extraction check valve

I. Introduction:

       The CKH643H extraction check valve is used in the extraction steam systems of power plants or cogeneration plants, or in pipelines of other systems transporting non-corrosive media such as water. It prevents accidents where, when the turbine is under partial load, the internal pressure of the turbine drops suddenly, causing steam in the extraction pipes and various heaters to flow back into the turbine, which may damage the turbine blades and destroy the turbo-generator. It also prevents water from leaking from the heater system pipes and entering through the tightly closed extraction steam, ensuring that when the feed water heater experiences an ultra-high water level, the pneumatic device components receive the liquid backflow signal to quickly isolate the turbine, providing maximum protection for the turbine or the extraction steam 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 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 to move upward and compressing the spring to store energy. 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. Together with the spring, it pushes the cylinder piston to move downward, helping the valve disc close at the fastest speed. After the valve disc closes, the valve obtains a certain locking force on the valve disc from the auxiliary power device to prevent steam and condensed water in the pipeline system from flowing back, protecting main equipment such as the 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 failure of the auxiliary power device, the valve can still close by itself under the action of the valve disc, its own gravity, 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 remains in the closed state when power, gas, or signals are 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's 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 performing the strength test on the pipeline, the valve shall be opened.
4. The products from our factory have passed strict tests before leaving the factory. Please do not randomly tighten the components of each part of the product.
5. If the valve is stored for a long time, it should be kept in a dry warehouse, and rust prevention work should be done regularly.

IV. Technical Parameters: