AVANT-GARDE

Growth

1990 Inception

2017

27 Years of

distinguished

Engineering

Services

Group

Avant-Garde Systems and Controls (P) Ltd

Avant-Garde Projects and Infra (P) Ltd

Avant-Garde Engineers & Consultants FZC, Sharjah

Avant-Garde Engineers and Consultants (P) Ltd Consultancy and

Detailed Engineering

Services

Supply of Power

Plant Equipment,

Site Services, O&M,

Plant Revamping

Infra Projects

Consultancy and Detailed

Engineering Services

for Overseas Projects

Quality Assurance and Accreditation

ISO 9001 : 2015 ISO 17020 : 2012 CDC

Staffing

0

5

10

15

20

25

30

35

40

Mechanical

Civil & Structural

Material Handling

Thermal Design

Piping

Electrical & Instrumentation

Process EngineeringProject Management

Quality / Inspection

Site Services

Business Development

Administration & Accounts

Software Development

200+

Workforce

40,320 Engg

Man-hours /

Month

7,000 Man-

hours / Month

- Job

shopping

Memberships & Associations

Present Area of Business

Solar Plants

Co-Generation Plants

Sugar Plants

Distillery/Ethanol Plants

Power Plants

IPP, CPP, Biomass,

Co-Gen, MSW,

WHRSG, DG, GTG

PV, CSP

Bagasse, Coal, SLOP Fired

Molasses, Grain

Sweet Sorghum

Boiler Design

Grate Boiler, AFBC,

WHRSG

Raw Sugar, Plantation

White, Refined Sugar

Overall Power Projects

S. No Description Completed Under Implementation

Nos Capacity Nos Capacity

1 Captive Power Plants 66 1828.75 MW 37 1344.08 MW

2 Cogeneration Plants 99 2165.71 MW 55 1342.90 MW

3 Biomass Power Plants 49 464.10 MW 7 89.50 MW

4 Steel / Sponge Iron

Captive Power Plants 22 428.50 MW 34 1003.50 MW

5 Solar Power Plants 43 610.00 MW 13 430.00 MW

WtE Projects

• Two (2) projects have been commissioned to a cumulative capacity of 30 MW

• Detailed Project Report (DPR) has been completed for eleven (11) projects

Projects in 40 Countries & More

AVANT-GARDE

ENGINEERS AND CONSULTANTS (P) LTD

STEAM AND WATER

CYCLE IN WTE PLANT

Presented By:

J. Gladstone Evans

(HOD – Thermal Department)

AGENDA

• Introduction on Water and steam Cycle

• Rankine Cycle and Efficiency Improvement

• Selection Of Water and Steam Cycle Parameter in WTE Plants

• Typical Heat and Mass Balance Diagram for a WTE Plant.

• Water and Steam Cycle Heat rate and Plant Efficiency Calculation

• Questions & Discussions

Introduction on Water and

steam Cycle

INTRODUCTION

• WATER & STEAM is viewed as a Thermodynamic fluid,

which is well favoured for Power Generation and Heat

Transfer. It captures the energy released from the fuel and

convert it to another form of energy. (Chemical to Thermal,

Thermal to Mechanical and Mechanical to Electrical)

• The way in which the energy conversion occurs from one

form to another is referred to as process.

• A cycle is a sequence of processes that is capable of

producing net heat flow or work when placed between an

energy source and energy sink

ENERGY CONVERSION

• Chemical energy in the fuel is converted in to Heat Energy

• Heat Energy liberated from the fuel is converted to Thermal Energy (Water is converted to steam)

• Thermal Energy is converted in to Mechanical energy (Rotation of the turbine rotor)

ENERGY CONVERSION

• Mechanical energy is converted to Electrical energy by means of generator

PROCESS & EQUIPMENTS INVOLVED IN THE POWER CYCLE

• Process – 1: Water to steam in Steam generator ( 2 – 3)

• Process – 2: Steam is expanded in steam turbine (3 - 4)

• Process – 3: Steam is condensed in a condenser (4 – 1)

• Process – 4: Condensate

is circulated / Pumped back to the boiler (1 – 2)

2 3

4 1

WATER AND STEAM AS A WORKING MEDIUM

• Water & Steam is an Excellent resource for Mankind and the preference of water & steam as the working medium for power plants is due to – Wide Availability and Non Toxic nature. – Non Corrosive nature. – Inert System – High Heat Capacity (Specific heat). – High Critical Temperature. – High latent heat. – Excellent heat transfer characteristics – Has a well known property

Rankine Cycle and Efficiency

Improvement

WATER AND STEAM CYCLE (RANKINE CYCLE)

TYPES OF RANKINE CYCLE

• Simple Cycle

• Regenerative Cycle

• With One De-aerator

• With One De-aerator + LP Heater & HP heaters

• Re-Heat Cycle

• Supercritical Cycle

SIMPLE RANKINE CYCLE The basic elements of the cycle are the Boiler, Turbine the Condenser and the Feed Water Pump. While the boiler adds heat to the working medium and the unavailable heat is rejected in the condenser.

