Cairo Electricity Production Company CEPC

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Cairo Electricity Production Company (CEPC)
The Impact of Chemical Additives of fuel to
improve Generating Plants performance WEC-PGP
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Contents

• CEPC Overview.
• CEPC Statistics.
• Introduction for heavy fuel firing.
• Cairo West case study

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• CEPC Overview

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Cairo Electricity Production Company (CEPC)

• CEPC is a state-owned firm, affiliated to the
  Egyptian Electricity Holding Company (EEHC).
• CEPC has a total installed capacity of 4,605 MW,
  representing 20 of the total installed capacity
  connected to the unified national grid.
• In all power plants, CEPC has a group of
  workshops that are adequately equipped to serve
  the maintenance activities of these power plants.
  CEPC has its own qualified and skilled staff for
  maintenance and operation of CEPC power plants.

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Cairo Electricity Production Company (CEPC)

• CEPC has established a central workshop at 10th
  of Ramadan city to be specialized in the
  manufacturing of steam boilers equipment for CEPC
  and other EEHC affiliated Companies.
• All the power generation units owned by CEPC are
  environmentally friendly and operate under the
  limits allowed by the Egyptian environmental law.
• CEPC objectives cover production, management,
  operation, maintenance, and sale of electric
  power from its owned power plants. Furthermore,
  implementation of new power plants projects as
  per EEHC plan, and conduction of researches and
  studies within CEPC generation zone.

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Ismalia Canal
CEPC Power Stations
Shoubra El-khaima Power Station Cairo West Power
Station Cairo South Power Station Cairo North
Power Station Wadi Hoff Power Station
Nile River
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CEPC Power Stations
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• CEPC Statistics

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CEPC Generated Energy Development (KWH)
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CEPC Distributed Energy by Plants2007-2008
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CEPC Generation Supply Mix 2007/2008
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CEPC Power Plants Statistics
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Fuel Type Consumption2007/2008
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Percentage Of Nat. Gas Mazout per Total Fuel
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Cairo West Mazout Consumption
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• Introduction for Heavy Fuel Firing

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Introduction

• Today, about 90 of the total energy production
  all over the world is provided by combustion of
  fossil fuels. Unfortunately, hydrocarbon
  combustion has a major impact on the global
  environment through the emission of CO2, which is
  a greenhouse gas.
• The increase in consumption of petroleum-derived
  liquids as fuel for transportation, electric
  power generation, heating, and process
  engineering is resulting in a reduction in the
  quality of residual oils that are becoming
  heavier. This quality reduction translates into
  lower heating values, but above all, into higher
  viscosity, as well as higher levels of
  asphaltenes, Conradson carbon, etc. At the same
  time, the world natural reserve of bituminous
  petroleum is estimated to be three times higher
  than that of regular fuel oils.

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• Combustion of heavy oils contain vanadium,
  sulfur, and sodium contents results in highly
  corrosive deposits. The slag produced during
  combustion has a low melting temperature and
  adheres to hot metal surfaces (450oC and above).
  Vanadium salts are extremely corrosive, since
  they dissolve the protective oxide film on the
  metal surface and then transport oxygen to the
  clean surface that corrodes.
• During combustion, such elements give rise to
  complex low-melting-point compounds. These sticky
  deposited materials capture ash, soot, and coke,
  which reduce the heat transfer and cause
  corrosion.

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Effects of Ash Deposition

• Slag build-up reduces the heat transfer from
  combustion into the water tubes.
• Even minor slag thickness reduce heat transfer
  significantly.
• This reduces steam temperature and steam
  production.
• To compensate, fuel consumption is increased.
• Loss of refractory is possible when severe
  slagging occurs.
• Results in lower Heat Rate (Tones Fuel/MW).

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Secondary Superheat Pipes
Before
After
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Furnace Bottom Pipes
After
Before
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Reheat Pipes
Before
After
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Primary Superheat Pipes
Before
After
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Cold End Corrosion

• Very detrimental as will corrode metal surfaces
  within the hot gas path if acid dew-point is
  achieved in the system.
• Collects fly ash therefore increases ash fouling
  rates, blocking passages in air heaters etc.
• Stack exit temperature run hotter
• Reduces Efficiency.

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Gas/Air Heater Baskets
Before
After
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Gas/Air Heater Baskets
Before
After
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Various Methods to Prevent Boiler Corrosion

• Use of high quality fuel.
• Flue gas desulphurization.
• Use of chemical additives (applicable method).

