Page 26 - Microsoft Word - Sulfo and Sulfa 1.doc

Figure 24 shows a Chemithon Annular Film Reactor. This patented reactor [10, 11, 12] is
unique in many ways. It employs interchangeable, factory calibrated organic metering
flanges. These flanges ensure that the flow of organic to any two points on the reaction
surface is equal, within ±1%. When combined with the geometric design of the reactor
that similarly controls the flow of SO to the reaction surfaces, these features ensure that
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mole ratio control is maintained on a micro scale throughout the sulfonator. Cooling
jackets on the reactor remove most of the heat of reaction. Additionally, the patented
recycle system allows the reactor to overcome the increase in viscosity of the sulfonic
acid as its level of sulfonation increases. The product exiting the reactor is instantly
quench cooled by removing the acid, pumping it through a heat exchanger to cool, then
returning it to the bottom of the reactor. This cooling process reduces the time that the
sulfonic acid is held at an elevated temperature and results in better product quality. A
side benefit is that the reactor is more compact – less than two meters in height – and
therefore considerably less expensive to install.

Figure 25 shows this reactor installed in a typical sulfonator. Upon exiting the reactor,
the spent gas is separated from the sulfonic acid recycle stream in the liquid separator and
cyclone vessels. Sulfonic acid product discharges from the recycle stream at a controlled
rate, maintaining continuity of the quantity of material in the reactor system. The acid
product from the reactor can then be fed directly to the digestion and hydration system
(or optional degasser system) where reaction with absorbed SO is completed. Hydration
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water is injected and mixed with the sulfonic acid, leaving the digesters to remove
anhydrides.

Figure 26 shows a typical multi-tube sulfonation reactor [9, 13, 18] . The multi-tube reactor is
the other commonly employed film sulfonator design. In this reactor the organic feed is
distributed among a number of parallel reaction tubes, 25 mm in diameter, 7 meters long.
The tubes are arranged like the tube bundle in a vertical shell and tube heat exchanger.
The organic and SO gas flow concurrently down the reactor tube, react and exit the
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bottom of the reactor into a separator vessel. The heat of reaction is removed by cooling
water which flows through the reactor jackets. The approximate residence time of the
acid from the top of the reactor through the separator and cyclone and to the neutralizer is
two to three minutes.

Page 25 of 36 © 1997 The Chemithon Corporation