1.
Design
Considerations
Design Considerations is the soul of engineering
thinking and consideration. Any lapse on the part of Engineer or entrepreneur
will result in tangible and intangible losses which cannot be made up after the
plant is set up and commissioned. Major design considerations are briefly given
below taking Steel industry as an example but they are equally applicable for
any other industry
1. Must
fulfill the objectives –Desired Production, Quantity/Quality
2. Raw
Materials Balance
3. Water
Balance
4. Energy
Balance
5. Sizing
of Plant Capacities. Balancing the capacities at each stage (for example Beneficiation
Plant works for 300 d/y and pellet Plant works 330 d/y)
6. Modular
Design e.g. 0.2 MTPA, 0.4 MTPA, spacing
of columns, building sizes
7. No
of machines -2 EAF v/s 1 EAF, 2 BF of smaller capacity v/s 1 of bigger
capacity, DRI Plants, Combo Mills instead of 3 different mills etc.
8. Productivity
of machines (e.g. 1.2t/m2.hrto 1.5 t/m2.hr Sinter), 24 MW v/s 30 MW for 0.2
MTPA (4 Link v/s 6 link design of NRCO, 2.4 to 3.2t/m3/day productivity of BF,
18 to 21t/m2. d
9. Inbuilt
capacity for future expansion (Time, cost, shutdown) e.g. Conveyor capacity of
Coal & Coke handling in Coke Oven Plants, Sinter Plants, Power plants, Pellet
Plants, Raw Mats Handling System, Pumps. Piping, Pusher Car/Quenching
Car/Stamping Machines, Cooling Beds, EOT Cranes, Building Design.
10. Rated
Capacity & Design Capacity (20 % More than rated capacity) For aging,
contingencies, increase in productivity (e.g. Sinter Plant, Blast Furnace,
Pellet Plant etc.)
11. Safety
Factors/Dynamic Loading Factors/Slope Factors/Filling Factors/Free Board/Utilization
factor to be taken into account while selecting any machine, vessel or storage
system.
12. Availability
of machines per year. E.g. 330 days per year for Straight Grate and 300 days
per year for Grate kiln technology. 20 h/d versus 24/d (Beneficiation Plant)
13. Life
span of Plant/machines. e.g. Non-Recovery Coke Ovens with silica bricks-based design
life is 20 years, Beehive Oven design life is 3-4 yrs based on Fire clay and 68
years with Alumina Bricks.
14. Materials
Characteristics-Physical, Chemical, Metallurgical, Abrasive, Corrosive,
Fragile, Hydroscopic, Foul smelling,
Gas, Liquid, Lumpy, Powder, Free Flow, Sluggish etc.
15. Specific
Consumptions of utilities, power, water, fuel, refractories, spares, grinding
media per t. (e.g. Grate Kilns have heat consumption of 3.5 Lacs K cal /t v/s
1.8 Lacs K cal /t for Straight Grate), Energy Efficient Ignition furnace
for Sinter Plant heat consumption is 15000 Kcal/t of sinter v/s 30000-45000
Kcal/t of Sinter for other Furnace, For thermal power plants water consumption
is 4 m3/MW for Water Cooled condenser v/s 1.2 m3/MW for air cooled condenser. Similarly,
in Ball Mill or Rod Mill, use of gravity for flow of water can avoid pumping of
water in some cases etc.
16. Checking
for Strength, Stability & Deflection
17. Degree
of automation required.
18. Requirements
of Inserts.
19. Check
for weight of Individual equipment & plant and compare it with similar
plants/equipment.
20. Check
for installed power and compare it with similar plants/equipment
21. Requirements
of man power for operation and maintenance. Check with similar plants and
equipment
22. Requirements
of all utilities, auxiliary facilities, power, water, air, gases, hoisting
& handling, mounted electrics, instruments. Check
with similar plants and equipment
23. Check
for painting requirements considering duty, environment, place, temperature
etc.
24. Provision
of Ramps, Lifts, Platforms, stairs, doors, corridors, restrooms of desired
slopes, widths & dimensions considering normal persons, disability and old
age
25. Nature of the Project: The
proposed project falls under Category-A, under section 3 (A) as per the prevailing EIA Notification,
dated 14th September 2006.
