Natural Cooling Tower – Pyramid Shaped Structure using Simple design

By | 16/01/2012

Ordinary Cooling Tower Design is tedious one and also it includes design of rafter columns. This rafter columns are inclined both in X and Y axis so designing involves difficult calculations. So new researches are going to simplify the design and in mean while not to decrease its efficiency..

Here, I have included my project which involves planning, analysing and designing of Pyramid shaped natural cooling tower.. Also try rectangular shaped structure if anybody interested..

NATURAL COOLING TOWER-PYRAMID SHAPED STRUCTURE

ABSTRACT

Our project involves the Planning, Analysis and Design of an Natural Cooling Tower. The entire design includes slab design, beam design, column design, and footing design. Calculations are made manually and using software packages.

The various structural elements are designed using IS 456:2000. The concrete mix used for slabs, beams and footings are of M25 and the steel used for all members are high yield strength deformed bars of grade Fe415. Each and every part is designed by considering the safety point of view and economically.

This project deals with a simple and effective Natural Cooling Tower design which is designed similar to Pyramid structure with slight modification to increase its efficiency instead of normal Sand-Clock like structure which involves tough calculations and tedious rafter column designs.

This is a new concept in Cooling Tower design which strike in our mind when we were gone to Industrial Visit at Mettur Themal Power Station.

The total area of Cooling tower is 662 m2 with three compartments which are used for cooling the hot water supplied to it. The first bottom compartment consists of filler material above which steel grill is placed to hold the distribution pipe with sprinklers which carries the hot water and sprinkles it. The Second compartment which is above the first compartment will have a big slab with opening at the centre which converges and reduces the area of vapour reaching the top. Obviously, the vapour starts to condense more and reaches the collecting chamber at the bottom. And the third, topmost compartment consists of empty space which has a large opening at the centre than at the Second compartment which allows the remaining vapour that comes out after condensing at second compartment to reach the top widely.

The objectives of this project are

Main objective:

  • To create a new design in cooling tower construction instead of conventional structures which are tedious to built
    • To prepare an economical and effective design using Pyramid like structure
    • To make use of atmospheric air for natural cooling instead of electric fan
    • To prepare simple design instead of complicated design (to avoid designing of Rafter Column as like in normal cooling tower)

Supplementary Objective:

  • To draw a plan of Natural Cooling Tower showing the reinforcement details of slabs, columns, beams and footings are done AutoCAD 2009.
  • To analyze the structure elements using STADD. Pro V8i and to verify the results with manual design results.

 

CHAPTER 1

INTRODUCTION

1.1 GENERAL

In this present era, the technology in advanced construction has developed to a very large extent. Some parts of constructions are still in improving stage which includes Cooling Tower construction. Some researches are going on to increase the efficiency of Cooling Tower by modifying its structure and design. Ordinary Sand-Clock shaped Cooling Towers are very tedious to design and calculate. In this chapter, we are going to deal with planning, analysis and design of Natural Cooling Tower in brief.

1.2 ABOUT AUTO CADD SOFTWARE

AutoCAD is the most popular 2D CAD software from Autodesk, a leading US based company. AutoCAD 2012 is the latest version of AutoCAD series. AutoCAD 2012 features focus on getting you through your everyday tasks quicker and with fewer errors. Simply put, create, collaborate, and deliver more efficiently than ever.

1.3 ABOUT STAAD Pro V8i

STAAD Pro V8i is one of the most popular latest structural engineering software product for model generation, analysis. It has an intuitive, user-friendly visualization tools, powerful analysis and design facilities and seamless integration to several other modelling and design software products. The software is fully compatible with all windows operating system but is optimized for windows XP.

1.4 COOLING TOWER

Cooling Towers are evaporative coolers used for cooling water or other working medium to near the ambient wet-bulb air temperature. Cooling towers use evaporation of water to reject heat from processes such as cooling the circulating water used in oil refineries and power plants, building cooling, or chemical reactions.

 

1.4 TYPES OF COOLING TOWERS

1.4.1 MECHANICAL DRAFT COOLING TOWERS

Mechanical Draft Cooling tower has following characteristics,

  • Large fans to force air through circulated water
  • Water falls over fill surfaces: maximum heat transfer
  • Cooling rates depend on many parameters
  • Large range of capacities
  • Can be grouped, e.g. 8-cell tower

DISADVANTAGES OF MECHANCIAL DRAFT COOLING TOWER

  • High vibration values during startup.
  • Complex gearbox (1800/120 RPM)
  • Starting cell 2 can shut down cell 1
  • Reversing fans in cold climates
  • Water build up in blades
  • Speeds are slow and based on diameter
  • Corrosion from bad pH

