ADNEX PILOT PLANT
ADNEX consists of a process for the extraction of nitrogen that is contained in an ammonia form, in digestates that derive from the methanogenic fermentation of manure and sewage sludge and for its energy use.
The experimentation for the application of this new technology has required several months of practice which is still on going.
We are in fact with this project applying knowledge that has already been established (stripping of ammonia) and then adapting it to a new technology for the treatment of organic matrix.
This experimentation has been conducted using a purpose-built prototype.
The above mentioned prototype in fact simulates what actually happens in a plant for treatment of biological materials on a real scale that has allowed us to define all the parameters (temperature, pH, time, volume) needed to ensure the most efficient extraction of ammonia.
The prototype is composed of a rather complex reactor, which thanks to its probes and sensors necessary for measuring and regulating temperature, pH and flow rate of the gas bubbling, has allowed us to test different combinations of the parameters that we are interested in.
The real innovation, and the subject of our continuous tests, is the ammonia treatment after extraction.
The alternatives considered are two:
The criteria adopted for the analysis and evaluation of treatments are energy recovery and the production of pollutants, specifically of NOx.
The first hypothesis, combustion foresees that the extracted ammonia is injected directly into the flame with the main fuel (CNG and LPG) which then actually becomes a fuel itself. The energy recovery can be quantified by the calories produced by the combustion of ammonia, namely, equal to thermal energy produced, by the reduction of the consumption of methane or glp.
The cracking allows, at high temperatures, to dissociate the ammonia into diatomic nitrogen and hydrogen. Diatomic nitrogen may be released into the atmosphere while hydrogen can become a fuel.
For this reason, we have evaluated the possibility of combining the two treatments, channeling gas out of the cracking into the burner.
The process requires, however a large energy expenditure to bring the gas to a cracking temperature.
In addition, the diatomic nitrogen needs to be conveyed to the flame with hydrogen which is split, contributing to the formation of NOX.
The last component of the prototype consists of three bubbling towers in series. The bubblers allow us to trap the exhaust gases of combustion in an absorption solution for NOX, in such a way that they can be quantified.
The quantification of NOX is crucial to implement the evaluation process.
To be able to perfect the technology and to adapt it better to the different needs requires further experimentation.