extraction check valve

I. Introduction:

CKH643H extraction check valves are used in extraction systems of power plants or cogeneration plants, or in pipelines of other systems carrying non-corrosive media such as water. They prevent accidents where the pressure inside the steam turbine suddenly drops during partial load operation, causing steam in the extraction pipes and various heaters to flow back into the steam turbine, which may damage the turbine blades and destroy the steam turbine generator. They also prevent water leakage from the heater system pipes, ensuring that when the water level in the feedwater heater exceeds the limit, the pneumatic device components receive the liquid backflow signal and quickly isolate the steam turbine, providing maximum protection for the steam turbine or extraction system.

II. Performance Requirements:

1. The CKH643H extraction check valve adopts a structural type combining an independent check valve and an auxiliary pneumatic closing device. When the steam turbine starts operating, the air source in the control system enters the lower chamber of the auxiliary closing cylinder through the electromagnetic directional valve, pushing the piston of the auxiliary closing cylinder upward to compress the spring for energy storage, and the valve disc opens under the push of the pipeline medium. When the system fails, the pipeline medium pressure drops, and the valve disc closes under its own gravity. At this time, the electromagnetic directional valve of the control system receives the signal, and the air source reverses, causing gas to enter the upper chamber of the auxiliary closing cylinder, which together with the spring pushes the cylinder piston downward to help the valve disc close at the fastest speed. After the valve disc closes, the valve obtains a certain locking force from the auxiliary power device to prevent steam and condensed water in the pipeline system from flowing back, protecting main equipment such as the steam turbine.

2. The valve actuator adopts a pneumatic-open type. Once the electromagnetic directional valve receives the signal and the air source reverses, the actuator spring and the air source of the electromagnetic directional valve can quickly close the valve, with a closing time of 0.5 to 1 second.

3. The installation of the auxiliary power device does not affect the reliability of the valve. In case of a fault in the auxiliary power device, the valve can still close automatically under the action of the valve disc and its own weight and reverse airflow.

4. The valve is equipped with open and close position switches, which can be remotely transmitted to the central control room for operators to timely understand the valve status. It is also equipped with a local mechanical valve position indicator.

5. The valve actuator is in the closed state when power, gas, or signal is cut off.

6. The control box is equipped with local and remote control. When local control is selected, operating the valve open and close buttons can control the valve opening and closing, or when a fault signal is received, the buzzer alarm sounds and the valve closes. After the system fault returns to normal, the valve needs to be manually operated to open and close. When remote control is selected, if the valve needs to be opened or closed, the valve will automatically open or close after the control box receives the opening/closing signal or fault signal, without manual operation.

7. Scope of supply: Each valve is equipped with an actuator, a manual test ball valve, a three-piece air source treatment unit, a solenoid valve, a limit switch, and a local operation control box.

III. Installation and Maintenance:
1. Before installation, clean the dirt and dust inside the valve to ensure the use effect.
2. The installation direction of this valve shall be consistent with the medium flow direction and the arrow on the valve body. The flange size shall comply with the JB/T79-94 standard.
3. When conducting a strength test on the pipeline, the valve shall be opened.
4. The products of our factory have passed strict tests before leaving the factory. Please do not arbitrarily tighten the components of each part of the product.
5. If the valve is stored for a long time, it shall be kept in a dry warehouse, and rust prevention work shall be done regularly.

IV. Technical Parameters: