diesel hydrotreaters revamp a way for increasing production

44th International Petroleum Conference, Bratislava, Slovak Republic, September 21-22, 2009 1
DIESEL HYDROTREATERS REVAMP A WAY FOR
INCREASING PRODUCTION OF NEAR ZERO SULPHUR
DIESEL AND IMPROVING THE ENERGY EFFICIENCY
Dicho Stratiev, Iliya Vergov, Todor Tzingov, Ivelina Shishkova
Lukoil Neftochim Bourgas- R&D Department, 8104 Bourgas, Bulgaria,
e-mail: stratiev.dicho@neftochim.bg
KEY WORDS: near zero sulphur diesel ,energy efficiency, hydrotreater revamp
ABSTACT
The progress of catalyst technologies allowed the diesel hydrotreating
units designed for production of diesel with sulphur content of 3 000 ppm to
accommodate production of automotive diesel with sulphur content of 500,
350, and 50 ppm without need of reconstruction. Even the 10 ppm sulphur
diesel was possible to produce only by a reduction of the content of the
refractory sulphur species boiling above 340 0 C from 30 to 15% in the diesel
hydrotreater feed. However, the dieselization of Europe requires higher volume
of automotive diesel production. To meet this challenge the Lukoil Neftochim
Bourgas has made a revamp of two of its four middle distillate hydrotreaters
which process heavy diesel fractions. The revamp consisted of a reduction of
the liquid hourly space velocity (LHSV) from 2.0 and 1.7 to 1.17 and 0.90 h -1 by
adding additional catalyst volume. In order to prevent the possibility of
leakage, observed two years ago, the heat exchangers utilizing the reactor
product heat were replaced. The unit revamp was performed within 20 days
and the project was executed (from the start of the basic design preparation to
the final unit reconstruction) within a year. The critical equipment – new
reactors were prepared within less than one year. The performance test
showed that the revamped hydrotreaters produce 8 ppm sulphur diesel at 10 0 C
lower than the design weight average bed temperature (WABT) from a
feedstock that contained 30% fraction boiling above 340 0 C. The saturation of
poly- to mono - nuclear aromatics was increased from 40 to 50% leading to
increase of hydrogen consumption by about 11%. The installation of the new
heat exchangers has resulted in 50% fuel savings.
INTRODUCTION
The near zero sulphur diesel(NZSD) had to be available at the petrol
station pump as from 01.01.2009 in the whole European union according to
Directive 2003/17/EC. The preparation for production of NZSD started in the
Lukoil Neftchim Bulgaria (LNB) refinery much earlier than the mandate date
[1]. However, the achieved improvement in the operation of the existing
middle distillate hydrotreaters was not enough to provide 100% production of
NZSD. The mandate date of 01.01.2009 was very close and a reconstruction
of the LNB heavy middle distillate hydrotreaters HDS-2 and HDS-3 seemed
difficult to implement starting in late 2007. Due to the higher load of the most
manifacturers of special equipment in 2008 the duration of manufacturing of
hydrotreating reactors would not be shorter than 18 months. This meant not
complying with the deadline for production of NZSD in the LNB. In order to

44th International Petroleum Conference, Bratislava, Slovak Republic, September 21-22, 2009 2
find a solution in this tough situation the technological department and the
research laboratory made estimation about the required catalyst volume
increase necessary to achieve production of NZSD in the hydrotreating units
HDS-2 and HDS-3 running on a mixture of heavy straight run gas oil and light
vacuum gas oil from Ural crude. This estimation showed that the liquid hourly
space velocity (LHSV) should be approximately 1.0h -1 if the mixture of heavy
straight run gas oil and light vacuum gas oil from Ural crude is hydrotreated at
a pressure of 35 kg/cm 2 on the Topsoe TK-576 Brim catalyst. This catalyst
proved to be among the best performers in the ultra low hydrodesulphurization
[1,2]. The LHSV of about 1.0h -1 was possible to achieve if reactors with
dimensions of the LNB FCC feed hydrotreating reactors were installed in the
HDS-2 and HDS-3 units. Drawings of these reactors were available and this
gave the opportunity to shorten the time for their manufacture. The LNB
signed a contract with the Haldor Topsoe (HTAS) for basic engineering of
reactor section for reconstruction of the LNB HDS-2 and HDS-3 units in
November 2007. In late November 2007 HTAS assured LNB that the LNB
FCC feed hydrotreating reactors fit the reconstruction of the HDS-2 and HDS-
3 units and LNB signed a contract for manifacturing of the hydrotreating
reactors for a period of less than 12 months with the Russian company OOO
Energomash-Atomash. Having the bitter experience with appearance of
leakage in the heat exchangers LNB was aware that the production of NZSD
could fail if the older heat exchangers were used [3]. That is why a contract
with the Ukrain company OOO Mashzavod was signed for manufacturing of
shell and tube heat exchangers for utilization of the energy of the reactor
product stream effluent. The delivery term for the heat exchangers was lower
than 12 months. With this tight schedule the HDS-3 was reconstructed and
successfully started up operation in late December 2008.The HDS-2 unit was
reconstructed and successfully started up operation in early March 2009. The
aim of this work is to discuss the achieved operation of the reconstructed LNB
heavy middle distillate hydrotreating HDS-2 and HDS-3 units.
EXPERIMENTAL
The performance test of the reconstructed LNB HDS-3 was carried out in
December 2008 at following conditions:
- Feedstock properties
Density at 15 °C, kg/m3 851.6-853.5
Distillation, ASTM D 86, o C
- IBP 208-220
- 10% vol% 257-265
- 50% vol% 294-300
- 90% vol% 330-340
- 95% vol% 338-349
- EBP 355-360
Sulfur , wt% 0.66-0.875
Bromine number, g Br2/100 g 0.9-2.8
Total aromatics,% 27.4-29.2
Polynuclear aromatics , % 8.8-9.7

44th International Petroleum Conference, Bratislava, Slovak Republic, September 21-22, 2009 3
- Unit operating conditions:
LHSV, h -1
0.90
First reactor inlet temperature, ºC 350
First reactor outlet temperature, ºC 362
Second reactor inlet temperature, ºC 360
Second reactor inlet temperature, ºC 362
Hydrogen/Oil ratio, Nm 3 /m 3 230
Hydrogen make-up, Nm 3 /m 3 66
Hydrogen content in the make up gas, mole% ≥ 80
The performance test of the reconstructed LNB HDS-2 was carried out in
March 2009 at following conditions:
- Feedstock properties
Density at 15 °C, kg/m3 854,6-860,9
Distillation, ASTM D 86, o C
- IBP 179-219
- 10% vol% 233-252
- 50% vol% 294-302
- 90% vol% 340-349
- 95% vol% 351-360
- EBP 360
Sulfur , wt% 0.983-1.12
Nitrogen , mg/kg 164 -266
Bromine number, g Br2/100 g 3.35 - 5.68
Total aromatics,% 29.6
Polynuclear aromatics , % 11.1
- Unit operating conditions:
LHSV, h -1
1.17
First reactor inlet temperature, ºC 349
First reactor outlet temperature, ºC 374
Second reactor inlet temperature, ºC 372
Second reactor inlet temperature, ºC 374
Hydrogen/Oil ratio, Nm 3 /m 3 284
Hydrogen make-up, Nm 3 /m 3 76
Quench, Nm 3 /m 3 10
Hydrogen content in the make up gas, mole% 79.5-86

