The function of the graywater preheater
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The ash water at around 110°C, coming from the deaerator in the Texaco water-coal slurry gasification process, is heated to around 179°C through heat exchange with the gas exiting the high-pressure flash tank in the ash water preheater, before entering the bottom of the carbon scrubbing tower. Why is it necessary to preheat graywater?
This gray water is sent to the carbon scrubber – isn’t it true that the lower the temperature, the better?
Obviously, the lower the temperature, the better it is not, as conversion systems generally require a certain water vapor ratio; too low a temperature will result in an excessively low water vapor ratio. This is my personal understanding.
The lower the temperature, the better. Which expert holds this view?
Isn’t it going to the carbon scrubber to wash the crude syngas? Lower temperatures are necessary to more effectively remove fine residues from crude methanol gas
So what is a suitable water vapor ratio for the syngas going into the transformation? Is about 1 a bit small?
To recover waste heat, the conversion section needs to generate a higher water vapor ratio in order to reduce energy losses
This path leads to the carbon scrubbing tower; the temperature rises after passing through the graywater heater, and this is done mainly to recover heat, maintain thermal balance in the system, and reduce heat losses. For the syngas coming out of the scrubbing tower, it’s not true that the lower the temperature, the better – it generally should not be below 220 degrees Celsius. A lower temperature results in a lower water vapor ratio. However, in the shift unit, the syngas still needs to be preheated, so that its temperature inside the shift reactor is higher than the dew point temperature of water at that pressure, thereby preventing water vapor from condensing inside the reactor. Thinking in this way makes it understandable. It’s just my personal opinion; I hope everyone can point out any mistakes.
The main purpose of this section is not slag removal.