8-952 Rice in Storage T STATIOI SUMMARY Research was conducted at the Rice-Pasture Experiment Station near Beaumont during 7 crop years (1952-53 through 1958-59) to determine the engineering problems and the practicability of dry- ing rough rice in storage in Texas. Drying rice in storage means drying rice in the same bin in which it is to be stored. Rough rice. with initial moisture contents of 15.0 to 23.0 percent. was dried at depths of 4 to 1U feet with both unheated air and air with supple- mental heat. After the moisture content was re- duced to a safe storage level of 12 to l3 percent, it was held in storage in the same bin in which it was dried from 3 to 6.5 months. Drying rice in storage has limitations. How- ever. these tests show that rice can be dried in storage in the rice-producing area of Texas without quality loss, when air flow rates and operating pro- cedures outlined in this bulletin are followed. Building and equipment requirements for dry- ing rice in storage also are given in this bulletin. To prevent loss in grade. milling yields and germination with both unheated air and supple- mental heat. an air flow rate of 9.0 cubic feet per minute (cfm) per barrel (2.5 cfm per bushel) was found necessary to dry rice with an initial moisture content of 2D percent. The maximum depth of rice for the most economical drying was 8 feet at this moisture level. " A simple fan operating schedule. based on pushing air up through the rice. was developed. Loading storage bins to a depth of 2 to 3 feet succession until all storage space was utilized. sulted in the maximum fan capacity on the wett rice. This procedure also resulted in faster dry' and reduced the possibilityof damage from mol Supplemental heat was found to be practi during prolonged periods of high humidity or l in the season during cold weather. The tempe ture of the air entering the rice may be raised above outside air temperature, but should not ceed 95° F. after heating. In unheated air and supplemental heat dry' applications under Texas conditions, the moist in the wettest layer of rice had to be reduced bel l6 percent in 15 days, or less. to prevent loss grade from discolored kernels. Further reductio moisture to a safe storage level of 12.5 percent accomplished over a longer period of time with loss in grade. An air flow rate of 0.4 cfm per barrel (1 / l0 per bushel) was effective for holding undried with an initial moisture content of 18 to 19 perc for 9 days without grade loss from discolored nels. Aeration was effective in maintaining the c dition of rice after it was dried to a safe stor level. Rice in each bin was aerated as often necessary to reduce the temperatures in the rice 60° F. or less. Fans were operated when the outs air temperature was 10° F ., or more. below the av age rice temperature. except during foggy or ra' periods. Fan and air distribution systems used drying also were satisfactory for aeration. CONTENTS Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Fan Operating Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3 L°adin9 Bins - ~ - - - ~ - - - - - - - - - - - - ~ ~ - - - - - - - ~ - - - - - - - - - - Equipment and Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . .. 3 Sfxmpliég for Moisture C°ntent ' ' ‘ ' ‘ ' ' ' ' ' ' ' ' ‘ ' ' ' ' " " '" Storage Bins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4 Drymg with supplemental Heat ' ' ' ' ' ' ‘ ' ' ' ' ' ' ' ' ' ' ' ' ' " " Full-scale Bins . . . . . , . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . .. 4 DrginglEquipmlené"'6'", ~ ~ » ~ ~ ~ - ~ ~ - - ~ ~ ‘ ~ - ~ ~ A - - - ~ - - -- Smdlbscale Bins _ I I _ I I I _ ' ‘ ' _ . ' g t 4 upp ementa eat nits . . . . . . . . . . . . . . . . . .g . . . . . . . _ . _ ' ' ' ' ‘ ' ' . ' ' ' ' ' ' ' ' ' ’ ' ' ' I Air Temperature . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . . . . . . .. Drying with Unheated A1r . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4 Recommendations for Using supplemental DfYlng Wllh suPPlemenlal Heal ~ - ' - - ~ - - ~ - ~ - - - - - - - ' ~ - - -~ 4 Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electric Heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Relatianship of Time‘ Temperature and Gas Heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Moisture Content in Drying . . . . . . . . . . . . . . . . . . . . . . .. Aeration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. B Full-scale Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .._ Quality Determinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6 Small-scale Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6 1957 Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Rice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . .. 7 1958 Tests < - - - - » - - - - - - - - - - - _ - . ~ . - - - ~ - - - - . - - - - . - - - H Results and Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . .. 7 Recfammendatbns ' ' ' ' ' ' ' ' ' ' ' ' " ' " " ' ' " " " " " ' ‘ " " ' " " ' ' ' ' ' " Drying with unheated Air _ _ _ _ _ _ _ . _ _ ‘ _ _ _ _ _ _ ' _ _ _ _ _ _ _ _ _ _ h _ 7 Aeration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . Drying Equipment _ _ _ _ _ _ _ I ' _ ' ' _ _ _ ' _ ' _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ , 7 Quality of Rice Dried in Storage . . . . . . . . . . . . . . . . . . . . . . . . .. Air Flow Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 A¢kn°wled9menls - - - - - - - - - V ~ - - - - - - - - ~ - - - - - , - - - - - - - - - - . .- Depth of Rice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lO References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. THE RICE produced in Texas is harvested combines at moisture contents too high storage. The maximum moisture con- safe storage is 12 to 13 percent. For it is necessary to provide some of drying to reduce the moisture content e storage level. three rice-drying methods used today are ted-air drying; (2) unheated-air drying; drying with low-temperature air, referred bulletin as drying with supplement heat. ted-air drying is the use of forced venti- Qwith the addition of large amounts of heat oving moisture. Unheated-air drying re- __the use of forced ventilation with normal heric air. Drying with supplemental heat ‘Sesame as drying with unheated air except small amount of heat is added to the dry- p to lower the relative humidity during per- ;hen the atmospheric air has a high relative pity. The temperature rise of the drying "illy is limited to 1O to 15°. if, ted air is not recommended for drying A ths of rice, since it results in overdrying p m part and may cause spoilage in the s [iflayers of rice. Commercial rice drying - performed in continuous-flow dryers ing large volumes of heated air through ers of rice (4 to 10 inches thick). Seated air and supplemental heat are suit- drying deep depths of grain. Drying itdepths of 8 to 10 feet is known as bin or drying in storage, since the grain is j the same bin in which it is to be stored. pthod of drying is suited particularly for i installations since the amount of hand- ;reduced to a minimum. However, there in limitations. The most important of weather, since the rate of drying with air depends considerably on suitable I conditions. Drying with unheated air plemental heat isa slow process, but if i, stored for a period longer than is re- or drying, the time element is not im- the past few years, there has been con- . interest in the possibility of drying rice u‘ _. ly, professor, Department of Agricultural En- 9 College Station, Texas; and superintendent, No. 4, Beaumont, Texas. " Drying Rough Rice in Storage J. W. Sorenson, Jr. and L. E. Crane* in storage in the Gulf Coast area. The humid weather conditions exisiting in this area and the differences in varieties and handling practices made it necessary