Brahmaputra Cracker & Polymer Limited Quality Circle Projects


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BRAHMAPUTRA CRACKER & POLYMER LIMITED
QUALITY CIRCLE PROJECTS: STATUS REPORT

WORK CENTER: BCPL INTEGRATED OFFSITE PLANTS (N2, CT, ETP, DM, RWTP) AS ON: 28.08.2018

1. QC Registration No.
2. QC Team Name
3. a. Team Leader b. Team Members

BCPL/LEPK/MECH/IOP/QC/2018-19/01
ANPRAJAH
Anirvan Chakrabarti
1) Prakritij Hazarika, Mgr. (Mechanical) 2) Jahnab Jibon Choudhury, DM (Mechanical) 3) Debabrat Das (Foreman) 4) Chandra Doley (Foreman)

4. Champion/H SRI MAHIM KONWAR , DGM (MECHANICAL)/ SRI RAJPAL SINGH,

OD

GM(PE)

5. Improvement PROJECT TITLE: REDUCTION IN DOWNTIME OF OILY AND

Project

CHEMICAL SLUDGE CENTRIFUGE EQUIPMENT TAG NO. -

149-G-01

Introduction: Principally, a Centrifuge is nothing else than a thickener, which rotates about an axis and which is equipped with an inlet and an outlet and emptied by a continuously operated screw conveyor. Providing the theoretical rotating thickener with a cylindrical and conical bowl section as well as a screw conveyor, serving for continuously emptying the settled solids, the result will be a centrifuge with large output volumes and rapid clarifying effect – i.e. continuously-operated solid-bowl screw centrifuge.

The feed material reaches a feed compartment via a feed pipe. Inside the compartment the material is accelerated, i.e. brought to operating speed and then enters the rotating bowl by openings. In the first BOWL section, i.e. the CYLINDRICAL SECTION, the solid particles are moved to the bowl wall under the effect of centrifugal force. This process being called

Team Leader

Champion/HOD

CLARIFYING and the centrifuge section being called CLARIFYING ZONE. The solids separated by centrifuging are transported by the SCREW CONVEYOR, rotating at a different speed than the bowl, to the discharge openings via the conical section. On their way to the discharge openings, the solids are subjected to further dewatering, especially in case the solids are removed from the liquid in the conical bowl section. This section of the centrifuge is called the DEWATERING ZONE.
The Oily and chemical Sludge Centrifuge (Tag No.: Tag No.: 149-G-01, Model No.: S1-11, OEM: MBE Coal & Minerals Technology India Private Limited/ Humboldt Wedag India Private Limited M/s Humboldt Wedag Minerals India Pvt. Ltd.)is a standard Solid-Bowl Screw Centrifuge, operated by the Counter-Current principle. The counter-flow means that the solids settled in the settling zone move oppositely to the liquid separated. It is an important equipment for separating thickened sludge and water coming from the Oily and Chemical Sludge sump. There is only one Centrifuge in ETP catering this requirement without any stand-by equipment. Though the equipment is run on as-and-when required basis, yet it plays an important role in the effluent treatment process. Keeping in view of the same, it is imperative that the performance of the Centrifuge is very critical and important for efficient functioning of the overall ETP.
Defining the problem: During normal operation of the equipment, high vibration and noise was found in the equipment and the centrifuge got tripped due to high power consumption. Upon preliminary inspection of the equipment, one of the supporting lugs of the conveyor cylinder outer cover was found broken. It was suspected that several other components of the centrifuge might have been affected due to sudden rupture of the support lug and sudden rise in vibration of the equipment. Furthermore, when referred to the Equipment history record of the equipment, it was found that rise in vibration and rupture of the conveyor drum support lugs occurred several times in the recent past. Also drop in performance of the equipment was noticed as it was unable to form proper sludge cakes as it supposed to. Therefore, the equipment was decided to be taken under maintenance and overhauled.
Hence based on the facts and observation “REDUCTION IN

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Champion/HOD

DOWNTIME OF OILY AND CHEMICAL SLUDGE CENTRIFUGE” is selected as problem.

