Energy Management, Consultancy For Energy Savings, Energy Efficiency Audit, Energy Modeling, Mumbai, India
Energy Management, Consultancy For Energy Savings, Energy Efficiency Audit, Energy Modeling, Mumbai, India
Comments: Though the Thermopac capacity and quantity of steam generated are very small, the payback period is very attractive. The same logic can be extrapolated to any size of Waste Heat Recovery system.

STEAM DISTRIBUTION SYSTEM:

The steam distribution system comprises of the following components:

    1. Moisture separator
    2. Pressure reducing station
    3. Piping and its insulation
    4. Steam traps  
All of the above distribution system components contribute largely to efficient plant operations. The effect of individual component on the overall efficiency is very hard to determine.

Following are some of the hard facts regarding steam losses in various components of Steam Distribution system.

Leakage:
Steam Pressure Steam kg/year FO kg/year Rs./Year
Hole Dia of 1/10 Inch
7 kg/cm2)

50,880

 4,070.4 42,780
21 kg/cm2

1,20,000

 9,600 1,00,896
Hole Dia of 1/8 Inch
7 kg/cm2) 2,03,636 16,291 1,71,217
21 kg/cm2 4,80,000 38,400 4,03,584
Hole Dia of 3/16 Inch
7 kg/cm2) 4,58,182 36,655 3,85,244
21 kg/cm2 10,80,000 86,400 6,84,874
Hole Dia of 1/4 Inch
7 kg/cm2) 8,14,545 65,164 9,08,064
21 kg/cm2 19,20,000 1,53,600 16,14,336
Basis : F. O. Price = Rs. 10.5 per kg
- Operating hrs = 8,000 hrs per year
- Steam Ratio = 12.5 kg of steam per kg FO
Loss Due To Improper Insulation :

Steam Temp. Rs./M2/Year
> °C Lagging Thickness
  Bare 1 Inch ½ Inch 2 Inch 2 ½ Inch 3 Inch 4 Inch
38 1590 265 185 - - - -
65 4100 662 529 - - - -
93 7810 1191 794 662 - - -
121 11910 1720 1191 926 - - -
149 17070 2249 1588 1191 1058 - -
177 23150 2778 1984 1588 1191 - -
204 30160 3308 2381 1852 1455 1191 -
232 38390 3969 2778 2117 1720 1455 -
260 47890 4631 3307 2514 1984 1720 -
316 70650 - 4234 3175 2646 2249 1720
371 99220 - - 3969 3307 2778 2117
427 34950 - - 4895 3969 3441 2646
Relation of steam velocities and pressure drop in the pipe :
Pipe Size Steam Pressure kg/cm2

Velocity M/Sec with pressure drop/25 Meters
    0.0175 0.035 0.0525 0.07 0.105 0.14 0.21
3 Inch Pipe 0.338 41 55 72 82 100 120 152
3 Inch Pipe 1.013 26 37 44 52 63 76 96
3 Inch Pipe 1.75 15 23 26 32 40 46 58
3 Inch Pipe 7 9 14 17 20 23 27 35
3 Inch Pipe 28 - - 9 11 12 15 18
6 Inch Pipe 0.338 67 96 122 140 168 191 229
6 Inch Pipe 1.013 4.4 58 73 91 107 123 152
6 Inch Pipe 175 24 35 44 52 61 73 91
6 Inch Pipe 7 15 21 27 32 40 46 55
6 Inch Pipe 28 - 9 14 17 20 23 29
How to read the above table : Example: For 6” pipe, at 7 kg/cm2 pressure the pressure drop in the pipe shall be :
0.0175 kg/cm2 per 25 meters of running length : if velocity is 15 m/s
0.0525 kg/cm2 per 25 meters of running length : if velocity is 27 m/s
0.21 kg/cm2 per 25 meters of running length : if velocity is 55 m/s

Case Study to elaborate the effect of insulation of flanges:  
100 ft of 6 Inch pipe 12 Flanges of 6 Inch = 5 ft of pipe length Heat loss 
in following 3 cases :

Case (I) – Bare pipe ( Bare Flanges) 
Case (II) – Pipe with 2 inch insulation aluminum cladding and bare flanges 
Case (III) – Insulated pipe and Flanges
    Case (I) Case (II) Case (III)

Heat Loss

 Kcal/year 36,300 4,100 2,490

Steam Loss

 Kg/Year/100ft 68 3.2 –

Fuel Loss

 Kg/Year/100ft 55 0.26 –

Energy Saving Potential

 Rs. Per Year/100 ft 60 2.8 –
Present Scenario :-
Boiler Capacity : 850 kg/hr (non-IBR)
Fuel consumption (LDO) : 50 liters per hour (900 liters per day)
Boiler operating hours : 18 per day
Plants to which boiler is attached : Reactor and dryers both indirect heating applications
No moisture separator installed in the line and only TD traps for drain points  After the Moisture separator was installed in the pipeline :
Fuel consumption : 45 liters per hour (630 liters per day)
Boiler operating hours : 14 per day
Energy Conservation Potential :
Daily fuel saving : 270 liters
Annual reduction in fuel bill : Rs. 10 Lacs
Investment Required : Rs. 4,500/-

Additionally the production capacity increased due to availability 
of the production equipment for longer durations.

STEAM UTILIZATION SYSTEM : This area is most potent for energy conservation.  The application, end use utility and quality of steam are the three main points that govern energy performance of the system. Energy performance of the system can be drastically improved by close examination of the system. The energy saving is affected by following measures:

Reducing the demand of steam by modification of application system by:

  • Reduction in operating hours

  • Reduction in quantity required per hour

  • Use of more efficient technology

  • Minimizing wastage

We shall elaborate the efficiency enhancement process by suitable 
examples of each type.


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