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INVESTIGATION ON DIESEL COLD FLOW PROPERTIES

1R.Dinkov*, 1D. Stratiev, 1D. Penev, 2G. Cholakov

1Chief Process Engineer Department., Lukoil Neftochim Bourgas JLC, Bulgaria,

*e-mail:dinkov.rosen.k@neftochim.bg

2University of Chemical Technology and Metallurgy – Sofia, Bulgaria,

Abstract: Cloud point (CP) and cold filter plugging point (CFPP) of 20 diesel range boiling fractions from different origin (both straight run and conversion effluents) were tested respectively by EN ISO 3015 and EN 116. Their values were calculated by using Khan’s formula and CP was also calculated by means of a commercial process simulator. The accuracy of the calculations was evaluated via absolute deviation (AD) and average absolute deviation (AAD). The latter was found to surpass the reproducibility of the test methods for the calculated data with the published in the open literature formulae with 14 0C for CP and with 13 0C for CFPP.

This difference between simulator calculated and experimental data AAD is 4 0C.

This fact encourages us to analyze our data and as a result simple and versatile correlations for CP and CFPP were derived from diesel fractions bulk properties (density and distillation).

Key words: Cloud point; Cold filter plug in point; Individual fractions; Blending

1. Introduction

A major problem for both refiners and users of diesel fuel or home heating oil is the behaviour of such fuels in cold weather. These products always contain varying amounts of n-alkanes. As ambient temperature decreases, the solubility of n-alkanes also decreases. Precipitation occurs over a wide temperature range, until solidification occurs. This limits the use of petroleum products. Dilution with kerosene, cutting the end boiling point of diesel fractions or addition of flow improvers is needed to meet the requirements of the various specifications and seasons [1]. The cold flow properties are important also from economical point of view.Even though there may be more diesel boiling range material in a specific crude oil or crude oil blend, cold flow properties can limit the amount that can be recovered [2].

The cold flow properties of diesel fuels are controlled by tree parameters:

 Cloudpoint (CP) is the temperature at which crystals first appear.

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 Pour point (PP). As the temperature gets colder, crystal growth continues and a lattice is obtained leading to solidification at the pour point.

 Coldfilter plugging point (CFPP). CP and PP cannot be directly correlated to the phenomenon leading to the plugging of diesel vehicle filters by n-alkane crystals, so a third parameter is used, the cold filter plugging point, which corresponds to the plugging of a 45pm filter under standardized conditions.

The best way to deal with this problem is to predict its occurrence and act preventively [3]. Because CP and CFPP aren’t additive properties a lot of researchers have tried to derive accurate correlations. Several correlation and graphical methods exists for calculating diesel blend cold flow properties from known components value.

These procedures are either specific in their use or valid for only a limited number of blending components [4].

2. Experimental data

Twenty diesel fractions from different technological processes (atmospheric and vacuum distillation, MHCU, FCC, HDS and VBU) were used for this study.

In order to evaluate the accuracy of Khan’s and simulator’s formulas for calculation of CP and CFPP for the available diesel fractions, the following physicochemical properties were determined: specific gravity by EN ISO 3675; distillation – both according EN ISO 3405 and ASTM D 2887 (presented in table I); n-alkanes distribution – data obtained from ASTM D 2887 (table II).

The fractions were tested for CP according to the procedure described in EN ISO 3015. The test precision for distillate oils is: repeatability – 2 0C and reproducibility – 4 0C. CFPP was analyzed by EN 116 with the precision:

repeatability – 1.76 0C and reproducibility – calculated with the following expression:

X) - (25

* 0.102 ility

Reproducib  (1)

(3)

Table I. SG and distillation of the investigated diesel fractions

21.12.2010 23.12.2010 10.01.2011

feed effluent feed effluent DF SRVD HSRD SRVD DF feed effluent DF DF HSRD SRVD effluent effluent DF mixture LCO

