MAC Boiler Manual (Extract)

K1D97-N57-10M-M501

2. Outli ut line ne of Marine Boil Bo ile er & Acce Acc ess ssori orie es 2.1

Boiler This installation consists of two drum water tube “MITSUBISHI MAC-**BF” type marine boiler with oil and gas combination burners located in the furnace roof. The unit is composed of a steam drum and a water drum connected by a bank of inclined generating tubes. Other water side components include : front screen tubes, side and roof water wall, front and rear water wall tubes, down-comers, roof and bottom front wall headers, and roof and bottom rear wall headers. Each tube in the furnace floor, side & roof, front and rear wall are jointed to the adjacent tube by welding. In this welded wall construction, the tubes forms a gas-tight envelop three side of the furnace. Since the combination burners are located in the furnace roof, the gas flow from the furnace is evenly distributed across the front bank and generating banks, then, discharged from the uptake of boiler.

Fig 2-1

Construction of Marine Boiler

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3-1

K1D97-N57-10M-M501

2.2 2.2

Drum Internals Steam drum internals consists of surface blow line, internal feed pipe, chemical feed line, baffles and dry box. Steam generated in the boiler tubes enters the steam drum, where it is forced to pass through a baffle located at the normal water level before entering the upper part of the steam drum. Before leaving the boiler through the outlet nozzle, the steam must pass through the dry box located at the top of the drum. Manholes fitted with hinged manhole covers are provided in the front head of the steam drum and water drum. The hinges allow the manhole covers to swing into the drum clear of the manhole.

2.3

Furnace Water cooled walls are provided by lining the furnace side, floor and roof with a single row of 88.9 mm tubes, and front and rear with a single row of 76.2 mm tubes. External down comers provide ample circulation to water drum. The water cooled floor consists of 88.9 mm tubes traversing the furnace floor from the water drum, then bending to form the furnace side and roof, which terminates in the steam drum. Furnace front and rear wall tubes arranged from the lower to the upper water wall headers cover front and rear furnace walls. Upper front and rear water wall headers are connected to the steam drum. Because water wall tubes are jointed to their adjacent tubes in a welded wall construction, they form a gas tight envelops lining the furnace. Where openings are required for burners, access doors and soot blowers, they have been formed by bending tubes back and to the side to form the opening and then back to their original plane to continue the welded wall construction. The furnace water wall tubes including reheat furnace are backed up by insulation buck-stays and a corrugated casing.

2.4

Saddles Saddles are provided under the water drum and the front & rear water wall headers to support the weight of the boiler. Rear saddle under the water drum is fixed and the front saddle has slotted bolt holes, grooves and grease fittings to allow easy movement and lubrication. Grease fittings are provided on both front and rear saddle of water wall header. The grooved saddles are free to slide to allow for expansion of the boiler as it is warmed up. The sliding feet should be inspected and cleaned as frequently as possible and should be greased at least each 600 boiler steaming hours. This procedure is extremely important and should be followed without failure. There are cases on record where pressure parts have failed because the sliding saddles and frozen in place, preventing movement required during normal expansion.

MHI-MME Proprietary Proprietary Information

3-2

K1D97-N57-10M-M501

2.2 2.2

Drum Internals Steam drum internals consists of surface blow line, internal feed pipe, chemical feed line, baffles and dry box. Steam generated in the boiler tubes enters the steam drum, where it is forced to pass through a baffle located at the normal water level before entering the upper part of the steam drum. Before leaving the boiler through the outlet nozzle, the steam must pass through the dry box located at the top of the drum. Manholes fitted with hinged manhole covers are provided in the front head of the steam drum and water drum. The hinges allow the manhole covers to swing into the drum clear of the manhole.

2.3

Furnace Water cooled walls are provided by lining the furnace side, floor and roof with a single row of 88.9 mm tubes, and front and rear with a single row of 76.2 mm tubes. External down comers provide ample circulation to water drum. The water cooled floor consists of 88.9 mm tubes traversing the furnace floor from the water drum, then bending to form the furnace side and roof, which terminates in the steam drum. Furnace front and rear wall tubes arranged from the lower to the upper water wall headers cover front and rear furnace walls. Upper front and rear water wall headers are connected to the steam drum. Because water wall tubes are jointed to their adjacent tubes in a welded wall construction, they form a gas tight envelops lining the furnace. Where openings are required for burners, access doors and soot blowers, they have been formed by bending tubes back and to the side to form the opening and then back to their original plane to continue the welded wall construction. The furnace water wall tubes including reheat furnace are backed up by insulation buck-stays and a corrugated casing.

2.4

Saddles Saddles are provided under the water drum and the front & rear water wall headers to support the weight of the boiler. Rear saddle under the water drum is fixed and the front saddle has slotted bolt holes, grooves and grease fittings to allow easy movement and lubrication. Grease fittings are provided on both front and rear saddle of water wall header. The grooved saddles are free to slide to allow for expansion of the boiler as it is warmed up. The sliding feet should be inspected and cleaned as frequently as possible and should be greased at least each 600 boiler steaming hours. This procedure is extremely important and should be followed without failure. There are cases on record where pressure parts have failed because the sliding saddles and frozen in place, preventing movement required during normal expansion.


3-2

K1D97-N57-10M-M501

2.5

Economizer An extended extended surface surface type economiz economizer er is placed placed above above the the boiler tube bank. bank. The The economizer economizer is made up of closely spaced continuous loop elements, which is welded to the terminal headers at both ends. Each element shall be of 38.1 mm tubes straight carbon steel tubes with spiral steel fin, connected by U-bends forming integral loop. All elements are supported at the front and rear side by tube plates. On the outside of the terminal headers, handholes with covers are provided. Insulated steel casings are provided around the economizer and large removable panels are fitted on the front and rear side for access and tube removal. Feedwater enters the inlet header at the top and flows through the elements counter flowing to the gas leaving the boiler, to the lower header, thence to the boiler steam drum.

