Process industries spanning from chemical and petrochemical to energy, pharmaceutical and water treatment rely on process analyzers to ensure the quality, safety and efficiency of their operations. However, even the most advanced analyzers can be rendered ineffective if the samples they receive are not adequately conditioned. This is where sample handling systems come into play.
The sample handling system is a critical component in the field of process analysis. It serves as the physical assembly of fluid-processing components designed to prepare the sample in a manner that is compatible with the analyzer being used. Beyond material compatibility, a well-designed sample conditioning system must account for and control crucial parameters such as pressure, temperature and flow of the sample. Furthermore, it plays a pivotal role in protecting the analyzer from potential process upsets. In this article, we will delve into the intricacies of sample handling systems for process analyzers, emphasizing their significance in ensuring accurate and representative measurements.
Why Sample Handling Systems?
Generally, the operation of modern process analyzers itself represents few problems. The main challenge lies in obtaining a clean sample, continuously representative of the process being analyzed, and ensuring that the sample is in a condition fully compatible with the analyzer's operation requirements.
A typical sample handling system consists of three core components:
- Sample Tap and Return Points: These are the entry and exit points for the sample within the process. The sampling tap must be strategically located to ensure that it captures a truly representative portion of the process stream. Conversely, the return point should efficiently reintroduce the spent sample back into the process.
- Sample Transport System (Fast Loop): The sample transport system, often referred to as the "fast loop," is responsible for swiftly conveying the sample from the tap to the analyzer. It is essential to minimize transit time to maintain the sample's representativeness and integrity.
- Sample Conditioning System: The sample conditioning system, as discussed earlier, prepares the sample for analysis by adjusting parameters like temperature and pressure and addressing material compatibility. This system ensures that the sample aligns with the specific requirements of the analyzer.
- In situations where there is insufficient pressure to return the analyzer's spent sample to the process, a sample recovery system may be necessary. This system is designed to efficiently collect and return the sample, ensuring minimal waste and environmental impact.
- At times, it becomes necessary to redirect the spent gas sample to a pressurized flare pipeline, which introduces additional complexities due to potential back pressures. In such scenarios, specialized vent recovery systems, leveraging vacuum aspirators, come into play. These systems are meticulously designed to ensure a consistent pressure at the outlet of the analyzer's vent, addressing the unique challenges posed by redirecting samples to pressurized flare pipelines.
In essence, the success of process analyzers hinges not only on the analyzers themselves but equally on the sample handling system. A well-designed and properly executed sample handling system is fundamental to achieving accurate and reliable process analysis. It serves as the bridge between the intricate workings of the analyzer and the dynamic and often challenging conditions within the industrial processes it monitors. Consequently, it demands a high level of technical expertise, attention to detail, and a comprehensive understanding of the specific requirements of each application.
The Core Functions of Sample Handling Systems
- Material compatibility is the foundation upon which sample handling systems are built. Incompatible materials can lead to corrosion, contamination, or other issues that compromise the accuracy of the analysis. Therefore, selecting materials that are chemically resistant to the sampled substances is essential.
- Precise control of pressure, temperature, and flow within the sample handling system is imperative. Variations in these parameters can alter the chemical composition and physical state of the sample, resulting in erroneous readings. The system should maintain these variables within defined tolerances to ensure data reliability.
- Process upsets, which can include sudden pressure spikes or temperature fluctuations, can be detrimental to both the sample conditioning system and the analyzer. Robust design and safety features are necessary to shield the system from these potential disturbances, preserving its integrity and longevity.
- Process sample probes and sample transport lines are integral to obtaining representative samples. These components are meticulously designed to ensure that the sample extracted from the process accurately represents the composition at the point of sampling. Rapid sampling is crucial to capture the dynamic nature of many industrial processes.
- Different analyzers employ various measurement techniques, such as spectroscopy, chromatography or wet chemistry. Sample handling systems must align with these techniques, preparing the sample in a state and condition that facilitates accurate analysis. This often involves processes like filtration, dilution, or temperature regulation to match the analyzer's requirements.
- The importance of timely sample delivery to the analyzer cannot be overstated. The delay between sample extraction and analysis should be minimized to ensure that the data obtained reflects the real-time process conditions. However, the acceptable response time varies depending on the application. Analyzing a representative sample promptly is essential, as it serves as an indicator of process efficiency or deviations. Understanding these time constraints is critical for system designers.
Companies like Modcon have been at the forefront of providing complete integrated analyzer systems and related services. With over 50 years of experience across various industries, Modcon understands the complexities of process analysis. Their expertise extends to designing and manufacturing Analyzer Houses equipped with sample handling systems, essential facilities like air-conditioning, power distribution, lighting, and safety features.
Modcon’s staff has extensive experience with virtually every type of process analyzer, as well as with various forms of packaging such as stainless steel or fiberglass buildings, galvanized-steel buildings, cabinets and racks. Years of in-plant experience guarantee the best available technology in your system designs.
Modcon Analyzers Systems are normally equipped with the following main facilities:
- Analyzer Houses including air-conditioning, power distribution, lighting, termination and junction boxes, gas and flame detection, relevant piping and wiring
- Process sample probes and sample transport lines designed to ensure representative and rapid sampling, avoiding a possibility of contamination or dead volume
- Sample Conditioning systems to provide the sample in a state and condition compatible to the measurement technique used by analyzers
- Sample recovery systems, stream selection facilities, telephone modem connections, furniture, special equipment and tools, etc.
Sample handling systems are the unsung heroes of process analysis. They play a pivotal role in ensuring the compatibility and accuracy of samples delivered to analyzers. Material compatibility, control of critical parameters, protection against process upsets, and the ability to provide timely and representative samples are all essential aspects of these systems. Companies like Modcon exemplify the dedication to excellence in the field, offering integrated analyzer systems that are a testament to years of experience and innovation. As industries continue to demand higher levels of precision and reliability, the importance of sample handling systems in the world of process analysis cannot be overstated.