Property HDS 1 HDS 1 HDS 5 HDS 5 MHCU VDU 2 ADU 1 VDU 1 VBU HDS 5 HDS 5 MHCU VBU ADU 1 VDU 2 HDS 1 HDS 5 Tank

37 1 FCC

Specific gravity 0.8015 0.8012 0.8498 0.8384 0.8681 0.8704 0.8512 0.8987 0.8317 0.8493 0.8366 0.8684 0.8376 0.8555 0.8784 0.8006 0.8415 0.8336 0.8302 0.9412

Distillation

ASTM D 2887

IBP 101 115 38 111 139 172 104 210 81 56 101 143 90 115 179 113 111 116 114 134

5 150 152 162 181 167 217 221 282 168 164 172 171 178 231 228 150 182 171 168 181

10 166 166 197 205 190 236 248 309 179 192 192 195 194 254 248 168 210 188 185 201

20 178 179 232 234 225 262 263 336 195 220 216 228 208 271 268 182 238 211 206 220

30 189 190 255 255 251 279 274 354 211 245 235 255 221 283 282 192 255 230 224 230

40 197 197 271 270 272 294 287 368 224 263 255 278 236 296 295 197 270 249 240 234

50 208 208 287 286 293 305 301 381 238 279 272 298 252 308 305 206 285 267 258 250

60 216 216 302 301 310 317 314 392 253 297 291 315 266 320 316 215 300 286 278 255

70 226 225 317 316 326 329 327 404 269 315 310 331 283 334 327 220 314 305 299 266

80 235 235 335 332 344 343 343 419 287 335 330 349 303 351 340 229 330 327 319 276

90 243 243 357 356 365 359 362 438 313 360 357 369 331 370 357 237 354 354 346 289

95 250 250 372 371 380 373 376 454 334 379 376 384 356 384 372 245 368 372 365 300

FBP 260 260 408 408 412 413 410 496 399 412 413 416 433 419 415 257 400 413 402 327

ASTM D 86

IBP 156 162 153 183 184 222 205 278 157 156 172 188 169 213 231 162 186 174 172 189

5 176 177 204 212 196 242 254 311 188 198 200 201 203 260 254 179 218 196 193 210

10 183 183 220 226 213 255 263 326 197 213 212 218 211 269 264 185 231 207 204 219

20 190 190 243 246 238 272 272 345 208 234 229 242 220 280 277 192 248 224 218 229

30 195 195 259 259 256 282 280 356 217 249 242 260 228 288 286 196 260 237 230 235

50 206 206 282 281 288 300 296 374 234 274 268 293 248 303 300 203 280 262 254 246

70 216 216 305 303 312 316 315 388 260 303 298 317 274 322 314 212 302 294 288 255

80 222 222 318 316 327 324 325 396 272 320 315 332 287 333 321 217 314 312 305 261

90 227 227 336 335 343 337 340 412 297 340 337 347 314 348 336 222 333 334 327 271

FBP 242 242 362 361 366 362 364 435 341 368 367 371 366 371 363 239 356 265 358 293

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Table II. n-Alkanes distribution according to ASTM D 2887

21.12.2010 23.12.2010 10.01.2011

feed effluent feed effluent DF SRVD HSRD SRVD DF feed effluent DF DF HSRD SRVD effluent effluent DF mixture LCO

Property

HDS 1 HDS 1

HDS

5 HDS 5 MHCU VDU

2

ADU 1

VDU

1 VBU

HDS

5 HDS 5 MHCU VBU ADU

1

VDU

2 HDS 1 HDS 5 Tank

37 1 FCC

n-Alkanes, % (m/m)