2.6 2.6

Boil er Accessor ies Boiler accessories are listed on this section later with the manufacture’s name and identifying data. See instruction books of those accessories for detailed description.

2.6. 2.6.1 1

Oil / Gas Gas Combi natio n Burner Bu rner

The boiler is equipped with two (2) sets of fuel oil and gas combination burners on the roof wall of the furnace. The fuel combination burner is of steam assisted pressure jet type, consisting of atomizer gun, forced draft air register with fuel shut off valve. The fuel is distributed to each burner from a burner manifold by branch connection pipe. The operation of start or stop of the burners is automatically operated by the automatic combustion control signal, and remotely operated by the push button when necessary. Note; Oil / Gas Gas combin ation burners are provid ed by Hamworhy Combustio n, hence instruction details to check their instruction manuals.

2.6. 2.6.2 2

Auto matic Combust ion Control

The control system is capable of controlling each boiler separately or all boilers together. The control system is also capable of burning fuel oil only, fuel oil / gas together or fuel gas only at normal operating condition. The boiler is arranged for all equal load sharing and each is capable of operating in a single boiler mode. The restart of one boiler and transfer to gas firing does not affect the continued operation of the other running boiler. The system control total fuel quantity and combustion air quantity according to steam demand, and to maintain steam pressure constantly at main steam outlet. The total fuel quantity for each boiler is the sum of fuel oil flow and gas flow to each boiler. The calibration of these signals is such that they are of equivalent calorific value. Combustion air for burner is supplied by forced draft fan. And combustion air quantity is controlled in accordance with total fuel quantity by the forced draft fan inlet vanes. Note; Automatic comb ustion c ontro l system is provi ded by Hamworhy Hamworhy Combustion, hence instruction details to check their instruction manuals.


3-3

K1D97-N57-10M-M501

2.6.3

Feed Water Regulator

The boiler water level control system shall be two (2) element type sensing steam flow and drum level. The feed water flow is controlled automatically by the regulating valve in accordance with variation of water level to maintain the water level constant. And steam flow is used as feed forward signal. The water flow can be also adjusted manually and independently. In case of control air supply failure, the regulating valve is locked. Note; Feed water control sys tem is provi ded by Hamworhy Combus tion, hence instructio n details to check their instruc tion manuals.

2.6.4

Burner Management System

The BMS is a system operated by manual local / remote control of FO and GAS fired burners or by automatic operation linked with ACC. Should any abnormality occur the BMS system will, after indicating an alarm, trip the fuel supply to the boiler which is in an abnormal condition. Note; Burner management system is pro vided by Hamworhy Combus tion, hence instructi on details to check their instruc tion manuals.

2.6.5

Soot Blo wer

The boiler is equipped with soot blower system of steam nozzle tube type to clean the external surface of tubes. The tunmber of soot blowers are as follows: Position

No.

Type

Boiler bank tube

Two (2)

Stationary rotary

Economizer

Six (6)

Stationary rotary

Soot blower of stationary rotary is driven by electric motor. All soot blowers are automatically and sequentially operated from the soot blower operating panel at control room. Note; Soot blower contro l system is pro vided by Hamworhy Combust ion, hence instruc tion details to check their instruc tion manuals.

2.7

Manufactu rer Lis t for Boi ler Acc essories Equipment

(1)

Oil / Gas Combination Burner

Manufacturer Hamworthy Combustion Engineering Limited,

Boiler & Soot blower controls Boiler instruments (2)

Safety Valve

Fukui Seisakusho Co., Ltd.

(3)

Soot Blower

Clyde Bergemann Ltd.

(4)

Water Level Gauge

Nihon Keiki Co., Ltd.

(5)

Valves mounted on the boiler

Mitsumoto Valve Mfg Co., Ltd.

(6)

Feed water control valve

Nippon Fisher Co., Ltd.

(7)

Chemical Dosing Equipment

Taiwan Nikkiso Co., Ltd.

MHI-MME Proprietary Information

3-4

K1D97-N57-10M-M501

2.8

Design Data PRESSURES (bar) Design ················· ················ ··············· ················ ··············· ··········· 18 Operating (Main Steam Outlet)····· ····· ····· ····· ····· ····· ···· ···· ····· ···· ···· ····· ··· 16 Hydrostatic Test (Maximum) ······· ····· ····· ····· ····· ····· ····· ····· ····· ····· ····· ····· 27 Safety Valve Settings: Steam Drum················ ··············· ··············· ··············· ················ 18 Economizer·············· ················ ················ ················ ·············· 22.5

TEMPERATURE (degree C) Steam ················· ··············· ················ ··············· ················ Saturated Feed Water ·························· ··············· ················ ··············· ·········· 135 EVAPORATION (kg/h) Maximum Capacity ···································································· 80,000 3

FURNACE VOLUME (m ) Furnace········· ················ ················ ················ ················ ·············· 84.7 2

HEATING SURFACE (m ) Boiler ················· ················ ················ ··············· ················ ·········· 955 Economizer·············· ················ ··············· ················ ················ ···· 1542 WEIGHT (kg) Total Cold Water to Fill Unit Completely ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ·· 41,800 Cold Water to Fill Boiler to Normal Level ········································ 30,400 Cold Water to Fill Economizer ····· ····· ····· ····· ····· ····· ···· ···· ····· ····· ····· ··· 2,200 Boiler, Dry, Complete with Burners and Soot Blower ························· 85,600 Economizer, Dry Complete with fittings ·········································· 24,400 Boiler Water, Steaming Condition ·· ····· ····· ····· ····· ····· ····· ····· ···· ····· ··· 26,100 Economizer Water, Operating Condition··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· · 2,200 Total One Boiler, Steaming Condition ···· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· 111,700 Total One Economizer, Operating Condition··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· ··· 26,600