Analyzing the problem:

4W 1 H Method

What
Where When
Who How

REDUCTION IN DOWNTIME OF OILY AND CHEMICAL SLUDGE CENTRIFUGE Effluent Treatment Plant During normal operation of centrifuge ETP operator Will be analyzed in step -4 ( root cause analysis)

Identifying the causes: Fish Bone analysis.

MAN

Material

Breakdown in Centrifuge

Machine

Method

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Champion/HOD

Identifying the Causes:

SL no 1 2
3

Man Lack of Training. Lack of proper Skill.

4 5 6
7 8

Machine High Vibration in the equipment High ampere during loading.
Jamming of conveyor screw
Damage of fluid coupling Damage of bearings Damage of hypocycloid gearbox High V-belt tension Damage of motor/coil damage/bearing damage

Material Improper feed No pre and post flushing with water Use of improper lube oil in fluid coupling

Method Inadequate lubrication Insufficient feed
High oil level resulting in high starting torque

Finding out the root causes:

Sr. Cause
No.
1 Lack of Training.
2 Lack of proper skill
3 High Vibration in the equipment

Why 1
Damage of casing support lugs

Why 2
Damage of rubber buffers

Why 3
Damage of NDE/DE and gearbox/coupling components

Root cause
Training Schedule
Improper training
Weakening of support lugs/rubber buffers, expiry of self-life of bearings

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Champion/HOD

4 High ampere drawn during loading.
5 Damage of fluid coupling
6 High oil level resulting in high starting torque
7 Damage of hypocycloid gearbox
8 Damage of motor/coil damage/bearing damage
9 Improper feed
10 No pre and post flushing with water
11 Use of improper lube oil in fluid coupling
12 Inadequate lubrication

Excessive Rubbing between conveyor screw and casing. Dry run
Inadequate lubrication
Overheating of motor
Excessive opening/closing of valves
Failure of lubrication system

Jamming of conveyor screw
Bearing and oil seal damage
Development of excessive bearing play
Voltage fluctuations
Inadequate dosing of DWPE
Use of inappropriate grease

High V-belt tension
Fusible plug damage
Damage of roller and cam disc Expiry of self life of bearing
Damage of felt lining in Plummer Block

Damage of bearings, improper flushing of screw and excessive tightening of V-belt Dry run of fluid coupling due to oil leakage from damaged oil seal/fusible plug port
Lack of SMP
Insufficient lubrication, improper clearance between gearbox hubs. Continuous running in high load leading to localized high temperature Lack of proper SOP
Lack of proper SOP
Inadvertent mistake
Jamming of lubrication ports and change in

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Champion/HOD

13 Insufficient feed

Low pump discharge

Line choking Excess bypass valve opening

viscosity due to water ingress and increase in localized high temperature Improper priming

Data Analysis:

Data is collected on all the probable causes and Pareto chart is prepared based on the same.

Sl.

Causes

Frequency Cumulative Percentage Percentage

No.

Frequency

of

of

Individual Cumulative

Frequency Frequency

1 High ampere 18

18

25%

25%

drawn during

loading.

2 No pre and post 15

33

21%

46%

flushing with

water

3 High Vibration 13

46

18%

64%

in the

equipment

4 High oil level 9

55

12.5% 76.5%

resulting in

high starting

torque

5 Damage of

7

62

9.7%

86.2%

fluid coupling

6 Damage of

4

66

5.5%

91.7%

motor/coil

damage/bearing

damage

7 Inadequate

3

69

4.2%

95.9%

lubrication

8 Insufficient

2

71

2.8%

98.7%

feed

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Champion/HOD

9 Improper feed 1

72

1.3%

100%

10 Damage of

0

72

0%

100%

hypocycloid

gearbox

11 Use of

0

72

0%

100%

improper lube

oil in fluid

coupling

14 Lack of

0

72

0%

100%

Training.

Pareto Chart:
25% 20% 15% 10%
5% 0%

Percentage of Individual Frequency

Developing Solution: From the Pareto chart it is clear that major reason for breakdown of Oily

Team Leader

Champion/HOD

and Chemical sludge centrifuge are

i) High ampere drawn during loading ii) No pre and post flushing with water and iii) High Vibration in the equipment

Brainstorming Tool is used for deriving the counter measure of Root

causes.