C5 0.010 0.010 0.260 0.030 0.010 0.010 0.120 - 0.250 0.400 0.100 - 0.200 0.050 - - 0.004 0.003 0.003 -

C6 0.030 0.000 0.510 0.070 0.000 0.000 0.080 - 0.200 0.400 - - 0.180 0.080 - - 0.000 0.000 0.000 0.001

C7 0.240 0.100 0.200 0.060 0.000 0.000 0.100 - 0.120 0.120 0.080 - 0.100 0.080 - 0.008 0.009 0.008 0.010 0.000 C8 0.400 0.350 0.150 0.140 0.020 0.000 0.090 - 0.180 0.140 0.140 0.020 0.090 0.070 - 0.026 0.008 0.010 0.014 0.001 C9 0.970 0.010 0.270 0.260 0.440 0.020 0.120 - 0.220 0.290 0.360 0.330 0.160 0.100 0.020 0.053 0.019 0.026 0.030 0.002 C10 4.050 3.940 0.370 0.430 0.870 0.080 0.150 0.010 1.200 0.520 0.730 0.820 0.440 0.140 0.050 0.171 0.030 0.075 0.081 0.032 C11 4.610 4.740 0.670 0.630 0.510 0.250 0.210 0.030 1.650 1.130 1.290 0.490 1.570 0.160 0.150 0.311 0.031 0.107 0.125 0.097 C12 3.630 3.540 0.490 0.310 0.300 0.340 0.240 0.020 1.120 0.830 0.830 0.290 1.070 0.190 0.190 0.214 0.023 0.079 0.089 0.072 C13 3.510 3.540 0.630 0.610 0.580 0.490 0.460 0.010 0.800 0.990 1.410 0.480 1.130 0.360 0.360 0.178 0.059 0.079 0.089 0.174 C14 1.250 1.480 1.040 1.170 0.320 0.700 1.540 0.040 0.910 0.970 1.110 0.260 0.810 0.870 0.580 0.038 0.092 0.082 0.077 0.383 C15 0.020 0.020 1.450 1.710 0.390 0.990 2.130 0.050 0.630 1.200 1.350 0.150 0.650 1.610 0.810 0.001 0.117 0.079 0.075 0.169 C16 - - 1.590 1.620 0.420 1.080 1.940 0.130 0.720 1.020 1.240 0.320 0.930 1.760 1.160 - 0.100 0.073 0.068 0.056 C17 - - 1.880 2.150 0.960 1.730 2.550 0.260 0.670 1.530 1.600 0.740 0.610 2.390 1.560 - 0.143 0.106 0.097 0.000 C18 - - 1.580 1.770 0.850 1.700 2.130 0.480 0.410 1.310 1.320 0.840 0.580 2.090 1.740 - 0.124 0.082 0.080 0.005 C19 - - 1.270 1.300 0.860 1.480 1.580 0.640 0.240 0.940 0.960 0.600 0.340 1.600 1.260 - 0.086 0.061 0.056 0.003 C20 - - 0.810 0.890 0.690 1.000 1.180 0.600 0.140 0.710 0.750 0.630 0.230 1.070 0.660 - 0.054 0.049 0.038 0.002 C21 - - 0.490 0.550 0.510 0.510 0.710 0.640 0.060 0.420 0.420 0.480 0.140 0.690 0.360 - 0.040 0.024 0.026 0.001 C22 - - 0.390 0.450 0.380 0.340 0.570 0.860 0.040 0.350 0.330 0.450 0.070 0.520 0.250 - 0.030 0.023 0.021 - C23 - - 0.260 0.310 0.340 0.210 0.350 0.940 0.030 0.270 0.290 0.350 0.060 0.370 0.150 - 0.019 0.017 0.013 - C24 - - 0.130 0.150 0.190 0.090 0.180 1.060 0.020 0.170 0.180 0.180 0.030 0.220 0.070 - 0.009 0.010 0.006 - C25 - - 0.060 0.080 0.110 0.050 0.080 0.850 0.010 0.090 0.090 0.080 0.020 0.100 0.030 - 0.002 0.005 0.002 - C26 - - 0.020 0.030 0.030 0.020 0.020 0.660 - 0.030 0.050 0.050 0.020 0.040 0.020 - 0.001 0.002 0.001 -

