Greeting,
I'm studying some gasification.
In one paper, I found the lower heating value (LHV) which can be expressed by LHV = 10.78H2(%) + 12.63CO(%) + 35.88CH4 (%) + 56.5C2H2 (%) + 64.5C2H6 (%) for gasification of glycerol.
Here, I have some questions.
1. What do the numbers (10.78, 12.63, 35.88, 56.5, 64.5) mean? How can be they calculated?..
2. There are two heating values (HHV and LHV). Then, what is the advantage and purpose of using LHV than HHV?..
Can you give me the help and discussion?
Thank you so much!
Ref: Tamošiūnas, Andrius, et al. "Thermal arc plasma gasification of waste glycerol to syngas." Applied Energy 251 (2019): 113306.
The numbers are the LHV of each gas component expressed as MJ/Nm3. That is, H2 has a LHV of 10.78 MJ/Nm3, CO has a LHV of 12.63 MJ/Nm3 and so on.
H2(%), CO(%)... are the content of gaseous products in the producer gas (vol.%).
The difference between the LHV and the HHV is the heat of vaporization of the water. In systems where you can't take advantage of the heat of vaporization of the water, it makes sense to use the LHV.
The correlation is build up of the composition of the sun gas. The syn gas is mainly mix of H2 and CO. The ratio of these main constituents will depend on the nature of the Hydrocarbon fed to the Gasification POX reactor. coal more carbon tens fuel will yield more CO and less H2. Type of gasification (dry or quench type) will have different H2/CO ration due to CO shift reaction. C1 make is measured in the Syn gas to control the O2 addition in the POX to minimize C1 and C2 make.
LHV is used for calculating the energy That can be extracted from using Syn Gas.
usually for power generation N2 is added to the syn gas going to gas turbines which leads to reducing the Heating value of the gas turbine fired diluted syn gas.
thus required more flow of fuel for the same heat rate input in the gas turbine and higher power output compared on using methane with the same heat rate.
I agree with Jörgen. A few other details. 1) There are similar formulas for HHV, but you might note that they contain a term for H2O(g) as well. The LHV is a measure of the heat release from combusting fuel when its products contain only water vapor. If the H2O in the initial fuel is vapor, it will have no contribution to the LHV. However, if it is a wet syngas with liquid water in it, the H2O makes a large and negative contribution to the LHV. 2) Similarly, the HHV will have a positive term for water vapor and no term for liquid water for similar reasons. 3) If the syngas contains tar or other hydrocarbons in either the gas or liquid phases, which are common, there are additional large and positive contributions for both LHV and HHV.
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