RB-22 ANALYSIS OF THE INFLUENCE OF THE TYPE OF FUEL OIL ON CORROSION AND
RESIDUES ON |
rb
bertomeu, S.L. |
Facility:
Power Plant at Minera de Santa Marta
(M.S.M.) Engines:
3 Deutz MWM engines, type BV 16M 640 Power
output:
3 x 6.3 MWhe Period
analysed: January
1997 to March 1999 (27 months) CONTENTS
CONCLUSIONS OF THE STUDY 1.
Brief preliminary history 2.
Data on fuel oils utilised and their treatment with additives 3.
Engine overhauls supervised by rb bertomeu S.L. 4.
Comparison of controlled parameters when using Fuel No. 1 BIA and
Fuel No. 1, both treated with additives from “rb
bertomeu” 4.1 Quantities
of incrusted residues on exhaust valves 4.2 Level of
replacement of exhaust valves CONCLUSIONS OF THE STUDY BASED ON HISTORICAL DATA FROM M.S.M. A - The first conclusion can be
drawn on the basis of historical data from M.S.M and the initial periods
since the engines went into operation, when only fuel oil No. 1 BIA was
used and TBO’s alternated between fuel treated with
additives from “rb bertomeu”
and untreated fuel. This first conclusion is that Fuel oil
No. 1 BIA causes corrosion on the exhaust valves and the accumulation of
residues on the valves themselves and on the turbos,
and that these effects are minimised when Fuel oil No. 1 BIA is regularly
treated with “rb bertomeu”
additives. Therefore, if the changeover is made to the
consumption of Fuel oil No. 1 BIA or the equivalent low-sulphur fuel
oil, problems of corrosion and residues will occur in the event of discontinuing
the treatment with additives from “rb bertomeu”. B - The changeover from Fuel
oil No. 1 BIA to Fuel oil No. 1 DID NOT PRODUCE SIGNIFICANT EFFECTS ON
THE RESIDUES ACCUMULATED ON EXHAUST VALVES, when both fuels were treated with
additives from “rb bertomeu”.
It is therefore logical to suppose that it had no effect on the accumulation
of residues on turbos and other areas of the
exhaust gas circuit that would lead to any change in the requirements of
cleaning. This last point is not included in our statistical data. C - The changeover from Fuel
oil No. 1 BIA to Fuel oil No. 1 DID HAVE MORE
SIGNIFICANT EFFECTS ON THE LIFE SPAN OF EXHAUST VALVES (an increase in
corrosion) AND CONSEQUENTLY ON THE LEVEL OF REPLACEMENT OF THESE
VALVES. There was an increase in the level of replacement of 67% for
valve baskets and 57% for valve cones, irrespective of the age of the valves. Given that exhaust valves were not replaced
in overhauls (they were rectified and reinstalled), the analysis of
the results must take into account that the period of consumption of Fuel oil
No. 1, when the level of replacement of valves is highest, corresponds
to valves with an average life span ranging from 24,000–25,000 hours up to
30,000–32,000 hours (more than double the theoretical operational life stated
by the manufacturer), whereas the period of consumption of Fuel oil
No. 1 BIA corresponds to ‘younger’ valves with an average life ranging
from 15,000 hours up to 24,000–25,000 hours. In all probability, the differences
in replacement would be less if it were possible to compare valves with the
same average life in operation, which would mean that all the valves would
have been subject to the same rectifications, thermal fatigue, etc. D – If the changeover is made
to consumption of Fuel-oil No. 1 BIA, as a substitute for the current
Fuel oil No. 1 and there is continued additive treatment with additives
from “rb bertomeu”,
it can be expected to produce the following effects: D-1 Levels similar to present levels are maintained in terms of
residues deposited in the exhaust gas circuit (exhaust valves, turbocompressors, etc.). D-2 A reduction may be obtained in the level of replacement of exhaust
valves of 40% (valve baskets) and 36% (valve cones) at the maximum in comparison
with the current level, if the Fuel oil BIA is at the current specification,
i.e., a relatively low content in vanadium and sodium. Probably the reduction
would be much lower (in the order of 15-20%), taking into account the effect
of the “age of the valves” described in “C”. D-3 The current level of replacement of exhaust valves is maintained
when using a type of new low-sulphur fuel oil that nevertheless contains
impurities in similar quantities to the current Fuel oil No. 1 or Fuel
oil No. 2 (fundamentally vanadium and sodium). **************************** 1. BRIEF PRELIMINARY HISTORY The three engines were started up in 1995.
