Study of Main Solutes on Evaporation and Crystallization Processes of

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The Study of Main Solutes on Evaporation and Crystallization Processes of the Desulfurization Wastewater Droplet Zhengxing Liang, Xining Cheng, li Zhang, Zhongqing Yang, Jingyu Ran, and Lin Ding Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b00778 • Publication Date (Web): 27 Apr 2018 Downloaded from http://pubs.acs.org on April 27, 2018

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The Study of Main Solutes on Evaporation and Crystallization Processes of the Desulfurization Wastewater Droplet Zhengxing Liang1,2, Xining Cheng1,2, Li Zhang1,2*, Zhongqing Yang1,2*, Jingyu Ran1,2, Lin Ding1,2, 1. Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education of China, Chongqing University, Shapingba District, Chongqing, 400030, China 2. College of Power Engineering, Chongqing University, Shapingba District, Chongqing, 400030, China (*Corresponding Author: Telephone: +86-23-65103114; Fax: +86-23-65103114; E-mail: [email protected] (Li Zhang), [email protected] (Zhongqing Yang)) Abstract: In this study, the evaporation and crystallization processes of the desulfurization wastewater droplet with different concentrations of main solutes were analyzed by TGA and DSC methods. The drying crystals were scanned by a scanning electron microscope. The supersolubilities were measured by the laser intensity detecting method. A mathematic model was built to investigate the relationship between the evaporation and crystallization rates and the species and concentrations of the solutes. The results show that, compared SO42- with Cl-, the 1 ACS Paragon Plus Environment

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higher concentration of SO42- gives higher evaporation rate (4.75 min of 0.006 mol NaCl, 4.5 min 0.003 mol Na2SO4) and lower crystallization rate (2.2 min of 0.006 mol NaCl, 2.5 min of 0.003 mol Na2SO4). This is because the vapor pressure is higher and the supersolubility is lower when the concentration of SO42- is higher. Compared Mg2+ with Na+, the changing concentration hardly affects the evaporation rate, because of similar vapor pressure. The higher concentration of Mg2+ leads to higher crystallization rate (2.1 min of 0.003 mol MgCl2, 2.2 min of 0.006 mol NaCl) due to the lower supersolubility. In the measurements of Ca2+, Mg2+ and Na+, the evaporation durations (around 4.45 min) and crystallization durations (2 - 2.05 min) are almost the same because of the low concentration solutes. According to the SEM results, the crystallization rate order when adding different ions is > Ca > .

Keywords: Evaporation and Crystallization; Desulfurization Wastewater; Concentration of Main Solutes; Supersolubility; TGA and DSC; Electrolytes;

1 Introduction The wet scrubber technology has been the dominated method for the desulfurization of the flue gas in the coal-fired power plants. Notably, to 2014 in China, wet scrubber technology [1] had been used in the over 80 % of all the flue gas desulfurization projects, and in the USA, 69 % of the 108 coal-fired power plants in the USA will adopt the wet scrubber technology by 2025 [2]. The wastewater from the flue gas desulfurization (FGD) system in coal-fired power plants is an important source of the water pollution, because lots of chloride ions and many other heavy metal ions, like mercury (Hg), selenium (Se) and arsenic (As). These ions are difficult to be purified by the traditional chemical precipitation method.

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In order to deal with these problems, some studies [3] were focused on removing the heavy metal ions by adding different species of chemicals in the chemical precipitation process. However, it would increase the daily cost of the power plants and these studies did not mention how to separate the chloride ions. A new method, zero liquid discharge (ZLD), was designed by Shaw [4]. The desulfurization wastewater would be evaporated and concentrated in an evaporator, and then it would be sent to a crystallizer. In this system, lots of energy was provided to heat the wastewater in the evaporator. To save the additional energy, Ran and Zhang [5] introduced their new ZLD system based on Shaw’s design. In their system, the desulfurization wastewater was sprayed directly into the gas flue which was at the end section of the boiler. After full evaporation by the hot gas in the flue, the residual solid particles would be captured by the dust precipitator. Compared with traditional method, Ran and Zhang’s design also decreased the outlet gas temperature which increased the operating efficiency of the boiler. In the ZLD system, evaporation and crystallization processes are two most important parts. Therefore, it is meaningful and beneficial to investigate the evaporation and crystallization characteristics of the wastewater droplets. Up to now, some studies about the droplet evaporation have been reported. Ece and Ozturk [6] built a new model for the unsteady convective fuel droplet in the first stage when the droplet began to move. Kim et al [7] discussed the evaporation and atomization characteristics of the biodiesel droplets in the high pressure injection system. They measured the spray behavior with frozen images and found that DME spray were shorter than those of biodiesel and diesel sprays. Yang [8] studied the relationship between droplet and fine particle emissions during the limestone−gypsum wet flue gas desulfurization process. They found that the count percentages of micrometer droplets and number concentrations of corresponding fine particles increased, as a result of the increases in the superficial gas velocity,


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gas−liquid ratio, and desulfurization slurry concentration and the decrease in the gypsum size distribution in the desulfurization slurry. Ma et al [9] discussed the spray and evaporation characteristics of the n-pentanol-diesel blends in a constant volume chamber. The effects of the ratio of the fuels and the temperature of the ambient gas were investigated. Apart from the evaporation, some studies of the crystallization have been reported. In the crystallization process, nucleation and crystal growth are two significant processes. Landfester et al [10, 11] investigated the effect of the temperature of the solution and the concentration of the solutes on the nucleation process of a single miniemusion droplet with the TGA and DSC methods. Vazquez et al [12] monitored the growth of an evaporating NaCl droplet using infrared thermography. They found that different concentration of NaCl could lead to different sizes of the crystals. Babaee et al [13] studied the effects of the concentration of the solutes, the temperature and the pressure on the formation of the hydrate. A kinetic model about the crystallization rate in the system of argon+TBAB+SDS has been built. Furthermore, the supersolubility is an important factor which affecting the nucleation rate and crystal growth rate. Wang et al [14] studied the effects of the solubility and the metastable zone width on the crystallization of 3, 4-bis(3-nitrofurazan-4-yl) furoxan (DNTF) in ethanol + water. The modified Apelblat equation was adopted to correlate the experimental solubility data, and the correlation result showed perfect consistent with the experimental data. Sun et al [15] investigated the supersolubility of the aluminum sulfate to help analyze the crystallization in the pure water. For the evaporation and crystallization of the wastewater, a few studies have been reported. Liang et al [16] studied the evaporation and crystallization process of the desulfurization wastewater from the coal-fired power plants with the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) methods. They analyzed the effect of temperature and 4 ACS Paragon Plus Environment

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droplet size on the evaporation and crystallization processes. Also, with the same technique, they [17] investigated the effect of the solid particles in the gas flue on the evaporation and crystallization processes of the wastewater droplet. Particles of SiO2, CaCO3, Fe2O3, Fe3O4 and fly ash could increase the crystallization rate, but Al2O3 could inhibit the nucleation process. In the desulfurization wastewater, it contains different species of ions. In the process of the wastewater, the evaporation technique is often used to increase the solutes concentration before the wastewater is sprayed into the gas flue. The concentration of the solutes often changes in the wastewater. According to Ref. [18, 19], the change of the concentration and the species of the solutes would change the evaporation rate of the solution in the same operating condition. In addition, according to Ref. [20, 21], the change of the concentration and the species also would change the crystallization rates. In the wastewater, it is important to find the relationship between the species and concentrations of solutes and evaporation and crystallization characteristics. Different kinds of ions have different effects on the evaporation and crystallization processes. In the real applications, the concentration of the ions in the wastewater could be detected and the best spray strategy could be decided in terms of this relationship. However, rare studies about the effect of the solutes on the evaporation and crystallization characteristics of the wastewater have been reported. So, in this study, the effect of the concentration and the species of some main solutes on the evaporation and crystallization of the desulfurization wastewater droplet were investigated. The evaporation process of the droplet would be detected by the TGA method and the crystallization process would be measured by the DSC method. The relationship between the evaporation and crystallization rates and the species and the concentration of the solutes of the wastewater droplet would be discussed. Then, the residual crystals would be observed by the scanning electron 5 ACS Paragon Plus Environment

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microscope (SEM). A model of the relationship between solutes in inorganic and organic solution and the vapor pressure was built to study the evaporation characteristic of the wastewater droplet. To help investigate the crystallization rate, the supersolubility of the wastewater at different concentrations of some species of the main solutes, was measured by the laser intensity detecting method.

2 Experimental Methodology 2.1 Materials The desulfurization wastewater was obtained from a coal-fired power plant (LuoHuang coal-fired power plant, Chongqing, China). The wastewater was captured at the position between the desulfurization system and the wastewater treatment plant. The concentrations of some main ions in the wastewater are presented in Table 1. It was measured by an ion Chromatograph (DIONEX ICS - 500). The operating temperature was 30 ℃ and the suppression current was 124 mA. The flow rate of the eluent is 1 mL/min. Table 1. Concentrations of the main ions in the desulfurization wastewater Cl−

ion (mg/L)

S O 42 −

3615.7475 12782.175

Na+

296.436

K

+

139.197

M g 2+

C a 2+

4166.256

448.423

So, according to the species of ions in the Table 1, the chemical solutes which would be added into the wastewater were shown in Table 2. Table 2. The solutes added into the wastewater Solutes

Purity

NaCl

AR

Na2SO4

AR


Manufacturer Chengdu Kelong Chemical Reagent Factory, China Chongqing Chuandong Chemical Co.,Ltd, China

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CaCl2

AR

MgCl2

≥ 98%

Chongqing Chuandong Chemical Co.,Ltd, China Tianjin Guangfu Institute of Chemical Industry, China

2.2 Instruments and Methodology As shown in Fig. 1, the solution of the deionized water and some additives was put in the glass-made crystallizer upon a magnetic stirring apparatus (85-2A, Jintan Xinrui, Jiangsu, China). The magnetic rotor was placed in the solution. The temperature of the water outside the solution in the crystallizer was controlled by a thermostatic water bath (DZKW, Zhongxing, China).

A laser beam generated by the He-Ne laser (632 nm, 1.5 mw, GY-11, TUOPU

Instrument, Tianjin, China) went through the crystallizer and was received by the laser power meter (WGN-1, TUOPU Instrument, Tianjin, China).

