Showing posts with label Wyoming. Show all posts
Showing posts with label Wyoming. Show all posts

Wednesday, January 10, 2018

Steam Trap For Heavily Contaminated Steam

cast iron float steam trap
The Float Trap series is available in carbon or stainless steel.
Image courtesy Spirax Sarco
Industrial process gear and equipment manufacturers are always tweaking designs, adding features, and creating new product variants in response to the challenges presented by the immeasurably broad range of application and operation scenarios for their products. Spirax Sarco is a globally recognized leader in the design and manufacture of steam system specialties, and has created a rugged steam trap to accommodate some tough challenges.

The company's FTC23 and FTS23 Float Trap products are ball float steam traps suitable for use with saturated and superheated steam. The units can be utilized on process equipment and for drainage of temperature controlled systems. These traps are specifically targeted at applications involving steam that may be carrying solids or incondensable gasses. Solids, if not purged from the system, can accumulate and foul the internal trap mechanism, leading to failure.

The company indicates that the main design feature is a self-cleaning float closing mechanism which maintains safe operation even in the presence of severe contamination. The positioning of the valve and seat also promote the discharge of the condensate, along with entrained contaminants. There is even a manual lever on the exterior of the trap that allows an operator to force the full opening of the valve, regardless of whether condensate is present. This operation facilitates fast removal of contaminants and maintains optimum performance.

The two models differ in their construction materials, with one having a carbon steel body, the other a stainless steel body. Internals are stainless steel on both units.

Share your challenges with the steam system specialists, leveraging your own knowledge and experience with their product application expertise.


Friday, January 5, 2018

Piston Isolation Valves For Steam and Condensate

carbon steel or stainless steel piston valve for steam or condensate
Simple and reliable piston isolation valve is well suited
for steam and condensate applications.
Image courtesy Spirax Sarco
Piston valves are serviceable and reliable valves that are well applied to isolation use in steam and condensate systems. Recently, Spirax Sarco, globally recognized manfacturer of steam system componentry, introduced their PV4 and PV6 lines of piston isolation valves targeted at steam and condensate applications.

The new valves are available with carbon steel or stainless steel bodies, with the internals of both being stainless steel. Screwed, socket weld and butt weld connections are available in 1/2" through 2" sizes. The operation is unidirectional, so installation must have the system flow according to the arrow on the body. The only other installation restriction is that the handwheel should be above the valve body.

Accommodated pressure and temperature ranges for the PV4 and PV6 will be suitable for a broad range of steam and condensate applications. Share your steam system challenges of all types with application specialists. Leverage your own knowledge and experience with their product application expertise to develop effective solutions.


Wednesday, December 13, 2017

Process Tuning

sliding gate industrial process control valve
This sliding gate industrial control valve could operate
under the command of a tuned process control loop.
Image courtesy Schubert & Salzer
Controller tuning is a process whereby a controlling device in a process has a response characterized to the needs of maintaining a process condition within certain limits under a range of varying disturbances to the process. Established guidelines for automation standards exist so that every process control operator can experience the same standard of safety and maintenance in a way universally understandable. The International Society of Automation (ISA) promotes different tuning standards based on the particulars of the control process, such as temperature or liquid level control.

Liquid-level control loops are usually considered non-self-regulating processes. They require external moderation to remain uniform and for errors to either be mitigated or corrected. General rules which exist for adjusting and tuning loops for self-regulating process, such as temperature control, are often inapplicable to liquid level loops, making liquid level control loops somewhat unique in their tuning.

In order to address the counter intuitive nature of these process loops, start with a model of the loop’s ideal functionality. This can serve as a reference. After doing so, incorporate potential variables into the ideal loop and evaluate their impact on the model process. Checking equipment, then modeling the process dynamics, allows engineers to observe the manner in which the process reacts in relation to the target or goal performance.

Whereas other loops can be tuned via trial and error, liquid-level control loops should not be due to the nature of their reactions to controller input being different than that of other processes. Instead, the parameters for the control loop need to be carefully engineered, rather than specifically tuned. Liquid level loops are integrating processes, rather than self-regulating. A self-regulating process will, with no disturbances to the variables, reach an equilibrium at which the process value remains constant. Consider a non-self-regulating liquid level control loop where the fill valve is open. No equilibrium point will be achieved, just overflow. The distinction between the two types is key to understanding why tuning liquid level loops is a different process than self-regulating control loops.

Temperature and thermal loops, depending upon the process dynamics, present varying degrees of tuning challenge. PID temperature controllers are employed to adjust the heat input to a process to affect a change in, or maintenance of, a process temperature setpoint. Without proper tuning, the controller output and the resulting process performance can oscillate or be slow to respond, with a negative impact on process performance or yield. Many PID controllers have an auto-tune feature, some of which are more effective than others. The best results achievable by PID controller tuning are accomplished by defining a setpoint prior to the auto-tune process and starting the tuning procedure from a stable process condition. Tuning the controller in the same process environment in which it will operate can also be very helpful.

