McKenzie’s Boiler Blog

The bottled water industry today is very lucrative business. In 2001 a bottled water industry revenues grew by over 13% in the U.S. alone.  Why do we put so much effort into going out to buy bottled water?  Most would say that bottled water is healthier for you.  The many filtering processes of bottled water remove harmful chemicals that can lead to bad tasting water. 

What about your boiler? The same harsh chemicals that you do not want to ingest get carelessly forced into your boiler which, in turn, can cause many mechanical problems.  The common water supplied in most areas can corrode metal, choke off fluid passages, and cause pressure vessels to over heat to the point of failure. Only one–sixteenth of an inch thick of scale deposited into the tubes of a firetube boiler can cause a 12.5% increase in fuel consumption.

This means to keep you boiler running at optimum performance you should implement a water treatment system.  Some of the basic pieces of equipment that you should look into are: 

• A Chemical Feed System
• A Water Softener System
• A Bottom and/or Surface Blow Down System
• A Deaerator or Boiler Feedwater System with Sparge tube
• A Condensate Return System

By implementing these systems you can keep your boiler running at its highest efficiency, reducing fuel costs.  So now you have more money for bottled water.

As the price of oil continues to rise the search for an alternate fuel is stronger than ever.  As a manufacturing facility, you understand that the cost of fuel drives up the cost of everything.  From the cost of production, to the cost of shipping the high oil prices affect all business matters.

Compressed natural gas (CNG) is a very safe and environmentally friendly fuel.  Natural Gas Buses emit 50% less nitrogen oxides (NOx), 90% less sulphur oxides (SOx), and 97% less small particulates than conventional diesel buses. Now turn the bus into 4 or 5 forklifts and the indoor air quality of your warehouse just got a whole lot better.

 The use of compressed natural gas (CNG) has helped major companies save money on the prices of fuel.  Coca-cola Enterprises, Walt Disney World, along with a number of military bases have put in CNG stations to refuel numerous vehicles. Giving them an edge on the competition.

The safety and availability of natural gas is shown everywhere.  From cooking dinner to heating your home natural gas is all around us.  More than 90% of our natural gas is produced in North America, reliving us of our dependency on foreign oil.  CNG is a lot safer than conventional gasoline not only in the way it is stored but also in its ignition.  If CNG is concentrated in air below about 5 percent and above about 15 percent, natural gas will not burn. The high ignition temperature and limited flammability range also make accidental ignition or combustion of natural gas unlikely. 

Converting a fleet of forklifts or busses to CNG is easier than one might think.  There are CNG conversion kits available to help any company convert to CNG completely or partially. For a complete list of vehicles available for CNG conversion kits and more information on CNG visit CNG conversion kits.

For those of you with mechanical rooms that include engines, compressors or engine driven generators, the need for a constant, reliable method of feeding oil has always been a concern. When asked for the best method to accomplish this, we have always suggested using an oil level regulator along with a properly sized oil supply tank and stand.

An oil level regulator automatically maintains the required oil level in an engine and can be directly mounted on the engine with a simple mounting bracket. From a separate oil tank at or near the engine, the regulator delivers only that amount of oil that is required to maintain a constant level in the engine crankcase. Care must be taken to choose an oil level regulator that is insensitive to vibration.

When installed along with an oil tank supply and stand, many customer report substantial savings in oil consumption. This system also eliminates manually checking oil levels and frequent manual fillings.

Oil supply tanks and stands are available in 5, 10, 15, 30 and 55 gallon sizes. Definitely a system worth considering!

Oil Supply Tanks
Oil Level Regulators

Burner turndown ratios have been promoted, with great success, over the years. The term turndown ratio may be defined as the ratio of maximum fuel input rate to minimum fuel input rate on a variable input burner. Typically these rates have been 5:1 with newer burner designs offering 10:1 turndown ratio or more.

Why would anybody want a high turndown burner can be answered in the advantages offered by closely controlling firing rates. These advantages include:

• Reducing stand-by losses
• Eliminating thermal cycling
• Minimizing wear and tear on the burner

When a boiler is in idle, that is to say not firing, air is drawn through the vessel as a result of the stack effect. This air robs precious heat from the system. During boiler start-up and shut down this stand-by loss is magnified as a result pre and post purge cycles.

