Understanding & Solving Heat Transfer Equipment Stall

Heat transfer loop

Stall can most easily be defined as a condition in which heat transfer equipment is unable to drain condensate and becomes flooded due to insufficient system pressure.

Stall occurs primarily in heat transfer equipment where the steam pressure is modulated to obtain a desired output (i.e. product temperature). The pressure range of any such equipment ( coils, shell & tube, etc....) can be segmented into two (2) distinct operational modes, Operating and Stall.

Operating: In the upper section of the pressure range the operating pressure (OP) of the equipment is greater than the back pressure (BP) present at the discharge of the steam trap. Therefore a positive pressure differential across the trap exists allowing for condensate to flow from the equipment to the condensate return line.

Stall: In the lower section of the pressure range the operating pressure (OP) of the equipment is less than or equal to the back pressure (BP) present at the discharge of the steam trap. Therefore a negative or no pressure differential exists, this does not allow condensate to be discharged to the return line and the condensate begins to collect and flood the equipment.

You can read the entire Armstrong technical paper below.

Visit this link to download your own copy of Armstrong Fluid Handling: Understanding and Solving Equipment Stall.

Understanding & Solving Heat Transfer Equipment Stall from Mead O'Brien, Inc.

Traps for Sour Gas Service

Armstrong Series 300

What is “sour gas”? 

In the oil and gas industry, “sour gas” refers to natural gas that is contaminated with hydrogen sulfide (H2S or “sulfide”). “Sour crude,” similarly, is crude oil that contains hydrogen sulfide. These are naturally occurring conditions, but definitely not desirable. Aside from the environmental pollution problems with “high-sulfur” fuels, there are some serious corrosion problems that can affect many materials. Liquid drainers (drain traps) and strainers are the most common Armstrong products ordered for sour gas service. A few other products are sometimes specified, notably inverted bucket air traps. An inquiry may be accompanied by an extensive specification of H2S concentrations; there may be a line indicating “Sour Gas Service;” or may only be the note “NACE.” This is a reference to Standard MR0175-93 published by the National Association of Corrosion Engineers (NACE).

What is the problem? 

H2S under pressure permeates into the crystalline structure of the metal and strains the structure of the crystal. This reduces its ability to deform in a ductile manner. The net effect is to make the material brittle. In the presence of external stresses due to applied pressure or loads, or internal stresses due to cold working or welding, parts may fail by cracking without any warning. This process is called Sulfide Stress Cracking (SSC). SSC is affected by many parameters, including: · Composition, strength, heat treatment, and microstructure of the material; · Hydrogen ion concentration (pH) of the environment; · Hydrogen sulfide concentration and total pressure; · Total tensile stress; · Time and temperature. Choice of products and their limitations. Inverted bucket traps (primarily for air trap service) should be selected from the Series 300 traps. The bucket and mechanism (except valve and seat) will be annealed to eliminate the locked-in stresses from the stamping operations. The valve and seat will be made from Type 316 stainless, without additional heat treatment. Cast iron bucket weights are permitted, since they are not stressed in tension. Special bolting is required only if the sour environment is also outside the trap.

Download the Sour Gas Trap Selection Guide Here

Wireless Monitoring Technology Keeps Watchful Eye on Steam Trap Operation

Model ST5700

The Armstrong Intelligent Monitoring Model ST5700 is a wireless monitoring technology that efficiently monitors and evaluates steam trap operation. It identifies the conditions of a steam trap to determine significant problems that could put your operation at risk and can accurately detect potential issues such as plugged and blow thru steam traps. 

The AIM®ST5700 helps identify the root cause while you minimize production losses and reduce energy consumption. Using non-intrusive technology combined with WirelessHART, the AIM®ST5700 is the ideal solution for any temporary or permanent 24/7 steam trap monitoring.

For more on its operation and use, please read the document below.

