THE UNIVERS ITY OF MI CHI GAN COLLEGE OF ENGINEERING Department of Chemical Engineering Final Report SPRAY EVAPORATOR FOR STICKWATER FROM RENDERING OF FISH Lloyd L. Kempe,'Professor Dale E. Briggs, Assistant Professor Collaborator: John L. Oscarson DRDA Project 010549 under contract with: U. S. DEPARTMENT OF COMMERCE NATIONAL MARINE FISHERIES SERVICE FISHERY PRODUCTS TECHNOLOGY LABORATORY CONTRACT NO. N-043-23-71 GLOUCESTER, MASSACHUSETTS administered through: DIVISION OF RESEARCH DEVELOPMENT AND ADMINISTRATION ANN ARBOR October 1973

TABLE OF CONTENTS Page LIST OF TABLES iv LIST OF FIGURES v SUMMARY vii INTRODUCTION1 EQUIPMENT AND OPERATING PROCEDURES Spray Concentrator Air heating system 7 Fluid pumping system 10 Concentrating chamber 12 TEST EQUIPMENT AND MEASUREMENTS 16 Operation of Equipment 17 Start Up and Operating Procedures 17 Shut Down Procedure 18 EXPERIMENTAL RESULTS 19 CONCLUSIONS 40 LITERATURE CITED 41 APPENDIX A. LISTING OF COMPUTER PROGRAM FOR PROCESSING DATA AND SAMPLE CALCULATION 42 APPENDIX B. SUGGESTED DESIGN OF A MODIFIED 10,000-GALLON PER DAY SPRAY CONCENTRATOR 51 iii

LIST OF TABLES Table l:ag e I. Identification and Description of Spray Nozzles 19 II. Summary of Spray Concentrator Evaluation Data with Water as the Test Liquid for Delavan Nozzles WRF40 and WRF45 22 III. Summary of Spray Concentrator Evaluation Data, with Water as tile Test Fluid for Delavan Nozzle WRF60 and Bete Nozzle TF16N 24 IV. Summary of Spray Concentrator Evaluation Data with Water as the Test Fluid for Bete Nozzle TF14FCN 25 V. Summary oft Spray Contcenttrator EIvaluationi Data, w Ltl Water as the Test Fluid t f'or Bete Nozzle B121'C 26 VI. Effect of Two Nozzle Location and Flow Rate oin ]vaporation Rate for a Total Water Flow Rate of 3000 lb/hr Through Nozzles 27 VII. Summary of Spray Concentrator Evaluation Data with Water as the Test Fluid for Bete Nozzle TF20FCN and Delavan Nozzles WRF20, WRF25, and WRF30 28 VIII. Summary of Spray Concentrator Evaluation Data with Water and Corn-Steep Liquor as the Working Fluid for Bete Nozzle B12FC 29 IX. Physical Characteristics of Corn-Steep Liquor 38 iv

LIST OF FIGURES Figure Page 1. Flow diagram. 2 2. Bete Flow Nozzle, Inc. spiral nozzles tested in the spray concentrator. 4 3. Delavan Manufacturing Company centrifugal pressure nozzles tested in the spray concentrator. 5 4. Diagram of spray concentrator for fish stickwater. 6 5 Detail view of gas burner in spray concentrator for fish stickwater. 8 6. Diagram of air heating equipment in spray concentrator for fish stickwater. 9 7. Close-up view of the Blackmer pump and recirculation piping system. 10 8. Diagram of fluid pumping system in spray concentrator for fish stickwater. 11 9. Detailed drawing for the chamber of the fish stickwater concentrator. 13 10. General view of the chamber of the fish stickwater concentrator. 15 11A. Laboratory set-up to evaluate spray characteristics of nozzles used in the spray concentrator. 20 11B. Close-up view of spray from a Bete spiral nozzle. 20 12. Effect of nozzle flow rate for Delavan nozzle WRF60 on the evaporation rate of water in the spray concentrator. 30 1.,'ffect of nozzle flow rate for Bete nozzle TF16N on the evaporation rate of water in the spray concentrator. 31 14. E'ffect of air flow rate and nozzle flow rate for Bete nozzle TF14FCN on the evaporation rate of water in the spray concentrator. 32 v

LIST OF FIGURES (Concluded) Figure Pae.e 15. Effect of air flow rate and nozzle flow rate for Bete nozzle TF14FCN on the evaporation rate of water in the spray conceintrator. A; 16. Effect of air flow rate and nozzle flow rate for Bete nozzle B12FC on the evaporation rate of water in the spray conlceiltrator.;4 17. Effect of nozzle flow rate for Blete nozzle TF120FC.lN on thle evaporation r.ate of water in the spra.y conlcetitr.at(or. 35 18. Eff'ect of air flow rate and n:ozzle flow rate ol. the evaporat io.r rate of' water in the spray concentrator. 36 19. Effect of corn-steep liquor concentration on the evaporation rate of water in the spray concentrator. 37 B-l. Schematic drawing of recommended spray concentrator showing nozzle layout. 53 v.i

SUMMARY The objectives of this work were to study the rate of evaporation from a water spray directed cocurrently into a chamber through which hot combustion gases from a natural gas flame were flowing. This involved measurements of fuel economy and heat and mass balances together with evaluation of this performance for various kinds of spray nozzles considered suitable for use with water suspensions of solids and determination of the ability of the procedure to concentrate diluted corn-steep liquor. For these studies it was necessary to reactivate the cocurrent, spraytype evaporator that had been designed and built for these purposes and which is located on the roof of the George Granger Brown Laboratories of The University of Michigan. Once this was done, the objectives of this study were accomplished. It was found that: (1) The present apparatus evaporated over 550 lb of water per hour using a fuel consumption of about 1,000,000 Btu/hr with an efficiency close to 60%. (2) The Bete-Fog nozzles used in the evaporator produced an adequate spray for evaporation purposes and did not clog in the runs where corn-steep liquor was being concentrated. (5) The presence of corn-steep solids did not materially affect this evaporator operation or the evaporation rate. Nevertheless, such solids would be expected to cause problems if their concentration in the solution being evaporated were allowed to rise much above 30%. (4) The future design of a concentrator based upon these studies should take into consideration the facts that most of the evaporation occurred in the top 3 to 4 ft of the chamber and that no scorching of corn-steep solids was observed under the operating conditions evaluated. vil

INTRODUC TION Sl ickwal,er froml wet; ren(dering of'ish as illustrated in Figure 1 has a very high T3(D. It can no longer be discharged untreated into natural waters. Fortunately this stickwater is really a dilute solution of protein that is quite acceptable as a component of chicken feed which many fish rendering plants produce. Before the dissolved protein can be added to the chicken feed, however, it is necessary to concentrate the solution. This originally contains about 5% protein: it should be concentrated to about 35% before being sprayed into the kiln-type dryer. Concentration can be accomplished in double effect evaporators (R-l), but the equipment is costly to buy and difficult to operate. Submerged combustion and Vincent evaporators (R-l), have also been suggested for this duty, but they are reported to present operational problems. None of these appear to have been used effectively in the Great Lakes area. Our studies of this problem began over five years ago at the suggestion of the then U.S. Bureau of Commercial Fisheries. During the first phase of the work the need for a better stickwater treatment method was documented, the methods of treatment in use were studied and a proposal was made for cocurrent spray evaporation (R-l). The latter evaporation method appeared to offer a number of advantages for small rendering plants. These advantages were discussed in the report for this phase of work (R-l). Next we received sufficient financial support to build a cocurrent, spray evaporator that used hot combustion gases from a gas-fired burner to evaporate water. This allowed us to begin a study of the possible use of such an apparatus for concentration of stickwater, which constituted the second phase of the study. Design, construction, and preliminary operation characteristics of the concentrator were reported (R-2). On the basis of these studies we received further financial support to continue and the present phase of the work was undertaken. The proposal for the present work stated three steps to be accomplished. Briefly these included first, putting the equipment in operating condition by replacing the pump and the air duct with better equipment; second, testing the rate of evaporation, fuel economy, various kinds of spray nozzles and the drop sizes that they produced using water as the fluid; and finally, if the above were accomplished with the funds available, testing the equipment by evaporating distiller's solubles or corn-steep liquor. It was pointed out in the proposal that if these tests were encouraging that then the next phase would involve further funds for testing the equipment on actual fish stickwater. Odor problems are to be expected with fish waste and the tests would be best accomplished at a fish rendering site. These objectives then became the basis for the present study. 1

(STEAM) (W- ) (W-2) (W-3) -< —. ~ KILN TYI DR I ER (W-4) -<-..... (PRESS CAKE):AM) HAMMER MILL FLOOR CENTRIFUGE STORAGE BIN (W-5) FISH OIL OR TRUCK (W-6) STICKWATER [PRODUCT] OR TRUCK DRY FISH MEAL [PRODUCT].........GASEOUS WASTE --— LIQUID WASTE PRODUCT Figure 1. Flow diagram. Alewife rendering pla - us-in the wet rendering -rocess'P- ).