Figure 1. Setup for measurements of the supersolubility 1 Laser power meter, 2 magnetic stirring apparatus, 3 Laser, 4 Magnetic rotor, 5 Crystallizer, 6 Thermostatic waterbath 7 ACS Paragon Plus Environment

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First, the laser and the laser power meter were open. The deionized water and additives were added into the crystallizer. Then, the magnetic rotor was stirring at the speed of 150 r/min. The temperature of the water from the bath kept increasing to 5 ℃ upon the point ensured that the solution was clarified. The solution was kept at this temperature for about 1 hour. Finally, the temperature of the solution was decreased by 2 ℃/min. The temperature was recorded when the value of the laser power meter changed greatly. The evaporation and crystallization experiment system was presented in Fig. 2. A liquid droplet of desulfurization wastewater with different solutes was extracted by a pipette (Top Pipette 0.1-2.5 µL, DragonLAB), and placed on the center of a zirconium oxide pot. The pot with the droplet was put into the Thermogravimetric Analyzer (NETZSCH STA 409 PC). Then the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements were conducted in the analyzer. In the TGA measurement, the instantaneous mass of the droplet would be measured the heat transfer rate per unit droplet’s weight loss (Q=(W (mw))/(m (mg)), where W is the heat transfer rate, m is the weight loss of the droplet) of the droplet during evaporation in DSC measurement. The droplet would be evaporated in the pure nitrogen atmosphere. After that, the dry solid crystals would be placed into the scanning electron microscope (VEGA3, TESCAN) and the surface of the crystals would be scanned.


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Pure N2

Pipette

computer Working support

TGA

SEM The solid crystals of the desulfurization wastewater

The droplet of the desulfurization wastewater with additives

Figure 2. The experimental system for the evaporation and crystallization characteristics of the wastewater droplet

2.3 Operating Strategy Because of the low ion concentration in the original wastewater, it was difficult to find the supersolubility. So, the ions, with the concentrations which were 10 times as those in Table 1, were added into the 50 mL deionized water and this solution could be as the basic solution. Then, the quantity of the additives and the basic solution was presented in Table 3. Table 3. The operating conditions for the supersolubility tests Mole quantity of additives

Quantity of basic solution

(mol)

(mL)

MgCl2

0.005

50

NaCl

0.01

50

Na2SO4

0.005

50

CaCl2

0.0005

50

MgCl2

0.0005

50

NaCl

0.001

50

Species of additives


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Table 4. The species and molar quantities of the additives Condition

Species

number

of additives

1

2

3

4

Case

1

of Case

2

of Case

3

of

Case

4

of

mole quantity mole quantity mole quantity mole quantity (mol)

(mol)

(mol)

(mol)

NaCl

0.006

0.004

0.002

0

Na2SO4

0

0.001

0.002

0.003

NaCl

0.006

0.004

0.002

0

MgCl2

0

0.001

0.002

0.003

NaCl

0.0006

0.0004

0.0002

0

CaCl2

0

0.0001

0.0002

0.0003

MgCl2

0.0003

0.0002

0.0001

0

CaCl2

0

0.0001

0.0002

0.0003

Some additives were added directly into 10 mL original wastewater from the coal-fired power plant. The species and the molar quantities of the additives were shown as Table 4.Then, 1.0 µL wastewater droplet with different additives shown in Table 1, would be evaporated in TGA from room temperature (26 ℃) to 150 ℃ at the temperature increasing rate of 35 ℃/min. The temperature would be maintained at 150 ℃ for 20 min. Each experiments were conducted for two times. In the data analysis of the TGA and DSC, the data was obtained every 0.05 min. In the evaporation measurements, the line was considered to be horizontal when the difference of two adjacent data points was less than 0.1 (%). In the DSC measurements, the line was considered to be horizontal when the difference of two adjacent data points was less than 0.01 (mw/mg).


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3 Analytical Methodology For the spherical liquid droplet, according to Ref. [16], the evaporation rate of the droplet without considering the Stefan flow could be presented as follow: = 4

("#$% − "' ), (1)

where r, , , +, ", are the radius of the droplet, the density of the multi-flow, the diffusion coefficient of the vapor, and the volume concentration of the vapor, respectively. The subscription surf and ∞, represent the surface region of the droplet and the far field of ambient air. Assuming the latent heat L is a constant, the concentration of the vapor at the surface of the droplet could be expressed by Clausius - Clapeyron equation: "#$% = = exp ( − 89 89 / /

01023

7

:

7

), (2)

where ;#$% , ; |

]

B ]

+R

wD w2 w

S + exp R− ] S + (

(wD w2 )h/] w

) . (11)

Z is the valence of ions. The subscript a and c mean the anion and the cation. and are the

adjustable parameters. = 1/2 ∑ is the ionic strength. Pitzer [25] fixed b= 1.2 and = 2.0. = G + > . is the Debye-Huckel constant above 298.15 K which could be expressed as following equations [26]: 13 ACS Paragon Plus Environment

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= 3.36901532 × 10 − 6.32100430 × 10 A + 2.26089488 ×

zLh

9Y

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.Y 9

− 1.25143986 × 10 ln A +

+ 1.92118597 × 10 A + 45.2586464/(680 − A), (12)

where T is the temperature. The only depends on the temperature.

From Eq. (10-12), the water activity (a) could be obtained. When the chemicals of the case 1 and 4 in Table 4 are dissolved into pure water at 298.15 K, the values of the water activity are shown in Table 5 according to the data of , and in Ref. [27].