Share your process measurement and control challenges with experienced application specialists, combining your own knowledge and experience with their product application expertise to develop effective solutions.

Thursday, December 7, 2017

Compressed Air as a Motive Force

coalescing filters for compressed air
Coalescing filters are common components of a compressed
air system.
Image courtesy SPX Pneumatic Products
Compressed air is utilized throughout every industry and many commercial settings. While primarily used as a motive force, compressed air serves as a utility in many applications in the oil and gas, chemical and petrochemical, nuclear power, food, pharmaceutical, and automotive industries. The presence and use of compressed air across multiple industries is so essential, its importance is comparable to utilities like electricity, gas, and water.

In the control of fluid processes, compresses air facilitates operation and control of valves and other instruments. Dry air, with a sufficiently depressed dew point, can ensure process materials and equipment stay free of moisture and its associated impediments to smooth operation. The use of compressed air as either a motive force or a utility imparts minimum requirements on its quality or constituents. Confounding substances, such as particulates, water, and oil, may be entrained or contained in a compressed air stream. Various methods of filtration and moisture removal may be necessary to condition or process the compressed air in order to deliver consistent quality.

The advantages of using compressed air as a motive force in industrial settings are more numerous than appropriate for listing here, but consider that tools driven by compressed air can be more compact, lower weight and less prone to overheating than electrically driven tools. Air driven devices tend to have reduced parts count and require little maintenance, whether tools, valve actuators, pistons, or other machines. Compressed air driven devices can be fashioned to amplify the power of an electrical signal, enabling a simpler means of powering some types of loads. Compressed air, by its nature, presents no electrical hazards to the workplace.

Whenever air driven devices are utilized, attention must be given to compressed air production. The pressure, maximum flow rate demand, and compressed air quality must meet the process or operation requirements. Share your compressed air system challenges with specialists, leveraging your own knowledge and experience with their product application expertise to develop effective solutions.

Tuesday, November 28, 2017

Pipeline Cyber Security

binary stream representing industrial process control network data transfer and cyber security threat
Cybersecurity is a process control challenge that consistently evolves as new technologies come into use and new threats emerge. Since process control methods are constantly developing, the protective measures need to match the rate of change to ensure adequate levels of protection are in place. Pipelines used in the oil and gas industry, as well as in the transportation of a multitude of liquid and gaseous products, account for more than 2.3 million miles of process piping in the United States.  Natural gas pipelines are commonly monitored and controlled by, for example, programmable logic controllers or other microprocessor and communications based systems, responsible for flow regulation and various process conditions. Because of the prevalence of these systems, they are a target of increasing attacks, on both PLCs and other SCADA related devices, such as compressors, remote terminal units, communication networks, and other critical process infrastructure elements.

While developments in technology have provided operating advantages and improvements to the process industries, the more complex and advanced the systems may also increase the exposure to malicious penetration and mischief by unauthorized parties (hackers). Because of this, diligence by industry professionals, while always a strong component of protecting against outside threats, has been augmented via new guidelines meant to better prepare all process operators against more coordinated cyber-attacks.

Basic preventative measures, such as a firewall, are no longer a sufficient bulwark against the increasing threats. Instead, the entire process must be evaluated and monitored so that each individual piece of the network is understood fully. If a part of the system starts behaving in an abnormal way, then an understanding of what that specific PLC or component affects must be immediately known. The most effective protective programs will be able to function without needing any downtime, and will also be able to learn the network easily. Whenever the defense program gets triggered, it needs to not only provide a general alert to the process operator, but must also be able to provide context so that the previous knowledge of how the system works can be applied to mitigate the current problem.

Currently, the oil and gas industry has transitioned to what is being termed a ‘holistic’ approach to cyber defense. In order for the best security possible to be employed, the human element of process control must function in tandem with the autonomous programs. The human component of process operation, where it exists, can be unpredictable and present vulnerabilities that may not be known or anticipated. Everything must be considered.

Industrial process operation involves many areas of risk, with cyber attack being just one. The right kind of planning and response to risk can mitigate the potential impact. Security efforts, technology, and knowledge must keep pace with threats which emerge to process pipeline security. Mountain States Engineering and Controls participates in the oil and gas industry throughout the western U.S.

Thursday, November 16, 2017

Forced Draft Cooling Tower With 20 Year Warranty

corrosion resistant HDPE cooling tower rated 50 tons with forced draft
Forced draft corrosion resistant cooling tower
with forced draft, rated 50 tons. Pioneer series.
Image courtesy Delta Cooling Towers
Delta Cooling Towers specializes in the design and construction of corrosion resistant cooling towers and similar equipment. Much of the tower construction is HDPE or other non-metallic material, enabling the company to offer a 20 year warranty on their equipment.

