NEW PROCESSES FOR THE SEPARATION OF WATER FROM AQUEOUS SYSTEMS

Abstract

Processes for the separation of water from a mixture of water with other components, comprising the following steps: A) providing feed material FM comprising water and at least one a nonionic surfactant S in an amount of 0.1 to 1000 ppm by weight based on the feed material FM, B) subjecting said feed material FM to a distillation step using a falling film evaporator.

Claims

1: A process for separating water from a mixture of water with at least one other component, the process comprising: providing a feed material comprising water and at least one nonionic surfactant in an amount of 0.1 to 1000 ppm by weight based on the feed material, and carrying out distillation of the feed material with a falling film evaporator.

2: The process according to claim 1, wherein the distillation is carried out as a multieffect distillation.

3: The process according to claim 1, wherein the feed material further comprises at least one polymer A that is a polymer of at least one ethylenically unsaturated mono carboxylic acid and/or at least one ethylenically unsaturated dicarboxylic acid in an amount of 0.1 to 1000 ppm by weight based on the feed material.

4: The process according to claim 1, wherein the feed material further comprises at least one polymer that is a block copolymer comprising at least one polyolefinic block and at least one polyalkylene oxide block in an amount of 0.01 to 100 ppm by weight based on the feed material.

5: The process according to claim 1, wherein the at least one nonionic surfactant is a polyalkylene oxide.

6: The process according to claim 5, wherein the polyalkylene oxide is selected from the group consisting of an alkoxylate of a monoalcohol and a copolymer of at least two alkylene oxides.

7: The process according to claim 1, wherein the nonionic surfactant is selected from the group consisting of an alkoxylate of a linear or branched C.sub.4-C.sub.26 alcohol and a block copolymer comprising blocks of polyethyleneoxide and polypropylene oxide.

8: The process according to claim 1, wherein the nonionic surfactant has a molar mass of from 500 to 6000 g/mol.

9: The process according to claim 1, wherein the at least one nonionic surfactant is a long-chain aliphatic alcohol.

10: The process according to claim 1, wherein said nonionic surfactant has an ability to reduce a contact angle of water on a surface of a tube material by 1 to 40 degrees.

11: The process according to claim 10, wherein the process is carried out as a multi effect distillation and wherein the tube material is selected from the group consisting of aluminum brass, titanium, stainless steel, an alloy of copper/nickel, an alloy of aluminum/magnesium, a metal comprising a ceramic coating, and a polymer composite comprising graphite and at least one organic polymer.

12: The process according to claim 1, wherein the feed material is a solution of sugar, salt water, brackish water or brine obtained in at least one waste water treatment operation.

13: A formulation, comprising: from 0.1 to 99% by weight of at least one nonionic surfactant, which is a polyalkyleneoxide, from 0.1 to 99% by weight of at least one polymer that is a polymer of at least one ethylenically unsaturated mono carboxylic acid and/or at least one ethylenically unsaturated dicarboxylic acid, from 0 to 50% by weight of at least one polymer that is a block copolymer comprising a polyolefinic block and at least one polyalkylene oxide block, and from 0 to 80% by weight of water.

14: The process according to claim 6, wherein the monoalcohol is an alkoxylate of a monoalcohol.

15: The process according to claim 1, wherein the nonionic surfactant is a polyalkyleneoxide which has a structure PEO-PPO-PEO, PPO-PEO-PPO, PEO-PBO-PEO or PEO-pTHF-PEO.

16: The process according to claim 6, wherein the wherein the monoalcohol is at least one selected from the group consisting of n-decanol, iso-decanol, 2-propylheptanol, tridecanol, octadecanol, butanol, hexanol, nonanol, undecanol, 2-ethylhexanol, isodecanol and isononyl alcohol.