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Main Effects of using Additives in Oil-Fired
Boilers

• Reduce emissions of SO3 and acid smut.
• Minimize corrosion in air heaters, economizers,
  furnaces and super heaters.
• Reduce tube fouling.
• Reduce flue gas opacity.
• Prevent slagging and deposits.
• Improve soot quality and reduce soot quantity.

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• The most effective among the several fuel
  additives used are based on MgO or Mg(OH)2, which
  are generally available in oil dispersed forms.
  Magnesium additive is the best choice for three
  reasons
• They combine with the vanadium oxides and hence
  increases the melting point of the ash components
  to a level above the system temperatures so they
  are no longer sticky.
• They modify the ash that does form to a soft,
  powdery and extremely friable form.
• They effectively neutralizes the acid that
  condenses on the cooler parts of the air heating
  system forming neutral MgSO4.

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• Cairo West Case Study

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Cairo West Power PlantCase Study

• This paper presents the trial tests carried out
  for the performance evaluation of one (MgO) of
  the three chemical additives selected at Cairo
  West Plant. The plant has 2 oil-fired boilers,
  which provide high-pressure steam for operation
  of turbine driven generators. The fuel oil used
  in the boilers is high sulphur, low vanadium
  residual oil supplied by Misr Petroleum Company.

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Objectives of Study

• To evaluate the performance of different Fuel
  Chemical Additives in reducing Stack Emissions
  and increasing combustion efficiency.
• To determine the effect of additives on SO3, SO2
  and NOx generation and acid dew point.
• To evaluate the quality and quantity of soot/dust
  production.
• To determine the optimum dose rate.
• To evaluate hot and cold side corrosion rates
  with and without additive.

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EXPERIMENTAL

• Cairo West Boiler 6 was selected for the trial
  tests as the test unit because it had the
  independent tank facility for chemical additive
  dosing. This boiler is Hitachi make with a
  maximum capacity to generate 330 MW power, steam
  flow 1013t/h, and fuel flow 70t/h. It has 12 on 2
  levels steam assisted burners.
• The test unit was put in operation and after
  achieving stable condition operational and
  chemical parameters were monitored without dosing
  any chemical additive for two weeks. Then the
  chemical was dosed at the high rate of 10L/hr to
  achieve stabilization (pH at 5min. 4.2).

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Analytical Parameters and Procedures

• Flue gas analysis
• The following parameters were determined in the
  boiler flue gases after the air heater (at the
  stack) as per the methods indicated against each
• SO2, NOx, CO, CO2, O2, hydrocarbons and flue gas
  temperature were monitored using a portable flue
  gas analyzer (Madur).
• Acid dew point and Rate of Build Up (RBU) of acid
  were determined using a portable Land (Model-200)
  instrument.

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• Ash (Soot) Analysis
• Regular soot samples were collected and analyzed
  for the following parameters
• pH (at 5 min. 60 min.).
• Acid content of ash as H2SO4 by titrimetry
  (Acidity).
• Fuel Oil Analysis
• Fuel oil used during the study were withdrawn
  from the storage tanks and given for analysis to
  external agencies (Table 1).
• The following parameters were analyzed
• Physical Parameters Gravity, Viscosity at 50 oC
  and gross calorific value.
• b. Chemical Parameters Carbon, Nitrogen,
  Hydrogen, Sulphur, Vanadium and Sodium.

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• Boiler Shut Down Inspection
• Internal inspection of the boiler was carried out
  at the end of additive testing. Besides visual
  checks and photographic documentation chemical
  analysis of several deposit samples were carried
  out.

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RESULTS

• Flue gas Characteristics
• a. Acid Dew Point
• Variation of acid dew points as a function of
  time is shown in Figure 1.The dew points before
  the additive dosing showed an average value of
  148 oC.
• After additive dosing the dew points varied in
  the range of 130 135 oC, a decrease of 15
  20oC is realized. This could be considered quite
  a significant improvement obtained by additive
  dosing.

