How Efficient Is Your
Steam Distribution System?

Frederic A. Hooper, Jr. and Ronald D. Gillette

There's an old management saying, "If you don't measure it, you don't get it." Nobody measures their steam distribution system efficiency because there is no generally accepted method. So your system's efficiency is probably low -- not the 70-90% of the boiler, but instead the 30-60% of a neglected system. This paper proposes a method of measuring it.

 

Steam Distribution System Efficiency Percentage

The purpose of a steam distribution system is to deliver energy from the boiler to where it is needed. A perfect steam distribution system would deliver it without any delivery losses. This would require perfect piping insulation, perfect steam traps and perfect condensate recovery systems, with no maintenance needed.

Real steam distribution systems are built of components that decay, and are maintained by human beings. Real systems have losses from less-than-perfect insulation, leaking steam traps, flash steam and dumped condensate. Maintenance is expensive and may be delayed by lack of funds or personnel. The delivery loss of a real steam distribution system is much higher than the zero delivery loss of a perfect system.

Having described an "ideal" and an "actual" value, we could find the system efficiency by dividing the energy needed by the energy supplied. Notice this is "ideal divided by actual", the reverse of most percentage calculations. This reversal is necessary because we are measuring what we provide, not what we get.

We also have difficulty finding the "ideal" value because its calculation is complex. A computer model of the steam distribution system will make it possible to calculate system efficiency from the easier-to-obtain numbers in the model. This computer model will need to calculate some values so they can be compared with actual values for calibration. It should also use currency, as this is the only common basis for comparison across a complex system.

 

Modeling The Steam Distribution System

Condensate flowing through steam traps represents the energy leaving the distribution system. The model can calculate the amount of energy that is leaving by combining the condensate flow and steam pressure at the traps. Classifying the steam traps into "working" and "drip" traps separates those using energy from those transporting energy.

Energy needed: Condensate from the working traps represents the energy the steam system was built to provide. Estimating their condensate flow is the first step towards building the necessary model. By combining the condensate flow and steam pressure at the working traps, the model can calculate the energy provided by a perfect system.

Energy transport: Drip trapsā condensate flow results from less-than-perfect piping insulation. Combining the condensate flow and steam pressure at the traps in the same manner as above provides the energy transportation cost of the system. The model can also calculate the energy loss from less-than-perfect piping insulation. This second measure of energy loss provides calibration of this portion of the model.

Lost condensate: When condensate is lost from the system it must be replaced. If it were not lost, it would be returned to the boiler still heated. If it is lost, its components ÷ water, heat and chemicals ÷ must all be replaced.

Flash steam: Steam is lost from the distribution system through flash steam and leaking steam traps. Flash steam occurs when the condensate from a steam trap is above the boiling point. Without a flash recovery system in place, the flash steam will be lost.

Steam traps: Leaking steam traps are a major source of energy and condensate losses in most distribution systems. As these losses are hidden, many companies don't maintain their steam traps. Those that attempt to maintain them typically do so with annual test-and-replace, so the average leaking trap has been leaking for six months before it is found. More sophisticated maintenance methods are rarely employed at present. The model should include various steam trap maintenance methods with their labor and parts costs as well as lost steam.

Condensate recovery system: Steam from leaking traps quickly overwhelms any flash recovery systems and leaves the distribution system. However, it does not do so constantly. Non-condensable gases are mixed with the steam through vents and become mixed with the condensing condensate. If the condensate is later heated to boiling by leaking traps, the gases are released and cause the condensate piping to deteriorate much more rapidly than it should. Also, if live steam reaches condensate pumps they need more frequent and extensive maintenance.

 

A Steam System Modeling Program: Steam$$

Steam$$ is a program that models a steam distribution system, calculates a value for system efficiency and allows calibrating the model. Using limited information, Steam$$ calculates the steam distribution system's actual cost from the losses discussed above. It also calculates the system's ideal cost, divides the two numbers, and gives the percent result. This accurately represents the steam distribution system. In addition to efficiency measures, it provides figures for calculating the benefit (and some costs) of improvements to the steam system. Note: The Steam$$ program referred to above is available from author Fred Hooper at no cost.

 

Conclusion

The calculation of steam distribution system efficiency is more complex than calculating boiler efficiency but is straightforward with a computer model. An additional benefit of this calculation is that it helps evaluate possible system improvements. Finally, comparing steam distribution system efficiency across companies and industries can provide an important competitive benchmark.

