Issue of the size of the circulation tank in the tail chlorine absorption system for producing sodium hypochlorite
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Dear Haihao friends: For the construction drawings of the ion-exchange membrane caustic soda project we have designed, the system for absorbing residual chlorine to produce sodium hypochlorite is designed as a dual-tower, four-tank system. During the expert pre-review, it was pointed out that the volume of the alkali solution circulation tank in the waste gas absorption system for producing sodium hypochlorite is too small, which does not comply with **safety standards. May I ask, are there any standard requirements regarding the size of the sodium hypochlorite circulation tank? Are there specific volume requirements? Urgently need it online; thanks to the expert for helping!
The last edit to this post was made by wuyifeng on 2017-8-30 at 18:52. 1. In the design of chlorine generation systems, the chlorine produced when the electrolyzer operates at full capacity for 15 minutes should be completely absorbed by the fresh 15% alkaline solution in the preceding accident tower, so that no chlorine escapes and there is no overheating； 2. If possible, a high-level tank can be added to ensure reliable spraying due to its own weight in the event of a power outage. 3. It is recommended to use remote switching for switching to the backup slot. 4. For the cyclic absorption of alkaline solution, it is recommended to use online ORP monitoring to determine the concentration of the alkaline solution.
In my opinion, what was said on the second floor is correct; from a design perspective, design institutes will calculate the amount of chlorine required for 15 minutes of full-scale production, and the designs generally meet the relevant regulations. But from your words, I understand that your factory classifies this device as a sodium hypochlorite production unit, while the experts believe it is an environmental protection device. Under normal production conditions, sodium hypochlorite is also being produced; in the event of an accident, the semi-finished sodium hypochlorite tanks certainly cannot meet the design requirements for absorbing chlorine in such situations. It is recommended to use a euphemistic definition, such as an environmental protection device for absorbing chlorine in accidents, rather than one for absorbing exhaust gases.
Is it the case that the experts believe the small volume of the alkali solution circulation tank is insufficient to meet the requirements for absorbing waste gases?
The circulation tank now needs to be modified, and its size must be redesigned. Which standards should we use to calculate its volume? The space available in the installation area is limited, and the management wants the tank to be as small as possible!
AQ/T 3016—2008: Check out this standard for safety in the chlor-alkali industry; it contains specific requirements.
Hello, the ORP meter is used to measure free chlorine in alkaline solutions. What is the relationship between this value and the concentration of the alkaline solution?
One has to figure out the corresponding relationship on their own; it depends on factors such as the concentration of the alkali used and the circulation temperature. It is best to keep the temperature relatively constant, and if the concentration of the alkali solution used initially remains constant, it will be possible to monitor the situation effectively. In our company, the alkali concentration is 15%; it is around 3% when the ORP is about 490, and below 1% when the ORP is around 520.
Based on the maximum leakage volume in case of an accident at the facility, it is sufficient to be able to collect the flow under full load for 10–20 minutes, which will ensure complete absorption