Boiler using Biomass as Fuel - pumpsandvalves-asia.com. Asst... · Rice husk (RH) Rice field in...

Boiler using Biomass as Fuel

Director of Renewable Energy and New Energy Technologies ProgramNational Science and Technology Development Agency (NSTDA)

Bio‐Energy: Pretreatment, Combustion and Pyrolysis of Biomass 16 June 2018, BITEC, Bangkok, Thailand

International Conference “The Future of ASEAN’S Energy Journey E‐mobility – Smart Grid – Smart City”6 June 2018, BITEC, Bangkok, Thailand

Suthum PATUMSAWADDepartment of Mechanical EngineeringFaculty of EngineeringKing Mongkut’s University of Technology North Bangkok (KMUTNB)

26 June 2018, BITEC, Bangkok, Thailand Bio‐Energy: Pretreatment, Combustion and Pyrolysis of Biomass

Outlines of Presentation

General Description of Boilers Biomass Fuel Opportunity Technical Barriers Choosing the right Fuel? The need of Biomass Characterisation Concluding Remarks

General Description of Boilers

6 June 2018, BITEC, Bangkok, Thailand Bio‐Energy: Pretreatment, Combustion and Pyrolysis of Biomass 3

A boiler (or steam generator) consists of a fossil fuels or biomass burner and a heat-transfer system to boil water and generate steam. Steam generators also include systems and components for pressure control, heat recovery, steam delivery and distribution, condensate drainage, and separation of oxygen and non-condensable gases.


Use of Boilers

o Electrical generationo Chemical industryo Petroleum industryo Pulp & paper industryo Food industryo Etc.


Biomass Fuel Opportunity

o Addresses key energy, economic, environmental and social problems at the local and global scale

Biomass fuel is :• Regenerative EnergyPlants continue to grow as long as existence of sun light, water and soil. Efficient use of biomass energy is applauded as fossil fuels become depleted.Agro-forestry wastes previously disposed of are recovered as fuel energy. This forms a recycling type community with reduced waste generation and efficient energy use• Earth-friendly EnergyPlants absorb CO2 in the growing process. Rich, green forests thus help prevent global warming.


Biomass Fuel Opportunity

Power generation from biomass can be achieved with a wide range of feedstock which have different properties.


Biomass Characteristics

• Lower density

• Higher moisture content, often up to 50%

• Lower calorific value

• Broader size distribution, unless pre-conditioned by screening, crushing or pelletising

• The variability of the material as a fuel will be greater


Biomass differs from conventional fossil fuels

• Physical structure

• Chemical structure

• Moisture content

Therefore it must be burnt differently.

Technical barriers

Effect of Moisture• Decreases combustion temperature• Leads to incomplete combustion

higher CO and Carbon in Ash• Decreases boiler efficiency• Leads to more fuel use, higher

energy costs and increased air pollutants


Biomass Fuel - Volatiles

• 70 – 80% of dry biomass is “volatile” hydrocarbons.

• Released from the biomass structure at relatively low temperatures.

• Volatiles burn in “suspension” way from the biomass particles.

• Balance is “fixed carbon” or “char”.


Biomass Fuel - Ash


Biomass Fuel - Ash

• Combines with alumina and silica lowers melting point

• Slagging on grate and boiler tubes

• Ash accumulation Airflow problems High draft losses Reduced heat transfer Boiler shutdowns


Biomass Fuel - Ash

• Agglomeration and Sintering problems

• Fouling and Slagging problems

• Corrosion and Erosion problems


Choosing the right fuel?

Prior to design combustion system, answers to the following questions must be known:

Is the biomass which will be used apt for combustion system? What are the optimal conditions for the combustion of the specific biomass? What is the range of biomass which may be used in the specific combustion system?


The need ofBiomass Characterisation

Quality of biomass fuel is the most important point for the reliability of the plantAvoid ContaminantsControl moisture contentChemical analysis is critical to understanding of performance

The lack of sufficient information concerning biomass feeding as well as the combustion and emission characteristics of biomass.