C27 - - 0.010 0.010 0.010 0.010 0.010 0.420 - 0.010 0.010 0.010 0.010 0.010 0.010 - - 0.001 - -

C28 - - - - - - - 0.240 - - - - - - - - - - - -

C29 - - - - - - - 0.150 - - - - - - - - - - - -

C30 - - - - - - - 0.090 - - - - - - - - - - - -

Wax (C23+) content, % (m/m) 0.00 0.00 0.48 0.58 0.68 0.38 0.64 4.41 0.06 0.57 0.62 0.67 0.14 0.74 0.28 0.00 0.41 0.49 0.31 0.00 Total n-Alkanes, % (m/m) 18.72 17.73 14.53 14.73 8.79 11.10 16.54 8.18 9.62 13.84 14.64 7.57 9.44 14.57 9.43 17.23 13.05 14.52 14.36 8.74 Carbon Chain length 11.33 11.55 15.64 16.39 16.35 17.25 16.85 22.54 12.90 15.11 15.43 16.52 13.76 17.22 17.27 11.30 16.25 15.02 14.58 13.57

(5)

3. Results and discussion

Khan’s formulas were published in [4]. He derived very complex correlations with the following forms:

Where:

CP = cloud point, 0K

CFPP = cold filter plugging point, 0K

X1 = mid boiling point (T50), 0C;

X2 = wax (C23+) content, % (m/m);

X3 = total n-alkanes content, % (m/m);

X4 = carbon chain length

The required values for properties from X1 to X2 are presented in tables I and II. The AAD for CP calculated values by Khan’s correlation is 18 0C - table III. This value is with 14 0C greater than the reproducibility of the test method. This determines the correlation (2) inappropriate for calculating CP of the diesel fractions with properties, presented in tables I and II.

4 3 2 1 2

2 2

1 4

3 1 3

2 1

4 2 1 4

3 4

1 3

1 3

2

2 1 4

3 2

1

X X X 0,000127X +

0,100755X +

0,003523X +

X X 0,003485X +

X X 0,00574X -

X X 0,00578X -

X 0,62369X -

X 0,29151X -

X 0,05472X -

X 0,90767X +

X X 0,218171 +

78,37788X +

9,544403X +

30,7309X -

2,903971X +

-760,716 CP 

(2)

4 3 2 1 4

3 1 3

2 1 4

2 1 2

2

2 1 4

3 4

1 3

1 3

2

2 1 4

3 2

1

X X X 0,000123X +

X X 0,00521X -

X X 0,00339X -

X X 0,00346X -

0,002504X -

0,002504X +

X 1,823608X +

X 0,15842X -

X 0,105553X +

X 0,090358X +

X 0,143639X +

37,8724X +

33,8871X -

15,326X -

0,835709X +

-91,5312 CFPP 

(3)

(6)

Table III. Cold flow properties – calculated and measured

21.12.2010 23.12.2010 10.01.2011

feed effluent feed effluent DF SRVD HSRD SRVD DF feed effluent DF DF HSRD SRVD effluent effluent DF mixture LCO AAD Reproducibility

Property

HDS 1 HDS 1

HDS

5 HDS 5 MHCU VDU

2

ADU 1

VDU 1 VBU

HDS

5 HDS 5 MHCU VBU ADU

1

VDU

2 HDS 1 HDS 5 Tank

37 1 FCC

CP, 0C (measured) -51 -51 -6 -5 -3 -6 -2 25 -23 -6 -4 -2 -16 0 -4 -52 -7 -7 -10 -40

СFPP, 0C (measured) -51 -51 -7 -6 -4 -6 -3 - -27 -7 -6 -3 -20 -1 -7 - - - - -

CP, 0C (simulator) -47 -47 -15 -15 -17 -9 -6 18 -33 -10 -20 -14 -27 -3 -7 -48 -14 -21 -24 -37