For the first 3,000 hours they ran on Fuel No. 1 BIA without
additives. Following the overhaul at 3,000 hours on engines 1, 2 and 3 (August
1995), on observing that corrosion had appeared on exhaust valves, MSM
decided to treat the Fuel oil No. 1 BIA with additives from “rb bertomeu”. The type
employed was beco FB, the formula
specified for Fuel No. 1 BIA at that time, and the additive treatment
commenced in August 1995. Following the overhaul at 4,500 hours on engines 1, 2 and 3 (October
1995), it was observed that the corrosion on exhaust valves had almost
disappeared. For this reason MSM decided to suspend the additive
treatment of Fuel oil No. 1 BIA in order to verify the actual effect of
the additive “rb bertomeu”.
The additive treatment was discontinued in October 1995. At the subsequent overhaul, at 6,000 hours on engines 1, 2 and 3
(December 1995), it was confirmed that corrosion had reappeared on the
exhaust valves (having utilised Fuel No. 1 BIA without additives), just
as corrosion had been detected in the first period of 3,000 hours. Following this overhaul at 6,000 hours (December 1995), MSM decided to
recommence the additive treatment of Fuel oil No. 1 BIA. Additive
treatment commenced on 8 January 1996, employing new additives developed by rb bertomeu S.L. : Period from January to October
1996: “rb bertomeu”
beco F + “rb bertomeu” beco Mg Period from October 1996
onwards: “rb bertomeu” beco F1/ASF The plant continued to run on Fuel oil No. 1 BIA treated with the
additive “rb bertomeu”
beco F1/ASF in a proportion of 0.5 litres per
metric tonne of fuel oil, until March 1998, when the changeover was made to
Fuel oil No. 1, and the same additive treatment with “rb bertomeu” beco F1/ASF was continued, as it had been
successfully employed throughout the previous two years and three months with
Fuel oil No. 1 BIA. From April 1998 to the present, the plant has continued to run on
various types of Fuel oil No. 1, always treated with the additive “rb bertomeu” beco F1/ASF, in the proportion of 0.5 litres per
metric tonne of Fuel oil. During the period between August 1995 and March 1999, MSM performed
the overhauls on the engines in question under the supervision of rb bertomeu S.L.,
who produced reports on the state of the exhaust valves. On the basis of
the data available, we shall proceed to analyse the differences encountered
in respect of the requirement for replacing exhaust valves and in
accumulation of residues according to the type of Fuel oil (whether
No. 1 BIA and No. 1) treated with the additive “rb bertomeu” beco F1/ASF. Prior to performing this analysis, the first obvious conclusion is
that Fuel oil No. 1 BIA cause corrosion problems on exhaust valves, and
that this corrosion was prevented or minimised with the additive “rb bertomeu”. This
was proven in 1995, when MSM operated with the same fuel, while alternating
between fuel treated with additives and untreated
fuel. It may be emphasised that since the time the engines were brought into
operation, the exhaust valves have not been changed (except for those replaced
due to corrosion, thermal fatigue or failing to conform to size).
