598
Ind. Eng. Chem. Prod. Res. Dev. 1985, 2 4 ,
ner-type low-pressure mercury lamp in the same manner as the photocycloaddition reaction procedure described above. Isolation of B-Truxinic Acid (17). The mixture of the photoadducts obtained by the irradiation of 1.18 g (4.2 mmol) of cinnamic anhydride (13a) with the light of a high-pressure mercury lamp was refluxed in an aqueous sodium carbonate solution (8%, 100 mL) for 2 h. After the solution was cooled in an ice bath, it was acidified with aqueous hydrochloric acid and extracted with benzene. The benzene solution was dried over sodium sulfate and evaporated, and the residue was recrystallized from benzenefcyclohexane to give dicarboxylic acid (17): yield 0.062 g (12%); mp 201-204 "C, lit. (Coffey, 1967) 210 "C; IR (KBr) v 1710 and 1695 cm-'; lH NMR (Me2SO-d6)6 3.80 (2 H, pseudo d, J = 6 Hz), 4.20 (2 H, pseudo d, J = 6 Hz), 7.0-7.1 (10 H, m), and 12.4 ( 2 H, s). Preparation of 4-Methoxy-4'-nitrostilbene (15d). 4-Methoxy-4'-nitrocinnamicanhydride (13d) (0.24 g (0.68 mmol)) was dissolved in 400 mL of acetonitrile and irradiated with the light of a high-pressure mercury lamp for 10 h. After the removal of the solvent under reduced pressure, the residue was dissolved in benzene (400 mL) and irradiated with the light of low-pressuremercury lamp for 4 h. Evaporation of the solvent followed by separation by column chromatography (Wako gel C-200, 3 cm X 15 cm) with an eluent of benzene gave 0.023 g (0.09 mmol) of 4-methoxy-4'-nitrostilbene (15d): yield 13%; mp 138-138.5 "C; IR (KBr) v 2820, 1600, 1590, 1575, 1510, 1465, 1340, 1260, 970, and 845 cm-'; 'H NMR (CDCl,) 6
598-603
3.85 (3 H, s), 6.93 (2 H, d, J = 9 Hz), 7.01 (1 H, d, J = 16 Hz), 7.23 (1H, d, J = 16 Hz), 7.50 (2 H, d, J = 9 Hz), 7.60 ( 2 H, d, J = 9 Hz), and 8.20 (2 H, d, J = 9 Hz).
Literature Cited Anet, R. Can. J . Chem. 1962, 4 0 , 1249. Ciamician, G.; Silber, P. Chem. Ber. 1902, 3 5 , 4128. Coffey, S . "Rodd's Chemistry of Carbon Compounds I1 Part A", 2nd ed.; Elsevier: Amsterdam, 1967; p 102. Fries, K.; Klostermann, W. Justus Liebigs Ann. Chem. 1908, 362, 1. Hasegawa, M.; Arioka, H.; Harashina, H.; Nohara, M.;Kubo, M.; Nishikubo. T. Isr. J . Chem., 1985, in press. Hasegawa, M.; Saigo, K.; Katsuki, H.; Yonezawa, N.; Kanoe, T. J . Polym. Sci., Polym. Chem. Ed. 1983, 21, 2345. Kopp, K. Justus Liebigs Ann. Chem. 1893, 2 7 7 , 339. Krauch, C. H.; Farid, S.;Schenck, G. 0. Chem. Ber. 1966, 99, 625. Lewis, F. D.; Howard, D. K.; Oxman, J. D. J . Am. Chem. SOC. 1983, 105, 3344 and cited therein. Lin, S.-F.; Connors, K. A. J . Pharm. Sci. 1981, 7 0 , 235. Oppolzer, W. Acc. Chem. Res. 1982, 15, 135. Perrin, D. D.; Armarego, W. L. F.; Perrin, D. R. "Purification of Laboratory Chemicals", 2nd ed.; Pergamon Press: Oxford, 1980. Saigo, K.; Yonezawa, N.; Sekimoto, K.; Hasegawa, M.;Ueno, K.; Nakanishi, H. Bull. Chem. SOC.Jpn. 1985, 58, 1000. Schaumann, E.; Ketcham, R. Angew. Chem., Int. E d . Engl. 1982, 21, 225. Schuitz, W. J . Phafm. Sci. 1963, 5 2 , 503. Toibert. L. M.; Ali. M. E. J . Am. Chem. SOC. 1982, 104. 1742. Wood, J. H.;Bacon, J. A.; Meibohm, A. W.; Throckmorton. W. H.; Turner, G. P. J . Am. Chem. SOC. 1941, 6 3 , 1334. Yonezawa, N.; Hasegawa, M. Bull. Chem. SOC.Jpn. 1983, 5 6 , 367. Yonezawa, N.; Ikebe, Y.; Yoshida, T.; Hirai, T.; Saigo, K.; Hasegawa. M. Bull. Chem. SOC.Jpn. 1984, 5 7 , 1608. Yonezawa, N.; Yoshida, T.; Hasegawa, M. J . Chem. SOC.,Perkin Trans. 1 1903, 1083. Zagorevskii, V. A.; Sarel'ev. V. L. J . Gen. Chem. USSR (Engl. Trans/.) 1964, 3 4 , 2302.