CP, 0C (Khan) -91 -86 3 4 6 4 6 -104 -38 -1 -2 7 -20 6 3 -93 3 -6 -13 -22

СFPP, 0C (Khan) -95 -87 -13 -14 -22 -27 -12 -125 -35 -14 -14 -26 -26 -18 -32 -93 -17 -17 -21 -27

AD/CPsim, 0C 4 4 9 10 14 3 4 7 10 4 16 12 11 3 3 4 7 14 14 3 8 4

AD/CPKhan, 0C 40 35 9 9 9 10 8 129 15 5 2 9 4 6 7 41 10 1 3 18 18 4

AD/CFPPKhan, 0C 44 36 6 8 18 21 9 - 8 7 8 23 6 17 25 - - - - - 17 4

(7)

According to the data in table III and equation (1), the reproducibility of EN 116 for our data set is calculated as 4 0C.The AAD for CFPP calculated values by Khan’s correlation is 17 0C. This value is with 13 0C greater than the reproducibility of the test method. This determines the correlation (3) inappropriate for calculating CFPP of the shown diesel fractions.

Unsatisfactory result gives also the commercial process simulator ChemCad when calculating CP of diesel boiling range fractions from the data set. It uses the following equation:

Where:

CP = Cloud point of petroleum fraction, R;

MeABP = mean average boiling point, R;

SG = specific gravity, 60F/60F.

The AAD for CP is 8 0C, which is closer to the reproducibility but still isn’t within its range. The AAD for CP and CFPP are shown in table III. That’s why a decision was taken to evaluate the gathered in Lukoil’s refinery information about the diesel boiling fractions – both tables I and IV. The cold flow properties data is enlarged by different diesel boiling fractions, obtained from five types of crude oils (Libyan crude oil – Sirtica, Kuwaitian crude oil, REBCO, Heavy Iranian crude oil and Light Iranian crude oil). These fractions are produced by separation from the crude, performed according to ASTM D2892. The so obtained fractions are studied for distillation profile according to EN ISO 3405, specific gravity, CP and CFPP (table IV).

SG 0.133 - (MeABP) 0.712

- ) (MeABP log

5.49 + 7.41 -

= (CP)

log 0.315 (4)

(8)

Table IV. Cold flow and physical properties of straight run diesel fractions from different crude oils

Libyan crude oil - Sirtica Kuwaitian crude oil REBCO Heavy Iranian crude oil Light Iranian crude oil

Property

240- 370

240- 390

160- 370

160- 390

180- 375

220- 300

180- 375

300- 375

240- 375

220- 300

300- 375

180- 375

240- 375

220- 300

300- 375

180- 375

240- 375

220- 300

180- 375

240- 375 Specific gravity 0.8482 0.8483 0.8296 0.8298 0.8521 0.8260 0.8360 0.8530 0.8720 0.8374 0.8730 0.8418 0.8558 0.8377 0.8727 0.8444 0.8603 0.8340 0.8410 0.8590

Distillation

ASTM D 86

IBP 243 209 173 172 190 221 198 284 248 224 262 195 244 226 299 194 243 225 194 245

10 262 260 197 194 219 235 218 306 266 238 307 220 262 239 311 215 268 238 213 263

20 268 269 208 207 232 239 228 311 272 242 313 232 268 243 317 226 274 242 225 272

30 275 276 221 221 249 242 239 315 278 246 316 246 274 246 319 239 280 244 240 276

50 288 291 251 254 274 250 268 321 292 253 322 276 292 252 326 269 295 250 270 293

70 306 312 280 290 301 258 297 330 312 262 331 305 312 261 336 298 313 258 299 312

80 316 326 295 308 314 265 311 336 321 269 337 320 322 268 344 314 323 264 313 323