Description

EXAMPLES

[0202] Materials Used: [0203] Nonionic Surfactant 1: C.sub.9-C.sub.11 Oxoalkohol alkoxylated with a molar average of 7 EO units and 1.5 butylene oxide units (block copolymer alkoxylated in the order given). [0204] Nonionic Surfactant 2: alkoxylated fatty alcohol containing higher alkene oxides and ethylene oxide bearing a terminal OH group. [0205] Nonionic Surfactant 3: C.sub.10 Oxoalkohol alkoxylated with a molar average of 10 EO units and 1.5 mol pentene oxide, prepared according to the procedure given in WO 03/090531, p. 34, In 24-36 (comparative example 3). [0206] Nonionic Surfactant 4: 2-propylheptyl alcohol alkoxylated with a molar average of 5.7 EO and 4.7 PO, prepared analogously to the procedure given in WO 2005/37757, p. 13, In 6-23 (example 1). [0207] Nonionic Surfactant 5: 2-propylheptyl alcohol alkoxylated with a molar average of 5.7 EO, 4.7 PO and 2.3 EO, prepared analogously to the procedure given in WO 2005/37757, p. 13, In 6-23 (example 1). [0208] Nonionic Surfactant 6: C.sub.13 Oxoalkohol alkoxylated with a molar average of 27 EO units and 1 PO units and esterified with C.sub.8-C.sub.18 fatty acid, prepared according to the procedure given in WO06/097435 on page 20 In 20 to P. 21, In 8 (example 1). [0209] Nonionic Surfactant 7: Block copolymer in which the central polypropylene glycol group is flanked by two polyethylene glycol groups, wherein the central polypropylene block has a molar mass of 1750 g/mol and wherein the weight percentage of polyethylene glycol in the polymer is 20%, the molar mass of the nonionic surfactant is 2450 g/mol (calculated from OH number), the viscosity (EN 12092, 23 C., Brookfield, 60 rpm) is 500 mPas, the wetting is (EN 1772, 23 C., 2 g/l soda ash, 1 g/l surfactant) is >300 s and the surface tension (EN 14370, 1 g/l, 23 C., under application of Harkins-Jordan correction) is 41 mN/m. [0210] Nonionic Surfactant 8: Block copolymer in which the central polypropylene glycol group is flanked by two polyethylene glycol groups, wherein the central polypropylene block has a molar mass of 1750 g/mol and wherein the weight percentage of polyethylene glycol in the polymer is 40%, the molar mass of the nonionic surfactant is 2900 g/mol (calculated from OH number), the viscosity (EN 12092, 23 C., Brookfield, 60 rpm) is 1000 mPas, the wetting is (EN 1772, 23 C., 2 g/l soda ash, 1 g/l surfactant) is >300 s and the surface tension (EN 14370, 1 g/l, 23 C., under application of Harkins-Jordan correction) is 41 mN/m. [0211] Nonionic Surfactant 9: Block copolymer in which the central polypropylene glycol group is flanked by two polyethylene glycol groups, wherein the central polypropylene block has a molar mass of 2750 g/mol and wherein the weight percentage of polyethylene glycol in the polymer is 20%, the molar mass of the nonionic surfactant is 3650 g/mol (calculated from OH number), the viscosity (EN 12092, 23 C., Brookfield, 60 rpm) is 900 mPas, the wetting is (EN 1772, 23 C., 2 g/l soda ash, 1 g/l surfactant) is 100 s and the surface tension (EN 14370, 1 g/l, 23 C., under application of Harkins-Jordan correction) is 35 mN/m. [0212] Nonionic Surfactant 10: Block copolymer in which the central polyethylene glycol group is flanked by two polypropylene glycol groups, wherein the central polyethylene block has a molar mass of 430 g/mol and wherein the weight percentage of polyethylene glycol in the polymer is 20%, the molar mass of the nonionic surfactant is 2150 g/mol (calculated from OH number), the viscosity (EN 12092, 23 C., Brookfield, 60 rpm) is 450 mPas, the wetting is (EN 1772, 23 C., 2 g/l soda ash, 1 g/l surfactant) is >300 s and the surface tension (EN 14370, 1 g/l, 23 C., under application of Harkins-Jordan correction) is 38 mN/m. [0213] Nonionic Surfactant 11: Block copolymer in which the central polypropylene glycol group is flanked by two polyethylene glycol groups, wherein the central polypropylene block has a molar mass of 930 g/mol and wherein the weight percentage of polyethylene glycol in the polymer is 30%, the molar mass of the nonionic surfactant is 3100 g/mol (calculated from OH number), the viscosity (EN 12092, 23 C., Brookfield, 60 rpm) is 600 mPas, the wetting is (EN 1772, 23 C., 2 g/l soda ash, 1 g/l surfactant) is >300 s and the surface tension (EN 14370, 1 g/l, 23 C., under application of Harkins-Jordan correction) is 40 mN/m. [0214] Nonionic Surfactant 12: sorbitan monostearate alkoxylated with a molar average of 20 EO units, OH number 81-96, saponification number (ISO 3657) 45-55. [0215] Antiscalant 1: Modified Polycarboxylate, sodium salt with a density (DIN 51757, 23 C.) of 1.26 g/cm.sup.3 and a viscosity (DIN 53018, Brookfield, 60 rpm, 23 C.) of 200 mPas.