Received for review December 4, 1984 Accepted July 8, 1985
Pilot-Plant Production of Ammonium Polyphosphate Sulfate Suspension Fertilizers Horace C. Mann, Kenneth E. McGIII, and Mark T. Holt' Tennessee Valley Authoriw, National Fertilizer Development Center, Muscle Shoals, Alabama 35660
TVA is developing a process for production of ammonium polyphosphate sulfate (APPS) suspension fertilizer from merchant-grade wet-process phosphoric acid, 93 % sulfuric acid, and anhydrous ammonia. The two acids are simultaneously ammoniated in an "enlarged" pipe-cross reactor: the molten APPS is dissolved in water, and the fluid then is cooled to room temperature in an evaporative cooler. Attapulgite clay is mixed into the APPS fluid to prevent solids from settling during shipment, storage, and use. The process is energy efficient in that the hot APPS fluid provides all the heat required to preheat the phosphoric acid and vaporize the ammonia. Satisfactory suspension grades up to 11-30-0-3s can be made with 50% of the PO , , present as polyphosphate. The sulfur present in the product should be useful either to reduce sulfur deficiencies in the soil or to provide maintenance dosages of sulfur. The APPS fluid fertilizer can be either applied directly to the soil or used in preparation of mixed suspension products of various ratios.
In an attempt to lower the cost of phosphate in fluid fertilizers, the Tennessee Valley Authority (TVA) has continually explored methods for using relatively inexpensive merchant-grade orthophosphoric acid as the source of Pz05in production of fluid fertilizers. As a result of these studies, in 1974 a demonstration-scale plant to produce 13-38-0 ammonium orthophosphate suspension was placed in operation (1-3). This product has been well-received by the fertilizer industry, but the suspension solidifies in very cold weather a t a temperature of about 20 O F . Because of this characteristic, 13-38-0suspension
is used primarily in the southern United States. In 1981, a TVA demonstration-scale plant was placed in operation to make a 9-32-0 (4-7) ammonium polyphosphate (APP) suspension that had improved cold-weather storage properties which allowed it to be stored and used in all areas of the United States. Because of the relatively low total plant food content of 9-32-0 suspension, it was designed to be made in small regional plants where the suspension would not have to be shipped long distances. In an effort to increase the polyphosphate content of suspensions made from merchant-grate wet-process acid,
This article not subject to US. Copyright. Published 1985 by the American Chemical Society
Ind. Eng. Chem. Prod. Res. Dev., Vol. 24, No. 4, 1985 599
PIPE
CROSS REACTOR
A+
n- i",
11-
0-0
APPS SUSPENSION (2% CLAY)
Figure 1. Flowsheet of pilot-plant production of 11-30-0-3s grade ammonium polyphosphate sulfate suspension fertilizer.