RE-GENERATIVE RANKINE CYCLE

Part of the steam from the turbine is

withdrawn in stages to heat the

condensate from the condenser. The

latent heat of the bled steam goes

back to the boiler, instead of going

out as heat rejected.

The basic elements of the

cycle are the boiler, Turbine

the condenser, the feed water

pump and the feed water

heaters. The heaters heat the

feed water to the boiler, using

bled steam. With One De-aerator

RE-GENERATIVE RANKINE CYCLE

Most of the present steam

based power plants uses a

combination of Open and

closed feed water heaters.

(One De-aerator + One or

Two LP heaters + One or

Two HP Heaters)

More the number of

heaters, the power cycle

efficiency increases.

Higher the feed water inlet

temperature to boiler, the

cycle efficiency increases. With One De-aerator and with HP & LP Heaters

RE-HEAT RANKINE CYCLE

The working medium is

Superheated Steam at the inlet of the

turbine. After expansion in the HP

Turbine, the exhaust steam is

reheated in the boiler and is injected

in the LP turbine.

The basic elements of the

cycle are the boiler (with

Superheater & Re-heater),

Turbine the condenser and the

feed water pump.

SUPER CRITICAL RANKINE CYCLE

Today many modern power plants

operate at a supercritical pressures

(Above 221ata).

HOW TO INCREASE THE RANKINE CYCLE EFFICIENCY

• Decrease the Condenser

Pressure ( P2, P1 )

• Increase in the steam cycle

Temperature ( T3)

• Increase in the steam cycle

pressure ( P2, P3)

• Increase the steam pressure &

Temperature ( P2, P3 & T3)

CONDENSER PRESSURE

• The turbine exhaust parameter depends on the ambient conditions and water availability.

• Normal Operating range 0.22ata to 0.09ata – ACC (0.22 to 0.16ata), which

depends on the ambient temperature.

– WCC (0.12 to 0.09ata), which depends on the wet bulb temperature.

• Present trend is towards Air Cooling system.

0.22ata

• 1.0TPH of steam when expanded from 45ata & 440°C to

• 213kW

0.18ata • 219kW

0.14ata • 226kW

0.10ata • 235kW

STEAM INLET TEMPERATURE AND PRESSURE

With the inlet pressure increase, the

increase in the available energy is

marginal, but there is a net increase as the

slope of condenser pressure line is

comparatively more.

Effect of increasing inlet temperature

keeping pressure constant. Available

energy increases as slope of pressure

line is more than condenser pressure

line.

STEAM INLET PRESSURE AND TEMPERATURE

215 235

260 275 285

0

50

100

150

200

250

300

35

ata

&3

80

°C

45

ata

&4

40

°C

67

ata

&4

85

°C

87

ata

&5

15

°C

11

0at

a &

54

0°CP

ow

er

Ou

tpu

t (k

W)/

TPH

of

ste

am (

Un

de

r fu

ll c

on

de

nsi

ng

mo

de

)

Selection Of Water and Steam

Cycle Parameter in WTE Plants

HISTROY OF STEAM CYCLE PRESSURE

• There is a gradual increase in the power cycle parameters across the globe

• Today there are many small capacity power plants operating at 87ata and 110ata.

• We are presently marching towards 125ata & 145ata Plants.

• However, WTE power plants normally operate a power cycle levels of 45ata.

35ata

45ata

67ata

87ata 110ata

215 235

260 275 285

0

50

100

150

200

250

300

35

ata

& 3

80°

C

45

ata

& 4

40°

C

67

ata

& 4

85°

C

87

ata

& 5

15°

C

11

0at

a &

54

0°C

Po

wer

Ou

tpu

t (k

W)/

TPH

of

stea

m

(Un

der

fu

ll c

on

den

sin

g m

od

e)

SELECTION BASIS FOR POWER CYCLE PARAMETER

• Capacity of Power Plant

• Type of Power Plant

• Characteristics of Fuels and ash

• Operation with the existing Facility

• Initial Investment

• Limitation in the technology

FUEL & ASH CHARECTERISTICS - MSW Indian Coal Bagasse Rice Husk MSW

SiO2 55-65 40-55 80 -92 45-60

Fe2O3 03-06 03-08 01 - 03 03-12

Al2O3 08-20 05 - 10 00-05 06-12

CaO 01-03 05 - 08 02-04 07-16

MgO 01-02 01 - 04 Traces 01-02

Na2O 00-01 00-02 00-01 02-15

K2O 00-01 00-08 00-03 05-20

SO3 00-03 Traces Traces 00-05

P2O5 00-02 01 - 04 Traces 10 -25

Cl 00-0.1 Nil Nil 00-02

IDT 1400 1100 1400 700 - 800

High Percentage of Fe2O3, Na2O, K2O & Cl makes the fuel, a very high fouling, slagging and corrosive nature