90 328 343 312 330 330 274 324 344 333 278 346 336 337 278 350 331 335 272 328 333

FBP 344 359 333 359 346 290 340 354 347 293 360 360 364 294 354 360 360 290 332 348

CP. 0C (measured) -2 1 -14 -7 -6 -25 -11 4 -3 -27 1 -10 -5 -24 9 -5 -1 -27 -10 0

СFPP. 0C (measured) 3 3 -16 -5 -5 -20 -9 7 -2 -27 5 -9 -1 -20 7 -6 -1 -20 -8 0

(9)

The data was analyzed by the integrated in Excel (Microsoft office package) correlation analyses tool. The result shows that the following parameters: T50, T90, T90- 20, T50*T90, SG and SG* T90 correlates well with the CP of the studied fractions. After that Excel regression was applied to the above (most appropriate) parameters, the following equation was derived.

Where:

T50 = temperature at which boils 50 % (v/v) according to ASTM D 86, 0C;

T90 = temperature at which boils 90 % (v/v) according to ASTM D 86, 0C;

T90-20 = difference in temperatures of 90 % (v/v) and 20 % (v/v) boiling from the fraction;

SG = specific gravity

a, b, c, d, e, f, g, h = regression coefficients with the following values:

a = 40.5188082034628 b = 0.352055808730715 c = 0.0213385486437754 d = -0.11817892070543 e = -0.00116227648075031 f = -345.341766942041 g = 0.91964970145254

The maximum CP residual value, calculated by Excel’s regression analyses tool, among the studied 40 fractions is 4.19 0C for the broad fraction 180 – 3750C, derived from REBCO. AAD for the whole data is 1.54 0C, which is even within the repeatability of EN ISO 3015. It should be pointed that equation (5) was derived for conversion processes effluents, boiling in the diesel range and straight run diesel fractions and also from different type of crude oils and with different distillation range.

90 90

50 20 - 90 90

50 cT dT eT *T fSG gSG*T

bT a

=

CP       (5)

(10)

CFPP of the studied diesel fractions can be described by the following equation:

Where:

The parameters are the same as these in equation (5) but the regression coefficients have the meanings:

a = 1639.74142105029 b = 2.78518229261183 c = -4.54863132880978 d = -0.131872294283347 e = -0.00802540514795706 f = -2960.97360934179 g = 8.36085679109224

For the 34 diesel fractions from tables I and IV with measured CFPP, the maximum residual value from the regression derived equation (6) is 5.3 0C for fraction 160-390 from Sirtica. AAD for the above fractions is 2.17 0C, which is within the reproducibility of EN 116.

Equations (5) and (6) are simple and versatile. They are derived from diesel fractions bulk properties (SG and distillation). It can be seen from table I that the CP and CFPP of the hydrotreated fraction is equal or with 1 0C higher than the value of the parameter for the hydrotreater feed. In such a way the parameters SG and distillation of diesel fractions can be used not only for determining the maximum recovering of diesel boiling material in the atmospheric and vacuum distillation of crude oils, and conversion processes fractionation but can be used also for modelling the cold flow properties of a refinery diesel pool. Diesel yield is determined by the season requirement for cold flow properties, because usually there is great amount of diesel in a specific crude oil but the recovery depends on the required cold flow properties.

90 90

50 20 - 90 90

50 cT dT eT *T fSG gSG*T

bT a

=

CFPP       (6)

(11)

The derived correlations (5) and (6) were tested for two diesel fuels, which consists of definite quantities of hydrotreated diesel from different HDSUs.

The first diesel blend contains: 30 % (v/v) hydrotreated diesel from HDSUs 1 and 4;

20 % (v/v) from HDSU 2 and 50 % (v/v) from HDSU 3. It possesses the following physicochemical

properties: distillation (ASTM D 86) 20 % (v/v) = 228 0C, 50 % (v/v) = 263 0C, 90 % (v/v) = 323 0C, SG = 0.8405, CP = - 9 0C and CFPP = -10 0C. Applying equations (5) and (6) for the above blend we received the following results: CP = - 10.1 0C and CFPP = -10.6 0C. The AD for CP is 1.1 0C and for CFPP is 0.6 0C or these deviations are within the repeatability of the standards.