Wireless Steam Trap Monitor: Theory of Operation from Mead O'Brien, Inc.

For more information, contact:
Mead O'Brien
www.meadobrien.com
(800) 892-2769

A Better Alternative to Magmeter for Unpolished Condensate Flow Measurement

Veris Accelabar 

A large University was using magnetic flowmeters (Magmeters) to measure the flow of boiler feed water downstream of a condensate polisher. There were occasional system upsets that required the condensate polisher to be bypassed. When this happened, large amounts of debris would be released downstream and pass directly through the Magmeter, causing a build-up of foreign material on the internal sensing surfaces.

A magnetic flowmeter uses an electric current applied to a coil which produces a magnetic field. When conductive liquid flows through the magnetic field, a small voltage, proportional to the liquid velocity, is induced. As long as the interior surfaces of the Magmeter are clean and unobstructed, the meter accurately measures flow. If they get dirty or coated, all bets are off.

It was in the above mentioned upset situations where the University maintenance people were having problems. When upsets occurred, and the condensate polisher had to be by-passed, it meant the Magmeter would also have to be serviced because accuracy could no longer be guaranteed. Servicing the Magmeter was slow and costly. It meant shutting down the line, draining the pipe, removing the flowmeter, cleaning, and then putting it all back together.

Armstrong International’s Veris Group was called in for a consult. After review,  the Veris Group recommended installing an Accelabar® flow meter to offer an alternative solution that could provide reliable flow measurement regardless of an upset condition like unpolished condensate. The Accelabar provided a flow range of 22.5:1 turndown in flow, in a limited straight run scenario. In the past, two transmitters were required to provide the best accuracy across the entire range of the Accelabar. Veris was able to use the Foxboro IDP 10S with its FoxCal™ technology in order to have a combined percent of rate accuracy solution.

The new transmitter installation has 11 separate calibrations loaded into the device. As the differential pressure from the primary element is measured, the transmitter chooses the correct calibration curve. Veris’ solution delivered performance that was previously unattainable with a single differential pressure transmitter.

The Accelabar and Foxboro combined to be best solution, and the Accelabar flow meter is now the University's standard for the boiler feed water measurements.

For more information, contact:

Mead O'Brien, Inc.
10800 Midwest Industrial Blvd
St Louis,  MO 63132
314-423-5161
314-423-5707
www.meadobrien.com

Part 3: What Steam Is, How Steam is Used, and the Properties of Steam

Mead O'Brien Steam Experts

Steam is the gaseous phase (state) of water and has many domestic, commercial, and industrial uses. There are two categories of steam - wet steam and dry steam. In dry steam, all the water molecules stay in the gaseous state. In wet steam, some of the water molecules have released their energy (latent heat) and begin condensing into water droplets.

Steam, usually created by a boiler burning coal or other fuels, became the primary source of energy for mechanical movement during the industrial revolution, ultimately being replaced by fossil fuels and electricity.

Steam has many commercial and industrial uses. In agricultural, steam is used to remediate and sterilize soil. In power generation, approximately 90% of our electricity is created using steam as the working fluid to spin turbines. Autoclaves use steam for sterilization in microbiology labs, research, and healthcare facilities. Many commercial and industrial pieces of equipment are cleaned with steam. Finally, commercial complexes, campuses and military buildings use steam for heat and humidification.

The following video, the FINAL part of a three part series titled “What Steam Is, How Steam is Used, and the Properties of Steam” provides the viewer with an exceptional basis to build from. Special thanks to Armstrong International who created the original work.

For more information on any industrial or commercial steam application, contact:

Mead O'Brien, Inc.

www.meadobrien.com

(800) 892-2769

Part 2: What Steam Is, How Steam is Used, and the Properties of Steam

Steam is the gaseous phase (state) of water and has many domestic, commercial, and industrial uses. There are two categories of steam - wet steam and dry steam. In dry steam, all the water molecules stay in the gaseous state. In wet steam, some of the water molecules have released their energy (latent heat) and begin condensing into water droplets.