to develop facilities and oper- ating procedures applicable to the rice-producing area of Texas, Figure 1. To fill this need, the Texas Agricultural Experiment Station began re- search in 1952 to determine the solutions to some of the engineering problems and the practicabil- ity of drying rice in storage under Texas condi- tions. This bulletin provides information on equip- ment needs, air flow requirements and operating schedules for drying and storing rice. It includes information on the relationship of drying time to the drying air temperature, moisture content and depth of rice. Information on the effects of drying and storage treatments on the germina- tion, milling yield and other related factors also are provided. EQUIPMENT AND TEST PROCEDURE Rough rice, at different moisture levels, was dried at depths of 4 to 10 feet with unheated air and with supplemental heat at Substation No. 4 near Beaumont, Texas. After the moisture con- tent of the rice was reduced to a safe storage level (12 to 13 percent), it was stored 3 to 6.5 months in the same bin in which it was dried. Results were obtained for 7 crop years, 1952-53 through 1958-59. RIBE-BRBWINB AREA 0F TEXAS LOUISIANA Figure 1. The main rice-producing area of Texas. The heavy black line shows the north and south boundaries of the rice area. 3 Figure 2. These round, steel bins were used in rice dry- ing and storage tests. A supplemental heater is shown on the bin in the foreground. Storage Bins Full-scale Bins Seven conventional farm-type bins and two steel buildings were used in these tests. The conventional bins were constructed of steel, Figure 2. One of the bins was 14 feet in diameter with a capacity of 275 barrels (45,000 pounds). The other six bins were 18 feet in di- ameter with a capacity of 600 barrels (100,000 pounds) each. The 14-foot diameter bin was equipped with metal air ducts to distribute the forced air. The remainder of the bins were equipped with perforated floor drying systems. One of the steel buildings used in the drying tests was 16 x 28 feet long, with a capacity of 600 barrels, Figure 3A. This building was e- quipped with a center duct. The other building, in which four bins were constructed, was 32 x feet long; Figure 3B. Capacities of these b ranged from 500 barrels (81,000 pounds) 1,100 barrels (178,000 pounds). All of the b were equipped with half-round ducts made expanded metal and covered with screen wire Small-scale Bins Eight plywood bins of *12.5-barrel (45 bush capacity each were used in these tests. Each was 21/2 feet square and 101/2 feet deep. A x floor covered with screen wire was installed inches above the bottom of each bin, which,,,,¢ vided a rice depth of 9 feet. All of the binsrw placed in one end of a 32 x 60-foot building the fans located to draw air from the outs Orifice plates were used to control the air rate to each bin. Each bin had thermocou spaced along the vertical centerline at 6 inche p feet and 8 feet from the bottom, Figure 4. S pling ports were installede in each bin near thermocouple locations, Figure 4. Drying with Unheated Air Tests were conducted with small-scale full-scale bins. Initial moisture content of rice was 15.0 to 23.2 percent, wet basis. small-scale bins were used to determine minim air flow requirements for drying with unhe air. Centrifugal and propeller fans were used supply air for drying the rice. All of the f were driven by electric motors. Drying with Supplemental Heat Supplemental heat was used to bin dry with initial moisture contents ranging from to 23.0 percent, wet basis. Electric and gas h Figure 3. These steel buildings were used in drying and storage tests. A. This 16 x 28-foot building was equipped a {an and air distribution system for drying and aerating rice. Samples ior moisture content were taken through sam ports in bin walls. as shown. B. This 32 x BO-ioot building was used for bin drying tests with unheated air and with su mental heat. 4 Lilo 4. Samples of rice were drawn through ports in airmail-scale bins (left). Cross-section of small-scale i ‘ng three levels at which samples were taken e used to heat the air to the desired tem- a e. , Heaters electric heater consisted of six 2,000-watt 0d heaters installed in a sheet metal duct, The duct, with heaters, was connected A j an outlet and the air was heated as it was around the heaters before it passed . y the rice. A~ temperature rise of 10° ‘ined when air was supplied at a rate of m. ree-step thermostat, set for a maximum ture of 92° F., was used to control the ture of the air entering the rice, Figure d operation of each heater Was controlled hunger-type mercury relay. A humidistat i3» to operate the heater when the atmos- ‘relative humidity Was above 75 percent. 2 v2‘ scum RICE 9' DEEP ii ‘.:\...'.......°... ._ .___ ._...___. c. 3' Dgpf“ 9' _._ -...__. 3-". 4' pgpfg _. ,....___. A- s" DEpfH __4 I—$111111'd l PERFORATED | _ FLOOR »i ‘ 4i- k % ORIFICE Gas Heaters An experimental gas heater was constructed, Figure 7. It consisted of a low-pressure, injec- tor-type industrial burner installed directly in the air stream to the intake of the fan. The unit was designed to burn natural or LP gas at a pressure of 8 to 11 inches of water gauge. Safety a controls were used to reduce the danger from fan stoppage and flame failure. These controls con- sisted of a solenoid valve in the gas supply line connected to a thermal element located in the HUMIDSTAT 4000 WATT HEATING UN IT 4000 WATT HEATING 4000 WATT HEATING UNIT UNIT s15» THERMOSTAT Figure 6. Wiring diagram for automatic control of elec- tric heater used in these tests. burner flame, with a “sail” switch located in the fan intake. The electric circuit controlling the operation of the solenoid originated on the motor side of the motor control switch to provide double protection against danger from motor stoppage. The heater operated only when the atmospheric relative humidity was above 75 percent, but it was necessary to light and turn off the burner manually. The BTU input was controlled by the size of the orifice and/or by opening or closing the gas cock valve. Three commercial gas heaters also were used, Figure 8. All three used propane gas. One of the heaters was operated automatically by a humid- ity controller placed on the floor of the air cham- ber underneath a perforated floor in the drying bin. The controller was set to maintain a rela- tive humidity of 65 percent or less in the air chamber. The heater cycled “on and off” to make needed corrections for humidities higher than 65 percent. The other two heaters were semiautomatic in that they were adjusted to pro- vide a fixed quantity of gas and did not cycle “on and off” as the automatically operated heater FAN INTAKE THERMOCOUPLE MOUNTED m euamze FLAME é GAS euawcn a (i?_\ I’ ” A \ U IL TIT“ 31$ U ~:-- ‘———./Z no on 22o vou Pit-OT STAT 1*‘ “‘—‘ sorswoao VALVE, - " I 1 <2 MANUAL CUT- ° l i OFF VALVE 1} I n j "-- ‘ro GAS SUPPLY v SAIL SWITCH ll TO IIO OR 220 VOLT CIRCUIT OR TO MOTOR SIDE OF CONTROL SWITCH Figure 7. Schematic of experimental gas heater, with safety controls, used to dry rice with supplemental heat (l Actual view oi installation is shown at right. When a tan with bearings on the opposite side trom the inlet is used, the q did. A humidity controller was used to ope . these two heaters only when the atmospheric . ative humidity was above 75 percent. All of 5 heaters were equipped with safety controls to l off the gas supply in the event of power or fla failure. _ Aeration Aeration is the movingieof small amounts outside air through stored rice, for purposes ot than drying, to maintain or improve its qual Studies of the effect of temperature moisture content on the quality of undried» g held for various lengths of time in aeratedts age were made with the small-scale bins. B of rice with initial moisture contents of 16 to percent were aerated with air flow rates of and 0.4 cfm per barrel (1 /20 and 1/10 cfm g bushel). Quality Determinations Temperature observations were made at r ular intervals during the drying and storage p iod. Samples for moisture content, milling yie and germination were taken at three levels each bin at the start of drying. These sam were air dried in thin layers and used as che Similar samples were taken after drying and the end of the storage period and compara analyses were made. Instruments A portable potentiometer and copper-const tan thermocouples were used to determine t peratures at various locations in the rice. Brown-Duvel moisture tester was used for I' ture determinations. A deep bin probe was u to obtain samples of rice from the bins. An clined manometer, with scale graduations of tended intake (right) can be eliminated and the flame pointed directly into the fan intake. 6 . fof Water, was used to measure static pres- various depths of rice in each bin. Rice uebonnet 50, Century Patna 231, Zenith, 9 and Rexoro rice varieties were used dur- he 7-year test period. Rice used in these _ either was loaned by farmers in the Beau- area or produced on Substation No. 4. ULTS AND RECOMMENDATIONS Drying with Unheated Air in drying rice with unheated air has ad- over drying with supplemental heat. ted air drying requires less investment in fitment and less attention by the operator, re- fire hazards and usually results in more rice drying. However, there are certain The most important is uncontroll- weather, since the rate of drying with un- air is dependent on weather conditions. - is to be sold soon after harvest, the com- ively long period required for drying with ted air is a disadvantage. In this case, er drying method is advisable. If rice is O for a period longer than is required for g with unheated air, the time element is important. Supervision over a longer period l? e is required when unheated air is used as drying agent. Other important factors de- ‘ning the effectiveness of unheated air dry- he the moisture content and temperature of a . 'ce, depth of rice in the bin and rate and l. rmity of air flow through the rice. Equipment e equipment required for bin drying with ted air consists of a structure for holding ce, an air distribution system and a fan by an electric motor or gasoline engine. concrete or steel bins are satisfactory for rice (1). A tight structure should be pro- prevent air and moisture leakage through l}: floors and walls. Bins should be located ell-drained areas to prevent moisture leak- ,und the floor-wall joints. air distribution system which provides distribution of air throughout the bin be used. Types of air distribution sys- lsed in these tests were perforated floor, uct and lateral, lateral and center duct, l 9. Lateral systems are satisfactory for is and for round and rectangular bins. ted floors are better suited for small di- p round bins than for larger storage struc- center duct is limited to use in a narrow p5: (a width of 16 feet was used in tests) iuires a building with wall openings to uniform distribution of the air through A~ lateral system or a perforated floor ‘fmmended for drying rice in storage. Figure 8. Three commercial gas heaters used in tests at Beaumont. All were equipped with safety controls to cut oif the gas supply in the event of flame or power failure. 7 Centrifugal and propeller fans were suitable for bin drying rice. Centrifugal fans ordinarily used for this method of drying either have “for- ward-curved” blades or “backward-curved” blades, Figure 10. “Forward-curved” fans are lighter and less expensive than “backward-curved” fans. However, with the “forward-curved” fan there is a possibility of overloading the motor if the fan operates against static pressures lower than those used in the design of the system. This is undesirable for bin drying since rice depths vary during the time bins are being filled. A “backward-curved” blade fan has a self-limiting horsepower characteristic, which means that over- loading does not occur in the usual operating range so that it is not necessary to provide motor capacity beyond that required to carry the nor- mal load. The two types of propeller fans used for bin drying are vaneaxial and tubeaxial, Figure 11. A vaneaxial fan consists of a fan wheel within a cylinder with a set of air guide vanes either ahead or behind the fan wheel. It is designed to m air over a wide range of volumes and pressu A tubeaxial fan consists of a fan wheel wit a cylinder without air guide vanes. Its const tion is similar to a vaneaxial fan. The tubea fan is designed to move air over a wide rang volumes at medium pressures. Propeller fans designed to operate aga' static pressures of 3 inches or more usually suitable for drying rice in storage. The ini cost of these fans usually is lower than the i of centrifugal fans. Low initial cost, toget with the small space required and the ease of stallation, are advantages. However, in locati where fan noise is a factor, centrifugal f should be considered. Air Flow Requirements The use of the proper air flow rate to a rice with unheated air is of primary conc Figure 12. Interrelated with the air flow requ ment is the initial moisture content of the i Figure 9. Types of air distribution systems used in the bin drying tests. A. perforated floor: B. main duct and lat C. lateral; and D. center duct. ‘ 8 10. One oi the “backward-curved" centrifugal in these tests. basic drying rate of the rice. Air must be at a rate to complete drying before the damaged by mold growth or other causes. reason, the drying rate in the wettest rice provides the basis for selecting the air flow rate rather than the average observed during the drying operation. um air flow rate of 7.2 cfm per barrel per bushel) was indicated by these tests. was based on favorable weather for and on rice with a maximum moisture of 2O percent. However, this rate should to take into consideration more severe conditions and rice with higher initial content. To insure drying without loss milling yields and germination under weather and moisture conditions oc- Within a season or from year to year, an of 9.0 cfm per barrel (2.5 cfm per is recommended for drying rice in Texas. 20 I0.6 CFM PER BARREL \\ 3-4 CFM PER BARREL \ / \v \ 30 O I 20 30 IO 20 O DAYS DAYS 7.1 CFM PER BARREL l3.S CFM R BARREL PERCENT MOISTURE TOP FOOT OF RICE — WET BASIS I2 O IO 20 30 O IO DAY S DAY S CONTINUOUS FAN OPERATION 20 30 FAN OPERATION ONLY WHEN RELATIVE HUMIDITY WAS BELOW 75 PERCENT Figure 12. Time required to dry an B-ioot depth oi 18- to ZO-percent moisture rice with unheated air in October 1953. Air was supplied at rates oi 3.4, 7.1, 10.6 and 13.5 cim per barrel. Drying equipment dealers and others who se- lect fans for drying rice require information on the total air volume and the static pressure re- quirements. Static pressure is a measure of the resistance that the air distribution system and rice offer to the air flow. It is designated in inches of water. Static pressures against which fans must operate to develop air flow rates of '11. Two types oi propeller ia.ns. The vaneaxial ian (top leit) is designed to move air over a wide range oi vol- static pressures. The tubea.xia1 ian (bottom leit) is designed to move air over a wide range oi volumes at medium A tubeaxial ian installation is shown at right. 9 TABLE 1. STATIC‘ PRESSURES REQUIRED TO DEVELOP DIFFERENT AIR FLOW RATES THROUGH VARIOUS DEPTHS OF RICE‘ Air flow rate Depth of Static pressure, per barrel. rice. inches wa.ter cfm” feet column’ 7.2 8 1.80 10 3.00 9.0 8 2.50 10 4.25 10.8 6 1.80 ~ 8 3.25 ‘Based on data presented by C. K. Shedd (2). “Air flow rates shown correspond to rates of 2.0. 