Procedure for Boiler Gauge glass line up & Flushing

Boiler Gauge glass: is a transparent glass of shape tubular, flat or square blocks fitted to the boiler steam drum to facilitate a visual indication of the water level of a steam drum. These types of glasses are manufactured by borosilicate glass which is robust, temperature & chemical resistant.

 



Line up of Gauge glass:

  • Ensure all tools & required PPEs are taken to operate the valves (Hand gloves, Safety goggles, “F” rods etc)
  • Ensure steam & water side valve of gauge glass are healthy & operating properly
  • Ensure there are no any leakages
  • Ensure steam side & water side valves are closed
  • Ensure gauge glass drain valve is open & drain is connected/extended to safe location
  • Now crack open the steam valve & check for any leakages in gauge glass. Wait for some times until system heats uniformly.
  • Then crack open the water side valve, wait for some time for stabilization
  • Then close the drain valve
  • Open the steam valve & water valve fully
  • Observe water collected in glass & showing the level
  • Cross check the level glass with other side level glass or control room transmitter reading or with Hydra step

Factors considered for Boiler Engineering

Flushing of gauge glass

Ensure all tools & required PPEs are taken to operate the valves (Hand gloves, Safety goggles, “F” rods etc)

Step-I

  • Close the water side valve & open the drain valve for flushing, wait for some time
  • Then close the drain valve & open the water side valve

Note: After opening the water side valve, water level should retain its normal operating level, if not then there might be blockages in valve or line

Step-II

  • Close the steam side valve & open the drain valve for flushing, wait for some time
  • Then close the drain valve & open the steam side valve

Note: After opening the steam side valve, water level should retain its normal operating level, if not then there might be blockages in valve or line

Questions & Answers on AFBC Boiler





10-tips to reduce LOI/unburnt in Boilers

 

 1-Optimization of fuel moisture in the fuel:

Higher moisture in the fuel leads to unbalanced draft in the furnace or combustion chamber. Which ultimately results into poor mixture of air & fuel, higher moisture fuel demands more excess air. So optimization of fuel moisture will help to reduction in LOI.

2-Maintaining balanced draft in furnace:

Unbalanced draft is nothing but more FD air/less ID draft or less FD air /More ID Draft.

More FD & less ID causes back fire & improper mixing of air & fuel.

More ID & less FD causes escape of fuel particles from furnace without proper combustion

3-Maintaining 3Ts of combustion:

3Ts of combustions are: Temperature, Time & Turbulence

Temperature: For proper combustion temperature of the furnace must be sufficient enough to burn the fuel completely.

Time: There must be sufficient time for combustion

Turbulence: There should be proper turbulence in furnace for proper mixing of air & fuel

4-Increasing the secondary air quantity & pressure:

This will help to increase the residence time of fuel in furnace resulting into complete combustion

5-Maintaining the required excess air:

Lesser excess air than required will lead to incomplete combustion that is conversion of carbon into carbon monoxide instead of carbon di-oxide. So sufficient air is required to achieve complete combustion.

6-Using correct or designed GCV of a fuel:

Lesser GCV fuel requires more air for combustion, even may not achieve the designed parameters of Boilers like flow, pressure & temperature.

7-Ultimate & Proximate analysis of fuel:

In order to achieve proper combustion, we must know the contents of fuel properly. Need to operate the Boilers at designed parameters of fuel. For example if FC of the fuel increases, then need to increase air & combustion time and need to reduce turbulence.

So it is very important to know the fuel contents.

8-Operating the Boilers at stable loads:

Stable loaded Boilers will not lead into much LOI, as air & fuel mixture is constant & will not vary frequently. LOI cannot be reduced in variable load boilers.

9-Operating the Boiler at little positive draught:

Operation of Boiler at positive draught will help for complete combustion. If boiler is operated at more negative draught, then there will be more chances of escaping of unburnt fuel particles from the furnace & causing secondary combustion at super heaters & other convective zones.

10-Reusing unburnt or cinder:

Generally unburnt/cinder from Boiler Bank & economiser zones are re-injected into furnace by using “Cinder re-injection” system. This will help in re-burning of cinder & reduction in LOI

 Procedure for Boiler Gauge glass line up

 

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