c.tower.docx

8/11/2019 c.tower.docx

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Subject: ORB-II COOLING TOWER SYSTEM

BYCO purchased three pumps and 5 fans of a cooling water system from Milford Haven UK

along with Refinery. There were four pumps at Milford Haven, two motor driven while two

turbines driven. One Large capacity motor driven pump was missing during the time of

purchase. Bosicor purchased new cells along with partial piping, side stream filters + pump.

At first stage BYCO will run with three cells commissioned along with three pumps (one

motor and two turbines driven). Specs of pumps and fans are given below:

Milford Haven Refinery cooling water system was designed to reject 160.8MMBtu/h heat

with its temperature change of 30oF (110- 80oF). So, the water circulation rate was around

11000 gpm. Design conditions were as follows:

Sr.No Parameter Summer

1. Supply temperature, oF 80

2. Return temperature, oF 110

3. Ambient temperature (avg), oF 85

4. Wet Bulb temperature, (avg), oF 75

5. Relative Humidity, % 65 -

At Milford Haven, there were two cooling towers. One cooling tower had two cells while the

other had three cells. Two cells cooling tower had 16ft dia, 6 blades of GRP fans with 60hP

motors while three cells cooling tower had 16ft dia, 4 blades of FRP fans with 50hP drivers.

Two cells tower was feeding to VDU and Isomerization unit & Plat splitter unit while other

process units were with 3 cells tower.

1. Cooling Water pumps, Flow (5160gpm), head (175.4ft) and power 320 hp Motor/Turbine

(1/1)

2. Cooling Water pumps, Flow (6000gpm), head (161.7ft) and power 400 hp Motor/Turbine

(1/1). Pump with motor is missing.

3. Fans, 16 ft dia, 6 blade FRP 60 hP Motor 3

4. Fans, 16 ft dia, 4 blades FRP 50 hP Motor 2


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Ambient conditions in Pakistan are hotter than that at Milford Haven and they are as

follows:

Sr.No Parameter Summer

1. Supply temperature, oF 90

2. Return temperature, oF 120

3. Ambient temperature (avg), oF 95

4. Wet Bulb temperature, (avg), oF 85

5. Relative Humidity, % 65

So hot weather would require higher water circulation rate and/or increase in heat transfer

area. To have more water circulation rate, provision has been taken to add 3 more cells.

Only one additional pump will handle the future additional requirement of the water.

However, current piping network, along with available differential head of pumps, will not

be able to handle the additional water circulation rate and piping network debottlenecking

would be required.

For initial Refinery operation, 5 cells (induced draft counter flow) of each capacity 540

m3/hr have been selected in order to achieve heat rejection of 160 MM BTU/HR.

BYCO is installing 4 cells in first phase with refurbished rotating equipment (Fan motors,

gear drives, shafts, fan blades & complete fan assembly), provided by BYCO while rest of

cooling tower parts are in scope of supplier.

Side Stream Filtration

Side stream Filtration system has been designed to keep the turbidity level below 1 NTU by

removing suspended solids. The design flow rate of the system is 600 gpm. Filtration

system has two filters and one pump. It has been provided with line from main cooling

water supply pumps.

Filters are sand filled units which will operate at certain pressure drop. At specified

pressure drop one of the filters will be taken off the line and will go on regeneration /

backwashing while the other will be on line.

Details & operational sequence of Side stream filter package is given in attached doc# SP-J-

001.

Chemical Dosing System:-


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Chemical dosing system requirements are given in attached doc# 1197-22-CH-1502.

COOLING TOWER DESIGN PARAMETERS

Circulation rate m3/hr 2160

No. of cells No. 4

Summer Case

Supply temperature 0C 32

Return temperature 0C 47

Range 0C 15

Wet bulb temperature(Avg) 0C 29

Approach 0C 3

Relative Humidity % 65

COOLING TOWER BASIN DIMENSIONS

Length m 12.825

Width m 8.7

Depth 2.35

Volume m3 262.2

No. of basin 2

Total Volume m3 524

SYSTEM VOLUME

ONE HEADER

Pipe dia inch 20

Length m 1000

2nd HEADER

Pipe dia inch 16

Length m 1000

2NDheader will2nd header will be in operation in future when

cooling tower capacity would be 2700 m3/hr

LABORATORY RESULTS MAKE UP WATER COOLING WATER

Target Target

pH 7.00 8 - 9


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TDS ppm (as CaCO3) 300 - 350 < 1500

NaCl ppm (as CaCO3) 50 - 70 < 500

T.HARD ppm (as CaCO3) 89 - 150 < 800

Ca HARD ppm (as CaCO3) 70 - 110 < 500

M. ALK ppm (as CaCO3) 90 - 150 < 700

ZINC - 1 - 2

TO bemaintain

FREE HALOGEN (B) -

CONC. FACTOR (NaCl) - 5.0 - 6.0

CONC. FACTOR (TDS) - 5.0 - 6.0

RYZNAR INDEX:


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As soon as all parameters are normalized, normal dosages of the chemicals

shall be followed, and a corrosion coupon shall be installed in corrosion

coupon assembly, corrosion coupon is lying with our rep. at site.

We are already conducting biological counts test at site, you may ask your

engineer to coordinate with our rep. for timing schedule.

Cooling Tower is operated at high CF and TDS level, therefore, Turbidity hasno significant role in cooling water chemistry, however monitoring of

suspended solids in cooling water circuit can help to address and resolve

the sludge accumulation issue.

c.tower.docx

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