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CAIRO WEST POWER STATION Unit 6
Result of Dew pointduring 6/11/2008 to
19/2/2009For PentoMag
Fig.1
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• Soot/Ash Characteristics
• a. pH and Sulphuric Acid Content (Acidity)
• pH of the ash sample collected before additive
  dosing showed an average of 1. Dramatic increase
  was noticed with additive dosing. At the dose
  rate of 340 ppm the pH at 5 min. and 60 min.
  showed an average value up to 4.2 (Fig. 2,3).
• Acidity of the ash sample collected showed a
  result 27 acidity, and after dosing (340ppm) is
  decreased to average value around 0 to 1, as
  shown in Fig. (4).
• Quality Control of Fuel Oil
• Samples of the fuel oil were analyzed during the
  course of the study and the results are shown in
  the Table 1.

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CAIRO WEST POWER STATION Unit 6
Result of PH- 5minduring 6/11/2008 to
19/2/2009For PentoMag
Fig.2
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CAIRO WEST POWER STATION Unit 6
Result of PH- 60minduring 6/11/2008 to
19/2/2009For PentoMag
Fig.3
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Result of Acidity ()during 6/11/2008 to
18/2/2009For PentoMag
CAIRO WEST POWER STATION Unit 6
Fig.4
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Table (1)Fuel Oil Specifications
Average Values for the last 6 years analysis.
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• Operation Parameters
• Boiler Load
• Attempts were made to maintain load at a constant
  level during the course of the test period in
  order to reduce variation on different test
  parameters. Boiler efficiency remained almost
  constant ( 88.8) before and during the additive
  dosing. It is very important to note that the
  efficiency of the boiler was not affected as a
  result of additive dosing. On other side the load
  does not decreased due to ash contamination in
  the air heater during the test (Fig.5).
• Air Heater Dp
• The pressure differential (?p) across the air
  heaters was monitored continuously in order to
  check fouling of air heaters due to the additive
  dosing. As seen from Figure 5, ?p across the air
  heaters remained steady, this indicates no
  fouling due to additive dosing Fig. 6.

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Relation time Max LoadBefore After using
Fuel additive
CAIRO WEST POWER STATION Unit 6
Fig.5
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Result of Gas Dp at GAH (mmc) during 8/10/2008
to 15/12/2008
CAIRO WEST POWER STATION Unit 6
After cleaning before pentomag
After pentomag
Fig.6
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• Boiler Inspection
• On 24/12/2008 the boiler was shutdown and the
  following parts was inspected.
• (a) Combustion Chamber (Furnace).
• (b) Super Heater.
• (c) Economizer.
• (d) Air Heater (upstream and downstream).
• Heating Elements.

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• Results of Boiler Inspection
• Condition of the furnace was generally good with
  soft scales on the tubes and some loose hard
  deposits in between the tubes.
• Primary super heater tubes were found to have a
  uniform of 2-3 mm thickness of thin scales. The
  scales were yellowish white and soft powdery
  material
• Flue ducts at upstream and down stream of the air
  heater had uniform grayish deposits.
• Air heater elements were found to be generally
  satisfactory at the upstream (hot end) but the
  down stream (cold end) air heater elements were
  found to be dirty

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CONCLUSIONS

• The neutral character of the boiler soot
  generated during the additive dosing further
  confirmed the Non-corrosive nature of the flue
  gas. Soot samples were found to be dry and
  friable. The average pH of 3 and 4.5 at 5 minutes
  60 minutes, and no free acidity or very little
  total acidity at the dose rate of 340 ppm showed
  by the soot samples indicated the neutral and
  non-corrosive nature.
• Boiler efficiency was not affected due to
  additive dosing. Appreciable increase (30 40
  oC) in the flue gas exit temperature (economizer
  out/GAH in) was noted during the additive dosing,
  which is presumably due to the formation of
  reflective coating (whitening effect) of neutral
  compounds on the heat exchange surfaces reducing
  the heat transfer capacity however, the boiler
  efficiency was not affected.

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• On dosing of chemical fuel additive sufficient
  reduction in Acid Dew Point was observed thereby
  avoiding cold end corrosion.
• Air heater ducts were found to be covered with
  neutral magnesium compounds which are effective
  in preventing corrosion of metallic parts in the
  area where the temperatures are below the acid
  dew points as a result of which there is
  condensation of acidic flue gases that leads to
  corrosion.
• No adverse effects were noticed on the internals
  of the boiler due to additive dosing. Heat
  exchanger tubes in the super heater and
  economizer areas were found to have deposits of a
  thickness of 2- 4 mm, which were soft, and in the
  form of flakes.

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Thank You for Your Kind Attention