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Specific analysis of electric valves_Development and investment trends of domestic electric valves

First, the specific analysis of electric valves:
With the continuous development of science and technology, China's electric valve product market is also developing towards high-tech content, high parameters, strong corrosion resistance and high life. According to the analysis of electric valve technology at home and abroad and the analysis of the demand of electric valve market at home and abroad, the high-tech development trend and investment direction of industrial electric valve and electric valve industry in various industries in recent years are studied.
1. Valves for oil and gas wellhead devices
The valves for oil and gas wellheads are mainly single or double gates conforming to the US API6A standard, forged steel parallel gate valves with diversion holes or non-drainage holes, mud valves, angle throttle valves, and oilfield-specific parallel Regulating valve, oilfield-specific straight-through check valve, water injection, polymer-specific parallel gate valve, clamp-type parallel gate valve, pilot-operated safety valve and check valve.
2. Valves for oil and gas long-distance pipelines
The valves for oil and natural gas long-distance pipelines are mainly single or double gates complying with the US API6D standard, slab gate valves with diversion holes or non-drainage holes; forged steel or cast steel three-body, top-mounted or all-welded Fixed ball valve oil seal or pressure balanced plug valve; swing type or butterfly check valve, pass ball check valve; pigging valve.
3. Nuclear power valve
The electric valve for nuclear power has higher technical characteristics and requirements than the electric valve for conventional large-scale thermal power stations. Valves generally have gate valves, globe valves, check valves, butterfly valves, safety valves, main steam isolation valves, ball valves, diaphragm valves, pressure reducing valves and control valves; the highest technical parameters of representative electric valves are: maximum diameter DN1200mm (core 3 butterfly valve), DN800mm (core 2 primary steam isolation valve), DN350mm (core 1 primary circuit gate valve); maximum pressure: about 1500 pounds; maximum temperature: about 350 ° C; medium: coolant (borated water) and the like. Requirements for the production of nuclear-grade electric valve products: usually according to the nuclear industry standard EJ, the United States ASME, IEEE standards and French pressurized water reactor nuclear island machinery and equipment design and construction rules RCC-M.

Second: The specific types and parameters of the development of nuclear power valves are as follows:

(1) Gate valve without stuffing box: a Hydraulically actuated gate valve. The valve pushes the piston to open or close by means of its own pressure water. The nominal diameter of the valve: DN350, 400mm; working pressure: PN17.5MPa; working temperature: 315 °C. b fully enclosed electric gate valve. The valve should be equipped with a special screen-closed motor to open and close the shutter through an inner planetary reduction mechanism that is immersed in water. The valve has a nominal diameter: DN100~800mm; working pressure: PN2.5~45.0MPa; working temperature: 200~500°C. Note: The advantages of the above two non-filled gate valves: no packing seal, avoiding external leaks and reducing energy consumption. Disadvantages: complex structure and high cost.

(2) Nuclear power shut-off valve: Used for the shut-off valve on the auxiliary line. The valve is typically constructed in three configurations, a packed shut-off valve, a bellows shut-off valve, and a metal diaphragm stop valve. The valve medium is water and steam with medium parameters (medium temperature, medium pressure); nominal diameter: DN10~150mm.

(3) Butterfly valves for nuclear power: Butterfly valves used in systems for cooling systems and conveying air media in containment. The valve is usually of three types, namely a coaxial direct-connected rubber butterfly valve, an eccentric metal-sealed butterfly valve, and a double-acting type (the butterfly plate is separated from the sealing surface before turning, and the metal sealing butterfly valve is rotated). The valve nominal diameter: DN ≤ 2500mm; working pressure: PN <4.0MPa; working temperature: 100 ~ 150 ° C. In addition, for the quick closing butterfly valve in the air duct system, its nominal diameter: DN400~1200mm is also listed as the development direction. In addition, safety valves that meet seismic requirements are also urgently needed to develop nuclear electric valves.

Three: Marine oil valve

The oil production, blowout prevention, water injection, gas injection, underwater equipment and other systems of offshore oil production platforms need to develop some special electric valves that are resistant to seawater and salt spray erosion. These electric valves require strong anti-corrosion, anti-storm and other abnormal external forces, and require reliable sealing, flexible operation and convenient maintenance.

