A blog specializing in pressure, temperature, level and flow instrumentation, control valves, process analyzers, and all other areas of process measurement. Courtesy of Miller Energy, a New Jersey, New York, Pennsylvania, and Ohio process instrumentation Rep and Distributor.
Showing posts with label Delaware. Show all posts
Showing posts with label Delaware. Show all posts
How to Select a Pressure Switch
UEC One Series Switch Transmitter Hybrid |
Reprinted with permission from United Electric Controls
Pressure switches are widely used by many industries and within many applications. The basic function of a pressure switch is to detect a pressure change and convert it into an electrical signal function – typically on/off or off/on. Pressure switches may be of electro-mechanical or electronic/solid-state design (see our ONE Series); and while each may have its advantages, arriving at the correct pressure switch for your application is the same.
Set Point & Deadband
Application set point (sp) is the desired value reached at rising or falling pressure at which the micro-switch changes electrical states. Depending upon the pressure switch function, the micro-switch could be wired to open (turn something OFF) or close (turn something ON) when set point is achieved, thereby triggering an event such as an alarm, equipment shutdown, or powering up secondary equipment. Ideally, the set point should fall into the mid 50% of the pressure switch range for best performance including repeatability and long life. On an electro-mechanical pressure switch, set point may be adjusted internally or externally either through blind adjustment or reference dial. An electronic pressure switch would have internal or external adjustment via a key pad and digital display or a handheld programmer.
Deadband (DB) is the on-off differential required to reset the micro-switch. This value may be fixed or adjustable with an electro-mechanical switch and may be up to 100% adjustable on an electronic switch.
Deadband may be an important factor to consider depending upon the application requirements.
System Pressure
Knowing your normal and maximum system pressures will help in selecting a pressure switch with appropriate minimum and maximum operating parameters. Once your set point is established, other factors to consider are vacuum and/or surge pressure that could affect switch operation. This would involve maximum working pressure, over range pressure, and proof pressure specifications of a pressure switch. The relationship between set point and system pressure has a direct effect on switch performance and life.
Electrical Considerations
UEC 100 Series Pressure Switch |
An electronic pressure switch would use solid-state relays to change states. Like an electro-mechanical switch, the electronic switch can be programmed to open or close on rising or falling pressure. There are different capacities for switching voltage and current depending upon the application requirements.
Process Media and Wetted Parts
The pressure connection and sensor are known as wetted parts since they come into direct contact with the process media. Sensor material is either elastomer (i.e. Buna-N, Teflon®) or metallic (i.e. Brass, Stainless Steel) with metallic or composite pressure connections. The process media must be compatible with the wetted parts material. Process media temperature should also be considered as each of the different wetted materials would have differing operating properties.
Pressure Switch Mounting
If the unit is to be installed directly onto the process, there are many methods of installation.
Typically a 1/8”, 1/4”, or 1/2” NPT (national pipe thread taper) connection is used with a mating
fitting to secure the pressure switch to the process. There are also straight threaded (SAE, BSPT)
connections, flush mount connections, and sanitary connections. The pressure switch may be
mounted directly in the process line using the threaded connection, a manifold, or flange; or the
enclosure could be bolted to a mounting plate or other plane to secure it. If heavy vibration is
present, you may choose to use a remote diaphragm seal with the pressure switch. The diaphragm
seal mates with the process connection while the pressure switch enclosure is mounted securely
away from the vibration.
Process Environment
It is important to know what type of environment the pressure switch would be installed in – hazardous or ordinary location; indoors or outdoors; exposed to salt air; inside a control panel; in high ambient temperature. These are just some of the factors to consider so the right enclosure type is chosen. Enclosure types come in many shapes, sizes, and materials. They also conform to various industry and third-party approval standards. Electronic switches can be used to replace electro-mechanical switches when SIL is needed for safety applications. There are also electro-mechanical pressure switches without enclosures; typically used in OEM, non-hazardous locations where the environment is benign.
With careful consideration of all the factors listed above, choosing a pressure switch is a snap. If you are at all unsure, please contact your local United Electric Distributor or visit the UE Product Selector to find your pressure switch.