3-5

K1D97-N57-10M-M501

2.9

Tube Data Location (Material)

Quantity / BLR

Diameter

Thickness

mm

mm

Rear Bank Tubes

928

50.8

2.9 or 3.2

Roof, Side & Floor Water Wall Tubes

45

88.9

5.5

Front Water Wall Tubes

33

76.2

4.0

Rear Water Wall Tubes

33

76.2

4.0

Front Bank Tubes

45

88.9

5.5

Rear Bank Front Wall Tubes

16

76.2

4.5

Rear Bank Rear Wall Tubes

16

76.2

4.5

Gas Outlet Water Wall Tubes

32

88.9

5.5


3-6

K1D97-N57-10M-M501

2.10 Perfo rmanc e Data and Curve 1. AUXILIARY BOILER PERFORMANCE DATA & CURVE MAC-80BF(100B) BOIL ER EXPECTED PERFORMANCE DATA FOR GAS FIRING 4

Natural Gas Case

LOAD

%

10

25

50

75

100

EVAPORATION

kg/h

8,000

20,000

40,000

60,000

80,000

DRUM PRESSURE

bar

16.0

16.0

16.0

16.0

16.0

FEED WATER TEMPERATURE

deg.C

135

135

135

135

135

SATURATED STEAM TEMPERATURE

deg.C

204.3

204.3

204.3

204.3

204.3 4

%

BOILER EFFICIENCY (LHV B ASE)

87.8

89.9

90.6

90.4

90.0

1

HHV

MJ/kg

53.85

53.85

53.85

53.85

53.85

LHV

MJ/kg

48.76

48.76

48.76

48.76

48.76

kg/h

416

1,015

2,015

3,028

4,056

EXCESS AIR RATE

%

25

16

9

8

7.5

O2 RATE

%

4.3

2.8

1.7

1.5

1.5

kg/h

8,930

20,050

37,430

55,770

74,570

kg/h

9,350

21,070

39,450

58,800

78,630

m3/h

11,250

26,610

52,310

77,980

107,180

AMBIENT AIR TEMPERATURE

deg.C

25

25

25

25

25

FLUE GAS TEMPERATURE AT ECONOMIZER OUTL ET

deg.C

138

144

155

169

184

CALORIFIC VAL UE

FUEL CONSUMPTION

1

COMBUSTION AIR FLOW

FLUE GAS FLOW

2

Note) - Flue gas flow of vo lume base is actual cond ition volume flow at boiler outlet, not stand ard conditio n volume flow. - Maximum flu e gas temperature at boiler out let is abou t 450 degree-C. - In case that ambient air temperature is 28 degree-C, boiler expected performance d ata is the same with above figure.

2

1

FUEL GAS CHEMICAL COMPOSITION Nitrogen : Methane : Ethane : Propane : Butane : Pentane or Heavier : Water :

1.0800 Vol % 96.7299 Vol % 0.9890 Vol % 0.0000 Vol % 0.0000 Vol % 0.2701 Vol % 0.9380 Vol %


3-7

K1D97-N57-10M-M501

1. AUXILIARY BOILER PERFORMANCE DATA & CURVE MAC-80BF(100B) BOIL ER EXPECTED PERFORMANCE DATA FOR MGO FIRING 4

LOAD

%

10

25

50

75

100

EVAPORATION

kg/h

8,000

20,000

40,000

60,000

80,000

DRUM PRESSURE

bar

16.0

16.0

16.0

16.0

16.0


deg.C

135

135

135

135

135


deg.C

204.3

204.3

204.3

204.3

%

88.1

90.5

91.4

91.4

91.0

HHV

MJ/kg

46.01

46.01

46.01

46.01

46.01

LHV

MJ/kg

43.12

43.12

43.12

43.12

43.12

kg/h

469

1,141

2,258

3,388

4,536

EXCESS AIR RATE

%

49

31

18

16

15

O2 RATE

%

6.9

5.0

3.2

2.8

2.7

kg/h

10,370

22,170

39,420

58,140

77,370

kg/h

10,840

23,320

41,680

61,530

81,910

m3/h

12,690

28,870

54,700

80,310

107,390

AMBIENT AIR TEMPER ATURE

deg.C

25

25

25

25

25

FLUE GAS TEMPERATURE AT ECONOMIZER OUTL ET

deg.C

139

145

154

167

181

BOILER EFFICIENCY (LHV B ASE)

4

204.3

CALORIFIC VALUE

FUEL CONSUMPTION

COMBUSTION AIR FLOW

FLUE GAS FLOW

2

4

Note) - Flue gas flow of volume base is actual condition volume flow at boiler outlet, not standard con dition volume flow. - Maximum flu e gas temperature at bo iler outlet i s abou t 450 degree-C. - In case that ambient air temperature is 28 degree-C, boiler expected p erformance data is the s ame with above figure. FUEL OIL : MGO (ISO 8217 DMA grade)