26. Use
of Thumb rules –Check weight of equipment (EOT Crane, Conveyors, Wagons, Transfer
Cars, Raw Mats handling System, Building Structures, Conveyor Galleries,
Junction House-Dead Weight to live load ratios), Check Horse Power, Pump
Capacity
by
using thumb rules to immediately check the adequacy of machines offered by
suppliers.
A
successful holistic design is a solution that is greater than sum of its parts
and takes following into account:
Ø Equitable Use
Ø Flexibility of Use
Ø Simple and Institutive
Ø Size and Shape for easier and comfortable operation
Ø Low Physical Effort
Ø Perceptible Information
Ø Tolerance for Error
2.
Operation
Considerations
After evaluating the plant from design perspective,
the next important parameter is to pay attention to operation considerations. Any
plant or equipment shall be selected for ease and simplicity of operation, with
minimum man power, pollution and maximum safety. Following operating
considerations shall be considered while selecting a plant and equipment or
manufacturing of the same.
1. Ease
of operation – For example Operation of Non-Recovery Coke Oven is quite simple
in nature compared to operation of Recovery Type Coke Oven which is quite
complex and need highly skilled man power. Similarly, operation of a DRI Plant
is much easier than operation of a Blast Furnace.
2. Flexibility
in operation. (Increase decrease capacity, flow rate, t/h rate, product mix,
temperature, pressure, gradient, altitude, humidity, wind)
3. Degree
of automation desired. (Manual, Semi-Automatic or Fully Automatic)
4. Degree
of protection desired (Ambient Temperature, humid, corrosive or hazardous
atmosphere, higher altitude, under pressure etc.)
5. Should
be able to operate smoothly in all prevailing weather conditions considering
Temperature variations, Rain, Wind, Extreme hot, extreme cold etc. (Specially
for Cooling Towers, AC plants, Ventilation, Motors etc.)
6. Take
care of type of duty-Light, Medium, Heavy or Extra Heavy duty conditions
(Motors, Gear Boxes , Cranes, Hoists
etc.) Starting Cycles-No of starts per hour.
7. Quick
changeover of stream from one to another (e.g. Changing the rolling mills
stream in finishing stage )
8. Quick
changeover of parts (e.g. Rolls, Screen, Screen Deck, PCB Cards, Teeth of
Crushers, bearings
9. Comfortable
environment (e.g. Loco Drivers, Crane
Drivers, Pulpit operators, Toll Plaza Collectors)
10. Lower
pollution –Air, Water & Noise ( Lesser fatigue in operation to legs, eyes,
hands, ears, nose.
11. Easy
access to control switches, pedals (Ambassador v/s Maruti, Ford) Nagpur air
port Charging Point location.
12. Operators
manuals
13. Operators
Room
3.
Maintenance
Considerations
This
is another area needing attention while selecting any plant or equipment. The
plant or equipment shall be selected which need minimum maintenance, less
downtime from maintenance perspective. Following are the maintenance
considerations needing attention of engineer/entrepreneur while procuring any
plant or equipment or manufacturing the same.
1. Should
require lesser maintenance
2. Minimum
Down time
3. Fit
& forget concept
4. Easily
approachable-all parts needing maintenance
5.
All casings, shells and frames shall
be split on machine horizontal centerline. Upper halves may be lifted
individually for access to internal parts.
6.
All seals and shaft packings shall
be separate from the main bearing housings and casing structures and may be
readily removed and replaced
7. Proper
hoisting and handling facility (EOT Crane, Manual or Electric
Hoist) with adequate headroom, within the reach of part. Weight of
heaviest part/equipment to be lifted
8. Easy
lowering & lifting into Truck/Trailer
9. Corrosion
& Abrasion
10. Inspection
covers to be provided
11. Man
Holes to be provided
12. Lifting
Lugs to be provided
13. Within
road approach. Design of Junction Houses, Pump Houses, MCC, ECRs, Process
Buildings, Aux Buildings.
14. Choice
of lubrication system-Individual , Group, Manual Centralized/Whether emergency
lubrication system needed.
15. Repair
Bay
16. Repair
station
17. Workshop
18. Maintenance
Manuals
19. Stores
20. Quality
Assurance Plans (QAPs), Inspection Reports, Manuals
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