TVA has patented and is developing in the pilot plant a process whereby an ll-30-0-3S-grade ammonium polyphosphate sulfate (APPS) suspension that contains about 50% of the total P205as polyphosphate is produced by adding sulfuric acid to a pipe-cross reactor to generate more heat. The additional heat increases the temperature of the melt in the pipe reactor and thus produces more polyphosphate (50% v3. 20% of total P205as compared with the polyphosphate content of 9-32-0 suspension). The equipment used to make the 11-30-0-3sAPPS suspension is similar to that used to make the 9-32-0 suspension except that the pipe-cross reactor is used to allow the introduction of sulfuric acid to the base of the reactor. The APPS process uses the same packed-tower cooler that was used in the 9-32-0 process, which limits the APPS grade to 11-30-0-3s to prevent salting-out in the packing. The APPS suspension process, like the 9-32-0 process, is energy efficient in that no external heat is required to make the product. The added sulfur will be useful not only to provide additional heat to form higher polyphosphate levels in the product but also to provide maintenance dosages of sulfur. The APPS suspension can either be applied directly to the soil or mixed with other nitrogen fluids and potash in preparation of mixed suspensions of various ratios and grades.
The Process The APPS process is being developed by TVA in a 500 lb/h pilot-plant unit. Figure 1is a process flow diagram. Phosphoric and sulfuric acids are fed to opposite inlets of the pipe cross located a t the base of the reactor, and gaseous ammonia is fed to the run of the pipe cross. The phosphoric acid and liquid ammonia are heated in separate heat exchangers by hot APPS liquor from the reactor surge tank. The sulfuric acid is fed at ambient temperature. The APPS melt discharges into a reactor surge tank where water of formulation is added to produce the nominal ll-30-0-3S-grade APPS fluid. The hot fluid then is pumped to the top of a packed-tower evaporative cooler where the fluid is cooled by a countercurrent flow of air. The cooled liquid then is pumped to a clay-mix tank, where sufficient attapulgite clay is added to supply 2% w/w of
clay in the final product. The clay is added to suspend any crystals or impurities that might precipitate during low-temperature or long-term storage. All major items of equipment and piping are made of Type 316 stainless steel; however, the pipe-cross reactor has a 3-ft-long, 16-gauge, Hastelloy C-276 liner installed a t the feed end. Sulfuric Acid Feed System. The sulfuric acid is fed from a 25-gal storage tank with a variable-volume ballcheck-type metering pump to one of the branches of the pipe cross mounted on the bottom of the pipe reactor. The sulfuric acid is fed at ambient temperature. Phosphoric Acid Feed System. Phosphoric acid from a 300-gal storage tank is fed with a variable-volume ballcheck-type metering pump to the acid heater where it is heated with hot APPS liquid from the reactor surge tank. The acid heater is a plate-and-frame type that consists of 14 plates; Viton gaskets are used between the plates. The total heat-transfer area is 9.8 ft2. The overall heat-transfer coefficient calculated for this unit is 38 Btu h-l ft-2 OF-' when the acid is heated to 190 OF by using process liquid at 205 O F . The hot APPS liquid is pumped from the reactor surge tank and flows countercurrent to the flow of acid in the heater a t a rate of about 6 gal/min. Over a period of time, solids accumulate on the APPS side of the acid heater. The solids have been identified as an iron aluminum ammonium pyrophosphate salt. To allow removal of these solids, the piping to the acid heat exchanger is arranged in such a way that the flows can be reversed; that is, the acid flow can be switched to the APPS liquid side and the APPS liquid flow can be switched to the acid side of the heater without interrupting operation. Feeding acid to the APPS liquid side of the heater for about 15 min each 12-h period will remove the solids buildup and help ensure efficient heating of the acid. Ammonia Feed System. Liquid anhydrous ammonia from a trailer is metered with a rotameter before it enters a heat exchanger where it is vaporized and heated to about 150 O F . The heat exchanger is a single-passshell-and-tube unit with a total heat-transfer area of 15.7 ft2. The ammonia passes through the shell side, and the hot APPS fluid from the discharge of the acid heater passes through the tube side. The overall heat-transfer coefficient cal-
600
Ind. Eng. Chem. Prod. Res. Dev.. VoI. 24, No. 4, 1985
TO REACTOR
I
Figure 2. Pilot-plant pipe-cross reactor for production of ammonium polyphosphate sulfate fluids.
