Application of Non-Invasive Flow Meter Technology to Extreme Temperature Lines

One configuration of Flexim WaveInjector, allowing
non-invasive flow measurement at extreme temperatures.
Image courtesy Flexim Americas Corp.

The development of condensate in super heater and re-heater drains can lead to trouble in combined cycle and cogeneration plants with heat recovery steam generators (HRSGs). The need to reliably detect and measure condensate in these drain lines has emerged as an area needing attention.

The Problem

Heat recovery steam generators were never designed for cyclic service. The move toward renewable energy resources (such as wind and photovoltaic), in tandem with the ability of the combined cycle plant to start-up and stop quickly, is expanding the role of the combined cycle plant as a backup source of power. With frequent starts/stops condensate management can be challenging. Draining the condensate is critically important for the safe and reliable operation of the boiler. While the problem of condensate drainage has been around for years, the problem is greater now in installations with a higher frequency of cycling. The importance of finding a good solution for detecting condensate in the HRSG drain lines is growing.

Boiler manufacturers address this situation through the use of condensate pots, level instruments, site glasses, and valves. None of these technologies provide a satisfactory combination of reliability, economy, and efficiency. Knowing when steam converts to water is difficult with this approach. Plus, over cautious systems sometimes release steam instead of condensate, wasting energy. A more reliable and consistent way to sense the presence of water in drain lines had to be found.

The Solution

By designing specialized mounting and tooling, modifying their sensing diagnostics, putting in hundreds of hours of field testing, and investing hundreds of hours improving their firmware for water detection, the manufacturer Flexim developed an ultrasonic flow meter that elegantly and reliably solves the HRSG drain line problem.

These clamp-on sensors work by measuring the transit-time difference of an ultrasonic signal, at varying flow velocities, through the process media. Ultrasonic, clamp-on flow meters have no moving parts, are not affected by density, and are mounted directly to the pipe in a non-invasive fashion.

The most challenging aspects of this application are the exposure of the sensing units to high temperature and the thick-walled pipes with small diameters commonly used for drains. To handle the high temperatures, specialized mounting and tooling were developed for the sensor allowing for pipe temperatures up to 750 deg. F. To overcome the small diameter / thick pipe issue, Flexim engineers reconfigured the sensor’s firmware to change from measuring flow rate, and instead measure noise (decibels) as an innovative way to distinguish steam from water.

Flexim’s unique ability to measure the presence of liquid in condensate drain pipes is a revolutionary development. This valuable solution helps customers run longer and safer, minimizing downtime. Share your measurement challenges with process measurement specialists, leveraging your own knowledge and experience with their product application expertise to develop an effective solution.

HVAC Energy Management - Thermal Metering With Non-Invasive Technology

Ultrasonic flow measurement is an optimal choice
for thermal metering, with it non-invasive installation.
Image courtesy Flexim Americas Corp.

The modern business climate has, for some time now, been spooling up demand for accountability and, even more so, efficiency. Whether you think of efficiency as "doing more with less" or just avoiding the expenditure of financial, human, or natural resources the end result is the same and calls for similar prerequisites.

We live in a society of buildings, each with a mapped out function. Most buildings are predominantly occupied by people, bringing a requirement to maintain temperature, relative humidity, and air quality at levels of suitable comfort for human occupants. The energy consumption involved with providing that level of comfort stands as a bold line item in the operating expense ledger for any building. That is where accountability and efficiency come in. It is in the building stakeholders' interest to have knowledge regarding rates and quantity of thermal energy usage, as well as efficiency measures of delivered output per unit of input energy.

HVAC (Heating, Ventilation, Air Conditioning) primarily is an endeavor that generates and moves thermal energy throughout an enclosed space. Commercially available technology now allows a building operator to accurately measure that movement of thermal energy throughout a system or building. The process is generally called BTU metering and has a number of justifiable benefits.

• Real time equipment performance measurement.
• Sub metering can indicate specific areas of consumption.
• Ability to directly bill multiple tenants in a single building for their thermal energy usage.
• Monitor and balance energy flows.

BTU metering essentially involves inlet and outlet temperature measurement of heat transfer liquids, along with their flow rate. While the principle is simple, the intricacies of the measurement methods and equipment accuracy can have a substantial impact on the accuracy, and thus the benefit, of the measurement data. Additionally, adding more instrumentation to an already complex system can create an additional on-going maintenance and calibration burden to retain the necessary levels of accuracy and function. Success at gaining the benefit of the performance data while minimizing the additional maintenance burden due to the instrumentation should be the goal.

