Generating small scale power units through biomass gasification

Abstracts

This paper presents research that aims to demonstrate the use of small systems in the generation of power units from forest biomass. This research relies on the development of a biomass gasifies prototype that will form the basic framework for the achievement of this technological ideology. The developed prototype will be farther enhanced by a syngas cleaning system that will achieve engine combustion, which will be used to run the synchronous generator. The safety of the operation of the whole system will be made possible through the development of a monitoring and control system. The monitoring system will ensure that all the subsystems coordinate and achieve the desired results.

Introduction

For a while, now, solid biomass fuels have been the most significant and promising technological advancements that give humanity the hope of reducing fossil fuel consumption in the globe. Clean energy has been considered the best way to tackle rising climatic issues across the world; this includes the issues of global warming and the rise of sea levels. Solid biomass fuel has been entrusted as a huge strategy towards the reduction of greenhouse emissions in Europe according to energy policies established under “The clean energy for all Europeans package.” Following the campaigns initiated globally, the global authorities have committed themselves towards the achievement of neutrality in the carbon emissions in the near future.  The use of biomass to create energy, therefore, is the most desirable option available considering the initiatives towards forest conservation; this makes biomass to be abundant and, therefore, a promising source of energy. The internal combustion engine has made the issue of biomass gasification quite interesting due to the fact that investment in biomass gasification has become quite viable and has attracted the desired economic attention.

According to the literature review presented, there are many factors that guide the choice of the gasification system; some of these factors include gasifier capacity and biomass characterization ( Safarian, 2019). The following segment presents an intensive review of the gasifier integration with the engine to produce renewable electricity for direct consumption.

The gasification system

Biomass gasification entails the combustion of biomass under controlled air supply to yield syngas, which is a mixture of gasses, which are mainly methane, Carbon monoxide, and hydrogen. Quality of the syngas generated in the gasifier solely depends on factors like the flow of air patterns and biomass particles and the entire design of the gasifier. Acceptable quality of syngas can also be achieved mainly through the use of parameters such as the Equivalent Ratio (ER) and the superficial velocity (SV) [2]. The ER can simply be defined as the ration of air volume supplied in the gasifier in relation to the quantity of biomass fuel used. ER is the most delicate and important process in the gasifier since the quality of syngas fully depends on this process. To sum up the gasification system, it can be seen that this section fully depends on the chemical composition of the biomass, such as the particle sizes and the moisture content. The quality of syngas coming out of this system is of great concern since it determines the overall success of the system.

The syngas conditioning

The syngas produced cannot be used in the end applications without being cooled and cleaned properly for the smooth running of the process. A variety of options are present to clean the syngas, some of which are thermal processes, physical processes, and catalytic processes [3]. The most simple way of cleaning the syngas is physical cleaning since it involves filtration or wet scrubbing of the gas in order to remove particulate matter or tar from the gas stream. High or ambient temperatures can be used during filtration; however, scrubbing is restricted to ambient temperatures. In general, the syngas is cleaned following three major stages, which are cyclone separator, cooling towers, and filters.

Biomass conversion to mechanical energy

This segment of the prototype aims to convert the biomass available to mechanical energy that can be father broken down into electric units. The selection of the desired power capacity is the first set in this section since it will offer a guideline to the amount of biomass that will be taken through combustion(Jenkins, 2019). the system to prepare the mixture of gasses in the correct ratio and supply it to the engine will be developed. This fuel supply system consists of a tube where converges, and are mixed, the producer gas coming from the cleaning system and the atmospheric air. The control of the desired composition of the fuel/air mixture is accomplished by metering the admitted air flow rate using a motorized valve. The mixture flow rate supplied to the engine is controlled by a motorized valve located after the mixing zone of the tube. The positions of the valves that provide the required combustible gas mixture load to supply to the engine and the desired air/syngas mixture composition are determined based on the measurement of the air and fuel gas flows. For this purpose, the air and fuel inlet ducts are equipped with air mass

probes.

The electricity generation

This is the most crucial part of the system since it produces the core product, which is electric power. Conversion of mechanical energy to electric energy is done through the use of cost-effective 5 kW synchronous generators. The automatic voltage regulator is one of the characteristics of synchronous generators and hence making the development of the small units of power much easier and efficient through voltage regulation to control the power injected or absorbed from the electric network. This section basically relies on the functionality of the generators; therefore, power frequency control systems are deployed to ensure regulation on systems involving combustion and the general conversion of mechanical energy into electric units(Vera,2018).

Monitoring and control system

This part of the system controls the overall setting in that it ensures that all the parts and the subsystems are working together and provide indications when there is a possible malfunctioning in any of the subsystems. The system provides information about key variables that determine the safety of the whole system and implements high-level management and control functionalities .the basic parameters that are monitored include exit gas temperatures, bed temperatures, biomass consumption rates, gas flow rates, and extraction rates. These parameters measured to provide a picture of the performance of the system and can help in decision making in case there is a possibility of brake down being detected. The monitoring system also entails ventilation, which enables the injection of gases and any other valuables needed to keep the whole system.

The following is the overview of the small scale power gasification plant in its complete form:

Conclusion

Through technology, the world has the potential to achieve the desired amounts of clean energy, as seen in the prototype above. Through the usage of biomass and technological advancements that reduce the amounts of carbon emission, the world can realize its goals in countering climate change.

References

Jenkins, B. M., Baxter, L. L., & Koppejan, J. (2019). Biomass combustion. Thermochemical processing of biomass: conversion into fuels, chemicals, and power, 49-83.

Safarian, S., Unnþórsson, R., & Richter, C. (2019). A review of biomass gasification modeling.    Renewable and Sustainable Energy Reviews, 110, 378-391.

Vera, D., Jurado, F., Carpio, J., & Kamel, S. (2018). Biomass gasification coupled to an EFGT-ORC        combined system to maximize the electrical energy generation: A case applied to the olive oil         industry.           Energy, 144, 41-53.