Thermal Mass Flow Meters for Combustion Efficiency Control and Monitoring

Example of inline thermal mass flow meter
Image Courtesy Fox Thermal Instruments

Fox Thermal Instruments, a recognized leader in the manufacture of thermal mass flow meters, has authored a white paper entitled "Reduce Energy Costs and Enhance Emissions Monitoring Systems" which provides a technical view of how the use of thermal mass flow measuring technology can be effectively employed on combustion based systems to provide efficient energy usage. Combustion efficiency contributes to the financial benefit of an operation, as well as enabling compliance with emission requirements.

Thermal mass flow measurement is a well regarded mature technology in industrial process measurement and control applications. The instrument returns a mass flow reading by measuring the heat dissipating effect of the media flow on a temperature sensor. Heat transfer is proportional to the mass flow.

The mass flow measurement instruments are very popular for several reasons. They have no moving parts, have a fairly unobstructed flow path, are accurate over a wide range of flow rates, calculate mass flow rather than volume, measure flow in large or small piping systems, and do not need temperature or pressure compensation.

The white paper is provided below for you to read. It is informative and will prove a good investment of time to read. Share your flow measurement challenges of all types with process instrumentation specialists, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

Thermal Mass Flow Meters Reduce Energy Costs and Enhance Emissions Monitoring from Classic Controls, Inc.

Thoughts on Upside of Outsourcing Industrial Project Work

Many companies that use these liquid metering systems possess
some of the technical and physical resources to design and build
their own. Outsourcing the work can bring the best resources to bear
on the project and free in-house personnel for other tasks.
Photo courtesy Sagebrush Pipeline Equipment

Industrial process measurement and control entails projects, lots of projects. Equipment and instruments that are the life of our processes periodically need modification, replacement, major service or maintenance. Large scale work is generally contracted out for a variety of reasons, not the least of which is that the manpower, equipment, or license and certification requirements are beyond what the stakeholder (the company) may possess . But on smaller projects, an organization is often confronted with the decision of whether to do the work in house or contract it out. There are potential perils and rewards, regardless of the path you take.

The title of this article reveals my leanings on the issue of whether to outsource. Based upon my own project experience and observations of others in their pursuit of project completion, I am generally in favor of it.

Prior to determining whether to use internal or external resources, take the time to document some elemental project requirements.

• What is the starting condition of the project? It is important to systematically assess the existing conditions, as they have a substantive impact on the scope of work needed to be accomplished to reach the point of completion.
• What is to be the ending condition of the project, the definition of completion? There must be a defined ending condition that, once achieved, signals that the project is complete. Start with a general statement and add details garnered from various stakeholders. Keep in mind that the end condition will need to satisfy all stakeholders, so their input should be influential.
• How much time is allowed to complete the work? This pertains to the needs of the company, not the time required to accomplish the task. If there is a deadline for the project, it must be known. An example would be completion of combustion efficiency upgrades prior to the effective date for a new emissions standard. It's not when the work can be done, but when it must be done
• How much time will be required to complete the work? This may be difficult to ascertain at project inception, but some allowance should be assigned to planning, equipment and material procurement, actual hands-on trade and technical work, startup, testing, commissioning, and final documentation and training. This exercise will help you develop a more detailed picture of what is involved in getting the project completed and how long the timeline might be.
• What special trade or technical skills will be required? You may need skilled or certified individuals to perform certain tasks. It is essential to know the extent of these resource requirements.
• Does any of the work require a license or permit? Some extents of modification may require permits from a local jurisdiction and/or licensed trades to perform the work. New work often requires permits. Every jurisdiction has its own set of standards and requirements which must be considered.

Recall that I said document the project requirements. This is important for everyone involved. You want to prevent the drifting of performance benchmarks during the course of the project. This should be especially important if you are the one responsible for project completion. Injections of additional requirements midstream have the potential to destroy your carefully considered plans and result in delays, increased cost, compromised quality, and dissatisfied stakeholders. If somebody wants a change, insist that they be realistic about its impact on the schedule and budget.

There are three major decision factors to consider for in-house or outsourced projects.

• Technical resources: Do you have people on staff with skills and qualifications that match those that will be needed to accomplish all the tasks comprising the project? That may include substantially more than the mechanics needed to install newly acquired parts and equipment. Consider engineering and design, the production of required documentation, procurement and scheduling of materials and equipment, proactive scheduling and coordination of the various tasks, and general project management.
• Special equipment and tools: Are there any particular tools, instruments, or equipment that will be required on the project? Does the organization have these resources on hand? If not, how will they be procured, how long does it take, how much does it cost?
• Available manpower: Are there enough personnel in the organization with the needed skills to complete the work AND is there enough slack available in their schedule to allow a sufficient amount of their time to be devoted to the project to achieve a timely completion? This is critical and applies to both the skilled trade labor and administrative manpower requirements.

An honest and thoughtful consideration of the three areas outlined will likely convince you that, unless the project is small in scale and simple in scope, outsourcing to a contractor with expertise and experience in the work to be accomplished is your best course of action. Sure, dealing with contractors can be difficult and merely outsourcing will not be a panacea for all the challenges presented by any project. However, if a contractor's fulfillment of the three considerations outlined above are better than yours, there is probably advantage in hiring them.

