1The hydrogen to carbon (H/C) ratio of coal gasified gas ranges of 0.2-1.0, far 2 less than the desired value for the coal to methanol process. Therefore, a water gas 3 shift unit is needed to raise the H/C ratio, which results in a great deal of CO 2 4 emission and carbon resource waste. At the same time, there is 7×10 10 m 3 coke-oven 5 gas (COG) produced in coke plants annually in China. The hydrogen-rich COG 6 consists of 60% hydrogen and 26% methane. However, massive of COG is utilized as 7 fuel or discharged directly into the air, which makes a waste of precious hydrogen 8 resource and causes serious environmental pollution. This paper proposes an 9 integrated process of coke-oven gas and coal gasification to methanol, in which a 10 tri-reforming reaction is used to convert methane and CO 2 to syngas. The carbon 11 utilization and energy efficiency of the new process increase about 25% and 10%, 12 while CO 2 emission declines by 44% in comparison to the conventional coal to 13 methanol process. 14 15
The increasing demand
of crude oil is in conflict with the shortage
of supply, forcing many countries to seek for alternative energy resources.
Oil shale is welcomed by many countries that are short of conventional
fossil fuels. China mainly uses retorting technology for shale oil
production. Fushun-type oil shale retorting technology takes the largest
share in the oil shale industry. However, this technology is always
criticized by its unsatisfactory economic performance. It is caused
by many reasons. One of the most important problems is the inefficient
utilization of retorting gas. The idea of our research is to utilize
the retorting gas to produce higher valued chemicals. For this, chemical
looping technology is integrated into the retorting process for hydrogen
production. This proposed process is modeled and simulated to build
its mass and energy balance. Techno-economic analysis is conducted
and compared to the analysis of the Fushun-type oil shale retorting
process. The results show that the exergy destruction of the proposed
process is 235.62 MW, much lower than that of the conventional process,
274.76 MW. In addition, the proposed process is less dependent on
shale oil price. Two shale oil price scenarios have been investigated,
showing that the proposed process can still be of benefit, 10.62%
ROI, at low shale oil price, while the ROI of the conventional process
is −2.07%.
The screening of
high-efficiency and low-energy consumption absorbents
is critical for capturing SO2. In this study, absorbents
with better performance are screened based on mechanism, model, calculation,
verification, and analysis methods. The acidity coefficient (pK
a) values of ethylenediamine (EDA), piperazine
(PZ), 1-(2-hydroxyethyl)piperazine (HEP), 1,4-bis(2-hydroxyethyl)piperazine
(DIHEP), and 1-(2-hydroxyethyl)-4-(2-hydroxypropyl)piperazine (HEHPP)
are calculated by quantum chemical methods. A mathematical model of
the SO2 cyclic absorption capacity per amine (αc) in the amine-based SO2 capture process is built
based on the electroneutrality of the solution. Another model of desorption
reaction heat (Q
des) is also built based
on the van’t Hoff equation. Correspondingly, αc and Q
des of the above five diamines
are calculated and verified with the experimental data. The results
show that αc of the diamine changes with the increase
in the pK
a value, and the increase in
the pK
a value directly leads to changes
in Q
des. The order of αc of the above five diamines is EDA > PZ > HEHPP > HEP >
DIHEP, and
the order of Q
des is EDA > PZ >
HEHPP
> DIHEP > HEP. The multiobjective analysis between αc and Q
des suggests that it is
not advisable
to simply pursue a higher αc while ignoring Q
des. The compound quaternary system absorbent
has a wider range of αc than the single ternary absorbent,
which is the direction of absorbent development. This study is expected
to strengthen absorbent screening for the amine-based SO2 capture process from flue gas.
Shale oil is regarded
as an alternative to crude oil, and the use
of this resource can relieve the crude oil supply shortage. China
has abundant oil shale resources, and the conventional shale oil production
process is based on oil shale pyrolysis (OSP). However, oil shale
pyrolysis suffers from unsatisfactory technoeconomic performance.
The process has many constraints, among which the most important constraint
is the inefficient utilization of oil shale pyrolysis gas. The driving
force determining the energy-efficient and economically beneficial
use of pyrolysis gas calls for chemical conversion for high-value
chemical production instead of direct combustion for power generation.
A new process of shale oil and methane cogeneration by oil shale pyrolysis
integrated with pyrolysis gas methanation is therefore proposed. The
pyrolysis gas is first separated to obtain olefins, and then, it is
used to produce methane by methanation technology. This conversion
can significantly improve the energy efficiency and economic benefits.
Technoeconomic analysis shows that the exergy efficiency of the new
process is increased by 14.52% and the return on investment is increased
by 23.33% in comparison with the conventional oil shale pyrolysis
process. The proposed process provides a promising method for the
efficient utilization of pyrolysis gas in the oil shale pyrolysis
industry.
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