One solution calls for the use of clamp on ultrasonic flow meters to measure liquid flow, coupled with temperature measurement in a single unit that will perform necessary calculations and provide output data in useful engineering units. An overarching benefit of the clamp on meter is its non-invasive nature, allowing its retrofit to in-place systems with no disturbance to existing piping. Here are some other characteristics of a highly effective BTU measurement unit:

• No wear mechanism as part of the flow measurement unit
• Traceable accuracy of flow and temperature measurements
• Simple installation in new or retrofit applications without disruption to system operation
• Reliable and maintenance free operation
• Accurate measurement from near zero flow rate to maximum system flow
• Stable sensing with no zero drift
• Communications protocol to match building energy management system
• Large storage cache for data, in case of communication failure
• Common output signals, 4-20 ma or other, usable with selected ancillary equipment

Selecting the right equipment or instrumentation is the most important step along the path of adding measurement capability to increase efficiency. Without a solid stream of reliable data, useful decisions become difficult. Contact a product application specialist and share your goals and challenges. Leverage your own knowledge and experience with their product application expertise to develop an effective solution.

BTU Metering Using Non-Invasive Flow Measurement from Classic Controls, Inc.

Industrial Process Pressure Transmitters

One of many variants of industrial pressure transmitters.
Image courtesy Yokogawa USA

The measurement and control of fluid pressure is ubiquitous throughout many industrial processes. Measurements of pressure, directly and indirectly, provide real time information about what is happening in places that cannot be seen, such as inside a pipe, tank, or machine. The very nature of “process” suggests movement and change, the control of which is necessary to produce a consistent desirable outcome. Industrial pressure transmitters employ specific technologies and physical principals to derive a measurement of process pressure, then deliver or transmit, the measured value to a controller or recording device.

Fluid pressure tells a process operator much about what is currently happening. The pressure variable can be used to determine, among many industrial process elements:

• Degree to which the process is conforming to a recipe or specification
• Whether machinery is performing within its specified operation range
• If conditions of the process remain within the bounds established for safety
• A quantity measurement of flow, mass, or volume

Global industrial processes have widely varying physical arrangements, operating environments, and measurement requirements. Manufacturers of industrial pressure transmitters have responded with an immense array of transmitter technologies, arrangements, and configurations. When selecting the best suited pressure transmitter for your application, consult a sales engineer and consider some of the following:

• Signal requirements – Type, distance, possible sources of interference
• Device environment – Hazards, extreme conditions of temperature or corrosion
• Accuracy and stability of measurement
• Response time to changes in the process condition
• Ratings and certifications required for the device
• Configuration, arrangement, and mounting aspects of the transmitter device

Explore the differing technologies and how they can be best applied to implement or improve your process. Experienced sales engineers are a useful sounding board for discussing your needs. Share you process measurement challenges with them and leverage your own knowledge and experience into an effective solution.

Coalescing Filters For Compressed Air

Coalescing filters for industrial compressed air service.
Image courtesy Parker Hannafin - Balston Div.

Coalescing filters remove liquid aerosols from a gas by causing very small droplets to contact others, forming successively larger liquid droplets that eventually are moved via gravity to a drain. A combination of filter media and housing properly direct an inlet stream to maximize the combining, or coalescing, of the fine droplets. The filter media will also serve to trap solid particulates, as well. An automatic drain arrangement is a useful feature that prevents accumulation of liquid in the filter housing without operator attention.

Compressed air systems will typically produce output that contains moisture and small amounts of liquid lubrication oil. Leaving the compressor, the air is hot. As it cools, the moisture will condense in the piping system and utilization equipment without a means to remove it. Coalescing filters, properly located throughout the system, will trap and remove liquids entrained in the compressed air stream. The nature of the filter media also results in efficient capture of solid contaminants, such as rust, dust, welding flash and more.

The installation must route the compressed air through the filter in the proper direction. Improperly piped units can have their automatic drain function inhibited, leading to failure and a need to reconnect the unit correctly. Size selection is simplified with tables providing maximum flow rate for rated filtration performance. Oversizing a selection will not produce a negative impact. The filter media pressure drop increases as solids are collected and retained, requiring replacement when pressure drop is excessive.

Share your compressed air system requirements and challenges with filtration specialists. Leverage your own knowledge and experience with their product application expertise to develop an effective solution.

Compressed Coalescing Filters for Industrial Use from Classic Controls, Inc.