Cooling towers are employed worldwide in HVAC applications and process fluid cooling. In addition to their industry leading corrosion resistance, Delta Cooling Towers also offers anti-microbial protection which combats the growth of microbes responsible for Legionnaires Disease and other respiratory ailments. The various product lines cover heat transfer capacities to accommodate any installation.

There is a lexicon employed in the description of cooling tower performance and operation. Some commonly used terms, along with their meaning, is provided below. The terms and their meanings is pulled from the owner's manual provided by Delta Cooling Towers for their Pioneer series of forced draft cooling towers.

Share your process and HVAC cooling challenges with application experts, leveraging your own knowledge and experience with their product application expertise to develop an effective solution.

Cooling Tower Terms and Definitions

  • BTU - A BTU is the heat energy required to raise the temperature of one pound of water one degree Fahrenheit in the range from 32° F. to 212° F.
  • Cooling Range - The difference in temperature between the hot water entering the tower and the cold water leaving the tower is the cooling range.
  • Approach - The difference between the temperature of the cold water leaving the tower and the wet-bulb temperature of the air is known as the approach. The approach fixes the operating temperature of the tower and is a most important parameter in determining both tower size and cost.
  • Drift - The water entrained in the air flow and discharged to the atmosphere. Drift loss does not include water lost by evaporation. Proper tower design and operation can minimize drift loss.
  • Heat Load - The amount of heat to be removed from the circulating water through the tower. Heat load is equal to water circulation rate (gpm) times the cooling range times 500 and is expressed in BTU/hr. Heat load is also an important parameter in determining tower size and cost.
  • Ton - An evaporative cooling ton is 15,000 BTU's per hour.
  • Wet-Bulb Temperature - The lowest temperature that water theoretically can reach by evaporation. Wet-Bulb Temperature is an extremely important parameter in tower selection and design and should be measured by a psychrometer.
  • Pumping Head - The pressure required to pump the water from the tower basin, through the entire system and return to the top of the tower.
  • Make-Up - The amount of water required to replace normal losses caused by bleedoff, drift, and evaporation.
  • Bleed Off (Blowdown) - The circulating water in the tower which is discharged to waste to help keep the dissolved solids concentrating in the water below a maximum allowable limit. As a result of evaporation, dissolved solids concentration will continually increase unless reduced by bleed off.

Friday, November 10, 2017

Hydrostatic Pressure Liquid Level Measurement

differential pressure tank level indicator
Tank mounted differential pressure transmitter
measures hydrostatic pressure to derive liquid level
Image courtesy King-Gage
Liquid level can be inferred by accurately measuring the pressure produced by the height of a fluid column and knowing the density of the liquid measured. The measurement is comparative in nature, referencing some external pressure as a zero point. The zero point can be the surrounding atmospheric pressure, tank pressure, or the pressure exerted by another column of liquid contained elsewhere.

There are uncountable application scenarios, each with its own set of special conditions. Proper instrument selection, installation and calibration are essential to generating reliable and accurate results.

The King-Gage TeleSensor™ liquid level transmitters are specially designed to provide level measurements across a wide range of liquids using a force balance principle in a pneumatic sensor. Sensor output can be either a pneumatic signal or 4-20 mA. The pneumatic force balance arrangement provides immunity to long term drift, hysteresis and temperature changes. A diaphragm isolates the sensor from the process liquid. Mounting is compatible with 2", 3", or 4" class 150 ANSI flanges. Various options for diaphragm and flange materials are available to accommodate a range of process media.

More detail is provided in the document included below, along with application examples. Contact product specialists to share your application challenges and get effective solutions.

Thursday, November 2, 2017

Steam Condensate Return Stations

duplex condensate return station
Duplex condensate return station
Image courtesy Roth Pump
Closed steam systems produce condensate, a dense source of heat. By design, the delivery of heat in a steam system is almost entirely accomplished using the heat of vaporization, with any sensible heat transfer probably being more coincidental than intentional. Condensate will contain most of the sensible heat that was added to the feedwater to get it to the boiling temperature. Conserving that sensible heat through a reuse of the hot condensate is a huge energy saving step. The condensate must be collected and returned to the boiler in a effective manner.

A condensate return station is a common means of moving condensate back to the boiler. It will generally consist of a collection vessel for the liquid condensate and one or more pumps to provide the motive force to move the liquid along its return path. Reliability is a key factor for these systems, since it is conceivable that they may need to perform on a continuous basis for years. A duplex pump arrangement can provide some backup, as well as extra capacity for accommodating large inlet flow. This is an installation where investing in rugged hardware can pay dividends in reduced maintenance burden and trouble free performance for the long term.

Roth Pump Company has been designing and manufacturing condensate return stations and other steam system related components for many years. Their experience and expertise are part of each and every system that leaves their factory. By incorporating low RPM motors, heavy duty pumps, and other features into a compact form factor, the company is able to offer a number of systems that meet a wide range of applications and deliver solid long term performance.

Share your steam system and condensate return requirements and challenges with application experts, leveraging your own experience and knowledge with their product application expertise.


