Integrated Waste-to-Energy Process for High Thermoelectric Yields
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Solution Overview
Problem
Current waste management technologies face limitations in maximizing thermoelectric yields due to the presence of chlorine and chlorides, which reduce electrical energy production, and require significant investments for incineration and infrastructure, while also posing environmental concerns.
Innovation Solution
An integrated process that transforms municipal solid waste into Refuse-Derived Fuel (RDF) through bio-drying and anaerobic digestion in bioreactors, producing purified biogas to enhance steam heat content and reduce combustor load, allowing for higher energy recovery without the need for a separate thermoelectric plant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If waste is combusted directly in incinerators, then electrical energy can be produced, but the presence of chlorine and chlorides limits combustion yields and requires operation at low steam temperatures (around 400°C), resulting in low electrical energy yields (around 25%)
Solution Approach 1:
The patent applies preliminary action by performing aerobic digestion and bio-drying of waste before combustion. This pre-treatment removes moisture and stabilizes the waste, transforming it into RDF with improved combustion characteristics. The putrescible material is digested aerobically to evaporate water and produce a fuel with high heating value, which then can be combusted more efficiently without the same limitations as raw waste.
Solution Approach 2:
The patent changes physical and chemical parameters of the waste through bio-drying and aerobic digestion. The moisture content is reduced from typical waste levels (around 50-60%) to lower levels suitable for efficient combustion. The heating value is increased through removal of non-combustible materials and concentration of combustible components, enabling higher combustion temperatures and improved electrical energy yields.
2Loss of energy
If large waste combustors are combined with conventional thermoelectric plants to improve yields to around 32%, then electrical energy production increases, but significant investments are required for both combustor and power plant infrastructure
Solution Approach 1:
The patent applies multi-functionality by designing the waste treatment system to serve multiple purposes: aerobic digestion produces both a stabilized fuel (RDF) and energy through biogas production. The bioreactor system simultaneously treats waste, produces energy, and prepares material for combustion, eliminating the need for separate thermoelectric plant infrastructure while maintaining high energy yields.
Solution Approach 2:
The system applies self-service through internal energy generation via biogas production from the bioreactor. The biogas produced during anaerobic digestion is used to supplement combustion in the combustor, providing self-sufficient energy enhancement without requiring external power plant infrastructure. This allows the system to improve electrical energy yields while avoiding the complex integration and high investments of conventional thermoelectric plants.
3Productivity
If RDF is dumped in non-conventional landfills and activated for biogas production, then very high productivity levels are achieved, but the system requires careful management of water addition and biogas collection infrastructure
Solution Approach 1:
The patent applies continuity by implementing a continuous aerobic digestion process in the bioreactor system. Water is added continuously to maintain optimal moisture levels for microbial activity, and biogas is collected continuously rather than in batch operations. This continuous operation maintains high productivity levels while simplifying management compared to intermittent activation processes.
Solution Approach 2:
The patent uses an intermediary approach by introducing controlled amounts of water as a mediator to activate and sustain the biological processes. The water addition is carefully managed to provide necessary moisture for microbial activity without creating excess liquid that would complicate biogas collection. The system also uses intermediate storage and processing steps to buffer between waste input and biogas output, easing operational management.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly increases thermoelectric yields, reduces investment costs, and minimizes environmental impact by producing high-energy-content RDF and purified biogas, enabling efficient energy recovery and safer waste storage.
Implementation Method 1
anaerobic digestion in bioreactors, producing purified biogas
Implementation Method 2
aerobic digestion of the putrescible material with low heating value to evaporate the water and obtain a fuel with a high heating value
Implementation Method 3
combustion of the waste and also of RDF has technological limitations concerning the combustion yields
Data Source
AI summary
A process is described for obtaining energy from waste, comprising the following phases: a) bio-drying of municipal solid waste (MSW) to transform it into refuse-derived fuel (RDF), a dry, homogeneous material with piece size of around 20-30 cm, known by the name of RDF; b) compacting of the material obtained from phase a) into bales or BIOCUBI® and storage of the BIOCUBI® in bioreactors; c) activation by wetting with water of the bioreactors to produce biogas by anaerobic digestion; d) combustion at the start of the material obtained from phase a) (RDF) and subsequently of the residue already digested in the bioreactors, and therefore not biodegradable, in a waste combustor provided with a system of purification of combustion gasses and production of superheated steam at approximately 400°C and pressure of around 70 bar; e) combustion of the purified biogas in a conventional boiler provided with re-superheaters for raising the temperature of the steam produced by the waste combustor by approximately 100°C; f) use of the steam produced in this way in a turbine coupled with an alternator for the production of electrical energy. The invention also relates to a system for the implementation of this method.