Performance requirements for coal chemical valve

(HY-industry technical centre)

Coal chemical valve performance requirements

  • First of all, from the conditions of working conditions, the coal chemical system for coal-to-liquid, oil-to-coal and coal gasification is in the medium (cinder) high hardness, high pressure and high temperature conditions. It is resistant to scuffing, anti-fouling, anti-crusting and quick cutting. The valve has a large caliber (generally DN300~DN450), frequent opening and closing and fast speed (30min action once, 5~10s/time), requiring good sealing performance and high reliability.

  • At present, the special wear-resistant ball valve has been widely used in the Texaco coal chemical industry and the coal-to-liquid industry. The medium coal water slurry contains 58% to 67% of coal powder solids. The black water system and the mortar system contain a large amount of extremely hard solid particles such as slurry, which are deposited, blocked or scaled in the valve chamber and are difficult to remove.

valve material

There are also great differences in the choice of valve materials for different temperatures:

  • Class 600 ~ 1500 normal temperature (-29 ~ 200 ° C) wear-resistant ball valve, the valve body material is ASTM A105 carbon steel forged ball valve, the ball is selected ASTM A182F304. For strong corrosive conditions, the valve body material can be austenitic stainless steel, duplex stainless steel, Inconel 625 ,Hastelloy C-276.

  • Class 2500 high temperature (300 ~ 510 ° C) wear-resistant ball valve body material is A182F22 or A182F347 stainless steel forged steel, the sphere is selected Inconel718. The stem is made of precipitation hardened stainless steel 17-4PH (Table 2) or A638-660.

  • Process technologyThe metal seal wear-resistant ball valve structure is suitable for transporting solid particles containing black water, slag water and coal water slurry. The ball and seat of the valve are supersonic spray (HVOF) JK117{(WC)/17Co} or valve seat stack. Welding stellite 12 (D812) cemented carbide, high-precision grinding of the ball and valve seat should be carried out by CNC grinding center during mass production. The valve stem has a metal and packing double seal structure that prevents solid particles from entering the stuffing box. The seat spring has a structure that prevents ash from clogging. The ball valve has the maximum working pressure on one side and the maximum pressure difference under the atmospheric pressure on the other side, completes the opening and closing and ensures a reliable seal. The leakage test of the hydraulic test should reach Class V of ANSI/FCI70-2.

How to choose coal chemical ball valve

  • Path: ANSI B16.34 standard.

  • Pressure level: The pressure level of the valve meets the order specification and process pipeline level requirements, and the valve body pressure level is not lower than the flange level.

  • Connection form: The ball valve process connection is flanged or butt welded. The flange standard is based on ANSI B16.5 and is connected by RF flange. The butt joint end standard is based on ANSI B16.25.

  • Structure length: The structural length of the valve is determined using the ANSI B16.10 standard.

  • Valve body and bonnet: Forgings ASTM A105, ASTM A182 F22, A182 F347 are used for heat treatment of valves requiring hydrogen sulfide prevention according to NACE requirements.

  • Sphere, valve seat: The ball is made of stainless steel 410SS, the surface is sprayed with high-temperature oxygen flame chromium carbide alloy (coating temperature 815 ° C), the hardness is above 64HRC, and the thickness is not less than 0.3mm. The seat is Inconel718 alloy, which is also hardened by spraying chrome carbide. Surface high-speed oxygen flame spraying chrome carbide alloy remelting treatment (temperature resistance 815 ° C), the coating wear resistance is not easy to fall off. The spherical surface hardness is 64HRC or more, and the thickness is not less than 0.3mm. The ball and the valve seat are manually paired and ground, and the seal inspection fully meets the API598 standard requirements. The sharp edge of the seat can self-scrape the ball from scratch, preventing the medium from entering the sealing surface of the ball and the valve seat, causing internal leakage and jamming.

  • Disc spring: The disc-shaped spring is used, and the material is In-conel718. The main function of the disc spring is to apply a pre-tightening force to the valve seat and the ball to ensure that the ball and the valve seat are tightly coupled. When the ball and the valve seat are displaced by thermal expansion, the ball can be effectively retracted to prevent the ball from collapsing with the valve seat. The chamfering of the rear seat cavity of the disc spring (angle calculated by fluid dynamics) makes it difficult for solid particles to accumulate behind the valve seat and affect the effective retreat of the valve seat.

  • Stem: The stem material is 17-4PH or A638-660. The valve stem is designed as a double seal with a shoulder-proof fly-out structure and a spring-loaded packing gland structure. The valve stem is provided with a double seal of metal sealed bearings and packing.

  • Filler: It consists of 3 compression molded combination pure graphite rings (Chesterton 5300) and 2 graphite anti-extrusion rings (Chesterton 1601) woven with Inconel alloy wire, which can withstand high temperatures of 970 °C. The packing gland has a preloaded disc spring, and the packing gland can continuously compress the packing without causing leakage.

  • Leakage rating: The valve flap and seat of the shut-off valve are in the form of a two-way seal with a metal seal. The metal sealed bearing is hardened and hand-paired for manual pressure design. The higher the pressure, the tighter the seal, which prevents solid particles from entering the stuffing box. The leak level meets the requirements of the API598 standard.

HY-industry is qualified superalloy supplier.We have more than 20 years experience in kind of  Cobalt alloy,Inconel, Monel,incoloy production.

Valve plant material supply business accounted for nearly 30%,Welcome the majority of valve enterprises to consult

When you want to know more about our products, please contact us:

http://hynickelalloy.com