Thursday, March 23, 2017

Train Your People for Better Plant Steam and Hot Water Systems

Do the people who maintain your plant’s steam system really understand how to save you money?

It's probably a good idea to have them attend a professional steam and hot water training seminar. These programs provide a window into elements of the plant steam cycle as they observe live steam and condensate behavior in glass piping and glass-bodied steam traps under differing conditions. They gain very useful knowledge regarding:
  • Steam generation 
  • Distribution 
  • Control & Heat transfer 
  • Heat Recovery opportunities 
  • Condensate removal & return
Mead O'Brien, a company with decades of experience in industrial and commercial steam and hot water systems provides such training. See their video below:

Thursday, March 16, 2017

The Application of Heat in Industrial Applications

Heat exchanger
Heat exchanger (courtesy of Armstrong)
The measurement and control of heat related to fluid processing is a vital industrial function, and relies on regulating the heat content of a fluid to achieve a desired temperature and outcome.

The manipulation of a substance's heat content is based on the central principle of specific heat, which is a measure of heat energy content per unit of mass. Heat is a quantified expression of a systems internal energy. Though heat is not considered a fluid, it behaves, and can be manipulated, in some similar respects. Heat flows from points of higher temperature to those of lower temperature, just as a fluid will flow from a point of higher pressure to one of lower pressure. 

A heat exchanger provides an example of how the temperature of two fluids can be manipulated to regulate the flow or transfer of heat. Despite the design differences in heat exchanger types, the basic rules and objectives are the same. Heat energy from one fluid is passed to another across a barrier that prevents contact and mixing of the two fluids. By regulating temperature and flow of one stream, an operator can exert control over the heat content, or temperature, of another. These flows can either be gases or liquids. Heat exchangers raise or lower the temperature of these streams by transferring heat between them. 

Recognizing the heat content of a fluid as a representation of energy helps with understanding how the moderation of energy content can be vital to process control. Controlling temperature in a process can also provide control of reactions among process components, or physical properties of fluids that can lead to desired or improved outcomes.
 
Heat can be added to a system in a number of familiar ways. Heat exchangers enable the use of steam, gas, hot water, oil, and other fluids to deliver heat energy. Other methods may employ direct contact between a heated object (such as an electric heating element) or medium and the process fluid. While these means sound different, they all achieve heat transfer by applying at least one of three core transfer mechanisms: conduction, convection, and radiation. Conduction involves the transfer of heat energy through physical contact among materials. Shell and tube heat exchangers rely on the conduction of heat by the tube walls to transfer energy between the fluid inside the tube and the fluid contained within the shell. Convection relates to heat transfer due to the movement of fluids, the mixing of fluids with differing temperature. Radiant heat transfer relies on electromagnetic waves and does not require a transfer medium, such as air or liquid. These central explanations are the foundation for the various processes used to regulate systems in industrial control environments.

The manner in which heat is to be applied or removed is an important consideration in the design of a process system. The ability to control temperature and rate at which heat is transferred in a process depends in large part on the methods, materials, and media used to accomplish the task. 

Tuesday, February 28, 2017

Don’t Overlook the Value of Valve Automation Professionals on Your Next Valve Project

Sales and Engineering Professionals
Sales and Engineering Professionals are there to assist
and save you time and money.
Local distributors and representatives who sell industrial valves, actuators and controls also provide services and equipment that will save you time, money, and help you achieve a better outcome for the entire project.

Projects requiring engineered valve systems are best completed and accomplished through the proper selection and application of the valves, actuators, positioners, limit switches and other associated components. A great resource exists, ready to provide a high level of technical knowledge and assistance, that can be easily tapped to help you with your project - the valve automation sales professional.


Consider a few elements the valve automation professional brings to your project:

Product Knowledge: Valve automation professionals are current on product offerings, proper application technique, and product capabilities. They also posses  information on future product obsolescence and upcoming new designs. This type of information is not generally accessible to the public via the Internet.

Experience: As a project engineer, you may be treading on new ground regarding some aspects of your current valve system design assignment. There can be real benefit in connecting to an experienced and highly knowledgable source, with past exposure to your current challenges.