3-8

K1D97-N57-10M-M501

1. AUXILIARY BOILER PERFORMANCE DATA & CURVE

3

MAC-80BF(100B) BOILER EXPECTED PERFORMANCE DATA FOR Crude Oi l FIRING 4

LOAD

%

10

25

50

75

100

EVAPORATION

kg/h

8,000

20,000

40,000

60,000

80,000

DRUM PRESSURE

bar

16.0

16.0

16.0

16.0

16.0


deg.C

135

135

135

135

135


deg.C

204.3

204.3

204.3

204.3

%

88.1

90.5

91.4

91.4

91.0

MJ/kg

40.7

40.7

40.7

40.7

40.7

kg/h

497

1,209

2,392

3,590

4,806

EXCESS AIR RATE

%

49

31

18

16

15

O2 RATE

%

6.9

5.0

3.2

2.8

2.7

kg/h

10,290

21,990

39,090

57,670

76,730

kg/h

10,790

23,200

41,490

61,260

81,540

m3/h

12,740

29,060

55,290

81,200

108,590

deg.C

25

25

25

25

25

deg.C

139

145

154

167

181

BOILER EFFICIENCY (LHV BASE) CALORIFIC VALUE

LHV

FUEL CONSUMPTION

COMBUSTION AIR FLOW

4

204.3

FLUE GAS FLOW

AMBIENT AIR TEMPERATURE FLUE GAS TEMPERATURE AT ECONOMIZER OUTLET

4

Note) - Flue gas flow of volu me base is actual conditio n volume flow at boiler out let, not stand ard conditio n volume flow. - Maximum flue gas temperature is about 450 degree-C. - In case that ambient air temperature is 28 degree-C, boiler expected p erformance data is th e same with above figure. FUEL OIL : Cru de Oil (LHV : 40.7 MJ/kg) Methane : 0.177 mol % Ethane : 0.017 mol % HC Liquids : Balance


3-9

K1D97-N57-10M-M501

1. AUXILIARY B OILER PERFORMANCE DAT A & CURVE MAC-80BF(100B) BOILER EXPECTED PERFORMANCE CURVE

4

3

96.0 MGO

94.0

Natural Gas Crude Oil

] 92.0 % [ y c n90.0 e i c i f f E88.0

86.0 84.0 0

10

20

30

40

50

60

70

80

90

100

80

90

100

80

90

100

Boiler Lo ad [%] 1

6,000 MGO

Natural Gas

Crude Oil

] 5,000 h / g k [

4,000

n o i t p m3,000 u s n o C2,000 l e u F1,000

0 0

10

20

30

40

50

60

70

Boiler Loa d [%]

6.0 MGO

5.0

Natural Gas Crude Oil

] 4.0 % [ e t a3.0 R 2 O

2.0 1.0 0.0 0

10

20

30

40

50

60

70

Boil er Load [%]


3-10

K1D97-N57-10M-M501

3.7.6 Limi ts of Chemical Concentration

pH at 25 deg.C

Feed Water

Boiler Water

8.5

10.5

～

9.7

11.5

～

Hardness (as CaCO3)

mg/L

Not detected

-

Dissolved Oxygen

mg/L

0.5 or less

-

Oil

mg/L

Phosphate Ion (PO43-)

ppm

-

10

Silica (SiO2)

mg/L

-

50 or less

Chloride Ion (Cl )

mg/L

-

150 or less

Dissolved Solid

mg/L

-

-

-

To be kept low as far

-

as practicable

～

30

Note 1 : Feed water in this table means the mixture of condensate and distilled water to supply into the boiler. Note 2 : Estimate the pH value from alkalinity tends to give pH readings varying with silica, Ca, Mg, and other salt contents of boiler water and hence is not necessarily deemed appropriate : resort to this method only as a means to obtain a rough guide (alkalinity serves merely as an marine means in determining the pH level). Also, be sure to control pH to the target value while, on the other hand, keeping alkalinity at the minimum necessary level. Limiti ng the P alkalinity to within a certain range would make it possible to inhibit the alkali corrosion even if boiler water concentration should t ake place on the heating surface, etc.


3-16

K1D97-N57-10M-M501

3.7.7 (1)

Chemicals and Quantity for Boi ler Water & Feed Water Chemicals to be used 3-

(2)

For adjusting pH value and PO4

: NaOH and Na3PO4

For deoxidization and rising pH value

: Hydrazine hydrate

12H2O

･

Dosage A. Initial dosage Pressure[P] (MPa) Chemicals Na3PO4

12H2O (g/ton)

・

NaOH (g/ton) Resulting

PO4 (ppm)

values

pH

(-)

P≦1

1
2
120

120

40

90

30

21

30

30

10

11.4

11.0

10.8

(1) Above dosage is determined as the water hardness of zero. (2) In the initial phase of operation, reaction with iron content of boiler steel produces iron phosphate film on the steel surfaces causing phosphoric acid to remain below the specified limit. B. Supplementary dosage (per one boiler) Adjustment of chemical concentration should be done to satisfy the limitations based on the analysis after initial dosing. Following table gives the amount to be done. Chemicals

Dosage for

Value

adjustment (g/ton)

Required to raise phosphoric acid

About 40

Na3PO4 12H2O ･

3-

radical (as PO4 ppm) by 10ppm, g/ton

(1) The injection quantities indicated are calculated assuming distilled water to be used as boiler feed water. (2) The values given are mere theoretical targets and hence require to be controlled as appropriate for actual boiler load and feed water quality so that the desired boilerwater quality can be ensured in each particular application. (3) Example for Boiler Treatment Chemicals Marker Drew Marine Co.Ltd. Chemicals PO4 enchanting agent

ADJUNCT B

pH enchanting agent

GC


3-17

K1D97-N57-10M-M501

3.7.8

Fuel Trip and Alarm Point of Water Level

0 0 2

5 . 2 7

5 7 3

5 . 7 5

0 4 2

5 7 3

0 0 2

Note : Remote water level indication is supplied by Hamworthy Combustion


3-18

K1D97-N57-10M-M501

3.7.9

Relatio n between Drum Water Level and Water Content


3-19

K1D97-N57-10M-M501

3.7.10

Boiler Pressur e Raising Curve

Boiler Pressure Raising Curve 2

1.5

) a P M (

e r u s s e r 1 P m u r D

0.5

0 0

60

120

180

Operating Time After Light Up (minute)


3-20

K1D97-N57-10M-M501 4.