Miller Energy, Inc. - Expertly Serving These Industries in the Mid-Atlantic Region
Miller Energy is a Manufacturer's Representative and Distributor of Industrial Instrumentation and Process Control Equipment with offices in South Plainfield, NJ and Exton, PA. In business since Since 1958, Miller's success is attributable to their commitment to exceeding their customers expectations and a comprehensive line of "best-of-breed" measurement, control, and communication products. With a strong reputation for unparalleled customer service and expert local technical support, Miller Energy continues to demonstrate strong growth in the Mid-Atlantic region.
https://millerenergy.com
908-755-6700 NJ
610-363-6200 PA
https://millerenergy.com
908-755-6700 NJ
610-363-6200 PA
Radiometric, Non-contact Level Measurement for Liquids or Solids
Radiometric level detection (RONAN) |
These level gauges meet “As-Low-As-Reasonably-Achievable” (ALARA) guidelines. Source activity is customized depending on vessel and process parameters such as diameter, wall thickness, material, and measurement span to ensure optimum sensitivity, economy and safety while keeping the source activity to a minimum.
Sources and Detector Mounted External to Vessel |
Operation
Radiometric level measurement provides a safe and efficient, non-contact method to measure liquids or solids in harsh process environments. Each system consists of a gamma source, detector and microprocessor.
- The gamma source, typically mounted external to the vessel emits energy through the vessel walls collimated in a direction towards the detector mounted on the opposite side of the vessel. The gamma energy reaches the detector when the vessel is empty. As the process level rises in the vessel, the gamma energy reaching the detector will decrease in an inversely proportional relationship to the level.
- The detector measures the level of energy and sends a proportional signal to the microprocessor.
- The microprocessor linearizes, filters, and correlates this signal to a level measurement.
The entire system is mounted external to the vessel and can be easily installed and maintained while the process is running ... without expensive down time, vessel modifications or chance of accidental release.
Applications
Low Level Source and Detector Mounted External to Vessel |
- Radiometric level detection
- Low Level Source and Detector
- Mounted External to Vessel
- Solids or Liquid Measurement
- Measurement Not Affected by:
- Internal Obstructions. i.e. Agitators Extreme Process Temperatures
- Caustic Processes
- Violent Product Flow
- Sterile Process
- Changing Process
- Variable Product Flow
- Automatic Compensation for Vapor Density Changes
- Automatic Compensation for Foam or Gasses
- Automatic Compensation for Process Build-Up
- Detectors Contoured to the Shape of Vessels
- Upgrade Utilizing Existing Sources
- Accurately Measures the Most Complex Processes
- Solid Crystal or Flexible Scintillating Fill- Fluid
- Excellent Measurement Reliability due to Proprietary Filtering Technology
- Level Detection of Multiple Interfaces
- Low Maintenance / No Component Wear
- Auto-Calibration
For more information in Eastern Pennsylvania, New Jersey, Metro New York or Delaware contact:
Miller Energy by visiting https://millerenergy.com or by calling 908-755-6700 in New Jersey, or 610-363-6200 in Pennsylvania.
Industrial Refractometers Used in Process Control
Refractometer for pharmaceutical use (K-Patents). |
Process refractometers provide the analysis to quickly, reliably, and very accurately identify a sample and determine it's concentration and purity levels. They measure the refractive index and temperature of flowing liquids, and apply mathematical functions to determine the concentration of dissolved solids.
Common industrial refractometer applications are:
- Calculating beverages’ amount of sugar dissolved is water.
- In commercial food applications such as juice production or tomato processing, refractometers are used to measure degrees Brix (Tthe Brix scale relates refractive index to sugar concentration, and is a key way to maintain consistency).
- In the pharmaceutical industry, process refractometers are used to monitor and control concentration levels during supersaturation, a critical process in crystallization.
- In pulp and paper production, process refractometers for measuring dissolved solids in black and green liquor during the chemical recovery process.
