Improving Boiler Efficiency

With the costs of heating fuels continuing to rise, improving boiler efficiency is a prime concern of most facility managers today. When speaking of improving boiler efficiency, several basic terms regarding boiler efficiency need to be well understood. Heat Transfer Efficiency is an inherent property of boiler design, and manufacturers typically indicate the values of efficiency that the specific boiler design provides. It is simply a ratio of how much heat must be put into a system to get a given amount of heat out. It should be noted that the manufacture specifications for heat transfer efficiency for a specific boiler are for a perfectly clean system. Heat transfer efficiency loss can have a very significant impact on overall energy efficiency. ECMI helps our clients keep boilers operating at peek heat transfer efficiency by eliminating lime scale from within their boiler and other facility systems. Heat Loss Ratio is also an inherent property of boiler design. Manufacturers typically indicate the values of heat loss efficiency that the specific boiler design incurs. Improvements can most often be made, in regard to heat loss ratio efficiency, by better insulating the boiler and piping systems. Heat loss ratio is also a value of the building envelope itself, and boilers have to react in relation to how a building looses heat. Improvements in heat loss for a facility should also be looked at when considering methods to improve efficiency. Improvements include better insulating the facility, improved glazing, and better control of air-flow within, and leaving, the building. Operating Efficiency (also called seasonal efficiency) of the boiler relates to the actual and ever-changing conditions found within a facility, how the boiler reacts to the load, and the amount of fuel consumed over a period of time. This value is not generally quantified by boiler manufacturers due to the many variables involved in daily operation, and variables due to the building envelope itself. Since a boiler operates most efficiently when it runs constantly (or at full load), the trend of current technologies is to have several smaller boilers managing supply water needs instead of one large unit. This way each boiler operates closer to optimum efficiency when they are called on for heat. Boiler Efficiency Graphs & Comparisons Boiler Power Plant Efficiency Water Tube Boiler Efficiency Energy Efficiency Rate We have found that significant improvements can be achieved in boiler efficiency by better controlling how the boiler operates in response to the changing conditions of a facility, as well as managing limescale within the piping system. Combining technologies provides significant improvements in boiler power plant efficiency. Boiler Power Plant Efficiency The following Boiler Efficiency Graphs show run-time comparisons utilizing Savastat LC in a day-on, day-off test cycle over a period of seven days: You can readily see the difference in the cycle patterns during the days Savastat LC is managing the boiler, by the varying mean temperatures. Savastat LC closely manages the boiler based on actual demand. The days LC is not controlling the boiler, the firing pattern is very regimented between the boiler set point, and cut-off temperature. When we take a closer look to compare an on-day to an off-day: Here we can better see that the mean temperature is "modulating" to accordance to system demand (load), whereas the off-day maintains a consistent internal boiler temperature regardless of the heating demand. The mean temperature reduction of only a few degrees results in significant efficiency improvements, as the heat is transferred more effectively into the system at a wider differential. Holding off the boiler when heat is not needed also significantly adds to the efficiency improvements achieved. Typically a reduction in run-times of 20% or more are achieved. Facility managers can conduct similar boiler efficiency analysis by tracking boiler run-times and day degree information. Boiler Power Plant Efficiency & Limescale The following graph shows how limescale effects water tube boiler efficiency: