Preheat water to be boiled before entering boiling chamber

Hi, I'm a degree student currently taking Mechanical Engineering
I have a question regarding the power plant design
If I have to cool down the ash produced inside the chamber(which used to heat up the water), can I use the water from the red arrow as shown in the attachment, to 'preheat' the water before it enters the tube to be boiled besides 'cooling' the ash?
Thanks for all the advises.

Using water to cool the ash would require pipes to be in contact with moving ash. Ash can be very abrasive so what material would you use for the pipes if they were to have a reasonable life span before having to be replaced ?

In a well designed furnace the heat from the ash leaving the furnace can be used to preheat the air going into the furnace.

bernardgreen said:

Using water to cool the ash would require pipes to be in contact with moving ash. Ash can be very abrasive so what material would you use for the pipes if they were to have a reasonable life span before having to be replaced ?

In a well designed furnace the heat from the ash leaving the furnace can be used to preheat the air going into the furnace.

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what is the material used in the transport the flying hot ash? can we just use that material? so that the lifespan will be same?
can i preheat water instead of air? any idea regarding this?