Best Practices for Utility Operation - Knowledge …...2016/02/08 · e m p e r a t u r e s ( C) 0 Enthalpy (M W)-5 0 0 -4 5 0 -4 0 0 -3 5 0 -3 0 0 -25 0 -20 0 -15 0 -10 0 -5 0 0

WE SERVE TO MOTIVATE AND CATALYSE TECHNOLOGICAL EXCELLENECE

Sustainability

Values we value: Integrity Commitment Passion Seamlessness Speed

Best Practices for Utility Operation &

Efficient System Design

Corporate Technical & Energy Services


Sustainability


Overview - Best Practices

• Maintain steam header pressure as low as possible

• Evaluate refrigeration configuration using Pinch Technique

• Real Time optimizer for Steam/Power balance

• Enhance insulation effectiveness

• Supply Cooling water at high temp/low flow rate to cooling tower

• Explore various options for low grade heat recovery


Sustainability


Steam Header Pressure Reduction

3


Sustainability


Sensitivity of Header Pressure on Power generation

100 TP H @360 ° C

42.5 bar g

3.5 bar g

∆P =39 bar

n =75%

P ower Gen: 10.182 M W

100 TP H @360 ° C

42 bar g

3 bar g

∆P =39 bar

n =75%


Increase of ~430 KW

Increase of ~390 KW

100 TP H @360 ° C

42.5 bar g

3 bar g

∆P =39.5 bar

n =75%



Sustainability


Mollier Chart for Steam

High Slope. Change in enthalpy

low

Slope is low. Change in enthalpy is high

Slope = ΔP/ΔH


Sustainability


Total Site Pinch Analysis

100

200

300

400

500

Tem

pera

ture

s (°

C)

0

Enthalpy (MW)

0 50 100 150 200 250 300 350 400 450 500-50-100-150-200-250-300-350-400-450-500

Cooling water

Hot water

LP SteamLP Steam

HP Steam

SHP Steam

Ref: Heat Exchanger Network Synthesis by Dr Uday V. Shenoy Chemical Process Design and Integration by Robin smith


Sustainability


Efficient Refrigeration System Design

7


Sustainability


Efficient Refrigeration System Design

•What is the benchmark specific

power consumption for Ammonia

refrigeration system ?

•Or Do we have a tool to determine

?.....

Probable Answer - Try Pinch Technique

Co

mp

ress

ion

Rat

io/

Wo

rk

CW Temp = 32 ˚C

Evaporator Temp = -2 ˚C

Area α Ideal Work

T

H

23 ˚C

2 ˚C

Refrigeration Load

CW Temp = 32 ˚C


Area = Ideal Work

Car

no

t Fa

cto

r (η

)

H

23 ˚C

2 ˚C

Wideal = Qrefrign / COPideal Wactual = Qrefrign / (COPideal * ηsystem) ηsystem= 0.5

η = T0 / (T0 – T) Wactual = Wideal / ηsystem ηsystem= 0.5


Sustainability


Illustration- Single Stage System C

om

pre

ssio

n R

atio

/ W

ork

CW Temp = 32 ˚C


Area α Ideal Work

T

H

23 ˚C

2 ˚C

Refrigeration Load

Wideal = Qrefrign / COPideal Wactual = Qrefrign / (COPideal * ηsystem) ηsystem= 0.5

COP ideal = 305 (305-271) = 9 Work = 3516 kW ----- (1000 TR) (9*0.5) = 780 KW SPC = 0.78 KW/TR


Sustainability


Illustration - Two Stage System

• Two Stage System:

Energy Reduction.