EQUIPMENT AND OPERATING PROCEDURES With these observations in mind we designed, built, and have tested a device that should effectively concentrate fish stickwater discharged from small rendering plants. It should also eliminate or significantly reduce the deficiencies just discussed for other evaporators that also employ the principle of contacting bulk liquids, jet streams, or drops of water with hot combustion products. A number of preliminary experiments were necessary to provide data upon which to design the apparatus. These include (1) testing of numerous atomizing nozzles to determine their spray patterns for water, (2) assembling and testing the fluid storage and pumping system that is now incorporated in the apparatus, and (3) fabricating a small spray tower from sheet iron to test the assembled equipment, less the burner. This small sheet iron unit was discarded after serving its purpose. In order to determine the required dimensions of the concentrating chamber and the size of the gas burner for design purposes, the expected evaporation rates of water from drops were calculated using an iterative procedure. This method predicted that 3.45 lb/min of water would be evaporated from 1.05 gal/min of feed using an inlet temperature of the combustion gas at 900~F and a drop size of 800. Assuming an efficiency of 50% and a feed rate of 1 gal/min, the approximate heat requirement is 1,000,000 Btu/hr. This was the basis for the purchase of a 1,000,000 Btu/hr, gas-fired burner for this installation. While evaluating various nozzles to be used for spraying water droplets into the concentrating chamber, we also kept in mind the problems that will likely develop when spraying stickwater. We anticipate that the stickwater will first be passed through a rotary screen. However small particles, together with burn-on, may tend to clog nozzles of the type that are otherwise satisfactory for water. Tate (R-3) discussed the advantages and disadvantages of alternative drop producing devices in a review article on sprays. The Bete Fog Nozzle, Inc. (R-4) spiral nozzles, the Delavan Manufacturing Company (R-5) centrifugal pressure nozzles and the rotary atomizers all seemed appropriate. Bete and Delavan nozzles were used in the study and are shown in Figures 2 and 3. S iPRAY CONCENTRATOR The spray concentrator that we have assembled and tested is shown schematically in Figure 4. It has three major components, namely, (1) Air Heating System, 3

Figure 2. Bete Flow Nozzle, Inc spiral nozzles tested in the spray concentrator.

DELdVAIJ BRF 25 RF a Figure 3. Delavan Manufacturing Company centrifugal pressure nozzles tested in the spray concentrator, Top view shows the outlet orifice and bottom view shows the inlet orifice.

n1 n n Section AA 8- 2"x 8" Gas Vents -~ Thermocouple U U Partlow Temperature Controller Spray Exit Figure 4. Diagram of spray concentrator for fish stickwater.

(2). Fluid Pumping System, (3) Con-centtrating (Chamber. Air Heating System A 1,000,000-Btu/hr, gas-fired burner with a minimum turn-down ratio of of 40 to 1 is used as the energy source. It was produced by the Industrial Burner Systems, Inc., Detroit, Michigan (R-6). A picture of the burner attached to the spray concentrating chamber through the "T" connection is shown in Figure 5. The flexible hose used for combustion air shown in Figure 5 was replaced by a 6-in. diameter galvinized sheet metal duct after the initial tests. Included with the burner are a 40,000 standard cubic feet per hour (SCFH) turboblower and a cylindrical chamber in which the hot combustion gases are mixed with excess air. This chamber has a length of 3 ft and a diameter of 16 in. Safety devices, that are required by "Factory Mutual Insurance," have been included in both the gas chain and its accompanying control system. Most important among these safety devices is an electrically operated ECLIPSE, "Safety Shut-Off Valve" (R-6) which is linked with a protection control box that shuts down the system upon failure of the flame or of the blower, or upon loss of electrical power. The gas chain and safety control systems are shown schematically in Figure 6. It will be noted that a portion of the air is used for initial combustion and enters through the rear of the burner while the remaining fraction enters tangentially into the cylindrical mixing chamber. This chamber is 3 ft long, 16 in. in diameter is covered with a 2-in. layer of insulation. Dampers are present in both lines to regulate air flows. Diluted combustion gases pass from the mixing chamber to a "T" connection between the concentrating chamber and the burner. Here the hot gases can either be vented to the atmosphere or diverted into the chamber by opening or closing the flap-valve at the straight end of the "T." This was installed as a safety device. The "T" is kept open until the burner is operating satisfactorily at start up, then the valve is closed. A number of component parts are associated with the gas supply for the burner. From upstream to downstream these components are a Nordstrom, manually operated gas cock, a pilot gas cock, an Eclipse Model 204 T-3 electrically operated main-gas safety shutoff valve, and a Partlow indicating temperature controller. The desired temperature at the exit of the cones is monitored by a vapor expansion thermometer. The gas flow is correspondingly adjusted by a controller. There is also an automatic solenoid valve in the pilot gas line. A "Unified Control Panel," made by Protection Controls, Inc., Skokie, 7

Figure >. Detail view of gas burner in spray concentrator for fish stickwater. 8

Solenoid,To Control Valve,' Panel Pi Pilot Stop Cock -Gas Insulated KA\/i vin ri Flap UnneCin ie IA IIY Chamber BURNER Dampers/ Hot By Pass Air Gases uOuter Cone oDo lnner o o ooCone o o o Hot Gases H Hot Gases Concentrati ng Chamber Vent Openings Figure 6. Diagram of air heating equipment in spray concentrator for fish stickwater. Combustion Air 6 Inch Diameter'Galvanized Sheet Metal Duct kir Sir t Turbo Air Blower

Illinois, controls the ignition and maintenance of the flame, Fa'lure of the blower or of the flame results in automatic closure of the pilot gas valve and of the main-gas safety shutoff valvee A Dresser Industries, Inc, Model No 1 5M/TC Rotary Rootsmeter positive displacement gas meter was installed in the gas line to measure the gas flow rate. The manufacturer's calibration indicated a masximum error of 0,68%, Fluid Pumping System The fluid to be concentrated is retained in a 55-gal drum shown in Figure 7, A Blackmer rotary pump model SNP 1-1/4 and its accompanying 3-hp Figure 7. Close-up view of the Blackmer pump and recirculation piping system. electric motor are positioned below the drum, Fluid is drawn from the drum or the concentrating charber as shown in Figure 8 and is pumped through a 3/4-in^ steel pipe and a flexible hose to a 2-ft section of 3/8 in0 stainless 10

Hot Gases \\\ Concentric 45~ Cones 0 0 Gases 0 Spray Liquid t Concent rating Chamber (Sectioned) Rotameters Figure 8. Diagram of fluid pumping system in spray concentrator for fish stickwater.

steel nozzle in the center of the cone, directly above the spray chamber. A flange welded to the pipe is attached to a companion flange connected to the point of attachment of the cones to the top of the chamber. Two additional spray nozzle locations were added after initial testing. The locations, shown in Figure 9, were selected to give greater spray coverage within the chamber. The spray from the nozzles impinges the chamber walls approximately 4 ft below the nozzle. When the lowest nozzle location was used, the spray from the nozzle was directed upward. Calibrated rotameters were installed to measure the liquid flow rates through the nozzles. In most of the runs only the uppermost nozzle location was used. In a few instances the uppermost nozzle location was used in conjunction with one of the lower locations. Valves are located at appropriate locations to allow the operator to regulate the liquid flow rate to one or more nozzles and to adjust the amount of recycle compared to fresh liquid feed. The liquid flow rate through the nozzles influences the drop size. At low flow rates the drops are large; they become smaller as the flow rate increases. Smaller drops are preferred because of the large total surface area available for evaporation. Evaporation occurs as the sprayed drops fall through the length of the chamber. Approximately 20% of the liquid is evaporated. Concentrated fluid is collected in the bottom of the concentrating chamber and is recycled as desired. A second feed tank was added for evaporating corn-steep liquor on a once through basis. The tank which was approximately 80 gal in volume was connected in parallel to the existing feed tank. It permitted a constant premixed feed concentration to be fed to the evaporator during the period of a test run. During such a run all the concentrated liquid was collected in the bottom of the concentrating chamber and not recycled. Concentrating Chamber The detailed drawing shown in Figure 9 was used for fabricating the spray concentrator. The chamber was constructed from 3/16 in. steel. It stands 18 ft tall, has a diameter of 5 ft 4 in., and weighs approximately 3000 lb. Basically, it consists of a concentrating cylinder covered with two 45~ cones. The cylinder itself is 12 ft high. Two, 8-in. exhaust ports are located near the bottom of the cylinder. They are positioned opposite each other with centers 2 ft above the level at which the conical floor of the chamber joins the cylinder and directly above one of the exhaust ports. The chamber stands on four 1-ft legs, each equipped with 8-in. square pads; its conical bottom 12

Gas Inlet Spray Chamber SteeSpy Nzle Detail Stee-I Spray Nozzle 51-4" 12 1 2' / I 20" Covered,b -......L_.:= Manhole B) - i [.T SI tuD tb~ _ | \ 4 Legs and 8" Square 6 16' - Pads at 90 Intervals Figure 9. Detailed drawing for the chamber of the fish stickwater concentrator. 13

drops 4 in. from edge to center to facilitate drainage. Atop the cylinder are the two concentric, 45~ cones (Figure 6). Hot combustion gases are forced into the 2.8-in. annulus between the two cones. Six inches above the base of the interior cone are eight symmetrically spaced slots each of which are 2 in. high and 8 in. wide. These slots direct hot combustion gases out of the annulus perpendicularly into the rain of descending water drops from the nozzle. This concentrating chamber was fabricated by the Plymouth Tank Company of Plymouth, Michigan. Since the chamber weighs about 3,000 lb a large crane was needed to lift it to the roof of the G. G. Brown Laboratory where it is now located. All of the auxiliary services are located inside the building but the concentrating tank and the burner are outside, exposed to the weather. This was necessary because of the rather large amount of both heat and exhaust vapors involved. The outdoor location however does restrict testing of the equipment to about six months of the year. For other reasons as well, our tests were carried out during the summer months although the tank itself was actually installed in the middle of winter. A picture of the concentrating chamber in position on the roof of the G. G. Brown Laboratory is shown in Figure 10. I )I