The second diesel blend contains: 45 % (v/v) hydrotreated diesel from HDSUs 1 and 4; 55 % (v/v) from HDSU 2. Diesel’s physicochemical properties are: distillation (ASTM D 86) 20 % (v/v) = 223 0C, 50 % (v/v) = 253 0C, 90 % (v/v) = 319 0C, SG = 0.8375, CP = - 11 0C and CFPP = -12 0C. Applying equations (5) and (6) for the above blend we received the following results: CP = - 12.3 0C and CFPP = -13.1 0C.

The AD for CP is 1.3 0C and for CFPP is 1.1 0C or these deviations are again within the repeatability of the standards.

Another task of this study is to evaluate the ability of published in the open literature correlations for determining the CP of blend when knowing only the CP of its constituents [3,4] and the distillation, and SG of the fraction isn’t known.

i index, n

1 i

vi

index = x CP

BlendCP

(7)

 

 

20

index = 0.00264151.8CP 492

CP  (8)

1.8 0.0026415 492 BlendCP

= BlendCP

index 0.05





 

(9)

(12)

Where:

CP = cloud point, 0C;

Xvi = volume part of the fraction in the blend;

CPindex = cloud point index, used in order to transform the non additive property CP into an indexes which blend linearly on a volume basis – equation (7).

We apply the above procedure for blends, containing different quantity of hydrotreated diesel from HDSU 1 with CP = - 51 0C, from HDSU 5 with CP = - 7 0C and a diesel fuel, produced according to EN 590 with CP = - 7 0C .

Blend

№ Components %, (v/v) CPmeasured,

0C

CP calc. by eq. (7),

(8) and (9), 0C AD, 0C

1 HDSU 1

HDSU 5

10

90 -8 -8.4 0.4

2 HDSU 1

HDSU 5

20

80 -9 -9.9 0.9

3 HDSU 1

HDSU 5

30

70 -11 -11.6 0.6

4 HDSU 1

HDSU 5

40

60 -13 -13.5 0.5

5 HDSU 1

HDSU 5

50

50 -15 -15.7 0.7

6 HDSU 1

HDSU 5

60

40 -19 -18.4 0.6

7 HDSU 1

HDSU 5

70

30 -23 -21.8 1.2

8

HDSU 1 HDSU 5 Diesel EN 590

25 55 20

-10 -10.7 0.7

(13)

Calculating the blend’s CP, by equations (7), (8) and (9), of our data shows that for these 8 blends the AD is within the repeatability of BDS EN ISO 3015.

Depending on the available data for a diesel fractions blend, one can use equations (5) and (6) for determining respectively CP and CFPP when SG and distillation of the blend is known. In case only CPs of the blend components are reported, equations (7), (8) and (9) should be used.

References

[1] Claudy, P., Letoffee, J., “Interactions between n-alkanes and cloud point-cold filter plugging point depressants in a diesel fuel. A thermodynamic study”, Fuel, volume 72, 1993

[2] Barletta, T.,” Crude unit revamp increases diesel yield”, PETROLEUM TECHNOLOGY QUARTERLY, issue Spring 2000.

[3]Coutinho, J.,Pauly, J., “A thermodynamic model to npredict wax formation in petroleum fluids”, Brazilian journal of chemical engineering, vol. 18, 2001 [4] Khan, K., U., “New correlation predicts predict diesel cold- flow properties accurately”, Oil and gas journal, 1994

[4] RPMS 2000. Refinery and Petrochemical Modelling System, User’s Manual, 1999 [5]Fundamentals of petroleum refining, Elsevier, 2010

References

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