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Heat Recovery From Industrial Processes

The Organic Rankine Cycle, for its intrinsical characteristics – first of all, the low temperature required for operation – is optimally suited to be used as the basis for heat recovery systems, designed to turn uselessly wasted heat into a valuable resource.

Zuccato Energia ORC systems are able to recover waste heat from most industrial systems involving heat, such as:

  • Ovens, kilns and furnaces in metal, glass, ceramic and concrete industry;
  • Boilers and steam generators in paper,chemical, and petrolchemical industry;
  • Ovens, dessicators, smokehouses and frying vats in food industry as well as incinerators in animal fat rendering.

The small dimensions and power rating of Zuccato Energia ORC systems make them ideally suited for a distributed installation capable of intercepting heat right where it is generated, without any need for the costly interventions on the main systems required by large-scale plants. This simplifies retrofitting existing plants as well as increasing plant reliability. It also allows unparalleled heat recovery efficiency as it becomes possible to install on each heat dispersion point the most suitable ORC module to recover that specific type and quantity of waste heat .


The most common interface method involves placing fume-to-water heat exchangers in the flue gas circuit of the plant, but there ore other possibilities as well, and the use of water in a closed loop as vector fluid ensures efficiency, safety and simple engineering.

Zuccato Energia modules are exempt from the Italian Fire Prevention Certification (CPI) as they the vector fluid is just plain water and their working fluid is neither flammable nor explosive.Where required, they can also be built in an ATEX-certified configuration.

Metalworking Industry

Metalworking industry is probably the first industry sector that comes to mind when talking about waste heat recovery and, as a matter of fact, most plants already have some kind of steam-based heat recovery system in place to recover most high-temperature heat.

ORC systems by Zuccato Energia howevewer can go one step further, giving the possibility to further increase recovery efficiency, by intercepting the medium-temperature heat still available downstream of the aforementioned recovery systems, thanks to the placement of appropriate heat exchangers in the flue gas circuit of melting or billet reheating furnaces in key locations such as:

  • Upstream of the bag filter, where power generation has the added bonus of reducing and stabilizing the temperature of gases enetering the filter.
  • Downstream of the electrostatic filter (where present), recovering heat from clean, high-temperature fumes.

The low operating temperature of the Zuccato Energia ORC system opens up further energy saving possibilities through the valorization of low-temperature waste heat that was considered unrecoverable until now, such as:

  • The heat contained in the cooling water circuit – an easy-to-implement heat recovery system that has both an economic as well as an environmental return, as it reduces the amount of heat dispersed by cooling towers in the atmosphere thanks to its conversion into electricity.
  • The heat coming from scrap metal drying ovens, usually operated at a temperature too low for steam-based plants but perfect for Zuccato Energia’s ORC modules.

Zuccato Energia can give full-service engineering support in this field too, thanks to the support of its specialized E.S.Co. partners.


Ceramic tile industry consumes and at the same time disperses huge amounts of energy.

Depending on the type of oven, up to 20% of the thermal energy input of a ceramica kiln goes is dispersed through the flue gases, up to 25% is dipersed through the kiln walls and a whopping 55% is just thrown away to cool the finished product at the end of the firing process.

Zuccato Energia can intervene on several levels to limit this waste.

  • Placing patented heat exchangers in the hottest part of the cooling stages of the kiln – thanks to a partnership with the holder of that patent – it becomes possible to recover up to 45% of the heat produced by the burners;
  • Placing a heat exchanger in the flue line upstream of the bag filter,power generation is coupled with reduction and stabilization of the temperature of flue gases entering the filter;
  • Installing a heat exchangerin the flue line downstream of the electrostatic filter, where present, makes it possible to perform high-efficiency heat recovery from clean, high temperature fumes.

Consider that enough heat can be recovered from a common 4000-kWT, 7600 kg/h tile kiln, to operate a 175-kWE ORC module by Zuccato energia, outputting more than 1GWE/year to the power grid, allowing for a very short investment payback time.

Paper Industry

The systems offered by Zuccato Energia represent an optimal solution to increase efficiency in paper mills as well.

The low operational temperature typical of Zuccato Energia ORC modules finally opens up access to the vast quantities of waste heat available in paper mills that until now were considered as unexploitable due to their low temperature.

An example of said waste heat sources are what in Italian paper mills are called fumane, i.e. the air rich in water vapour coming from the paper drying process. This is usually already collected for atmospheric disposal and as such it is relatively easy to insert a fume/water heat exchanger in the circuit to extract all possible waste heat before discharging the residue in the atmosphere.

Zuccato Energia can give 360-degree engineering support in this field as well, thanks to the support of its specialized E.S.Co. partners.


Glass industry has much in common with ceramic industry for what regards the use and dispersion of huge quantities of heat.

The Organic Rankine Cycle modules by Zuccato Energia, by recovering said waste heat as a source for the production of electricity, increase overall process efficiency and allow significant energy savings.

  • In hollow glass (bottles, drinking glasses, jars…) manufacture it is possible to intervene in different steps of the manufacturing process:
    • By recovering heat from flue gases upstream of the bag filter, with the added bonus of cooling and stabilizing filtering temperature;
    • By recovering heat downstream of the electrostatic filter, where it is possible to perform a hihly efficient heat recover from clean, relatively high temperature fumes.
  • In flat glass (e.g.window pane) manufacture, it is possible instead to recover heat from the clean airflows coming from thermal stabilization processes.

Zuccato Energia is able to give specialized engineering support in this field too, thanks to the support of its specialized E.S.Co. partners.

Petrochemical Industry

In petrochemical industry there are several processes involving a cooling step; the heat released in those steps can be advantageously recovered by one or more Zuccato Energia ORC modules which, if required, can be produced in an ATEX-certified version for use in dangerous environments.

A few examples:

  • Hydrocarbon cracking: this process involves the use of 850°C ethylene that is then quickly cooled down to 400°C to stop the reaction. This thermal drop can be used to produce steam and/or overheated water to be used to feed one or more ORC heat recovery modules;
  • Reforming: downstream of the last reactor, fluid flow is cooled and injected in a pressurized separator. This cooling step – as well as the fumes from the heating chambers of the reactors – can be used to produce hot or overheated water to be fed to one or more ORC modules;
  • Ammoxidation: In the widely-used SOHIO process to produce acrylonitrile, the reactants (propylene, ammonia, and air) are passed through a reactor containing a catalyst at 400–510 °C and 50–200 kPag and then quenched in aqueous sulfuric acid. The excess heat from this quenching step can be collected and used to feed one or more ORC modules.

Zuccato Energia, by enrolling the support of its specialized E.S.Co. partners, can give its customers complete engineering support in this field as well.

Food Industry

Food industry uses high quantities of heat, but the temperature of wasted heat is usually insufficient for traditional steam-based heat recovery systems.

This is however the arena where Zuccato Energia ORC systems operate best, recovering heat at temperatures even lower than that of boiling water and with a range of module sizes suitable even for smaller firms.

This opens up a wide range of heat recovery possibilities from multiple points of the food processing chain, from ovens to smokehouses, and from essiccators to frying vats.

The small size of Zuccato Energia ORC modules allow for an installation near waste heat production points, thus allowing maximum heat recovery efficiency , while their advanced range of technical specifications makes it possible to find ad hoc solutions for virtually any need in this sector.

Zuccato Energia, by enrolling the support of its specialized E.S.Co. partners, can give its customers complete engineering support in this field as well.