BRAHMAPUTRA CRACKER & POLYMER LIMITED Quality …...temperature drop of oxidized caustic/vapor...

BRAHMAPUTRA CRACKER & POLYMER LIMITED

Quality Circle Project

(Ranabir Tarat) (Pranjal Kakoty) (R. P. Singh)

Team Leader Champion HOD

Project Title: Performance restoration of WAO Process Cooler of Ethylene Cracker Unit of BCPL, Lepetkata.

(Project registration no. : BCPL/LEP/MECH/ECU/QC/03 dated 15/02/2019)

Quality Circle Project by

Team Leader : Mr. Ranabir Tarat Team Members :

Md. Kalamuddin

Mr. Nabajit Das

Mr. Nitul Kalita

Mr. Pankaj Kumar

Mrs. Niharika Kakati

Mr. Angshuman Gogoi

Mr. Chandan Dowari

Mr. Polakh Protim Boruah

Champion : Mr. Pranjal Kakoty

HOD : Mr. R.P.Singh


QUALITY CIRCLE PROJECT REGISTRATION

WORK CENTER: BCPL As on: 15/02/2019

(Pranjal Kakoty) (R. P. Singh) (R. P. Singh)


1. Project Registration No.

(To be given by QC Coordinator*)

BCPL/LEP/MECH/ECU/QC/03

2. QC Team Name Explorer

3. a. Team Leader Mr. Ranabir Tarat

b. Team Members Md. Kalamuddin

Mr. Nabajit Das

Mr. Nitul Kalita

Mr. Pankaj Kumar


Mr. Angshuman Gogoi

Mr. Chandan Dowari


4. Champion Mr Pranjal Kakoty

5. HOD Mr R.P.Singh

6. Project Title

(Should be Specific, Measurable, Achievable,

Realistic, Time Bound)

Performance restoration of WAO Process Cooler of

Ethylene Cracker Unit (ECU) of BCPL, Lepetkata.

7. Potential Benefits:

Tangible

1. By performance restoration of WAO process cooler,

erosion of waste water piping and machineries can be

minimized.

2. Cost benefit by reducing maintenance cost.

8. Target Completion Date

(Plan the activities in milestone chart below)

15/02/2019.

Milestone Chart

No. Activity week

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

Targ

et

1. Defining the

problem

2. Analyzing the

problem

3. Identifying the causes

4. Finding out the root

causes

5. Data Analysis

6. Developing solution

7. Foreseeing possible

resistance

8. Trial implementation and

checking

performance

9. Regular implementation

10. Follow up/Review

BRAHMAPUTRA CRACKER & POLYMER LIMITED QUALITY CIRCLE PROJECT - STATUS REPORT




1. Project Registration No.:

(To be given by QC Coordinator*)

BCPL/LEPK/MECH/ECU/QC/2018-19/03

2. QC Team Name: Explorer

3. a. Team Leader: Mr. Ranabir Tarat

b. Team Members: Md. Kalamuddin

Mr. Nabajit Das

Mr. Nitul Kalita

Mr. Pankaj Kumar


Mr. Angshuman Gogoi

Mr. Chandan Dowari


4. Champion/HOD: Mr. Pranjal Kakoty / Mr. R. P. Singh

5.

Improvement Project:

Project Title:

Performance restoration of WAO Process Cooler of

Ethylene Cracker Unit (ECU) of BCPL, Lepetkata.

Introduction:

The purpose of the Wet Air Oxidation System is to reduce

the concentration of sulfides (to less than 1 mg/l)

contained in the spent caustic. It converts sodium sulfide

in the pretreated spent caustic to sodium sulfate. The

effluent from the Wet Air Oxidation (WAO) System is

then neutralized by sulfuric acid and routed to waste water

treatment plant for blending with other effluent streams.

WAO feed pump (116-PA-801A/B) receives spent caustic

from the spent caustic storage tank and raises its pressure.

The high pressure air from one of the WAO Air

Compressor (116-KA-801A/B) is combined with the

above liquid feed just before entering to WAO

feed/effluent heat exchanger (116-EE-801). Then the

mixture enters the WAO Reactor (116-RB-801) where the

chemical oxidation reactions occur that will cause an

increase in temperature. Operating pressure in the reactor

is approximately 28 kg/cm2g. The temperature of the

reactor is controlled by adding de-superheated steam. The

steam flow is then sent through a sparger pipe into the





WAO Reactor. The hot oxidized reactor discharge

products are directed to the shell side of 116-EE-801

where heat is transferred to the cold feed of reactor

entering the exchanger.

Upon exiting the shell side of 116-EE-801, the oxidized

spent caustic and vapor is passed through the tubes of the

WAO Process Cooler (116-EE-802). Cooling water is

used on the shell side to cool the reactor discharge

products to approximately 50°C.