Thursday, October 26, 2017

When to Use a Globe Valve for Fluid Process Control

cast iron globe valves
Cast iron globe valves are utilized extensively in steam,
HVAC, and other commercial and industrial applications
Image courtesy of Crane Co.
Industrial process control often involves the regulation of fluid flow. There are almost uncountable types and variants of flow control valves, each with a particular set of attributes that can make it the advantageous choice an application.

When the process calls for controlling flow over a range of possible values, known as throttling, a globe valve may be a good candidate for the application.

Globe valves are characterized by the change in direction of fluid flow as it passes through the valve and around the plug positioned in an opening through which fluid must pass. The plug is connected to a stem extending to the exterior of the valve body through the bonnet. Movement of the stem will reposition the plug in relation to the opening, providing a successively larger or smaller opening area through which fluid can pass.

Globe valves are available in tee, angle, and wye configurations, as well as an enormous range of special configurations to suit specific applications.
simplified globe valve diagram
Simplified globe valve diagram
Image courtesy Wikipedia


What are some potential advantages of globe valves?
  • Good throttling and shutoff capability
  • Comparatively easy maintenance
  • Comparatively short travel of plug from open to closed position
  • Seats can usually be resurfaced when worn
What are some limiting factors for globe valves?
  • Higher valve pressure drop than some other designs
  • No straight through fluid path
  • Potentially higher actuator torque requirements than other valve types
  • Seal area is unprotected from exposure to process fluid flow
When flow throttling capability is the overriding concern for an application, a globe valve is a good candidate for consideration. Share your flow control challenges with valve and automation specialists. Combining your process knowledge and experience with their product application expertise will produce effective solutions.

Friday, October 20, 2017

Wet Bulb Temperature and Cooling Tower Performance

corrosion resistant cooling tower induced draft type
Corrosion resistant evaporative cooling tower
Image courtesy Delta Cooling Towers, Inc.
Evaporative cooling towers enable many buildings across the globe to enjoy moderate interior temperatures. They serve as the final heat transfer step that moves heat from the building interior to the surrounding environment. In addition to their extensive application throughout large residential, commercial and industrial HVAC systems, their are numerous process cooling applications that employ evaporative cooling towers as an effective means of heat rejection.

Delta Cooling Towers, Inc. is a globally recognized manufacturer of corrosion resistant cooling towers, air strippers and tanks fabricated of HDPE to provide extended life service. The company posted an article entitled "Understanding Wet Bulb Temperatures And How It Affects Cooling Tower Performance". The original post is on this page of the company website, and all credit for the article goes to them. We share it below also, slightly edited for format on this forum.  From the article...

A cooling tower primarily uses latent heat of vaporization (evaporation) to cool process water. Minor additional cooling is provided by the air because of its temperature increase. Cooling tower selection and performance is based on water flow rate, water inlet temperature, water outlet temperature and ambient wet bulb temperature. Ambient wet bulb temperature and its affect on performance is the subject of this article. Ambient wet bulb temperature is a condition measured by a device called a psychrometer. A psychrometer places a thin film of water on the bulb of thermometer that is twirled in the air. After about a minute, the thermometer will show a reduced temperature. The low point when no additional twirling reduces the temperature is called the wet bulb temperature. The measured wet bulb temperature is a function of relative humidity and ambient air temperature. Wet bulb temperature essentially measures how much water vapor the atmosphere can hold at current weather conditions. A lower wet bulb temperature means the air is drier and can hold more water vapor than it can at a higher wet bulb temperature. For example:
Since cooling tower cells cool water by evaporation, the wet bulb temperature is the critical design variable. An evaporative cooling tower can generally provide cooling water 5° - 7° higher above the current ambient wet bulb condition. That means that if the wet bulb temperature is 78°F, then the cooling tower will most likely provide cooling water between 83° - 85°F, no lower. The same tower cell, on a day when the wet bulb temperature is 68°F, is likely to provide 74° - 76°F cooling water. When selecting a cooling tower cell, the highest or the design wet bulb temperature your geographical area will encounter must be used. Highest wet bulb temperatures occur during the summer, when air temperatures and humidity is highest. For example, in Indianapolis, Indiana, the design wet bulb temperature is 78°F. Historically Indianapolis can expect less than one hour per year that the conditions exceed a 78°F wet bulb. Typically, 6,000 hours a year will have a wet bulb of 60°F or lower meaning that a cooling tower cell designed for a 78°F wet bulb will be able to make 65-67°F water for 6,000 hours per year nearly 70% of the year. Most cooling towers are capacity rated at a "standard" wet bulb temperature of 78°F. That means on the days when the wet bulb temperature is 78°F, the tower will produce its stated capacity. In other words, a tower rated to produce 135 tons of cooling will produce 135 tons of cooling at a 78°F wet bulb temperature. At a higher wet bulb temperature, the tower cell capacity to produce colder water decreases. Every location has a unique design (worst case) wet bulb temperature that is published by organizations such as ASHRAE and can be obtained easily.