culated for this unit starting with anhydrous liquid ammonia a t 33 O F is 40 Btu h-' f t F OF'. Pipe-Cross Reactor. Several 6-ft-long pipe reactors ranging in diameter from 3/a to 2ll2 in. have been tested to determine the effect of throughput on polyphosphate content. The reactor used most often in the pilot plant is 21/2in. in diameter (Figure 2). All of the pipe reactors are mounted vertically. A line is connected to the discharge end of the pipe reactor to transfer hot melt from the pipe to the reactor surge tank. Inverted L-, inverted J-, and inverted U-shaped transfer lines ranging in diameter from 'I2to 2'/, in. have been tested. The transfer line most often used in the TVA pilot plant is in the shape of an inverted-L with a 2-in.-diameter by 35-inAong horizontal section and a l'/,-in.-diameter by 'Il-in.-long vertical section. Two pipe reactors were installed in the pilot plant, and provisions were made to allow switching operation from one pipe to the other during a run without interrupting production. With two pipe reactors in place, when one pipe reactor becomes partially clogged, hot APPS liquid from the discharge of the ammonia vaporizer is pumped through the clogged reactor to remove the scale from the reactor while ammoniation is carried out in the other reactor. In this manner, operation could continue without stoppages due to-scale buildup for an indefinite period of time. Reactor Surge Tank. The melt from the transfer line, usually a t a temperature of ahout 515 "F, is discharged approximately 10 in. below the surface of the APPS liquid in the reactor surge tank (Figure 3). This tank is 16 in. in diameter and 36 in. high, and it is operated at a liquid depth of about 17 in. The level is maintained by an automatic level controller. Retention time in the tank is about 20 min. Mixing is provided by an agitator that turns at 500 rpm. Water is added to dissolve the melt and to obtain liquid of the desired density. A scrubher (5 in. in diameter and 6 in. tall) with a bed of 1-in. Super Intalox saddles is mounted on top of the tank to recover ammonia that might be evolved. Cool recycle liquid from the
.J Figure 3. Ammonium polyphosphate sulfate suspension pilot-plant reactor surge tank.
Figure 4. Ammonium polyphosphate sulfate suspension pilot-plant packed-tower evaporative cooler.
evaporative cooler is sprayed on top of the 6-in. bed of saddles. The temperature in the tank is controlled hy varying the amount of cool liquid returned from the evaporative cooler. Evaporative Cooler. Hot liquid from the reactor surge tank is pumped to a distributor mounted near the top of the evaporative cooler, which is 16 in. in diameter and 15
Ind. Eng. Chem. Prod. Res. Dev., Vol. 24, No. 4, 1985 601
AMMONIUM PHOSPHATE, W T % Figure 5. Solubility at 90 O F of ammonium polyphosphate sulfate fluid fertilizers containing 40-60% of Pz05as polyphosphate.