The oxidized caustic/vapor mixture leaving 116-EE-802 is

de-pressurized to approximately 7 kg/cm2g through one

of two pneumatically operated pressure control valves

which discharge into the WAO Separator (116-VV-801),

where liquid/vapor phases of the reactor discharge

products separate into their respective phases. The

oxidized spent caustic is available at 6 kg/cm2g at the

battery limit.

Technical Problem:

1. The outlet temperature of oxidized caustic/vapor

mixture from WAO process cooler (116-EE-802) is

expected to be 50OC. But due to leaking of tube side

oxidized caustic/vapor mixture between the different

passes of the exchanger, the cooling effect has not

been achieved.

2. Outlet process fluid temperature was dropped by 10OC

through external water cooling.

Remedial Actions taken:

A brain storming session was done among all the team

members in order to analyse the problem and arrive at the

solution. It was decided to thoroughly inspect the

complete system as per the installation and O&M manual.

As discussed above, WAO Process Cooler was unable to

cool the oxidized spent caustic and vapor. Thus the

exchanger was opened in both fixed and floating head

side. It was observed that inlet fluid stream from tube side

goes to outlet nozzle without travelling the entire tube

length which is due to leakage through the joint at the





partition and fixed tube sheet of the exchanger. It is

decided to attend the problem as per below action plan:

1. Change of channel head side tube sheet gaskets.

2. Gasket changed but no improvement observed.

3. Inspection of partition portion at channel and

floating head side.

4. On floating head side groove found ok. On

channel head side no groove was observed in the

partition plate. Also, the welded tube end has

resulted in loss of evenness of the tube sheet face.

This unevenness was corrected.

Brief Details of the jobs done:

Since there was no

temperature drop of

oxidized caustic/vapor

mixture at tube side outlet

of WAO process cooler

hence initially the outlet

line had to be cooled

through external cooling

by water spraying.

For finding solution of the problem, thorough inspection

the system was done by the team.

Considering that no heat transfer was observed in the heat

exchanger, there is confirm possibility of inter pass

mixing of the tube side fluid without travelling its entire

length. Based on the observation, the following actions are

being taken.

OPTION-1: Tube sheet side and end flange side gasket of

the channel head and floating head gasket are changed.





Leakage checked through water and it was found that

while water was allowed to enter to pass through drain

point, it instantly passes through the balance drains.

OPTION-2: Belzona adhesive was used while fixing the

gasket, and during leak checking as per above procedure,

no leakage was observed. Thus, the exchanger was

allowed to be in line, but temperature was not dropped

below 70OC.

OPTION-3: Belzona adhesive was used and metal braded

sheet gaskets were used in both sides of the channel head.

During leak checking as per procedure at Option-1 above,

no leakage was observed. Thus, the exchanger was

allowed to line. This time temperature dropped below

50oC was achieved but it sustained for approx. 3 days.

From the outcome of Option-2 and 3 above following is

concluded.

1. In the SS jacketed gasket in partition with spiral

wound at outer periphery, the partition planes at

channel head could not compress the jacketed portion

at the tube sheet. Thus the tube side fluid leaks.

2. During use of metal braded sheet gasket, this indicates





that the either tube sheet surface or partition planes are

not straight. But the sheet gasket accommodates the

unevenness and the leak arrests. But again the sheet

gasket melts due to high temperature above 180OC of

the inlet tube side fluid.

Thus we need to make the uneven face even both at fixed

tube sheet end and channel head end. Also, creation of

groove at the fixed tube sheet shall assist in effective

fitment of the partition plane. Two ways are selected to

create the groove and create evenness, either by coating

material buildup at the tube sheet or by machining.

OPTION-4: The coating material buildup procedure as it

is cheaper is adopted. Grooves were created and the tube

sheet surface was made even. Then the exchanged is

boxed up with SS jacketed with outer spiral wound gasket

and then taken inline. This time temperature dropped was

achieved for hardly one day. The exchanger was reopen to

see the effect and it is observed that the protective coating

and buildup material is completed washed away.

This means that the protective coating and buildup

material cannot resist the effect of oxidized caustic/vapor

mixture.

OPTION-5: The heat exchanger was vertical in nature





with floating head side is at the top side. Also the heat

exchanger was installed within a structural enclosure.

Thus, the tube bundle cannot be removed for modification

purpose. Hence, in-situ machining method is adopted.

Grooves were created through in-situ milling operation.

The tube sheet surface and the partition planes at the

channel head were made even by in-situ machining. An

offset of 0.5mm was kept between the grove and the outer

machined surface at the tube sheet to cater the difference

in different compressibility of the SS jacketed and the

spiral wound portion of the gasket.

Additionally, leak was observed from the joint between

end flange and the channel head flange. On opening it is

observed that channel head lower flange and end flange





has eroded by 2-3 mm at multiple locations, which was

not observed earlier. Thus, bottom flange of the channel

head was built up with suitable welding filler.

