When looking at boosting efficiency in the boiler room it’s more than just saving fuel and electrical costs because there are other impact areas that greatly affect the cost of operation, and must be looked at collectively. The areas are efficiency, reliability, and safety.
Efficiency in a boiler relates to the cost of fuel being burned in it, and how much of it is transferred to the water within to make steam or hot water for heating the building. We’ll be focusing on steam generation or in other words, its fuel to steam efficiency, and how effectively the burner and boiler are working together to produce the optimum.
Maintaining Good Boiler Room Efficiency
1. Efficiency in the boiler itself starts with an excellent water treatment program and one which is followed diligently on a daily basis. A reputable water treatment consultant will guide the operator in what has to be monitored and adjusted on a routine basis in order for the boiler to operate most efficiently. This means making sure the water softener is working properly, limiting the calcium and magnesium within the feed water from forming scale and binding to the heat transfer surfaces of the boiler. Remember, as little as 1/16” of scale can result in a 15% increase in the fuel spend!
2. The other consideration with a sound water treatment program is controlling the Totally Dissolved Solids (TDS levels) in the boiler. These visually transparent elements will not only add to the scale problem but most importantly, will cause erratic or bouncing water levels resulting in nuisance shutdowns followed by energy-wasting pre and post-purge losses.
3. When addressing scale formation the best way to determine if this is becoming a problem is by routinely monitoring the boiler’s stack temperature. When seeing an increase of 40 Deg. F over the benchmarked operating pressure, firing rate, and ambient temperature in the boiler room, there is a 1% loss in efficiency, and most probably the cause is scale on the boiler tubes or soot deposits on these transfer surfaces due to poor combustion.
4. Another key monitoring point when considering the boiler’s efficiency is the feedwater temperature entering the boiler. If the feed water is being supplied from an atmospheric receiver, the temperature is probably in the 180 Deg. F. range. If it’s coming from a deaerator, and operating at 10#, it’s about 239 Deg. F. The point is if that temperature entering the boiler is 10 degrees less, you’ve lost 1% in efficiency. Monitor and take appropriate action!
5. Also at this point, consider returning as much hot condensate as possible thereby reducing venting while returning the condensate to the deaerator or a high-pressure receiver. Now, for every 10 degrees of increase returned, it’s 1% savings!
6. Routine boiler tune-ups using a qualified and trained technician will assure the boiler and associated equipment is running as efficiently as possible or they can make the proper suggestions for making it so.
When looking at the cost of operation saving opportunities, and viewing them through the lens of reliability, it starts with maintaining a clean and orderly boiler room. One with organized records containing:
7. The Boiler Room Log including daily, weekly, monthly, and bi-monthly entries.
8. The Water Treatment Log
9. Service and maintenance reports
10. Boiler and accessory operating manuals
11. Key contacts handy for equipment training and service.
Of all these, the Boiler Room Log is the key essential in adding to increased boiler uptime and efficient operation as it calls for logging many key essentials including the following:
12. Monitoring feed water temperature will not only save energy but lessen the chance of thermal shock causing boiler downtime repair costs and loss of production.
13. Monitoring stack temperature can not only save energy but also prevent boiler downtime due to pressure vessel failure because of heavy scale deposits as indicated by temperatures elevating beyond normal. Again, more production losses and added repair costs.
14. Routine bottom blowdown of the boiler according to the manufacturer’s instructions can save on possible downtime due to sludge and scale accumulation and resultant pressure vessel failure. This blowdown water cannot be used because of excessive contamination, but must be cooled through a separator and dumped to drain. However, the TDS water because it is much cleaner and more continuous can be sent to a heat reclaim exchanger, transferring heat to the boiler’s feed water supply. Every 10 degrees, 1% fuel savings.
15. Monitoring and regularly blowing down the boiler’s water column(s) while before noticing the level in the gauge glass ensuring it is stable and not bouncing. This bouncing will lead to costly nuisance shutdowns.
16. Monitor the boiler’s support accessories including the softener, chemical feed system, boiler feed system, and associated pumps for proper levels, temperatures, and pressures. Failure of this equipment leads to costly downtime.
This is the last facet through which we view lowering the cost of operation in the boiler room, and it’s so important because these factors do not only impact operational cost, but also those costs associated with property, life, and limb.
A boiler can be a dangerous piece of equipment if it is not understood and respected. Operating it properly requires training and support from qualified individuals who not only appreciate the workings of the equipment but the hazards too. Just a few items of extreme importance.
17. Electrical: Boilers and its supporting accessories use high voltages, and power which has been transformed down to operate control circuits, etc. A procedure needs to be documented to assure safety when working around this equipment to avoid burns and electrocution.
18. Water Column: The water column is one of the most important controls on the boiler because if it fails and the water level in the boiler falls below its safe operating point without turning the feed pump on, the boiler can have a massive occurrence destroying everything in its path. It’s termed a waterside explosion. As such, it is recommended that at least once a month an evaporation test be conducted, securing the feed water, and watching the boiler’s gauge glass to assure the low water cutoff shuts off the boiler/burner at the appropriate time. If not, the boiler must be secured and the remedy applied.
19. Safety Valve Piping: The safety valve piping must have proper venting and a place for safe discharge should the valve(s) unexpectedly relieve. Again, the cost may be life and limb as temperatures expelled are very high, ever-increasing with operating pressures.
20. Confined Space: Often repair or inspection of a boiler requires a person to enter the furnace or drum. Proper safety procedures will ensure the safety of the service person.
A procedure has to be documented and followed to prevent this needless and possibly tragic cost from occurring.
Boosting efficiency in the boiler room is a very important part of reducing the overall cost of operation. Those that manage and operate the boiler equipment should be properly trained and supported by the best available technical professionals in the area.