Outline of Maintenance

4. Outline of Maintenance 4.1

Feed Water & Boiler Water Treatment Feed water and boiler water shall be analyzed at least once a day. Amount of chemicals to be added and amount of boiler water to be blow down shall be controlled referring to the results of the analysis so as to maintain each chemical content of the water within the prescribed limit. Operators are required to have correct understanding about the action and effect of each chemical and calculation method of required quantity of it. Recommended chemicals are as follows 3-

For adjusting pH value and PO4

: NaOH and Na3PO4

For deoxidization and rising pH value

: Hydrazine hydrate

12H2O

･

Keep quality of bo iler water and feed water correctly.

4.2

Maintenance duri ng Shutdown There are two ways of laying up the boiler, dry and wet. Either way may be adopted as the case may be. When the boiler is laid-up wet, care should be taken to the concentration of chemicals in the boiler water, and when the boiler is laid-up dry, care should be taken to the effectiveness of the drying agent.

4.3

Hydro static Test There are two kind of hydrostatic test, one for checking water-tightness of pressure parts and the other for checking strength of the same. Test pressure should be determined to suit the case.


4-1

K1D97-N57-10M-M501 4.


4.4 Boil ing Out Boiling out is intended to cleanse the boiler internal surface of oil and grease. The boiler is filled with high alkaline solution and is heated for a predetermined duration by means of steam or by burning oil whichever the occasion demands. Boiling out by burning oil is often made to serve as burning and drying out refractory used in the boiler setting, too. Recommended duration of boiling out for a new boiler is 2

3 days.

～

Boiling out chemicals is highly corrosive.

4.5

Water Wash ing Hot water washing is intended to remove sludge sticking to the gas side of the boiler that cannot be blown off by soot blowing. There are two ways for hot water washing, one by use of soot blowers and the other by use of a temporary hand nozzle. Both ways have their own merits, either way may be adopted as the case may be. Hot water washing is generally required 6

8 hours. Hot water air heater shall be washed by use of water hose.

～

Recommended hot water temperature is about 80 degree C and pure water of 50 ton shall be required.

4.6

Acid cleaning Acid cleaning is intended to remove scales on the water side of the boiler. Inhibited hydrochloric acid solution is generally used for this purpose. But it is important to consult with the professional expert as to the details of cleaning job so as to take most suitable measures to the actual case and to prevent damage that may result otherwise.

4.7

Refractory As a refractory, castable type is applied. This refractory is often used for repairing work. When the castable refractory is to be used on the pressure parts, it should be given necessary clearances for thermal expansion. After repairing refractory work, never fail to dry it out by firing.


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K1D97-N57-10M-M501 4.

4.8


Boi ler Proper and Water Walls Inspect both gas and water sides of the boiler whenever the opportunity is afforded and see whether it is necessary or not to clean the gas side, to acid cleaning the water side or to replace tubes. Results of these inspections should be referred to in the subsequent burner operation, feed water control, etc.

4.9

Economizer By-pass operation using “Auxiliary Feed Water” line can be applied when economizer tubes are damaged. Faulty tubes shall be repair as earlier as possible. Note; Economizer by-pass operation is not applied to this project as project requirement.

4.10 Boil er Drum Support Legs The water drum support legs on the boiler rear side are the only fixed legs, and all the other legs are of sliding type requiring the injection of grease once a year. (Grease : Shell Alvania EP No.2, Mobilux EP No.2 or equivalent.).

4.11 Boiler Repair The boiler repair work includes the tube plugging, header end plate renewal, removal of manhole cover, tube renewal, expander renewal, packing renewal, etc. It is required that the boiler operator be familiar with the working procedures therein involved.

4.12 Maintenance of Accessories 4.12.1

Burner

The burner tip is to be cleaned periodically and examined for disorder. The swirler is to be maintained as clean as possible, and also the burner throat area is to be always kept in good working order.


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K1D97-N57-10M-M501 4.

4.12.2


Soot blo wer

The soot blower steam line drain discharge, smoothness of rotary motion, and adequacy of lubrication are to be monitored. In the process of boiler open-up inspection, the element nozzle is to be examined for disorder and also the element for bend.

The soot blower st eam line drain dis charge should be carried out before operation o f soot blower.

To make sure no steam leakage from soo t blow er mounted inl et valve into bl owing element.

4.11.3

Auto matic Combusti on Control System and Auto matic Feed Water Regul ator

By taking the control unit indicator reading, the control performance of each system is to be monitored. The air supply line drain is to be blown out every one week. The moving parts of every equipment are to be kept always clean or grease-up periodically for rust prevents purpose as necessary . Note; Burner management system is provided by Hamworhy Combustion, hence instruction details to check their instruction manuals.

4.11.4

Water Lev el Gauge The gauge glass is to be blow n clear at least once a day to ascertain its responsiveness. The remote-reading level gauge reading i s t o be compared with the gauge glass r eading (once a day) to ascertain its reliability.


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K1D97-N57-10M-M501 4.


4.12 Check Point Lis t

IMPORTANT The followings are to be checked periodically to operate boiler safely. Item

Check Method

Check Interval

Check Water level response at opening or Water Gauge

shutting blow valve.

Boiler, boiler casing, ducts etc.

Check no harmful vibration at boiler, casing, valves, ducts, piping, tubing, detecting lines or

1 / Day

pressure accessories related to the boiler.

Remote Water Level Indicator

Compare the remote water level indicator with transparent level indicator at 100 mm decreased

1 / 2 Weeks

water level below normal. Manually operate FWR.

Combustion condition and Flame Detector

Check combustion condition. And it’s normal condition to indicate burner flame failure to each

Burner Level

1 / Day

burner at only each burner firing.

Air Slide Operation of Close or open the air slide manually at boiler side.

Water

1 / Day

Alarm Check the water level alarm point, manually to operate FWR at boiler lower load.