I. Test Rig

[0216] A horizontal tube falling film evaporation in pilot plant scale was employed in order to test the film flow characteristics of falling seawater films and scale formation of heated tube surface under conditions that are close to those prevailing in industrial multiple-effect distillers (MED).

[0217] The schematic diagram of the pilot plant scale test rig is shown in FIG. 1 (A=Vacuum pump; B=Collecting tank; C=Condensate; D=Distillate; E=Brine; F=Collecting tank; G=Recirculation pump; H=Sampling; I=Seawater; J=Vapour; K=Condenser; L=Electric steam generator; M=Steam).

[0218] The pilot scale test rig comprised a horizontal tube falling film evaporator fitted with a bank of 6 horizontal tubes arranged below each other with a tube pitch of s=50 mm as shown in FIG. 2. Saturated steam from an electrical steam generator was introduced into the tubes and condensed under vacuum conditions while the heat was transferred to the evaporation side. The test liquid was evenly distributed onto the first tube by means of a toothed overflow weir and trickles down by gravity forming a thin film flow over the horizontal tubes. The enthalpy of condensation was used to preheat the test liquid to the boiling point on the upper tube and then part of it to be evaporated on the lower tubes. The generated vapor was condensed in a plate heat exchanger. After leaving the evaporator, the test liquid flowed into a collecting tank and was mixed with the distillate. Then the test liquid was recirculated by a pump.

[0219] Carbon dioxide released from evaporating seawater and ambient air potentially penetrated into the evaporator were extracted by means of a vacuum pump which maintained the saturation pressure in the evaporator shell. The pilot plant provided conditions for CO.sub.2 release from seawater very similar to those in industrial multiple-effect distillers (MED). Carbon dioxide release shifted the pH value of the seawater to higher values and influenced the carbonate system.

[0220] The test rig was equipped with various temperature, pressure, and flow rate measuring devices in order to monitor and control the process as shown in FIG. 1. Control of the apparatus was completely automatic in order to maintain continuous, steady operation over long periods which is essential to obtain reproducible scaling results.

[0221] The tubes could be removed from the tube sheets in order to renew the tubes, to test different tube materials, and to analyze the adherent scale. On both sides of the evaporator, inspection glasses were installed which allow for a visual observation of the wetting behavior.

II. Test Materials

[0222] Artificial seawater was used in test series for investigating scale formation. Deionized water was used in test series for investigating the wetting behavior of different tube materials and the impact of Nonionic Surfactant S on the tube wetting behavior.

[0223] The preparation of artificial seawater was based on salt mole fractions for standard artificial seawater as suggested in the formulation by Kester et al. (Kester, D. R.; Duedall, I. W.; Connors, D. N.; Pytkowicz, R. M., Preparation of artificial seawater, Limnology and Oceanography, 12 (1967) 176-179).

[0224] The tube material surfaces were characterized by measuring contact angles of artificial seawater with salinity of 45 g/kg at temperature of 70 C. The impact of Nonionic Surfactant S on the contact angle was measured with dilute solution of Nonionic Surfactant S in the artificial seawater with salinity of 45 g/kg. The concentration of Nonionic Surfactant S was 100 ppm by weight based on the solution.

[0225] Scaling experiments were performed with artificial seawater having a salinity of 65 g/kg simulating the concentrated seawater on the bottom tubes in industrial MED plants taking into account a typical concentration factor between 1.3 and 1.6. Seawater with a salinity of 65 g/kg has an ionic strength of 1.39 mol/kg.

[0226] Table 1 shows the amount of different salts which were used to prepare the artificial seawater with salinity of 65 g/kg and Table 2 shows the concentration of different ion present in the artificial seawater. After mixing the salts and stirring the solution, the artificial seawater was aerated. The aeration tended to equilibrate the solution with atmospheric gases and removed the excess CO.sub.2 resulting from the conversion of HCO.sub.3.sup. to CO.sub.3.sup.2. The pH of the artificial seawater after aeration was between 8.1 and 8.3.

TABLE-US-00001 TABLE 1 Formula for 1 kg artificial seawater with salinity of 45 g/kg and 65 g/kg Salinity = 45 g/kg Salinity = 65 g/kg Salt g per kg of solution g per kg of solution NaCl 30.762 44.434 Na.sub.2SO.sub.4 5.153 7.443 KCl 0.870 1.257 NaHCO.sub.3 0.252 0.364 KBr 0.126 0.182 H.sub.3BO.sub.3 0.033 0.048 NaF 0.004 0.006 MgCl.sub.26H.sub.2O 13.926 20.115 CaCl.sub.22H.sub.2O 1.953 2.821 SrCl.sub.26H.sub.2O 0.031 0.045 Deionized water to 1,000.000 g

TABLE-US-00002 TABLE 2 Composition of ions in artificial seawater with salinity of 45 g/kg and 65 g/kg Salinity = 45 g/kg Salinity = 65 g/kg Ion Concentration (g/kg) Concentration (g/kg) Cl.sup. 24.882 35.941 Na.sup.+ 13.841 19.992 SO.sub.4.sup.2 3.486 5.035 Mg.sup.2+ 1.665 2.405 Ca.sup.2+ 0.532 0.769 K.sup.+ 0.496 0.719 HCO.sub.3.sup. 0.183 0.264 Br.sup. 0.085 0.123 Sr.sup.2+ 0.010 0.015 H.sub.3BO.sub.3 0.033 0.048 F.sup. 0.001 0.002

III. Tube Materials

[0227] The horizontal tubes used in the experiments were made of copper-nickel 90/10, aluminium alloy AlMg2.5 (containing 2.4-2.8% magnesium), or aluminium brass.

[0228] The outer diameter of the tubes was d.sub.0=25 mm. The effective length was L=453 mm. For studying the wetting behavior and scale formation, unless stated otherwise the tubes were used with their typical surface topography as delivered by the tube suppliers. For some specific wetting and scale formation tests, the copper-nickel 90/10 tube was pretreated by soaking it in artificial seawater with salinity of 65 g/kg for 8 weeks prior to be used in the tests. This pretreatment caused the formation of a thin, adherent, protective surface film which is complex, multilayered and mainly comprised of cuprous oxide on the copper-nickel 90/10 tube surface. The pretreated copper-nickel 90/10 tube is denoted as CuNi 90/10-PT. The surface roughness was determined using a tactile stylus unit (perthometer) according to DIN EN ISO 4288. The tube materials, thermal conductivities, outer diameters, wall thicknesses, and surface roughnesses are summarized in Table 3.

TABLE-US-00003 TABLE 3 Physicochemical data of the horizontal tubes/Thermal Conductivity determined according to the procedure given in; Mller-Steinhagen, H., Fouling of Heat Exchanger Surfaces, In: VDI Heat Atlas, VDI-Gesellschaft (ed.), Springer-Verlag, Berlin Heidelberg, 2013, pp. 91-121); UNS No.: Unified Numbering System No. for metal alloys. Thermal conductivity Outer diameter Wall thickness Surface roughness Alloy UNS No. (W/(m K)) (mm) (mm) R.sub.a (m) CuNi 90/10 C70600 52 (20 C.) 25 1.0 0.28 60 (100 C.) AlMg2.5 A95052 134/140 (0 C.) 25 1.25 0.46 146 (100 C.) Al brass C68700 100 (20 C.) 25 1 0.44 112 (100 C.)
IV. Tube surface characterization