This information is important for the design and efficient operation of combustion systems


The need of Biomass Characterisation

Useful important for the design and efficient operation of combustion systems

Biomass characterization• Identifies the fuel value• Provides an estimate of ash handling requirement• Describes something of the burning characteristics• Indicative of problems arising during combustion


Some outputs: Fuel property analyses

Fuel sample Source

1. Lignite Coal (Lig) Thai lignite company, Lampang

2. Sub-bituminous Coal (SB) Asia Green company

3. Rice husk (RH) Rice field in Nakornphatom

4. Rice straw (RS) Rice field in Nakornphatom

5. Giant Leuceana Wood

(LW)Mitr Phol Group, Suphanburi

6. Eucalyptus Wood (EW) Asia charcoal company

7. Napier Grass (NP) Farm in Kanchanaburi

8. Palm empty fruit bunch

(EFB)

Suksomboon oil plam company,

Chonburi

9. Sugarcane Top and Leaf

(CT/L)Mitr Phol Group, Suphanburi

10. Sugarcane Leave (CL) Mitr Phol Group, Suphanburi

11. Wastewater sludge (Slud) Samutsakorn Industrial estate

Table 1. Fuel sample used in this study Fuel Properties Testing method

1. Proximate analysis

- Volatile matter

- Fixed carbon

- Ash (at 900OC)

ASTM D 5142 by TGA

2. Ultimate analysis

C, H, N, S, O

Organic elemental analyzer

(OEA)

3. Moisture content (%ar) ASTM D3173

4. Gross Heating Value Bomb Calorimeter

5. Ash content ASTM E1755 at 575OC

6. Chemical structure

- Hemicellulose

- Cellulose

- Lignin

TAPPI T203om-88

TAPPI T204 om-88

TAPPI T222 om-88

TAPPI T223 cm-01

(biomass only)

7. Ash composition XRF, XRD

8. Ash Fusion Temperature

(AFT) for coal only

Oxidation by air, Reduction

by CO/CO2 60/40 (v/v)

Table 2. Fuel properties and testing method11 fuel samples: 2 coals, 8 biomasses and 1 wastewater sludge



0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Proximate analysis (dry basis, wt%)

Fixed carbon VM ash

Fuel Moisture

(wt%, ar)

HHV

(MJ/kg dry)

1. Lig 11.9 17.22

2. SB 9.4 20.85

3. RH 9.7 14.30

4. RS 10.1 15.37

5. LW 17.1 12.75

6. EW 13.4 16.57

7. NP 9.5 15.62

8. EFB 9.5 17.28

9. CT/L 8.6 16.11

10. CL 9.9 16.53

11. Slud 11.0 9.73

Table 3. Moisture content and HHV

Figure 1. Proximate analysis of the fuel samples


Sample SiO2 Al2O3 SO3 CaO Fe2O3 MgO K2O Na2O MnO P2O5 Cl BaO TiO2 SrO Rb2O ZnO CuO Cr2O3 SnO2Sludge 9.02 19.86 12.44 34.91 5.93 1.44 0.68 1.37 0.11 7.07 0.29 0.22 3.08 2.99 0.46 0.12

Lignite 25.95 17.73 19.64 17.23 12.42 2.84 1.70 0.76 0.00 0.11 0.00 0.76 0.62 0.24

SB 23.78 17.16 13.04 12.54 25.59 4.28 1.23 0.59 0.48 0.18 0.00 0.00 0.96 0.15

NP 48.63 0.36 2.45 3.07 0 11.15 20.86 0.46 0 6.20 6.82

LW 6.52 1.76 4.95 40.69 3.86 7.09 28.76 1.32 0.45 3.09 0.52

CT/L 30.67 0.27 10.93 15.94 0.48 5.08 27.97 0.24 0.63 5.9 2.59 0.11

EW 1.43 0.92 8.30 5.99 0.80 10.37 34.85 1.65 1.49 14.20 0

EFB 11.65 0.31 2.65 12.46 4.72 3.42 56.45 0.29 0.27 4.13 3.47 0.18

RS 73.85 0.76 2.36 3.62 0 4.36 9.62 1.19 0.28 2.04 1.91

RH 93.83 0.07 0.39 0.91 0.78 0.35 2.74 0.04 0.18 0.52 0 0.07

Table 4. Ash composition of fuel sample by XRF (%wt dry ash)