In the big picture, outsourcing can keep your company's resources available to perform tasks more directly related to revenue generation, which is what they were likely hired for in the first place. Outsourcing draws comparatively little from the organization resource pool and, candidly, puts the bulk of the performance burden and the associated aggravation and stress on another organization that is probably better equipped to handled it than you. Done right, it can be a big win for everyone.

Share your process and fluid control projects with experienced professionals and seek out opportunities to be more effective.

Flow Measurement - Sometimes the Simple Solution is Best

These variable area flow meters also permit visible
inspection of flowing media
Courtesy ERDCO Engineering Corp.

For process control and commercial or industrial applications, there are numerous methods of flow measurement from which to choose. Technologies range from very simple applications of physical principles to deployment of very specialized electronics and sensors. The available range of accuracy, response, and cost is quite broad, with a general expectation that higher cost will deliver better performance and accuracy.

Making the best instrument selection for a flow measurement application should include an assessment of what the operators really need in order to safely and effectively run the process or perform the task related to the measurement of fluid flow. Installing instrumentation with capabilities far beyond what is required is almost certainly a waste of financial resources, but may also have an unexpected impact on operators. Through the generation of data that, while accurate, does not provide any actionable information about process condition, operators can be misled, similar to the occurrence of a false or nuisance alarm. Some applications call for high accuracy, some do not. Define your informational needs and select instruments that will meet those needs.

There is a large array of applications that can be satisfied with simpler, less costly measurement technology. These devices often employ turbines or vanes to produce an indication of flow rate. Incorporated into some of the instruments is a means to visually observe the flowing liquid to verify color and clarity. Simple devices sometimes are intended only to indicate the presence of fluid flow, and whether the flow rate is high or low. Configurations are available that allow insertion into lines under pressure (hot tap) through a full port ball valve. Other variants with combinations of features and capabilities abound.

The selection range is enormous, so define your minimum needs first, then search for a compatible product. Your search can be enhanced by contacting an instrumentation specialist. Combining your process expertise with their broad product knowledge will produce effective solutions.

Variable Area Flow Meter - SeeFlo from Classic Controls, Inc.

Pressure Safety Valves

One of many variants of safety valves
for pressurized systems
GE Consolidated

Gases and steam are compressible. It is normal that when gas or steam reaches the disc in a valve, it compresses and builds up before passing through the valve. This compression may cause a rapid build up of system pressure and be potentially harmful. There are other process conditions, such as boiler control malfunction, that can create elevated pressure in a closed system. Every system and component in a pressurized system has a safe operating pressure limit that must not be exceeded.

A conventional liquid type relief type relief valve doesn't open fast enough to relieve gas or steam pressure. The slower action may actually contribute to pressure build-up. A compressible gas system requires a valve that will pop wide open under excessive pressure. That's the design principle behind a pressure safety valve, also called a safety valve, or sometimes a pressure relief valve.

Safety valves and relief valves are similar and share common design and components. The direct acting safety valve is made up of a inlet, outlet, housing, disk, seat, spring, and in some instances, a manual operating lever. The safety valve assembly is protected by the housing which provides appropriate threaded, welded or flanged pipe connection to the system. There will be a means to set the acting pressure of the valve, and specific procedures recommended by the manufacturer should be closely followed when installing and setting the valve. The disk stays in place until the system pressure increases to the point when the disk “pops” off the seat and sends system steam or gas to the outlet. An adjusting screw is commonly used to adjust the valve set point or popping pressure. Spring tension hold the disk against the seat, and can change over time and require recalibration of the adjusting screw.

The popping open of the safety valve is a function of the design of the disk. Among manufacturers of this type of valve, there may be differing methods of producing the same operating result. At the popping pressure, or set point, the disk will slightly lift off the seat. Once that happens, the design of the valve causes the valve to pop fully open quickly.

When the pressure drops to a level below the set point, the same operation happens in reverse, and because the high velocity of the escaping gas, the valve must close quickly and tightly. Otherwise the high velocity will damage the surfaces of the valve opening.

The pressure at which a valve opens all the way, is called the popping pressure. The opposite (rapid closure of the valve) is called positive seating. The difference between the popping pressure and the positive seating is called blowdown. For example if popping pressure is 220 PSI, and the positive sealing pressure is 200 PSI, the blowdown is 20 PSI.

The application of these valves is not a control operation, it is a safety operation. Get properly responsible and qualified individuals involved in selection. Your search for the right valve can be enhanced by consulting with product specialists, with whom you can share your process control and safety requirements and challenges.

GE Consolidated Pressure Relief and Safety Valves from Classic Controls, Inc.

Current to Pneumatic Converter

Current to pneumatic converter
Courtesy Yokogawa

A straight forward device, a current to pneumatic converter produces a pneumatic output signal that is proportional to a control level input signal of 4 to 20 mA or 10 to 50 mA. This provides a useful interface between electronic controllers and pneumatically operated valves, air cylinders, or other air operated control elements.

Pneumatic signals are regularly used throughout many installations as matter of safety, legacy, or because a pneumatic signal can provide motive power to an operating device such as a valve positioner. Electrical control signals can be transmitted long distances across wires to deliver control signals to operating elements. The current to pneumatic converter provides a bridge between the two systems and allows the most beneficial aspects of each to be brought to bear on process operation.

Converters are available in standard variants that accommodate a number of hazardous location designations, as well as several output pressure ranges and calibrations. Share your process control connectivity challenges with application specialists, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

Current To Pneumatic Converter for Process Control from Classic Controls, Inc.