumulation in the pipeline in a timely and accurate manner. It can guide the maintenance personnel to deal with the dust accumulation in the pipeline in time, and at the same time ensure that the drain can be tight during maintenance. There is a gas leakage accident to prevent safety accidents from happening.
The "stainless steel ball valve" has been applied to the gas pipe network system for nearly a year. According to the feedback from the maintenance personnel, there has been no dust accumulation on the valve so far, which ensures the normal and safe operation of the drain and has significant economic benefits.