Four: petrochemical, power valve

Petrochemical and electric electric valve products, the focus of structural adjustment is the development of missing products. as follows:

(1) High-temperature and high-pressure regulating valve The high-temperature and high-pressure regulating valve used for large thermal power units should be determined according to its flow characteristics and working condition control requirements. It can be single seat or double seat or sleeve structure. The nominal diameter of the regulating valve: DN50~500mm; nominal pressure: ≤42.0MPa; use temperature: 510~570°C.

(2) High-temperature and high-pressure large-diameter safety valve The high-temperature and high-pressure large-diameter safety valve used in the steam system can be spring-loaded. The key problems solved in the design are: setting pressure, return pressure, sealing performance, repetitive motion stability and spring fatigue of this type of electric valve. Its nominal diameter: DN200~400mm; nominal pressure: ≤5.0MPa; maximum operating temperature: 570°C

Four: environmental protection valve
The electric valve that the environmental protection system needs to develop: ceramic sheet sealing rotary valve, PVC plastic valve, large sealing surface slab gate valve, stainless steel plug valve and so on.

V: Valves for metallurgical systems Valves for metallurgical systems, because the medium is often powdery and suspended solid particles, and the temperature is higher, so the requirements for wear resistance, temperature resistance and corrosion resistance of electric valves are higher.

The specific types and parameters of valve development for metallurgical systems are as follows:

(1) Discharge slab gate valve The “ash discharge slab gate valve” used in the ironmaking and ash removal system of steelworks. The medium of the ash removal system, "ash powder", not only has a shape of particles (sometimes a dispersed shape, sometimes a mixed shape), but also has a certain viscosity and is also sandwiched with carbon monoxide (CO). Due to the particles in the “ash powder” of the medium, the valve seat often has different degrees of damage, abrasion and wear. Therefore, the main parts of the “ash discharge slab gate valve”, such as the ram and the valve seat, are required to have Strong wear resistance. The working pressure of the iron and ash removal system is in the low pressure range of about 0.25 MPa; the temperature is in the range of ≤250 °C (normally, normal temperature, sometimes the instantaneous temperature can reach 250 °C); the nominal diameter is only from DN50mm~ DN400mm (DN300mm diameter is the most common).

The structure of the valve adopts a drainage hole with an "enlarged sealing surface", which not only improves its wear resistance, but also satisfies its sealing performance; and can prevent the ash powder from entering the bottom body of the valve body. In the design, the current slab gate valve with a diversion hole can be fully utilized, and the valve seat can be changed to the "enlarged sealing surface" sealing state. For wear resistance, the metal-to-metal hard seal has the longest life, but the metal-to-metal "enlarged sealing surface" is hard-sealed, and one standard allows leakage. (If the design is zero, the leakage cost will be very high. It is difficult to process); the second is not as good as non-metallic materials. The seal is not as good as the non-metallic material because the metal surface will produce an oxide when it is abraded. Although this layer of oxide covers the corroded part, it can slow down the further corrosion of the metal, but if it slips, the layer The oxide is removed, causing further corrosion of the exposed metal surface, which accelerates wear and impairs sealing performance. The use of non-metallic materials not only saves costs, reduces the difficulty of processing, but also guarantees its sealing performance.

Since the working temperature of the steelmaking and ash removal system of the steel mill is generally normal temperature, sometimes the maximum temperature is only 250 °C. Therefore, the use of non-metallic materials (parallel polystyrene is recommended) as a sealing surface, which can meet the temperature and wear resistance of its working conditions, and can also meet its sealing performance. Non-metallic materials - para-polyphenylene, suitable temperature ≤ 300 ° C, and harder than hard PTFE, can meet the working conditions of the ash removal system of the ironworks, is an ideal sealing surface material. The seat material is recommended to use 1Cr13.

(2) Stainless steel valve resistant to strong acid corrosion The metallurgical system uses a stainless steel valve resistant to strong acid corrosion. The nominal diameter of the valve: DN50 ~ 2400mm; nominal pressure 0.05 ~ 1.6MPa; maximum use temperature: 1050 ° C.

Six: alumina industrial valve In the production process of alumina industry, the medium is mostly alkaline mud and granular materials, the crusting phenomenon is extremely serious, and the erosion of the medium to the electric valve body cavity and internal parts is also very serious. Therefore, the valve for alumina industry requires anti-crust resistance and crusting; erosion resistance and erosion resistance.

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