44th International Petroleum Conference, Bratislava, Slovak Republic, September 21-22, 2009 4
RESULTS AND DISCUSSION
During the performance test of the HDS-3 unit the product (stable
hydrogenate) properties were as follows:
- Product properties
Sulphur , wt ppm ≤ 5
Density at 15 °C, kg/m 3 840.5-843.6
Polynuclear aromatics , % 4.6-5.8
These data indicate that the increase of the catalyst volume by a factor
of 1.9 (decreasing the LHSV from 1.7 to 0.90h -1 ) allowed the LNB heavy
middle distillate hydrotreater HDS-3 to produce NZSD. The hydrogen
consumption was found to be 28.3 Nm 3 /m 3 oil which was 8% higher than that
recorded before the reconstruction (26.3 Nm 3 /m 3 oil).
During the performance test of the HDS-2 unit the product (stable
hydrogenate) properties were as follows:
- Product properties
Sulphur , wt ppm ≤ 5
Density at 15 °C, kg/m 3 844-845
Polynuclear aromatics , % 4.6-5.8
These data indicate that the increase of the catalyst volume by a factor
of 1.7 (decreasing the LHSV from 2.0 to 1.17h -1 ) allowed the LNB heavy
middle distillate hydrotreater HDS-2 to produce NZSD. The hydrogen
consumption was found to be 34.2 Nm 3 /m 3 oil which was 14% higher than that
recorded before the reconstruction (30.1 Nm 3 /m 3 oil).
Figures 1 and 2 present the deactivation of the catalyst TK-576 Brim in
the LNB HDS-3 and HDS-2 heavy middle distillate hydrotreaters. It is evident
from these data that the catalyst in HDS-2 unit has exhibited higher
deactivation rate of 3.4 0 C/month, than HDS-3 catalyst whose deactivation rate
is 3.0 0 C/month. With a start of run temperature (SORT) of 350 0 C and end of
run temperature (EORT) of 390 0 C a cycle length of 13 months is obtained for
HDS-3. With a start of run temperature (SORT) of 349 0 C and end of run
temperature (EORT) of 390 0 C also a cycle length of 12 months is obtained for
HDS-2. The replacement of the older heat exchangers in both units not only
improved reliability but also improved the unit energy efficiency. The cost for
fuel gas was reduced by a factor of two.

O C
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44th International Petroleum Conference, Bratislava, Slovak Republic, September 21-22, 2009 5
WABTreal WABTnorm Product suphur
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
Days of Run
Figure 1 Deactivation of the catalyst TK-576 Brim in the LNB HDS-3 unit
Deactivation rate - 3.0 o C/month
50
45
40
35
30
25
20
15
10
5
0
Product sulphur, ppm

О С
400
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44th International Petroleum Conference, Bratislava, Slovak Republic, September 21-22, 2009 6
WABT real WABT norm Product sulphur
300
0
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Days of Run
Figure 2 Deactivation of the catalyst TK-576 Brim in the LNB HDS-2 unit
Deactivation Rate - 3.4 o C/month
50
45
40
35
30
25
20
15
10
5
Product sulphur, ppm

44th International Petroleum Conference, Bratislava, Slovak Republic, September 21-22, 2009 7
CONCLUSIONS
The design and construction of the revamp of the LNB heavy middle
distillate hydrotreating units HDS-2 and HDS-3 was implemented for a record
short time of 12 months due to the well organized and coordinated work
between the Lukoil Chief engineer department, the licensor of technology
Haldor Topsoe and the manufacturer of reactors and heat exchangers the
Russian company OOO Energomash-Atomash and the Ukrain company OOO
Mashzavod. The units were put on stream according to the planned schedule
and demonstrated stable operation with an expected catalyst cycle length of
12-13 months.
REFERENCE
[1] I. Vergov, I. Shishkova, “Catalyst advances promote production of near
zero sulphur diesel”, Petroleum & Coal, 51 (2), pp. 136-139, 2009.
[2] D. Stratiev, V. Galkin, K. Stanulov, “Study: Most-active catalyst
improves ULSD economics”, Oil&Gas Journal, Aug.14, pp. 53-56, 2006.
[3] D. Dobrev, D. Stratiev, T. Tzingov, G. Argirov, V. Dyakov, P. Petkov,
“Effect of unreliable diesel hydrodesulphurization unit equipment operation
on the production of ultra low sulphur diesel”, Proc. 43 th International
Petroleum Conference, 2007, Bratislava, Slovac Republic.