High temperature, pressure tube digestion technology is widely used for alumina refining In the tube, turbulence of bauxite slurry flow allows for efficient heat transfer and short digestion time Hard to dissolve diasporic bauxite requires 9  pre-heating stages followed by 8 flashing stages before discharging in the dilution tank.Electric AngleType Needle Valves  are designed especially for Alumina Digestion Flash Tanks.

Valve operating conditions is the following :

Installation position: between flash tanks in pressure digestion Function:

Control fluid pressure and flow rate
T = 140ºC - 280ºC and P = PN4.0MPa  - 160MPa       


Process fluid: slurry, aluminate solution, Na2O 220 g/l   
 
erosive solid-liquid-gas 3-phase medium


Flow rate = 285 m3/h - 3503/h and Density = 1500kg/m3


Pressure drop: △P = 2.6 - 0.18MPa 


Control range:30 : 1 

Leakage:ANSI


Harsh operating conditions require valves to have special structural design of durable material and with good flow characteristics for accurate process control

Benefits


Structural improvements have doubled the lifetime and enhanced the control performance of  angle type needle valves for alumina digestion flash tanks.
Installation reduces

digestion's operating cost.


Valve lifetime doubled
Less maintenance cost of digestion piping due to longer lifetime of the valve
Less repair of throttle orifice and jet.


Down time caused by orifice failure, erosion and replacement are avoided after installation of the angle need valve.

Angle control valve can be disconnected from the whole allowing testing of disc and seat. In operation, seat and disc are visible and quick-wear parts can be easily replaced.


Specification

Valve Size : 2"-16"   DN50-DN400
Pressure :   Class 150-Class 900     PN1.6-PN16 
Valve body material :  WCB

Connection method: Flange