McKenzie’s Boiler Blog

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!