Safety is a top priority in the world of hydrocarbon refining, where the potential hazards of toxic and combustible gases, as well as the risk of open flames, require constant attention and precautionary measures. To ensure efficient and cost-effective operations, these facilities rely on complex processes and equipment that often operate at extreme temperatures and pressures while maintaining a high-volume throughput. Despite the challenges, maintaining a strong culture of safety remains paramount.
However, these risks can be further compounded in areas near flammable storage tank farms, pipelines, or offloading docks, where an incident can quickly escalate and cause widespread damage. The consequences of such an accident can be catastrophic, leading to the loss of life, extensive damage to equipment and facilities, and even affecting the surrounding community. Thus, it is crucial for these facilities to prioritize safety measures and prevention strategies to mitigate these risks and ensure the safety of both their employees and the environment.
Advanced gas and flame detection systems offer a dependable and intelligent solution to prevent gas and flame-related incidents. With high communication and intelligence capabilities, these systems aim to be reliable, low-maintenance, and cost-effective.
Under the best of circumstances, gas and flame detection is complex. Refineries and processing plants are typically large and often have high-density layouts of tightly placed equipment, piping, and tanks. Processing areas that require gas and flame detection are often partially or fully exposed to the outdoors, subjecting gas monitors to heat, humidity, fog, rain, and wind.
For these reasons, no single gas or flame sensing technology is appropriate for all applications or situations or geographic location. Depending on the individual plant site, the surrounding environment and the nature of the leak source, a gas or flame sensing technology that is appropriate in one place may not be appropriate in another.
Detecting gases and flames is a complex task due to the varying chemistry of gases and other factors that can influence their movement and behavior. Factors such as differences in gas density and the movement of gas clouds in the wind require a comprehensive approach to gas detection. Flame detection can also be complicated by reflected light off shiny surfaces, leading to false alarms. The design of gas and flame systems must account for these and other factors to ensure accurate and reliable detection.
Let’s start by reviewing the elements of a gas and flame monitoring system (Fig 1). These systems continuously provide protection against life-safety hazards and abnormal situations in processing and other plants. The hazards include fires, combustible gas leaks, and toxic gas releases. They also monitor related information, such as manually initiated alarms, wind direction, and system operational status (maintenance alerts).
They detect flames, fires, gases, smoke, heat, and other device-initiating signals. Their operational logic is typically defined within a cause/effect matrix. Once a programmed gas or flame parameter is detected, the fire and gas system initiates alarm warning systems and hazard mitigation equipment including fire suppression. It could be argued that the most critical elements in configuring a gas and flame monitoring system are the detectors themselves and the system controller.
The various gas sensing technologies provide different coverage profiles and capabilities. Some are designed for point localized monitoring, others protect a wider area and still others are suitable for perimeter monitoring of larger areas. For example, catalytic bead, infrared (IR), and electrochemical sensors are designed for point monitoring while ultrasonic acoustic gas detectors provide area monitoring and open path monitors are used in perimeter monitoring. Some point H2S/CO sensors offer TruCal® technology, which provides higher levels of safety.
There are multiple flame detector technologies as well, which can be categorized as point, area, and perimeter monitors. The most popular systems use optical methods to detect flames. They detect the absorption of light at specific wavelengths. Two common optical flame detector types are (1) combination ultraviolet/infrared (UV/IR) and (2) multi-spectrum infrared (MSIR). These devices are sensitive to more than one band on the energy spectrum and therefore are less likely to produce a false alarm. Both technologies function well either indoors or outdoors and provide a reasonably fast response time.
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