Energy efficiency has become a distinguishing factor when selecting boiler for an industrial application.
Considering that manufacturers are only required to prove that their products conform to the maximum continuous rating (MCR), it begs the question, how many actually offer efficiency?
While the environmental discussion has had a slower offtake in Africa than in the rest of the world, where reducing carbon emissions is a definite business imperative, the pending carbon tax is going to hit South Africa hard. The premise of this move by the government is simple – to tax direct emissions associated with business activities. Practically, this means any company emitting greenhouse gas will have to pay up and, secondly, the cost of electricity will be higher. Making a good quality boiler is no longer the differentiating factor.
Fig. 1: Industrial steam generator boiler (Garioni Naval).
Cost is a factor and natural gas not only delivers the efficiency, but is also cheaper overall. The Combustion Technology team have proven this time and time again. A local packaging company embarked on an aggressive programme to reduce its carbon emissions and carbon footprint by installing two new gas-fired boilers and converting two existing coal-fired boilers to natural gas-fired. The resultant reduction in energy usage was amazing and the coal boiler efficiency increased dramatically, from around 70% to consistently running between 80 to 83% on natural gas. Production energy usage improved from between 175 and 154 MJ/HI to 105 and 99 MJ/HI on natural gas.
Coal is often chosen based on an initial cost estimation, but with gas don’t only save in terms of emissions, but on a number of other aspects including electrical power, labour, cleaning and maintenance. Gas, while more expensive per energy unit, brings an overall cost saving to the project. With coal at best only using 70% of the energy compared with gas-fired boilers where 90% energy use is guaranteed, less gas is also needed to deliver the same amount of energy. Savings are critical, considering the sheer cost of running a boiler plant.
Fig. 2: Typical monitoring equipment (Autoflame).
The downstream benefits of having better quality steam and improved reliability in their boiler operations also result in better overall plant productivity. At face value, one could argue that, if the boiler is already 90% efficient, how could it be improved effectively by any more than 10%? The secret is linked to companies’ downstream processes and making sure that the boilers adapt and are set up correctly for particular processes. It is then a matter of ensuring that emissions stay within the set limits, thereby achieving practical efficiency.
With gas offering very real fuel savings, and considering that it stands a very good chance of being exempt from the carbon tax, it is the way of the future. Ironically, the biggest complaint about gas from companies is usually the price. The trick in all of this, however, is to reduce the energy consumption and fuel usage by being more efficient.
Continuous monitoring essential
Monitoring systems can be challenging in the automated world with clever machines that no longer require people to be present. With much trust placed in automated systems, it is easy to forget that these are just machines after all. Boiler management services are critical in this environment, providing, in real-time, much-needed monitoring which is vital to understand how any given boiler in a plant is performing.
Fig. 3: Typical exhaust gas analyser (Autoflame).
For optimum efficiency, you must know what is going on in the boiler house at all times. Combustion Technology’s management systems provide the necessary data, monitoring of fuel usage and emissions, as well as all boiler and burner functions, water levels and temperature, and pressure for example.
Installing a management system brings further fuel bill savings thanks to the ability of such a system to read O2, CO and CO2 emissions. This enables the user to know immediately when fuel is being wasted, but also to track where and when any problems arise. In addition, it is critical to monitor the changing ambient conditions, varying CVs and the conditioning of fuel.
Contact Grant Renecle, Combustion Technology, Tel 021 715-3171, Email
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