[0229] The tube material surfaces were characterized by measuring contact angles of artificial seawater with salinity of 45 g/kg prepared according to the procedure given in section II of the experimental part at temperature of 70 C. using an OCA 15 Pro contact angle measuring and contour analysis instrument manufactured by Dataphysics according to DIN 55660-2. The impact of nonionic surfactant S on the contact angle was measured with dilute solution of Nonionic Surfactant S in the artificial seawater. The concentration of Nonionic Surfactant S was 100 ppm by weight based on the solution. Before measuring the contact angle, the surface was thoroughly cleaned with isopropyl alcohol to remove any deposits, grease, oil, etc. The advancing contact angle was measured using a sessile drop method according to DIN 55660-2. A sessile drop was formed on the surface by means of a syringe needle and the volume of the drop was slowly increased. In doing so, the interface migrates outwards. One second after the drop was placed on the surface, the image of the liquid droplet was digitized by means of a CCD camera and a data processing system. A contour recognition was initially carried out and afterwards the drop shape was fitted to the contour. The angle formed between the liquid/solid interface and the liquid/vapour interface was taken as the contact angle. Table 4 shows the impact of nonionic surfactant S on contact angle of artificial seawater with salinity of 45 g/kg at temperature of 70 C. on different tube surfaces.

TABLE-US-00004 TABLE 4 The impact of Nonionic Surfactant S on contact angle of artificial seawater with salinity of 45 g/kg at temperature of 70 C. on different tube surfaces. Contact angle difference () on material surface* Nonionic surfactant S CuNi 90/10 AlMg2.5 Nonionic Surfactant 1 25 18 Nonionic Surfactant 2 27 10 Nonionic Surfactant 3 30 4 Nonionic Surfactant 4 28 10 Nonionic Surfactant 5 27 5 Nonionic Surfactant 6 16 2 Nonionic Surfactant 7 26 16 Nonionic Surfactant 8 27 9 Nonionic Surfactant 9 22 6 Nonionic Surfactant 10 25 4 Nonionic Surfactant 11 30 11 *Contact angle difference () = contact angle of 100 ppm Nonionic Surfactant S solution in artificial seawater with salinity of 45 g/kg - contact angle of artificial seawater with salinity of 45 g/kg.

V. Tube Wetting Experiments

[0230] The wetting behavior of different tube materials with different Nonionic Surfactants was investigated using the test rig described above. Prior to each test, the tube surface was thoroughly cleaned with soap solution, rinsed with deionized water and cleaned again with isopropyl alcohol to remove any deposits, grease, oil, etc. The wetting experiments were conducted using deionized water containing Nonionic Surfactant S with concentration of 1 and 100 ppm by weight based on the solution as given in table 5. The wetting experiment were conducted as follows: starting with completely dry tube surfaces, the wetting rate was stepwise increased with increments of about 0.005-0.01 kg/(s m). At each wetting rate, pictures were taken of the film flow over the top 5 tubes after 10 minute relaxation time. The percentages of the wet surface areas on the tube surfaces were evaluated by means of an image processing software. The top tube was not taken into account in the picture analysis because it was observed that the top tube serves as some sort of distribution tube for the liquid flow. The film flow over about 63% of the tube length was considered in the picture analysis. The non-relevant areas between adjacent tubes were cut off with a graphics editing software (Adobe Photoshop, Adobe Systems, USA). Afterwards the dry patches were marked with an image processing software (ImageJ, National Institutes of Health, USA) and the percentages of the wet surface area were calculated. The wetting tests were performed without inspection glasses at ambient pressure and temperature which was 27-34 C.

[0231] The test conditions and the test results of wetting behavior of different tube materials with different surfactants S are presented in Table 5.