Table 5. Water activity of the solutes disolved in 10 mL pure water Concentration

0.006 mol

0.003 mol

0.003 mol

0.00015

0.0015

0.003

NaCl

Na2SO4

MgCl2

mol

mol

mol

CaCl2

MgCl2

NaCl

0.9955

0.9556

0.9763

Water Activity

0.7729

0.8963

0.7326

Substituted Eq. (10) into Eq. (2), the equation could be rewritten as "#$% = = / / /

01023

/rs

01023

= exp[− R zzzy S {]exp (89 wx

For the pure water, the term exp (

7

89:,rs

− 89

7

7

:,rs

− 89

7

). (13)

) is fixed at fixed pressure and temperature.

"#$% changes mainly with the value of water activity.

During the evaporation, the concentration of the solutes continue to increase and the droplet begins to crystallize. The crystallization process consists of the nucleation process and the crystal growth process. The homogeneous nucleation rate of the droplet could be expressed as follow according to Arrhenius reaction velocity equation [27]: J = Aexp R−

S = Aexp(− Y£ h 9 h (NO ¤)] ) , (14)

∆

¡h ¢ ]


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where σ is interfacial tension, T is temperature, S is degree of supersaturation, v is the molecular volume, k is the Boltzmann constant and A is the frequent coefficient. The crystal growth rate could be expressed as follow according to crystallization diffusion-reaction theories [28]: ¦§¨ ¦©

= ª (^ − ^ ) (diffusion) , (15a)

and ¦§¨ ¦©

= ª% (^ − ^~« )% (reaction), (15b)

where yf is a mass transfer diffusion coefficient, yr is a rate constant for the surface reaction process, ci is solute concentration in the solution at the crystal-solution interface, ceq is equilibrium saturation concentration and r is the order of reaction.

4 Results and Discussion 4.1 Supersolubilites Results of supersolubilities are shown in Fig. 3 when different additives are added into 50 mL basic solution. In Fig. 3(a), molar quantities of additives are 0.005 mol MgCl2, 0.01 mol NaCl, and 0.005 mol Na2SO4. In order to compare the effect of Cl- with that of SO42-, the concentration of cations kept the same. Also, the concentration of anions kept the same when comparing Cl- with SO42-. The results show that, at the same temperature, the order of the

supersolubility is 0.005 mol Na2SO4 > 0.01 mol NaCl > 0.005 mol MgCl2. This means 0.005 mol

MgCl2 is easiest to crystallize from the solution. In Fig. 3(b), at the same temperature, the order

of the supersolubility is 0.001 mol NaCl > 0.0005 mol CaCl2 > 0.0005 mol MgCl2. Also, in order to compare the effect of cations, the concentration of anions kept the same. The supersolubility is 15 ACS Paragon Plus Environment

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really close to that of original wastewater because the concentration of the ions are relatively low. Ca2+ could react with SO42-, and the concentration of SO42- is relatively high in the original wastewater.

Figure 3. The supersolubilities of the pure desulfurization wastewater with different species and different concentrations of solutes 16 ACS Paragon Plus Environment

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4.2 Effects of SO42- and Cl- on Evaporation and Crystallization Processes of the Wastewater Droplet Fig. 4 shows the weight loss process of the wastewater droplet under condition 1 in Table 4. There are two periods in Fig. 4. The first one is the declining period, and the other one is the horizontal period. According to Ref [16], the time of the turning point between the declining period and the horizontal period is considered as the ending time of evaporation. Table 6 shows the specific times of the turning points. With the increase of the concentration of SO42-, the duration of the declining period is shorter. This means the evaporation rate of the wastewater droplet is higher when the concentration of SO42- is higher. This is because vapor pressure of Na2SO4 solution is higher than that of NaCl solution at the same temperature. According to Eq. (13), the vapor pressure changes with the concentration of solutes. Table 5 shows that, dissolved in 10 mL pure water, 0.006 mol NaCl ( : 0.7729) makes water evaporate slower than that of 0.003 mol Na2SO4 ( : 0.8963). Specially, Ref. [32] ran the experiments to obtain the vapor pressure of saturated Na2SO4 solution and that of saturated NaCl solution. When the temperature is ranging from 20 to 40 ℃, the experiment results showed that the vapor pressure of saturated Na2SO4 solution (2.87 mol/kg) is higher than that of saturated NaCl solution (6.44 mole/kg).


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Figure 4. The normalized weight loss of the wastewater droplet when adding NaCl and Na2SO4 Table 6. The evaporation crystallization durations of the wastewater droplet when adding NaCl and Na2SO4 The mole quantity of the

Evaporation

Begin time and

Crystallizaton

additives

duration

ending time of the

duration (min)

(min)

crystallization (min)

0.006molNaCl

4.75

4.4-6.6

2.2

0.004molNaCl+0.001molNa2SO4

4.7

4.4-6.65

2.25

0.002molNaCl+0.002molNa2SO4

4.55

4.3-6.6

2.3

0.003molNa2SO4

4.5

4.25-6.75

2.5

Fig. 5 shows the heat flow of the entire evaporation and crystallization processes of the desulfurization wastewater droplet under condition 1 in Table 4. According to Ref. [16], the time interval between the peak point and the turning point to the horizontal is considering as the crystallization period. Time intervals of different concentrations of Cl- and SO42-, are shown in 18 ACS Paragon Plus Environment

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Table 6. In terms of Table 6, with the increase of the concentration of SO42-, the time interval become longer. This demonstrates the higher crystallization rate of Cl- compared with SO42-.

Figure 5. DSC curves of the desulfurization wastewater droplet when adding NaCl and Na2SO4 According to Eq. (14) and Eq. (15), higher supersaturation (S) gives higher nucleation rate and higher concentration difference gives higher crystal growth rate. From Fig. 3(a), at the same temperature, the supersolubility of solution adding Na2SO4 is higher than that adding NaCl. This means the supersaturation (C=C0 (initial concentration) - Cs (supersolubility)) is higher for Cl-. So, it gives higher nucleation rate and less time interval for Cl- compared with SO42-. Fig. 6 demonstrates the surface morphology of the crystals of the drying desulfurization wastewater droplet under condition 1 in Table 4. In Fig. 6 (a), lots of cracks could be observed obviously. With the increase of the concentration of SO42-, the quantity of the cracks decreases. According to theory from Ref [16], this means the crystallization rate is decreased from (a) to (d) in Fig. 6. These observed results are in agreement with the DSC results. 19 ACS Paragon Plus Environment

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Figure 6. The SEM scanning results of the drying crystals of the wastewater droplet when adding Na2SO4 and NaCl (a) 0.006molNaCl, (b) 0.004molNaCl + 0.001mol Na2SO4, (c) 0.002molNaCl + 0.002mol Na2SO4, (d) 0.003mol Na2SO4

4.3 Effects of Mg2+ and Na+ on Evaporation and Crystallization Processes of the Wastewater Droplet Fig. 7 shows the weight loss process of the wastewater droplet under condition 2 in Table 4. Compared the turning point to the horizontal of MgCl2 with that of NaCl in Fig. 8, the times of the turning points are almost the same. The specific value of the turning points are presented in Table 7. These similar turning points mean that the evaporation rate of the wastewater with high concentration Mg2+ is close to that with high concentration Na+. This is because the vapor pressure of the NaCl solution is similar to that of MgCl2 solution at the same temperature. Table 5 shows that, in 10 mL pure water, 0.006 mol NaCl ( : 0.7729) makes water evaporate slightly faster than that of 0.003 mol MgCl2 ( : 0.7326). This means that the evaporation rate rarely 20 ACS Paragon Plus Environment

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changes. According to Ref. [32], the vapor pressure of saturated Na2SO4 solution is close to that of saturated MgSO4 solution in the temperature ranging from 20 to 40 ℃. Also, the data in Ref. [32] is fitting to an Antoine equation. The constants of the Antoine equation are given. By solving this equation, the vapor pressures are similar for saturated MgSO4 solution and saturated Na2SO4 solution from 20 to 70 ℃. And according to Eq. (1) and Eq. (2), the similar saturated vapor pressure leads to similar evaporation rate.

Figure 7. The normalized weight loss of the wastewater droplet when adding MgCl2 and NaCl Fig. 8 shows the heat flow of the entire evaporation and crystallization processes of the desulfurization wastewater droplet under condition 2 in Table 4. Specific time intervals of different concentration of Mg2+ and Na+ are shown in Table 7. With the increase of the concentration of MgCl2, the crystallization duration is slightly shorter. This means the crystallization rate of Mg2+ is higher than that of Na+. Also, in terms of Fig. 3(a), the


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supersolubility of MgCl2 is lower than that of NaCl at the same temperature. This gives higher crystallization rate of MgCl2 than that of NaCl according to Eq. (14) and Eq. (15). Table 7. The evaporation crystallization durations of the wastewater droplet when adding MgCl2 and NaCl The mole quantity of the

Evaporation

Begin time and

Crystallizaton

additives

duration

ending time of the

duration (min)

(min)


0.006molNaCl

4.75

4.4-6.6

2.2

0.004molNaCl+0.001molMgCl2

4.7

4.35-6.55

2.2

0.002molNaCl+0.02molMgCl2

4.7

4.35-6.5

2.15

0.003molMgCl2

4.75

4.4-6.5

2.1

Figure 8. DSC curves of the desulfurization wastewater droplet when adding MgCl2 and NaCl Fig. 9 demonstrates the surface morphology of the crystals of the drying desulfurization wastewater droplet under condition 2 in Table 4. The quantity of the cracks on the surface of the crystals is slightly increasing from (a) to (c) in Fig. 9. The quantities of the cracks in Fig. 9 (c) 22 ACS Paragon Plus Environment

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and in Fig. 9 (d) are almost the same. This results show the same tendency with the DSC results. Also, it indicates that the effect of Mg2+ is stronger than that of Na+, on improving crystallization rate.

Figure 9. The SEM scanning results of the drying crystals of the wastewater droplet when adding MgCl2 and NaCl (a) 0.006molNaCl, (b) 0.004molNaCl + 0.001molMgCl2, (c) 0.002molNaCl + 0.002molMgCl2, (d) 0.003molMgCl2

4.4 Effects of ions (Ca2+ and Mg2+) and ions (Ca2+ and Na+) on Evaporation and Crystallization Processes of the Wastewater Droplet Fig. 10 shows the weight loss process of the wastewater droplet under condition 3 in Table 4 and Fig. 11 shows the weight loss process of the wastewater droplet under condition 4 in Table 4. Table 8 and Table 9 shows the specific times of the turning points to the horizontal, of the lines in Fig. 10 and Fig. 11 respectively. The values of these times of the turning points are really 23 ACS Paragon Plus Environment

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close which means the change of the concentration of Ca2+, Mg2+ and Na+ has the same effect on the evaporation process of the wastewater droplet in the concentration shown in Table 4. According to Ref. [32], the vapor pressure of saturated CaCl2 solution is much smaller than that of NaCl solution and MgCl2 solution. This could leads to the lower evaporation rate when the concentration of Ca2+ is relatively high. However, the evaporation rates are similar when changing the concentration of the ions. This because the concentrations of Ca2+, Mg2+ and Na+ are relatively low in this measurement. In the original wastewater, the concentration of SO42- is high and it could react with Ca2+. So, the tests were conducted in the low concentration of Ca2+. In Table 5, the water activities of 0.00015 mol CaCl2 (0.9955), 0.0015 mol MgCl2 (0.9556) and 0.003 mol NaCl (0.9763) are really close. This also provides that the evaporation rates are similar and close to that of pure water in this lower concentration.