2.5 (Ind 3.0 cfm per bushel, respectively. “Includes an estimated 0.25 inch pressure drop in duct sys- tem. 7.2, 9.0 and 10.8 cfm per barrel of rice are given in Table 1. Depth of Rice The recommended air flow rate of 9.0 cfm per barrel limits the depth of rice t0 a maximum of 8 feet to accomplish the most economical drying. This rate is based on a maximum moisture con- tent of 20 percent. The moisture content of rice, as well as weather conditions, vary from year to year. It is important to provide drying equip- ment of sufficient capacity to insure drying rice without quality loss under the different condi- tions encountered, Figure 13. When the initial moisture content of the rice is above the 20-per- cent level or when the rice is harvested late in the season, the depth of rice should be reduced to obtain higher air flow rates needed for the more severe drying conditions. Recommended depths for drying rice at different initial moisture ranges are shown in Table 2. This is based on the selection of equipment to provide the recom- AIR FLOW RATE O-l QfiM, PCfl BARREL AIR FLOW RATE a4 arm, PER BAHREL I - snnrco mrzmnrzur FAN OPERATION OI G G 5 PERCENT MOISTURE-WET BASIS PERCENT MOISTURE-WET BASIS i = . l Vrocr. 195s I, 5 IO I5 2O 25 3O 35 ‘ 4O O 5 IO I5 2O ems or FAN OPERATION oAvs OF FAN open/argon’ 7 l mended air flow rate of 9.0 cfm per barrel at _ 8-foot depth. Fan Operating Schedule A primary factor in the selection of a fan erating schedule is drying at a rate fast eno to prevent mold development. Another impo i consideration is simplicity of operating inst tions requiring a minimumfcof supervision of drying operation. Other ‘desirable features i fan operating schedule are maximum drying e ciency and use of minimum air flow rates. The direction of air movement through, l has little effect on the dryer performance. 1H ever, it is recommended that air be pushed through the rice for the following reasons: the wettest layer of rice is at the top W sampling is easily accomplished; (2) heat f the motor and fan can be utilized in drying; ; (3) under farm conditions the wettest rice i quently is the first loaded into the bin and first to be dried. The following fan operating schedule is t. ommended in Texas: Start the fan as soon as the air distribu system is uniformly covered with rice. Push through the rice continuously until the moist content of the top foot of rice is reduced to l= 15 percent. After the moisture is reduced this level, operate the fans only when the rela humidity is less than 75 percent (usually du daylight hours on clear, bright days). Conti this procedure until the moisture content of i top foot of rice is reduced to 12.5 percent. T the fan off if heavy rains occur during the riod of continuous fan operation. When ra I - BELOW 60° "m - so°/., TO eo° OCT. 5-I5 (264 HOURS) OCT. 5 - 2s (404 HouRs) SEPT. s-oct. :5 = (984 HOURS) O IO 2O 3O 4O 5O 6O 7O - PERCENT OF TIME Figure 13. These graphs show the effect of weather conditions on the time required to dry 8-foot depths of Century rice with unheated air. Rice harvested in October dried in about one-half the time required to dry rice harvested in Sept ber. This was accounted for by the more favorable weather conditions occurring in October than in September, shown by percent of time the relative humidity was within indicated limits in the graphs on the right. The rainfall was 4.92 inches du lot 10 September and 0.18 inches during the first half of October. There was no loss in grade, milling yields or germination in ei f: - ABOVE so ;last longer than 24 hours, keep the rice operating the fan 2 to 3 hours each day weather clears. m» r drying can be accomplished by loading ibins in layers. This is accomplished by leach bin to a depth of 2 to 3 feet in suc- Then, starting with the first bin, 2 or re added to each bin progressively until p, e storage space is utilized. Equipment loading the bins is shown in Figure 14. this procedure, the maximum fan ca- "n be used on the wettest rice. This will “faster drying and reduce the possibility ior Moisture Content gmoisture content should be checked at rice a Week during the drying operation. should be probed at 8- to 10-feet inter- the surface of the rice and samples rom the bottom, mid-depth and top foot. A each level should be mixed thoroughly oisture check made for each level. low temperatures during drying do not ‘indicate that rice is in good condition, the pulled for moisture content also should o for mold growth. a l ' g with Supplemental Heat Elemental heat is used to improve the ef- i as of unheated air drying systems dur- qnged periods of high humidity or dur- >weather. Drying rice in storage with ntal heat has the following advantages vantages over drying with unheated air. advantage is that drying can be ac- regardless of weather conditions and hatively shorter drying time is needed. tagesinclude the possibility of overheat- ice which may result in overdrying and higher initial equipment costs, closer on and greater danger of fire. l: Q Q cture for holding the rice, a fan and gistribution system as described for bin 'th unheated air are satisfactory for bin "th supplemental heat. In addition, a nit is required to heat the air to the de- L. perature. imental; Heat Units. Electric and gas ere usdd”in these tests. évantages in using an electric heater are li-ricity provides a clean source of heat pols are readily available and easy to in- utomatic operation. However, an elec- has the following disadvantages: it tyre expensive to operate; it necessitates Yiwire and equipment sizes to take» care TABLE 2. RECOMMENDED DEPTHS FOR DRYING* RICE WITH DIFFERENT INITIAL MOISTURE CONTENTS Initial moisture Maximum depth oi content oi rice. rke at start, Operating procedures percent‘ ieet When the top ioot oi rice is reduced to 16 percent mois- ture, more rice may be ad- ded to fill to the recom- mended depths shown be- low. When the top ioot oi rice is reduced to 15 percent mois- ture. rice with a moisture content, oi 16 percent or less may be added to iill the bin to a depth oi l0 ieet. 20 to 22 6 1s to 2o a “A moisture content oi 22 percent is the maximum recom- mended ior drying rice with unheated air. of increased electrical loads when the heaters are used; and it creates high-peak, short-duration loads which may be undesirable in some areas. Natural or LP gas generally is a satisfactofli- source of heat in most areas. One or the other of these gases is readily available; the burners are inexpensive; the operating cost is reasonable; and simple, inexpensive controls can be installed to cut off the gas supply automatically in case of flame, fan or power failure. A semiautomatic gas heater adjusted to pro- vide a fixed quantity of heat was found satisfac- tory for drying rice in storage. The variation in output by the burner was controlled by the size of orifice used and / or by opening or closing a gas cock valve. Semiautomatic refers to a bur- ner that must be lighted and turned on manu- ally, but is equipped with safety controls to auto- matically cut off the gas supply in the event of flame or power failure. Figure 14. Typical scene oi unloading rice irom trucks into storage bins with an auger loader and grain tow board. The pneumatic conveyor, shown in background. also was used ior unloading trucks and storage bins. ll SUPPLEMENTAL HEAT FAN OPERATION 0.2 c.r.u.r>:n “nan. UNHEATED AIR & INTERMITTENT N FAN OPERATION 0.0 emu. run BARIIEL N O ' STARTED TNTERMIYTCNT TAN OPERATION 6 TOP LAYER "\ \ MIDDLE LAvcn *2 U‘) < m r- u B l u] a D +- 2 o 2 I»- z u: u a u: O. PERCENT MOISTURE-WET eixsus LAVER \moou: Luca LAYER muss . was O 5 IO I5 2O 25 O 5 IO l5 2O DAYS OF FAN OPERATION DAYS OF FAN OPERATION Figure 15. Results of drying 8-foot depths of Century Patna rice with