Access: Through a valve automation professional, you may be able to establish a connection to “behind the scenes” manufacturer contacts with essential information not publicly available. The rep knows people at the factories, a well as at other valve related companies, who can provide quick and accurate answers to your valve automation related questions.

Of course, any valve actuation or automation solution proposed are likely to be based upon the products sold by the representative. That is where considering and evaluating the benefits of any solution becomes part of achieving the best project outcome.

Develop a professional, mutually beneficial relationship with a local valve automation professional to make your design job go after, more efficiently, and more cost effective. Their success is tied to your success, and they are eager to help you.

For assistance with any industrial valve automation requirement, contact Mead O'Brien at (800) 892-2769 or visit http://www.meadobrien.com.

Monday, February 27, 2017

Pressure Reducing Valves and Temperature Regulators

Pressure reducing valves
Pressure reducing valves
(courtesy of Armstrong)
Pressure reducing valves (PRVs) and temperature regulators help you manage steam, air and liquid systems safely and efficiently. And they ensure uninterrupted productivity by maintaining constant pressure or temperature for process control.

Steam, liquids and gases usually flow at high pressure to the points of use. At these points, a pressure reducing valve lowers the pressure for safety and efficiency, and to match the requirements of the application. There are three types of PRVs.

  1. Direct-Acting. The simplest of PRVs, the direct-acting type, operates with either a flat diaphragm or convoluted bellows. Since it is self-contained, it does not need an external sensing line downstream to operate. It is the smallest and most economical of the three types and is designed for low to moderate flows. Accuracy of direct-acting PRVs is typically +/- 10% of the downstream set point.
  2. Internally Piloted Piston-Operated. This type of PRV incorporates two valves-a pilot and main valve-in one unit. The pilot valve has a design similar to that of the direct-acting valve. The discharge from the pilot valve acts on top of a piston, which opens the main valve. This design makes use of inlet pressure in opening a large main valve than could otherwise be opened directly. As a result, there is greater capacity per line size and greater accuracy (+/- 5%) than with the direct-acting valve. As with direct-acting valves, the pressure is sensed internally, eliminating the need for an external sensing line.
  3. Externally Piloted. In this type, double diaphragms replace the piston operator of the internally piloted design. This increased diaphragm area can open a large main valve, allowing a greater capacity per line size than the internally piloted valve. In addition, the diaphragms are more sensitive to pressure changes, and that means accuracy of +/- 1%. This greater accuracy is due to the location, external to the valve, of the sensing line, where there is less turbulence. This valve also offers the flexibility to use different types of pilot valves (i.e., pressure, temperature, air- loaded, solenoid or combinations).
Designed for steam, water and non-corrosive liquid service, self-actuated temperature regulators are compact, high-performance units. They operate simply and are therefore suitable for a wide variety of applications. Flexible mounting positions for the sensor, interchangeable capillaries and varied temperature ranges make installation, adjustment and maintenance quick and easy.

For more information on pressure reducing valves, contact Mead O'Brien at (800) 892-2769 or visit http://www.meadobrien.com.

Saturday, February 25, 2017

A Valve Controller Designed to Operate on All Control Valve Actuators in All Industries

Neles ND9000
Neles ND9000

Metso's Neles ND9000 is a top class intelligent valve controller designed to operate on all control valve actuators and in all industry areas. It guarantees end product quality in all operating conditions with unique diagnostics and incomparable performance features. ND9000 is a reliable and future-proof investment with Metso FieldCareTM life-time support.

Features
  • Benchmark control performance on rotary and linear valves
  • Superior diagnostics and data storage capabilities
  • Local and remote configuration
  • Easy interpretation of diagnostics data
  • Efficient mounting program for all types of actuators
  • Low power consumption
  • Available for HART, PROFIBUS-PA and FOUNDATION Fieldbus networks
  • Reliable and robust design
  • Device self diagnostics
  • On-line, performance and communication diagnostics
  • Hot swap support: possibility to install also on valves that are in process with 1-point calibration feature
  • SIL 2 approved device
Benefits
  • Minimize variability
  • Open solution based on FDT technology
  • Supports Electronic Device Description Language (EDDL) technology
  • Total cost of ownership
  • Easy to use
  • Open solution
  • Product relibilty
  • Prevention and prediction
Applications
  • ND9000 can be integrated with all major DCS systems
  • Mounting kits for any 3rd party actuators
  • Remote mounting
  • SIL 2 approved
  • Marine approved

Friday, February 10, 2017

What are Magnetic Flowmeters and How Do They Work?