Another advantage to higher turndown is the reducing thermal cycling. Boilers that are quickly heated up and cooled down are more susceptible to material failure due to the expansion and contraction associated with on again off again operation. This is especially rough on refractory and other brittle materials used in boiler construction. By gradually increasing or decreasing firing rates, these effects are greatly minimized.

It goes without saying that the wear and tear on burner linkages, motor starters, pilot gas valves and main gas valves are also minimized. But, perhaps the most important reason to consider a high turndown burner is the money you would save.

Another avenue to explore is upgrading your burner to linkageless controls. In many cases an upgrade such as this would improve turndown performance as well as low-fire combustion efficiency. 

We read a great article online that addresses this very subject in a clear concise manner. The Article, Upgrading Burner Controls, was published by Heating/Piping?Air Conditioning Engineering in the June 2007 issue. It was written by Bertram Leng, Director of the Combustion Controls Product Group, Group Region Americas for Siemens Building Technologies, Inc.

Mr. Leng makes a strong case for upgrading burners and burner controls to improve efficiencies. He points out that, with limited budgets, facilities managers can still improve boiler performance without buying new boilers. He sites a specific example in which a hospital was faced with the dilemma many of us face when trying to deal with older equipment.

It is a worthwhile article and we suggest you take a moment to read through it.
The article can be found at   http://www.hpac.com/GlobalSearch/Article/67895/

mckenziecorp.com

BOILER - LOW WATER

The effect of low water in a boiler could result in, at the least, a leakage and, at the worst, a catastrophic explosion, depending on the severity of water loss and the boiler design. Without the water to surround the crown sheet over the firebox the exposed metal reaches such an extreme temperature that the tensile strength decreases to dangerously low point and fails.

In a fire-tube boiler, a low water condition will expose the tubes to high temperature gases, expanding the tubes to such a great extent that they will break the rolled in seat with the tube sheet. Leaks can be detected as a result of this expansion and may even result in the tubes collapsing.

Regardless of the boiler design, it is obvious that low water is a situation that must be avoided at all costs. Anthony L Kohan, author of “The Boiler Operator’s Guide”, recommends the following procedure “if water is not visible in the gauge glass because of failure of the feedwater supply…”

1. Shut off fuel to the burners.
2. Check the water level by trying the try cocks and water-column drain. If definite low water is indicated below the gauge-glass level, close the main steam valve and feedwater valve.
3. If the boiler is equipped with one, open the superheater drain.
4. Continue operating forced-draft and induced-draft fans until boiler cools gradually.
5. Let the pressure reduce gradually and when the furnace area is sufficiently cooled, check for leaking tubes and other signs of over-heating damage. On firetube boilers, look for cracked or wrapped tube sheets, broken and leaking stay bolts in the water legs. On scotch marine boilers, check for cracked or leaking furnace-to-tube sheet welds. On cast-iron boilers, look for cracked sections. On steel boilers, check for leaking joints on longitudinal or circumferential welds or riveted joints.
6. If no leakage is evident, give the boiler a hydrostatic test of 1-1/2 times the allowable working pressure. Then again check for leak-age at all critical parts of the boiler. If leakage is observed during the initial check or during the hydrostatic test, notify the authorized boiler inspector immediately so that she or he can inspect the boiler and advise on permissible repairs.

Some things never change. Prices keep going up, energy efficiencies need to be improved and air quality is an on-going issue. None of these are new problems, today’s boiler owners struggle with the same problems as their Great Grand-Fathers did. 

Don’t believe me? Well check out this ad from the Kewanee Boiler Company from 1917. The message is the same; only today’s ad would have been gender correct!
 

Boiler Horsepower

The term Horsepower is attributed to James Watt, the inventor of the steam engine (and the term “Watt” as a unit of power) as a way to help sell his engines. Watt knew he had to have a way to communicate the power of his steam engines and the best way was to equate it the most common form of power at the time - the horse which his engines would replace.