f t tall (Figure 4). The liquid falls onto a bed of packing in the lower section of the tower; the packing is l1l2in.-diameter polypropylene Pall rings. An exhaust fan located at the vent discharge on top of the cooler pulls air through the bottom of the tower countercurrent to the flow of liquid. The air flowrate is controlled with a damper to maintain a pool temperature of 100-110 O F . A small bed (16 in. in diameter and 20 in. tall) of l-in. Super Intalox saddles is located above the liquid distributor to separate entrained liquid from the exhaust air. The volume of liquid in the reservoir a t the base of the tower is about 5 gal. The level of liquid in this reservoir is controlled by gravity overflow from the unit. Retention time in the reservoir is about 5 min. The cooled liquid in the reservoir a t the base of the tower is pumped to a clay-mix tank. Clay-Mix Tank. The clay-mix tank is 8 in. in diameter and 24 in. in height. The volume of liquid retained at the operating level in this tank is about 5 gal, which is equivalent to a retention time of about 5 min a t a production rate of 500 lb/h. Attapulgite clay is added by an auger-type volumetric feeder to supply 2% w/w of clay in the final product. Fluid is withdrawn from the bottom of the tank by a centrifugal pump with a tip speed of 90 ft/s and is recycled to the top liquid surface to provide mixing and to gel the clay. The material makes an average of 20 passes through the pump before it is sent to storage. Operating Problems and Variables Affecting Polyphosphate Level. Major problems associated with production of APPS suspensions have been (1)clogging of the reactor and transfer line due to buildup of scale and (2) clogging of the packing in the evaporative cooler. The rate of scale formation was significantly higher with a smaller diameter (3/4 in. vs. 2 l l 2 in.) pipe reactor. The
21/2-in.-diameterpipe reactor could be operated for about 6-12 h before it had to be cleaned. With a 3/cin.-diameter pipe reactor, excessive pressure buildup occurred in about ll2-lh. The solids that accumulated inside the pipe reactor are composed predominantly of either monoammonium phosphate or diammonium phosphate and an iron ammonium orthophosphate [ (FeNH4)HP04],with a minor phase of an iron aluminum ammonium pyrophosphate, (Fe,A1)NH4P20,. The iron ammonium orthophosphate is citrate and water'soluble. The iron aluminum ammonium pyrophosphate is citrate and water insoluble. Scale buildup is removed from the pipes by recirculating hot APPS fluid from the reactor surge tank through the pipes for periods of about 30 min to several hours. Clogging of the packed tower only occurred when the grade of the APPS suspension was too concentrated and crystals were present a t temperatures above 90-100 O F . To determine the maximum grade that could be used in the tower, salt-out temperatures of several fluids with various grades and sulfur contents were determined; results (Figure 5 ) indicate that the maximum grade is dependent on the amount of sulfur present as well as the total plant food content. The amount of sulfur present also is directly related to the proportion of polyphosphate that is formed. Earlier studies had shown that APP suspensions that contain between 25% and 40% of the P205as polyphosphate will develop strong gels during storage in hot weather. For this reason, the desired minimum polyphosphate content for APPS suspension was set a t 50% of Pz05. Results from the salt-out tests show that the grade of the APPS suspension probably would have to be limited to about an 11-30-0-3s to prevent crystallization in the tower. If a different cooler without packing were
Ind. Eng. Chem. Prod. Res. Dev., Vol. 24, No. 4, 1985
602
53.4 51.2
X
I
17.9
22.4
I
I
, 14i-i60'F
3
2
4
TOTAL SULFUR I N PRODUCT, WT %
Figure 6. Effect of total sulfur content on polyphosphate content in ammonium polyphosphate sulfate fluid fertilizers.
,
20
"
0
"
"
I
U
"""""""
" '
" " " " " " " '
2 3 SULFUR ADDED AS H2SO6, W T %
1
4
Figure 7. Effect of addition of various proportions of virgin sulfuric acid to the pipe reactor on polyphosphate content of ammonium polyphosphate sulfate fluid fertilizers.
used, the grade could be increased to about 12-32-0. With lower amounts of sulfur, the products would contain less than the desired polyphosphate content of 50% of P205 (Figure 6). The amount of sulfur shown in these figures includes sulfur in the sulfuric acid plus that in the phosphoric acid. The data indicate that increasing the amount of sulfur in the product from less than 1% to about 4% causes the product polyphosphate content to increase from about 25% to about 55-60% of the total P205when phosphoric acid heated to about 145-160 O F is used. Use of unheated phosphoric acid lowered the amount of polyphosphate that was formed by about 7-8 polyphosphate percentage points (from about 50 to 43% of the total P2O5). The amount of virgin sulfuric