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E:\WEB_LU\valvechina\web\industrial\trend\new_tech\main.asp
New Type
Pressure Self-balance Gate Valve
A FEED CONTROL
VALVE OPERATING WITHIN A WIDE
PRESSURE DROP RANGE
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The valve is intended
for controlling flow rate of liquids media at changing pressure within wide range. The
valve has a highly tight locking, a long overhaul period and is easy to repair. When
working under high pressure and flow rates, the valve design does not cause the failure of
the outlet connection and the pipe close to it. Unloaded bend system increases reliability
of the gland and sealing surfaces, the last enabling application of advanced materials
from metallic powders. Fields of application are various technological assemblies in heat
power stations (mainly, they are power supply assemblies), chemical plants and other
enterprises, where control of liquids flow rate is required under pressure differential
from 2 to 30 MPa (20 - 300 kgf/cm) and flow rate up to 700 tonnes/h. Conventional diameter
of the valve is up to 250 mm. The controlled medium temperature is up to 250 C. Control of
the valve within the whole range of pressure differential and flow rate is provided with a
single-turnover actuator with an electric drive of only 200 W (0.2 kW) power. The feed
control valve as compared to serially produced valves, enables controlling of water flow
rate at any load of the boiler unit, including starting and stoppage without by-pass
lines. The feed control valve successfully operates under the pressure drop of 20 MPa, is
controlled by the electric drive with power 22 times less than that in the conventional
valves, has a longer overhaul period and ensures operation of automatic systems within a
wide range of loading. The controlled medium is fed into the case (1), passes via the
holes, formed after alignment of the valve seat ports (2) and openings of the control gate
(3). Flow rate control is conducted by turning of the control gate interacting with a
spindle (4) and a pin (5) connected with it.
The profile of the
area formed on the gate's turning round its axis determines the flow rate characteristic.
The setting of the sealing surfaces provides the density of valve. Large clamping force
between the control gate and the seat at high-pressure differential is the main reason
limiting application of non-balanced type valves. To decrease the clamping force, in the
upper part of the valve considered there is a differential unloading device, consisting of
two interacting pistons, the upper and the lower. The active area of the lower piston is
connected with load pressure by means of a tube (6), that of the upper piston is connected
with the outlet manifold by means of the tube (7).
In the discharge
device a differential force is formed under the pressure differential effect, being
further supplied to the spindle connected with the control gate by the pin and through
thrust bearings (8) and (9), and the lever's bush (10), thus diminishing its clamping to
the seat.
The valve is
developed and manufactured on individual requests and all the equipment technological
parameters being accounted. The valves of the mentioned design have been successfully used
in many enterprises of Ex-USSR MINENERGO, in Voksberg and Tirbach heat power stations
(Germany) for 15 years. Installation of the valve in the feed line of only one boiler unit
eliminates application of two or three by-pass lines, six units of high pressure
accessories, labor expenses come lower for repair.กก
If you are interested
for using this design, you may contact by e-mail: allyqi@tcel.com
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