Hot Tip #15 - Condensate Return Lines
All condensate lines should be pitched down 1/4" per 10 feet (5 mm/m) to allow for drainage of the condensate by gravity. The most efficient return systems are, by design, not completely full of liquid and are not vented to the atmosphere. They are referred to as dry-closed systems. They handle condensate at steam temperature (i.e. not sub-cooled). Condensate return lines are specified to carry a condensate load, in pounds of condensate per hour (kg/hr). In fact, some of the condensate flashes to steam in the relatively low-pressure return line. Because the volume of flash steam is so much greater than the volume of the condensate, the return lines actually carry about 96% to 99% flash steam by volume. Therefore, condensate return lines should be sized to maintain a reasonable velocity of flash steam (under 7,000 fpm/30 m/s) at an acceptable pressure drop for the specified condensate flow rate.
(from our friends at Armstrong Traps)
Hot Tip #14 - Pipe Sizing Factors
When determining pipe size for steam systems, the following factors should be considered.
Initial steam pressure: the output pressure at the boiler or the main for branch piping.
Allowable pressure drop: the total pressure drop allowed from the source to the end of the line. This includes all drops from line loss, elbows, valves, etc. Pressure drops are usually due to friction between the steam and piping. Pressure drops are usually measured in psi/100 ft. Pressure drops for the total system should generally be less than 20% of the boiler operating pressure.
Flow rate: the amount of steam that must be supplied to the heat exchangers connected to the steam lines. Flow rate is measured in lbs/hr.
Steam velocity: the speed of the steam flowing through the lines, in feet per minute. Erosion and system noise increase with velocity. In general, steam velocities in process steam systems should be maintained between 6,000 and 12,000 fpm with a maximum of 15,000 fpm.
Future expansion: lines should be sized with the foreseeable future in mind. When in doubt, remember oversized lines usually present fewer problems than undersized lines
Remember: When steam lines are too large, purchase, installation, and fitting costs increase substantially over the more appropriate smaller lines. Additionally, because their surface is greater, these larger lines waste more heat through radiation
(From our friends at Armstrong Traps)
Hot Tip #13 - Steam Traps
“Drain each drip point with a separate trap.”
This rule for trapping should never be broken under any circumstances. Short-circuiting occurs when the condensate outlets from two heat exchange units are connected. Short-circuiting is likely whenever the drip points of two heat exchangers are drained with one trap, even if the two units appear to be identical. Any differences in condensing rates will result in a variance in the steam pressure drops of the two units. The condensate from the unit with the lower pressure drop will prevent air and condensate coming from the other unit from reaching the trap. The difference in condensing rates can seem insignificant, but it is not insignificant and must be taken seriously. This means that every iron chest should have a separate trap. If it is a split chest design ironer then each half will have a separate trap.
I was troubleshooting an ironer problem over the phone several years ago where a GM was insistent that one of his ironers was not large enough to dry his goods. Maintenance assured me that the trapping system was working fine. Not able to solve his problem over the phone, I jumped on a plane to find an eight-roll Hypro iron with a single trap for all rolls!
Hot Tip #12 - Mud Legs
Dirt pockets, (mud legs) provide a low-flow area where dirt and scale can settle out of the steam and condensate stream. Dirt pockets must be cleaned out periodically and, therefore, should be part of a regularly scheduled maintenance program.
Some traps are more susceptible to dirt than others. Strainers should be installed before any trap that may experience problems. Some traps are available with strainers that are built in. If you use a strainer, (highly recommended) it must be blown down periodically. As with the cleaning of dirt pockets, this process should also be a part of a regularly scheduled maintenance program. For ease of blow down, a globe or ball valve can be connected to the blow-down port of the strainer.
Hot Tip #11 - Steam Trap Installation
Unions provide a simple means for removing traps from a system for repair or replacement. If one union is used, locate it downstream from the trap. A trap can be removed between the union and the next connection point upstream (shutoff valve, strainer, or drip leg). If two unions are used, place them either at right angles or parallel. Avoid placing two unions in-line in either horizontal or vertical piping. Two unions in line make it difficult to separate the trap from the rest of the system if the lines are well anchored
If your facility has a number of traps that are identical in size and type, such as with ironers, a great deal of downtime can be avoided by standardizing connections. Use the same length inlet and outlet nipples on all traps and supply them with the same fittings, including unions. Keep a standby trap with identical fittings as a spare. Whenever a trap tests poorly, the unions can be loosened, the standby trap substituted, and the original taken in for repair.
A by-pass valve that is inadvertently left open defeats the function of the steam trap. If continuous service is necessary, place a standby trap in parallel with the primary trap.
Hot Tip #10 - Steam Trap Repair
Every year, hundreds of millions of dollars worth of steam is wasted in the U.S. Much of this loss is at the expense of companies that have made a huge investment in energy management - only to fail to establish a program to maintain steam trap efficiency.