1.4.2 NATURAL DRAFT COOLING TOWER

A natural draft cooling tower is a means to remove waste heat from a system and release it into the atmosphere. Typically used at oil refineries, chemical plants and power plants to remove heat absorbed from circulating cool water systems. A common shape is the hyperboloid (See Fig. 1) Cooling towers have been around for over 100 years. However, in their early for were only about 20 meters high. Today, some can reach over 200 meters.“As recently as 20 years ago, cooling towers were more the exception than the rule in the industry because of their severely high operating cost and the large amount of capital required for construction. But with today’s need for water conservation and minimal environmental impact. industry is turning more and more to recycling water.”(GC3) . It has following advantages,

  • Hot air moves through tower
  • Fresh cool air is drawn into the tower from bottom
  • No fan required
  • Concrete tower <200 m
  • Used for large heat duties

COMPONENTS

  • Supply Basin
  • Tower Pumps
  • Cooling Towers

– Vertical Ribs

– Reinforced Concrete Shell

– Internal Void

– Diagonal Columns

  • Fill
  • Hot Water Distribution System
  • Cold Water Collection
  • Drift Eliminators – Drift is water lost from cooling towers as liquid droplets are entrained in the exhaust air. The drift loss is independent of the water lost by evaporation. The drift loss may be expressed in units of lb/hr or percentage of circulating water flow. Drift eliminators are used to control this drift loss from the tower.

There are two types of Natural Draft Cooling Towers. They are,

(i) Cross Flow Type – Mechanical Draft Cooling Tower

(ii) Counter Flow Type – Mechanical Draft Cooling Tower

But our new design of Cooling Tower is designed rectifying the demerits in the above designs. It has a structure with opening at bottom has three compartments which are used for cooling the hot water supplied to it. The first bottom compartment consists of filler material above which steel grill is placed to hold the distribution pipe with sprinklers which carries the hot water and sprinkles it. The Second compartment which is above the first compartment will have a big slab with opening (3.3mx3.3m) at the centre which converges and reduces the area of vapour reaching the top. Obviously, the vapour starts to condense more and reaches the collecting chamber at the bottom. And the third, topmost compartment consists of empty space which has a large opening at the centre (10.2mx10.2m) than at the Second compartment which allows the remaining vapour that comes out after condensing at second compartment to reach the top widely.

this is the over all process…

This is how filler works…

CHAPTER 2

RESULTS AND DISCUSSION

PREPARATION OF PLAN

Fig 3.1 Natural Cooling Tower Plan


 

Staad Pro View

STADD.PRO RESULT

SLAB DESIGN

 

ELEMENT LONG. REINF MOM-X /LOAD TRANS. REINF MOM-Y /LOAD

(SQ.MM/ME) (kN-M/M) (SQ.MM/ME) (kN-M/M)

 

60 TOP : 696. 14.08 / 3 696. 4.98 / 3

BOTT: 696. -1.26 / 2 696. -0.24 / 2

 

61 TOP : 696. 3.02 / 3 696. 15.85 / 3

BOTT: 696. -0.08 / 2 696. -1.48 / 2

 

62 TOP : 696. 3.20 / 3 696. 17.02 / 3

BOTT: 696. -0.10 / 2 696. -1.60 / 2

 

63 TOP : 696. 3.04 / 3 696. 15.53 / 3

BOTT: 696. -0.08 / 2 696. -1.47 / 2

BEAM DESIGN

FOR BOTTOM BEAM

B E A M N O. 1 D E S I G N R E S U L T S

M25 Fe415 (Main) Fe415 (Sec.)

LENGTH: 10500.0 mm SIZE: 550.0 mm X 550.0 mm COVER: 25.0 mm

SUMMARY OF REINF. AREA (Sq.mm)

—————————————————————————-

SECTION 0.0 mm 2625.0 mm 5250.0 mm 7875.0 mm 10500.0 mm

—————————————————————————-

TOP 619.58 585.78 585.78 585.78 723.91

REINF. (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm)

 

BOTTOM 0.00 582.40 582.40 582.40 0.00

REINF. (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm)

—————————————————————————-

SUMMARY OF PROVIDED REINF. AREA

—————————————————————————-

SECTION 0.0 mm 2625.0 mm 5250.0 mm 7875.0 mm 10500.0 mm

—————————————————————————-

TOP 8-10í 8-10í 8-10í 8-10í 10-10í

REINF. 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s)

 

BOTTOM 2-16í 4-16í 4-16í 4-16í 2-16í

REINF. 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s)

 

SHEAR 2 legged 8í 2 legged 8í 2 legged 8í 2 legged 8í 2 legged 8í

REINF. @ 160 mm c/c @ 160 mm c/c @ 160 mm c/c @ 160 mm c/c @ 160 mm c/c

—————————————————————————-

SHEAR DESIGN RESULTS AT DISTANCE d (EFFECTIVE DEPTH) FROM FACE OF THE SUPPORT

 

SHEAR DESIGN RESULTS AT 815.0 mm AWAY FROM START SUPPORT

VY = 40.97 MX = 2.91 LD= 3

Provide 2 Legged 8í @ 160 mm c/c

 

SHEAR DESIGN RESULTS AT 815.0 mm AWAY FROM END SUPPORT

VY = -53.86 MX = 2.91 LD= 3

Provide 2 Legged 8í @ 160 mm c/c

Similar results for 8 bottom beams.