TABLE-US-00005 TABLE 5 The results of wetting test on different tube materials Critical Concen- wetting tration Tube rate* Exp. No. Nonionic Surfactant S (ppm) material (kg/(s m)) V.1 Without nonionic AlMg2.5 0.050 surfactant S V.2 Nonionic Surfactant 3 1 AlMg2.5 0.040 V.3 Nonionic Surfactant 7 1 AlMg2.5 0.025 V.4 Nonionic Surfactant 6 1 AlMg2.5 0.100 V.5 Without nonionic CuNi 90/10 0.165 surfactant S V.6 Nonionic Surfactant 3 1 CuNi 90/10 0.120 V.7 Nonionic Surfactant 7 1 CuNi 90/10 0.070 V.8 Nonionic Surfactant 7 2.5 CuNi 90/10 0.080 V.9 Nonionic Surfactant 7 100 CuNi 90/10 0.080 V.10 Nonionic Surfactant 6 1 CuNi 90/10 0.040 V.11 Nonionic Surfactant 1 CuNi 90/10 0.070 6:Nonionic Surfactant 12 (9:1) V.12 Nonionic Surfactant 1.11 CuNi 90/10 0.060 6:Nonionic Surfactant 12 (9:1) V.13 Without nonionic CuNi 90/10-PT 0.120 surfactant S V.14 Nonionic Surfactant 7 1 CuNi 90/10-PT 0.052 V.15 Without nonionic Al brass 0.032 surfactant S V.16 Nonionic Surfactant 3 1 Al brass 0.020 V.17 Nonionic Surfactant 7 1 Al brass 0.020 V.18 Nonionic Surfactant 1.11 Al brass 0.020 6:Nonionic Surfactant 12 (9:1) *wetting rate is defined as the falling film mass flow rate on one side or on both sides of a horizontal tube per unit tube length. Herein, the wetting rate is expressed as the mass flow rate on both sides of a horizontal tube per unit tube length. The critical wetting rate is wetting rate necessary to reach fully wetted conditions on the tube surface.

VI. Scaling Experiments

[0232] All scale formation experiments were performed with 240 liters of artificial seawater with a salinity of 65 g/kg prepared according to the procedure given in section II of the experimental part for a test period of 50 hours. The experiments with 240 liters of test solution and a test period of 50 hours were found to be favorable because the period is long enough to find differences in scale formation and supersaturation levels are still high enough. The scaling experiments were performed at an evaporation temperature (t.sub.EV)=65 C. which represents the current top brine temperature in MED plants. Furthermore, in order to consider a possible extension of the operating range of multiple-effect distillers towards higher top brine temperatures, experiments were performed at an evaporation temperature (t.sub.EV)=75 C. exceeding the top brine temperature currently used in industrial MED distillers. For all experiments, the difference between the condensation temperature t.sub.CO inside the tubes and the evaporation temperature t.sub.EV outside the tubes was t.sub.COt.sub.EV=5 C.

[0233] The crystalline scale layers formed on the outside of the tubes of the evaporator were characterized by various methods to obtain chemical, structural, and quantitative information. The scale formed on the fifth tube from the top of the tube bank was analysed using scanning electron microscopy (SEM) in combination with energy dispersive X-ray spectroscopy (EDXS) and wide angle X-ray diffraction (XRD) to provide qualitative information on structural and chemical characteristics/properties of the scale, especially about composition, crystal structure, crystal size and orientation, and crystal perfection. The amounts of calcium and magnesium in the scale were detected by inductively coupled plasma atomic emission spectroscopy (ICP-AES). To this end, the scale of the fourth tube was dissolved in a hot solution of acetic acid and the concentrations of Ca.sup.2+ and Mg.sup.2+ ions in the solution were measured using ICP-AES. Based on the concentration of Ca.sup.2+ and Mg.sup.2+, the scale contents were calculated and presented as masses of Ca and Mg per total tube area (g/m.sup.2). Additionally, the scale thickness was determined on the outside of the third tube. It was measured 10 times each at 4 different positions around the tube and at 9 different positions along the tube with a gauge (MiniTest 2100, ElektroPhysik, Germany) designed for non-destructive and precise coating thickness measurement.

[0234] The test conditions and the test results of scaling experiments are presented in Table 6. The SEM images of the tube surface are presented in FIG. 3-6.

