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Process heating :New Technology .

R. S. Jha

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Key drivers for the innovation.

• Efficiency

• Emission

• Reduction in carbon foot print

• Compactness

• Life cycle cost

• Serviceability & maintainability

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Fossil fuel : Combustion technology

• Classification of combustion technology-

*Grate combustion

- Stationary grate

- Travelling grate

- Reciprocating grate

*Fluidised bed combustion

*Dust combustion

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Biomass : An alternative fuel

• Challenges in biomass combustion-

*Fuel with low density, higher moisture level and

low calorific value- difficulty in handling.

*Inconsistent supply of fuel & seasonal variation

in fuel properties – Boiler should be designed

with fuel flexibility

*Higher level of emission

*Slagging & fouling

• Need of an appropriate combustion technology

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Thermax Lambion combustion technology

Inclined reciprocating grate

Horizontal reciprocating grate

Combined reciprocating grate is

being developed.

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Combloc- A packaged biomass

boiler

A Packaged

biomass boiler

with horizontal

reciprocating

grate

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CPRG- A biomass boiler with inclined

grate

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Future of combustion technology

• Gasification

• Oxyfuel combustion

• Unmixed combustion

• Chemical looping combustion

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Development in the boiler design

• Boiler development- Size, fuel flexibility,

emission & efficiency

• Development in combustion technology

• Heat transfer enhancement- Tube inserts

& special tubes

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TEON 300

SIBR,7Kg/cm²

TEON 500

SIBR 7

Kg/cm²

TEON 750

IBR 7

Kg/cm²

TEON 1000

IBR,

10.54Kg/cm

²

TEON 1500

IBR 10.54

Kg/cm²

Thermeon – A compact

boiler

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Fluegas heat recovery

• Conventional heat recovery technology

*Feed water preheating

*Combustion air preheating

• Challenges

*Economics of heat recovery

*Low end corrosion

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Need for condensing technology.

• Flue gas still contains approximately 6-8 % heat of the net calorific value of the fuel.

• Natural gas has a significant portion of hydrogen, which gets converted in to water vapour after the combustion. In the process of combustion, a significant portion of the heat is lost to provide the required latent heat for the evaporation of water. If we consider this heat, approximately 15-17 % heat is still left with the flue gas. This can be easily explained by noting the difference of efficiency on the basis of GCV and NCV. Even with conventional heat recovery system, the efficiency on the basis of GCV is in the range of 83-85 %.

• If the condensation of water vapour of the flue gas is allowed, flue gas temperature can be further reduced to maximise the boiler efficiency.

• This opens a significant opportunity for the flue gas heat recovery, as the latent heat of condensation is recovered in the process of condensation. If the sufficient heat sink is available and system is optimally designed, approximately 10-12 % heat can be recovered higher than the sensible heat left with the flue gas (6-8 % of the NCV).

• If we consider efficiency on the basis of NCV, the efficiency of boiler can go beyond 100%. Using condensing technology, The latent heat of water vapour is received back, which was considered as lost in the definition of Net calorific value.

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Challenges :Condensing technology.

• Criticality of material selection- Material selection is very critical for the design and selection of the condensing heat exchanger. The suitable material should be anti corrosive to deal with acidic condensate. Material should have higher thermal conductivity and non sticky.

• Chimney corrosion- Other challenge of the condensing heat exchanger design is the problem of chimney corrosion.

• Higher cost- Due to poor heat transfer performance and the special metallurgy, the cost of condensing exchanger system is normally high.

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Efficient method of steam utilisation

• Focus on system efficiency- Closed loop

system & open loop system

• Combined heat & power

• Process integration

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Aquaerotherm- Integral air heater

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Use of computational

technology for new

development

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CFD- Computational fluid dynamics

Higher stack temperature problem of

thermal oil heater has been analysed

and solved by using CFD.

Flo

w m

al d

istrib

utio

n

iden

tified a

nd

corre

cte

d fo

r oil fire

d

fire tu

be b

oile

r.

CFD helped to develop new

correlation for the heat transfer

coefficient of the coil type heater.

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FEA- Finite element analysis.

*FEA has served as a major

tools for design and

development of many new

product,

*It has also helped to

identify and solve some of

the chronic problem.

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Innovation cont…