What does it mean when your cooling tower water temperature is higher than the normal 5-7°F above the current wet bulb temperature?

  1. Your cooling load may be larger than the rated capacity of your cooling tower.
  2. Your cooling tower may have lost efficiency
  • Due to scale build up on the tower heat exchange surfaces.
  • Due to loss of air flow across the heat exchange surfaces.
  • Due to improper water flow from clogged nozzles or pump performance
What can you do to improve your tower performance? 

  • Add tower cell capacity
  • Check for the efficiency losses described above
  • Replace the heat exchange surfaces with new clean fill
  • Check for proper airflow
  • Check the water flow is at design
  • Check that nozzles are not clogged or broken


Cooling tower performance is tied to ambient wet bulb conditions. Higher wet bulb temperatures occur in the summer when higher ambient and relative humidity occurs. Initial system design and proper system maintenance is critical to be certain your cooling tower is providing desired cooling.

For more information, or to discuss your own heat transfer challenges, contact a product application specialist. Combine your own knowledge and experience with their application expertise to develop an effective solution.

Wednesday, October 4, 2017

Refinery Explosion Analysis and Animated Video Reenactment



Industrial accidents range in severity and impact from minuscule to catastrophic. As operators, owners, or technicians involved with industrial operations, we all have a degree of moral, ethical, and legal responsibility to conduct our work in a manner that does not unduly endanger personnel, property, or the environment. Maintaining a diligent safety stance can be helped by reviewing industrial accidents at other facilities. There is much to learn from these unfortunate events, even when they happen in an industry that may seem somewhat removed from your own.

The U.S. Chemical Safety Board, or CSB, is an independent federal agency that investigates industrial chemical accidents. The video illustrates their animated reenactment and causal analysis of an explosion that occurred at a refinery in Louisiana in 2016. Check out the video and sharpen your senses to evaluate potential trouble spots in your own operation. Share any questions or concerns with process control specialists and reduce the level of risk at your facility.

Thursday, September 28, 2017

Breathing Air Purifiers

breathable air purifier system
A breathing air purifier unit processes
compressed air, making it suitable for respirators.
Image courtesy SPX Pneumatic Products
There are many instances throughout science and industry where tasks must be performed by human operators in environments without breathable air. In many of those cases, it is necessary to provide a positively pressurized enclosed space around the operator's face to isolate the breathing passages from potentially harmful vapors, dust, or pathogens in the work area.

Applications in the petrochemical industry, as well as asbestos abatement, paint and coatings, tank cleaning and more have specific jurisdictional requirements for the provision of breathing apparatus for worker protection. A compressed air source is processed as it passes through a purifier which imposes a six stage filtration process on the compressed air inlet prior to supplying the breathable air to safety hoods or masks.

  • Removal of solid and liquid particles or droplets greater than 1.0 micron.
  • Oil and liquid aerosol removal down to 0.1 micron.
  • Water vapor removal
  • Reduction of carbon monoxide level
  • Second particulate filtration stage to 1.0 micron
  • Activated carbon removes trace odors, oil vapor, and other components
Analyzing and monitoring the outlet air quality from the purifier unit is a good practice, to assure that target levels of oxygen, carbon monoxide, moisture, and carbon dioxide are maintained. OSHA and other jurisdictional bodies specify allowable levels for certain potentially harmful gases. The quality of the inlet air should be carefully assessed and protected during operation, since it is a primary determinant of the outlet air quality.

Share your process requirements with a pneumatic system specialist, combining your own knowledge and experience with their product application expertise to develop an effective solution.

Wednesday, September 20, 2017

Trunnion vs. Floating Ball Valves

trunnion mount ball valve for industrial pipeline use
Trunnion mount ball valves have upper and lower support
points for the ball.
Image courtesy International Standard Valve, Inc.
The design, construction, and function of a ball valve is generally well understood in the industrial fluid processing arena. Ball valves provide reliable quarter turn operation, compact form factor, and tight shutoff capability, making the ball valve a preferred choice for many applications. Some ball valves also provide shutoff of fluid flow in either direction. A primary valve trim design feature permits grouping of the many variants of industrial ball valves into two categories, distinguished solely by the way in which the ball is mounted in the body.

Floating ball valves use the seats and body to hold the ball in place within the fluid flow path, with the force of directional flow pushing the ball against the downstream seats to produce a tight shutoff seal. Many floating ball valves are capable of flow shutoff in either direction. The ball is rotated by a shaft connected at the top which extends through the pressure enclosure of the valve for connection to a handle or automated actuator. The floating nature of the ball limits the applicability of this design to smaller valve sizes and lower pressures. A some point, the fluid pressure exerted on the ball surface can exceed the ability of the seats to hold the ball effectively in place.