He noted that horses were typically used in grinding mills where they would walk in a 24 foot diameter circle (75.4 feet circumference).  He estimated that the typical horse pulled with the equivalent force of 180 pounds and further observed that the horse would make 144 trips around the circle in an hour or 2.4 laps per minute. This means that the horse traveled at a speed of 180.96 feet per minute. Rounding up to 181 feet per minute and multiplying that by 180 pounds of force he arrived at 32,580 ft-lbs./minute which was rounded up to 33,000 ft-lbs./minute or 1 Horsepower.

Boiler Horsepower was calculated in a much different manner. Prior to 1876 Boiler Horsepower was based upon the heating area of a boiler with every 10 square foot of heating surface equaling 1 boiler horsepower. This would mean that a boiler with 200 square feet of heating surface would be rated at 20 boiler horsepower. Not a very exact way to measure the output of a boiler to say the least, especially given the different designs and efficiencies of boilers available.

All this changed at the 1876 Centennial Exhibition held in Philadelphia, PA. There judges decided to use “developed horsepower” which they defined as the ability to turn 30 pounds of 100 degree  F feedwater per hour into steam at 70 psi. In 1884, ASME defined Boiler Horsepower as the amount of power required to convert 34.5 pounds of water per hour from feedwater at 212 degree F to dry, saturated steam at the same temperature. Today 1 boiler horsepower is equal to 33,475 Btu/Hour which is the amount of energy required to evaporate 34.5 pounds of water at 212 degree F in one hour.

blowerwheel.pdf

THREE WAYS TO FIND THE CORRECT KEWANEE BLOWER WHEEL
One of the most common requests made of our parts department is the identification, pricing and availability of Kewanee Blower Wheels. Since Kewanee has been out of business for quite some time, finding these wheels can be a bit of a challenge. There are three ways to find the correct blower wheel.

1. The best way to identify exactly what blower wheel is needed is through the original part number. With this key piece of information there is no doubt what wheel is needed. But, as we have often seen, these numbers, along with most of the boiler documentation, is long gone.
2. The second method is to trace back through the Sales Order Number. This number is located on the front nameplate of the boiler and is a six digit number. By referring to the Sales Order number often times we can determine what was originally supplied through old records. Prior to 1965, Sales Order Numbers were in the 900,000 series. These records are harder to find and we would guess that if your Kewanee Boiler is older than 1965, we will need to use another method to pin point your blower wheel.
3. The third option to locating the correct blower wheel is to physically measure the existing wheel and fill out a Blower Wheel Dimension sheet. This allows us to compare what you have against what is available. We have included a copy of this sheet below.

blowerwheel.pdf

Ask all Kewanee Boiler Questions here.  If you are looking for parts, please provide the SO# or the Sales Order Number of your boiler.

TESTING THE LOW WATER CUT-OFF

As mentioned in a previous post, one of the most important safety controls on a boiler is the Low Water Cut-off of which there are two on a boiler. Both the primary and the auxiliary LWCO need to be tested on a regular basis to keep your boiler operating in a safe manner.

Here is a procedure our service techs use to check Low water cut-off’s -

1. Blow down the water column and observe that the water level in the sight glass returns quickly.
2. Confirm that the shunt switches are working properly.
3.  Place the boiler control in manual and set the firing rate at a minimum.
4.  Observe the water level in the sight glass.
5.  Close the feedwater valve to the boiler in order to generate a slow drain condition.
6. Confirm that the feedwater pump re-circulation line is in place and operational, so that the pump will not dead head.
7. While the boiler is operating, observe the water in the sight glass noting where the first LWCO shuts the boiler off. Make sure the water level does not leave the sight glass.
8. Open the feedwater valve to the boiler in order to establish a normal operating condition.
9. Again, observe the water level in the sight glass.
10. Override the first LWCO, take note of the water level in the sight glass, and operate until the second LWCO shuts the boiler off. Remember; do not let the water level leave the sight glass. 
11. Open the feedwater valve to the boiler in order to establish a normal operating condition.
12. Reset the second LWCO.

We also replace the low water cut-off gaskets as part of our standard maintenance procedure. In fact we include these with many of our gasket kits that we provide for boilers.