- The major elements in both coals were Si, Al, Ca, Fe and also high in SO3

- NP, CT/L, RS, and EFB were high in both K and Cl and therefore likely to have ash

related problems

- Slud was high in Al, Ca and also high in Si and SO3



BiomassChemical Structure (%wt, dry biomass)

Cellulose a Lignin b Hemicellulose c Extractives d

Rice husk (RH) 40.17 29.03 29.40 2.03

Rice straw (RS) 37.425 27.27 27.64 5.47

Leuceana Wood (LW) 31.58 31.60 23.37 1.89

Eucalyptus Wood (EW) 37.448 28.64 30.19 1.14

Napier Grass (NP) 36.438 24.70 30.82 5.28

Empty fruit bunch (EFB) 27.63 29.34 21.80 21.23

Cane Top and Leave (CT/L) 34.69 22.97 29.58 12.76

a TAPPI T203 om-88 (1992). “Alpha, beta, gramma cellulose in pulp” , b TAPPI T222 om-88 (1988). “Acid-insoluble lignin in wood and pulp”c TAPPI T223 cm-01 (2001). “Pentosans in wood and pulp” , d TAPPI T204 om-88 (1997). “Solvent extractives of wood and pulp”

Table 5. Chemical structure of biomass samples



Coal Atmosphere

Temperature (OC)

Initial

Deformation

Spherical

Temperature

Hemispherical

Temperature

Flow

Temperature

Lignite Reduction

(CO/CO2, 60/40 %v/v)

1,190 1,210 1,230 1,230

Oxidation (Air) 1,250 1,260 1,280 1,290

SB coal Reduction

(CO/CO2, 60/40 %v/v)

1,130 1,160 1,190 1,220

Oxidation (Air) 1,190 1,220 1,230 1,250

• Coals had relatively low IDT, especially under reducing atmosphere



Combustion characteristic of Single Fuels (example curves)

• Coal exhibited a one-step combustion, two-step

combustion (devolatilization followed by char

combustion) was clearly observed for biomass (incl.

sludge).

• Decomposition of biomass started at lower temperature

than coal was due to the higher VM content.

Figure 2. TG and DTG curve of single fuel combustion

Some outputs: Combustion characteristic of fuel


Combustion characteristic of blend Fuels

Example 1: Lig/RS blends

Pure RS

Pure Lig

Pure RS

Pure Lig

Figure 3. TG curves of combustion of Lig/RS blends

Figure 4. DTG curves of combustion of Lig/RS blends

• Combustion behavior of the blends clearly presents the behaviour of individual

components that is the prior decomposition of biomass followed by that of coal.

Some outputs: Combustion characteristic of fuel


Some outputs: Fouling tendency of fuel combustion


Morphology of deposit (1000X)

Pure RS SB/RS (1:1)

Pure NP SB/NP (1:1)

Pure EFB

SB/EFB (1:1)

Pure CTLSB/CTL (1:1)

• Morphology of deposit

from co-combustion was

drastically changed into

the melted surfaces, in

particular SB/RS and

SB/NP

Pure SB

Deposit Bottom ash

Some outputs: Fouling tendency of fuel combustion


Some outputs: Simulation of fuel combustion


Concluding Remarks

Although combustion technologies can already be considered as proven, there is a continuous demand for equipment with: Lower investment and operational cost Increased fuel flexibility Lower emissions Increased reliability and efficiency

Thank You

National Science and Technology Development Agency (NSTDA)

111Thailand Science Park Phahonyothin RoadKlong Nueng, Klong LuangPathum Thani 12120Thailand

Email: [email protected]


Boiler using Biomass as Fuel - pumpsandvalves-asia.com. Asst... · Rice husk (RH) Rice field in...

Documents

Transcript of Boiler using Biomass as Fuel - pumpsandvalves-asia.com. Asst... · Rice husk (RH) Rice field in...