Fred Hooper
Steam Conservation Systems
12 Laurel Lane
East Greenwich, RI 02818
(401) 886-4164

 


(from the installer program documentation)

 

Installing Steam$$ and the Trapo Demo

Run the INSTALL.EXE program on the disk. It allows you to install either or both programs and suggests placing all files in a STEAM$$ directory on the C: drive. However, you can place and name the directory whatever you wish.

Running the programs:

DOS: The installation program places batch files in the C: directory. Type either of the program names (STEAM$$ & TRAPDEMO) at the C:> prompt.

Windows 3.x and Windows for Workgroups 3.x: Open the group where you want to place the program icons. You will have to go through the following steps for each program. Choose File, New, select "Program Item", and push [OK]. Enter the program name in the description field (e.g. Steam$$). Enter the location and the ".PIF" file name (e.g. "C:\STEAM$$\STEAM$$.PIF" or "C:\STEAM$$\TRAPDEMO.PIF").

Push the [Change Icon] button and then the [OK] button when prompted. Enter the ".ICO" file in the "File Name"" field (e.g. "C:\STEAM$$\STEAM$$.ICO" or C:\STEAM$$\TRAPDEMO.ICO"). Push the [OK] button in the "Program Item Properties" dialog box and the program item will be set up. You can then start the program by double-clicking on the icon.

Windows 95: Use "My computer" to open the programs' folder. Locate the two icons (arrows on each of them), "right click" on them, choose Copy, place mouse on desktop, "right click" and choose Paste Shortcut. You may have to "right click" the icons to change properties to match the folder name if you didn't name the directory STEAM$$.

 


About Fred Hooper: I am an ex-academic (finance, of all things) who wrote a simple program to help a friend manage 4500 steam traps. It has grown into a full-blown maintenance management system for steam traps, named Trapo. By following the principles of predictive maintenance, using some proprietary optimizations and automating repetitive tasks (like ordering replacement parts and preparing work orders), it eliminates most trap testing and greatly reduces maintenance costs, hassles and leaked steam. A demo version is available from the author.
(from the program documentation)

 

About Steam$$ and the Trapo Demo

Steam$$ Version 2.21

Steam$$ introduces you to Steam Conservation Systems' state-of-the-art approach to steam system management.

Installing Steam$$

Run the INSTALL.EXE program on the disk. It will suggest placing all files in a STEAM$$ directory on the C: drive. However, you can place and name the directory whatever you wish.

What is Steam$$?

Steam$$ is an modeling (simulation) program designed to help you analyze your current steam distribution system costs and how they can be reduced.

Running Steam$$:

DOS: The INSTALL program places a batch file in your C: directory. Type the program names (STEAM$$) at the C:> prompt.

Windows 3.x and Windows for Workgroups 3.x: Open the group where you want to place the program icon. You will have to go through the following steps: Choose File, New, select "Program Item", and push [OK]. In the description field enter the program name. In the command line field enter the location and the ".PIF" file name (e.g. "C:\STEAM$$\STEAM$$.PIF"). Push the [Change Icon] button and then the [OK] button when prompted. Enter the ".ICO" file in the "File Name" field (e.g. "C:\STEAM$$\STEAM$$.ICO"). Push the [OK] button in the "Program Item Properties" dialog box and the program item will be set up. You can then start the program by double-clicking on the icon.

Windows 95: Use "My computer" to open the folder where you installed the programs. Locate the icon (an arrow on it), click on it and drag it to the desktop.

You may have to "right click" the icon to change properties to match the correct folder descriptions if you changed this. You may also have to press the "Change Icon" button and "browse" in the directory for the proper icon.

Starting to use Steam$$

At the bottom of the screen is a list of the function keys [F?] and what they do. Most of them move you to another section of the program, returning to the same field you were on before (if you were there before). Additionally, pressing the backslash key [/] brings you to a short menu allowing you to save your work and exit.

Use of [F1] Help

Help is context-sensitive. That is, the help screen that appears when you press [F1] depends on where you are in Steam$$. From that screen you can reach other help screens by highlighting one of the red lines and pressing [Enter].

A good way to get acquainted with Steam$$ and the thinking behind it is to wander around the program pressing [F1] on screens and information that catches your attention. Below is a brief discussion of the four major parts of Steam$$ and how you might use them.

Annual Totals

This section shows the annual costs of your facility and its losses. It also helps you fine-tune your estimates so the overall quantities calculated by Steam$$ can be compared to figures from your facility. The %use, condensate loads, and piping are the inputs that should be calibrated. Many facilities have drastically oversized their traps to make sure that condensate is removed from the pipes.