Steam, usually created by a boiler burning coal or other fuels, became the primary source of energy for mechanical movement during the industrial revolution, ultimately being replaced by fossil fuels and electricity.

Steam has many commercial and industrial uses. In agricultural, steam is used to remediate and sterilize soil. In power generation, approximately 90% of our electricity is created using steam as the working fluid to spin turbines. Autoclaves use steam for sterilization in microbiology labs, research, and healthcare facilities. Many commercial and industrial pieces of equipment are cleaned with steam. Finally, commercial complexes, campuses and military buildings use steam for heat and humidification.

The following video, the second part of a three part series titled “What Steam Is, How Steam is Used, and the Properties of Steam” provides the viewer with an exceptional basis to build from. Special thanks to Armstrong International who created the original work.

For more information on any industrial or commercial steam application, contact:

Mead O'Brien, Inc.

www.meadobrien.com

(800) 892-2769

Part 1: What Steam Is, How Steam is Used, and the Properties of Steam

Steam is the gaseous phase (state) of water and has many domestic, commercial, and industrial uses. There are two categories of steam - wet steam and dry steam. In dry steam, all the water molecules stay in the gaseous state. In wet steam, some of the water molecules have released their energy (latent heat) and begin condensing into water droplets.

Steam, usually created by a boiler burning coal or other fuels, became the primary source of energy for mechanical movement during the industrial revolution, ultimately being replaced by fossil fuels and electricity.

Steam has many commercial and industrial uses. In agricultural, steam is used to remediate and sterilize soil. In power generation, approximately 90% of our electricity is created using steam as the working fluid to spin turbines. Autoclaves use steam for sterilization in microbiology labs, research, and healthcare facilities. Many commercial and industrial pieces of equipment are cleaned with steam. Finally, commercial complexes, campuses and military buildings use steam for heat and humidification.

The following video, the first part of a three part series titled “What Steam Is, How Steam is Used, and the Properties of Steam” provides the viewer with an exceptional basis to build from. Special thanks to Armstrong International who created the original work.

For more information on any industrial or commercial steam application, contact:

Mead O'Brien, Inc.
www.meadobrien.com
(800) 892-2769

Mead O'Brien: Steam and Hot Water System Experts

Let Mead O’Brien help you create a sustainable Steam Trap Management Process!

• Trained Survey Technicians 
• Traps located and identified, tagged with SS tag #, and data logged with up to 27 fields of useful data per trap 
• Executive summary, Failed trap report with steam & dollar losses, detailed Log sheets, and Recommendations are all provided in a professional report. 
• Monitoring options presented for critical service applications 
• Steam flow measurement design 
• Heat recovery potential 
• Training options in a live steam lab 

Realize the Savings Now!

• Reduce steam & condensate losses 
• Reduce loss of boiler chemicals 
• Improve heat transfer performance 
• Prevent coil and heat exchanger damage 
• Minimize water hammer hazards 

Mead O’Brien and Armstrong, more than 85 years of Steam & Hot Water System Optimization

• Steam Distribution
• Process Heat Transfer and Control
• Condensate Return
• Heat Recovery Opportunities
• Process, Ambient & Combustion Air
• Steam Trap Surveys & Database Creation 
• Humidification Assessment
• Application issues
• - Coil Freezing Issues
• - Poor Heat Transfer & Steam Control - Water Hammer Issues
• - High Backpressure
• Steam & Condensate Measurements, Control & Monitoring

Learning Systems:

• Armstrong University
• Over 125 web-based courses 
• Mead O’Brien Live Steam Lab
• Content Tailored for Plant Need

Steam Trap Testing Guide for Energy Conservation

Annual steam trap testing schedule

Below is a steam trap testing guide (courtesy of Armstrong International) to maximize efficiency and conserve energy. This guide discusses:

• Steam Trap Testing Procedure 
• Tips On Listening 
• Inverted Bucket 
• Float & Thermostatic Trap 
• Disc Trap 
• Thermostatic Trap 
• Sub-Cooling Trap 
• Traps on Superheated Steam

CAUTION: Valves in steam lines should be opened or closed by authorized personnel only, following the correct procedure for specific system conditions. Always isolate steam trap from pressurized supply and return lines before opening for inspection or repair. Isolate strainer from pressurized system before opening to clean. Failure to follow correct procedures can result in system damage and possible bodily injury.