[0235] FIG. 3: SEM image of scale formed on AlMg2.5 tube surface with wetting rate=0.02 kg/(s m) without nonionic surfactant S and polymer A

[0236] FIG. 4: SEM image of clean AlMg2.5 tube surface with wetting rate=0.02 kg/(s m), Nonionic Surfactant 7 (2.5 ppm) and Antiscalant 1 (4 ppm)

[0237] FIG. 5: SEM image of scale formed on AlMg2.5 tube surface with wetting rate=0.04 kg/(s m) without nonionic surfactant S and antiscalant

[0238] FIG. 6: SEM image of clean AlMg2.5 tube surface with wetting rate=0.04 kg/(s m), Nonionic Surfactant 7 (2.5 ppm) and Antiscalant 1 (4 ppm)

TABLE-US-00006 TABLE 6 Mg scale Scale Film Tube t.sub.EV/t.sub.CO Nonionic Surfactant Ca scale content content thickness break- No. material ( C.) (Kg/(s m)) S (ppm) Antiscalant (ppm) (g/m.sup.2) (g/m.sup.2) (m) down VI.1 AlMg2.5 65/70 0.02 w/o w/o 3.97 0.13 7.1 Yes VI.2 AlMg2.5 65/70 0.02 w/o Antiscalant 1 1.25 0.13 9.2 Yes (4 ppm) VI.3 AlMg2.5 65/70 0.02 Nonionic Surfactant w/o 0.38 0.01 NA No 7 (2.5 ppm) VI.4 AlMg2.5 65/70 0.02 Nonionic Surfactant Antiscalant 1 0.04 0.00 NA No 7 (2.5 ppm) (4 ppm) VI.5 AlMg2.5 65/70 0.04 w/o w/o 10.73 0.26 No VI.6 AlMg2.5 65/70 0.04 w/o Antiscalant 1 0.06 0.04 No (4 ppm) VI.7 AlMg2.5 65/70 0.04 Nonionic Surfactant w/o 8.38 0.29 No 7 (2.5 ppm) VI.8 AlMg2.5 65/70 0.04 Nonionic Surfactant Antiscalant 1 0.03 0.00 No 7 (2.5 ppm) (4 ppm) VI.9 CuNi 75/80 0.02 w/o w/o 44.1 0.22 44.7 Yes 90/10 VI.10 CuNi 75/80 0.02 Nonionic Surfactant w/o 24.99 0.41 49.2 No 90/10 7 (2.5 ppm) VI.11 CuNi 75/80 0.02 Nonionic Surfactant 6 w/o 25.73 0.41 50.2 No 90/10 (2.5 ppm) & Nonionic Surfactant 12 (0.27 ppm) VI.12 CuNi 75/80 0.04 w/o w/o 5.6 0.16 1 No 90/10- PT VI.13 CuNi 75/80 0.04 Nonionic Surfactant w/o 3.1 0.16 7.6 No 90/10- 7 (2.5 ppm) PT VI.14 Al brass 65/70 0.02 w/o w/o 30.9 0.16 30 Yes VI.15 Al brass 65/70 0.02 w/o Antiscalant 1 0.04 0.07 NA No (4 ppm) VI.16 Al brass 65/70 0.02 Nonionic Surfactant w/o 1.91 0.06 NA No 7 (2.5 ppm) VI.17 Al brass 65/70 0.02 Nonionic Surfactant Antiscalant 1 0.01 0.06 NA No 7 (2.5 ppm) (4 ppm) VI.18 AlMg2.5 65/70 0.02 Nonionic Surfactant Antiscalant 1 0.04 0.00 NA No 7 (1.5 ppm) (3 ppm) VI.19 AlMg2.5 75/80 0.02 Nonionic Surfactant Antiscalant 1 0.37 0.09 NA No 7 (1.5 ppm) (4 ppm) VI.20 Al brass 65/70 0.02 Nonionic Surfactant Antiscalant 1 0.1 0.03 NA No 7 (1.5 ppm) (3 ppm) VI.21 Al brass 75/80 0.02 Nonionic Surfactant Antiscalant 1 0.03 0.07 NA No 7 (1.5 ppm) (4 ppm) = wetting rate; t.sub.EV = Evaporation temperature; t.sub.CO = Condensation temperature