Point

Fuel shut off valve for Check operation of each fuel shut off valves such as fuel oil shut off valve, fuel gas shut off valve

safety system

1 / 2 Week

1 / 3 Month

1 / 6 Month

Leakage of Steam or Inspect boiler pressure parts, water level gauge, flanges and valves.

Water

Inspection leakage and inside condition.

Fuel gas line

(Confirm no sulfur corrosion in BOG piping

expansion joint Sliding

surface

caused by combustion gas back flow.) of Check the condition of sliding surface and to

boiler and economizer make sure no harmful rust or scratch. Put make feet and valve stem

up grease periodically.

Casing / Insulation for

Check the condition of casings and to make sure

boiler,

economizer no harmful damages or no gaps between plates.

and duct

1 / week

1 / week

Note; Water ingress to protect by casings.

boiler, Check the condition of painting and touch up if required. economizer and duct Painting

1 / 2 Year

for

1 / week


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K1D97-N57-10M-M501 4.


4.18 Condi tio n of the Emergenc y Fuel Oil and Gas Cut Recommendation for custo mer only. Boiler is shut down by the condition as follows. Particular

Set Point

Location

Drum Level Low-Low

-240 mm

Local

Electric Source Failure

-

Local

Both B.M.S. Controller Abnormal

-

Local

Emergency Hand Trip Switch

-

ECR & Local

Over current

Starter

Flame Out

Local

4 bar

Local

Forced Draft Fan Stop All Burner Flame Failure Control Air Press. Low-Low

Remarks After 7 sec., off signal

After 0 sec, off signal

Emergency fuel oil shut off valve is shut down by the condition as follows. Particular Fuel Oil Pressure Low-Low Fuel Oil Temp. Low-Low Atom. Steam Press. Low-Low Fuel Oil Pump Stop Boiler Trip

Set Point

Location

1 bar

Local

n/a

n/a

3 bar

Local

No voltage

Starter

-

Local

Remarks

Emergench fuel gas cut valve is shut down by the condition as follows. Particular

Set Point

Location

Fuel Gas Pressure High-High

n/a

Local

Fuel Gas Pressure Low-Low

n/a

Local

Master Gas Valve Trip

-

Local

Boiler Trip

-

Local

Remarks

Emergency master gas valve is shut down by the condition as follows. Particular

Set Point

Location

Emergency Hand Trip Switch

-

ECR & Local

Gas Leak Detection

-

Local

Cargo Tank Pressure Low-Low

-

Local

5 deg.C

Local

Both Gas Duct Exhaust Fan Stop

-

Local

Both Boiler Trip

-

Local

Both Boiler Gas Valve Trip

-

Local

Fuel Gas Temp. Low-Low

Remarks


4-6

K1D97-N57-10M-M501 6. General Maintenance

5)

Place test clamps (gags) on all safety valves. Safety valves should never be opened by hydrostatic pressure.

6)

The pressure gage used should be checked, before applying the maximum test pressure.

7)

When filling the boiler open the vents on the boiler drum to bleed off all air, close the valve when water runs out.

8)

Before lowering the pressure, take up the slack on the nuts of the handhole and manhole fittings, were new gaskets have been fitted. The nuts should be pulled just snug with the wrenches supplied for the purpose. Do not use a pipe or other extension on the wrench handle.

9)

When inspection is completed, open the vent valves and lower the pressure slowly by cracking a drain valve. Use one of the bottom blow valve. Before starting to drain the boiler, be sure to open the vent valves.

10)

6.9

Remove the safety valve gags, replace the lifting levers and easing gear.

Boil ing Out If the presence of oil is found on the waterside of the boiler, it must be removed by boiling out. This is necessary after assembly of a new boiler, after completion of repairs requiring extensive replacement of tubes, or if oil has entered the feed water from some other source. Boiling out is also a quick and efficient method of removing various types of scale. The chemicals to be used and the strength of solution required, depends on the character of the scale. Consult the boiler water chemist. Boiling out to remove oil requires the use of a fairly strong caustic solution. One such solution is about 2 kg of caustic soda and about 4 kg of hydrated trisodium phosphate, for each 1,000 kg of cold water required to fill the boiler. This chemical solution is sufficient to remove ordinarily compounded lubricating oils or the usual protective oil coating applied to tubes before shipment. Straight mineral lubricating oils used for high temperature engines require stronger solutions. If such oil is present in the boiler use about 2 kg trisodium phosphate and about 5.5~6.5 kg caustic soda per 1,000 kg of water. In addition it is advisable to add detergent (wetting agent) amounting to about 0.5 % of the boiler water. There are other chemical solutions which can be used. There are many satisfactory compounds for boiling out, they are sold under various trade names by reputable firms. When such compounds are used, follow the manufactures instructions.

6.9.1

Steaming Method

Boiling out may be accomplished by injecting steam through temporary lines into the bottom blow. Temporary drip lines are connected to the boiler air vent and starting valve. The drip lines should be open drains to portable tanks or drums, which are used for inspection and measuring tanks. 1)

A chemical injector is used to inject the chemical solutions into the boiler, water wall as required. The chemicals are dissolved in water and injected into the boiler, water wall, in proportion to the weight of cold water required to fully fill each part. The water weights of each part are listed under "2.11 Design Data".


6-9


2)

After injecting the dissolved chemicals, slowly start admitting steam, allowing the condensate to fill the unit, until water overflows from the vents of the boiler.

3)

Then throttle the vents and steam injection valves to maintain a pressure of about 0.4 MPa on the unit, and to allow some overflow from vent. Regulate the vent valve so that the overflow is roughly in proportion to the weight of water of each part of the unit.

4)

The progress of boiling out can be determined by examination of samples from the drip lines. Check the alkalinity of the samples, and inject additional chemical solution as needed, to maintain a satisfactory strength of the solution. Continue boiling out until no trace of oil can be found in the samples taken from the drip lines.

