Biogas, a clean and flexible energy source

Recent events and the related consequences on our economic system have highlighted how essential it is to invest in energy production from renewable sources.

The agricultural and food industry uses waste and by-products in its production cycle, but not always efficiently. With a specific plant for the treatment of biomass it is possible to produce biogas from waste and by-products, which can be used for the production of electricity and heat, therefore an additional profit for the company.

In other words, biogas production plants are very interesting systems from the point of view of a circular economy.

In the last 10 years, the number of installations in Italy has tripled, with a production of over 2.5 billion cubic meters, which makes our country the second largest producer of biogas in Europe and fourth in the world.

 

Production steps of Biogas

 

Feeding and anaerobic digestion

By-products and biomasses (slurry, manure, sorghum, triticale, corn silage, other livestock waste, or residues from the agri-food industry, etc.) are inserted daily into the digester (fermenter) in different proportions and quantities from company to company.

Ultrasound treatment

An ultrasound disintegration system helps digestion, homogenizes and stabilizes the biological and energetic properties of the biomass, allowing an increase in production yield in the fermentation process (anaerobic digestion). Furthermore, the disintegration favors the fluidization of the substrate, helping to lighten the work of the pumps and agitators of the system, considerably reducing the value of electrical absorption. The ultrasound system can be inserted both at the digester inlet and in continuous recirculation with the latter

Biogas production

Inside the digester, the bacteria produce biogas (mainly CO2 and CH4) at a controlled temperature (about 42°C) and with certain times, after which the biomass is transferred to a storage tank for a final treatment which will give rise to the digestate.

Conversion into electrical and thermal energy

The biogas produced is treated and sent to the cogenerator which produces electricity and thermal energy. The electricity is sent to the national grid, while the thermal energy can be used both to heat the digesters or for district heating.

Digestate

The residual biomass has an important value, with even better characteristics than the starting biomass. It consists of a solid and a liquid part, both of which can be used as a fertilizer.

Description of the ultrasonic disintegration system

 

With this in mind, EveryWave has designed and produced a special ultrasonic reactor which, integrated with specialized systems for shredding, pumping and process control, represents a solid and efficient technology for controlling and increasing the production yield of Biogas.

The ultrasonic reactors of the plant are charged via the system pump. The substrate is routed through the ultrasonic field with a specific flow rate, so that the ideal energy input required for the treatment is achieved.

Upstream, a shredder (optional) protects the machine from foreign objects and provides coarse mixing in order to achieve optimal ultrasound coupling. This element is essential for biomass that may contain foreign bodies or solid parts of significant size and strength.

Operating principle of the reactor

 

The disintegration and homogenization of biomass occurs due to the high levels of cavitation at very high pressure generated by ultrasound.

CAVITATION: The high frequency mechanical vibrations, generated by the sonotrodes, applied to the reaction chamber, are transferred into the biomass.

The oscillating power is transmitted through the liquid part, where, by means of a strong alternating pressure (up to 40,000 oscillations per second), infinite microscopic cavities are generated which collapse, creating shock and shear micro waves at very strong pressure and very high temperature , capable of breaking down and disintegrating the substrate.

Description of FLOW:WAVE reactors

 

The most innovative element of the treatment system is represented by the FLOW: Wave® reactor, consisting of a robust, almost maintenance-free structure for 24-hour operation.

The FLOW: WAVE® modular ultrasonic reactor consists of a sonication chamber with external ultrasonic transducers. This solves the typical problems of internal sonotrode disintegration systems (ROD type).

In fact, since biomasses with a typical solid content of 10% (and above) have a relatively high viscosity, a high effort is required to ensure an effective coupling with ultrasound.

The structure of the FLOW: WAVE® reactor prevents blockages and always maintains a high value of disintegration efficiency.

The disintegration cell is equipped with suspensions in each fixing point to cancel the vibrational dispersions and maximize the ultrasound yield.

INNOVATIVE DUAL FREQUENCY SYSTEM: The FLOW: Wave® reactor is also available in dual frequency 20 / 40KHz to ensure even more effective disintegration with different types of compounds.

PLC control

 

Finally, a PLC control system allows for robust and efficient operation.

In fact, the plant is equipped with sensors that control the temperature, pressure and volumetric flow of the biomass, as well as the management of the reactor. The pump delivery pressure and temperature parameters allow you to check its correct operation, as well as the efficiency of the biomass flowing in the treatment circuit. The instantaneous flow rate, measured at the outlet of the reactors downstream of the pump, allows to automatically adjust the power and the sonication frequency, in order to obtain an optimal fluidization.

All the data collected and the entire process management can be interfaced with the Biogas production plant according to Industry 4.0 protocols.

Advantages of the FLOW-WAVE system

 INCREASE IN THE SYSTEM'S ENERGY EFFICIENCY

Thanks to the technology of the FLOW: WAVE® system,  the biological properties and the energy qualities of the biomass are optimized, favoring an increase in the efficiency of the biogas plant or, in other words, the same yield for a lower quantity of substrate.

 REDUCTION OF FATIGUE

The ultrasonic disintegration favors the fluidification of the substrate, helping to lighten the work of pumps and agitators, increasing their life and considerably reducing their electrical absorption value.

 REPOWERING OF THE PLANT

The FLOW: Wave® technology, efficient in terms of cost / benefit ratio, is particularly recommended for plant repowering.

The system is modular, easy to implement even in several steps.

 LOWER IMPACT ON THE ENVIRONMENT

The FLOW: WAVE® disintegration system significantly increases the important environmental advantages that a biogas plant already offers:

  • Drastic reduction of odor and gases produced by animal waste
  • Transformation of waste into renewable energy

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