What is the impact of the injection location of spent alkali on acidic water operations?
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What is the difference between injecting the waste alkaline solution generated by the upstream units of petrochemical enterprises into acid water storage tanks and injecting it into acid water stripping towers? What are the respective impacts?
Difference: After being injected into the large tank and mixed with acidic water, there is a natural reaction time, but it is not possible to control the average injection concentration, making adjustments difficult. Moreover, the mixing of the alkaline solution within the tank cannot be uniform; the impact is minimal when the amount used is small, but it becomes more significant when the amount is larger. Additionally, when the waste alkaline solution contains oil phases or impurities, the properties of the raw water fed into the tower can change significantly over time, which has a considerable impact on the stripping tower. Of course, some impurities can settle to the bottom of the tank, which is better compared to introducing them directly into the system. The injection amount into the stripping tower or feed can be controlled; it can be adjusted or stopped depending on the quality of the purified water and the parameters of the tower system. Of course, there are some differences between injection into the stripping tower (including the injection point) and injection before the heat exchanger.
Are there any literature reports or research materials on this topic?
1. Detailed information on this topic can be found in the books \"Sulfur Recovery Technology and Engineering\" and \"Q&A on Sulfur Recovery Unit Technologies\".
If the spent alkali is poured directly into the large tank, the sulfides removed through wastewater stripping cannot be eliminated and thus do not form fixed sulfur, resulting in purified water that does not meet the standards. This was exactly what happened when our company’s second phase of operations began; as a result, the purified water was of substandard quality for a week. If it is added to the towers – specifically, the ammonia removal towers in the dual-tower system – then as long as the pH is above 8, the fixed ammonia in the purified water can easily be converted back into free ammonia, allowing the purified water to meet the standards