For $40.00, (less than the cost of one steam trap) a video from Armstrong Corporation is available to teach you how to “correctly” repair steam traps. This video is a great investment. I highly recommend it!
"Guidelines for Steam Trap Repair"
It offers an outline for the establishment of a plan for identifying faulty traps and returning them to effective operation. The first part of the tape provides guidelines to follow in the inspection and repair of any trap.
Hot Tip #9 - Latent heat of evaporation
One pound of water at 32 degrees F. plus 180 BTU’s = One pound of water at 212 degrees F. One pound of water at 212 degrees F. plus 971 BTU’s = One pound of steam at 212 degrees F. and at 0 PSIG. One pound of steam at 212 degrees F. and at 0 PSIG plus 46 BTUs = One pound of steam at 366 degrees F. and at 150 PSIG.
To one pound of water at 32 degrees, we have added a total of 1197 BTU’s to produce one pound of steam at 366 degrees F. and at 150 PSIG.
Out of the total 1197 BTU’s added, 971 BTU’s were required to change its state from liquid to vapor (81.1%). This is one of the reasons that steam is such a great conveyor of energy; but only if you convert the steam back into a liquid (condensate) in a useful process.
When you see steam exiting your washers this is not a useful process. You have not captured the 971 BTU’s (latent heat of evaporation) and you are wasting more than 81.1% of this available energy. “Steaming up” in a washer needs to be avoided as much as corporate taxes, swine flu, and traffic cameras! If you must steam up, reduce the steam rate of flow. The best way to do this is with a steam pressure-reducing valve.
Be aware that steam exiting your washers is a hazardous substance. Boiler treatment chemicals, which are present in this steam, are the most hazardous chemicals within most laundries. Some are class 4 carcinogens.
Hot Tip #8 - The Triboelectric Effect
Are you having ironing problems due to the triboelectric effect, also known as triboelectric charging?
This is a type of contact electrification in which certain materials become electrically charged after they come into contact with another different material and are then separated, such as through rubbing. The polarity and strength of the charges produced differ according to the materials, surface roughness, temperature, strain, and other properties. Thus, it is not very predictable, and only broad generalizations can be made. This property, first recorded by Thales of Miletus, suggested the word “electricity”, from the Greek word for amber, ēlektron. Other examples of materials that can acquire a significant charge when rubbed together include blended textiles when rubbed with other blended textiles.
As the Relative Humidity (HR) goes down, or your goods become too dry, this Triboelectric charging will increase. Static bar(s) installed on the ironer or the use of certain fabric softeners are the most common solutions. The most successful solution is to prevent your goods from becoming too dry before they enter the ironer. The wetter the goods entering the ironer the less TRIBOELECTRIC EFFECT you will encounter.
Hot Tip #7 - Thermo Oil
My question is would switching to all ironers on thermal oil be more efficient than steam?
What are the pros and cons of Oil Vs Steam?
Oil Pros:
- Oil can be heated to higher temperatures. (>400 F), steam at 150 PSIG = 366 F.
- Oil will be at a lower pressure, Typically 30 to 40 PSIG not 100 PSIG or greater as with steam.
- Fewer steam traps are required. (None on oil systems)
- Less make-up water, boiler water treatment, boiler chemicals, boiler blow-down.
- Lower TDS (total dissolved solids) in discharged sewer water.
- Little if any internal pipe corrosion
- No catastrophic expansion of oil during containment vessel rupture. (Steam expands to 1500 times boiler water volume)
Cons:
- Addition capital investment. (Oil system & steam system)
- Electrical cost increases. (Oil must be pumped; oil pumps are larger than boiler feed water pumps)
- Additional maintenance. (Oil heater & pumping system)
- Additional building space is required to house the oil system
- Heated oil can burn (be destroyed) during an electrical outage if not circulated. (standby, non-electrical pump required)
- Oil has a limited life expectancy and is considered hazardous waste when disposed of in most states.
- Oil can catch on fire.
- Oil is considered less safe. A small pinhole leak can send hot oil 40 to 60 feet. (Steam only a few feet)
- Oil “spills” are much harder to clean up. (Oil spills may require HAZMAT involvement.)
- Additional air emission permits are required.
- Higher temperature equals greater thermo losses in the delivery system & in the oil heater exhaust gases. Some of these additional losses are heating up your already too hot laundry.
Hot Tip #6 - Iron Removal
Do you have a problem with iron in your water softeners?
Here is a simple three-step solution:
- Dissolve two pounds of salt and four pounds of Ferosol 1-300 in three gallons of water for each cubic foot of resin in the softener.
- Pump solution into Brine well just before regeneration.
- After regeneration with this solution, regenerate the unit a second time under normal regeneration parameters and return to service.
Ferosol 1-300 is a Bond Chemical product.
Your chemical supplier may have a substitute for Ferosol 1-300