6.9.2

Firing Metho d

If steam and electric power are available and the auxiliaries are ready for service a boiler can be boiled out using a light fire. When the firing method can be used, it is much simpler and does not require temporary piping. The same chemical solution is used as described in the preceding method. The quantity of solution to use should be figured for the weight of cold water required to fill the boiler to normal steaming level. (See "2.11 Design Data".) 1)

Make certain that no personnel are in the drum or in the furnace.

2)

After filling some water, about half amount of chemicals shall be admitted into the water drum. Manhole shall be closed and the boiler shall be filled the water again. Solid chemicals should be dissolved with water before admitted.

3)

When the boiler water has been filled in the steam drum to some degree, rest chemicals shall be admitted into it through manhole.

4)

When necessary amount of chemicals has been admitted into the drum, manhole shall be closed and the boiler shall be filled up to the normal water level.

5)

Using one burner, burner shall be fired at 0.3 MPa of oil pressure for about 5 minutes at rest about 10 minutes interval. After repeated 2 hours, then burner shall be fired again for 10 minutes at rest 5 minutes interval. It is to avoid for burning of refractory and rapid thermal expansion. The boiler shall be fired at a rate to start steaming in about 2 hours. MGO shall be used with air atomizing. Valve operation during pressure raising, refer to “5.2 Starting a Boiler from Dead Ship Conditions”.

6)

Boiler pressure shall be raised slowly to reach about 1.4 MPa after 4 hours of oil burning.

7)

Boiler pressure shall be maintained at 1.4 MPa during the soda-boiling period.

8)

When oil content of boiler water can not be measured, soda-boiling shall be continued for 8 hours. When oil content of boiler water can be measured, after holding the boiler for 3 hours at soda-boiling pressure of 1.4 MPa, sample of boiler water shall be taken at every 1 hour to be checked of its alkaline strength and oil content. If the oil content of the sample water has become to show no more increase at each measurement, that is, when no further operation of soda-boiling is thought necessary, soda-boiling can be terminated even before 8 hours have passed.


6-10


9)

If the water level gauge is fouled with oil in soda-boiling operation, it shall be cleaned by blowing steam by closing water-side root valve and opening drain valve of the gauge.

6.9.3

Wash and Insp ect

1)

After boiling out is completed, by either the steaming of firing method, blow down the boiler through the water drum bottom blow off valve while the boiler is fairly warm. Discharge the water overboard, to avoid damaging paint in the bilge by the strong caustic solution.

2)

Open up the boiler and wash down with a high pressure water hose, playing the hose into all tubes.

3)

Carefully inspect the boiler, and if any trace of oil remains, repeat the boiling out process.

6.10 Water Washin g Fireside The heavy oil is the last extracted fuel oil in the refining process of crude oil, therefore includes the ingredients causing slag on the gas side surface, and also is apt to includes the component of the sea water due to marine transportation which promotes the slag accumulation in the boiler. Slag is a mixture composed of sodium sulfate or a mixture of sodium sulfate and vanadium pentoxide, and lesser amounts of the oxides of other impurities. When burners are kept in proper adjustment, the atomizer kept clean and in good condition, and the soot blowers operated at correct intervals, slag formation may be slowed down. However slag formation will eventually accumulate on the tubes and should be removed before it has bridged over between tubes. Water washing schedule should be set up to coincide with normal fireside cleaning. Operating practice will indicate at what intervals of fireside cleanings water washing is necessary. Since slag is soluble in hot fresh water, hot fresh water is sprayed on the slag encrusted tubes with a lance, using sufficient force to soften the slag and knock it off the tubes. There are two methods in water washing. One is to use a hand nozzle and the other is to utilize the soot blower in spraying hot water. The former permits concentrated washing of important points so that effective washing can be done with relatively small quantity of water resulting in less moisture of the boiler; but much time and labor is required. With the latter, washing can be done easily in a short space of time but it requires relatively much water resulting in larger moisture of the boiler. Water washing is usually carried out at a dock. A member of the crew can do it quite easily. If preparation has been made in advance while the boiler is cooling, water washing will be done in 6 8 hours although it depends on the extent of dirtiness. The following is the order to processes of

～

water washing with a hand nozzle. 1)

Prepare an apparatus to supply adequate quantity of hot water and a hose and nozzle for spouting hot water.

2)

Remove the casing access doors and dusting panels to facilitate the work.

3)

Provide a means for immediate and constant draining of the waters and the removal of the sludge, resulting from washing down.

4)

Water under 1.8 MPa and at a temperature of about. 65

90degC should be sprayed on to the

～


6-11


tubes, using an armored hose. Work from the top of the boiler down. In cases where slag removal is extremely difficult, secure from washing, and allow the water to soak into the slag for a period of 30 minutes to one hour. Then continue washing down the tubes. 5)

Attention should be paid not to let washing water penetrate behind the bricks. It will be effective to lay a sheet of canvas on the furnace floor. If small quantity of water is absorbed by bricks and heat insulating materials, the bad effect will be removed by slowly drying soon after the finish or washing.

6)

It is desirable that the water washing is finished within 8 hours.

7)

As soon as possible after washing is completed, light up the boiler, using one burner at a time. The drying out operation should be done very slowly and should be continued until the boiler is thoroughly dried out. The drying should be made at least for 12 hours.

Atten ti on sh ou ld be paid no t t o let w ashin g w ater penetr ate behi nd the bricks.

6.11 Ac id Cleanin g 6.11.1

Introduction

Safe and efficient methods of cleaning boilers by acid washing have been developed to remove scale. This work should be done by contractors having experienced and competent personnel with proper equipment. The following information is herewith presented for the general information of the operator. This discussion will be limited to the cleaning of the boiler circuits. The following should be supplied: 1)

An acid filling tank of sufficient capacity to hold the prescribed amount of acid and inhibitor.