unheated air and with supplemental heat are shown in these graphs. Figure 13 shows that weather conditions during these tests were favorable for drying with unheated air. As a result. not much was gained by using supplemental heat. A semiautomatic heater, as described, could be made t0 operate automatically by using a pilot burner and a humidistat set to control the oper- ation at the desired humidity range. With a bur- ner adjusted to provide a fixed quantity of heat, the atmospheric humidity, rather than the hu- midity of the drying air, could be used as a basis for operating the heater. Air Temperature Too high an air temperature Will cause over- drying of rice near the bottom of the bin, result- ing in unnecessary loss in Weight and in quality of the rice, Figures 15 and 16. For example, rice dried at a 10-foot depth With an air temperature of 112° F. (outside air temperature averaged 55° F.) resulted in a reduction of milling yields from 51 to 72 percent at the start of drying to 24 to 71 percent after drying, Table 3. The first figure represents the percentage whole grains or head rice in a milled sample of rough rice. The second figure is the percentage of whole and broken milled grains. Rough rice at a moisture content of 12.5 per- cent is in equilibrium With a relative humidity of 65 percent (1). Therefore, to prevent over- drying, only enough heat should be added to the drying air to reduce the relative humidity to a minimum of 65 percent. A study of the Weather records in the Beaumont area showsthat when the atmospheric relative humidity is 75 percent or above, the air temperature usually is 80° F., or less, Figure 17. Late in the season, the outside temperature may be as low as 40° F. Supple- mental heat is recommended during these periods of adverse Weather. The initial temperature of the air has little effect on the temperature rise necessary to reduce the relative humidity to 65 percent, When the outside air temperature ranges from 40 to 80° F. When the relative humidity of the outside air is 75, 85 or 95 percent, a tem- 12 perature rise of 5, 9 and 12°, respectively, is quired to reduce the relative humidity of the ing air to 65 percent. Based on this informat a maximum temperature rise of 12° is rec mended for drying rice with supplemental in Texas. Recommendations tor Using Supplemental Heat Recommendations for f“ using suppleme heat are as follows: Supplemental heat is not recommended standard practice for bin drying. However is desirable to have equipment available for during adverse weather conditions. This no ally will be during prolonged periods of high midity (above 75 percent). The temperatur the air entering the rice may be raised 12° a LU 23 I I g T s 22 1”‘. MOISTURE CONTENT DURING t; ,/ \ DRYING +5 2, / \\ DEPTH AT START- e FEET o u. yi- UNHEATED AIR n. 2 g6}'\_ SUPPLEMENTAL HEAT (|4° ms: E _ _____ - \ _ ----- SUPPLEMENTAL HEAT 60° ms: 731s ‘i , @ \ ‘ V STARTED mrznmmterqr FAN OPERATI 1 I I ‘ 2 ls ~_ _‘- ‘ ** ‘ l If TY} _£\ \ LU _ ‘E 5 5 ‘\ \ u l6 x‘ x‘ l5 \ \ \- , —SEPT. u |_ l5 v \ U‘) ‘ \\ i "0' l4 REMOVED BURNER an ~~~‘ 2 SEPT. 3 \\ l- l3 ‘u-‘Tx 5 L.---\i-ser 1.9 \___ Si" u l2 7 q: seer so] u] H AUG-B; I956 NOTE! cmctzo neunzs momma cm PER unmet. a o so |oo I50 20o 25o aoo 35o 40o 45o. HOURS OF FAN OPERATION - estow so‘? % - 609010 80% [:1 - ABOVE 80% SEPT. ||- 2e (384 HOURS) AUG. 23- SEPT- 3 (288 HOURS) 4] AUG. aa-sepr. Is (576 HOURS) AUG. 23 -SEPT- 23 (768 HouRs) -—] O IO 2O 3O 4O 5O 6O 7O PERCENT OF TIME PERCENT OF TIME RELATIVE HUMIDITY WAS WI INDICATED LIMITS- I956 Figure l6. The top graph shows the results of tests unheated air and with supplemental heat. The bottom shows the percent of time the relative humidity was indicated limits. Weather conditions during the first p, the drying period were extremely unfavorable for with unheated air. For example. the rainlall was 3.19 i from August 23 to September l0, compared to no r ' from September l1 to September 23. As a result, the time was considerably reduced by using supplemental There was no loss in grade. milling yield or germinati any of these lots of Bluebonnet 5O rice. ‘ABLE 3. EFFECT OF DRYING WITH SUPPLEMENTAL HEAT ON HEAD RICE YIELDS AND GERMINATION =' r . . Average moisture Head rice. Germination. Maxigizetefiiziigture content. percent percent‘ percent drYlngl Start oi End oi Start oi End oi Start oi End oi degrees F- drying drying drying drying drying drying 112 22.3 16.7 51.0 24.0 86.8 82.5 86 17.0 12.1 63.0 64.0 91.3 ’ 93.5 95 18.0 10.6 57.6 61.6 88.6 96.8 90 20.3 11.5 51.3 54.6 84.0 88.2 98 20.5 11.6 52.3 55.6 87.5 85.2 93 21.0 11.1 55.3 60.0 87.0 92.6 90 . 20.6 11.8 60.0 61.0 89.7 92.3 85 21.6 12.6 a 60.0 62.3 45.0 66.0 {air temperature, but should not exceed er heating. Supplemental heat should ntil the moisture content of the top foot freduced to 15 percent. After the mois- ‘uced to this level, use unheated air to he drying to a safe storage level of nt. During the time unheated air is i; te the fan only when the relative hu- less than 75 percent (usually during ,5 hours on clear, bright days). ‘p of Time, Temperature and .-_Moisture Content in Drying fportant consideration in drying rice _,eated air or supplemental heat is the ‘I time permissible to complete drying - A I age from molds or other micro-organic urs. This is particularly important with Dkuse damage from molds usually is as- gwith a discoloration of kernels, com- ed “heat damage” or “stack burn.” ii of “heat damage” on the grade of is shown in Table 4. wer limit of temperature for the growth xtorage molds is about 40° F. and the temperature for growth of most of them 90° F. (3). Semeniuk (4) found that ‘on. relative humidity of 80 percent in his required for continued mold growths. humidity of 80 percent corresponds to rium moisture content of about 15 per- basis, for rough rice at 70° F. (5). ade by Del Prado (6) with rice at tem- ‘_ between 63° and 75° F. show that mold ycreases with increasing moisture con- ‘e 15 percent. ‘Tests jted air drying tests conducted at Beau- A111. full-scale bins, from 1952-57, showed pvnship between the length of the drying “w quality loss as determined by U. S. _'r example, excessive “heat damage” oc- en the moisture content in the wettest ce at temperatures of 80° to 86° F. re- ive 15 percent for 8 to 10 days. On 2nd, rice at 65° to 78° F. was- dried lhtago oi whole grains that a sample oi rough rice yields when milled. during September and October without grade loss when it remained above 15 percent moisture for as long as 15 days. Rice dried during November and December was held above 15 percent mois- ture from 30 to 40 days without quality loss. Rice temperatures during these months ranged from 45° to 55° F. After the rice was reduced to 15 percent moisture, further reduction in moisture to a safe storage level of 12.5 percent was ac-H complished over a longer period of time, without loss in grade and milling yields. The results of these tests support the results obtained by sev- eral researchers (7, 8, 9) and demonstrate the importance of providing adequate drying equip- ment and proper operating procedures to insure drying rice without quality loss under the dif- ferent moisture and weather conditions encoun- tered from year to year. Small-scale Tests In 1957 and 1958, studies were conducted with small-scale bins to obtain additional data on the effect of different air flow rates through stored rice at different initial moisture contents on the quality of rice as measured by U. S. Grade. Samples were pulled periodically at three depths, Figure 4, for moisture determination, milling and germination tests and mold studies. 