Hydrocarbon Processing - July 2022 - 52

Process Optimization
2017, a study was carried out to establish
the company's capabilities for this goal.
The scope of the study covered DHT
units at both the MAA and Mina Abdullah
(MAB) refineries.
The units can achieve the required
CFPP limit with dewaxing and CFPP
additives. However, the study did not
elaborate on the specific requirements of
feed and product needed for the additive
to be effective. Furthermore, the study
concluded that the additive's vendors
will be the final entity in determining the
quantity required to achieve the desired
final specification. The study utilized
kinetic programs to estimate the requirement
for both DHT units at the MAA
and MAB refineries, based on estimated
unit design parameters.
The following crucial details were essential
for chemical selection:
* Feed and product specific
parameters and the distillation
range required for the
additives to be effective
* The feed blend and difficulty
to meet the specific gravity
limit in accordance with
the EN590 standard
* The expected properties of the
TABLE 3. KNPC DHT and gasoil desulfurization units (CFPP equals CP -2°C;
an upgrade in CP means an upgrade in CFPP)
Unit
DHT (MAA refinery)
DHT (MAB refinery)
New gasoil desulfurization
unit (MAA refinery)
∆ CP, °C
6
6
6
TABLE 4. DHT and gasoil desulfurization units' feeds
Unit stream
DCU diesel
Pour point, °C*
2
ARD distillate 1
ARD distillate 2
CDU light diesel
EOC light diesel
-14
-12
-12
-51
CFPP, °C
-14
-14
-14
Cold flow additives
No
No
No
individual feed streams to the
MAA refinery's DHT units
* Required additives
* Approval requirements
for the additives
* Information about the type
of additive (not limited to
WASAs, MDFIs and WAFIs)
* A clear representation of
economics (inclusive of the
requirement details for kerosene
to achieve final specifications).
Previously, KNPC had designed CFP
units to meet a mild cold properties specification
that was achievable, as tabulated
in TABLE 3. The challenge was the ability
to produce diesel with 10 ppm sulfur and
adhering to a CFPP limit of -22°C. The
study concluded that the MAA refinery
has different options, including revamping
the DHT unit, operating the dewaxing
bed or testing a specialized chemical additive-or
a combination of these options.
The CFP units have been designed for
CP, °C
4
-7
-10
-6
-51
TABLE 5. DHT and gasoil desulfurization feed properties
Properties
Specific gravity at
15°C (60°F)
Nitrogen, ppm
Sulfur, wt%
Monoaromatics, wt%
Diaromatics, wt%
Triaromatics, wt%
Total aromatics
Distillation
Start, °C
5°C
10°C
30°C
50°C
70°C
90°C
95°C
98°C
Coker diesel
0.882
930
0.54
20
15
5
40
D86 lv%
263
283
290
303
312
322
338
345
353
52 JULY 2022 | HydrocarbonProcessing.com
815
0.095
45
9
54
D86 lv%
189 (initial boiling point)
214
229
268
292
311
334
345
350 (end boiling point)
CFPP, °C
2
-8
-12
-8
-44
a 6-pt CP upgrade. To comply with the
CFPP requirements as per EN590 Euro 5
diesel, a further 6-pt upgrade by means of
cold flow improvers is required. The primary
challenge is to investigate the consequences
on the CFP units. The study provides
insights on the capability of the CFP
units' diesel product to either achieve a
CFPP of -20°C (base case Euro 5 specification)
or -22°C (stringent specification)
Old ARD diesel
0.863
CFP ARD diesel
0.8632
350
0.055
45
9
54
D86 lv%
181 (initial boiling point)
203
210
245
271
296
337
345
371 (end boiling point)
CDU light diesel
0.851
85
1.6
11.1
5.7
1.4
18.2
D86 lv%
186
243
259
273
286
304
335
345
362
EOC light diesel
0.8607
75
1.61
18.8
6.1
1
25.9
D86 lv%
172 (initial boiling point)
206
214
238
261
287
320
334
352 (end boiling point)
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