Trunnion mount ball valves employ the stem shaft and, you guessed it, a trunnion to rigidly position the ball within the body. The shaft and trunnion, connected to the top and bottom of the ball, establish a vertical axis of rotation for the ball and prevent it from shifting in response to flow pressure. The trunnion is a pin that protrudes from the bottom side of the ball. It sits within a bearing shape, generally cylindrical, in the base of the body.

Because of their structural design, trunnion mount ball valves are suitable for all pressure ranges and sizes.They are used by many manufacturers as a basis of design for their severe service ball valve offerings. A trunnion mount ball valve can also be advantageous for applications employing valve automation. Since the ball is not held in place by a tight fitting seal arrangement, operating torque tends to be lower for comparably sized trunnion mount valves, when compared to floating ball valves.

On page 3 of the brochure included below, the exploded view of a trunnion ball valve shows the location of the trunnion assembly.

Whatever your valve application challenge, share it with an industrial valve expert. Leverage your own process knowledge and experience with their product application expertise to develop an effective solution.


Thursday, September 14, 2017

Pressure Measurement Using Isolation Ring



The D81 Isolation Ring from Winters Instrument provides a solution for measuring system pressure in processes involving fluids with potential to clog or damage sensors and impulse lines. The isolation ring has a hollow elastomer that is located between two flanges. A fitting on the elastomer section allows for connection of a gauge or transmitter without disturbing the process fluid. Pressure in the piping system is mirrored by pressure within the hollow portion of the isolation ring, measured by the connected instrument. The instrument does not come in contact with the process fluid, nor are there any small diameter impulse lines to foul or clog. Applications in mining, water treatment, pulp and paper abound. Any challenging fluid is a good candidate for application consideration. Models are available up to 48" line size, with wafer, flanged, or threaded connections.

Share your fluid process measurement requirements with application specialists, combining your own knowledge and experience with their product application expertise to develop effective solutions.



Wednesday, August 23, 2017

Cooling Towers: Operating Principles and Systems

evaporative cooling tower made of HDPE plastic
Example of evaporative cooling tower, fabricated
from HDPE plastic to resist corrosion.
Image courtesy Delta Cooling Towers
The huge, perfectly shaped cylindrical towers stand tall amidst a landscape, with vapor billowing from their spherical, open tops into the blue sky. Such an image usually provokes a thought related to nuclear power or a mysterious energy inaccessible to the millions of people who drive by power plants every day. In reality, cooling towers – whether the hyperboloid structures most often associated with the aforementioned nuclear power plants or their less elegantly shaped cousins – are essential, process oriented tools that serve as the final step in removing heat from a process or facility. The cooling towers at power plants serve as both an adjuster of a control variable essential to the process and also as a fascinating component of the process behind power creation. The importance and applicability of cooling towers is extensive, making them fundamentally useful for industrial operations in power generation, oil refining, petrochemical plants, commercial/industrial HVAC, and process cooling.

In principle, an evaporative cooling tower involves the movement of a fluid, usually water with some added chemicals, through a series of parts or sections to eventually result in the reduction of its heat content and temperature. Liquid heated by the process operation is pumped through pipes to reach the tower, and then gets sprayed through nozzles or other distribution means onto the ‘fill’ of the tower, reducing the velocity of the liquid to increase the fluid dwell time in the fill area. The fill area is designed to maximize the liquid surface area, increasing contact between water and air. Electric motor driven fans force air into the tower and across the fill area. As air passes across the liquid surface, a portion of the water evaporates, transferring heat from the water to the air and reducing in the water temperature. The cooled water is then collected and pumped back to the process-related equipment allowing for the cycle to repeat. The process and associated dispersion of heat allows for the cooling tower to be classified as a heat rejection device, transferring waste heat from the process or operation to the atmosphere.

Evaporative cooling towers rely on outdoor air conditions being such that evaporation will occur at a rate sufficient to transfer the excess heat contained in the water solution. Analysis of the range of outdoor air conditions at the installation site is necessary to assure proper operation of the cooling tower throughout the year. Evaporative cooling towers are of an open loop design, with the fluid exposed to air.

A closed loop cooling tower, sometimes referred to as a fluid cooler, does not directly expose the heat transfer fluid to the air. The heat exchanger can take many forms, but a finned coil is common. A closed loop system will generally be less efficient that an open loop design because only sensible heat is recovered from the fluid in the closed loop system. A closed loop fluid cooler can be advantageous for smaller heat loads, or in facilities without sufficient technical staff to monitor or maintain operation of an evaporative cooling tower.

Thanks to their range of applications, cooling towers vary in size from the monolithic structures utilized by power plants to small rooftop units. Removing the heat from the water used in cooling systems allows for the recycling of the heat transfer fluid back to the process or equipment that is generating heat. This cycle of heat transfer enables heat generating processes to remain stable and secure. The cooling provided by an evaporative tower allows for the amount of supply water to be vastly lower than the amount which would be otherwise needed. No matter whether the cooling tower is small or large, the components of the tower must function as an integrated system to ensure both adequate performance and longevity. Understanding elements which drive performance - variable flow capability, potential HVAC ‘free cooling’, the splash type fill versus film type fill, drift eliminators, nozzles, fans, and driveshaft characteristics - is essential to the success of the cooling tower and its use in both industrial and commercial settings.

