Biogas Digester Types And Operational Parameters

Description

ABSTRACT

The biogas production technology has improved over the last years for the aim of reducing the costs of the process, increasing the biogas yields, and minimizing the greenhouse gas emissions. To obtain a stable and efficient biogas production, there are several design considerations and operational parameters to be taken into account. Besides, adapting the process to unanticipated conditions can be achieved by adequate monitoring of various operational parameters. Choosing a right biogas digester is a very important while constructing a biogas plant. From the standpoint of fluid dynamics and structural strength, an egg-shaped vessel is about the best possible solution. This type of construction, however, is comparatively expensive, therefore, its use is usually restricted to large-scale sewage treatment plants.  This paper discusses different types of biogas plant. This review paper summarizes the developments in biogas design and operation, while highlighting the main factors that affect the efficiency of the anaerobic digestion process. The study’s outcomes revealed that the optimum operational values of the main parameters may vary from one biogas plant to another. Additionally, the negative conditions that should be avoided while operating a biogas plant were identified.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE PROJECT
• AIM AND OBJECTIVE OF THE PROJECT
• SCOPE OF THE PROJECT
• PURPOSE OF THE STUDY
• LIMITATION OF THE STUDY
• METHODOLOGY
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

• OVERVIEW OF BIOGAS
• DESCRIPTION OF DIGESTER
• TYPES OF SMALL-SCALE DIGESTERS

CHAPTER THREE

METHODOLOGY

• REACTOR DESIGN CONSIDERATIONS AND OPERATIONAL CONDITIONS

CHAPTER FOUR

4.0        THE CONDITIONS INSIDE THE REACTOR

• MONITORING OF THE OPERATIONAL CONDITIONS IN BIOGAS PLANTS

CHAPTER FIVE

• CONCLUSION
• REFERENCES

CHAPTER ONE

1.0                                                                  INTRODUCTION

1.1                                                     BACKGROUND OF THE STUDY

To meet the increased demand for energy needs and to reduce greenhouse gas emissions, the capacity of worldwide installed renewable energy systems has been doubled over the last decade [Hren, R.; Petrovicˇ, A.; Cˇ ucˇek, L.; Simonicˇ, M, 2010]. This also applies to biogas as a source of renewable energy, where the number of biogas plants installed in Europe has been increased from 6227 in 2009 to reach 18,202 by the end of 2018 [Piwowar, 2010]. The total produced electricity from biogas reached 88 TWh in 2017, 40% of which was generated in Germany [Refai, 2016]. Hence, Germany is a leading country in this field [Piwowar, 2020]. Biogas can be utilized—after treatment—in numerous applications, like electricity and heat generation, connection to the natural gas grid, or as biofuel in vehicles [Rosén, 2019].

Anaerobic digestion is a biological process, in which the microorganisms degrade the complex organic matter to simpler components under anaerobic conditions to produce biogas and fertilizer. This process has many environmental benefits, such as green energy production, organic waste treatment, environmental protection, and greenhouse gas emissions reduction [Rosén, 2019]. The biodegradation of the complex organic matter undergoes four main steps. Namely, hydrolysis, acidogenesis, acetogenesis, and methanogenesis.

Biogas consists mainly of CH₄ and CO₂—the share of CH₄ is determined by the type of the feedstock fed into the biogas plant [Falk, 2011]. The different operational conditions also have significant effects on the biogas production potentials. In order to obtain the optimum biogas production with the lowest costs, the biogas plant design has to be optimized as per the needs and potentials. The design criteria of biogas plants (explained in the following section) should be considered for their construction [Rohstoffe, 2012]. Additionally, several parameters have to be controlled to prevent problems causing inhibition in biogas plants (Figure 1). Temperature, pH value, retention time, and organic loading rate have a direct effect on the microbial activity. Moreover, the physical features of the feedstock can vary, and it may contain toxic substances which can influence the microbial activities [Refai, 2016].

Figure 1. Operational parameters of the biogas plant.

1.2                             AIM OF THE STUDY

The aim is to assess the different parameters affecting the biogas production for an optimized biogas plant design and operational conditions. The objectives are:

1. To understand the construction requirement for different types of biogas digester
2. To costs of the process

• To increase the biogas yields

1.3                                                         SCOPE OF THE STUDY

In this work, different types of biogas digester types were discussed and a description of the anaerobic process that takes place in biogas plants is presented. Also, the operational conditions and the available technologies—including their advantages and disadvantages—are thoroughly discussed.   Specifically, parameters defining the reactor’s design, the operational conditions, and the monitoring procedures are summarized and discussed.

        1.4                                                  PURPOSE OF THE STUDY

The main purpose of this study is to become familiar with different types of biogas digester and digester operating parameter thereby reducing the costs of the process, increasing the biogas yields.

1.5                                                   RESEARCH METHODOLOGY

The study was conducted by means of a literature review on articles, books, regulation agencies, and internet documents.

1.6                                                   LIMITATION OF THE STUDY

As we all know that no human effort to achieve a set of goals goes without difficulties, certain constraints were encountered in the course of carrying out this project and they are as follows:-

1. Difficulty in information collection: I found it too difficult in laying hands of useful information regarding this work and this course me to visit different libraries and internet for solution.
2. Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).

• Time Constraint: The researcher will simultaneously engage in this study with other academic work. This consequently will cut down on the time devoted for the research work.