acid (93% H2S04)actually incorporated in the product and its effect on forming polyphosphate is shown in Figure 7. These data show that to produce a fluid containing about 50% of its P205as polyphosphate about 2.5% w/w of sulfur would have to be added when hot (145-160 O F ) phosphoric acid is used and about 3.5% w/w of sulfur would have to be added when unheated (70 O F ) phosphoric acid is used. The effect of heat input to the process on the product polyphosphate content is shown in Figure 8. The heat input was obtained by calculating the total heat of ammoniation of the phosphoric and sulfuric acids. As would be expected, supplying additional heat to the process by adding sulfuric acid resulted in higher polyphosphate contents in the product. The actual data on heat input show that about 690-780 Btu/lb of P205was supplied by
70)
am
K O 1om 1100 TOTAL HEAT I N P i l T , BTU/LB Pros
1200
1305
Figure 8. Effect of total heat input to the pipe reactor on polyphosphate content in ammonium polyphosphate sulfate fluid fertilizers. Table I. Chemical a n d Physical Properties of Nominal 11-30-0-3s-GradeAmmonium Polyphosphate Sulfate Suspension 11-30-0-3s nominal grade formulation, lb/ton 1111 H3P04, 54% P205 267 NH3 427 H20 HZS04, 93% 156 clay 40 chemical analysis, wt 7' 11 total N 30 total P205 3 total S available P205, % of total Pz06 100 polyphosphate P205,'70of total P20b 50 0.37 N:P20Swt ratio 2 attapulgite clay, wt '70 pH, dilute to 90% H 2 0 6.8 11.8 density, lb/gal viscosity, CP at 80 O F 250 at 0 O F 650 solidification temp, O F -30 salt-out temp, O F 90
ammoniating the phosphoric acid and about 210-510 Btu/lb of P205was supplied by ammoniating the sulfuric acid. Test data show that an increase in polyphosphate content of one polyphosphate percentage point would require about 15 Btu/lb of Pz05.This value was determined by assuming that all of the heat generated by ammoniation of the sulfuric acid was used to condense orthophosphate to polyphosphate and that the molten APP initially contained about 25% of P205as polyphosphate and no free water. This heat input is equivalent to 1.34 lb of 93% sulfuric acid per 100 lb of P205. The throughput of the pipe reactor (based on lb of P206 h-' in.? of internal pipe-reactor cross-sectional area) had little or no effect on the polyphosphate level in the suspension when the pipe-reactor diameter was decreased from 2If2 to 3 / 4 in. (increase in throughput from 34 to 120 lb of P,06 h-l in.-2). Both size pipe reactors gave polyphosphate levels of about 50% of the total Pz05when equivalent amounts of sulfuric acid were fed to the pipes. Composition and Physical Properties of 11-30-0-3s The pertinent chemical and physical properties of the 11-30-0-3s base suspension currently being made in the TVA pilot plant are given in Table I. With a nominal grade of ll-30-0-3S, the suspension should have a pH (diluted to 90% H,O) of 6.6-6.9 and a density of about 11.8
Ind. Eng. Chem. Prod. Res. Dev., Vol. 24, No. 4, 1985 003
Raw Material hP04
54% P2Os 70% &Os NH3 93% H&O, Clay
Assumed Raw Material Costs for Production Delivered Of Price, $/Ton 1 1 - 3 0 - 0 - 3 s 9.5-3P-0 10-34-0 175.50 250.00 180.00 74.00 81.14
97.50
$/Ton Product 104.00
0
0
24.04 6.10
20.77
0 136.00 21.86
0
0
126.39
157.66
1.62s1.62 0 Total 1 2 9 . 0 6
+
Total
$/Unit N &Os 3.15 3.05
3.59
Figure 9. Raw material costa for production of fluid fertilizers.
lb/gal. The polyphosphate level should range from 50 to 55% of the total P205,depending on the concentration and water content of the phosphoric acid used and the proportion of sulfur in the product. The suspension should store for short times at temperatures as low as -25 to -30 O F without solidification. The viscosity is such that the suspension should flow freely at higher temperatures. As is the case with all suspensions, agitation of the APPS suspension at least once a week is recommended to prevent crystals from growing to excessive size and to prevent strong gels from forming. A comparison of the composition of 11-30-0-3s and 932-0 suspensions and a 10-34-0 clear liquid made from wet-process superphosphoric acid shows that 10-340 liquid has the advantage of having a somewhat higher polyphosphate content (60-70% vs. 50-55% of the total Pz05 for 11-30-0-3s APPS suspension and 20-25% of the total P205for 9-32-0 APP suspension). The 11-30-0-3s and 9-32-0 suspensions each contain about 41% total plant food as compared with 44% for the 10-34-0 liquid. The 3% sulfur content of the 11-30-0-3sfluid will give an advantage in areas of the country where the soil is deficient in sulfur. All three produds have low solidification temperatures and can be handled and stored in all areas of the United States. Both the 11-30-0-3sand 9-32-0 suspensions contain solids, but the 10-34-0liquid does not. The lack of solids in the 10-34-0liquid, however, would likely be an advantage only where low rates of application are to be used.