Figure 10. The normalized weight loss of the wastewater droplet when adding NaCl and CaCl2


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Figure 11. The normalized weight loss of the wastewater droplet when adding CaCl2 and MgCl2

Table 8. The evaporation crystallization durations of the wastewater droplet when adding NaCl and CaCl2 The mole quantity of the

Evaporation

Begin time and

Crystallizaton

additives

duration

ending time of the

duration (min)

(min)


0.0003molNaCl

4.45

4.3-6.3

2

0.0002molNaCl+0.00005mol

4.5

4.3-6.35

2.05

4.5

4.35-6.35

2

4.45

4.3-6.3

2

CaCl2 0.0001molNaCl+0.0001mol

CaCl2 0. 00015molCaCl2

Table 9. The evaporation crystallization durations of the wastewater droplet when adding CaCl2 25 ACS Paragon Plus Environment

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and MgCl2 The mole quantity of the

Evaporation

Begin time and

Crystallizaton

additives

duration

ending time of the

duration (min)

(min)


0.00015molMgCl2

4.45

4.3-6.3

2

0.0001molMgCl2+0.00005mol

4.45

4.3-6.3

2

4.45

4.25-6.3

2.05

4.45

4.3-6.35

2.05

CaCl2 0.00005molMgCl2+0.0001mol

CaCl2 0.00015molCaCl2

Fig. 12, 13 show the heat flow of the entire evaporation and crystallization processes of the desulfurization wastewater droplet under condition 3, 4, respectively, in Table 4. Specific time intervals of different concentration of Ca2+, Mg2+ and Na+ are shown in Table 8 and 9. According

to Fig. 3(b), the crystallization rate order when adding different ions is > Ca > . However, the difference of the supersolubilities is difficult to be observed because of the low ion concentration. According to Eq. (14) and Eq. (15), the difference of the crystallization rates is also small. So, in Table 8, the crystallization durations are also similar and in Table 9, the duration is only shorter for 0.05 min when concentration of Mg2+ is relatively higher.


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Figure 12. DSC curves of the desulfurization wastewater droplet when adding NaCl and CaCl2

Figure 13. DSC curves of the desulfurization wastewater droplet when adding CaCl2 and MgCl2


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Fig. 14 shows the SEM scanning results of the drying crystals of the wastewater droplet when adding CaCl2 and NaCl. The quantities of the cracks in (b), (c) and (d) in Fig. 14 are almost the same. In Fig. 14 (a), the quantity of cracks is slightly smaller and some granulated crystals could be observed on the surface. Fig. 15 shows the SEM scanning results of the drying crystals of the wastewater droplet when adding MgCl2 and CaCl2. The quantities of the cracks in Fig. 15 (c) and Fig. 15 (d) are almost the same. In Fig. 15 (a), the quantity of the cracks is obviously increasing.

Figure 14. The SEM scanning results of the drying crystals of the wastewater droplet when adding CaCl2 and NaCl (a) 0.0003mmolNaCl, (b) 0.0002mmolNaCl + 0.00005mmolCaCl2, (c) 0.0001mmolNaCl + 0.0001mmolCaCl2, (d) 0. 00015mmolCaCl2


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Figure 15. The SEM scanning results of the drying crystals of the wastewater droplet when adding MgCl2 and CaCl2 (a) 0.00015mmolMgCl2, (b) 0.0001mmolMgCl2 + 0.00005mmolCaCl2, (c) 0.00005mmolMgCl2 + 0.0001mmolCaCl2, (d) 0.00015mmolCaCl2

5 Conclusion In this study, measurements of the supersolubilities of the desulfurization wastewater from the coal-fired power plant with different concentrations of solutes were conducted by the laser intensity detecting method. Then, TGA and DSC methods were used to detect the evaporation and crystallization characteristics of the desulfurization wastewater droplet when changing the concentration of the solutes. After evaporation in TGA system, the drying crystals were sent into the scanning electron microscope (SEM) to help analyze the crystallization process.


