Issues regarding MTBE desulfurization
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This post was last edited by *aoquanxd on 2015-6-10 17:50. Hello, everyone! Our company has a hydrocracking unit and an MTBE unit. The C4 feedstock from the upstream process passes through a propane removal tower, an ethane removal tower, a propylene removal tower, and an isobutane removal tower before entering the MTBE unit. The isobutane removal tower is used primarily to remove heavier components such as C5 and isobutane; the light C4 components at the top of this tower are pumped into the MTBE unit. The sulfur content in the C4 feedstock entering the hydrocracking unit is around 25 ppm, and that in the MTBE unit is also below 10 ppm. However, recently due to some problems with the isobutane removal tower, operators have to frequently shut down the pump that transfers material from this tower to the MTBE unit, which results in a higher sulfur content in the MTBE product. I would like to know just how much the operation of the isobutane removal tower affects the sulfur content in MTBE
Since sulfur-containing compounds belong to the reconstituted components； In the light and heavy tetrahydrocarbon separation tower, the vast majority of sulfur compounds go along with the pentane and heavy tetrahydrocarbons at the bottom of the tower, thereby ensuring that the MTBE product manufactured using light tetrahydrocarbons has a total sulfur content of less than 10 ppm ； Without the separation provided by the light and heavy tetrahydrocarbon separator, most of the sulfides will enter the MTBE plant along with the mixed tetrahydrocarbons, resulting in an excessive sulfur content in the MTBE.
Strongly agree! The M degassing tower is exactly for this purpose!
After the upgrade of gasoline quality, we refer to the isobutane removal tower as the pre-MTBE desulfurization tower, and the C4 feedstock desulfurization tower
May I ask, what is the feed rate of carbon tetra in tons per hour? What is the flow rate of the vapor at the bottom of the isobutane removal tower? Additionally, does “carbon tetrathiide content in the feed for the gas separation unit” refer to the feed material for gas separation (liquefied petroleum gas? ）?
So that means, if the isobutane separation tower is operated properly, there won’t be any issues with the sulfur content in MTBE, right?
The C4 feed to the MTBE unit is approximately 30 t/h; the C4 in this feed comes mainly from catalytic cracking and coking cracking, and the temperature of the steam used for isobutane removal is 65±5℃
The desulfurization of C4 feedstock involves two steps: first, amine solutions or alkaline solutions are used in a double desulfurization process to remove active sulfur compounds such as hydrogen sulfide and thiol compounds; thereafter, physical separation is carried out using a light and heavy C4 separation tower to remove some of the heavier components, primarily those that are non-active sulfur compounds. Only after that does the material proceed to the MTBE production unit. Since MTBE has a strong adsorption capacity for sulfur-containing substances, it is crucial to properly control the operations in these two steps.