Figure 10. General view of the chamber of the fish stickwater concentrator. jr5 ~.^

TEST EQUIPMENT AND MEASUREMENTS There are three principal independent variables to be measured and controlled. They are the volume of air flow, the temperature of the gases in the cone of the evaporator and the rate at which fluid sprays from the nozzle (or nozzles). In addition, the fraction of the air which by-passes the burner and is added to the mixing chamber can also be adjusted. This affects the burner temperature for a given cone temperature. It was also necessary to measure the volume of water evaporated per hour, temperatures and humidities of the inlet and outlet gases, the feed fluid temperature and the product temperature. The air flow rate was adjusted by setting the air dampers shown in Figure 6 to the positions desired. Commercially manufactured high-temperature, chromel-alumel thermocouples were screwed into fittings previously welded into the apparatus. Their locations are shown in Figure 4. They were used to measure gas temperatures at any time during a run starting with combustion products from the mixing chamber, then in the annulus, at various points in the chamber and in the exhaust. The liquid feed and product temperatures were also measured with thermocouples. Because of the presence of the spray within the chamber, the wet-bulb temperature rather than the dry-bulb temperature was measured at most locations. It is quite likely that the gas temperature measurement in the cone was influenced by the fine spray which exists behind the nozzle. Dry-bulb and wet-bulb temperature readings of the inlet and exhaust air were measured by mercury-in-glass thermometers. The humidities of the inlet and exhaust air were determined from the readings. The amount of water evaporated during the period of a run was determined by noting the amount of fluid added during the run to maintain the same liquid levels in the concentrating chamber and the feed tank. The measurements could be made with a maximum error of 1% or less. Air flow rates were computed from absolute humidity values and the amount of water evaporated. Tnlet and exhaust air flow rate measurements were also made with a vane-type anenometer and a velometer. Since the velocity profile varie(d across the face of the inlet and exhaust ducts, several rea(diings,h(d l,o be made to provide an integrated average value. The air'low ra-es ornpiltfc( from the change in hulmidity and the water evaporate(l -ag-reel with Ut:i 1 t,(:r,,tve' values. Because they were more reproducible and straightforward(, the,air flow rates tabulated in the report were evaluated from humidity changes. 16

Tre spray rates were (cetermined( from calibrate( rotameter readings. Rates of gas consumption were measured with a calibrated Dressier Rotary Rootsmeter positive displacement meter. The meter readings were corrected for gas temperature and pressure. Errors in gas flow rates were less than 1%. The amount of heat absorbed by the evaporator was determined from the feed and product temperatures and the amount of water evaporated. After the initial run, a demister was fitted to the exhaust port from the chamber; the other port was sealed. The demister consists of a 3-ft long cylinder 12 in. in diameter and closed on one end. Outlet gases enter this demister through an 8-in. pipe that protrudes about 6 in. into the chamber. This was necessary in order to exclude water that runs down the inside wall from mixing with the exit gases. Once inside the demister, the gases exit upwards through a 6-in. hole. Water that is removed by the demister drains from a 2-in. hole in the bottom of the cylinder. The amount of water thus removed was negligible compared to the amount evaporated but its volume was nevertheless included in the calculations. OPERATION OF EQUIPMENT In order to successfully fulfill the requirements for a good fish-stickwater concentrator, the equipment must be easy and quick to start and stop as well as easy to use. It should be inexpensive to purchase, install, and operate. With these thoughts in mind, a detailed description of the steps required to start and shut down the spray concentrator are given below. START UP AND OPERATING PROCEDURES 1. Pour fluid to be concentrated into the 55-gal fluid reservoir (Figure 8) until it is about two-thirds full. Also pour some of the same fluid into the concentrating chamber until the fluid level gage at the bottom of the chamber shows at about the halfway mark (Figure 4). These fluid levels should be approximately maintained during a run; at the end of a run it is particularly important that both levels be exactly reestablished at their original heights in order that precise measurements of the amount of water evaporated can be made. 2. Start the air blower from the control panel 3. Start the fluid pump and adjust the liquid flow rate using the gate valve in the by-pass line around the pump (Figure 8). Usually, only a fraction of the water sprayed evaporates. The excess water collects in the bottom of the evaporator from whence it is pumped back to the spray nozzle. 17

4. After the blower operates for 5 min, open the by-pass flap-valve on the "T" connection to the chamber. 5. Open the plug valve in the main gas line and also open the pilot stop cock (Figure 6). 6. Open and adjust dampers in the inlet air lines (Figure 6). 7. Set the temperature control at "minimum fire." 8. Start the pilot gas flame from the control panel. A red light indicates ignition has occurred. 9. Ignite the main gas burner by manually opening the Eclipse safety shut-off valve. 10. Adjust the temperature controller and air dampers in order to provide the desired conditions for the run (Figure 6). 11. Close the by-pass flap on the "T" connection in the pipe carrying hot combustion gasses from the burner to the concentrator (Figure 6). By following this procedure, steady state can be achieved in about 30 min At steady state, the gas temperatures in the burner exhaust, in the cone, and in the exit gases from the evaporator remain essentially constant. SHUT DOWN PROCEDURE The spray concentrator is shut down by effecting the following steps in order: 1. Turn off the fluid pump. 2. Stop the air blower from the control panel. This automatically shuts off the gas burner. 3. Close the main gas stop cock and also the pilot stop cock. 4. Completely drain fluid from the pumping tank, the concentrating chamber and from all pipes. 18

EXPERIMENTAL RESULTS The nozzles used in the investigation are shown in Figures 2 and 3. They w(re&'ill checked in the laboratory to evaluate spray characteristics at differ(ent.['low rntes as illustrated in Figure 11. The nozzle descriptions are given.i r- T'able 1.. TABLE I IDENTIFICATION AND DESCRIPTION OF SPRAY NOZZLES Relative Drop Desipn. ed Cone Nozzle I Size at Spray I,'low KRa.ite,,, Angle, Number / Operating Cone lb water/hr C deg Conditions Delavan Nozzles WRF20 1000 Fine Hollow 65 WRF25 1250 Fine Hollow 70 WRF30 1500 Fine Hollow 70 WRF40 2000 Medium Hollow 70 WRF60 3000 Medium Hollow 70 Bete Nozzles B12FC 3000 Fine Full 120 TF14FCN 4050 Fine Full 90 TF16N 5050 Medium Hollow 50 TF20FCN 7250 Large Full 90 *The designed flow rate is the flow rate of water through the nozzle at a pressure drop across the nozzle of 40 psi. N.-zzles:ire designed to operate over a limited range of flow rates and use -lhe pressure dJeAt-rence across the nozzle to promote drop formation. At low -'low ra-te-s:ind small pressure differences the mean drop size is relatively l:irge:nd the drop size becomes progressively smaller as the flow rate increases. At high flow rates the energy required to overcome the pressure differences across the nozzle exceeds the advantage of smaller drops. The rated flow rates in Table I are for a pressure difference of 40 psi. Under the operating condi 19

Figure 11A Laboratory set-up to evaluate spray characteristics of nozzles used in the spray concentrator. Figure llBo Close-up view of spray from a Bete spiral nozzle. 20

tions, the larger nozzles produced medium or large drops as the flow rate was limited by the pump capacity.. The er? — imental work on the spray concentrator was conducted during the summers of 1971 and 1972. After construction of the equipment and initial checkout, ten runs were made in the summer of 1971 to evaluate the spray concentrator. Water was used as the working fluid. The data are tabulated in Table II. During th': first four runs considerable information was obtained concerning the operation of the evaporator and measurement of operating conditions. At first the exit wet- and dry-bulb temperatures were measured with a sling psychrometer inserted into the exhaust port at the side and near the bottom of the evaporator through which the exit air passed. The wet- and dry-bulb temperatures were approximately equal. However when the sling psychrometer was placed in the path of the exit gases, but outside of the duct, the dry-bulb temperature was 20~ to 40~F higher than the wet-bulb temperature. Inside the duct, entrained water impinging on the dry-bulb thermometer caused the dry-bulb thermometer to behave as a wet-bulb thermometer. Before Run 5 the expansion thermometer located in the cone was withdrawn a few inches. At the new location, the cone temperature was roughly 300~F higher than at the previous location, under similar operating conditions. Water sprayV striking the thermometer apparently caused the lower temperature. The cone temperatures listed for Runs 1-4 are therefore low by approximately 300~F. When the inside of the evaporator was inspected at the end of Run 7, it was found that the spray nozzle insert was missing. Since the operating conditions and results for Runs 2-7 were rather consistent, the insert apparently came out during the first run. A calibration of the nozzle withcut insert was made to determine water flow rate as a function of pressure. Even though the spray distribution and drop size were not ideal, the results for Runs 2-7 were the best in ter'lms of evaporator efficiency and total evaporation rate indicating that the evaporator could be operated at higher flow rates. As can be seen from Table II, evaporator efficiencies of over..0%O can be achieved, at cone temperatures of 800~F and water flow rates of 3200 lb/hr. At these conditions, approximately 17% of the water is evaporated per pass, resulting in an evaporation rate of about 560 lb/hr. The burner temperature is nearly 1400~F. At lower water flow rates the evaporator efficiency is considerably less. Several equipment modifications were made in the spring of 1973 to improve operations. These included: 1. The replacement of the flexible air duct with a 6-inch diameter galvanized sheet metal duct. 21

