With the number of industries growing around the world, more energy is needed. As fossil fuels are decreasing, there is a need to look for other alternatives as well as to improve the usage of the present stock. In line with the large amount of coal available, people are looking at producing cleaner source of energy by using them. Therefore, hydro gasification is a process that is able to produce substitute natural gas (SNG), containing mostly methane, from the reaction between coals and hydrogen under high pressures. The main drawback for this process is that it is the slowness and the amount of methane produce is not justifiable by the cost incurred in producing it when compared to mining of the n.1tu.ral gas. Therefore, this thesis studies the effects of pressure in coal hydrogasification.
The studying of the effects of pressure in coal hydro gasification will be done by reviewing journal papers by previous researches, followed by a comparison of all their results as the experiment pressures for in the range of between 0- 8 MPa. Before the studying of effects pressure in coal hydrogasification, one must first obtain information regarding hydro gasification and the studying of different information that co-relates with the pressure effects in coal hydrogasification. This is necessary for providing a logical and well-supported explanation regarding the different results from the various experiments from the journals.
According to the results from various researchers, most coals obtained at least 50% of conversion frou1 coal-hydrogen reaction to methane; with the increase of pressure, the percentage of methane yield increases. Further verification using the mechanism model of hydrogasification by Wen et al. corresponds with the results from the various experiment that the influence of pressure increases the methane yield.
One possible explanation to the difference in percentage yield of methane concerns the structure of the aromatics in the coal because coals with a stronger naphthalene structure resulted in a higher percentage yield. The difference in coal particle size also is a factor because the larger the particle size the greater the pressure is needed.
These are some causes that affect the pressure in coal hydrogasification. Additional experiments can be done to fully understand the effects of pressure on coal hydrogasification. In conjunction with the study of the results from the experiments, this can lead to an increase in methane production and the reduction of time spent during hydrogasification process - the two main drawbacks in this process.