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An analytical model of the vapor concentration was built to help investigate the evaporation and crystallization rates. The specific mathematic description of the vapor concentration was given for organic compounds and single electrolytes. It built the relationship between the evaporation and crystallization rates and the species and concentrations of the solutes. Compared SO42- with Cl-, the high concentration of SO42- gives higher evaporation rate (4.75 min for 0.006 mol NaCl and 4.5 min for 0.003 mol Na2SO4). The change of solute concentration only affects the vapor pressure. And, the vapor pressure is higher when the concentration of SO42- is relatively high. So, this gives the higher evaporation rate. However, during crystallization, the high concentration of SO42- leads to low crystallization rate (2.2 min for 0.006 mol NaCl and 2.5 min 0.003 mol Na2SO4) because the supersolubility of the Na2SO4 is obviously higher than that of NaCl in the supersolubility measurement. The higher supersolubility of Na2SO4 gives lower supersaturation (S) and lower concentration difference. This leads to the nucleation rate and crystal growth rate are both lower when the concentration of SO42- is relatively high. Also, the quantity of the cracks on the surface of drying crystals is relatively high when the concentration of Cl- is higher. Then, compared Mg2+ with Na+, the changing of the concentration does not change the evaporation rate (around 4.7 min) of the wastewater droplet. This is because the effects of the Mg2+ and Na+ on the change of the vapor pressure are almost the same. Furthermore, according to the supersolubility results, the supersolubility of MgCl2 is lower than NaCl. This gives the high crystallization rate (2.2 min for 0.006 mol NaCl and 2.1 min for 0.003 mol MgCl2) when the concentration of Mg2+ is relatively high. The crystallization duration change is not as large as the SO42- and Cl- test (0.3 min) and only 0.1 min changes from 0.006 mol NaCl to 0.003 mol MgCl2. From the supersolubility results, the supersolubility line of 0.01 mol NaCl is in the 30 ACS Paragon Plus Environment

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middle of those of 0.05 mol MgCl2 and 0.05 mol Na2SO4. This caused the difference of crystallization rates between Mg2+ and Na+ is smaller. Finally, the higher quantity of cracks on the surface of the high Mg2+ crystals also suggests this result. Finally, in the measurements of Ca2+, Mg2+ and Na+, the evaporation rates (around 4.45 min) changes little with the solute concentration, although the vapor pressure of high concentration of Ca2+ is much smaller than those of high concentrations of Mg2+ and Na+. This is because the low concentration of solutes was added into the wastewater. Ca2+ could react with SO42- which is in the condition of relatively high concentration in the original wastewater. According to the DSC

and SEM results, the crystallization rate order when adding different ions is > Ca > which agrees with the results of the supersolubility measurements. However, the change of

the crystallization rate is slight because the low concentration of solutes.

Acknowledgements The authors gratefully acknowledge the financial support from the Key Industrial Generic Technology Innovation Project of Chongqing (cstc2016zdcy-ztzx20006) and the Chong Qing Municipal Solid Waste Resource Utilization & Treatment Collaborative Innovation Center (No.shljzyh2017-004) for this work.

References 1. China Development Report on Desulfurization and Denitration Industries in 2014. China Environmental Protection Industry, 2015(12): 4-23. 2. USEPA, Steam Electric Power Generation Point Source Category: Final Detailed Study Report, United States Environmental Protection Agency, 2009; USEPA 821-R-09-008. 31 ACS Paragon Plus Environment

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

3. Shaw, W.A., Benefits of evaporating FGD purge water. Power, 2008. 152(3): 59. 4. Shaw, W.A., Fundamentals of Zero Liquid Discharge System Design. Power, 2011; 155(10): 56. 5. Ran J.Y., Zhang Z.R.; A method of Spraying Evaporation to Deal with Desulfurization Wastewater from Coal-fired Power Plants with Wet Scrubber Technologies. Chinese Patent. Authorization Number: ZL 201010179796.3 6. Ece M.C., Ozturk A.; Modelling unsteady convective heat transfer for fuel droplets. Energy Conversion and Management, 2007. 48(3):689-692. 7. Kim H.J., Park S.H., Suh H.K., Lee C.S.; Atomization and Evaporation Characteristics of Biodiesel and Dimethyl Ether Compared to Diesel Fuel in a High-PressureInjection System. Energy & Fuels, 2009. 23: 1734-1742. 8. Pan D., Wu H., Yang L.; Investigation of the Relationship between Droplet and Fine Particle Emissions during the Limestone−Gypsum Wet Flue Gas Desulfurization Process. Energy & Fuels, 2017. 31(6): 6472-6477. 9. Ma Y., Huang S., Huang R., Zhang Y. Xu S.; Spray and Evaporation Characteristics of nPentanol-Diesel Blends in a Constant Volume Chamber. Energy Conversion and Management. 2016. 130: 240-251 10. Montenegro, R., Antonietti M., Mastai Y., Landfester K., Crystallization in Miniemulsion Droplets. Journal of Physical Chemistry B, 2003; 107(21): 5088-5094. 11. Taden, A., Landfester K., Crystallization of Poly (Ethylene Oxide) Confined in Miniemulsion Droplets. Macromolecules, 2003. 36(11): 4037-4041. 32 ACS Paragon Plus Environment