Cost Comparison of APPS A comparison of the cost of the raw materials required to produce ll-30-0-3S, 10-34-0,and 9-32-0 (Figure 9) shows that on a dollar per unit of N P205basis the raw material costs for the 9-32-0APP suspension are the lowest at $3.05, followed closely by the 11-30-0-3s APPS suspension at $3.15. The cost of the raw material of the 10-34-0 APP liquid ($3.59 per unit of N + P205)is more expensive than that for either the 9-32-0 or 11-30-0-3ssuspension. If these products are shipped, assuming equal production costs, the relationship of 10-34-0being more expensive than either of the suspension products remains essentially the same regardless of the distance shipped because the total plant food content (N + P205)of the three produds is essentially the same. The total of the raw material and shipping costs of 11-30-0-3sAPPS suspension averages about lO&/unit
+
N + P205higher than that for the 9-32-0, but the higher polyphosphate content and sulfur content of the 11-30-0-3s APPS suspension should make it a very desirable suspension. Retrofitting the 11-30-0-3s Process into Existing 10-34-0 Plants There are 130-150 pipe-reactor plants in the United States in which 10-34-0 APP liquid fertilizer is produced from wet-process superphosphoric acid. Although the design of most of the plants was based on the TVA process, the equipment used to make 10-34-0liquid fertilizer usually varies somewhat from plant to plant. With minor equipment changes, the APPS process could be retrofitted into an existing 10-34-0 plant. Items of equipment that would have to be installed are an acid heater, a sulfuric acid feed system, and a clay-mixing system. Provisions would have to be made to have a source of merchant-grade acid to feed to the process, and if a separate reactor surge tank were not available, one would have to be installed. Also, to obtain a production rate of 11-30-0-3sequal to that of 10-34-0,larger diameter pipe-cross reactors would have to be installed. Of course, each plant should be evaluated and the equipment tailored for that particular plant. TVA plans to modify the 9-32-0 APP demonstrationscale plant to allow production of 11-30-0-3s APPS suspension. The design production rate of this plant is 20 tons/h of 9-32-0 suspension. The APPS plant is scheduled to become operational in July 1985. Product from the APPS plant will be used in TVA test-demonstration programs in which TVA fertilizers are distributed throughout the United States for evaluation of their agronomic, handling, and storage properties. Patents U.S. Patent 4 377 406 covering the APPS process and the reactor design is on file in the U.S. Patent Office. In accordance with usual TVA policy, nonexclusive licenses will be granted for use of the process. Registry No. S, 7704-34-9; NH3, 7664-41-7. References (1) "New Developments In Fertlllzer Technology: Eleventh Demonstration.'' TVA Bulletin, 1976, No. Y-107. (2) "New Developments In Fertilizer Technology: Twelfth Demonstration." TVA Bulletin, 1978, No. Y-136. (3) Wllbanks, J. A.; Burns, M. R.; Watson, J. R. Farm Chem. 1080, 743(3), 54-5. (4) "New Developments In Fertilizer Technology: Thlrteenth Demonstration." TVA Bulletin, 1980, No. Y-158. (5) "New Developments In Fertlllzer Technology: Fourteenth Demonstration." TVA Bulletin, 1983, No. Y-181. (6) Mann, H. C.; McGIII, K. E.; Jones, T. M. Ind. Eng. Chem. Prod. Res. Dev. 1082, 21, 488-95. (7) "Plant-Scale Production of 9-32-0 Ammonium Polyphosphate Suspension Fertlllzer From Merchant-Grade Phosphoric Acid." TVA Circular, 1983, NO. 2-154.
Received for reuiew December 11, 1984 Accepted May 10, 1985 Presented a t the 188th National Meeting of the American Chemical Society in Philadelphia, PA, August 27-29, 1984.
