Boilers for metallurgy and the metalworking industry
For this industry TIPO Kotlogradnja designs and manufactures: industrial steam boilers; waste heat recovery boilers; hot water boilers.
Each boiler is designed and manufactured to the required capacity, process requirements, fuel type and operating conditions of the plant.
The role of heat and steam in metallurgy and metal processing
In this industry furnaces consume most of the energy: reheating furnaces in hot rolling, furnaces for heat treatment and annealing, and melting furnaces. Their heat also leaves through the exhaust gases, and in electric arc furnaces these gases carry a considerable amount of energy that can be used to preheat scrap, produce steam or generate electricity. A boiler does not replace a furnace: it serves auxiliary consumers and uses the heat of the furnace exhaust gases, so its role in the production chain is supplementary rather than primary.
Steam and warm or hot water are most often used in surface treatment lines. In hot-dip galvanizing the workpiece passes through several baths: degreasing in a heated alkaline solution, pickling in acid, fluxing in a heated solution and, where applicable, drying before immersion in molten zinc. Heated baths are natural consumers of steam or warm water, and in continuous hot-dip coating lines steam can also be produced from furnace waste gases.
Requirements and regulations
Heat from furnaces is not constantly available. Electric arc furnaces work in batches, so the quantity and quality of the exhaust gases change during the cycle, and recovery systems are usually designed around a single design point, which makes off-design operation difficult. A waste heat recovery boiler is therefore designed for the actual gas profile, and steam consumers need a solution for periods when the furnace is idle, for example a supplementary steam boiler. This should be defined at the start of the project, not at commissioning.
Boilers and piping are pressure equipment, so in the EU the PED 2014/68/EU and CE marking apply; see certificates and standards for an overview of standards. Plants also fall under the environmental framework: the best available techniques reference document for the ferrous metals processing industry (JRC, 2022) belongs to the Industrial Emissions Directive 2010/75/EU and covers, among other things, hot rolling and hot-dip coating, including batch galvanizing. According to a German overview of techniques, heated acid baths require extraction of vapours, and acid is heated indirectly, without direct steam injection.
Fuel, energy and sustainability
Heat recovery is common in this industry: preheating the charge or combustion air with exhaust gases, regenerative and recuperative burners and, where steam is needed, waste heat recovery boilers. Every measure involves a trade-off; preheating the air, for example, increases nitrogen oxide emissions. The right solution therefore depends on whether the plant has a steam or warm water consumer, at what intervals it must be supplied, and how heavily the furnace is loaded during a shift.
According to an IRENA overview, process heat accounts for a large share of fossil fuel use in steelmaking. Decarbonisation relies on hydrogen, electric arc furnaces running on scrap, electrification of heat and heat recovery, but many heating technologies are not yet mature for industrial use. For the boiler house this means that the energy source and configuration should be planned with the possibility of later change, including electric boilers where renewable electricity is available.
What to define when selecting a boiler
Before choosing the boiler type, two questions should be separated: how much steam or heat the consumers need and when, and how much heat the furnace actually releases and when. Only their comparison shows whether a waste heat recovery boiler is sufficient, whether an additional steam or hot water boiler is needed, or whether they should be combined. In any case the boiler house should be planned together with the process lines, not afterwards, because the position of the furnace, flue ducts and consumers determines pipe routing and available space. Details of the selection are described in the guide how to choose an industrial boiler.
- consumption profile of steam, warm or hot water per shift and per process line (baths, dryers, heating)
- characteristics of the waste heat source: furnace duty cycle, interruptions, gas composition and cleanliness
- reserve for periods when the furnace is idle and the way of supplementary firing
- feedwater treatment and condensate return
- regulations and standards (PED, CE, environmental permits) and space available next to the furnace
Boiler types for this industry
Industrial steam boilers
Saturated or superheated steam for industrial, process and power applications. Shell and water-tube boilers for solid fuel, biomass, liquid and gaseous fuel.
View →Waste heat recovery boilers
A WHRB (Waste Heat Recovery Boiler) is a steam generator that uses the waste heat of exhaust gases from industrial processes to produce saturated steam.
View →
Hot water boilers
Hot water for industrial and energy systems and district heating. Shell and water-tube boilers for all common fuels.
View →Applications
Industrial steam boilers
- Metallurgy and mining
- process heat for energy-intensive processes
- Metallurgy and mining
- process steam and hot water for energy-intensive processes
Waste heat recovery boilers
- Metallurgy
- heat from furnaces and thermal processes
Frequently asked questions
What is the difference between a shell and a water-tube steam boiler?
A shell (fire-tube) boiler has a large water content, is built to EN 12953 and suits small and medium capacities with stable operation. A water-tube boiler has a small water content, is built to EN 12952 and is used for larger capacities, higher pressures and superheated steam.
Which fuels can a TIPO Kotlogradnja steam boiler use?
Solid fuels (coal), biomass (wood chips, pellets, straw, husks), liquid and gaseous fuels (natural gas, light fuel oil, heavy fuel oil) and gas–hydrogen blends. The furnace and burners are designed for the chosen fuel.
How are the capacity and pressure of a steam boiler chosen?
From the actual steam demand profile, the pressure and temperature required at the consumers, the fuel type and the operating regime. Our engineers run a thermal calculation on the investor's data and propose the type, size and configuration.
Which standards apply to steam boilers?
EN 12953 for shell boilers, EN 12952 for water-tube boilers, EN 13445 for pressure vessels, EN 13480 for piping, and ASME BPVC or AD 2000 for export markets. Pressure equipment carries the CE mark under PED 2014/68/EU.
Can a waste heat recovery boiler work when the furnace operates intermittently?
It can, but it must be taken into account that the heat is not constantly available. In batch furnaces such as electric arc furnaces, the quantity and quality of the gases change during the cycle, and recovery systems are usually designed around a design point. The gas profile is therefore defined before the project, together with the decision whether the difference is covered by a supplementary boiler or by heat storage.
Should acid baths be heated by direct steam injection?
According to a German overview of best techniques for steel processing, direct steam injection is not recommended; acids are heated indirectly through heat exchangers. Steam or warm water can serve as the heat carrier in the exchanger, which is determined according to the type of bath and the requirements of the line.
Is preheating the charge better than producing steam from furnace waste gas?
Neither is always better; it depends on the plant. Preheating the charge or air and regenerative burners return heat directly to the furnace, while a waste heat recovery boiler makes sense when the plant has a steam or warm water consumer, for example baths or dryers. The measures can be combined, noting that air preheating increases nitrogen oxide emissions.
Standards we design and build to
TIPO Kotlogradnja designs and manufactures boilers and complete boiler plants according to the investor's requirements, fuel type, capacity and operating regime. The process covers requirement analysis, solution proposal, offer, design, material procurement, manufacturing, erection, testing and commissioning. Whatever the complexity of the project or the market, the equipment is designed and built to European and international standards, including EN 12952, EN 12953, EN 13445, EN 13480, ASME BPVC and AD 2000, in line with the project documentation and the investor's requirements.
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