Biomass Pellet Drying and Combustion Plant
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Solution Overview
Problem
Current biomass cogeneration plants are costly and complex, especially when handling smaller quantities of biomass, and lack efficient means to transform thermal energy into electricity, making them unsustainable for individual farmers and inefficient in energy conversion.
Innovation Solution
A plant design that utilizes biomass pellets with a simplified structure and process, incorporating a pellet-making system to standardize biomass into uniform pellets with low humidity, which are then fed into a pyrolysis system with oxygen in excess, allowing for efficient thermal energy conversion and optional electricity production through microgeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional cogeneration plants are used for biomass combustion, then thermal energy and electricity can be produced, but the plants are costly and complex especially for smaller quantities of biomass
Solution Approach 1:
The plant is divided into distinct functional modules: a drying chamber (14) with helical mixing-feeding means, a combustion chamber (70) with cascading braziers, and a heat recovery system. This modular segmentation allows each component to be optimized independently and simplifies the overall system structure, making it suitable for smaller-scale applications while maintaining production efficiency.
Solution Approach 2:
The drying chamber performs preliminary drying of biomass pellets using combustion fumes before they enter the combustion chamber. The helical mixing-feeding means pre-mixes and feeds the pellets systematically. This preliminary action ensures optimal combustion conditions are met before the main energy conversion process, improving overall efficiency while simplifying the combustion chamber design.
2Use of energy by moving object
If direct combustion of biomass is performed, then thermal energy is produced, but dust and ash emissions are generated requiring complex treatment equipment
Solution Approach 1:
The plant converts the harmful combustion fumes (which would be emissions) into a useful resource by using them to dry the biomass pellets in the drying chamber. The fumes that would otherwise be wasted or require treatment are instead utilized for the drying process, reducing the volume and temperature of exhaust gases and thereby reducing dust and ash emissions.
Solution Approach 2:
The system recovers thermal energy from the combustion fumes by channeling them through the drying chamber to dry incoming pellets. This recovery process extracts useful energy from what would be waste heat, improving overall energy efficiency and reducing the thermal load on emission treatment systems.
3Productivity
If biomass is not standardized into pellets, then handling is simpler, but combustion efficiency and energy conversion are reduced
Solution Approach 1:
The biomass is transformed into pellets with standardized physical parameters (size, shape, density, and humidity content). This parameter standardization ensures consistent combustion characteristics and optimal feeding into the combustion chamber. The drying chamber further controls the humidity parameter by using combustion fumes to dry the pellets to the desired moisture content before combustion.
4Productivity
If equipment is designed for large-size plants, then processing capacity is high, but cost and complexity cannot be sustained by individual farmers
Solution Approach 1:
The drying chamber operates using its own combustion fumes as the drying medium, eliminating the need for external energy sources or complex drying equipment. The helical mixing-feeding means automatically feeds the pellets through the drying and combustion processes. This self-service approach reduces operational complexity and costs while maintaining effective processing capacity suitable for individual farms.
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
The plant is simpler and less costly to construct and operate, enabling efficient production of thermal energy and electricity from biomass pellets, particularly suitable for smaller-scale applications, with reduced ash and dust emissions and compliance with environmental regulations.
Implementation Method 1
said drying chamber comprising on its inner surface coaxial helical means fixed for mixing-feeding the pellets
Implementation Method 2
a combustion chamber into which the biomass chopped by the pulveriser means falls and in which combustion of the same takes place
Implementation Method 3
a heat exchanger which uses part of the heat produced in the combustion chamber to heat up to at least 450°C an airflow
Implementation Method 4
pyrolysis with oxygen in excess, and can be sized also to treat reduced quantities of biomass
Implementation Method 5
thermo-chemical process of combustion also produces ash and dust
Data Source
Figure 1
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AI summary
The plant (10) allows the production of thermal energy from biomass supplied in the form of pellets with humidity no higher than 35%, and comprises: a drying chamber (14) for the pellets; a combustion chamber (70) provided with at least two braziers (72, 74) one above the other, adapted to collect the pellets in cascade, and also with means (76) for vibrating the braziers (72, 74) so that the ashes drop into a collecting compartment (90); means for collecting part of the fumes produced in the combustion chamber (70) and conveying them into the drying chamber (14); a heat exchanger (98) for recovering thermal energy from the fumes en route to the chimney. The drying chamber (14) has a cylindrical casing (16) with horizontal axis, the casing (16) being motorised to rotate about its own axis. Coaxial helical means (18) are fixed to its inner wall for mixing- feeding the pellets. A metering device (60) is also provided for feeding the combustion chamber (70) with the dried pellets. In the upper part of the combustion chamber (70) means (68) are provided for retaining the pellets for a time sufficient to cause the formation of syngas, and means (78) for collecting the syngas formed. The plant (10) also comprises means (85, 86) for collecting the fumes and the exhalations present in the drying chamber (14) and conveying them to a mixer (88) where they are mixed with an appropriate quantity of air, and also means (91) for feeding the mixture obtained in the mixer (88) to the combustion chamber (70) in the area of the braziers (72, 74) so that the process of pyrolysis with oxygen in excess takes place, and means (80) for feeding the syngas to the combustion chamber (70). The plant can be completed with conventional equipment (108, 110, 112) which allows the thermal energy produced to be transformed wholly or partly into electricity.