Energy efficient heating systems in industry and production
Many industrial production processes and methods require large quantities of process heat. Comprehensive energy optimisation of their heating system can considerably reduce energy consumption and costs for combustion plants, on average by 15%. Such energy efficiency measures are highly cost-effective and bring a return on investment in one to four years.
Needs are many: process heat can be generated via different energy sources, including renewables; it is required at very different pressures and temperatures; it can be transported via warm water, steam and hot air.
Optimising the complete heating system is essential when carrying out energy efficiency measures. This is because the greatest increases in energy efficiency can be achieved by matching all the components to one another and optimising the plant’s control systems.
The first step should be to perform a detailed analysis of the system’s energy consumption, its heating demand and its individual system components.
Then the energy efficiency of the individual components should be checked so that any old components, such as burners, can be replaced if necessary.
Further savings can be achieved by optimising the combustion plant’s control systems.
When constructing new systems, attention should thus be paid from the outset to the energy efficiency of the components and of the overall system.
1. Minimise demand and losses
Before optimising the individual components of a heating system, heating demand and losses should first be minimised. Efficiency can be raised by 10-15% just by using warm water instead of steam. In many cases, this makes it possible to use heat recovery and cogeneration, thus to cut energy demand further. Moreover, the thermal insulation on heat generators, pipe work and any heat stores should be checked and, if necessary, repaired.
2. Use heat recovery
Heat recovery measures maximise the efficiency of the overall system. But heat potential should be used locally and as directly as possible. Waste heat can then be optimally used for heating process water, water heating, preheating combustion, drying air and space heating.
3. Use energy efficient components
Even when energy efficient components are used, the goal should always be to optimise the entire system. This is achieved by effectively matching all new and existing components to one another. For example, modulating (controllable) burners may be used over extensive partial load ranges. They are substantially more efficient than burners, which are switched on and off individually. Boilers with large heat exchange areas can help reduce flue gas temperatures and energy consumption. Speed-controlled drive motors for forced-draught burners and pumps enable considerable savings in energy consumption.
4. Optimise control systems
Combustion plants should be designed based on their actual heating demand. For instance, a multi-boiler control system ensures that only the necessary number of boilers is switched on. If a flue gas sensor control system is installed, the flue gas composition can be continuously measured and its oxygen content optimised. Energy consumption can be further reduced by monitoring and controlling further combustion parameters - such as CO content, flue gas temperature, soot index or combustion chamber pressure - and by installing automatic flue gas or combustion dampers.