1957 Tests. Four bins were filled to a depth of 9 feet on September 29 with 16- to 17-percent moisture Bluebonnet 5O rice. Aeration was star- ted immediately after the bins were filled. Air TABLE 4. ALLOWABLE NUMBER OF “HEAT-DAMAGED" KERNELS IN 500 GRAMS FOR DIFFERENT GRADES OF ROUGH RICE‘ Maximum number oi Grade heat-damaged kernels U. S. No. 1 l U. S. No. 2 2 U. S. No. 3 5 U. S. No. 4 10 U. S. No. 5 30 U. S. No. 6 - 75 U. S. sample grade Above 75 ‘From oiiicial U. S. Standards for rough rice. ' 1s was supplied ata rate of 0.2 cfm per barrel (1/20 cfm per bushel) through two of the bins and at a rate of 0.4 cfm per barrel (1/10 cfm per bushel) through the other two bins. Rice in these bins was aerated continuously until January 31, 1958 (4 months’ storage). After that time, the bins were aerated only during the day. The bins were aerated in that manner until the test was terminated on March 1, 1958. Air was pushed through the rice in all of the bins. At the end of the 5-month storage period, moisture content of rice aerated with air sup- plied at a rate of 0.2 cfm per barrel had decreased 1.0 percent (16.2 to 15.2 percent) in the bottom of the bin compared to 0.5 percent (16.5 to 16.0 percent) 8 feet from the bottom. In the bins aerated with air supplied at a rate of 0.4 cfm per barrel, moisture had decreased 2.3 percent (16.1 to 13.8 percent) at the bottom and 1.1 (16.4 to 15.3 percent) at the 8-foot level. Temperatures at the 4- and 8-foot depths were about the same for all bins during the test period, ranging from 3388 --"'TEMPERATURE '—""RELATIVE HUlITY Ali TEMPERATURE -DEGREE$ F RELATIVE I-IUHIOITY- PERCENT moment l, NOON nsounonr TIE --'TEMPERATURE i RELATIVE HUMIDITY AIR TEIPERATURE - DEGREES F RELATIVE HUMIDITY - PERCENT SEPTEMBER 3 6 9 3 6 9 Z O O Z TIME -— HOURS MIDNIGHT MIDNIGHT AIR TEMPERATURE-DEGREES F a high of 77° to 81° F. at the start to a lot 50° to 62° F. at the end of the storage pe Temperatures in the bottom of the bins foll about the same pattern as the atmospheric peratures. There was no loss in germination, grad milling yields in any of the bins during the age period, Table 5. The moisture content of for the two air flow rateslsare shown graphi in Figure 18. 1958 Tests. depth with Bluebonnet 50 rice on Septembe The initial moisture content of the rice {a from 18.4 to 19.3 percent. Unheated air supplied at rates of 0.2 and 0.4 cfm per b‘ through the bins. There were two replica for each bin. Air was pushed through the continuously for 42 days in all of the bins. The moisture content at different depths, corresponding temperatures in the rice, are s in Figure 19. Moisture content and tempera I00 95 ' so - s m / m, 3 as s ‘E In] | '0 I ‘i’ > I r- 4 3 1o f’ ~“’ fi I A? n‘ g ‘g 65$ _l! _‘ E E ‘ E all 59 I —--TEMPERATUR 4 m III-RELATIVE u as \ 1T0?‘ I 1 \ I I I I 5° 3 g 1| I as s s» ‘i E 2 Q 2 is - g a TIME~HOUR$ I00 95 9o I- 65 ‘ 5 ‘\\ I’ u II: 9° \ E >'- 7° \ r t \ 1 o — 1o g , 3 \ _ ---TEMPEI I 65 '1’ x Rmmv: g d" I ‘q t: 6O ,1,’ \\ \ a uovsuecn w; \,_ m §‘ "4, ‘D h_1~ _ Q so E 3 6 9 z 3 5 9 2 3 g Z 5 . TIME-"HOURS Figure 1'7. Average hourly temperatures and relative humidity during August. September. October and November I. Beaumont area, 1948-58. 14. Four bins were filled to a 9i the same time with air flow rates cfm per barrel, respectively, are - 20. y;ure content 0f the rice at the 4- in the low air flow rate bins e 17 percent for most of the test _. *1 re at the 6-inch depth was reduced v6 percent in 18 days (425 hours of if‘ in the bins supplied with air at a if}. per barrel and from 18.4 to 16 _ys (170 hours of fan operation) in 'With air at a rate of 0.4 cfm per pratures at the 6-inch depth were 965° to 77° F. in 2 days (50 hours (on) with both air flow rates. At l, 9 days (210 hours of fan opera- uired to reduce temperatures from ,5, in bins aerated with 0.2 cfm per p? ed to 5 days (125 hours of fan op- i, an air flow of 0.4 cfm per barrel. 7 _rom all three depths in each bin '1 malt-salt agar after surface ster- i’ rmine the number of seeds con- and the changes in prevalence of ies normally present in rice after ' * All species are classified as field exception of those belonging to ofiifliTfiCT OF AERATION WITH AIR FLOW I 0.4 CFM PER BARREL ON MAINTAIN- .’ a OF BLUEBONNET 50 RICE WITH AN r1: CONTENT OF 16.1 TO 16.6 PERCENT. ' 1957-58 0.2 cfm per barrel 0.4 ctm per barrel At After At After start 153 days start 153 days (percent 1115111 16.2 15.2 16.1 15.5 ' m 16.6 16.0 16.2 14.1 16.5 16.0 16.4 15.5 16.4 15.1 16.2 14.6 om 61-10 65-15 62-10 65-12 62-10 65-12 61-10 65-12 62-65 62-12 60-65 62-11 62-10 65-12 61-10 65-12 em No. p 2 No. 2 No. 1 No. 2” In N0. 2 No. 2 No 2 No. 3” m No. 2 No. 2 No. 2 No. 2 I No. 2 No. 2 No. 2 No. 2 ttom 61.5 56.0 56.5 54.0 4m 65.5 55.2 55.5 56.5 I m 87.5 91.7 85.5 92.5 88.2 93.7 85.0 94.3 i for milling yield is the percentage oi Lead rice that a sample of rough rice yields second figure is the percentage of whole led by chalky kernels. %-'e“'ozwrn ----4'0E1>"r11 n . i ,7 ---e DEPTH 2 Avf": ‘ u s 1 \\ .11 ’ 1c p‘ ‘I - '°" “v.3 é ~°___d \‘\ a F;&_,_-o- b\y'l ,0 \ 3 i \‘\ l‘ \ I’ 5 1 ‘~ ,5 . \/ \/_'“\I 5 8 14 l! l!" ".1997 uullcu nee |5I/— I 7 0 400 e00 1200 1600 2000 2400 2500 5200 nouns OF FAN OPERATOON ‘ I is" 059111 _---4' DEPTH g n [K51 _--_a' 025m < l \ m I t’ p ‘i’ “’“"°"&\ 1:4\~a .. fi 5 ‘5 I?" \“_<§/ \ l B ~_@¢O~____ \ e l 2 “\ \/ l ° 15 ~ -A z \ _ \D-Q 9 1i A \\ II 1'1 1- n\ iii / - K“: 8 I I "if x 1- \/ / vs l: SCPTiIS, ti‘! IAIONII, I§O_\ o 400 600 1200 1600 2000 2400 2000 3200 HOURS. OF FAN OPERATION Figure 18. Moisture content of rice with an initial mois- ture content ot 16.0 to 16.7 percent during 5-months'-aera- tion with air supplied at rates 0t 0.2 cfm per barrel (top) and 0.4 cfm per barrel (bottom). There was no loss in grade or germination during the 5-month storage period.‘ the genera Aspergillus and Penicillium. Species of the latter genera have been found to invade cereal grains of all types and have caused de- terioration during storage While infestation by most of the other species found in grain occurs in the field prior to harvest. Field molds were isolated from 99 to 100 per- cent and storage molds were isolated from 0 to 2 percent of the kernels in the initial samples from all four of the low air flow rate bins taken at the time the bins were filled. After 9 days of fan operation with air supplied at the rate of 0.4 cfm per barrel, storage molds Were isolated from 24 percent of the kernels from the 6-inch level; 38 percent of the kernels at the 4-foot level; and 58 percent of the kernels at the 8-foot level. This compares to 25 percent at the 6-inch level, 33 percent at the 4-foot level and 82 percent at the 8-foot level in the samples pulled on the same day from the bins receiving air at the rate of 0.2 cfm per barrel. Storage mold invasion of the rice during the storage period reached a maximum of 64 percent at the 6-inch level, 89 percent at the 4-foot level and 81 percent at the 8-foot level in the 0.4 cfm 15 per barrel bins‘ compared to 73 percent at the 6-inch level, 86 percent at the 4-foot level and 96 percent at the 8-foot level in the 0.2 cfm per barrel bins. The increase in percent of kernels from which storage molds were isolated was highly significant among both days in storage and depths of the rice from which samples were taken at both air flow rates. There was no grade loss at the 6-inch depth in any of the bins, but considerable damage oc- curred at the 4- and S-foot depths with both air flow rates. Figure 21 shows the extent of dam- age occurring at various depths. Moisture con- tent, grade and milling yields taken at intervals during storage are given in Table 6. Recommendations Results of tests with small-scale and full-scale bins emphasize the importance of the time-tem- perature relationship in reducing the moisture content of rice below 16 percent. In unheated air and supplemental heat drying applications under AIR FLOW RATE 0.2 C.F.M. PER BARREL s" rRou aorrou 4' FROM aorroul —- -—- a’ FROM aorrou -—--- IIO 5 o 8O 7O SO PERCENT MOISTURE-WET BASIS TEMPERATURE IN RICE-DEGREES F 1:91.", nu out". IIII 5O O ZOO 400 GOO GOO IOOO O ZOO O00 GOO BOO IOOO HOURS OF FAN. OPERATION AIR FLOW RATE 0.4 C.F.M. PER BARREL s" rnou aorrou 4‘ mom aorrou —— e’ Faom aorrou -—--- IIO IOO 90 / 8O 7O 6O PERCENT MOISTURE-WET BASIS TEMPERATURE IN RICE-DEGREES F. nn. n, Ina nrv.