How does the accident water from the tank area get into the accident pool?
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Dear engineers, we are currently designing a third-party liquid chemical storage area with a capacity of 200,000 cubic meters, and an accident pool has been included in the design. How does the water resulting from an accident – after or during a fire – get into this accident pool? The design institute’s explanation is that clean rainwater is allowed to flow naturally toward the accident tank through dedicated channels, and then enter that tank (the issue of elevation differences is not considered here, as the bottom of these channels may be at a very low level, making it difficult for the water to flow into the tank). Our understanding is that after the fire is extinguished, the water in the area enclosed by the cofferdam is directed into the initial rainwater tank, and from there it is pumped into the accident tank (a tee connection is provided between the initial rainwater pipes and the accident tank, with valves used to switch between them). If clean rainwater channels are used to allow water to flow naturally in the direction of the accident pool, could there be a risk of flash fire, thereby spreading the fire to the utility areas?
The elevation of the accident tank should be the lowest; otherwise, how can it be called an accident tank?
The design institute’s explanation makes sense; the accident pool is at the lowest level.
Through the underground sewage system network.
Are the so-called clean rainwater drains located within the tank farm? If it is located within the tank area, a valve assembly can be installed outside the tank area to control the flow, allowing it to enter either the rainwater system or the sewage system respectively, thus achieving separation of clean and dirty water streams.
A fire barrier can be installed in the rainwater drain to create a sealed section of the drainage channel!
1. In the event of an accident in the tank area, if the amount of leakage is too large to be contained by the initial rainwater collection tank, it will flow naturally into the accident wastewater tank through the open rainwater drains along the road. 2. The accident wastewater tank is deep enough, so natural flow is no problem at all
It flows by gravity through the water seal well to the accident pool.
The last edit to this post was made by touchskyyy on 2019-5-15 at 16:17. There are two sets of valves outside the floodwall, one connected to the rainwater system and the other to the sewage system; under normal conditions with no accidents, the rainwater valve remains open； In an emergency, close the rainwater valve and open the sewage valve. Additionally, a liquid seal device is required in all cases. Additionally, the rainwater system is equipped with switching valves for external discharge, which allow the rainwater to be directed either to the accident tank or to the external rainwater drainage network. This is my personal understanding; I hope the teachers can correct me.
A valve well is installed outside the fire dike, allowing a single pipeline to supply both the primary rainwater tank and the accident tank.