TABLE II SUMMARY OF SPRAY CONCENTRATOR EVALUATION DATA WITH WATER AS THE TEST LIQUID FOR DELAVAN NOZZLES WRF4O AND WRF45 Run Number 1 2 3 4 5 6 7 8 9 Nozzle Number WRF40b WRF40b WRF40b WRF40b WRF40Ob WRF4Ob WRF40b WRF45 WRF40C W Nozzle Pressure, psig 19 20 20 20 20 20 20 22 22 Inlet Air Dry-bulb temperature, ~F 66 82 91 82 84 84 85 83 84 Wet-bulb temperature, ~F 62 76 78 75 67 65 67 67 67 Humidity, lb water/lb air 0.010 0.017 0.018 0.012 0.010 0.009 0.010 0.011 0.011 C Outlet Air Dry-bulb temperature, ~F 180 200 202 202 184 187 200 300 256 Wet-bulb temperature, ~F 154 164 164 162 161 161 165 159 157 Humidity, lb water/lb air 0.220 0.310 0.310 0.500 0.290 0.278 0.310 0.230 0.280 C Cone Temperature, ~F 470 583 590 573 880 858 805 815 779 Burner Temperature, ~F 1286 1423 1433 1416 1486d 1300 1390 1325 1543 Energy Input, Btu/hr 970,000 1,050,000 1,030,000 1,055,000 1,050,000 1,050,000 1,050,000 1,050,000 1,030,000 l,05C Evaporation Rate, lb/hr 402 536 530 547 510 519 557 3355 392 Air Flow Rate, SCFH 50,200 28,200 27,800 30,900 28,500 29,800 29,000 26,100 29,700 28 Heat Absorbed, Btu/hr 449,000 600,000 592,000 611,000 570,000 579,000 623,000 375,000 438,000 572 Efficiency, % 46 60 57 59 55 56 60 36 42 Nozzle Flow Rate, lb/hr 1,350 3,200 3,200 3,200 3,200 3,200 3,200 1,300 5,420 1 Fraction Evaporated/Pass 0.500 0.162 0.166 0.170 0.160 0.161 0.174 0.256 0.114 C aBased on water evaporated and humidity change. bNozzle 40 without insert. CModified with bored out insert. dThermocouple burned out during run. 10 TRF45 20 90 69 ).010 256 155 ).250 810 1525 ),000 531 3, 000? 000 36 L, 580 ).209

2. The installation of a Dresser gas meter. 3. The installation of rotameters for nozzle flow rates. 4. The installation of a new fluid pumping system. These changes were accomplished to eliminate deficiencies encountered while operating the previous summer. During the summer of 1972 forty runs were made with eight different nozzles. Thirty-three runs were made with water as the working fluid and seven were made with diluted corn-steep liquor. The corn-steep liquor concentrate was obtained from CPC International, Argo, Illinois. The data are tabulated in Tables III-VIII and are plotted in Figures 12-19. From the data taken it has been found that the evaporation rate increases with increased: 1. Feed flow rate through nozzle because of smaller average drop size and greater number of drops. 2. Air flow rate. 3. Air temperature. 4. Sprayed liquid temperature. The first two conclusions can be seen in Figures 14, 15, and 16 for nozzles TF14FCN and B12FC. For a given air flow rate and temperature, the evaporation rate increases with the flow through the nozzle because of smaller and mDre drops until the air becomes nearly saturated with water at the exit conditions. Increasing the air flow rate and air temperature increases the water capacity of the exit air for other conditions fixedo The upper limit on inlet air temperature is the temperature which would cause scorching of the solids in the evaporating drops or in the liquid adhering to the internal surface of the spray concentrator. Since the vapor pressure of water increases with temperature, there is an advantage in having the sprayed liquid at as high a temperature as possible. This is accomplished when the flow rate through the nozzle exceeds the evaporation rate and the recycled fluid becomes hotter than the fresh feed. The nozzles which produced the largest drops at the operating conditions gave the lowest evaporation rates. This can be seen when the results for nozzles WRF60 and TFl6N in Figures 12 and 13 are compared with other data. All the nozzles evaluated were capable of evaporating at least 400 lb/hr of water at an air flow rate of 32,000 SCFH and a heat input of 1,000,000 Btu/hr. In most of the runs, the water put into the bottom of the spray concentrator initially was heated by spraying and recycling until the temperature was nearly constant before experimental data were taken. In a few runs only fresh feed was sprayed and the water evaporated collected in the spray

TABLE III SUMMARY OF SPRAY CONCENTRATOR EVALUATION DATA WITH WATER AS THE TEST FLUID FOR DELAVAN NOZZLE WRF60 AND BETE NOZZLE TF16N Run Number 11 12 13 14 15 Nozzle Number WRF60 WRF60 WRF60 WRF60 TF16N TF1 Liquid Spray Rate, lb/hr 3000 3000 3500 2500 3000 35 Inlet Air Dry-bulb temperature, ~F 69 67 84 79 56 Wet-bulb temperature, ~F 57 57 71 72 52 Humidity, lb water/lb air 0.0072 0.0075 0.0138 0.0159 0.0075 0.00 Outlet Air Dry-bulb temperature, ~F 190 187 181 210 224 2 Wet-bulb temperature, OF 15158589 9 159 157 1 Humidity, lb water/lb air 0.2631 0.2655 0.2805 0.2530 0.2442 0.25 Fresh Water Temperature, ~F 68 67 68 74 74 Sprayed Water Temperature, ~F 153 154 155 153 148 1 Burner Temperature, ~F 1321 1318 1332 1332 1312 13 Cone Temperature, ~F 776 772 769 798 781 7 Gas Flow Rate, SCFH 907.1 864.4 912.7 946.9 938 3 943 Energy Input, Btu/hr 934,300 89 00 940,000 975,300 966,400 971,5 Evaporation Rate, lb/hr 342.8 348.3 374.9 295.2 300.1 310 Air Flow Rate, SCFH 22,970 22,820 23,940 22,670 22,610 22,1 Heat Absorbed, Btu/hr 374,700 381,100 410,000 320,800 326,100 338,4 Efficiency, % 40.2 42.8 43.6 32.9 33.7 34 Fraction Evaporated/Pass.114.116.107.118.100.0 16 6N 00 59 51 163.07 57 44 72 50 09'69.2 00.8 40 00.8 89

TABLE IV SUMMARY OF SPRAY CONCENTRATOR EVALUATION DATA WITH WATER AS THE TEST FLUID FOR BETE NOZZLE TF14FCN Run Number 17 18 19 20 21 22 23 39 Nozzle Number TF14FCN TF14FCN TF14FCN TF14FCN TF14FCN TF14FCN TF14FCN TF14FCN TF1l Liquid Spray Rate, lb/hr 2500 3000 3335 2500 3000 3000 2500 1500 Inlet Air Dry-bulb temperature, ~F 73 77 80 74 77 73 88 75 Wet-bulb temperature, ~F 64 65 65 56 59 58 73 6 Humidity, lb water/lb air 0.0107 0.0109 0.0102 0.0059 0.0070 0.0068 0.0147 0.0096 O.C Outlet Air Dry-bulb temperature, ~F 181 173 170 181 177 176 203 344 Wet-bulb temperature, ~F 160 159 159 160 152 156 156 152 Humidity, lb water/lb air 0.2943 0.2872 0.2836 0.2885 0.2223 0.2528 0.2467 0.1750 0. Fresh Water Temperature, oF 72 75 77 77 77 74 78 73 Sprayed Water Temperature, ~F 155 154 153 155 147 150 152 142 Burner Temperature, ~F 1322 1319 1317 1319 1072 1144 110 1069 Cone Temperature, ~F 757 733 714 762 642 642 676 705 Gas Flow Rate, SCFH 874.0 925.5 925.2 910.7 865.5 901.6 863.0 838.5 8 Energy Input, Btu/hr 900,200 953,500 952,900 938,100 891,500 926,600 888,900 963,700 878, Evaporation Rate, lb/hr 353.7 363.3 358.1 565.5 423.4 597.2 409.6 263.4 Air Flow Rate, SCFH 1,240 22,540 22,480 21,790 31,850 26,630 29,180 28,570 27, Heat Absorbed, Btu/hr 385,500 394,700 388,400 394,300 457,900 431,500 l43,300 285,90 72, Efficiency, % 42.8 41.4 40.8 42.1 51.4 46.5 49-9 33.1 Fraction Evaporated/Pass.142.121.107.145.141.132.164.182 ~~~~~~~~~~~~~~~~~~~32.16.18 40 +FCN _000 71 64 )183 224 154?187 73 146 L094 610 53.2 800 50.7 160 800 2.4 160