|s_ Ian 5O O ZOO 400 GOO BOO IOOO O 200 400 GOO B00 IOOO nouns or rm OPERATION Figure 19. Moisture content at three depths with cor- responding temperatures for 18- to 19-percent moisture rice aerated 42 days with air supplied at rates of 0.2 cfm per barrel (top) and 0.4 cfm per barrel (bottom). 16 Texas conditions, the moisture in the we layer of rice at temperatures of 70° to 75 must be reduced below 16 percent in 15 day less, to prevent grade loss from discolored nels. Further reduction in moisture to a storage level of 12.5 percent was accompli over a period of several weeks in the Beau area without grade loss. the past 7 years indicatef-a minimum air rate of 9.0 cfm per barrel‘(2.5 cfm per bus to insure drying without loss in grade and A ing yields under the different weather and ture conditions occurring within a season from year to year. f An air flow rate of 0.4 cfm per barrel effective during September and October for ing undried rice with an initial moisture con of 18 percent for 9 days without grade loss f discolored kernels. The quality of rice with initial moisture tent ranging from 16.2 to 16.7 percent was AIR FLOW RATE 7.2 C.F.M. PER BARREL s" mom aorrom 4' mom aorrom --—- a‘ FROM aorrou ———— -- IOO (L; u.’ 1D '3 wso i m W X a: \ I? 8 / T Tao 5g p) u III 4 g 2 / l- “ ‘\ I ‘\ ll I" z I \ / 6 G70 \ I E b g I‘ ‘o4 I- 3 t " I- 5 < ‘=60 O K It‘ a‘ 2 lA-I slqr. n, nu I- n" . 10,0“ ocv. II,I 5O ' O IOO 200 300 400 O IOO 200 300 HOURS OF FAN OPERATION AIR FLOW RATE 9.5 0.5M. PER BARREL s" FROM aorrom 4' FROM BOTTOM -— —- a‘ mom aorrom ---- -- IOO <2 u.' (2 8 9O m u: I .- 5 l. A U] u; ‘c! 3 o \ .. I I 8O u u \ ‘5 ‘i I’ s, ‘é I Y7 '6 — 70 I ‘s’ p- D = z I" u: so u u: I! a. "J 2 “- h.) scar. IOJIQI ;_ sin u, nsl ocmmo I l UI O o I00 20o 30o 40o o I00 20o 500 HOURS 0F FAN OPERATION Figure 20. Moisture content at three depths wi responding temperatures tor rice dried with unheat supplied at rates of 7.2 cfm per barrel (top) and 9.5 c barrel (bottom). Tests conducted I 5 months ‘(September 29, 1957 to ___§i $323322 958) with aeration at air floW rates "m" '“°" “m” 0.4 cfm per barrel. AERATION a in these tests was held in storage bin in which it was dried from 3 to RATE I/20 PER AIRFLUII RATE l/IO e each bin was aerated as often as ;~ reduce the temperatures in the rice r less. Fanswere operated when the tjtemperature was 10° F. or more be- rage rice temperature. Fans were f» during foggy or rainy periods. Con- tomatic operation of fans are shown Le’- , o i; o IO 2o so 4o so NUMBER OF HEAT DAMAGED KERNELS IN 500 GRAMS NUMBER OF HEAT DAMAGED KERNELS IN 500 GRAMS ‘gum air flow rate of 0.2 cfm per bar- DAYS °F 5mm“ - in ended for aerating rice 1T1 commer- Figure 21. Number of heat-damaged kernels in samples 7e; (10). Fan and air distribution sys_ of ricie éaken at diffftelrzent levels from bins aerated with air >fer drying the riee in these teete eup- fiiiiiiailiffwsiiiiiqi $21.53’. bfililfidit K-‘fleggifflllviii 8 higher rate, but also were sat1sfac- with corresponding temperatures are shown in Figure 19. ' ation. With the high air flow rates ng, rice was cooled much faster than y» with the low air flow rates recom- commercial storages. For this rea- iupervision is required when high air air also gives an opportunity to smell the air coming out of the bin to detect any off odor i are used to prevent large weight which may ha“? deheloped‘ In bin drying’ rice 1,, by exeeeeive reduction in the mois_ 1S dried _by pushing air up. Therefore, when bins =t of the rice_ are equipped with drying systems, it is advan- tageous to push air for aeration since it would = rpllshed 11D and Pulled dPWII through be unnecessary to reverse the fan to change the ~ Both methods were effective in reduc- direction of air flow, .tures in the rice. Pulling air down ieensation 111 the Wllltel’. 'I_‘he humid . IN 1' the rice does not come in contact ll surface rice or the cool bin roof. The effect of drying and storage conditions condensation was not a problem when on germination, milling yields and U. S. Grade ISTURE CONTENT, GRADE AND MILLING YIELDS OF SAMPLES OF HIGH-MOISTURE BLUEBONNET RICE TAK- ‘n: LEVELS FROM BINS AERATED WITH AIR SUPPLIED AT RATES OF 0.2 AND 0.4 CFM PER BARREL, 1958‘ Moisture content, percent Grade and percent milling yields” Length of storage, days Length of storage, days At At sum 9 16 30 38 42 start 9 16 30 38 42 I ol No. 3 No. 3 No. 4 No. 3 No. 4 No. 3 ~- bottom 18.9 17.1 16.1 15.8 15.3 14.3 66 - 73 66 - 73 64 - 71 62 - 71 67 - 74 59‘ - 70 1 No. 4 No. 4 No. 4 No. 4 No. 5 Sample 1' ' bottom 18.7 18.0 17.8 17.4 17.0 16.4 65 - 73 66 - 73 62 - 72 62 - 71 66 - 74 59 - 71 No. 3 No. 4 Sample Sample Sample Sample ghottom 18.4 19.4 17.9 17.4 17.5 17.4 65 - 72 65 - 73 63 - 71 61 - 71 65 - 73 59 - 71 el ; No. 3 No. 3 No. 2 No. 3 No. 3 No. 3 ' bottoin 18.6 15.9 15.5 14.4 13.0 13.1 64 - 71 66 - 73 61 - 71 63 - 72 67 - 73 59 - 70 ".. 3 No. 3 No. 4 No. 2 No. 4 No. 3 Sample bottom 18.7 18.0 17.5 17.3 17.3 15.7 65 - 73 66 - 73 61 - 71 62 - 72 67 - 74 65 - 73 j No. 4 No. 4 No. 5 Sample Sample Sample A bottom 18.8 18.5 17.5 17.4 17.6 16.4 65 - 73 62 - 69 62 - 71 64 - 71 65 - 73 60 - 71 l‘ harvested from a field of down rice caused by a hurricane about a week before it was harvested. Some water l in the field during the harvesting operation. As a result, samples taken as the rice was received from the field "damage" and caused reduction in grade as shown above at the start of drying. “Heat damage" and/or musty grade factors causing a further grade reduction. y’ ~ shown for milling yield is the percentage of whole grains or head rice that a sample of rough rice yields when iocond figure is the percentage of whole’ and broken grains. 17 aeration was started early in the season. Pulling Figure 22. Two sets of controls tor automatic operation of tans during aeration. Humidistat (H) and temperature control (T) permitted the fan motor to operate only when the temperature and relative humidity were below the de- sired level. A time meter (M) was used to register the hours of Ian operation. The toggle switch (S) was used for manual control. Wiring diagram for automatic control of fan motors equipped with magnetic starters is shown at right. are shown in Tables 7, 8 and 9. The losses in germination and milling yields during the first 3 years of the tests were attributed to the lack of established operating procedures and the low air flow rates used for drying. With the estab- lishment of minimum air flow rates and im- proved operating procedures, rice was dried and held in storage for 4 to 6.5 months, from 1955-58, without loss in germination or head rice yields. Therefore, rice can be dried in storage in the Texas rice-producing area without quality loss when air flow rates and operating procedures outlined in this bulletin are followed. Frequent inspection of the rice during drying and storage is required to insure maintenance of quality. In these tests, the moisture content and condition of the rice was checked at least twice a week during the drying operation. The rice was probed at 8- to 10-foot intervals over the sur- '1 | I I I I | I I a 1 | | | I HUMIDISTAT ltx I 8N (D l TEMPERATURE l CONTROL -—--_-11¢- uiii-i-ii-i-Qiiiii- C- HOLDING COIL OL'-OVERLOAD SWITCH H-I,H-3 HEATERS TO ACTUATE OL S- TOGGLE SWITCH - SINGLE POLE, DOUBLE THROW, CENTER SWITCH POSITIONSZ l-AUTOMATIC