2)

One centrifugal acid filling and circulating pump with bronze impeller designed to deliver a minimum of from 0.2

3

0.4 m /min at 35 mTH or of such capacity as to fill the unit in not more

～

than 2 hours. 3)

Suitable temporary piping and fittings to connect both the pump and tank to the boiler.

4)

Cleaning chemicals. A typical cleaning solution would contain 28

34 % hydrochloric (muriatic) acid, an inhibitor and

～

water. The amount of acid used would be roughly 10

20 % by volume of water necessary to fill

～

the component to be cleaned. See "Design Data. Selection of the concentration of acid used (1 6 % by weight for any one unit) depends upon the type and amount of scale or rust and other

～

impurities to be removed. Special attention must be given to ensure that the acid solution is not enriched by ferric or cupric ion, which can be caused from the removed scale or deposits containing a large portion of ferric or cupric oxide. This will impair the effect of the inhibitor. In such a condition, keep the acid solution below the maximum allowable concentration of ferric or cupric ion, by adding or renewing the reducing agent. MHI-MME Proprietary Information

6-12


6.11.2 1)

Procedure If more than a trace of oil is found in the boiler, it must first be boiled out with an alkaline solution. A boiling out period of from 6

2)

10 hours in adequate, when followed by acid cleaning.

～

Remove all tools, rags and other foreign material from the waterside of the boiler. Secure all handhole plates, the manhole plates and valves, that will make the boiler watertight and isolated from all boiler accessories except the water gauges.

3)

Extension should be connected to the highest vents in the boiler, to ensure safe removal of hydrogen gas, generated during the acid cleaning. Allow no welding during the acid cleaning process.

4)

Temporary piping should be connected from the filling tank to the filling pump suction, and from the filling pump discharge to the lower water wall header drains. Piping should also be connected from the most convenient steam drum connection to the filling tank.

5)

Start filling the boiler with water 65

90degC. While the feed water is being injected into boiler

～

through the regular feed system, start pumping the acid and inhibitor into the boiler through the water wall header drains. If all the acid has not been pumped into the boiler by the time the water shows in the gauge glass, secure feeding the boiler, until all the acid has been injected into the boiler. 6)

When all of the acid has been injected into the boiler continue to fill with water until the level in the steam drum is high enough to cover all tubes to be cleaned. The tubes must be covered to permit thermal circulation.

7)

If it is desired to acid clean the entire drum completely fill the unit, adding acid in the same proportions as before.

8)

Run the circulating pumps 3

5 minutes each hour. If it is found that a wide temperature spread

～

exists between various parts of the boiler or if the scale deposit is excessive, use a half hour cycle. 9)

Check test samples of the cleaning solution with a standard sodium hydroxide solution and methyl orange indicator. The value of this depends upon being able to get a true representative sample. The acid concentration should be tested at the end of each circulation period. When the concentration has leveled off, and remains constant over two successive tests the dissolution can be considered complete.

10)

Empty the boiler through the skin valve using compressed air.

11)

Average acid contact time should be from 6

8 hours. If the scale has not been removed during

～

this period, the probable cause is:

6.11.3 1)

a)

Weak solution; repeat process.

b)

Misidentified scale and wrong solution used, high in silicates, sulfates or oil.

General Precaut io ns Before injecting the acid solution into the boiler it is good practice to check the effectiveness of the inhibitor. A weak inhibitor will permit excessive corrosion of the boiler metal.


6-13


2)

A quick check of inhibitor consists of diluting the concentrated acid to approximately 5 %, then drop in a piece of cold rolled steel in the solution and heat to 65degC. Well mixed inhibited acid produces very few hydrogen bubbles which should be small and difficult to see. For comparison run a test with uninhibited acid.

3)

Check the metal temperatures particularly the steam drum before injecting acid, before and during each pumping operation. This can be done by using thermocouples located at critical points or by contact pyrometer. It should be noted that THE TEMPERATURE IS A MOST CRITICAL FACTOR in the procedure. Too low a temperature, under 50degC will result in poor dissolution of most deposits. Too high a temperature, more than 80degC for most inhibitors, will increase the corrosion rate appreciably, if not to a damaging degree. Stay within the temperature limits prescribed by the manufacturer of the inhibitor. If there is any doubt, stay under a temperature of 65 degC.

4)

After draining out the acid, wash down the boiler with fresh water, using the same washing process as described after boiling out.

5)

The boiler should be boiled out with an alkaline solution (See Boiling Out). This is to both clean the boiler of suspended particles and to return all surfaces to an alkaline base.

6)

After boiling out, wash the boiler with a strong steam of hot fresh water with a hose.

7)

After acid cleaning DO NOT ENTER OR WORK in the boiler until it has been filled at least once with water, and preferably after the boiling out process.

6.12 Mechanical Waterside Cleaning Whenever a boiler is opened, hose down accessible parts of the waterside. Water washing should not be substituted for mechanical cleaning when latter is required.

6.12.1

Cleanin g of Drums and Headers

nternals should be inspected whenever boilers are secured. Internal fittings should be removed from the drum as necessary. Internal fittings should be carefully marked and identified as to position in the drum to insure proper reinstallation. When above inspection indicates need for it, proceed with a thorough wire brushing of all tubes and drums. The boiler should then be blown out thoroughly with air, followed by washing out with water. Dry the boiler out and explore random tubes in all parts of the boiler with a power wire brush. If dirty, repeat the cleaning process specified above.


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K1D97 N57-10M-M501

K1D97 N57-10M-M501

K1D97 N57-10M-M501

K1D97 N57-10M-M501

K1D97 N57-10M-M501

K1D97 N57-10M-M501

K1D97 N57-10M-M501

MAC Boiler Manual (Extract)

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