TABLE V SUMMARY OF SPRAY CONCENTRATOR EVALUATION DATA WITH WATER AS THE TEST FLUID FOR BETE NOZZLE B12FC Run Number 24 25 26 27 28 41 Nozzle Number B12FC B12FC B12FC B12FC B12FC B12FC Liquid Spray Rate, lb/hr 3000 2500 2000 3000 1000 2000 Inlet Air Dry-bulb temperature, F 84 86 86 76 78 75 Wet-bulb temperature, ~F75 75 73 72 72 69 Humidity, lb water/lb air 0.0154 0.0151 0.0150 0.0163 0.0157 0.0143 Outlet Air Dry-bulb temperature, ~F 159 166 201 158 268 196 Wet-bulb temperature, F 153 154 154 156 159 154 Humidity, lb water/lb air 0.2356 0.2352 0.2268 0.2552 0.2137 0.2259 Inlet Water Temperature, ~F 80 80 82 80 80 74 Outlet Water Temperature, ~F 149 148 148 149 149 136 Burner Temperature, ~F 1093 1096 1103 1133 1090 1112 Cone Temperature, ~F 661 665 680 657 699 660 Gas Flow Rate, SCFH 880.8 887.7 869.0 90355 874.3 863.0 Energy Input, Btu/hr 907,300 914,300 895,000 930,600 900,500 888,800 Evaporation Rate, lb/hr 449.1 432.7 400.6 421.0 348.8 555.2 Air Flow Rate, SCFH 3355,260 32,10 31,580 29,00 30,090 28,460 Heat Absorbed, Btu/hr 484,600 467,100 431,600 454,6 76600 876,600 Efficiency, 54.5 51.0 48.3 48.8 50.6.4 Fraction Evaporated/Pass.150.173.200.140.549.178

TABLE VI EFFECT OF TWO NOZZLE LOCATION AND FLOW RATE ON EVAPORATION RATE FORA TOTAL WATER FLOW RATE OF 3000 lb/hr THROUGH NOZZLES Run Number 29 30 31 24 Upper Nozzle Number B12FC B12FC B12FC B12FC Lower Nozzle Number TF14FCN TF14FCN TF14FCN Lower Nozzle Direction Upward Downward Downward Upper Nozzle Flow Rate, lb/hr 2500 2500 2000 3000 Lower Nozzle Flow Rate, lb/hr 500 500 1000 Inlet Air Dry-bulb temperature, ~F 85 84 87 84 Wet-bulb temperature, ~F 74 70 70 73 Humidity, lb water/lb air 0.0163 0.0216 0.0124 0.0154 Outlet Air Dry-bulb temperature, ~F 165 164 176 159 Wet-bulb temperature, ~F 154 152 152 155 Humidity, lb water/lb air 0.2557 0.2270 0.2217 0.2556 Fresh Water Temperature, ~F 81 82 82 80 Sprayed Water Temperature, ~F 149 148 148 149 Burner Temperature, ~F 1096 1092 1095 1093 Cone Temperature 666 655 658 661 Gas Flow Rate, SCFH 862.0 857.3 851.4 880.8 Energy Input, Btu/hr 887,900 883,000 876,900 907,300 Evaporation Rate, lb/hr 431.3 436.7 414.6 449.1 Air Flow Rate, SCFH 32,220 33,050 32,390 33,260 Hcat Absorbed, Btu/hr 465,100 470,200 446,400 484,600 Efficiency, % 52.3 53.2 50.9 54.5 Fraction Evaporated/Pass.144.146.138.150

TABLE VII SUMMARY OF SPRAY CONCENTRATOR EVALUATION DATA WITH WATER AS THE TEST FLUID FOR BETE NOZZLE TF20FCN AND DELAVAN NOZZLES WRF20, WRF25, AND WRF30 Run Number 32 33 34 35 36 37 Nozzle Number TF20FCN TF20FCN WRF30 WRF20 WRF25 WRF25 WRF2 Liquid Spray Rate, lb/hr 3900 3000 1500 1000 1400 500 100 Inlet Air Dry-bulb temperature, ~F 62 68 70 73 74 72 7 Wet-bulb temperature, ~F 59 60 61 58 59 59 Humidity, lb water/lb air 0.0099 0.0092 0.0093 0.0071 0.0074 0.0076 0.006 Outlet Air Dry-bulb temperature, ~F 189 247 210 256 200 447 29 ru Wet-bulb temperature, ~F 151 152 152 154 15 154 15 Humidity, lb water/lb air 0.2066 0.2002 0.2114 0.2083 0.2170 0.1560 O.183 Fresh Water Temperature, ~F 80 78 7 6 76 74 7 Sprayed Water Temperature, ~F 147 149 136 135 144 126 1 Burner Temperature, ~F 1072 1080 1084 1091 1087 1084 108 Cone Temperature 699 706 721 718 681 729 7 Gas Flow Rate, SCFH 883.8 843.8 876.5 856.0 859-3 825.9 8533 Energy Input, Btu/hr 910,300 869,100 902,500 881,700 885,100 850,600 858,90 Evaporation Rate, lb/hr 414.9 380.4 380.0 352.6 39353 182.7 288. Air Flow Rate, SCFH 34,550 32,810 31,250 29,320 30,770 24,140 28,24 Heat Absorbed, Btu/hr 447,300 411,100 411,400 382,000 425,900 198,500 31,,30 Efficiency, % 49.1 47.3 45.6 42.8 48.2 23.2 36. Fraction Evaporated/Pass.106.127.254.353.281.362.17. ~ ~~~~~~~~ ~ ~~~~~~~~~~~~~~~.6 ~..,.7 )8 )50 DO 72 >7.6 )8 52 >9'4'9.3'0 9 )0 9 )O 4 8

TABLE VIII SUMMARY OF SPRAY CONCENTRATOR EVALUATION DATA WITH WATER AND CORN-STEEP LIQUOR AS THE WORKING FLUID FOR BETE NOZZLE B12FC Run Number 42 43 44 45 46 47 48 49 50 Liquid 5%CSL 4.5%CSL 6. 1CSL 10%CSL 10.4%CSL 20%CSL 24.3%CSL Water Water Nozzle Number B12FC B12FC B12FC B12FC B12FC B12FC B12FC B12FC B12FC Liquid Spray Rate, lb/hr 1000 2000 2000 2000 2000 2000 2000 1000 2000 Type Run Once-thru Once-thru Once-thru Once-thru Recycle Once-thru Recycle Once-thru Once-thru Inlet Air Dry-bulb temperature, ~F 86 85 85 81 82 84 84 63 61 Wet-bulb temperature, ~F 76 71 74 68 68 72 71 62 59 Humidity, lb water/lb air 0.0173 0.0136 0.0163 0.0123 0.0118 0.0147 0.0139 0.0121 0.0102 Outlet Air Dry-bulb temperature, ~F 407 174 180 175 173 176 177 370 163 Wet-bulb temperature, ~F 154 147 150 146 152 146 148 147 139 Humidity, lb water/lb air 0.1672 0.1821 0.2064 0.1769 0.2217 0.1752 0.1928 0.1541 0.1354 Inlet Fluid Temperature, ~F 85 91 120 83 136 93 129 63 65 Outlet Water Temperature, ~F 145 131 148 136 145 144 146 122 121 Burner Temperature, ~F 1070 1036 1049 1041 1061 1052 1045 1045 1016 Cone Temperature 706 56 588 502 558 595 573 630 590 Gas Flow Rate, SCFH 823.9 808.0 837.5 832.9 834.3 845.4 821.1 821.4 830.4 Energy Input, Btu/hr 853,800 832,200 862,700 857,900 859,400 870,700 845,700 846,100 855,300 Evaporation Rate, lb/hr 247.7 309.4 364.6 267.53 459.3 304.4 366.9 155.4 255.6 Air Flow Rate, SCFH 30,170 31,460 32,192 28,9350 34,980 32,970 34,070 22,810 36,460 Heat Absorbed, Btu/hr 266,100 329,700 378,400 286,800 469,900 323,600 377,200 169,900 279,200 Efficiency, % 51.2 39.6 43.9 33.2 54.7 37.2 44.6 20.1 32.1 Fraction Evaporated/Pass.248.154.183.133.229.152.184.155.128

500 03 m -i -J I z 0 0 a4 w 400 300 i iI I Average Conditions Gas Flowrate Air Flowrate Burner Temperature Cone Temperature 908 scfh 23100 scfh 1326~F 779 ~F Nozzle No. WRF 60 Runs 11, 12, 138 14-Water 200 100 I r I II 0 ( I I I I I., I 6. A% j~ _k,I JI 6 L — Al %.4 % a 10%, 10-& jft~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - - - - - i~~~~~~~~~~~~~~~~~~ I J 5UU 1000 1500 2000 2500 3000 3500 NOZZLE FLOWRATE - LBS./HR. Figure 12. Effect of nozzle flow rate for Delavan nozzle WJF6c on the evaporation rste of water in the spray concentrator.

500 Nozzle No. TF 16 N Runs 15 a 16-Water Averoge Conditions;a I.U l: 0 Ict:0'0..>.0. 400 300k Gas Flowrate Air Flowrate Burner Temperature Cone Temperoture I 0 941 scfh 22370 scfh 1310~F 775 ~F 0 200 lo00 n\ I I I I I I I u -I - 0 500 1000 1500 2000 2500 3000 3500 NOZZLE FLOWRATE- LBS./HR. Figure 13. Effect of nozzle flow rate for Bete nozzle TF16N on the evaporation rate of water in the spray concentrator.

500 I: C, m -J I w Lcr d: cr 0 a<w Ll. 400 300 )L m Gas Flowrate Burner Temperature Cone Temperature Nozzle No. TF 14 FCN Runs 17-23,- 39 40-Water 884 scfh 1090- 1320~F 650- 750~F 6 —— b-~~~~r' ~_ - wowas Approximate Air Flowrate Average Conditions 32,000 scfh - A - 28,000scfh-0 -o 22,000 scfh - 0,..m 200,ra IOC =,,. I I ~ I I I.I 0 500 1000 1500 2000 2500 3000 3500 3500 NOZZLE FLOWRATE - LBS./HR. Figure 14. Effect of air flow rate and nozzle flow rate for Bete nozzle TF14FCN on the evaporation rate of water in the spray concentrator.