For more information on industrial refractometers, contact Miller Energy by visiting https://millerenergy.com or by calling 908-755-6700 in New Jersey or 610-363-6200 in Pennsylvania.
Laboratory Flame Testing of Industrial Pressure Gauges: Wika vs. Competitor
Laboratory flame testing of industrial pressure gauges. Manufacturer Wika versus a competitor. The test is structured in (3) stages: a 10 second burn, a 30 second burn, and then a one minute burn. The Wika gauge maintains its reading, does not melt, and does not continue to burn.
https://millerenergy.com
New Jersey 908-755-6700
Pennsylvania 610-363-6200
https://millerenergy.com
New Jersey 908-755-6700
Pennsylvania 610-363-6200
Flow & Pressure Instrumentation for Biopharmaceuticals & Life Sciences
Producing biopharmaceuticals is one of the world’s most demanding manufacturing processes.
Brooks Instrument’s mass flow and pressure control technology helps maximize cell culture yields and control bioprocess costs. Their flow
and pressure controllers set global standards for reliability, repeatability and long-term stability.
Brooks Instrument mass flow controllers (MFCs) satisfy key biotechnology research and production requirements:
Brooks Instrument’s mass flow and pressure control technology helps maximize cell culture yields and control bioprocess costs. Their flow
and pressure controllers set global standards for reliability, repeatability and long-term stability.
Brooks Instrument mass flow controllers (MFCs) satisfy key biotechnology research and production requirements:
- Tight control of DO and pH during experiments and production
- NO unplanned downtime due to high cost of losing a batch or experiment
- Ability to rapidly diagnose and resolve issues with bioreactors or fermentation equipment
- Cost-effective method for adhering to regulatory requirements
- Excellent technical support and rapid response for equipment service
To read the entire Flow & Pressure Instrumentation for Biopharmaceuticals & Life Sciences guide from Brooks Instrument, download it here. Alternatively, browse the embedded document below.
What Advantages Do Displacer Transmitters Have Over Differential Pressure Level Transmitters?
Displacer Transmitter (Magnetrol) |
An example of a "tried and true" technology that was commonly used in the process automation industry is the DP (differential pressure) level transmitter. First introduced in the 1950s, DP transmitters measures the hydrostatic (head) pressure of a liquid in a tank or vessel and interprets this as level, based on the density/specific gravity of the liquid and programmed in by the user. A newer, alternative technology to DP transmitters is the displacer level transmitter, a device also based on specific gravity. While they both are dependent on specific gravity, they are significantly different in areas of installation, accuracy, and maintenance requirement.
Application/Calibration
Applying a DP transmitter or displacer level transmitter requires experience and there are many factors to be considered. Here are a few:
DP transmitters use inferential measurement to determine level measurement from the hydrostatic pressure. Despite requiring the specific gravity variable having to be programmed into the transmitter electronics, the level displacer transmitter is in contact with the process media and the level measurement is direct.
DP transmitters requires time consuming and expensive calibration/re-calibration if any of the set-up parameters change or if the same DP transmitter is used on different materials in the same tank.
Displacer transmitters only require two variables to be programmed (temperature and specific gravity), making it easier when running multiple products in the same tank.
Many displacer transmitters do not require liquid to be present for calibration. They are programmed (wet or dry) using software. A huge time and money saving over DP transmitters.
Mounting
The physical mounting of DP transmitters is limited, which can in some situations can become downright problematic. DP transmitters require (2) side-mounted entry locations on the vessel or tank, with one having to be near the bottom. As a general rule, the fewer the entry points of a tank or vessel, the better, because of leakage. Tank bottom entries all the more so.
Displacer transmitters are mounted to meet the requirements of the application and do not require a connection at the bottom of the tank.
Installation Cost
While DP transmitters have a lower unit cost, adding ancillary components such as tubing and heat tracing can quickly "level" the installation cost playing field. Furthermore, don't discount the time cost savings when setting up, calibrating and re-calibrating displacer transmitters.
Temperature Range
DP transmitters have a normal operating temperature of up to 250°F, with an upper limit of 650°F when special options are specified.