CONTROL 2- OFF 3-MANUAL CONTROL face of the rice and samples drawn from the tom, at mid-depth and the top foot. Rice f each level was mixed thoroughly and a mois check made for each level. taken once a month during the period the remained in storage after it was dried to a t ture content considered safe for storage. ACKNOWLEDGMENTS The following cooperators contributed -. ials and equipment for these tests: Aerovent and Equipment Company, Lansing, Michi Agri-Tec Steel Corporation, J ohnstown, l, Division of Agricultural Engineering, Agr tural Research Service, U. S. Department of riculture; Black, Sivalls and Bryson, Kansas I Missouri; Butler Manufacturing Company, I sas City, Missouri; Lewis S. Doherty Ventila Similar samples ~ Company, Baton Rouge, Louisiana; Farm F i Inc., Indianapolis, Indiana; The McRan Comp Houston, Texas; and Stran-Steel Corpora. Detroit, Michigan. TABLE 7. AVERAGE CHANGE IN GERMINATION OF RICE DRIED WITH UNHEATED AIR AND STORED 3 TO 6.5 MO 1952-1958 Number Len~ ‘h Average moisture Average i {g content, percent germination, percent Average ch Year b? o during - » ms 5t°r“9°' Start of End oi Start of End of and star “heckedl m°nth5 drying storage drying storage 1952 2 3.0 19.3 13.5 89.1 87.9 -1.2 A 1953 3 3.0 19.1 12.0 91.3 90.6 -0.7 1954 6 4.0 18.5 11.4 81.2 80.3 -0.9 1955 5 5.0 17.5 11.2 84.2 85.7 +1.5 1956 6 6.5 18.0 11.2 84.0 93.5 +9.5 1957 10 4.5 17.0 11.9 86.6 94.9 +8.3 1958 9 4.0 18.2 12.5 71.2 73.5 +2.3 ‘Samples for moisture and germination tests were taken at three levels from each bin at the start of drying. These sa were air dried in thin layers and used as checks. period and comparative analyses were made. 18 Similar samples were taken after drying and at the end of the st 1GB CHANGE IN MILLING YIELDS OF RICE DRIED WITH UNHEATED AIR AND STORED 3 "TO 6.5 MONTHS. 1952-1958‘- 1_ Len 1h Average moisture Head rice, Total rice Averageichange during or o? content, percent percent’ percent“ drying’ and storage d1 513999’ Start of End oi Start of End oi Start of End oi Head 1 A Total ‘I m°nth5 drying storage drying storage drying storage rice rice 3.0 19.3 13.5 46.5 45.5 72.0 1 72.0 ‘ —1.0 » 0 3.0 19.0 12.2 57.0 58.3 68.4 69.8 .. +1.3 _ ' 1 ' +1.4; 4.0 18.5 11.4 55.8 55.5 . 63.5 63.8 -0.3 -+0.3 5.0 17.5 11.3 57.6 59.1 67.8 661.9 +1.5 —'0.9 6.5 18.0 11.2 51.5 54.0 69.8 69.7 ' A +2.5 A "-0.1 4.5 I 17.0 11.9 61.5 61.2 70.0 70.5 +0.6 +.05 4.0 18.2 12.5 56.8 57:8 69.6 69.4 +1.0 —0.2 1 lllure content and milling tests were taken at three levels from each bin at the start of drying. These samples ‘ ~- ative analyses were made. p; i of whole grains that a sample oi rough rice yields when milled. o! whole and broken grains. rs express their appreciation for the REFERENCES ‘U the following individuals: M. M. ubstation N0, 4, Beaumont, for his (l) M-ii- Research on CDTIditiOTI- conducting the tests; H_ W_ Schr0e_ ing and Storage of Rough and Milled Rice. thologist, Quality Maintenance and A-RS 20-7. Agricultural Research‘ Service, it Section, Biological Sciences Branch, in thin- layers and used as checks. Similar samples were taken after drying and at the end of the storage pe-. U. S. Department of Agriculture. Novem- 1? esearch Division, Agricultural Mar- ber 1959- .,» U- S; Department Oflpfigrlculture» (2) Shedd, C. K. Resistance of Grains and '1 studies; on mold actlvlty? W- C- Seeds to Air Flow, Agricultural Engineer- 1- ly superintendent,_ and S. R. Mor- 111g 3416164519, 195:1 1y agricultural engineer, Substation _ _ _ ‘Ont; and John (jowsar, formerly 3g- (3) Christensen, Clyde M. _ Deterioration of ti: neer, Department of Agricultural StOIIGd Grains by Fungi. The Botanical $,_College Station, Texas. Reviewigggol. 23, No. 2, pp. 108-134. Feb- : . ' r r . l: s were conducted at the Rice-Pas- ua y _ y. ent" Station, Beaumont, which is (4) Semenluk, G": Anderson, J - 8-, and Alcock, pited by the Texas Agricultural EX- A. MICFOflOTa in Storage O1: Cereal ‘tien, Texas Rice Improvement AS- Grains and Their Products. American As- - 1'U. S. Department of Agriculture. gociatian '1); 1(ge1re%lt(]r11err111%t/;Is_. Moinoglrggigi _; a A eries : - . . au , inneso a, . 511112115 éiiggaiéifirgngil; 111%? 12321155181111? (5) Karon, M._I_.. and Adams, M. E. Hygro- "HEAT-DAMAGED" KERNELS. 1953-1958 ggllléglbgfiglngfirfilgz .aI1(_11; 11g 415mm Number of "umbeeeteemeéee (s) Del Prado, F. A. and Christensen, c. M. lcicatiorés "dgjjdkjnhfg? e Grain Storage Studies XII. The Fungus ° °° e damaged kernels Flora of Stored Rice Seed. Cereal Chemis- 20 12 try 20: 246-462, 1952. 1 113g (7) rljlgiéczr1ofibli. _Minimum A_ir FloW_Require- 32 0 _ ying Grain With Unheated Air. 4g 121 (8) Algrigultural élngéneergig 680-684, 1953. 3 5 en erson, . . eep- ed Rice Drier P f . A ' lt l ' ' ia32.3?“£°.1?§;Z.LT§°Z.S‘1JZ}Z 12%;’; e5? $56358? ieeegm“ 1E“g‘“ee““g lteheehhgcezlipl; vrvlgfe vtvdxksen alahtliearbgxtllld: and (9) Teter’ and Boaner _C~ W- _ MQIdS 1H1- 0 samples were air dried in thin layers and p086 LlmltatlOflS 111 Grain Drying. Agn- Similar eemielee Were taken efler drYinq cultural Engineering 39: 24-27 1958. l‘ 0 analyses ifivere made. ) . i ’ equate an’ ew- __ m (10 . Aperation of Grain in .9.":‘:1Z? gyiglqgruzfiefiuiflfg fijflgfiamaged Commercial Storages. Marketing Research _ ade caused ‘by low rate of air flow and peei- Report No. 178. Agricultural Marketing a dU.S.N.2 dU.S.N.3. - - i-l figgfiimaged" kzrnells? Both samlles rgerscrlzieecd i . ?9eg)7artment of Agnculture‘ September l’ '1' drying. - 19 Service, Marketing Research Division, U. S.. i MAIN srmnow p TAES SUBSTATIONS i TAB new LABORATORIES A COOPERATING STATIONS Location oi field research units oi the Texas Agricultural Experiment Station and cooperating agencies IN THE MAIN STATION, with headquarters at College Station, are 16 s matter departments, 2 service departments, 3 regulatory services administrative staff. Located out in the major agricultural areas oi Te 21 substations and 9 field laboratories. In addition, there are 14- coo stations owned by other agencies. Forest Service, Game and Fish Commission of Texas, Texas Prison U. S. Department oi Agriculture, University oi Texas, Texas Techno College, Texas College oi Arts and Industries and the King Ranch. experiments are conducted on farms and ranches and in rural homes. ORGANIZATION THE TEXAS STATION is conducting about 400 active research projects, in 25 programs, which include all phases of agriculture in Texas. these are: Conservation and improvement of soil Beef cattle Conservation and use of water Grasses and legumes Grain crops Cotton and other fiber crops Vegetable crops Citrus and other subtropical fruits Fruits and nuts Oil seed crops Ornamental plants Brush and weeds OPERATION Insects Two additional programs are maintenance and upkeep, and central s Research results are carried to Texas farmers, ranchmen and homemakers by county agents and specialists ofithe Texas Agricultural Ex- tension Service 3 ’ l? ’ oclag 5 Q5QCCPCA ~96 jOITlJIlO/‘POLU 6 POQPQJ State-wide Researc The Texas Agricultural Experiment Stati is the public agricultural research agent oi the State oi Texas, and is one oi t parts oi the Texas AcSM College Syste Cooperating agencies include the, Dairy cattle Sheep and goats Swine Chickens and turkeys Animal diseases and paras Fish and game Farm and ranch engineerin Farm and ranch business Marketing agricultural pro Rural home economics Rural agricultural economi Plant diseases AGRICULTURAL RESEARCH seeks the WHATS. the WHYS. the WHENS. the WHERES and the HOWS oi. hundreds oi problems which coniront operators oi iarms and ranches, and the many industries depend- ing on or serving agriculture. Workers oi the Main Station and the iield units oi the Texas Agricultural Experiment Station seek diligently to iind solutions to these problems. .