500 Nozzle No. TF14 FCN Runs 17-23, 39 840 - Water Average Conditions I cri -J i Z w Fz C aQ Q0 0 400k Gas Flowrate Burner Temperature Cone Temperature 884 scfh 1090- 1320~F 650- 750~F 0 V 3001 Nozzle Flowrates I bs./hr. V 1500 * 2000 0 2500 A 3000 0 3335 200 Ioo0 n I I I I I I I 0 5o000 10,000 15,000 20,000 25,000 30,000 35,000 AIR FLOWRATE - SCFH Figure 15. Effect of air flow rate snd nozzle flow rate for Bete nozzle TF14FCN on the evaporation rate of water in the spray concentrator.

500H I -J w a: z 0 w IU 400 - Nozzle No. B 12 FC Runs 24-28, 41-Water _ _ Average Conditions wwwwwoolo 0000 Approximate Air Flowrate 32,000 scfh -0 30,000 scfh -v 29,000 scfh - 1 28,000 scfh - 0 300k Gas Flowrate Burner Temperature Cone Temperature 880scfh I I 0~F 67 0~F w Ir 500r 200k z 0 cr 0 0. LIJ I CO 1 Nozzle Flowrote Ibs./hr. 3000.Z 2500 doo 2000 400k I 00oo 30( I 3 I I I 28,000 32,000 AIR FLOWRATE - SCFH _ I I I I I I V - I I..... II a A-%,.RL.01%, _ J _ _ I U DUU 1000 1500 2000 2500 3000 3500 NOZZLE FLOWRATE - LBS./HR. Figure 16. Effect of air flow rate and nozzle flow rate for Bete nozzle B12FC on the evaporation rate of water in the spray concentrator.

500 Nozzle No. TF20 FCN Runs 32 8 33-Water Average Conditions m NL 0.r_ 0 QW 400 - Gas Flowrate Air Flowrate Burner Temperature Cone Temperature 8 64 scf h 33700 scfh 1080~F 700 OF 300H'j.. \J9 200H 100o I I I I I I I 1000 1500 2000 2500 3000 3500 4000 4500 Figure on the NOZZLE FLOWRATE - LBS./HR. 17. Effect of nozzle flow rate for Bete nozzle TF20FCN evaporation rate of weter in the spray 2cncentrator.

500 cl (I) _J I WU 400 300 ) )~ Nozzle No WRF 25 Runs 36-38 -Water m 0 Average Conditions Gas Flowrate Burner Temperature Cone Temperature i 840 scfh 1080~F 700~F z 0 0 0. 4> w 20C I 0 Approximate Air Flowrate scfh 0 24,140 A 28,240 0 30,770 I0( i r I I I I I I. _3 3500 0 500 1000 1500 2000 2500 3000 NOZZLE FLOWRATE- LBS./HR. Figure 18. Effect of air flow rate and nozzle flow rate on the evaporation rate of water in the spray concentrator.

" — " 1...-_ ~ ~ ----..._, —.... Recycle: / 400 =n__ i 0 O', - a —- Nozzle No. 82 FC ^~300^~ -- --- -- -- -- -- -- -— Runs 102-O07 or Steep Liquor z O~ Once-thru Corn Steep Uquor o Io~ ~~~~~~~~ \ ~~~Average Conditions 5-~ 200C- -830 scf h ~ Air Flowrate 4o50 ~F w Burner Temperature 00,WUAoo~~~,00Cone Temperature 30 oI 5 10 20 1 _ 0 BgY 5'10btri h0 CORN STEEP LIQUID CONCENTRATION WEIGHT PERCENT -.- -.r,. oe 9 E et r steep liquor con-eltrator. Fgthe pQ f e of o f c wtr in the spray cone-t the evaporation rate

concentrator but not recycled(. When Runs 26 (recycle) and')0 (.nce-thru) are compared, there is significant difference between the evaporation rates of 40c0. lb/hr and 2255.6 lb/hr, respectively. The sprayed water temperatures were 148~ and 65~F, respectively. Differences in air temperatures, fgas flow rates, and air flow rates make a precise comparison impossible, but the evaporation rate appears to be most significantly affectedr by the sp'rayed, water temperature. Mass transfer is limiting the evapornat-i on under} the operlat-:11ing, conditionso Seven runs were made with corn-s-teep liquor t evauiate t(he pe'r mance' of the spray concentrator with a mater'ial comlpa-rable t - s.i ckw:1 Ltr'.'T'he e Criisteep liquor concentrate contained appro ximatelyv')(/, b)y weight.l sl:i.s and hadl' to be diluted with water to approximate a stickwater solids concentration. Table IX contains the corn-steep liquor physical characteristics. TABLE IX PHYSICAL CHARACTERISTICS (F CORN-STEEP LIQUOR Solid s 5)4.25% as-received Soluble solids 50.03% as-received Suspended solids 4.22% as-received pH 5. Viscosity at 10.8% solids ambient temperature 1.19 Cp Five runs were made with once-thru fluid spray to determine the evaporation rate as a function of concentration. Runs 43-46 were conducted with the operating conditions nearly identical except for the corn-steep liquor concentration. Although there is some scatter in the data, there appears to be a slight decrease in evaporation rate with concentration as shown in Figure 19. No evidence of corn-steep liquor scorching was observed during the operations with the liquor. Some makeshift fiberglass insulation was wrapped around the connecting "T" during Runs 1-10 which were taken during the summer of 1971. Because it was difficult to maintain, it was removed during subsequent runs. The insulatioin did improve the thermal efficiency somewhat as can be seen frorr the data. Inr a permanent installation, the hot surfaces should' be insulaJted for improved thermal efficiency as well as for safety.

Three runs, Runs 29-31, were made with two nozzles being used as indicated in Table VI. The total flow rate was maintained at 3000 lb/hr. The purpose was to determine if greater spray coverage would improve the total evaporation capacity of the spray concentration. There was little, if any, difference between using a single nozzle or two nozzles. At the air flow rate through the chamber, the exit air is nearly saturated and the driving forces for evaporation becomes small. The experimental data in this report were processed with a digital computer program prepared for this investigation. A listing of the computer program is given in Appendix A. A sample calculation, giving the procedure used in the computer analysis, can be found after the computer listing. 39

CONCLUSIONS The conclusions of this investigation are summarized as follows: 1. The Blackmer Rotary, Pump, Model SNP 1/4 operated continuously, without trouble during testing. It provided adequate pressure. It should be adaptable to use on fish stickwater. 2. The present apparatus is capable of evaporating over 550 lb of water per hour with a fuel consumption of about 1,000,000 Btu/hr and an efficiency close to 6o%. It should be evident that the apparatus was not insulated so its efficiency could be improved. 3. The Bete-Fog nozzles produced fine drops and an essentially full cone of spray. These nozzles were chosen because they are designed to resist clogging. They should be applicable to spraying fish stickwater that is first screened to remove coarse particles. 4. Tests with corn-steep liquor (Table VIII), indicated that the presence of corn-steep liquor in the liquid being evaporated does not substantially affect the evaporation rate, fuel economy or other important operating variables even up to a concentration of 24. 30 corn-steep liquor. While this data cannot be extrapolated directly to apply to fish stickwater, they are an indication that the equipment should concentrate such wastes reasonably well. Obviously, the final phase of this study should include evaporation of fish stickwater. Funds, however, were not made available for such a study. 5. The operating experience on the spray concentrator indicated that nearly all the evaporation took place in the top 3 to 4 ft of the chamber. A design for a 10,000 gal/day fish stickwater spray concentrator is included in Appendix B. The design concept incorporates experience obtained in this investigation. 4o

LI ITRATIURE CITED (R-1) Kempe, Lloyed L., N. E. Lake, and R. C. Scherr. Disposal of Fish Processing Wastes, Final Report ORA Project N. 01431, The University of Michigan, July 1968. (R-2) Kempe, Lloyd L., Dale E. Briggs, William W. Freedman, and Michael Stenning. Spray Evaporation of Stickwater from Fish Rendering, Final Report ORA Project No. 026040, The University of Michigan, December 1971. (R-3) Tate, R. W. Sprays and Spraying for Process Use. Part I. Chem. Eng. 72 (July 19), 157-162 (1965); and Part II, 72 (August 2), 111-116 (1965). (R-4) Bete Fog Nozzles, Catalog No. 70, Bete Fog Nozzle, Inc., 332 Wells St., Greenfield, Massachusetts 01301. (R-5) Industrial Spray Nozzles, Catalog No. 1118A-1169 (1969). Delavan Manufacturing Co., 811 Fourth St., West Des Moines, Iowa 50265. (R-6) Eclipse Fuel Engineering Co., Combustion Division, Rockford, Ill., and Industrial Burner Co., 16911 Eight Mile R., Detroit, Michigan 48235. 41

