Why is WHB important for energy recovery?

A Waste Heat Boiler (WHB) is an industrial device that collects and utilises waste heat generated during production processes. The WHB converts high temperature flue gases into steam that can be used for electricity generation or as process heat. The technology is an essential part of energy-efficient industry, reducing energy consumption and significantly improving the overall efficiency of processes.

What is WHB and why is it important for energy recovery?

Waste Heat Boiler means a waste heat boiler that collects excess heat energy generated during industrial processes and converts it into a usable form. WHB technology is based on heat transfer, where high temperature flue gases transfer their energy to a water pipeline to produce steam.

WHB's central importance in energy recovery processes relates to its ability to harness energy that would otherwise be wasted. Industrial processes, such as smelting, generate large quantities of high temperature flue gases. Without the WHB system, this energy would be released into the environment unused.

Technology is essential for improving energy efficiency in industry, as it enables processes to become more energy self-sufficient. A WHB system can provide a significant proportion of the steam energy required by a plant, reducing dependence on external energy sources and improving the economic viability of processes.

How does the WHB system work in practice in materials handling?

The WHB system works by collecting the high-temperature flue gases from material handling processes and passing them through heat exchangers. The system's water piping absorbs thermal energy from the flue gases, turning water into steam and cooling the flue gases to a controlled temperature.

The scheme technical components include water piping, steam collector, feed water system and ductwork for flue gas control. The water piping is positioned along the flue gas flow path for maximum heat transfer efficiency.

The process cycle starts when high temperature flue gases flow through the WHB. The flue gases transfer their thermal energy through the walls of the water pipe to the water, which vaporises. The resulting steam is collected and directed to applications such as electrical generators or other processes. At the same time, the flue gases cool down, releasing dust particles that stick to the surfaces of the water pipes.

The energy transfer process is based on convection and radiative heat transfer. The positioning of the WHB in the material handling system is critical, as it must be close enough to the heat source to minimise energy losses, but at the same time at a safe distance to allow for maintenance operations.

What benefits does WHB bring to industrial energy efficiency?

WHB significantly reduces the overall energy consumption of an industrial plant by using waste heat for steam generation. The system can cover a large part of the plant's steam demand, reducing the need for conventional boilers and fuel consumption accordingly.

Reducing energy consumption is achieved when the WHB produces steam without any additional fuel. This improves the energy efficiency of the plant and reduces operating costs in the long term. The cost savings result from lower fuel consumption and reduced need to purchase electricity.

Reducing the environmental impact is a major benefit, as WHB reduces carbon dioxide and other flue gas emissions. The system also lowers the temperature of the flue gases, which reduces the heat load on the environment.

The improvement in productivity is reflected in a more stable energy supply and reduced dependence on external energy suppliers. Process optimisation will be improved through better control of energy quality and availability. The WHB system also removes dust particles from flue gases, improving downstream processing conditions and reducing the need for maintenance of other equipment.

What factors influence the effectiveness of the WHB system?

The efficiency of a WHB system is primarily determined by the temperature difference between the flue gases and the supply water. A higher temperature difference allows for more efficient heat transfer and higher steam production. Optimal operation requires a sufficiently high flue gas temperature at the inlet to the system.

Material properties have a significant impact on system performance. The composition of the flue gases, in particular the dust content and chemical composition, determines the efficiency of heat transfer and the rate of fouling of the pipework. Corrosive substances can degrade system performance and shorten system lifetime.

System sizing is a critical factor in determining the ability of the WHB to efficiently handle flue gas flows. A system that is too small will not make full use of the available heat energy, while a system that is too large will incur unnecessary investment costs.

Optimisation of flow rates affects the efficiency of heat transfer. The flow rate of the flue gases should be adjusted so that the heat transfer time is sufficient but the back pressure does not become too high. The internal flow dynamics of the water pipe system affect the uniformity and quality of steam production.

When is a WHB investment worthwhile for an industrial company?

WHB investment pays off when an industrial plant is constantly generating large quantities of high-temperature flue gases and at the same time requires significant amounts of steam energy. The investment is economically justified when the potential energy savings are high enough to cover the acquisition costs within a reasonable time frame.

Evaluation criteria the temperature and flow rate of the flue gases, the current energy consumption for steam production and the energy price level. Typically, the investment is profitable when the flue gases are above 400°C and in sufficient quantity for continuous utilisation.

Repayment periods usually vary from three to seven years, depending on the energy consumption of the installation and local energy prices. Shorter payback periods are possible for plants with high steam consumption and expensive conventional energy production.

Long-term benefits include not only cost savings but also improved energy security and the achievement of environmental objectives. The WHB system improves the competitiveness of the plant through lower energy costs and more environmentally friendly operation. The investment is particularly attractive when a company is seeking to increase energy independence or obtain environmental certifications.