Displacer transmitter can be used up to 850°F, very helpful particularly with level measurement in a hot oil separator application.
There are many options and variants to accommodate industrial level applications. Share your level application challenges with instrumentation specialists, leveraging your own knowledge and experience with their product application expertise to develop the most effective solution.
Cashco / Valve Concepts Model 3100 Packing Material Removal and Weight Installation Instructions
Valve Concepts Model 3100 |
The Model 3100 end-of-line conservation breather vent is designed for use on atmospheric and low-pressure storage tanks where pressure and vacuum relief is required.
How it Works
Weight loaded pallets in the vent housing allow the intake of air and the escape of vapors as the tank breathes due to thermal changes and product movement in and out of the tank. The pallets open and close to permit in breathing and out breathing necessary to maintain the tank pressure within permissible limits to avoid damage to the tank.
Labels:
3100,
Cashco,
Delaware,
Eastern Pennsylvania,
New Jersey,
New York,
Tank Vent,
Valve Concepts
Paperless + Wireless Process Control Recorder
Paperless and Wireless Yokogawa GX20W |
High sampling speed of multiple inputs that can be configured to accommodate a range of input signals, along with data storage, network communications and programmable alarm outputs power up the usefulness of these instruments for monitoring and documenting process operation. Many utilize touch sensitive screens, eliminating any buttons or keys on the operator panel.
Some of the great features available on today's paperless recorders:
- Multiple channels of input
- Start/stop recording by batch, and create data files
- Ample internal memory
- Creation of template-based Excel spreadsheets
- Custom display function
- Historical data with date and time calendar search function
- Ethernet interface
- PROFIBUS-DP and EtherNet/IP protocols
- Dust and splash-proof front panel
- Front panel door lock and login function
Wireless Seals the Deal
Wireless technology is a serious contributor in the effort to improve plant efficiency, lower risk, and increase productivity. Wireless recorders are now available for monitoring virtual all process variables such as pressure, temperature, level, and flow (plus many more). The use of wireless recorders provides a compelling argument when you consider installation cost savings and convenience. Savings estimates as high as 70% are realized when compared to the cost using cables for the same application.
There are many options and variants to accommodate every conceivable process control application. Share your data acquisition and process monitoring challenges with instrumentation specialists, leveraging your own knowledge and experience with their product application expertise to develop an effective solution.
For more information on paperless recorders, contact Miller Energy by visiting https://millerenergy.com or calling 908-755-6700 in NJ or 610-363-6200 in PA.
Pressure Switches - The Stalwart of Pressure Instrumentation
Pressure switch in an explosion-proof housing. (United Electric) |
In heavy industry, pressure switches are used in virtually every power plant, refinery, chemical plant, paper mill, steel mill, or other manufacturing plant that blends ingredients.
Pressure switches are simple devices. They can be broken down to their major parts: a pressure port or connection; a sensor that moves in relationship to changing pressures; an electrical or pneumatic switch that opens or closes upon movement; and finally a housing that protect the internals of the pressure switch from the ambient conditions.
Differential pressure switch. (United Electric) |
One of the earliest and most common designs of pressure switch was the bourdon tube pressure sensor accompanied by a mercury switch. A mercury switch is a position sensitive glass bulb containing mercury that flows over, or away from, the electrical contacts. When pressure is applied, the bourdon tube attempts to straighten, and moves enough to slightly tilt the mercury switch. Many of these kind of pressure switches were sold on steam boilers, and while they became a de facto standard, they were sensitive to vibration and breakage of the mercury bulb.
NO vs. NC electrical switch contacts. |
One of the criteria of any pressure switch is the deadband or (reset pressure differential). This setting determines the amount of pressure change required to reset the switch to its normal state after it has tripped. The “differential” pressure of a pressure switch should not to be confused with differential pressure switch, which actually measures the difference in pressure between two separate pressure ports.
When selecting pressure switches you must consider the electrical requirements (volts, amps, AC or DC), the area classification (hazardous, non-hazardous, general purpose, water-tight), pressure sensing range, body materials that will be exposed to ambient contaminants, and wetted materials (parts that are exposed to the process media).