APPENDIX A LISTING OF COMPUTER PROGRAM FOR PROCESSING DATA AND SAMPLE CALCULATION T4IS. P:UGRAM- TAKES DATA FROM THE EVAPORATOR RUNS AND COMPUTES C THE AMOUNT OF AIR NEEDED T3 COMPLETE THE MATERIAL BALANCE C C BELOW IS A LIST OF SYMBOLS USED IN THIS PROGRAM C C ATM - ONE ATMOSPHERE IN INCHES MERCURY L bTJ = BTJ!S PRODUCEOD Y COMBUSTION PER HUUR.C CF-A = CUBIC FEET OF AIR USED PER HOUR C DO33 DRY BULb TEMPERATURE OF OUTLET GASES C DI = DRY BULB TEMPERATURE OF INLET AIR GF F FINAL GAS READING IN CUBIC FEET C GI = INITIAL GAS READING IN CUBIC FEET HI = HUMIDITY UF INLET AIR IN LB. WATER/LB. DRY AIR C HIT = HUMIDITY UF AIR AT INLET IN LB. WATER/LB. WET AIR L H.O HUMIDITY (UF OUTLET GASES IN POUNDS WATER/POUND DRY GAS HOF= H UMIDITY OF OUTLET GASES IN VOLUME FRACTION C H3P = HUMIDITY UF OUTLET GASES IN VOLUME PERCENT -lOT = HUMIDITY OF OUTLET GASES IN LBS. WATER/LB. WET GAS C ITER = ITERATIONS USED TO APRUACH MOLECULAR WEIGHT OF DRY OUTLET GASES C MDGP = MULES (1F DRY GASES PRODUCED FROM COMBUSTION UF GAS C MEA = M3LES OF DRY AIR NOT USED IN COMBUSTION C MNG = MULES NATURAL GAS USED PER HOUR MPWI = MULE FRACTION OF WATER IN INLET AIR C MWA = AVERAGE MOLECULAR WEIGHT UF DRY AIR MWAI = MOLECULAR WEIGHT OF WET AIR AT INLET C MWDGO = MOLECULAR WEIGHT OF DRY GASES AT OUTLET C MWNG AVERAGE MOLECULAR WEIGHT OF NATURAL GAS C MWW = MOLECULAR WEIGHT OF WATER C NI = NJUBER OF TEMPERATURE MEASUREMENTS OF INLET AIR C NO = NUMBER CF TEMPERATURE MEASUREMENTS OF OUTLET GASES C NRUN = RUN NUMBER C PA = AMBIENT PRESSURE IN ATMOSPHERES PDA = PUUNDS OF DRY AIR USED PER HOUR C PG = PRESSURE OF GAS IN INHES WATER ABOVE AMBIENT PGA = ABSOLUTL PRESSURE OF NATURAL GAS IN ATMOSPHERES C PM = AMBIENT PRESSURE IN INCHES MERCURY C PWA = POJNDS WET AIR USED PER HOUR C R = GAS CONSTANT IN ATM*CUBIC FEET/LB.MOLE*DEGREE R C SCFA = STANDARD CUBIC FEET OF AIR USED PER HOUR C SCFG = STANDARI) CUBIC FEET OF GAS BURNED PER HOUR TAD = AVERAGE DRY BULB TEMPERATURE OF INLET AIR C TAW = AVERAGE WET BULB TEMPERATURE OF INLET AIR " TTG = TEMPERATURE OF GAS IN DEGREES F TGU = AVERAGE DY BULB TEMPERATURE OF OUTLET GASES C TGW = AVERAGE WET BULB TEMPERATURE OF OUTLET GASES TIM = TIME OF RUN IN MINUTES L TS = STANDARD TEMPERATURE IN DEGREES R C WE = WATER EVAPORATED IN LBS./HOUR C WET = TuTAL WATER EVAPORATED IN POUNDS C WI = WFT RULB TEMPERATURE OF INLET AIR C WNG = WEIGHT OF NATURAL GAS USED PER HUUR C WJ = WET BULB TEMPERATURE (]F OUTLET GASES L WPG = WATER PRODUCED FROM COMBUSTION OF GAS IN LBS. / HOUR C Z = CJMPRESSIBILITY FACTGR FOR WATER VAPOR UNDER OUTLET CONDITIONS C REAL MWNG, MWW, MWA, MPWI, MWDGO, MWAI, MNG, MDG;P, MEA DIMENSION WI(6), DI(6), WU(10), DBO(10) NAMELIST /DATA/ Wl, DI, WO, DBO, NI, NO, GF, Gl, TIM, WET, 1 ITEK, PG, PM, TG, NRUN 1 READ (5, DATA, END=999) WRITE (b,20U) NRUN, NI, NO G, G GI, TIM, WET, ITER, PG, PM, TG WUITE (6,201) (WIll, I=1, N1) WRITE (6,201) (0I(I), 1=1, NI) WRITE (6,201) (WO(I), I=1, NO) WRITE (6,201) (DBU( I),I=1, NO) R = 0.7302 Z = 0.99 MWW = 18.016 MWA = 29.03 42

INITIAL GUlESS f- MOLECULAR WEIGHT OF DRY GASt!S IN EXIT STREAM MWDGO = 29.4124 ATM - 29,92 rS = 520. MY4G = 16.51 HI = 0.0 HOP = 0.0 00 2 1=1, NI C C T-E FOLLOWING EQUATION IS A CURVE FIT OF HUMIDITY CHART AT WET C BJLB TEMPERATURES BETWEEN 50 & 75 DEGREES F 2 HI = HI+0.0001i*(-(0.0029667*(W ( I )+2.1247)*DI (I)+0.08443* i (WI (I) )*2-3.44985*W I(I)+153.7003) HI = HI/NI DO 3 I=1, NO C THE FOLLOWING EQUATION IS A CURVE FIT OF HUMIDITY CHART AT C WET BJLB TEMPERATURES BETWEEN 140 & 160 DEGREES F C 3 HUP = HtODP-.0001*(-1.041667*(WO(I) )**2+331.25*W0( I)-26033.33)* I Dt)(J) I)-0.011875*(WO( I) }**2+4.55625*W0 I)-3d7.7 HOF = HOP/(100.*NO) MPWI = (HI/MWW)/(HI/MWW+(l./MWA)) MWAI = MwA*(I.-MPWI) 4 MWW*AMPWI HIT = HI/(HI + 1.) PA PM/ATM PGA = PA +PG/(ATM*13.546) SCFG - TS*6b.O*PGAr*(G-GI )/(( TG+460.) TI M) WPG = O.095b*SCFG MNL = SCFG/(R*TS) WNG MNG*MWNG WE WL-T',60.0/T IM TAD = 0.0 TAW = 0.0 00 4 1=1, N1 TAW = TAW+WI( ) 4 AD TAI)D + D1(1) TAD = TA!)/NI TAW = TAW/NI TGD = 3.0 TGW = 0.0 00 6 I=1,NO TGD = TGI)+DBO(I) 6 TGW = TGw+WO(I) TGD = TGI)/NO TGW = TGW/NU MDGP = MNG*8.675 C ITERATION USING SUCCESSIVE SUSTIT ION TO FIND ACTUAL MULECULAR WEIGHT OF DRY GASES IN EXIT STREAM AND THUS AMOUNT OF AIR USED C dO 5 1=1, ITE r HO ( H(.F/( (.-HJF ) L))*MWW/MWDGO HUTf HU/(HO+l.) PWA ( WPG+WL-HU'(J*WE+WNG) ) /(H T-HITJ PDA: (1.-HIT)* PWA F A- PL)A/MWA-MNG*9.6 78 5 WDUO = (MEA*MWA+MDGP*30.0323)/(MEA+MDGPI LCA = R (TAO +460 ) *PWA/(MWAI*PA) SCcA = CFA*PA*TS/(460+TAU) tlTU = SCFG*1030. WRITE (6,202) HI, HO, SCFG, WE, CFA, SCFA, BTJ,TAD,TAW,TGDTGW GO TO 1 9V9 CALL tXIT 200 FOIMAT ('1NRNUN', 16/'NI =', I6/'NJ =', I6/ 1,GF =, f9.2/GI, F9.2/TIM =, F9.2/'WET, F9.2/' ITER', 16/'PG =', F9.2/'PM', F9.2/'TG', F9.2) 201 FORMAT {'0/101-8.1) 202 IFURMAT ('O'/' HI HO SCFG WE ICFA SC FA BTU TAD TAW TGD TGW 2/'/' ZF12.5,4: l2.2,Fll.1,4F10.2) LNU

Sample Calculation Run 20 Nozzle TF14FCN Experimental Data Duration of run: 127 min Inlet dry-bulb temperatures (~F): Inlet wet-bulb temperatures (~F): Outlet dry-bulb temperatures (~F): Outlet wet-bulb temperatures (~F): Flow through nozzle from rotameter: Initial gas reading: 30,102 ft3 Final gas reading: 32,085 ft3 Temperature of gas: 81.0~F Pressure of gas: 14.1 in H20 gauge Ambient pressure: 29.22 in. Hg Water added at 77~F: 769 lb 75.5, 75.0, 724.0, 72.5, 75.0 57.0, 5, 57.0, 5: 55.5, 5(.O 181.5, 179..0, 179.0, 180.0, 180.0, 184.5, 181.5, 177.0, 183.0 161.o, 159.0, 159.0, 160.0, 159.0, 162.0, 160.0, 159.0, 160.o 2500 lb H20/hr Mass Balance to Obtain Air Flow A mass balance on the water gives: Water out/hr = Water in/hr + water produced/hr Water out/hr = XoGo where: X = lb water/lb wet outlet gas Go = lb wet gas out/hr 44

but since Go is the only outlet Go = total mass in./hr Go = We + N.G. +Awi where: We = mass water evaporated/hr N.G. = mass of natural gas used/hr Awi = mass of' wet a-ir in./hr Water out/hr = Xo(We + N.G. + Awi) Water in/hr + water produced/hr = We + Xi Awi + Wg where: X = lb water/lb set inlet air Wg = lb water produced from combustion/hr Thus: Xo(We + N.G. + Awi) = We + Xi Awi + Wg Wg + We - Xo(We + N.G. Awi = X XO - Xi o 1 Thus: Xi, Xo, We, N.G., and Wg must be derived from data. Calculated Results e i t h* 0.00o63 + 0.0059 + 0.0054 + o.oo56 + 0.0058 Average inlet humidity* = Average inlet humidity = 0.0059 lb water/lb dry air 0.0059 lb water/lb dry air Pound,~; water/lb wet air = u(at i* L etl) /,i 0.0059 lb water/lb dry air + 1 lb dry air/lb dry air (at inlet) Pounrlds wLter/lb wet a:ir (Xi) = 0.0059 lb water/lb set air (nt irllet) x-'il'ken f' rm Air Pollution Engineering Manual U. S. Department of Health, Education, and Well'are?,KtO-AP-40. Charts were curve fit to equations which were corrected'or average pressure. 45

