There are many methods used for optimization of wall blower operation, like the manual method, heat flux measurement method, and the automated method. The manual method is discussed as this will bring out the philosophy involved in optimizing wall blower operation.
Need for wall blower optimization
- To improve consistency in efficient operation of boiler
- To reduce steam wastage by identifying those areas of low or no deposits
- To reduce damage on furnace wall tubes due to excessive blowing
The change in SH spray without change in other parameters indicates that the furnace deposits are increasing. If the superheater spray increases above a particular level (to be determined for each boiler) operate wall blowers. These are two basic things to adhere to while optimising wall blowers.
Steps in wall blower optimisation
Assuming there are 88 wall blowers in a boiler furnace wall, the steps for optimisation is listed.
- Operate all 88 blowers
- See the effect on superheater spray and note all operating parameters of boiler
- Wait for the superheater spray to ramp up to the initial level and stay almost steady
- Wall blow each row - study effect
- Watch superheater spray drop and regain time
- The interval between blowers is to be maintained constant
- Repeat if required each row independently, waiting each time for the spray to reach the original level with other parameters of boiler remaining constant
- Repeat the study for two adjacent rows
- Repeat the study for two alternate rows
- Repeat the study for blowers in front, rear, left and right sides of furnace walls separately and study the effect on superheater spray flow.
- The blowing having the least effect on the superheater spray indicates low or no deposit on the walls.
- A plot of superheater spray drop when each blower is operated will give a good idea of deposition in that area
- Use the photograph of the furnace wall to validate the effectiveness of blowers
- Decide which blowers can be skipped during blowing as well as the effectiveness of the row
The procedure for wall blower operation can be evolved after the study and data analysis for the most effective way of wall blowing.
The use of heat flux meter by embedding thermopiles at appropriate location in the furnace walls to understand whether the tube in the region is clean or with deposition the operation of the wall blower requirement can be decided.
In the case of fully automated intelligent wall blower system, the need to wall blow each blower is understood from the effective heat flux falling on the tubes. Designers use different methods to establish this.