Therefore the time elapsed or the actual life of the valves is always a
factor working to the detriment of the most recent period (in this case,
the period corresponds to the use of Fuel oil No. 1). 2. DATA ON FUEL OIL UTILISED
AND ITS ADDITIVE TREATMENT Period JANUARY
1996 to DECEMBER 1996 Fuel:
Fuel No. 1 BIA Additive
treatment:
January – October: "rb bertomeu" beco F + "rb bertomeu" beco Mg October – December: "rb bertomeu" beco F1/ASF
Typical analysis
of the Fuel oil No. 1 BIA
used:
Vanadium
=
31.1 ppm
Sodium
=
31.2 ppm
Sulphur
=
0.63 %
Viscosity at 50º =
202 cSt
Carbon residue =
9.4 %
Asphaltenes
=
4.2 %
Period JANUARY
1997 to DECEMBER 1997 Fuel:
Fuel No. 1 BIA Additive
treatment: "rb bertomeu" beco F1/ASF
Typical analysis
of the Fuel oil No. 1 BIA used:
Vanadium
=
34 ppm
Sodium
=
8.6 ppm
Sulphur
=
data unavailable
Viscosity at 50º = data
unavailable
Carbon residue = data
unavailable
Asphaltenes
=
data unavailable Period JANUARY
1998 to MARCH 1998 Fuel:
Fuel No. 1 BIA Additive
treatment: "rb bertomeu" beco F1/ASF
Typical analysis
of the Fuel oil No. 1 BIA
used:
Vanadium =
46.4 ppm
Sodium
=
48.2 ppm Sulphur
=
0.97 %
Viscosity at 100º =
24.5 cSt
Carbon residue =
9.4 %
Asphaltenes
=
4.2 %
Period APRIL 1998
to DECEMBER 1998 Fuel:
Fuel No. 1 Additive
treatment: "rb bertomeu" beco F1/ASF
Typical analysis
of the Fuel oil No. 1
used:
Vanadium
=
223 ppm
Sodium
=
21 ppm
Sulphur
=
2.31 %
Viscosity
at 100º =
24.7 cSt
Carbon
residue =
17.6 %
Asphaltenes
=
9.9 %
Period JANUARY
1999 to MARCH 1999 Fuel:
Fuel No. 1 Additive
treatment: "rb bertomeu" beco F1/ASF
Typical analysis
of the Fuel oil No. 1 used:
Vanadium
(*)
=
data unavailable
Sodium
=
data
unavailable
Sulphur =
data
unavailable
Viscosity at 100º =
data
unavailable
Carbon residue =
data
unavailable
Asphaltenes =
data
unavailable (*) Data
unavailable. Probably it was during this period, or the following period when
the analysis of vanadium in the fuel surpassed 300 ppm
on several occasions, according to verbal comments from MSM. Period APRIL 1999
to NOVEMBER 2002 Fuel:
Fuel No. 1 Additive
treatment:
Throughout the period: "rb bertomeu" beco F1/ASF
Typical analysis
of the Fuel oil No. 1
used:
Vanadium
=
data unavailable
Sodium =
data unavailable
Sulphur
=
data unavailable
Viscosity at 100º = data
unavailable
Carbon residue = data
unavailable
Asphaltenes =
data
unavailable
3. ENGINE OVERHAULS SUPERVISED
BY RB BERTOMEU S.L. Fuel
oil
Year
Overhaul (Hours) Engine(s)
Hours
Date No. 1 BIA 1996 9,000 H M-1 -- 19-04-96 M-2 -- 24-04-96
12,000 H M-1 11,868 28-08-96 M-2 12,195 02-09-96 M-3 12,283 04-09-96
No. 1 BIA 1997 15,000 H M-1 15,282 23-01-97 M-3 15,943 11-02-97
18,000 H M-1 18,029 27-05-97 M-3 18,409 05-06-97
20,000 H M-3 19,730 04-08-97 M-2 19,220 04-09-97
21,000 H M-3 21,498 07-11-97 M-1 21,610 11-11-97
No. 1 BIA 1998 24,000 H M-2 23,529 09-03-98
No. 1 + No. 1 BIA 25,000 H M-1 25,512 04-05-98 M-3 26,074 28-05-98
No. 1 25,000 H M-2 25,012 15-05-98
No. 1 28,000 H M-1 28,713 29-09-98 M-2 28,059 05-10-98 M-3 28,902 13-10-98
No. 1
1999
31,000
H
M-1
31,716
