Organic, anorganic acids as combustion product removers

Anorganic acids: HCl traces trapped in crystals. It would bind the potassium products.
H2SO4 - can not be added, but can be created on place by burning sulphur, sulphur needs a catalyst to reach oxidation state VI - such as V2O5.

HOOC-COOH - oxalic acid, a pretty strong one, melting point 101°C, flash point 166°C.
citric acid - melting point 153°C, decomposition at 175°C.
acetic acid - only in solutions, flash point 43°C
tartaric acid - melt point 170°C, many stereoscopic forms, dicarboxylic acid, pretty strong