Design or selection of an evaporative cooling tower is an involved process, requiring examination and analysis of many facets. Share your heat transfer requirements and challenges with cooling tower specialists, combining your own facilities and process knowledge and experience with their application expertise to develop an effective solution.`

Friday, August 18, 2017

Thermodynamic Steam Traps

cutaway view thermodynamic steam trap
Cutaway view of disc type thermodynamic steam trap
Image courtesy of Spirax Sarco
Condensate return is an essential operation in any closed loop steam system. Steam that has lost its latent heat will collect in the piping system as hot liquid water (condensate). This liquid needs to be separated from the steam and returned to the boiler feedwater equipment without letting steam escape in the process.

Various items of steam utilization equipment and processes will result in condensate formation at different rates. The device that collects and discharges condensate to the return portion of the system is called a steam trap. There are numerous physical principals and technologies employed throughout the range of available steam trap types. Each has application limitations and strengths making them more or less suitable for a particular installation.

A thermodynamic steam trap relies on the energy provided by the condensate to move a disc which controls the flow of the condensate into the return system. The disc is the only moving part in the device. Condensate flows through a port to a chamber on the underside of the disc, lifting the disc and directing the flow to the return system or drain. Eventually, the fluid flowing into the chamber will reach a point where some of the condensate flashes to steam. A portion of this steam flows through a channel into the space above the disc, called the control chamber. The increase in pressure in the control chamber due to the steam influx pushes downward on the disc, seating it in a closed position. The trap, with the disc seated, remains in the closed position until the flash steam in the control chamber cools and condenses. Then the disc can be opened again by the inflow of condensate.

The thermodynamic disc trap is:

  • Easy to install
  • Compact
  • Resistant to damage from freezing
The single trap can cover a wide range of system pressure, and the simple construction translates into low initial cost. Properly matching any steam trap to its application is important. Share your condensate return and steam system challenges with specialists, combining your knowledge and experience with their product application expertise to develop effective solutions.



Tuesday, August 8, 2017

Orifice Plate - Primary Flow Element

orifice plate drawing
Orifice plates are simple in appearance, but exhibit
precision machining.
Image courtesy of Fabrotech Industries
An orifice plate, at its simplest, is a plate with a machined hole in it. Carefully control the size and shape of the hole, mount the plate in a fluid flow path, measure the difference in fluid pressure between the two sides of the plate, and you have a simple flow measurement setup. The primary flow element is the differential pressure across the orifice. It is the measurement from which flow rate is inferred. The differential pressure is proportional to the square of the flow rate.

An orifice plate is often mounted in a customized holder or flange union that allows removal and inspection of the plate. A holding device also facilitates replacement of a worn orifice plate or insertion of one with a different size orifice to accommodate a change in the process. While the device appears simple, much care is applied to the design and manufacture of orifice plates. The flow data obtained using an orifice plate and differential pressure depend upon well recognized characteristics of the machined opening, plate thickness, and more. With the pressure drop characteristics of the orifice fixed and known, the measuring precision for differential pressure becomes a determining factor in the accuracy of the flow measurement.

There are standards for the dimensional precision of orifice plates that address:
  • Circularity of the bore
  • Flatness
  • Parallelism of the faces
  • Edge sharpness
  • Surface condition
Orifice plates can be effectively "reshaped" by corrosion or by material deposits that may accumulate from the measured fluid. Any distortion of the plate surface or opening has the potential to induce measurable error. This being the case, flow measurement using an orifice plate is best applied with clean fluids.

Certain aspects of the mounting of the orifice plate may also have an impact on its adherence to the calibrated data for the device. Upstream and downstream pipe sections, concentric location of the orifice in the pipe, and location of the pressure measurement taps must be considered.

Properly done, an orifice plate and differential pressure flow measurement setup provides accurate and stable performance. Share your flow measurement challenges of all types with a specialist, combining your own process knowledge and experience with their product application expertise to develop an effective solution.

Thursday, August 3, 2017

Thermocompressor Breathes New Life into Low Pressure Waste Steam

steam thermocompressor
Steam Jet Thermocompressor from Spirax Sarco
mixes high pressure and low pressure steam supplies
Energy conservation and energy efficiency have contributed very large cost savings to many industrial and commercial operations over the past two decades. Projects with modest payback periods quickly begin their contributions directly to the bottom line of the balance sheet. In many instances, incorporating energy conservation and efficiency measures also improves the overall functioning of the consuming systems and equipment. In order to save energy, it is generally necessary to exercise better control over equipment or system operation by gathering more information about the current operating state. This additional information, gathered through measurement instrumentation, often finds use in other ways that improve productivity and performance.