POWER CYCLE PARAMETER FOR WTE PLANT

• Corrosion due to Hydrochlorides (HCl) in the combustion gas

• Corrosion due to NaCl and KCl deposits on the tube surface

• Corrosion due to Low melting point metal chlorides (ZnCl2 & PbCl2)

• Corrosion due to wet salts on the tube surface

CORROSION CHART – MSW APPLICATION

0

100

200

300

400

500

600

500 C 600 C 700 C 800 C 900 C 1000 C

Tub

e M

eta

l Te

mp

era

ture

Flue Gas Temperature (Deg.C)

Severe Corrosion

Transition Line

POWER CYCLE PARAMETER FOR WTE PLANT

Considering the characteristics of the Fuel, the power cycle parameter selected for WTE plant will be 45ata

& 400 to 410°C, with a feed water temperature in the order of 130 to

150°C

FOULING / SLAGGING / CORROSION

Ash fouling on the superheater coils

Corrosion in Superheater

Coils

Typical Heat and Mass Balance Diagram for a WTE Plant.

TYPICAL HEAT AND MASS BALANCE DIAGRAM

TURBINE EXHAUST PRESSURE VS POWER OUTPUT

8.60

8.48

8.36 8.26

8.17 8.08

8.00

7.707.807.908.008.108.208.308.408.508.608.70

0.1

ata

0.1

2at

a

0.1

4at

a

0.1

6at

a

0.1

8at

a

0.2

0at

a

0.2

2at

a

WCC ACC

POWER CYCLE PARAMETER EFFICIENCY IMPROVEMENT

Sl.No Description Unit De-aerator LP Heater + De-aerator

LP & HP Heater + De-aerator

1.0 Feed water inlet

temperature

ºC 130 130 150

2.0 Steam Output from Boiler

TPH 43 43 44.3

3.0 Steam to Condenser

TPH 34.3 34.1 33.9

4.0 Power Output kW 8160 8290 8400

The above working is based on a 600TPD WTE plant with fuel GCV of 1724kcal/kg (LCV 1390kcal/kg) . The steam parameters are 45ata & 410°C, with TG exhaust pressure of 0.18ata. The provided values varies based on the

turbine efficiency, ambient conditions and the system configuration

EFFICIENCY IMPROVEMENT – COMMERCIAL GAIN

• Power Output - 8160kW (With DTR)

• Power Output - 8400kW (With DTR + HP & LP Heaters)

• Increase in power generation - 240kW

- 5760units/day

- 19Lakhs units / Year

Savings

• Power cost - 6.0Rs / Unit

• Annual Savings - 114 Lakhs

Additional Investment

• Addition of one HP & LP heater - 50 to 60 Lakhs

Simple Payback - Less Than One Year

IMPROVED HEAT AND MASS BALANCE DIAGRAM

Cycle Heat rate and Plant

Efficiency Calculation

TURBINE EFFICIENCY AND HEAT RATE

Turbine Converts the thermal energy in

steam to mechanical energy.

The Enthalpy drop AB gives the isentropic

expansion and the theoretical work done.

The actual work done is given by AC, which

takes into account the losses.

The turbine cylinder efficiency is (HA-

HC)/(HA-HB).

The losses heat up the steam leaving the

turbine.

Turbine Heat rate is (HA-HC)/kWhr.

PLANT HEAT RATE AND PLANT EFFICIENCY

The heat rate is a term used to define the Power cycle and power

plant efficiencies.

Power Cycle heat rate is defied as the difference in the heat of steam

at boiler outlet in kcal/h and the feed water heat at the inlet of

economizer in kcal/h to the electric energy generated per hour in kWh

Power Cycle Heat rate (CHR) = (Heat of steam at boiler outlet in kcal/h –

Feed water heat at economizer in kcal/h)/(Electrical energy generated per hour in

kWh)

The Power plant heat rate is defined as the quantity of fuel heat in

kcal/hr used for the generation of a unit kWh of electrical energy.

Power Plant Heat rate (PHR) = (Fuel heat input in kg/hr * Gross Calorific Value of

fuel in kcal/kg)/(Electrical energy generated per hour in kWh)

Plant Efficiency = 860 (kcal/kWh)/PHR

SUMMARY

• Water and steam Cycle works under the principle of Rankine cycle

• Higher the steam cycle pressure and temperature and lower the condenser pressure, the cycle efficiency increases. Also higher the feed water temperature at the inlet of the boiler, and more number of heaters, improve the power cycle efficiency.

• However, due the characteristics of the fuel (MSW) and its ash, it is forced to select a power cycle parameter of 45ata & 400 to 410˚C, with a feed water temperature of 130 to 150˚C.

• The condenser pressure is selected based on water availability at site, Ambient conditions, etc. In the case of WCC, the condenser pressure will be 0.12 to 0.1ata. In case of ACC, the condenser pressure will be 0.2 to 0.16ata.

• Based on the Comparison of two HMBD’s (HMBD for a WTE Plant with one De-aeartor and another HMBD with One De-aerator, One HP Heater and One LP heater.) shows that, there is an increase in the power output to an extent of 3.0% while considering HP & LP heaters in the circuit.