Corrosion issues encountered in the distillation separation of ethanol and alkaline solutions

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Problems encountered in the distillation separation of ethanol and alkaline solution: 1. The feed material contains 68% ethanol, along with about 30% alkali and water; the remainder is a small amount of cellulose (organic substance). 2. The ethanol content (concentration) in the final product: ≥93% (v/v). The ethanol content in the wastewater discharged: ≤0.05% (wt/wt)； (The concentration of NaOH obtained after separation is 170 g/L, which is approximately 14.5%). 3. Equipment such as the distillation tower, reboiler, condenser, and reflux tank are all made of 304 stainless steel. 4. The reboiler is heated by saturated steam; the pressure of this saturated steam is about 0.5 MPa (150°C), while the temperature indicated by the thermometer at the bottom of the distillation tower is around 107°C. After the raw material enters the distillation equipment, the ethanol separated from the top of the tower is clean and of sufficient purity ； The alkali solution separated from the bottom of the tower also has sufficient purity, but it contains black solid powder, which was identified as a metallic solid. Suspecting stainless steel corrosion, the upper and lower end caps of the reboiler (which is a vertical fixed-tube-sheet heat exchanger) were removed, and it was found that a black layer covered the inner surface of the reboiler as well as the inner surfaces of the heat exchange tubes; no obvious corrosion of the welds could be seen to the naked eye. Question 1: Can 304 be used under these operating conditions, including for the materials of the reboiler and the bottom of the distillation column? ； Question 2: If it is not suitable, what material would be more appropriate, and which parts need to be replaced with that material?