**2.3 Syngas composition and its calorific value**

The composition of the manufacturer's gas depends on feedstock, particulate size, gas flow rate and feedstock flow, chemical reactor configurations, operating

**25**

*Syngas Production, Properties, and Its Importance DOI: http://dx.doi.org/10.5772/intechopen.89379*

exceed 6 MJ/Nm3

and flashing.

based crude oil.

**3.2 Gasification**

.

**3. Production of synthesis gas**

(H2O) may also be present in syngas.

**reforming of natural gas**

needs the ratio from H2 to CO. H2:CO Both.

reaction can be summarized by Eqs. (1) and (2).

conditions or process of gasification, gasificator and catalyst, and gas residence time. But the temperature of the reactor, which in turn is affected by the ER value, mainly influences it. Furthermore, CO, H2, and CH4 concentrations in producer gas

There is, therefore, a considerable influence on the calorific value of the producer gas on the type of oxidizing agent used for gasification. As ER increases and then the concentrations of these useful components decreases because of the intensification of combustion at higher ER values, the concentrations of CO and H2 reach the maximum value. As ER increases, the concentrations of CO2 and N2 in the producer gas are also increased [4]. Air as an oxidant produces syngas with relatively high levels of nitrogen and thus a lower heat value, which does not normally

The producer's gas is classified as fuel gas of low quality. The typical biomass gasification composition of an air-borne downdraft reactor with the oxidizer is as follows: 15–20% of H2, 15–20% of CO, 0.5–2% of CH4, 10–15% of CO2, and the rest of the component of N2, O2, and CXHY. If the concentration of fuel components is considerately increased and the gas is called a medium heat value, up to 16 MJ/Nm3

Synthesis gas or syngas is called carbon monoxide (CO)-hydrogen (H2) containing gas mixture. Carbon dioxide (CO2) and other components such as water

**3.1 Production of fuels and chemicals from gasification of biomass/coal or** 

drying is integrated into a gasifier reactor vessel by certain gasifiers [7].

The feedstock must be gasified when beginning with a solid feedstock, such as biomass or coal. It may be necessary to ground or pulverize the feedstock before gasification (usually carbon). The particle fineness depends on the gasification type. For most biomass gasification plants, drying is required as the next step. The

Following gasification, the product is a gas, known as producer gas, filled with impurities that must be removed. Prior to synthesis, the producer of gas usually also

All hydrocarbon feed resources like coal, heavy oils, or combustible biomass can be gasified as synthesis gas. Several reactions occur in the gasificator, but the total

Biomass + O2 → CO + H2 + CO2 + H2O + CH4 (1)

The chemical synthesis can be used as a building block in all products normally produced from crude oil or natural gas. Petrol and diesel are fuels with definitions, which are not based on the chemistry but on their physical qualities such as boiling

The octane rating of gasoline in an internal combustion (IC) engine is empirical and based on its actual performance. This means that at least low-grade blending is possible as long as synthetic fuel matches the characteristics of petrol- or diesel-

are also controlled by chemical reactions in the process of gasification.

[6], where oxygen or water steam or the mixture of both are used.

*Syngas Production, Properties, and Its Importance DOI: http://dx.doi.org/10.5772/intechopen.89379*

*Sustainable Alternative Syngas Fuel*

**2. Major properties of syngas**

*Present world syngas market, totally ~6 EJ/y.*

**Figure 1.**

**2.1 Syngas flammability limits**

**2.2 Laminar flame velocity**

combustion chamber and its emission performance.

equivalence ratio, temperature, and pressure affects it.

**2.3 Syngas composition and its calorific value**

Different characteristics of syngas can affect the process of combustion in internal combustion (IC) motors. The flammability limit of the syngas is one of the most important properties in IC engine safety and fuel. Also, the laminar flame velocity [3] (burning velocity) is an essential parameter to investigate the operation of the

The limit of flammability is usually used as an index for the flammability of the gas. This describes the range of the fuel concentrations in the fuel/air mixture at certain temperature and pressure, which allow the ignition of the flame to propagate and sustain the flammability limits [4] are known in line with generally accepted usages as those fuel-air areas where flame propagation can take place and where fire cannot propagate. The fuel, the spread direction, the size and the form of the combustion chamber, the temperature, and the pressure are primarily affected [4]. And for the fuel-air blend, there are two distinct flammability limits, namely the smallest fuel boundary the flames can propagate is called the lower flammability boundary (LFL), while the richest one is called the upper flammability boundary (UFL). The fact that H2 and CO are the principal flame-retardant components of syngas inherits the characteristics of these gasses. The presence of inert gasses such as nitrogen and carbon dioxide in the gas mixtures reduces the flammability limit.

