Ion liquid desulfurization technology is a new technology for treating Claus tail gas.

1.1 Conventional Process

The process of "Klaus sulfur production + hydrogenation reduction absorption
tail gas treatment" is shown in Figure 1.

1.2 New Process for Treating Claus Tail Gas Using Ion Liquid Desulfurization
Technology

The process of "Klaus sulfur production + ionic liquid absorption tail gas
treatment" is shown in Figure 2.

1.3 Comparison of Processes

1) In the process of “Claus sulfur production + hydrogenation reduction
absorption tail gas treatment”, the regenerated acidic gas from the solvent
regeneration process of Claus sulfur production is H2S; in the process of “Claus
sulfur production + ionic liquid absorption tail gas treatment”, the regenerated
acidic gas from the ionic liquid regeneration process of Claus sulfur production
is SO2.

2) The “Klaus sulfur production + ionic liquid absorption tail gas treatment”
process does not include a tail gas hydrogenation reduction step.

1.4 Technical Advantages of the New Process

1) No Claus tail gas hydrogenation reduction process is required, and no
hydrogen source is consumed; construction investment and operating costs are
lower.

2) Ionic liquids have a very strong ability to absorb sulfur dioxide. The
solvent circulation volume is only 1/15 to 1/5 of that of MDEA solvent. The
utility consumption is much lower than that of MDEA solvent absorption and
regeneration, and the energy consumption is lower, which gives it an advantage
in production cost.

3) The sulfur dioxide concentration in the purified gas after ionic liquid
absorption can be guaranteed to be no more than 50 mg/Nm3, and the sulfur
dioxide recovery rate in the tail gas can reach over 99.5%. If the sulfur
dioxide concentration in the exhaust gas needs to be further reduced, only
appropriate adjustments to the operating parameters are required, without any
modification to the equipment or an increase in production costs.

4) Ionic liquids absorb only sulfur dioxide, eliminating the co-absorption
problem of CO2 by MDEA solvent. This provides unparalleled advantages over MDEA
solvent absorption for treating acidic gases from coal chemical processes with
high CO2 content. It also eliminates the side effects of large-scale CO2
recycling, allowing for smaller equipment sizes and lower construction
costs.

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