In the context of our company’s steam production process, a critical component is the temperature and pressure reducer, which lowers the steam from 2.48 MPa at 430°C to 0.35 MPa at 170°C to meet the requirements of other steam-consuming units. The system relies on two key valves: a pressure-reducing valve and a temperature-reducing water distribution valve, both of which are double-seat valves (model Y45/Y100-Dg150). These have been in operation for over four years and have generally met our needs. However, during this period, several issues have emerged that affect efficiency, control, and maintenance.
One major problem is the leakage of the pressure-reducing valve, especially when steam passes through the turbine. Despite being fully closed, the double-seat valve still allows significant steam leakage, leading to energy waste and increased operational costs. Another issue is the limited adjustment range of the valve. Under low-load conditions (steam flow below 10 T/h), the valve cannot regulate the steam pressure effectively, causing instability in the system. Additionally, the control accuracy and stability of the current setup are poor due to outdated electric actuators and a complex lever mechanism. This has led to manual operations and increased workload for operators.
Routine maintenance is also a challenge, with the system requiring 2–3 maintenance sessions per week. Since automation was not implemented initially, this has added to the difficulty of process management. To address these issues and improve safety and efficiency, we decided to upgrade both the pressure-reducing and temperature-reducing valves, along with their control systems.
The new valves must meet specific process conditions. For the steam pressure-reducing valve, the specifications include a DN150 size, steam temperature up to 430°C, and flow rates ranging from 4 T/h to 20 T/h. The inlet pressure is 2.45 MPa, and the outlet pressure should be maintained at 0.35 MPa. It must be equipped with an electric actuator operating on 220VAC/50Hz, with a 4–20 mA input signal and feedback. Similarly, the water reduction valve must handle a flow rate of up to 2500 kg/h at 108°C, with an inlet pressure of 0 MPa and an outlet pressure of 0.4 MPa, also with an electric actuator and 4–20 mA signals.
To select the right electric actuator, we evaluated three major manufacturers: KOSO (Japan), Auma (Germany), and Rotork (UK). After analyzing factors such as ambient temperature range, output torque, and reliability, we chose the Auma actuator. It offers a wide temperature range, sufficient torque capacity, and proven performance in similar environments. We also considered the availability of technical support and after-sales service, which are crucial for long-term operation.
For the control valve selection, we focused on manufacturers with strong reputations and reliable products. Fisher (USA), Neles (Finland), and Samson (Germany) were among the top contenders. Each provided detailed calculations and proposals based on our process parameters and the selected Auma actuator. After evaluating their models, delivery times, and cost-effectiveness, we finalized the selection to ensure optimal performance and ease of maintenance.
This transformation aims to enhance the reliability, efficiency, and safety of our steam system, while reducing energy consumption and operational costs.
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