The application of the triple eccentric butterfly valve in the petrochemical plant is on large-diameter pipelines. The cost of using the globe valve is very high and can not achieve zero leakage. In the case of emergency shut-off, a shut-off valve must be installed on the side of the globe valve. Although the V-type ball valve can also be cut off (zero leakage) and adjustment, but the cost is much higher than the triple eccentric butterfly valve. At present, the butterfly valve generally over DN300mm has gradually replaced the gate valve. Compared with the gate valve, the butterfly valve has the characteristics of short opening and closing time, small operating torque, small installation space and light weight. Butterfly valves are easy to combine with various driving devices and have good durability and reliability. Because of its remarkable advantages compared with globe valve, ball valve and gate valve, triple eccentric butterfly valve has been successfully applied in many occasions in petrochemical industry.
(1) The triple eccentric butterfly valve integrates adjustment and cut-off (to achieve zero leakage), and has been successfully applied in polyethylene equipment.
The reactor cooling water temperature control circuit of the polyethylene device is the most important part of the device. Whether the temperature control circuit can run smoothly or not directly determines whether the entire polyethylene device can operate safely and smoothly. The temperature-regulating water pipeline is a large-diameter pipeline (above dn450mm). Under normal working conditions, the triple eccentric butterfly valve is more stable and reliable than the ordinary control valve due to its high control ratio. When the interlock occurs, the triple eccentric butterfly valve can also play a shut-off role, and completely shut off (zero leakage). From the perspective of actual application, not only the investment cost is saved, but also the control is particularly stable.
(2) The coke cleaning valve at the outlet of the cracking furnace of the ethylene plant a valve with harsh conditions in the petrochemical industry. The carbon particles in the process medium may accumulate on the sealing surface of the valve, causing the sealing surface to bite and cause the valve to fail to open and close, and even shortening the service life of the valve. Compared with other types of valves, the triple eccentric butterfly valve is the most ideal choice because of its unique structural characteristics.
(3) For cut off and adjustment of the inlet pipeline of the gas turbine of the catalytic cracking unit of each refinery, due to the large diameter of the process pipeline, the process medium is high-temperature flue gas (up to 750 ℃), the triple eccentric butterfly valve is mainly used. Other such as the main fan inlet and outlet pipeline and vent valve, air compressor inlet and outlet pipeline, the torch vent valve, the slurry pump inlet and outlet, and the adjustment and disconnection of various high, medium and low pressure steam lines also use a large number of triple eccentric butterfly valves.Liquefied petroleum gas is very easy to leak. To meet the large circulation capacity and to avoid leakage, it is more reliable to use a triple eccentric butterfly valve on the main line of the storage tank import and export. In addition, the triple eccentric butterfly valve with steam jacket is selected for liquid sulfur to be transported in molten state in sulfur recovery unit.