The laminar flash speed is the speed at which the flame propagates in the direction of expansion wave surfaces under a laminar flow condition via quiet unbranded fuel-oxidant mixes [5]. Because LFV is highly sensitive to combustion chamber operations and emission performance, it is very important for the investigation of combustion chamber operations. The composition of the fuel, mixture

The composition of the manufacturer's gas depends on feedstock, particulate size, gas flow rate and feedstock flow, chemical reactor configurations, operating

**24**

conditions or process of gasification, gasificator and catalyst, and gas residence time. But the temperature of the reactor, which in turn is affected by the ER value, mainly influences it. Furthermore, CO, H2, and CH4 concentrations in producer gas are also controlled by chemical reactions in the process of gasification.

There is, therefore, a considerable influence on the calorific value of the producer gas on the type of oxidizing agent used for gasification. As ER increases and then the concentrations of these useful components decreases because of the intensification of combustion at higher ER values, the concentrations of CO and H2 reach the maximum value. As ER increases, the concentrations of CO2 and N2 in the producer gas are also increased [4]. Air as an oxidant produces syngas with relatively high levels of nitrogen and thus a lower heat value, which does not normally exceed 6 MJ/Nm3 .

The producer's gas is classified as fuel gas of low quality. The typical biomass gasification composition of an air-borne downdraft reactor with the oxidizer is as follows: 15–20% of H2, 15–20% of CO, 0.5–2% of CH4, 10–15% of CO2, and the rest of the component of N2, O2, and CXHY. If the concentration of fuel components is considerately increased and the gas is called a medium heat value, up to 16 MJ/Nm3 [6], where oxygen or water steam or the mixture of both are used.

## **3. Production of synthesis gas**

Synthesis gas or syngas is called carbon monoxide (CO)-hydrogen (H2) containing gas mixture. Carbon dioxide (CO2) and other components such as water (H2O) may also be present in syngas.

The chemical synthesis can be used as a building block in all products normally produced from crude oil or natural gas. Petrol and diesel are fuels with definitions, which are not based on the chemistry but on their physical qualities such as boiling and flashing.

The octane rating of gasoline in an internal combustion (IC) engine is empirical and based on its actual performance. This means that at least low-grade blending is possible as long as synthetic fuel matches the characteristics of petrol- or dieselbased crude oil.

## **3.1 Production of fuels and chemicals from gasification of biomass/coal or reforming of natural gas**

The feedstock must be gasified when beginning with a solid feedstock, such as biomass or coal. It may be necessary to ground or pulverize the feedstock before gasification (usually carbon). The particle fineness depends on the gasification type. For most biomass gasification plants, drying is required as the next step. The drying is integrated into a gasifier reactor vessel by certain gasifiers [7].

Following gasification, the product is a gas, known as producer gas, filled with impurities that must be removed. Prior to synthesis, the producer of gas usually also needs the ratio from H2 to CO. H2:CO Both.

#### **3.2 Gasification**

All hydrocarbon feed resources like coal, heavy oils, or combustible biomass can be gasified as synthesis gas. Several reactions occur in the gasificator, but the total reaction can be summarized by Eqs. (1) and (2).

$$\text{Biomass} + \text{O}\_2 \rightarrow \text{CO} + \text{H}\_2 + \text{CO}\_2 + \text{H}\_2\text{O} + \text{CH}\_4\tag{1}$$


**Table 1.**

*Composition of producer gas [8].*

By-products: tar, char, ashes. Reaction conditions:


The reaction also can be expressed as:

$$\text{CaHbOcNd} + \text{O}\_2/\text{H}\_2\text{O/N}\_2 \rightarrow \text{CO} + \text{H}\_2 + \text{CrHyOz} + \text{CO}\_2 + \text{H}\_2\text{O} + \text{NH}\_3 + \text{N}\_2 \quad \text{(2)}$$

The solid carbon is partially oxidized with oxygen (O2), air, steam (H2O), or a combination of all gasification agents. CxHyOz is mostly made of methane with a few low percent of hydrocarbon, including ethane and ethylene (**Table 1**). For most gasifiers, gas may also contain heavier hydrocarbons such as benzene, toluene, and naphthalenes, depending on the feedstock and the operational parameters. Hydrocarbons, which are heavier than benzene, are often known as tars (**Figure 2**).

This is an important factor in determining the technical mechanism and the economic feasibility of the gasification system. Efficiencies in gasification are based on the biomass type used, its particle size, its ER value, and the reactor design [8].

The gasification efficiency is usually determined on the lower heating value basis. The efficiency is calculated as the ratio of the total energy in the producer gas (sensible and chemical) and the chemical energy in the feedstock (the heating value). Depending on type and design of the gasifier as well as on the characteristics of the fuel, mechanical gasifier efficiency may vary between 60 and 75%. A useful definition of the gasification efficiency (%) used for engine applications is as follows: ηm = \_

$$
\eta\_{\rm m} = \frac{\rm{H\_{\rm g}} \times \rm{Q\_{\rm g}}}{\rm{H\_{\rm s}} \times \rm{M\_{\rm s}}} \times 100
$$

where ηm is the gasification efficiency (%) (mechanical), Hg is the heating value of the gas (kJ/m3 ), Qg is the volume flow of gas (m3 /s), Hs is the lower heating value of gasifier fuel (kJ/kg), and Ms is the gasifier solid fuel consumption (kg/s).
