The cost of energy has a significant impact on the competitiveness of any manufacturing company. This is especially true for those that use furnace equipment.
It should be noted that energy consumption largely depends on the physical condition of the thermal equipment and its operating mode. Naturally, it is difficult to talk about energy efficiency if the lining or heating elements of furnaces are significantly worn out, which means frequent shutdowns for repairs, or if they are regularly underloaded. Rather, it is worth raising the issue of a complete renewal of the thermal equipment fleet or its deep modernization.
At the same time, it is necessary that the new thermal equipment is characterized by energy efficiency, which is achieved by using modern technologies, and performance that corresponds to optimal production volumes. For electric furnaces, for example, the nominal efficiency, taking into account the type of furnace and the type of heat treatment, can be in the range of 40 to 70%. Depending on the characteristics of the equipment and its operating mode, it pays for itself in 10 months to 2 years, or even sooner, taking into account the reduction in repair costs.
Undoubtedly, the energy efficiency of electrothermal units is maintained by regular maintenance, as any problems with the furnace components or control system lead to energy overruns, unplanned repairs, and production defects.

Reducing energy consumption also depends on the proper organization of the production process, which involves maximizing furnace utilization and eliminating hot downtime.

What does the modernization of thermal equipment entail?

The equipment modernization is designed to increase the company’s productivity and improve the quality of its products, increase the energy efficiency of production processes, and improve working conditions. To this end, some changes may be made to the design of the furnace, which can significantly expand its operational and production capabilities.
Depending on the characteristics and condition of the equipment, the modernization can be partial or complete. At the same time, significant energy savings can be achieved without significant costs:

• by utilizing at least 70% of the furnace volume;
• by optimizing the operation schedule of thermal equipment;
• by controlling electricity consumption;
• ensuring the tightness of technological openings;
• using secondary energy resources, in the form of hot water, hot air or exhaust gases.

Partial modernization, which does not require particularly high costs, may include

• replacement of insulation and lining with more efficient modern materials;
• installation of a new gas burner system;
• replacement of electric heating elements with products of a different design or made of different materials.

Deep modernization, which requires more significant costs, involves

• use of low-inertia insulation materials with low thermal conductivity;
• Reducing the thermal mass of the equipment by means of loading equipment, tools used, ensuring faster loading, and automating processes;
• organization of internal recuperation, by organizing flue gas inflows and cages;
• ensuring better sealing of the furnace working space;
• reconstruction of heating elements and possible use of forced convection for rational power distribution in the working space of thermal equipment;
• application of an electronic control system;
• replacement of air with protective atmospheres at heating temperatures above 600 degrees, which reduces or eliminates energy losses during descaling;
• use of more efficient energy combustion systems that use combustion air heated by the heat of the exhaust gases;
• conversion of gas furnaces to electric power.

Energy consumption can also be significantly reduced by switching to low-tonnage thermal equipment that can be modularized and used for various purposes.
These measures can significantly reduce the furnace heating time, which saves energy by up to 20-60%, reduce heat losses and the power of service equipment, reduce the time for possible repairs and maintenance, and increase the productivity of thermal equipment.
The level of the lining layer plays an equally important role in energy saving. The use of low-inertia materials can significantly reduce heat loss and furnace heating costs, simplify lining installation and its weight, as well as the dimensions of thermal equipment.
The use of low-inertia materials for lining makes it possible to save energy up to 40% in batch equipment and up to 25% in continuously operating furnaces.
As for electric heating elements, it is recommended to use nichrome products that are resistant to particularly high temperatures and maintainability. But, in some cases, it will be enough to change the wire diameter or the connection scheme of the elements.
The heat of the exhaust gases can be used for space heating and water heating, and the gases themselves can be used as an energy carrier for other thermal equipment with a lower operating temperature.
In the overall balance, the use of waste gas heat can reduce heat losses by up to 50-60%.

The main problems that arise when raising the issue of modernization include the time it takes to prepare a project, which can be up to six months, and the lack of criteria for assessing the competitiveness of proposals. Today, projects with lower costs are mostly preferred. However, they may, for example, involve the use of lining materials that were relevant 20 years ago. Therefore, the modernization of heat treatment equipment should be entrusted to competent specialists who can offer a comprehensive and reasoned solution for updating the furnace fleet.