Magnetic Flowmeter
Magnetic Flowmeter
(courtesy of Foxboro Schneider Electric)
Crucial aspects of process control include the ability to accurately determine qualities and quantities of materials. In terms of appraising and working with fluids (such as liquids, steam, and gases) the flowmeter is a staple tool, with the simple goal of expressing the delivery of a subject fluid in a quantified manner. Measurement of media flow velocity can be used, along with other conditions, to determine volumetric or mass flow. The magnetic flowmeter, also called a magmeter, is one of several technologies used to measure fluid flow.

In general, magnetic flowmeters are sturdy, reliable devices able to withstand hazardous environments while returning precise measurements to operators of a wide variety of processes. The magnetic flowmeter has no moving parts. The operational principle of the device is powered by Faraday's Law, a fundamental scientific understanding which states that a voltage will be induced across any conductor moving at a right angle through a magnetic field, with the voltage being proportional to the velocity of the conductor. The principle allows for an inherently hard-to-measure quality of a substance to be expressed via the magmeter. In a magmeter application, the meter produces the magnetic field referred to in Faraday's Law. The conductor is the fluid. The actual measurement of a magnetic flowmeter is the induced voltage corresponding to fluid velocity. This can be used to determine volumetric flow and mass flow when combined with other measurements.  

The magnetic flowmeter technology is not impacted by temperature, pressure, or density of the subject fluid. It is however, necessary to fill the entire cross section of the pipe in order to derive useful volumetric flow measurements. Faraday's Law relies on conductivity, so the fluid being measured has to be electrically conductive. Many hydrocarbons are not sufficiently conductive for a flow measurement using this method, nor are gases.

Magnetic Flowmeter and transmitter
Magnetic Flowmeter and controller.
(courtesy of Foxboro Schneider Electric)
Magmeters apply Faraday's law by using two charged magnetic coils; fluid passes through the magnetic field produced by the coils. A precise measurement of the voltage generated in the fluid will be proportional to fluid velocity. The relationship between voltage and flow is theoretically a linear expression, yet some outside factors may present barriers and complications in the interaction of the instrument with the subject fluid. These complications include a higher amount of voltage in the liquid being processed, and coupling issues between the signal circuit, power source, and/or connective leads of both an inductive and capacitive nature.

In addition to salient factors such as price, accuracy, ease of use, and the size-scale of the flowmeter in relation to the fluid system, there are multiple reasons why magmeters are the unit of choice for certain applications. They are resistant to corrosion, and can provide accurate measurement of dirty fluids ñ making them suitable for wastewater measurement. As mentioned, there are no moving parts in a magmeter, keeping maintenance to a minimum. Power requirements are also low. Instruments are available in a wide range of configurations, sizes, and construction materials to accommodate various process installation requirements. 

As with all process measurement instruments, proper selection, configuration, and installation are the real keys to a successful project. Share your flow measurement challenges of all types with a process measurement specialist, combining your process knowledge with their product application expertise to develop an effective solution.

Tuesday, January 31, 2017

Vent Management on Large Cavity Steam Heat Exchange Equipment Commonly Found in the Brewing Industries: Thermostatic Air Vents (TAV) and Vacuum Breakers (VB)

brewery
The following represents a primer on vent management devices on steam heat exchange equipment: TAVs, VBs, and the combination device, model TAVB-3. In order to do that, we will review the purpose and proper application of the devices to establish clarity.

What are Vacuum Breakers and why do we need them?