Co

mp

ress

ion

Rat

io/

Wo

rk

CW Temp = 32 ˚C


Area α Ideal Work

T

H

23 ˚C

2 ˚C

Evaporator Temp = 6 ˚C

Parameters Stage 1 Stage 2

Duty in KW 2000 1516

CT Temp in K 305 305

Ref Level in K 280 271

COP ideal 12 9

Power in KW 333 337

Total Power in KW 670

SPC in kW / TR 0.67

Power Reduction of 14%


Sustainability


Real Time Optimizer for Steam/Power

11


Sustainability


Steam & Power Network


Sustainability


Key Benefits of Real Time Optimizer

• Reduce operating cost by 3 to 5 % from current level

• Maximize use of cheaper fuel in fluctuating market

• Handy Planning tool for partial shutdowns.

• Evaluate global impact of Energy Reduction schemes.

• Informed decision making tool for operating crew


Sustainability


Typical Recommendations

• Fuel switch over ( NG/FO) as configured

• Steam generation by maximizing in HRSG/minimizing in boiler

• Turbine /motor drives change over

• To load efficient machine

• To maintain Low Deaerator pressure to avoid dumping steam


Sustainability


Effective Insulation

15


Sustainability


Effective Insulation

390 ˚C

Mineral Wool – 200

mm

Heat Loss = 190 W/ m

390 ˚C

Pyrogel – 65 mm


Pyrogel – 10 mm

390 ˚C


Mineral Wool – 100 mm

Pyrogel – 20 mm

Significant factors affecting insulation effectiveness

• Moisture Absorption capacity

• Burnout at temp > 350 deg C

6 to 8 times costlier than Mineral Wool

Optimum solution


Sustainability


Effect of Wind on Insulation Surface Temp

Wind Velocity (m/s)

Insulation Thickness (mm)

Surface Temperature (˚C)

Heat Loss (W/m)

0.0 200 49.3 190.1

1.0 200 44.9 191.4

2.0 200 40.5 192.6

3.0 200 38.2 193.3

4.0 200 36.8 193.7

5.0 200 35.9 194.0

7.0 200 34.6 194.3

10.0 200 33.5 194.6

Conduction = Radiation + Convective loss

Note: 3E Plus software used for calculation


Sustainability


Supply Cooling Water at High Temp/Low Flow

Rate to Cooling Tower

18


Sustainability


Design Condition – A case study

Parameters Unit Value

CW Circulation Rate m3/hr 9500 Hot Water Temperature ˚C 46.2 Cold Water Temperature ˚C 35 Wet Bulb Temperature ˚C 29 Dry Bulb Temperature ˚C 30 Fan Driver Power kW 220 Barometric Pressure kPa 101.145 Liquid to Gas Ratio - 1.732

1.732

• Countercurrent Induced Draft • Film Type Fills

Option 1

Option 2

Case – Increase in heat load by 10% in existing cooling tower


Sustainability


Effective use of Cooling Tower

Note: CTI software used for calculation/performance evaluation


Sustainability


Low Grade Heat Recovery Options

21


Sustainability


Basis for evaluation of Heat recovery options

Basis

•Waste stream temperature reduction : 120 to 100 oC

•Quantum of waste heat : 1.0 Gcal/hr

•Boiler efficiency : 80%

•GCV of coal : 4000 kcal/kg

•Cost of coal : Rs 4/kg

•COP of VAM : 0.6

•COP of heat pump : 0.4

•ORC system efficiency : 10%

•Annual operating hours : 8000

•Steam turbine isentropic efficiency : 75%


Sustainability


Sr No. Options for heat recovery Actual Input energy reduction in Boiler

Annual Saving in Rs Lakhs

1 Process Preheating ( DM water/Air) 55% 44

2 Organic Rankine Cycle for Power generation

41% 33

3 VAM for chilled water generation 34% 27

4 Steam generation and Mechanical vapour compressor

27% 22

5 Heat pump to generate LP steam 24% 20

Summary


Sustainability


Thank You

Documents

Best Practices for Utility Operation - Knowledge …...2016/02/08 · e m p e r a t u r e s ( C) 0 Enthalpy (M W)-5 0 0 -4 5 0 -4 0 0 -3 5 0 -3 0 0 -25 0 -20 0 -15 0 -10 0 -5 0 0