How clamp-on flow meters optimize processes
“You can’t control what you aren’t measuring” is an old adage in process control. Many times, process parameters, such as flow rates at the intermediate steps of a complex process, are not actually measured. At best, they are calculated from mass and energy balance equations, which rely on ideal conditions, assumptions and other inaccuracies.
Flow measurements are traditionally expensive, leading many companies to believe it is not necessary to perform them at the intermediate steps. This is a missed opportunity. By adding cost-effective, clamp-on flow meters to the intermediate steps of a process, the entire process can be optimized. The small expense of these meters is quickly returned in raw material, utility and maintenance time savings.
Figure 1. A technician checks the flow rate of a pipe using a clamp-on meter. Source: Panametrics
Understanding the intermediate steps
Often, engineers have a good idea of what materials go into the first step of a process, and they know about what materials come out of it. Then, they rely on mass and energy balance equations to fill in the gaps between the starting and final products. However, to fully understand a process, it is worth verifying the flow rates of intermediate steps to adjust the mass and energy balances. By doing so, waste stream flows are reduced and energy can be consumed more efficiently.
Measuring the flow rate at the intermediate steps can be used to more accurately gauge the efficiency of the process as a whole. If the intermediate flow rates are measured and understood, separation process selectivity can be better characterized, utility usage more accurately tracked and so on. From there, mass and energy balances are verified and adjusted. This allows for maintenance schedules, process parameters and other criteria to be optimized, which results in immediate cost savings.
Clamp-on flow measurements
Differential pressure meters used across an orifice plate are an accurate way to measure flow. These are expensive and time consuming to install. Furthermore, the process line must be shut down, Job Hazard Analysis (JHA) performed and other such constraints to install them. Instead, clamp-on flow meters can be used to measure flow without having to cut pipelines, which reduces costs and hazards significantly.
Panametrics has developed several ultrasonic, clamp-on flow meters for measuring fluid flow. These clamp-on meters can be installed quickly, without cutting the pipe, unlike orifice plate meters. Clamp-on meters have no moving parts, making them low maintenance and long-lasting as well.
In terms of accuracy, clamp-on meters are within 1% to 2% of the actual flow rate. This accuracy is enough to verify or adjust mass and energy balance equations for troubleshooting or optimization purposes. Also, because they do not contact the process fluid, they are contamination free.
Characterizing and understanding a process fully will require flow measurements throughout, not just at the input and output streams. Clamp-on flow measurements by Panametrics can measure these intermediate streams.