Adrian Langford is General Manager of the Process Burner Division at Lanemark International Ltd. who have been at the forefront of process gas burner design and installation since the early 1980s. He believes there are a number of steps that could be considered and taken – either via converting existing ‘point of use’ systems or replacing centralised facilities – which can help to mitigate against the new energy cost environment in which, he says, UK manufacturing must now operate. The rapid increase in energy prices is exercising minds both in the home and in the factory. On the domestic front the consistent suggestion from the media is to ‘shop around’ to ensure that the price paid for each kW of gas and electricity consumed is reduced to the minimum possible. Sensible advice, but while this pursuit of the best energy deal can lead to reductions in the amount of money that has to be spent, in industry it is only part of the story. Here, the real key is to reduce the total number of kWh that are used in manufacturing applications by critically appraising existing process heating methods in order to maximise operating efficiencies while, at the same time, identifying the optimum energy source for each process.
Where practical, the application of ‘point of use’ heating systems will offer the greatest efficiency. When the inefficiencies of boiler fed arrangements are compared and analysed against alternative, modern direct heating systems it is almost always the case that the technology now available can substantially reduce energy consumption. At the same time, benefits such as close and responsive temperature control can be realised.
The use of older, indirect gas or oil fired heat exchangers, installed in applications such as industrial process air heaters, should also be reviewed to see whether direct heated options now exist. The recent development of ‘clean burning’ natural gas direct fired combustion systems, for example, has opened up significant new opportunities in this regard.
The choice between electrically heated solutions and direct gas fired alternatives should also be considered. Although it is not an overstatement to claim that both gas and electricity prices have rocketed upwards in recent months, average non-domestic gas prices per kWh remain at approximately one third of the equivalent non-domestic electricity prices. This wide difference can completely offset the low capital cost and high operating efficiency advantages often associated with
electrical heating systems. As energy prices continue to rise, of course, this gap – between gas and electricity prices – will continue to widen.
It is this scenario which compels minds in industry to assess the potential benefits of using gas as a heating source. Comparisons of the investment required to change from electricity to gas, or to upgrade an existing gas-based heating system, can often see the ‘project payback’ equation moving into the black at a relatively early stage. Moreover, the payback period associated with the capital expenditure required to carry out modifications to process plant will be significantly shortened every time the gas/electricity differential increases.
Happily, for much of industry, help arising from the Government’s commitment to maximising energy efficiency is now available in the shape of the Carbon Trust which can facilitate capital projects where reductions in energy usage can be demonstrated. Subject to eligibility and regional variations, the Carbon Trust focuses in particular on providing interest free loans to – “Small or medium-sized enterprises (SMEs) in England and Scotland, or all businesses in Wales that have been trading for at least 12 months”.
Perhaps reflecting the importance of the issue, the limit for such loans has recently been doubled to £200,000 while the scheme also now permits equipment suppliers to make energy efficiency loan applications on behalf of a customer. This clearly enables the full benefit of the manufacturer’s expertise and capability to be enjoyed right from the start of the process.
The loans themselves are unsecured, interest free, repayable over a period of up to four years, incur no arrangement fees and the application process is straightforward. In Northern Ireland, where all businesses that have been trading for at least 12 months may be eligible to apply for an unsecured
interest free loan of up to £400,000, the scheme is even more attractive.
In general terms, the Carbon Trust defines eligible businesses as being those in the private sector that have been trading for at least 12 months, have an acceptable credit rating and fall within the definition of an SME in England or Scotland and any business in Wales or Northern Ireland.
The definition of an SME is therefore critical and applicants should note that it has been defined by the EU as being an enterprise with –
* Less than 250 full time equivalent employees
* Less than €50m turnover and/or
* Less than €43m assets
* Having no controlling interest of more than 25% by a non-SME (i.e. it must not be part of a larger organisation)
The Carbon Trust website – www.carbontrust.co.uk/energy/takingaction/loans.htm – provides a simple calculator which will indicate the likely loan amount that could be made available. This is based on a comparison between the annual energy usage (by fuel) of existing heating system(s) and the anticipated annual energy usage ‘post project’ (by fuel). Each energy source has a ‘carbon conversion factor’ expressed in kgC/kWh and, coincidentally, the carbon conversion factor for natural gas is just over one third of that of electricity, providing the greatest scope for support from the scheme. Calculations can also be made for modifications to existing systems not requiring a change in energy source.
In many cases, the start point for the changeover or upgrading process can be the assessment of the energy usage of existing equipment, which can often be achieved by the installation of energy metering facilities.
At Lanemark, this is an issue to which we have paid close attention with the firm belief that, logically, the process should begin with the measurement of existing gas or electricity consumption of individual items of plant. This is particularly significant when ‘point of use’ process heating is to be adopted in place of previously centralised facilities.
In the case of gas, this can be achieved by the installation of compact gas flow meters which can be easily fitted into an existing supply pipework – examples include the DM (mechanical) and DE (electronic) ranges manufactured by Elster Kromschroder GmbH. These can operate in gas supply pipes from 1" diameter upwards, with either screwed or flanged connections and associated isolation valves used as required. Both types permit either the direct reading or transmission of pulse outputs to remote data recorders.
As indicated earlier, one of the key areas where energy saving opportunities often arise is via the conversion of a centralised boiler fed or indirect oil or gas fired system to direct gas firing. Typically, an indirect fired air heater supplies hot air to a process oven or dryer at an efficiency level of 70 – 75%, while in comparison, modern direct fired gas burner technology will achieve efficiency levels in excess of 90%. This clearly represents an energy saving potential of some 20%.
Conventionally, indirect process air heating methods have been used where the products of combustion from the burner equipment must not come into contact with the product to be dried or cured. This has been particularly important in an oil fired system where clean combustion has been an unachievable goal. However, the latest developments in gas burner technology now allow the use of direct fired burner systems for an increasing number of applications, primarily because the
emissions of CO/NOx have fallen dramatically.
Another important area of energy saving potential exists on gas fired plant where the installation of modulating gas and air controls replaces outdated high/low or on/off burner control systems. The availabilty of reasonably priced motor speed controllers, for example, allows burner manufacturers to offer a dual energy saving by reducing the speed of combustion air fans in direct response to signals (typically 0 – 10 VDC or 4 – 20 mA) from oven temperature control systems.
The latest gas valve control systems can react directly to the changes in air pressure produced by the combustion air fans and accurately increase or decrease the volume of gas used by burners. Plant operators benefit in three ways from this development.
Firstly, through a reduction in electrical energy consumed by combustion air fans, secondly, by enjoying the advantage of ‘on ratio’ combustion – that is to say the reduction in wasted excess air which thereby maximises burner efficiency and minimises harmful emissions and, thirdly, via accurate system temperature control. The emphasis on the need to maximise energy efficiency throughout industry is now firmly with us and we can reasonably expect that, henceforth, this will always be the case. Accurate means of measuring fuel usage, significant steps forward in gas burner technology and the availability of financial support and incentives, all come into the spotlight in this context and each can contribute towards maximising process efficiencies and minimising energy consumption. From an investment and production quality point of view, there are steps that can be taken in this scenario which have much to offer. Perhaps today, more than ever before, they represent means to sustain and develop business from which much of manufacturing and engineering in the UK could benefit.
FOR ALL YOUR PROCESS GAS BURNER NEEDS!