It's always a good idea to discuss your application with an expert before specifying or installing a pressure switch. You'll end up saving time and money, and ensure long, safe operation.
For more information on pressure switches, contact Miller Energy by visiting https://millerenergy.com or by calling one of these numbers: In New Jersey 908-755-6700. In Pennsylvania 610-363-6200.
Using Brooks Mass Flow Controllers with LabVIEW™
Coriolis mass flow controller Image courtesy Brooks Instrument |
Listed below are some of the more convenient communication methods to tie Brooks MFCs and LabVIEW™ software together.
Analog Signal Interface
In many situations LabVIEW™ software users also use analog to digital
I/O cards. With analog input cards, users can run their mass flow controllers utilizing a standard 0-5 volt or 4-20 mA analog signaling via LabVIEW™. This is a time-tested, traditional approach and is recommended for applications without the availability of digital control systems.
RS485 Digital Interface
Brooks Instrument mass flow devices configured with RS485 communications (must have the ‘S’ communications option) provide RS485 digital communications via a 15-pin D connector. The RS485 digital signal is passed directly to a computer running LabVIEW™ through a serial RS485 converter. Brooks models GF40, GF80 and SLA Series mass flow controllers are available with the ‘S’ communications option.
Its valuable to note that there is also a free set of VI file for use with LabVIEW from Brooks. These can be loaded directly into the LabVIEW™ application and provide the basics required to create a LabVIEW control interface using the S-Protocol digital command structure. The VI files are available for download from the Brooks Instrument website.
Another communications alternative is using Brook’s Smart DDE (Dynamic Data Exchange) software tool to create links between the LabVIEW™ application and the GF40, GF80 or SLA Series flow, control, and configuration parameters. Additionally, the user can leverage Windows applications (Excel, Word, Access) and programming languages ( C++, C#, Visual Basic) and SCADA programs from suppliers such as Allesco and Millennium Systems International. No knowledge of the mass flow device S-Protocol command structure is required. With Smart DDE, the user gets direct access to the required data fields. While not a complete turnkey option, it greatly reduces the amount of code required to communicate between LabVIEW and the mass flow controller.
DeviceNet Digital Signal Interface
Brooks models GF40, GF80 and SLA, configured for DeviceNet digital communications, can also be controlled via the LabVIEW™ application provided a National Instruments DeviceNet interface card, associated drivers, and software are used. These additional items support the development of application interfaces using LabVIEW™ software for Windows and LabVIEW™ Real-Time.
According to the National Instruments website:
National Instruments DeviceNet for Control interfaces are for applications that manage and control other DeviceNet devices on the network. These interfaces, offered in one-port versions for PCI and PXI, provide full master (scanner) functionality to DeviceNet networks. All NI DeviceNet interfaces include the NI-Industrial Communications for DeviceNet driver software, which features easy access to device data and streamlined explicit messaging. Use a real-time controller such as PXI and NI industrial controllers to create deterministic control applications with the NI LabVIEW Real-Time Module.
Share your mass flow measurement and control challenges with application experts, leveraging your own knowledge and experience with their product application expertise.
Fixed Gas Detectors
Fixed installation gas sensor / transmitters. Image courtesy 3M - Oldham |
Oldham, a 3M brand, manufactures fixed and portable hazardous gas detection and monitoring equipment for application in commercial and industrial settings. Their sensors and stations enable continuous monitoring of process or facility conditions and alert of potentially dangerous conditions. The application possibilities range through every industry.
The product line employs a number of technologies, with varied housings and form factors to accommodate any installation requirement. A wide range of gases can be detected and measured. Share your hazardous gas and flame detection monitoring challenges with process measurement specialists, leveraging your own knowledge and experience with their product application expertise to develop a safer solution for your facility.