Steam Traps

Ass'n - This part of Steam$$ has places for you to enter general information about your steam system and traps. The input fields have descriptions and help through the [F1] key. Use the [PgUp] and [PgDn] keys to explore this section.

Result - This part of Steam$$ shows the results of Steam$$'s analyses. The fields have descriptions and help through the [F1] key. Use the [PgUp] and [PgDn] keys to explore this section.

Det - This holds detailed information about your steam traps.

Orifice - This section calculates the annual leakage costs of (up to) ten orifice traps. Their steam losses are included in annual totals.

Piping System

This section allows you to enter information on your piping system. You should enter the length, diameter, insulation efficiency, and number of fittings in each piping run (and whether they are insulated). The energy losses in this section are included in annual totals.

The Results of Your Analysis

After you have entered your trap information and set the overall assumptions at values that seem correct you can interpret the results. However, before this you should try varying the assumptions a bit to find out how much the results change. The most detailed results are available for steam traps. We will discuss that section first.

Steam Trap Results

Most people find that there is a 20% reduction in annual trap costs from using optimum test intervals. However, this is generally overshadowed by the 30-50% reduction from Adj Periodic Replacement and a 40-80% reduction from predictive maintenance. The amount of savings you find depends on how many of your traps can be represented by test samples and what kinds of traps you have.

Moving to predictive maintenance requires that you know the installation date and your traps' C-100 trap lives (for Constant-100% use, the life if the trap were used all day every day). Few firms have installation dates for all their traps. If you have them you can obtain the benefits of predictive maintenance more quickly with less investment. Otherwise you should begin to replace many of your traps without testing them further. Use the ROI results for each trap type to guide your trap replacements. However, if many traps are leaking, replacing only part of them will simply cause the other leaking traps to leak more. You do not get the full savings potential of this approach until most of the leaking traps have been replaced.

Piping System Results

The piping system results give you a good idea of how much your system departs from what it should be. To explore this further, Steam$$'s help recommends programs that treat this material in more detail. Look under "About Steam$$" and then look at "What Steam$$ is Not."

 

The Trapo Demo Version 3.20

The Trapo Demo introduce you to Steam Conservation Systems' state-of-the-art approach to steam trap management.

Installing The Trapo Demo

Run the INSTALL.EXE program on the disk. It will suggest placing all files in a TRAPDEMO directory on the C: drive. However, you can place and name the directory whatever you wish.

What is The Trapo Demo? Trapo is the steam trap maintenance management program that makes it possible to obtain the low steam trap costs predicted by the Steam$$ program.

The Trapo Demo has many of the screens of Trapo, including most of the Help Screens. Additionally, it can use the same commands as Trapo so that you learn to use Trapo by using it.

Running The Trapo Demo:

DOS: The INSTALL program places a batch file for The Trapo Demo on your C: directory. Type the program name (TRAPDEMO) at the C:> prompt.

Windows 3.x and Windows for Workgroups 3.x: Open the group where you want to place the program icon. You will have to go through the following steps:

Choose File, New, select "Program Item", and push [OK]. In the description field enter the program name. In the command line field enter the location and the ".PIF" file name (e.g. "C:\STEAM$$\TRAPDEMO.PIF").

Push the [Change Icon] button and then the [OK] button when prompted. Enter the ".ICO" file in the "File Name" field (e.g. "C:\STEAM$$\TRAPDEMO.ICO"). Push the [OK] button in the "Program Item Properties" dialog box and the program item will be set up.

You can then start the program by double-clicking on the icon.

Windows 95: Use "My computer" to open the folder where you installed the program. Locate the icon (an arrow on it), click on it and drag it to the desktop.

You may have to "right click" the items to change properties to match the correct folder descriptions if you changed this. You may also have to press the "Change Icon" button and "browse" in the directory for the proper icon.

Starting to use The Trapo Demo

Try the commands and look at the help files. Most screens have either a help file or an on-screen explanation. Think how you would use Trapo to order trap replacements and/or to input information on your traps. Look at the Test Sample and Automatic Replacement sections to think about how you would organize its use for your facility. The results of a Steam$$ analysis will provide the initial inputs for Automatic Replacement.

Please contact us with any questions, comments or suggestions.

Steam Conservation Systems
12 Laurel Lane
East Greenwich, RI 02818
Phone: (401) 886-4164
FAX: (401) 885-1427
Internet: fahooper@trapo.com
CompuServe: 102036,2563


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