FOR INCLINED BEAM

B E A M N O. 53 D E S I G N R E S U L T S

M25 Fe415 (Main) Fe415 (Sec.)

LENGTH: 14637.6 mm SIZE: 550.0 mm X 550.0 mm COVER: 25.0 mm

SUMMARY OF REINF. AREA (Sq.mm)

—————————————————————————

SECTION 0.0 mm 3659.4 mm 7318.8 mm 10978.2 mm 14637.6 mm

—————————————————————————-

TOP 582.40 582.40 582.40 582.40 582.40

REINF. (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm)

 

BOTTOM 0.00 582.40 582.40 582.40 0.00

REINF. (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm)

—————————————————————————-

SUMMARY OF PROVIDED REINF. AREA

—————————————————————————-

SECTION 0.0 mm 3659.4 mm 7318.8 mm 10978.2 mm 14637.6 mm

—————————————————————————-

TOP 4-16í 4-16í 4-16í 4-16í 4-16í

REINF. 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s)

 

BOTTOM 2-16í 4-16í 4-16í 4-16í 2-16í

REINF. 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s)

SHEAR 2 legged 8í 2 legged 8í 2 legged 8í 2 legged 8í 2 legged 8í

REINF. @ 160 mm c/c @ 160 mm c/c @ 160 mm c/c @ 160 mm c/c @ 160 mm c/c

Similar results for 4 Inclined beams.

FOR TOP BEAM

B E A M N O. 56 D E S I G N R E S U L T S

M25 Fe415 (Main) Fe415 (Sec.)

LENGTH: 10000.0 mm SIZE: 400.0 mm X 400.0 mm COVER: 25.0 mm

STAAD SPACE — PAGE NO. 17

SUMMARY OF REINF. AREA (Sq.mm)

—————————————————————————-

SECTION 0.0 mm 2500.0 mm 5000.0 mm 7500.0 mm 10000.0 mm

—————————————————————————-

TOP 395.68 0.00 0.00 0.00 391.28

REINF. (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm)

 

BOTTOM 303.13 303.13 303.13 303.13 303.13

REINF. (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm)

—————————————————————————-

SUMMARY OF PROVIDED REINF. AREA

—————————————————————————-

SECTION 0.0 mm 2500.0 mm 5000.0 mm 7500.0 mm 10000.0 mm

—————————————————————————-

TOP 3-16í 2-16í 2-16í 2-16í 3-16í

REINF. 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s)

 

BOTTOM 4-10í 4-10í 4-10í 4-10í 4-10í

REINF. 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s)

 

SHEAR 2 legged 8í 2 legged 8í 2 legged 8í 2 legged 8í 2 legged 8í

REINF. @ 170 mm c/c @ 170 mm c/c @ 170 mm c/c @ 170 mm c/c @ 170 mm c/c

Similar results for 4 top beams.

COLUMN DESIGN

C O L U M N N O. 13 D E S I G N R E S U L T S

M25 Fe415 (Main) Fe415 (Sec.)

LENGTH: 3000.0 mm CROSS SECTION: 600.0 mm X 600.0 mm COVER: 40.0 mm

** GUIDING LOAD CASE: 3 END JOINT: 1 SHORT COLUMN

REQD. STEEL AREA : 7395.32 Sq.mm.

REQD. CONCRETE AREA: 352604.69 Sq.mm.

MAIN REINFORCEMENT : Provide 24 – 20 dia. (2.09%, 7539.82 Sq.mm.)

(Equally distributed)

TIE REINFORCEMENT : Provide 8 mm dia. rectangular ties @ 300 mm c/c

 

SECTION CAPACITY BASED ON REINFORCEMENT REQUIRED (kNS-MET)

———————————————————-

Puz : 6268.60 Muz1 : 265.71 Muy1 : 265.71

 

INTERACTION RATIO: 0.99 (as per Cl. 39.6, IS456:2000)

 

SECTION CAPACITY BASED ON REINFORCEMENT PROVIDED (kNS-MET)

———————————————————-

WORST LOAD CASE: 3

END JOINT: 10 Puz : 5621.05 Muz : 0.00 Muy : 0.00 IR: 0.95

Similar results for 8 columns.

REINFORCEMENT DETAILS

Fig 3.2 Bottom Beam Reinforcement Details

 

Fig 3.3 Inclined Beam Reinforcement Details

 

 

Fig 3.4 Top Beam Reinforcement Details

Fig 3.5 Column Reinforcement Details


Footing 2

Fig 3. 6 Footing Reinforcement Details

Staad Pro Views

 

Friends… Modify whatever you want if you feel wrong and design a new structures like this…. all the best guys…

If you need AutoCAD plan and StaadPro files for reference…. mail to ramanan.moon@gmail.com

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