SL No Root Cause

Counter measure

1

High ampere drawn during Bearings replacement, Proper flushing

loading

of screw and proper tensioning of V-belt

2

No pre and post flushing Display and follow of SOP

with water

3

High Vibration in the

Repair of existing support lugs

equipment

Providing additional support lugs

Replacement of rubber buffers in

baseframe if required

Inspection of fluid coupling, gearbox

and replacement of bearings and

damaged components

Foreseeing probable Resistance: No resistance is faced.

Trial Implementation :
After replacement of all the damaged parts and greasing of the rotating components, the centrifuge was made ready on 18.08.2018. However, upon first two trials the centrifuge tripped due to high current consumption. Upon referring the O&M manual and also after consulting OEM, oil level in the fluid coupling was lowered upto 50 % level and test run was done. The centrifuge was started in NO-LOAD condition and this time the current consumption was 16 Amps. Gradually the centrifuge was taken under load and was kept under observation for prolonged period. OEM vendor M/S Humboldt had visited site from 19.08.2018 to 21.08.2018 for observing the centrifuge during this period and inspect for any persisting abnormality in the equipment from his end. However, all running parameters of the equipment including vibration and sound were found considerable by OEM vendor. Centrifuge has been running satisfactorily since then with current consumption of 22 Amps under full load condition.

Team Leader

Champion/HOD

BEFORE

AFTER

UNIT EQUIPMENT DESCRIPTION
OPERATING SPEED

JOB DETAILS:

:

IOP

:

OILY AND CHEMICAL SLUDGE

CENTRIFUGE

:

2900 RPM

The following sequential maintenance activities were carried out in the centrifuge, its
gearbox as well as in the fluid coupling:
1) The broken support lug for the outer cover was welded and repaired. Four nos. of additional such supports were provided at all four corners of the cover beside the existing ones for providing rigidity to the cover and prevent such failures in future.
2) Centrifuge NDE bearing 6222MAC3 was replaced with new spare bearing. As the DE and NDE ball bearings are the primary load carrying bearings of the centrifuge conveyor and these bearings aren’t readily available in store, therefore spare bearings were immediately procured and kept in stock to cater future requirements.
3) One needle bearing no. TAF 9011025 at DE of the conveyor shaft was replaced
with new spare bearing.
1) One damaged metallic sealing ring L24-04-80 in centrifuge bearing cover was found damaged.
4) 2 nos. of O-rings and one fellet ring DN5419 at the DE of the conveyor bearing

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Champion/HOD

cover was replaced with new available spare parts. 5) Oil seal 55-72-10 in fluid coupling was replaced with new spare seal and also
damaged fusible plug was replaced with available spare plug. 6) One damaged combined needle+ball bearing in the fluid coupling was replaced
with new bearing. 7) One damaged ball bearing 6307 at the NDE inside the cyclo gearbox was
replaced with new bearing. 8) Play found in two ball bearings 6015 and 6215 inside DE of the cyclo gearbox
was replaced with available new set of bearings. 9) All Plummer block felt seals were replaced with new strips. 10) 6 nos. of damaged Allen casing bolts were replaced with new bolts and
complete casing gasket was replaced with new gasket.
REMARKS: After replacement of all the damaged parts and greasing of the rotating components, the centrifuge was made ready. The centrifuge was started in NO-LOAD condition and this time the current consumption was 16 Amps. Gradually the centrifuge was taken under load and was kept under observation for prolonged period. All running parameters of the equipment including vibration and sound were found within the limits. Centrifuge has been running satisfactorily since then with current consumption of 19 - 20 Amps under full load condition. Cake formation was found to be normal.

6. Target Date for completion
7. Potential Benefits Tangible
Intangible
8. Achievement Till Date

28.08.2018
1. PROPER OILY SLUDGE CAKE FORMATION 2. EASY DISPOSAL OF SLUDGE 3. SMOOTH OPERATION OF EQUIPMENT AND REDUCTION
IN POWER CONSUMPTION 4. INCREASE IN AVAILABILITY OF THE EQUIPMENT
REDUCTION IN SPREADING OF HAZARDOUS WASTE IN THE ENVIRONMENT
Regular implementation completed and Follow up/Review under progress.

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Champion/HOD

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Brahmaputra Cracker & Polymer Limited Quality Circle Projects