Category: Process Plants Instrumentation
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Industrial Process Temperature Control System
Let’s consider the industrial process control system shown below: The requirement is to control the temperature ϴ in the tank. The voltage r, obtained from a potentiometer, is calibrated in terms of the desired temperature ϴc. This voltage represents the input quantity to the feedback control system. The actual temperature ϴ, the output quantity, is…
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How to Perform Mass flow Measurements with DP sensors
Let’s assume we are measuring flow by differential-creating primary device for example an orifice plate and a DP cell as illustrated in Figure 1 below: The differential head across the primary device is corrected for temperature variation in the first calculation block, but there is no need for pressure correction because a liquid is virtually…
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Key factors to consider when selecting flowmeters
Selecting the right flow measuring instrument for a given flow application can be a challenging task given the numerous measurement techniques available. In this article, we look at some of the key pointers that can help you in the decision making process. What is discussed here isn’t exhaustive in itself but should act as some…
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Instrumentation and Controls for a Steam Desuperheater
A steam generator is an item of plant equipment that is found in almost every manufacturing site, and its output of steam has many critical uses in a variety of production processes. Steam has been assigned a measurement quality and a scale based on what is known as its dryness, which indicates how much “free”…
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The Instrumentation for Furnace Control
The figure below shows a typical basic furnace used to raise the temperature of a heat-transfer medium that is used on other equipment in a plant process. From the figure above, the temperature of the heat-transfer medium is the parameter that sets the demand on the heating system. The amount of heat required is manually…
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Key Factors to Consider in Selection of Valves
Valves are the final element in a control loop, and are critical in providing the correct flow. The valve, usually operates in very harsh conditions, and is one of the most costly elements in the process control system. Their selection and correct installation require both knowledge and experience. Understanding system requirements and manufacturers specifications is…
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How to Connect a DP (Differential Pressure) Flow Sensor to a DP Transmitter
The DP Transmitter should be mounted with a manifold block as illustrated in the figure 1(a) below to allow for maintenance. Valves B and C are the isolation valves while valve A is an equalizing valve. Valve A is used along with valves B and C to zero the transmitter. In normal operation valve A…