Assessment Of High Concentration Ash Slurry Disposal System

Assessment Of High Concentration Ash Slurry Disposal System

Love Kumar Thawait,

Master of Engineering (Production Engineering) Chouksey Engineering College, Bilaspur,

Abstract – Thermal Power Plants using coal is chief source of energy in our country and it is likely to remain so innear future. The total production of fly ash per annum has already crossed 100 million tones and the disposal of the fly ash is causing several challenges. Utilization of fly ash has picked up but till the percentage utilization is far below satisfaction and power plants are no option but to dispose the fly ash in ash pond. High concentration fly ash slurry is the fly ash disposal system that is followed in many coal based thermal power in India. Efforts to reduce the dilution of the slurry will result in energy conservation as well as water conservation. The latter is even more important to overcome the problem of excess water consumption.

Keyword- Fly ash, slurry concentration, power plant, ash disposal,

INTRODUCTION

Coal fired electricity generating plants produce massive amounts of ash as a waste product of combination. In a pulverized coal unit three kinds of ash are produced. Bottom ash, economizer ash, and fly ash. Bottom ash is the residue that accumulates at the bottom of the furnace. Economizer in hoppers ash accumulates in hoppers under the economizer section of the boiler. Fly ash is carried in the flue gas stream. A typical breakdown is 20% bottom ash, 4% economizer ash , and 76% fly ash. The amount of ash produced is directly related to the amount of inert material present in the fuel and quantity of fuel burned.

Economizer and fly ash is generally collected from the flue gas in mechanical separators or electrostatic precipitators in a dry form Economizer and fly ash can either be wet sluiced or pneumatically blown to a final or intermediate disposal point.Lean phase fly ash slurry disposal systems have been in operation for many years in power stations throughout India. Recent advances in high concentration fly ash slurry pumping systems offer advantages for ash disposal systems by virtue of reducing land and water utilization, and by reducing capital and operating costs.

can be reduced by more than 50%.

1. By discharging from a central ramp or side-hill, it is possible to avoid raising perimeter dams altogether.

2. The self-draining, sloping (2-6%) deposit offers long- term stability and can be reclaimed progressively at minimum cost.

3. Significant cost savings in disposal area and dyke construction of up to 60%.

4. Method allows for the creation of small hills by stacking the disposed ash.

5. Extending life time of existing landfill area under restricted slurry conditions.

DISADVANTAGES OF HCSD SYSTEM

1. High capital cost due to the fact that special purpose pumps are required.

2. Very strict quality control on all the processparameters is required to ensure trouble free working of the system.

ADVANTAGES OF HCSD SYSTEM

High concentration slurry disposal system (HCSD system)has more objectives such as:

Ecological

1. Water consumption: high concentration ash slurries use up to a factor 12 less water than dilute slurries.

2. No or minimal contamination by water leaking to the environment.

3. Pipeline transportation is safe, silent and reliable without ash spills.

4. No or minimal run-off water and water reclaim system capacity.

5. Thickened ash is not subject to run-out.

6. Dusting is substantially reduced.

7. Slurry hardens out allowing rehabilitation

Operational

1. Slurry spreads over area due to gravitation. No mechanical spreading or operator intervention required.

2. No return water system.

3. Pipeline scaling eliminated.

4. High availability, low parts usage, low maintenance.

Economical

1. Substantial energy savings to run system.

2. The volumes transported are smaller and pipeline sizes

DESCRIPTION OF PUMP

Crankshaft driven piston diaphragm pump

The principal difference between a piston and a piston diaphragm pump is the genuine diaphragm that protects the piston and liner from the sliding contact with the abrasive slurry. The diaphragm is a pre-mounded design that eliminates elongation of the elastomer. Its long fatigue life

allows for routine annual maintenance to be carried out. The diaphragm position is controlled in either direction of the stroke by adding or removing propelling fluid that fills the cavity between the piston and diaphragm. A guide rod connects to an insert and enables the positioncontrol.

DATA SHEET HCSD PUMP MODEL NO. ZPM 800 (GEHO

Nederland)

SUMMARY

One of the major challenges in ash disposal is to protectthe environment. To manage safe disposal and conform tothe

stipulations it is necessary to have properPlanning, studies/ investigations, method of disposal atdesign stage, implementation stage, and management ofsafe disposal during operating and non-operating stage.

Based on the technology scan and visits/discussionswith experts/utilities/manufacturers it is gathered thatHCSD has several advantages compared to other disposalmethods.

This paper highlights important issues related to HCSD System Most of the observations are based on experience at various power plant.

ACKNOWLEDGEMENT

I take this opportunity to express my profound gratitude & sincere thanks to Professor Jogendra Jangre & faculty of Chouksey Engineering college Bilaspur , for allowing me to publish this paper I acknowledge with thanks to my colleagues for their generous help in the form of discussions.

REFERENCES

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