Vacuum breakers are spring-loaded valve and seat devices that are mounted on or near the steam space of a heat exchanger allowing steam pressurization of the space, but during throttling down or shut off of steam supply also allow the valve to overcome the spring force and open when vacuum is present. The vacuum is formed when steam, with its much higher specific volume than water, condenses to water with heat exchange and is not replaced in the heat exchange space with an equivalent volume of steam, i.e. when the control valve is throttling down from its process design maximum flow, or when steam is being shut off after completion of the process step. By “breaking” the sub-atmospheric condition which occurs in those situations by allowing air into what was the steam space through the open vacuum breaker device; condensate drainage from the heat exchanger by gravity is enabled. This prevents water hammer, internal corrosion, gasket or joint leakage, and potential damage to the heat exchanger and other equipment. Without this device, a reverse pressure differential is formed in the steam space due to vacuum which will suck available condensate from the return system into the calandria, coil, or other large cavity heat exchanger.
Thermostatic  Air Vent/Vacuum Breaker
Stainless Steel Thermostatic
Air Vent/Vacuum
Breaker (TAVB)

What are Thermostatic Air Vents and why do we need them?

Thermostatic air vents (TAV) are also valve and seat devices that are actuated by temperature, typically a “balanced” bellows. The bellows has an alcohol and water charge inside that evaporates and expands on temperature increase approaching the steam saturation curve for the particular steam pressure. The expanding bellows drives the valve into the seat and closes the device. On steam start-up of the heat exchanger, cool air is expelled quickly by using this device until steam reaches it which quickly closes the valve. Similarly, on decreasing temperature, at some point a few degrees lower than the steam saturation curve, the mixture in the bellows condenses and contracts the bellows which pulls the valve plug away from the seat and thus opens the vent. This signifies that non-condensable gases have accumulated and the temperature has depressed enough to allow the valve to open and expel them from the steam space. Pressure is inconsequential up to the TAV design pressure since the alcohol charge is designed to follow the steam saturation curve, offset but parallel, always activating a few degrees below saturation temperature for any given pressure (including vacuum).

Doesn’t the Steam Trap do this as one of its functions?

It is true that one of the three primary functions of the steam trap is to remove non-condensable gases. By virtue of the modularization of steam supply and condensate removal equipment at some distance away from the internal heat exchangers of kettles and cookers for example due to floor space restrictions in the brew house, size, configuration, and internal area of heat transfer equipment in modern breweries and the demands of production, it is imperative that these supplemental devices be used to remove these gases as close and as quickly as possible to the area where they would be entrapped: opposite the steam supply connection of the exchanger.

Why is it so important that air be removed?

There are several reasons, but most importantly, air is an excellent insulator and, without removal, serves to insulate internal heat transfer surfaces from the steam trying to transfer its latent heat. Surface temperature drops of 20-30% are not uncommon with systems unable to effectively remove non-condensable gases. From a secondary standpoint, air and other gases create internal oxidation and corrosion that corrode the system from the inside out. As we already know, a major source of air in the system comes from the vacuum breakers which contribute to piping oxidation if the air is not removed. CO2 entrained in steam turn condensate into carbonic acid (H2CO3) when turned into solution if not removed.

These two devices, TAVs and VBs, are frequently confused as to their function. Remember that TAVs primarily expel non-condensable gases and air on startup; and VBs primarily allow air in on shutdown. Their mounting is critical to their successful operation. Observe the following rules for mounting:
  • As close to the exchanger as possible on a line with a vertical accumulator, if not on the exchanger itself, opposite the steam supply. 
  • Condensate line must be large enough to allow disengagement if horizontal or a vertical accumulator will be needed. If not, the TAV will discharge condensate which means it is not discharging air. The vacuum breaker will spit and leak over time as well. 
  • The vertical accumulator is used to provide an accumulation area for non-condensables. It is typically 2” or larger pipe, approximately 2 ft. high if space allows. An isolation valve should be used between the accumulator and the TAV to isolate for maintenance or system air testing. Note that these devices should be excluded from any air test boundaries since the bellows is “balanced,” meaning that steam pressure has a corresponding saturation temperature to “balance” internal pressure of the bellows against external pressure caused by the steam pressure. Air would not allow this balance to take place and would either not close the valve on the air test, or would rupture the bellows if the isolation valve were downstream. 
Since mounting preferences are similar for both vacuum breakers and air vents, a new device has been developed which accomplishes both functions in one device. This is the TAVB-3 which has become standard at a large brewing company.

Article written by Steve Huffman, Mead O'Brien, Inc.