The analysis of heavy hammer-type butterfly valve applications
Technical Principles
Hammer-type butterfly valve is composed by valve body, hydraulic linkage bypass valve, heavy hammer, released device, manual oil pump (or electric oil pump), fuel tank rack transmission and electronic control components (see Figure 1). By the oil pump pressure oil input rack drive cylinder, through piston rack gear to promote butterfly plate main axis rotation to open the butterfly plate, and moves coaxial heavy hammer to the highest point. Heavy hammer pawl through releasing device lock spindle lock spindles; the fix of lock spindle axis is controlled by the electromagnet and support devices. When the accident occurrs, due to electronically controlled part operation, electromagnet power off, spindle lock out of control, under the heavy hammer seld-weight effect, with the action of tripping around the axis, so the butterfly valve will be self-closed.
Figure 1 Principle indication of heavy hammer-type butterfly valve movements
The butterfly valve hydraulic system, using two-section throttle to control the butterfly valve closing speed, when it starts, the speed is faster, to reduce the speed time and the rate continued to rise; the later stage of closing slowly to control the water pressure increasing rate. Hydraulic control principles are shown in Figure 2.
Figure 2 D741X-10 heavy hammer-type butterfly valve hydraulic control principles indications
2、Technical characteristics and main technical parameters
2.1 Technical Features
With complete machine assembly manual-electric dual-purpose oil pressure system, makes the complete machine structure is compact, easy to operate.
In the absence of external power supply situation, it can take advantage of gravity storage to shutdown itself. When the machine is too fast, the bearings overheating and loss of field generator can automatically shut down, thus to automatic protect the machine sets.
With fast or slow two-section shut-down features.
Using Solenoid-controlled lock mechanism, not only is safe and reliable, but also the operating power is small.
2.2 Main technical parameters, indicators
Using D741-10-type heavy hammer-type butterfly valve as an example, the main technical data are: pressure, 1MPa; diameter, φ400, φ500, φ600, φ800, φ1000, φ1200; the maximum used water head, 100m; the highest step-up water head, 145m; opening time, manual almost 5min, the electric almost 1min; closing time, fast-off section 5 ~ 10s; slow closed section:10 ~ 50s; overspeed protecting scope, 1.8 times of the rated speed (adjustable).
3、Conclusion
First of all, to improve the reliability of equipment operation and ensure safe shutdown. Second, to reduce the labor intensity of workers, reducing the maintenance workload. Two machine units reduce 4 workers on duty, with annual savings of about 80,000 yuan.
In addition, the valve in the absence of nobody (a few workers) on dutyof net power plants or isolated power station, when they lose their power, can trip automatically from the heavy hammer and shut down, without backup DC operating power.
In some power plant design, if under the conditions of the scheduled unit GD2 and hydraulic structures layout,you can not find a suitable guide vane closing time to ensure the unit rate on the appreciation and the appreciation of the water pressure does not exceed the standard required allowable value, at this time can take heavy hammer-type butterfly valve fast and slow two-section to close, first fast, using the power to reduce the rotary speed increased, then slow to reduce the water pressure increased. This method is reliable, compared to install artificial resistance and is economic compared to set surge tank.