Average outlet humidity* (in volume fraction).526c + 0.3114 + 0.5114 + 0.3190 + 0.3111 + 0.5584 + 0.5186 + 0.3120 + 0.53181 9.3180 ft3 water ft3 wet gas Humidity of oulet gases (using 29.412 lb/mole as average molecular weight of dry gases out and.99 as compressibility of steam) -= |_.53180 ft, water/ft3 wet gas / j l 7o moe dry as * f't water ((1.0 -.5180) ftt dry gas/ftO wet gas) 99 mole yfmole water * ft dry gas 18.016 lb water/lb mole 29.4124 lb dry gas/lb mole Humidity of outlet gases =.2885 lb water/lb dry gas Pound water/lb wet outlet gas =.2885 lb water/lb dry gas 1.0 lb dry gas/lb dry gas +.2885 lb water/lb dry gas Pound water/lb wet outlet gas (Xo) =.2239 lb water/lb wet gas ed/hr = (769.5 lb water)(60 min/hr) lb water Water evaporated/hr (We) 127 min= 35=.5 hr 127 min hr 29.22 in. Hg Absolute pressure of gas = 2 i + 29.92 in. Hg 14.10 in. H20 (29.92 in. Hg/atm)(13.546 in. H20/in. Hg) *Taken from Air Pollution Engineering Manual U. S. Department of Health, Education, and Welfare 999-AP-40. Charts were curve fit to equations which were corrected for average pressure.

Absolute oressure cf gas = 1.0114 atm Gas flcw rate (520~R)(0.0114 atm)(32085 ft3 - 30102 ft3)(60 min/hr) (81 + 460)~R (127 min)(l atm) Gas flow rate = 910.7 standard ft3 gas/hr 1910-7 standard. ft Moles gas used (910.74 ft3/hr)(l atm) (0.7502 atm ft3/lb mole ~R)(5200R) = 2.399 moles/hr Pounds gas used (iT.G.) = (16.507 lb/lb mole)(2.399 moles/hr) = 39.600 lb/hr Water produced by combustion of natural gas (Wg) = (910.7 ft3 gas/hr)(0.0956 lb H20/ft3 gas) = 87.06 Wet air in (Awi) = 87.06 lb water/hr+ 63.5 lb water/hr -.2239 lb water/lb wet gas (363.5 lb water/hr + 39.6 lb N.G./hr).2239 lb water/ lb wet gas -.0059 lb water/lb wet air = 1652.8 lb wet air/hr Since molecular weight of dry gases out was just a guess and was used in calculations, an iterative process is needed to obtain correct value. A new molecular weight for the dry gases out must be obtained by using the results of the previous iteration. Dry air in = [(1.0 - 0.0059) lb dry air/lb wet air][1652.8 lb wet air/hr] = 1643.05 lb dry air/hr

Moles air not used in combustion = 1643.05 lb dry air/hr / moles gas 7 moles dry a ir\ 29.03 lb dry air/lb mole dry air -.3'9 hr A mole gas moles dry air = 33.381t hr Moles of dry gas that would result from a complete combustion of the natural gas with stoichiometric air = - 399 mol / as )\ (8 75 moles dry gas) = (2.99 moles gas/hr) 8.675 mole natural gas mole natural gas, 20.811 moles dry gas hr -O00 New molecular weight of dry gas out (33.381 moles dry air/hr)(29.03 lb/lb mole dry air) + (20.811 moles dry gas/hr)(30.0323 lb/lb mole dry gss) (33.38 moles dry air/hr + 20.811 moles dry gas/hr) New molecular weight of dry gas out = 29.4154 New humidity of outlet gases = I 0.3180 ft3 water/ft3 we tt gas 18.016 lb water/lb mole 29.4154L lb dry gss /lb mo le [(1.0 -.5180) ft3 dry gas/ft3 wet gas].99 mole dry gas ft water ~ ~. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Z i mole water * ft2 dry gas_ New humidity of outlet gases =.2885 lb water/lb dry gas

-his is the same as original humidity so no iterations are needed. In some cases two or more iterations are reqCured. io:le fraction of water in inlet air = 0.0059 lb water/lb dry air 18.01 lb water/lb mole 0.0059 lb water/lb dry air 1.00 lb dry air/lb dry air 18.016 lb water/lb mole 29.03 lb dry air/lb mole 0.0094 lb moles water lb mole wet air Molecular weight of wet air in = 29.0 lb (1.0 - lb mole dry air + lb mole dry air lb mole wet air 18.016 lb lb mole water lb m e water (0.0094)b me wet air lb mole water lb mole wet air Molecular weight of wet air in = 28.9262 lb/lb mole wet air Average temperature of air in = 73.5 + 75.0 + 74.0 + 72.5 + 73.0 5 = 73.6~F Volume air used = (0.7309 atm ft3/lb mole OR)(73.6 + 460)~R)1652.8 lb wet air/lb) (28.9262 lb/lb mole wet air) (29 atm 29. 92, = 22,797 ft3/hr

ft~ 29.22 in H ( ) 7... ^ - - ^l2^97 Thr 2g9.92 in. Hg E) R 7Volume air used corrected to standard conditions =( -2- in. H ( —-- 460 + 73.5') 0R ft> = 21,696 h hr Heating value of gas = 1030 Btu/ftj Energy released = (910.7 SCFH)(1030 Btu/SCF) = 938,000 Btu/hr Energy absorbed = (363.45 lb water/hr)(1084.9 Btu/lb water) = 394,300 Etu/hr Efficiency = 394,300 Btu/hr 938,000 Btu/hr x 1 2 c 0 3 63. 545 Ib/hr Fraction water evaporated pass = 3563.4 lb/hr 2500 lb/hr 0.145

APPENDIX B SUGGESTED DESIGN OF A MODIFIED 10,000-GALLON PER DAY SPRAY CONCENTRATOR DE'SIGN BASES:i Process 10,000 gallons/day of fish stick liquor in 24 hr with a density of 1.015 g/ml at 5% solids by weight to produce a product containing 350 solids. Feed temperature: Inlet air: Outlet air: Air flow rate: Nozzle flow rate/evaporation rate: Energy efficiency: 60~F 60~F 200~F 110 standard cu ft/lb water evap 10 50% WATER EVAPORATION REQUIRED'eed weight = 10,000 gal/day lb wpater 8.3 3.gal gal 1.015 g/ml 1.000 g water/ml = 84,600 lb/day Weight solids = (0.05)(84,600) = 4,270 Weight product 270 142 0.30 Wnter evaporated = 84,600 - 14,230 = 70,370 lb/day = 2,930 lb/hr

NOZZcLE FLOW RATE Nozzle! flow rate = 10(2,920) = 29, 300 lb/hr 29,300 lb/hr ( 1.00 g wnter/ml) (8.33 lb water/gal)(1.015 g/ml)( 0( mm/hr) = 57.7 gpm AIR FLOW RATE11: Air flow rate = 110 SCFH/lb water evap (2,930 lb/hr) = 322,000 SCFH ENERGY ABSORBED Air: Q = m Cp At m = 522,000 SCFH (0.0765 lb/SCFH) m = 24, 00 lb air/hr Q, = (2J, ("),0 lb/hr)(0. 2'4 Btu/lb)(200"' - (0"~11') Q = 825,000 Btu/hr Water: Q Q m(Hvapor - Hfeed) = 2, 90 lb/hr (1145.9 Btu/lb - 28.1 Btu/lb) Q = 3,275,000 Btu/hr Qtotal = 825,000 + 3,275,000 = 4,100,000 Btu/hr ENERGY REQUIRED':4, I.100 00 1f,1 (.)I ltl.V - ('). I q() - (),-0()0, 0 (()() 1I-,O' /hr (} y

1 l C 0 Ii olid{1)KD _DESIGN Use three nozzles with a flow rate of 20 gpm for each nozzle at a pressure drop across each nozzle of 40 psi. The spray angle should be 75~. The nozzle layout should be as shown in Figure B-l. A schematic of the spray concentrator is also given in Figure B-1. Nozzle Feed Line > x,Spray Coverage I,'-'-"'-' "\ 3-Nozzles (\{ i\ ^ \ Tyon Equilateral 0v ^*~ l\ i ~s^ Triangle Layout Hot Combustion Gases K-3H 3 -* Nozzle Feed Line Outlet Gases'9" Concentrated Fish Stick Liquor Figure B-1. Schematic drawing of recommended spray concentrator showing nozzle layout. 53

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