16-03-99
M-2
31,103
22-03-99
M-3
32,038
26-03-99 No. 1
36,000
H
DATA UNAVAILABLE Summary of
periods with documented overhauls supervised by rb bertomeu S.L. where the Fuel oil had always been treated
with additives from “rb bertomeu”: A) Overhauls when using exclusively Fuel oil
Nº 1 BIA:
From JANUARY 1996
until MARCH 1998 Engine overhauls
at 9,000 Hours, 12,000 Hours, 15,000 Hours, 21,000 Hours and 24,000 Hours
(only engine M-2) B) Overhauls when using Fuel oil No. 1 BIA
and Fuel oil No. 1 during the corresponding TBO: Engine overhauls
at 25,000 Hours (only engines M-1 and M-3) C) Overhauls when using exclusively Fuel oil
No. 1: From APRIL 1998
until MARCH 1999 Engine overhauls
at 25,000 Hours (only engine M-2), 28,000 Hours and 31,000 Hours
4. COMPARISON OF CONTROLLED
PARAMETERS WHEN USING FUEL NO. 1 BIA AND FUEL NO. 1 , BOTH TREATED
WITH “RB BERTOMEU” ADDITIVES 4.1 QUANTITIES OF INCRUSTED RESIDUES ON EXHAUST
VALVES with Fuel oil No.
1 BIA with
Fuel oil No. 1
Average residue (g/valve)
M-1
4.17
2.70 Average residue (g/valve)
M-2
3.13
2.58 Average residue (g/valve)
M-3
2.13
2.77 Overall average residue
(g/valve)
3.14
2.68 It may be observed that with
Fuel oil No. 1 BIA the incrusted residues on valves are slightly higher,
even though the differences are not significant. This falls in line with the
theory that the difference between the content in sulphur of both fuels (1%
for fuel BIA and 2.5% for fuel No. 1) has no significant influence on
the formation of residues, provided the TBN of the engine oil has been
adapted, given that the presence of residues caused by sulphur is more
dependent on the calcium found in the lubrication oil and the fuel oil
itself, than on a greater or lesser content in sulphur in the fuel oil,
because the content in sulphur was in stechiometric
excess with respect to calcium in each case. 4.2 LEVEL OF REPLACEMENT OF EXHAUST VALVES 4.2.1 Replacement with Fuel
oil No. 1 BIA: Period from January ’97 to March ’98 (15 months) Average Time in
operation in March ’98: 25,038 Hours Engine
No. 1 Engine No. 2 Engine No. 3
Total 3 Engines
Hours in operation 10,230
8,529
10,131
28,890
Valve
baskets
5
7
2
14
Valve cones
14
12
15
41
Valve baskets per
3,000
Hours
1.47
2.46
0.59
4.52
Valve spindles per
3,000
Hours
4.11
4.22
4.44
12.77 4.2.2 Replacement with
Fuel oil No. 1: Period from April ’98 to March ’99 (12 months) Average Time in
operation in March ’99: 31,619 Hours Engine
No. 1 Engine No. 2 Engine No. 3
Total 3 Engines
Hours in operation
6,204
7,574
5,964
19,742
Valve baskets
5
13
0
18
Valve
cones
19
20
6
45
Valve baskets per
3,000 Hours
2.41
5.15
0.00
7.56
Valve spindles per
3,000
Hours
9.18
7.92
3.02
20.12 4.2.3 Average increase
in the level of replacement of exhaust valves with the changeover from Fuel
oil No. 1 BIA to Fuel oil No. 1: VALVE BASKETS: + 67% (overall for the three
engines) VALVE CONES: + 57% (overall for the
three engines) |
©
rb bertomeu,
S.L. - Pol. Ind. Fondo de Llitera, Par. 82-83 - E-22520
Fraga, Huesca (Spain) Tel.:
+34 974 47 48 04 / +34 630 43 08 43 |