For thermal oil conditions required three-way control valve should bear a high temperature, around 350-degree centigrade, so it makes a more different design than other 3-way globe valves.
Three-Way Control Valves for Thermal/Heat Oil
Three-way control valves are designed with three flow ports, AB, A and B port. This type of control valve not only modulates flow capacity, but also can be diverting flow to two outlet ports, or mixing two inlets to one outlet port with different temperatures or pressures.
Difference Design of Three-Way Control Valve for Hot Oil
- Bonnet design. THINKTANK uses stainless steel bellows bonnet and flexible graphite packing as double sealing to protect the actuator performance, and also effectively isolate the medium in the pipeline from the outside, greatly improving the safety and reliability of the product seal.
This 3-way control valve was specially developed for the oil furnace temperature control system of the heat setting machine in the textile machinery industry.
- It usually assembles a pneumatic or electric actuator with a 4~20mA input signal or on/off control signal to change the valve opening, at the same time, the isolation signal of the valve opening will feedback to the control system.
- The thermal oil 3-way control valves are generally flowing to open, so its stability is better than others.
- The servo amplifier adopts deep dynamic negative feedback to improve adjustment accuracy.
- The electric/pneumatic three-way control valve used for heat-conducting oil saves automation investment. Compared with single-seat, double-seat, or sleeve/cage type globe control valves, the same system can save one unit valve, simplify the system and save cost for the end-users.
- There are many types of electric operators, which can be applied to 4~20mA or 0~10mA DC or 1 ~5V DC, 0 ~10V DC, with power supply 380V AC, 220V AC, 24 V DC, or just simply air supply 2 ~ 6 bars.
- If using an electronic actuator to control the valve opening by the current signal, no need servo amplifier.
- The bellows seal type bonnet will be a complete seal to the moving stem, preventing any fluid leakage.
- The hot-oil 3-way control valve is not only guided by the bushing at the valve bonnet but also guided by the side of the valve plug and the inner surface of the valve seat, with a large guiding area and reliable operation.
Case Study of Heat Oil Application(Motorized 3-Way Control Valve)
This fluid solution is for an Indian customer on a heat oil project. There is no control equipment such as a controller on-site, so we provide the integral solution according to the customer’s parameters.
- Flow volume approx.: 120 m³/h
- Pressure head, approx.: 45 m l. c.
- Medium: Therminol 66
- Operation temperature: 280 °C
- Max. admissible operating temperature: 335 °C
- Control valve with the actuator in 3-way execution with flanges and bellow sealing
- Nominal size: DN125
- Nominal pressure: PN16
- Valve function: Distribution function
- Actuator: Electric actuator prefer (ARI)
Solution & Valve Principle
The thermal oil enters the equipment through the three-way control valve, and the temperature sensor collects the process variables on the equipment and delivers parameters to the controller, after comparing the process variable with the setpoint, the controller sends a corrective signal to the three-way control valve, in case modulating the valve opening to reach the required value.
When the temperature of the thermal oil in the equipment is lower than the setpoint, the controller sends an analog signal to increase the opening in the left → right horizontal channel of the 3-way control valve.
Conversely, when the temperature of the thermal oil is higher than the setpoint, the controller sends a signal to let the three-way control valve left → right channel opening decrease, while the left to the bottom channel opening increases, allowing the medium (thermal oil) to circulate back to the flow.