Steam is utilized throughout many industries as a means of transferring heat, as well as a motive force. Much energy is consumed in the production of steam, so incorporating ways of recovering or utilizing the heat energy remaining in waste steam is a positive step in conservation.

A thermocompressor is a type of ejector that mixes high pressure steam with a lower pressure steam flow, creating a usable discharge steam source and conserving the latent heat remaining in the low pressure steam. The device is compact and simple, with no moving parts or special maintenance
thermocompressor labelled schematic
Schematic of basic thermocompressor, showing suction
inlet at the bottom and high pressure steam nozzle.
Image courtesy of Spirax Sarco
requirements. Two general varieties are available. The fixed nozzle style is intended for applications with minimal variation in the supply and condition of the suction steam (the low pressure steam). Some control is achievable through the regulation of the high pressure steam flow with an external control valve. A second style provides a means of regulating the cross sectional area through which the high pressure steam flows in the nozzle. This style is best applied when specific discharge flow or pressure is required, or there is significant variation in the inlet steam conditions.

Share all your steam system challenges with a steam system application specialist. Combine your own process and facilities knowledge and experience with their product application expertise to develop effective solutions.


Thursday, July 27, 2017

Valve Positioners

industrial valve actuator with positioner
Valve positioner installed on pneumatic actuator
Courtesy Crane ChemPharma Energy
Valve positioners can provide process operators with a precise degree of valve position control across the valve movement range, as well as information about valve position. A relationship exists between applied pneumatic signal pressure and the position of the valve trim. The relationship between the two elements is dependent upon the valve actuator and the force of the return spring reacting to the signal pressure. In a perfect world, the spring and pneumatic forces would reach equilibrium and the valve would return to the same position in response to an applied signal pressure. There are other forces, however, which can act upon the mechanism, meaning the expected relationship between the original two elements of pressure and position may be offset. For example, the packing of the valve stem may result in friction, or the reactive force from a valve plug resulting from differential pressure across the area of the plug may be another.

While these elements may seem minor, and in some cases they are, process control is about reducing error and delivering a desired or planned output. Inclusion of a positioner in the valve assembly can ensure that the valve will be set in accordance with the controller commands.

Each positioner functions as a self-contained small scale control system. The first variable in the positioning process is the current valve position, read by a pickup device incorporated in the positioner. A signal which is sent to the positioner from the control system, indicating the desired degree of opening, is used as the setpoint. The controller section of the positioner compares the current valve position to the setpoint and generates a signal to the valve actuator as the output of the positioning process. The process controller delivers a signal to the valve, and then the positioner takes that signal and supplies air pressure required to accomplish the needed adjustment of the stem position. The job of the valve positioner is to provide compensatory force and to act as a counterbalance against any other variables which may impact valve stem position.

Magnetic sensors can be employed to determine the position of the valve stem. The magnetic sensor works by reading the position of a magnet attached to the stem of the valve. Other technologies can be employed, and all have differing ways of overcoming degrees of inaccuracy which may arise with wear, interference, and backlash. In addition to functioning as a positioner, control valve positioning devices can also function as volume boosters, meaning they can source and subsequently ventilate high air flow rates from sources other than their pneumatic input signal (setpoint). These devices can positively affect and correct positioning and velocity of the valve stem, resulting in faster performance than a valve actuator solely reliant on a transducer.

The inclusion of a positioner in a control valve assembly can provide extended performance and functionality that deliver predictable accurate valve and process operation. Share your valve automation requirements with a knowledgeable specialist and combine your process knowledge and experience with their product application expertise to develop an effective solution.

Friday, July 21, 2017

Pressure Motive Condensate Pumps



In a closed steam system, condensate must be returned to the feedwater side of the boiler. Moving this condensate effectively through the system is essential to maintaining design performance levels throughout the system. Condensate can be considered "spent steam", but still retains great value as preheated and treated feedwater for the boiler.

Three general methods are employed to transport condensate from where it is collected to where it is reused. If the facility layout permits, gravity can be the motive force to move the condensate back to the boiler. A second option is a mechanical pump, unsurprisingly called a condensate pump. The third common option is to employ system steam pressure to drive the condensate through the return piping and back to the boiler.

The concept of gravity return for the condensate is easy to envision....liquid flows downhill. Mechanical pumps, as well, are a well understood means of moving liquids. When the condensate collector reaches a certain fill level, the pump is energized and the liquid is forced through the return piping.

Using pressure as the motive force for condensate return involves coordinated operation of inlet, outlet, and vent openings to the condensate collection vessel. A float inside the collection vessel and a connected mechanism provide control of the valves at the vessel openings. In the video, you can see how the valve operating sequence provides for periods of condensate collection, then condensate discharge.

Share all of your steam system challenges with application specialists, combining your own process and facilities knowledge and experience with their product application expertise to develop effective solutions.