# Flue Gas Composition and Treatment Potential of a Waste Incineration Plant
## 1 Introduction  
Combustion is defined as a chemical reaction during which the fuel combustible elements are rapidly oxidized and a large quantity of energy is released [1]. The purpose of burning organic fuels in combustion plants is to obtain hot combustion gases which are the primary heating agent in the boiler [2]. The combustion of organic fuels is an exothermic process in which fuel and combustion air are consumed, generating combustion gases and solid products (ash-slag) [1]. Fuels are defined as substances that produce significant amounts of heat by combustion. To be considered as fuel, a substance must meet the following criteria [1]:  
* It should react exothermically with oxygen (air) at high speed and temperature. * The resulting combustion products must be non-toxic (due to the importance of air pollution cleaning systems and CO\({}_{2}\) capture). * It should be widespread in nature. Therefore, it must be cost-effective with no other cheaper alternative uses (this is exactly applied for municipal solid waste (MSW)). * The resulting combustion products should not be corrosive when they come into contact with any exposed surface (this can be achieved by applying a SO\({}_{2}\) reduction system). Solid fuels such as MSW and coal contain varying amounts of carbon, oxygen, hydrogen, nitrogen, sulfur, moisture, and ash, making an exact mass analysis difficult. Combustible mass and ballast are the main fractions in any kind of solid fuel. Combustible mass denotes combustible materials while ballast is the ash-slag. To scale-up the mass of each component (kg component/kg fuel), it is essential to know the elementary chemical composition. Sulfur is an unwanted presence, as it reacts with the moisture in the flue gas, resulting in sulfuric acid, which is extremely corrosive to the metal elements of the combustion plant. As air is free and easy to obtain, it is the main element used for oxidation to burn the fuel and achieve the chemical combustion process. Oxy-fuel combustion technology, where air is replaced by a mixture of pure oxygen and recirculated combustion gases, is one of the most promising techniques for CO\({}_{2}\) capture and CO\({}_{2}\) emission reduction [3]. Depending on the type of combustion (excess air coefficient), the combustion gases may contain:  
* For incomplete combustion (lambda < 1): CO, CO\({}_{2}\), SO\({}_{2}\), H\({}_{2}\)O, and N\({}_{2}\). * For theoretical or stoichiometric combustion (lambda = 1): CO\({}_{2}\), SO\({}_{2}\), H\({}_{2}\)O, and N\({}_{2}\). * For excedentary combustion (lambda > 1): CO\({}_{2}\), SO\({}_{2}\), H\({}_{2}\)O, N\({}_{2}\), and O\({}_{2}\). In general, an inadequate air ratio and poor mixing of air and fuel produces high energy wastage and high pollutant emissions [4; 5]. The cumulative emission of CO\({}_{2}\) affects the climate and is the greatest single contributor to the greenhouse effect [6]. The Kyoto Protocol and the Paris Agreement aim to control greenhouse gas emissions under the United Nations Framework Convention on Climate Change (UNFCCC), in which CO\({}_{2}\) is listed as a major greenhouse gas that needs to be mitigated or recycled [7; 8]. However, waste incineration is much better than landfilling in terms of emissions and the effect on the climate. It should be noted that in many countries, the main method of waste treatment is landfill. In the Middle East and North Africa (MENA) region countries, more than 95% of municipal waste goes to landfill [9; 10; 11]. In our previous work [12], a waste incineration plant was simulated using Epsilon (a specific software package serving as a multi-functional engineering system analysis). Jordan was chosen for the case study, and a 4 kg sample was collected from a 52-ton heap of waste in the waste-converting station in Amman city, which receives waste from six regions, and therefore was considered a representative sample for Jordan. The sample was shredded and prepared for analysis in the laboratory to ascertain its characterization and its element constitution.