Tobacco Documents Online

CHARGE NUMBER : 1804 PROGRAM TITLE : Expande&Tobacco - Process Improvement PERIOD COVERED: July 1-31, 1981 PROJECT LEADER: R. G. IJhl I. TOWER STUDIES (H. Nguyen) The conversion of the 8-inch tower to a rectangular cross-section design (4" x 14") was completed this month. Also, repair of process leaks, lining of the burner firebox and replacement of the C02 storage tank piping were accomplished during this shutdown period. The cross sectional area of the rectangular tower is essentially the same as that of the original 8-inch tower (56 in2). The purpose of the rectangular cross-section is to eliminate tobacco roping in the tower elbows. noted by Project 1801 during studies on Plexiglass test elbows. Rectangular elbows distribute the tobacco along the outside radius wall. This offers the possi- bility of increased heat transfer by exposing the individual tobacco particles to the hot process gas. Expansion trials on the new system have begun. These will determine the effects of gas temperature, gas velocity and feed rate on product parameters. The only other appreciable change in the system was the installation of a venturi feed section. This was intended to provide atmospheric pressure at the tower inlet valve to minimize air leakage into the system. This has altered the tower pressure profile, increasing pressure drop through the expansion loop. A conventional feed section is being made to allow evaluation of the rectangular tower with a.more conventional pressure profile. Subsequent modifications will evaluate elbows of smaller and larger radius of curvature, and will determine the benefits of elbow deflector plates to redirect tobacco away from the elbow waL7l and into the gas stream. The small radius elbows have been fitted with windows to allow evaluation of an infra-red particle temperature sensor by Project 1801. Ceramic lining of the firebox and transition piece into the heat exchanger has apparently allowed a large (100F°) reduction in corepak temperature at the same process gas set point. The retractable arm sparger was installed and evaluated in Phase III. Instrument air pressure was insufficient to operate the pneumatic piston (controlling arm movement) at the low temperature caused by a C02 fill/drain/vent cycle. The arms were successfully operated with the high pressure(2'S0 psi) C02 gas used to actuate the impregnator locking rings. A remaining problem is impregnator pressure (400 psi) blowby of the shaft seal which would cause retraction of the arns during impregnation. Pneumatic piston vent lines are being installed to allow evaluation of the spaLger principle. The gears for slowing down the MC clumpbreakers have been received. The "C" clumpbreaker is being modified first. Other units will be converted as gearboxes are rebuilt.

- 2 - II. HEAT TREATMENT (A. Johnson) Complete results on autoclave heat treatment at 200 and 230°F upheld the preliminary indications. There was no improvement in product color due to nitrogen blanketing during treatment and/or storage, as well as no appreciable effect on CV. Final results confirmed a peak CV attained at 24 hours treatment time. Ii I IT Autoclave treated material was expanded in the 3-inch tower, along with DIET and WET controls. Results showed that tower treatment tended to produce the same product (equilibrium CV/OV = 60/9.0) regardless of autoclave pretreatment time. Increases in CV with tower treatment were 8 units for the 24 hour autocLave product and 15 units following 12 hour autoclave treatment. The 60 CV products were roughly equivalent to previously reported WET results (water expanded without prior autoclave treatment), but the equilibrium CV of 60 cc/10 g is attained at a lower equilibrium OV with the autoclave pretreated product (equilibrium OV 9% vs 11% for WET). Trials are in progress to: evaluate the effect of ammonium tastrate and tartaric acid (5% addition level) in providing a lighter product color. This ensued due to a Project 1503 recommendation based on earlier work on other products. III. PERKS (A. Johnson) Initial groundwork is underway to develop and scale up a continuous version of the PERKS (Peroxide Expanded RRS) process developed by Project 1503. Initial trials have demonstrated a reasonable ability to spray a lime slurry. Mock ADT dryer runs using tobacco wetted to the same process moisture (75% OV) pointed out severe handling problems. Subsequent effort is being directed at reducing excess moisture to facilitate processability. Several small equipment items are on order to insure materials of construction compatable with hydrogen peroxide. Meetings have been held with the Safety Coordinator and in-house advisors to insure that proper procedures are specified. /deb