As a part of technology development for waste processing / recycling work, we at Vigyan ashram are working on development of technology for easy & safe disposal of sanitory pads & other medical waste.
In this work , a recent development is new model of sanitory pad recycler based on pyrolysis prociple.
New model is developed that uses pyrolysis to decompose sanitary napkins into hydrocarbon vapours and combustible gases along with some non-combustible gases and char. These vapours and gases are made to pass over high temperature electric coils (>500 degC) where they auto ignite in the presence of oxygen. The heat from the flames partially drives the pyrolysis of remaining sanitary pads. A smoke stack thermocouple sensor feeds back values to a PID controller implemented through a microcontroller to maintain proper pyrolysis and combustion conditions that result in a transparent flue gases exiting from the chimney.
This model / technic deferens in process of incineration than present available solution in market with following aspects –
- A drying stage is implemented where the temperatures are kept near 120-200 deg C in the chamber containing the sanitary napkins. This step reduces energy consumption for incineration.
- A separate process of pyrolysis is used where the chamber containing sanitary napkins is heated to above 300 degC. This process generates a steady stream of combustible pyrolysis vapours and gases. Due to Pyrolysis smoke emission is very less can compare to earlier models.
- These gases further pass over the red hot electric coil where they flame and incinerate inside material.
These process are combined into a compact thermally insulated product which is controlled by a microcontroller system.
To achieve the desired low emission & energy use for incineration the following processes are required:
- Using an electric coil generate high temperatures, around 500 degC.
- Use the high temperatures to cause pyrolysis (begins above 300 deg C) of sanitary pad material and bodily wastes, decomposing them into hydrocarbon vapours and combustible gases (CO).
- Ensure that HC and combustible gaseous fumes mix with sufficient air to produce lean or at the most stoichiometric ratio mixture.
- Ensure that the gas mixture passes through the high temperature electric coils to result in autoignition and flaming reactions.
- Harvest the exothermic heat from the combustion of pyrolysis gases to lessen the role of electric coil in the pyrolysis process.
- Exit the combustion gases through a simple chimney.
- Use a microcontroller to implement a PID controller for electric heater using flue gas temperatures as feedback.
Presently we are conduction field trial for this model & hopeful will be ready with marketable model in next 3-4 months.
FOr any further details please write us on vapabal@gmail.com
