Steam systems are said to be performing at optimum when productivity is high and product output is of superior quality with the lowest possible energy consumption. Precise control of process temperature and steam pressure plays a crucial role in this.
Let’s discuss the importance of precise temperature control in this article.
Importance of Temperature Control in a Process :
Temperature management and control is equally important in process applications. Effective temperature control is key to quality of the final product. Improper temperature control adversely affects energy consumption and production costs, and can also result in safety hazards.
The methods most commonly used for temperature control are :
- Manual temperature control
- Automatic temperature control
- On-off temperature control
- PID based temperature control
Comparison of Temperature Control Methods
Typical On-Off Temperature Control
Suitable for applications with a constant heat load, fast response or quick opening is required.
Application for On-Off temperature control
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Application
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On/Off
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Fast Response/ Quick opening is required
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√
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Constant Heat Load
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√
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Typical PID Temperature Control
PID control ensures the exact set process value is achieved and is suitable for processes with variable set temperature and heat load, where temperature overshoot is not tolerable.
Application for PID temperature control
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Application
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PID
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Accurate Temperature control is required, overshoot is not tolerable
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√
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Variable Set Temperature
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√
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Variable Heat Load
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√
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|
When product quality is dependent on temperature accuracy
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√
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|
When Safety of operation is temperature sensitive
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√
|
Impact of Improper Selection of Temperature Control Method :
Reduced Efficiency
Any control system performs four essential functions - measurement, comparison, computation and correction. In a manual control system all these functions need to be performed by the operator. However, manual operation is prone to human error. Lapses in accuracy and continuity can affect the overall efficiency of the process.
Lower Product Quality and Productivity
Inaccurate temperature control results in stratified consumption profiles leading to low product quality, increase in rejections / rework, and therefore lower productivity.
Operational Safety Hazards
Inaccurate temperature to the steam system can also lead to conditions exceeding the design conditions of equipment, increasing the risk of safety hazards.
Benefits of Automatic Temperature Control
Higher Energy Efficiency
In automatic temperature control systems, the four essential functions of the system, i.e. measurement, comparison, computation and correction are done with help of sensor, controller, control valve with actuator and positioner ensuring optimum accuracy and continuity.
PID type temperature control valves provide the right quantity of steam at right temperature & pressure at all times.
Optimum Product Quality
Accurate control of temperature within desired limits enables consistency in production and ensures optimum product quality, reducing rejection rate / rework for temperature sensitive processes. This further leads to savings in raw material costs.
High Operational Safety
Overheating/ cooling due to inaccurate control may lead to unwarranted / dangerous process conditions. This situation can be eliminated / controlled by automatic pressure control.
The Forbes Marshall Solution
The eVALV from Forbes Marshall is a versatile control valve designed to meet the need of varied process control requirements. It is an innovative 2-port globe valve built to the highest quality standards. Installation of the eVALV on steam lines ensures precise temperature control and controlled utility consumption with optimized and sustained productivity for optimum PQ%.