Seeking advice on the problems encountered with direct steam ammonia vaporization
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At our plant, we are currently using sieve plate towers for the direct vaporization of ammonia using low-pressure steam. The problem we are facing is that the trays in the ammonia vaporization tower get clogged frequently, and the wastewater flow path in the ammonia-water heat exchanger (of spiral plate type) is also completely blocked. There is a ceramic membrane filter for removing excess ammonia at the inlet side. We suspect that the clogging of the trays is related to the addition of alkali; the alkali is added directly to the ammonia water after it has been heated, without the use of any piping mixers. Have other colleagues encountered such a problem? Or is there a better way to solve it!
Have the levels of hydrogen sulfide and chloride ions increased?
I think either too much alkali was used, or the raw water contained high levels of calcium and magnesium ions. It’s necessary to make some modifications; start by desalinating the water first
How is the tar discharge at the bottom of your tower? . . Is there air flotation for oil removal? . Considering the analysis of the wastewater COD levels, it seems that your wastewater contains too much tar
Add pipeline mixers and clean blockages regularly
Regular sieve plate or vertical sieve plate? It is recommended that you use vertical sieve plates
The location for adding alkali is incorrect; it would be sufficient to modify the alkali addition pipeline at the inlet for the remaining ammonia water in the ammonia distillation tower. However, the upper trays of the ammonia distillation tower still tend to get clogged after prolonged operation. It’s best to check whether there is a leak in the cooler, as this could cause circulating water to mix with the circulating ammonia solution, resulting in an increase in calcium ions in the remaining ammonia solution