Eskom - Duvha Power Station - Boiler External Cleaning

Boilers: Cleaning system

03-01-2013

Jaco van Zyl

Coal ash

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Coal Ash

Definition

•Waste left after coal is combusted (burned)•Includes fly ash which is carried up the smoke stack, captured by pollution controlled devices•Include coarser materials that fall to the bottom of furnace

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Coal Ash

Coal ash contains heavy metals including the following

Arsenic, Lead, Mercury, Cadmium, Chromium, Selenium, Aluminium, Antimony, Barium, Beryllium, Boron, Chlorine, Cobalt, Maganese, Molybdenum, Nickel, Thallium, Vanadium and Zinc

Why dangerous

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Coal Ash

Problematic effects

•Health issues•Mechanical defects•Electrical defects

Health issues

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Safety at work

The expert in biological weapons

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Health issuesIf eaten, drunk or inhaled, the toxicants can cause

• Cancer impacts• Nervous system impacts such as

• Cognitive deficits• Developmental delays• Behavioural problems

• Heart damage• Lung disease• Kidney disease• Reproductive problems• Gastrointestinal illness• Birth defects• Impaired bone growth in children

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Health issues

Coal ash is dangerously toxic and poses a threat to human health.

The leakage and blowing of toxicants should be controlled.

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Health issues

Mechanical defects

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Safety at work

The shipyard mechanics

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Mechanical defects

• Coal ash enters small spaces, difficult to reach and clean properly

• This is problematic for mechanical devices• All moving mechanical devices from the 0m level up to the

80m level needs more maintenance than usual because of this coal ash

• The coal ash enters everywhere and all moving parts wear and tear.

• All mechanical devices around the boilers are very dirty• Mechanical devices include

• Soot blowers, gears, mills, fans, pumps, motors, etc.

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Mechanical defectsSoot blowers

Electrical defects

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Safety at work

The electrician The power cable installer

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Electrical defects

• Similarly to mechanical defects, the coal ash enters everywhere

• The covers over the electrical boards is not effective enough• The coal ash and dust enters small, fine electrical devices and

wiring• The coal ash can conduct electricity and whenever this

electrical field comes in contact with earth, earth leakage occur (short circuit)

• Because of the short circuits, it can cause transformers to trip• Electrical devices include

• Precip boards, all electrical boards, Mv rooms, Lv rooms, service transformers, etc.

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Electrical defects

Cleaning system

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Cleaning system

• Current cleaning system• Previous cleaning system• Concepts for new cleaning system

Current cleaning system

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How• Women with feather dusters dusting the boilers

and other devices• Men with brooms cleaning the floor on each level• Each unit is cleaned from the 80m level down to

the 16m level

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Advantages• Cost effective• No water or electricity are used

Disadvantages• Time consuming• By the time the 16m level of a specific unit is

cleaned, that specific unit’s 80m level is dirty again

• Because of the feather dusters, the coal ash escapes into the air and will go and sit on another place

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• The current cleaning system is ineffective• A specific unit will never be completely clean, because of

the coal ash escaping into the air which sits on other places, sometimes hard to reach.

• The coal ash in the air will go and sit on mechanical equipment which can cause mechanical failure. Likewise, the ash goes and sits between fine electrical wiring, which can lead to electrical defects.

• Another, more effective cleaning system is required

Conclusion

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Safety at work

The grinder

The welder

Previous cleaning system

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Previous cleaning systemHow

Vacuum cleaning system• Every level has infrastructure for the vacuum cleaning for

that specific level• A vacuum turbo blower system is situated on the 0m level

which is linked to each level by pipes• Workers link vacuum pipes to pipes situated on each

level which are linked with the vacuum turbo blower as discussed above

• The coal ash gets vacuumed and is being transferred to an ash silo

• This silo’s bottom is linked to a water source and gets pumped into the same grinder which grinds the water and fly ash and water and coal dust mixture which will then be transferred to the ash dams

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Advantages• Time efficient• Complete cleaning of a specific unit is possible• All ash gets vacuumed. No ash escapes like in

the case if feather dusters are usedDisadvantages

• Motor breakages• Pipe blockages• Water and electricity are used

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Vacuum turbo blower system

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• The previous cleaning system was effective and very time efficient

• The only setback of this system was the pipe blockages and the motor breakages. The time spent on maintenance on this system was inappropriate

• If a solution can be found for all of these problems, this system will be effective and will be strongly suggested to re-implement this previous cleaning system

• With the infrastructure already in place, no extra cost will be made for the infrastructure

Conclusion

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All infrastructure of the previous cleaning system is still located on each unit

Infrastructure

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Infrastructure

• Four pipes around boiler on each level from the 16m level up to the 80m level

• These pipes joins each other at the “coal ash silo” on the 0m level

• The pipe on the bottom of the silo gets connected with water and gets transferred to the grinder

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Infrastructure

80m level

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Infrastructure

57m level

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Infrastructure

33m level

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Infrastructure

16m level

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Infrastructure

0m level

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Infrastructure

0m level

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Infrastructure

0m level

Concepts

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Concepts

• Previous cleaning system with improvements• Mobile cleaning system

Previous cleaning system with improvements

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How• Exactly the same as previous cleaning

system• Improvements will be made

• Filters to eliminate pipe blockages• New improved motors with less problems

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Advantages• Time efficient• Almost complete cleaning is possible• Infrastructure already in place• No health problems, mechanical or electrical

defectsDisadvantages

• Water and electricity are used• Pricy because of new motors

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• Very effective system• With no pipe blockages, system will operate perfect• No extra cost for new infrastructure• Only one unit’s cleaning system can be revamped

• Cleaning of the pipes from the 80m level down to the 16m level

• Implementation of filters to eliminate pipe blockages

• New motors for specific unit• This system will create a clean working environment

Conclusion

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Safety at work

The paintersThe city council maintenance team

Mobile cleaning system

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How• Similar to previous cleaning system• Improvements will be implemented

• Filters for pipe blockages• Motor vacuum system on a mobile trailer• Mobility to all units are possible

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Advantages• Time efficient• Almost complete cleaning is possible• Infrastructure already in place• No health problems, mechanical or

electrical defectsDisadvantages

• Water and electricity are used• Pricy because of new motors• Travel from one unit to another

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• Very effective system• With no pipe blockages, system will operate perfect• No extra cost for new pipe infrastructure• Units cleaning systems must be revamped

• Cleaning of the pipes from the 80m level down to the 16m level

• Implementation of filters to eliminate pipe blockages

• New vacuum motor system for mobile trailer• Vacuum motor system similar to previous system• Trailer needed

Conclusion

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Conclusion

• Pricy at start because new, but• Only one mobile vacuum system• Less expensive than previous system• Time efficient maintenance and less maintenance,

because only one system• A second mobile vacuum system may be implemented

in the future• This system will create a clean working environment

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Safety at work

The construction site worker The mason

Conclusion

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Conclusion• If all the problematic effects namely health issues, mechanical defect

and electrical defects are considered, a more effective system needs to be introduced

• This project must be looked at and must be taken further in the near future

• Things which can be looked at in the near future• Cleaning the vacuum pipe infrastructure to eliminate all possible

blockages• Motor/ turbo blower availability• Filter availability for vacuum pipes• Flexible pipes for vacuum cleaning on each level and connections

to the vacuum pipe infrastructure• Mobile cleaning system design• Only redoing one unit to test for effectiveness

• The previous system worked perfectly. With improvements, a similar system will work even better.

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Cleaning system

Any Questions??

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Cleaning system

Thank you

Eskom - Duvha Power Station - Boiler External Cleaning

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