Views: 212 Author: Site Editor Publish Time: 2021-08-15 Origin: Site
The pressure ultra-high temperature hydraulic control globe valve is the key equipment installed in the hypersonic (M>10) wind tunnel test device. The maximum working pressure of the valve is 12MPa. Its nominal diameter is DN500. The maximum working temperature is 900℃, and the medium is high-temperature dry air. It can work with brass gas fittings or brass propane fittings.
According to the working conditions and system requirements, when the valve leaves the factory, in addition to the strength, high-pressure sealing, and low-pressure sealing tests according to the API598 standard, the heat insulation test and the matching test of the hydraulic cylinder of the actuator and the working pressure and temperature of the medium are also carried out. Only then can it be used with industrial hose fittings or high pressure hydraulic fittings.
The requirement for the shell insulation test is that when the medium temperature is 900°C, the outer surface temperature of the shell is ≤80°C. According to the requirement of matching between the hydraulic cylinder and the medium parameters, the medium pressure is 7 grades: 1MPa, 2MPa, 4MPa, 6MPa, 8MPa, 10MPa and 12MPa. The temperature of the medium is 505°C, 611°C, 715°C, 809°C and 900°C in 5 levels.
The medium pressure is proportional to the cylinder pressure, which is easy to calculate. However, the temperature of the medium will affect the hardness of the seal pair (STL) and the specific pressure of the seal pair. This data cannot be found in the valve design calculation manual and related documents. Therefore, only through experiments can we determine the matching relationship between the cylinder pressure and these media parameters.
The pressure of the oil cylinder must overcome the force of the medium, the necessary sealing force of the sealing pair and the friction between the valve stem and the packing. If the pressure of the oil cylinder is too high, the sealing surface will be crushed and the service life of the valve will be affected. If the pressure of the oil cylinder is too low, the sealing pair cannot be sealed and the valve cannot work normally. Therefore, it is very important to select and adjust the oil cylinder pressure correctly to achieve a reasonable match. Therefore, we need to use the oil pressure gauge tester and digital pressure switch to help us debug.
The first is the heat insulation effect test of the shell. Between the inner cavity of the valve and the inner wall of the valve, there is a 100 mm thick thermal insulation layer. The thermal insulation layer is mainly made of two materials. The innermost layer is 3-layer of thermal insulation sleeves. The thickness of these three layers are 8 mm, 2mm and 1mm respectively. Each layer is drilled with vent holes with different diameters, and the total vent hole area is about 0.03%. The largest hole is φ10 mm and the smallest hole is φ3 mm.
The metal sleeve is wrapped with stainless steel wire mesh, and the mesh is wrapped with 3 layers of silica gel aluminum fiber cloth, and the cloth is wrapped with 3 layers of aluminum silicate fiber felt. Even the gaps on the outside of the felt are tightly packed with aluminum silicate fiber cotton. This not only ensures that the insulation layer is ventilated, but also ensures that the filaments will not be drawn away by the airflow. In the heat insulation test, a resistance wire heater is placed in the cavity of the valve body, and the insertion temperature rises to 900°C. After another hour, if the surface temperature of the valve body does not exceed 75°C, the test result is qualified.
The development and testing of high-pressure and ultra-high-temperature hydraulically controlled globe valves is a complex system project. It has outstanding innovations in structure, material selection, heat insulation, cooling system, hydraulic automatic control system and NV4500 hydraulics, providing users with reliable operation basis.
In addition, in the case of high temperature and high pressure, stainless steel hydraulic adapters and stainless steel hydraulic hose crimp fittings are more ideal options.