Steam Trap Testing Guide for Energy Conservation from Mead O'Brien, Inc.

Steam System Condensate - Save Big by Managing its Proper Return

Recover/return steam condensate

An often overlooked place to find savings in the operation of a manufacturing plant is the steam condensate return system. Returning condensate to the boiler feedwater system saves energy by returning pre-heated water, thus requiring less energy to maintain the feed water temperature. Furthermore, condensate is pre-treated, eliminating the need for additional expensive treatment.

Steam use in modern plants is everywhere. The condensate derived from its use is an asset that needs to be recycled. Older steam systems may have poor condensate return piping, or none at all. For these situations, creating or extending return lines should be considered. Steam traps in older systems are also suspect. Older traps are not as efficient or reliable as newer designs.

According to Armstrong International’s Senior Utility Systems Engineer Novena Iordanova, steam traps are very important in the condensate return/feedwater cycle. She believes the first purpose of a steam system is to deliver steam to a users defined area of need, and second, to return the resulting condensate back to the boiler. Unfortunately, in many cases the second goal is overlooked.

In older plants, a complete steam system evaluation, and many times an overhaul, is required. Professionals should be called in as plant maintenance staff typically doesn’t have the expertise required. The reasons for steam system degradation are common in the life cycle of plant operation. Over time, plant upgrades, new lines, expansion, and new equipment can have a significant detrimental effect on condensate return systems. The focus usually goes to the main headers and distribution, but condensate return doesn’t receive the same attention. The result can be a steam system that is no longer efficient - meaning high back pressures, water hammer, broken or freezing pipes, and leaks. At that point, the plant needs professional help for a complete system review.

Steam trap
(courtesy of Armstrong)

The most important player in condensate recovery is the steam trap. Steam traps play the critical role of separating steam and condensate at the moment its formed. Traps discharge the condensate downstream to the boiler for reuse. Proper sizing, installation, and maintenance from the start will save huge amounts of money in terms of energy savings and maintenance time.

Frequent and regular inspections of steam traps are essential, but in reality they are many times postponed or rescheduled. Steam trap inspection is tough work. Traps are usually located in hard to see, hot, and tight areas. Over time, the difficulty (combined with the perceived low priority) degenerates to spotty inspection routines, higher trap fail rates and higher steam costs.

The good news is that steam trap monitoring systems now exist that can monitor the performance of steam traps and alert maintenance when things start to deteriorate. Steam trap monitoring systems report conditions that point to filature, and also alarm when things break down. Accordingly, maintenance is in a position to take preventive action, or make swift repairs. Any plant with a considerable number of stream traps should strongly consider deploying a steam trap monitoring system.

Steam trap monitoring systems monitor the thermal and acoustic characteristic of the trap and report any significant changes. Today many monitoring systems are wireless, and many operate on common plant communication systems such as WirelessHART, a communication protocol gaining worldwide acceptance.

Its important to mention here though, the on the most common mistake plant personnel make when it comes to their system is also one of  the most obvious - insulation. The use of high quality, well maintained insulation, installed to allow access to steam components is critical. The energy savings alone from well insulated pipes and traps is argument enough for making the initial time and dollar investment for proper insulating.

If you’re a plant manager and are looking for significant measurable and meaningful ways to lower energy costs, you must consider a well planned and well executed steam trap management program.