Similarly, the end flange after metal build up activity was

carried out at end flange adjacent to channel head bottom.

Then, in-situ machining was carried out at the of the

partition plane of the bottom flange of the channel head

and at the end flange side.

Then the exchanged is boxed up with SS jacketed with

outer spiral wound gasket and then taken inline. This time

temperature has successfully dropped below 50OC and is

sustaining from 17/01/19 till date.





Results:

1. After installation of gaskets and box-up with above

modifications, the outlet temperature of oxidized

caustic/ vapor mixture from 116-EE-802 has been

achieved at 28OC.

2. Due to drop in outlet temperature of oxidized

caustic/vapor mixture coming from 116-EE-802, now

the pH can be more accurately measure/controlled,

hence proper neutralization of the waste going to

waste water treatment plant can be achieved.

3. Through neutralization of waste, material erosion in

piping and static/rotating machinery can be avoided.

4. Hence the performance of WAO process cooler of

Ethylene Cracker Unit (ECU) of BCPL, Lepetkata

has been restored.

6. Target Date for Completion: 15/02/2019

7. Potential Benefits:

a) Tangible:

1. Reduction in maintenance cost.

2. Now no requirement of additional water to be sprayed

in the outlet line to achieved the desired temperature.

3. Improved housekeeping of the area due to external

water spraying.

b) Intangible: 1. After the modification, the heat exchanger is working

as per design parameters.

2. Frequent maintenance of the heat exchanger has been

minimized.

8. Achievement till date: The waste water system performance of ECU has been

restored through control in outlet temperature of the

oxidized caustic/vapor mixture.

9. Implementation Status:

Implemented: YES / NO

If NO, reasons:

Yes, implemented.

10. Counselor’s Remarks: Not required.


QUALITY CIRCLES: SHARING THE SUCCESS STORY ’18-19



Forwarded to: Total Quality management Group

1. Name of the work center: BCPL

(Project registration. no. BCPL/LEP/MECH/ECU/QC/03 dated 15/02/2019)

2. QC Team Name: Explorer

Team Leader : Mr. Ranabir Tarat

Members : Md. Kalamuddin

Mr. Nabajit Das

Mr. Nitul Kalita

Mr. Pankaj Kumar


Mr. Angshuman Gogoi

Mr. Chandan Dowari


3. Champion/HOD: Mr. Pranjal Kakoty / Mr. R. P. Singh

4. Project Title: Performance restoration of WAO Process Cooler of Ethylene Cracker Unit

of BCPL, Lepetkata.

5. Reason for selecting the project:

WAO process cooler (116-EE-802) was unable to cool the mixture of oxidized caustic/vapor.

Thus, this hot mixture remains corrosive and erodes the waste water neutralization drum and its

associated downstream piping, pump and heat exchanger.

6. Outcome of the project/suggested modification or improvement:

1. After installation of gaskets and box-up with above modifications, the outlet temperature

of oxidized caustic/ vapor mixture from 116-EE-802 has been achieved at 28OC.

2. Material erosion in piping and static/rotating machinery can be avoided.

3. The performance of WAO process cooler of Ethylene Cracker Unit (ECU) of BCPL,

Lepetkata has been restored.

4. In future tube bundle and channel head with proper provision for gasket placement shall

be ensured so that inter pass leak does not arise.

7. When from solutions/counter measures were implemented: 17/01/2019

8. Effectiveness of implementation:

After the modification, the heat exchanger cooling effectiveness has been restored.


QUALITY CIRCLES: SHARING THE SUCCESS STORY ’18-19



Forwarded to: Total Quality management Group

9. Tangible benefits achieved:

1. Reduction in maintenance cost.

2. Now no requirement of additional water to be sprayed in the outlet line to achieved the

desired temperature.

3. Improved housekeeping of the area due to external water spraying.

10. Intangible benefits achieved:

1. Frequent maintenance of the heat exchanger has been minimized.

2. Due to drop in outlet temperature of oxidized caustic/vapor mixture coming from 116-EE-

802, now the pH can be more accurately measure/controlled, hence proper neutralization

of the waste going to waste water treatment plant can be achieved.

3. Through cooling the corrosive effect oxidized caustic/vapor mixture shall reduce which

helps in reduction of erosion in piping and static/rotating machinery involved in the

associated downstream system.

11. Is there any opportunity of horizontal deployment in other departments or work center(s):

This type of job in case of heat exchanger may be implemented when it is not possible to

dismantle due to physical position of the equipment.

Also, method of correction shall be based on physical properties of the working fluid such as

pressure, temperature and corrosive nature etc.

BRAHMAPUTRA CRACKER & POLYMER LIMITED Quality …...temperature drop of oxidized caustic/vapor...

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