BOILERS, PUMPS & VALVES
HOW TO INCREASE FIRETUBE BOILER EFFICIENCY BY 45% OR MORE
There’s no denying that process heating systems are large consumers of energy. With sky high energy prices to contend with and Net Zero on the horizon, efforts to reduce energy consumption, improve efficiency and reduce emissions are centre stage. When it comes to Firetube boilers,
manufacturers of these systems have been working hard to improve overall efficiency and control of boilers and burners. Etienne Fourie, technical sales manager, Babcock Wanson, looks at the key developments that, combined, could increase your Firetube boiler efficiency by 45%
VARIABLE SPEED DRIVE Electric motors used on boiler feed pump and combustion air blowers traditionally operate at a constant speed. However, boilers are rarely operated continually at full capacity, so maintaining the motor at the same speed at all times is wasteful. Where process load demands are variable, motors can be fitted with a variable speed drive (VSD) which can increase efficiency by up to 30% (based in reduced electrical consumption). A VSD is an electronic device used to adjust the rotation speed of an electric motor according to the needs of the application. In a Firetube boiler they can be used to vary the pump or fan speed according to demand, ramping up or down the frequency and voltage to the motor, reducing overall energy consumption. A further benefit to be had from the use of a VSD is equipment longevity. The inherent soft- start function of a VSD means the motor starting current can be reduced, which decreases thermal and mechanical stresses.
FLUE GAS & CONDENSING ECONOMISERS Economisers are essentially heat exchange devices that extract the residual heat from the exhaust gas generated by the combustion process. That recovered heat is usually fed back into the process, typically to the boiler feed water, thereby optimising the overall efficiency of the plant in the most compact and cost-effective manner. By using economisers, you can expect to
increase efficiency of your Firetube boiler by 15-20%. Babcock Wanson offers a broad range of exhaust gas economisers perfectly matched to the boiler to which they will be fitted, incorporating ultra-robust extended surface tubes, which ensure the best practicable heat transfer and allow boiler thermal efficiencies of 98% and greater to be achieved. So efficient are they, that the return on investment can be as little as a single year. Different types of economisers are available to
meet a wide variety of processes and site needs, including economisers that can be mounted in a drawer in the back box of the boiler and those
www.essmag.co.uk losses incurred by continual stop/start cycles.
O2/CO TRIM Variable environment conditions, such as air temperature and humidity, as well as fuel quality fluctuations, have negative effects on
“By using economisers, you can expect to increase efficiency of your Firetube boiler by 15-20%. Babcock Wanson offers a broad range of exhaust gas economisers perfectly matched to the boiler to which they will be fitted”
suitable for mounting in casing on the smoke outlet, plus economisers with feed water exchanger, and those that come with fumes/ water/combustion air exchanger.
MICRO MODULATING BURNER By swapping to one of the latest generation of micro- modulating burners you can improve operational efficiency of a Firetube boiler by 5%. Traditional burners are often imprecise and not well matched with the boiler. The new style micro-modulating burners, such as our Optimo range, achieve very accurate control of low excess air levels throughout the turndown range, resulting in an excellent combustion efficiency no matter what the process load. Furthermore, the latest burners have been
designed with a very high turndown ratio, enabling the burner to adjust its output to meet the needs of the process. This avoids the costly energy
the combustion process, efficiency and emissions. Not enough, or too much, air leads to the risk of CO production. Too much air also reduces efficiency. To protect against climatic variations, burner settings are usually done with air excess at 5-8%. Efficiency can be increased by 0.9% by incorporating
O2 control and CO measurement equipment. A combined probe measures the residual O2 and the CO level in the flue gas and communicates
the information to the O2 and CO transmitter. This sends a correction 4-20 mA signal to
the BMS in order to adjust the combustion air damper position, or combustion air fan inverter speed. This makes for optimal excess air, ensuring complete combustion.
Babcock Wanson T: 020 8953 7111
www.babcock-wanson.com
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