Page 32 of 37

Page 33 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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12. Vazquez, P., Thomachot-Schneider C., Mouhoubi K., Fronteau G., Gommeaux M., Benavente D., Barbin V., Bodnar J.L.; Infrared thermography monitoring of the NaCl crystallisation process. Infrared Physics & Technology, 2015. 71: 198-207. 13. Babaee S., Hashemi H., Mohammadi A.H., Naidoo P., Ramjugernath D.; Kinetic Study of Hydrate Formation for Argon + TBAB + SDS Aqueous Solution System. J. Chem. Thermodynamics. 2017. 116: 121-129 14. Chen L., Song L., Lan G., Wang J.; Solubility and Metastable Zone Width Measurement of 3,4-Bis(3-nitrofurazan-4-yl)Furoxan (DNTF) in Ethanol + Water. Chinese Journal of Chemical Engineering. 2017. 25: 646-651. 15. Sun X., Sun Y., Yu J.; Cooling Crystallization of Aluminum Sulfate in Pure Water. Journal of Crystal Growth. 2015. 419: 94-101. 16. Liang Z., Zhang L., Yang Z., Qiang T., Pu G., Ran J.; Evaporation and Crystallization of a Droplet of Desulfurization Wastewater from a Coal-Fired Power Plant. Applied Thermal Engineering. 2017. 119: 52-62 17. Liang Z., Zhang L., Yang Z., Cheng X., Pu G., Ran J.; The Effect of Solid Particles on the Evaporation and Crystallization Processes of the Desulfurization Wastewater Droplet. Applied Thermal Engineering. 2018. 134: 141-151. 18. Lin J.C., Gentry J.W.; Spray Drying Drop Morphology: Experimental Study. Aerosol Science and Technology. 2003. 37(1):15-32.


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

19. Taniguchi I., Inoue T., Asano K.; Evaporation of a Salt Water Drop with Crystallization. Atomization and Sprays. 1999. 9:69-85 20. Kim J.W., Shin M.S., Kim J.K., Kim H.S., Koo K.K.; Evaporation Crystallization of RDX by Utralsonic Spray. Industrial & Engineering Chemistry Research. 2011. 50(21):12186-12193. 21. Baldelli A., Power R.M., Miles R.E.H., Reid J.P., Vehring R.; Effect of Crystallization Kinetics on the Properties of Spray Dried Microparticles. Aerosol Science and Technology. 2016. 50(7):693-704. 22. Joback K.G., Reid R.C.; Estimation of Pure-Component Properties from GroupContributions. Chem. Eng. Comm. 1987. 57:233-243. 23. Ghasemitabar H., Movagharnejad K.; Estimation of the Normal Boiling Point of Organic Compounds via a New Group Contribution Method. Fluid Phase Equilibria. 2016. 411:13-23. 24. Boethling R.S., Mackay D.; Handbook of Property Estimation Methods for Chemicals, CRC Press, Boca Raton, FL, 2000. 25. Mansour K., Korichi M.; An Enhanced Group-Interaction Contribution Method for the Prediction of Normal Boiling and Critical Points. Proceedings of the 26th European Symposium on Computer Aided Process Engineering. 2016. 26. Bialik M., Sedin P., Theliander H.; Boiling Point Rise Calculations in Sodium Salt Solutions. Industrial & Engineering Chemistry Research. 2008 47:1283-1287. 27. Pitzer, K. S.; Thermodynamics of electrolytes. I. Theoretical basis and general equations. J. Phys. Chem. 1973, 77(2): 268–277. 34 ACS Paragon Plus Environment

Page 34 of 37

Page 35 of 37 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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28. Ge X., Wang X.; Estimation of Freezing Point Depression, Boiling Point Elevation, and Vaporization Enthalpies of Electrolyte Solutions. Industrial & Engineering Chemistry Research. 2009. 48: 2229-2235. 29. Kim H.T., Frederick J.W. Jr.; Evaluation of Pitzer Ion Interaction Parameters of Aqueous Electrolytes at 25.degree.C. 1. Single Salt Parameters. J. Chem. Eng. Data. 1988. 33: 177-184. 30. Mullin, J.W., 5 - Nucleation, Crystallization (Fourth Edition), Butterworth-Heinemann: Oxford. 2001, p. 181-215. 31. Mullin, J.W., 6 - Crystal Growth, Crystallization (Fourth Edition). Butterworth-Heinemann: Oxford. 2001, p. 216-288. 32. Leon-Hidalgo M.C., Gozalvez-Zafrilla J.M., Lora-Garcia J., Arnal-Arnal J.M.; Study of the Vapour Pressure of Saturated Salt Solutions and Their Influence on Evaporation rate at room Temperatue. Desalination and Water Treatment. 2009. 7(1-3): 111-118


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Appendix A Nomenclature A

Frequence coefficient

v

Molecular volume [nm3]

Debye-Huckel constant

y

Reaction diffusion coefficient

o

Water activity

a, b, c

Equation constant

C

Volume concentration of the vapor

"=

The contribution of the group

c

Solute concentration

Diffusion coefficient [cm2/s]

G

Activation energy [kJ/mol]

I

Ionic strength [mol/kg]

J

Nucleation rate [mg/s]

K

Total contribution of liquid

Subscript

k

The Boltzmann constant

a

Greek Symbols

α β γ

ρ

υ

ϕ σ


Fixed constant Adjustable parameter Adjustable parameter Density [g/m3] Stoichiometric coefficient

Osmotic coefficient interfacial tension [mN/m]

Anion

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L

Latent heat [kJ/mol]

b

Boiling

o

Molecular weight

c

Cation

m

Evaporation rate [mg/s]

eq

Equilibrium condition

m

Molality [mol/kg]

i

The ith phase

²

Diffusion mass [mg]

ion

Liquid containing ions

N

The number of the group

mix

The mixed phase

p

Pressure [Pa]

pure

Pure water

R

Universal constant

surf

Surface condition

r

Radius of the droplet [mm]

total

Total gas phase

S

Degree of supersaturation

∞

Far field of ambient air

T

Temperature [K]


Study of Main Solutes on Evaporation and Crystallization Processes of

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