Smart Output™ Module For Water System Monitoring
Full bore flanged and insertion style magnetic flowmeters, with Smart Output™ technology to enhance their functionality. Image courtesy McCrometer |
Magnetic flowmeters are an integral part of water system instrumentation. Their advantages for use in water systems were outlined in a previous article on how magnetic flowmeters work. McCrometer is an innovator in the design and manufacture of magnetic flowmeters for water system flow measurement. Their Smart Output™ technology is available for use with full bore flanged and insertion style flowmeters to provide the information needed for modern water system operation.
- AC or DC powered versions
- Compatible with Sensus and Itron smart water networks
- Enables networking of water meters throughout distribution system
- Queries, diagnostics, and data transfer can be scheduled or on demand
- Enables AMR (Automatic Meter Reading) and AMI (Advanced Metering Infrastructure)
The Smart Output™ function is an additional module included as part of the instrument transmitter.
More information is available from product application specialists, with whom you should share your flow measurement challenges of all types. Leverage your own process knowledge and experience with their product application expertise to develop effective solutions.
Top End Guided Wave Radar Level Transmitter
Magnetrol's model 706 embodies the best of guided wave radar level measurement. Image courtesy of Magnetrol |
Product improvements include increased signal to noise ratio, suitability for use with low dielectric media, and the ability to deliver accurate indication under foaming, flashing, or other challenging conditions. An extended probe offering enables use in measuring interface, liquified gas, even bulk solids.
The instrument is suitable for overfill applications, and does not use algorithms to infer measurements in a dead zone that may occur near the top of the probe in some other designs. The Eclipse 706 delivers true measurement right up to the process flange. Upgraded electronics allow the unit to be pre-configured prior to shipment, if requested. Additionally, the widest range of communications options is available.
For more information, share your level measurement challenges with a process measurement specialist. Leverage your own process knowledge and experience with their product application expertise to develop effective solutions.
Miller Energy Expands Capabilities With New Valve Line
The sliding gate control valve is part of the Schubert & Salzer product line. Image courtesy Schubert & Salzer. |
Schubert & Salzer specializes in precise control and stop valves for industrial fluid processing operations.
- Sliding gate valves
- Ball Sector Valves
- Segment disc valves and segment disc orifices
- Seat valves
- Three-way valves
- Sanitary valves
- Pinch Valves
- Manual valves
- Positioners & controllers
- Accessories to complement all products
With the expansion of its already wide range of common and specialized valve technologies, Miller Energy further solidifies its position as the go-to source for solutions to fluid process control challenges. Contact the Pennsylvania office for detailed product information. Share your challenges and leverage your process knowledge and experience with their product application expertise to develop effective solutions.
Magnetic Level Indicators
Configurations of magnetic level gauges Image courtesy Orion/Magnetrol |
- Direct or indirect measurement of level
- Level measurement accuracy and reliability
- Tank shape, regular or irregular
- Media compatibility with measurement device
- Requirements for maintenance or calibration
- Compatibility with process temperature and pressure range
- Local display and visibility
- Level indication signal type and transmission
- Level alarm switches or other indicators
- Continuous level measurement
- Operable without electric power
- Direct visual tank fluid level indication, regardless of tank shape or profile.
- Wide range of operating temperature and pressure
- Breakage resistant construction
- Range of construction materials available to accommodate corrosive media
- Measuring indicators, switches, and transmitters mounted externally, without contacting the medium being measured.
- Low maintenance operation.
- Readable level indication from greater distance than glass sight gauges.
- Applicable to large fluid level ranges with a single instrument.
Electronic to Pneumatic Converter
Component schematic using electronic controller and pneumatic control valve Image courtesy of Yokogawa |
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.
Sometimes the Simple Solution Is the Best
This metal tube variable area flow meter is reliable, accurate, and requires little maintenance Photo courtesy Brooks Instrument |
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.
Heat Processing of Industrial Fluids
Steam produced by gas fired industrial boilers is a commonly applied means of delivering heat energy |
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 system’s 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. Selecting and properly applying the best suited controls, instruments and equipment is a key element of successful process operation. Share your challenges with application experts, combining your own process knowledge and experience with their product expertise to develop effective solutions.
Subscribe to:
Posts (Atom)