Several issues in the design for chlorine gas absorption in accidents
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There are currently four liquid chlorine storage tanks, enclosed in glass fiber sheet enclosures with dimensions of 20m*15m*8m. Two towers connected in series need to be designed to absorb chlorine gas in the event of an accident. I have a few questions for everyone: 1. How is the air exchange rate calculated in case of a leak? Is it based on the ventilation standards, which require 12 air changes per hour in the room? 2. Should the fan be placed before or after the tower? What is the reason? I’ve seen examples online where the air that has been absorbed by the absorption tower is circulated back into the liquid chlorine room; I think this is a good approach. If the absorption isn’t sufficient, it’s possible to carry out additional absorption cycles, but are there any disadvantages to this? 3. How is the amount of chlorine leaked calculated, given that there are many types of leaks? What is the maximum amount that can be leaked? How should the size of the alkali circulation tank be determined? Should the base be prepared all at once, or can it be supplied from outside? 4. According to the literature, the alkali used for absorption is generally around 16%. Why isn’t a more concentrated alkali used? Is it due to concerns regarding the insulation and heating of the alkali tank, or is it fear that a high negative pressure generated during the absorption process might damage the equipment? 5. How many air inlets are needed to extract chlorine gas? Considering the randomness of leakage points, is it better to install more of them? If any of the seniors have worked on similar projects, it would be great to be able to draw on their experience. Thank you!
@*lihuagong @Thankfully you’re here @Fish_in_the_desert @Sammy_Wang Great guys, please help solve this problem!
This post was last edited by *lihuagong on 2016-6-3 14:52. I can’t say anything else as I’ve never had contact with liquid chlorine. However, we also have devices for removing HCl and Cl2 from exhaust gases, which can be used as a reference: 1) Two towers in series, with one tower under negative pressure and the fan located between Tower 1 and Tower 2; the other tower is under positive pressure. 2) Tower 1 uses water circulation to absorb HCl, while Tower 2 uses dilute alkali to neutralize and absorb Cl2 and HCl; the exhaust gas at the top of these towers is released directly into the atmosphere. 3) The alkali solution used is 10%; the concentrated alkali we obtained from other plant sites is 32%, which is then diluted to 10% for use. I think there might be two reasons for this: A: Concentrated alkali pipelines need to be kept from crystallizing, which requires steam heating and insulation; this is complicated to manage and comes at a high cost. B: When concentrated alkali is absorbed directly, the reaction heat is high, resulting in unstable control within the tower. 4) According to conventional design, shouldn’t the absorption tower be designed based on the maximum discharge volume? In the case of cyclic absorption, it might be considered to reduce the size of the absorption tower, also as a way to cut costs. No experience. I’m actually quite curious – what is the size of your liquid chlorine storage tank? Why not control the liquid chlorine tank, but instead build a sealed box outside the tank? Aren’t you worried that the box might leak? Logically, you can simply control the liquid chlorine storage tank; a safety valve is installed on the top of the tank, and the pipeline from this safety valve leads to the alkali solution absorption tower. In this way, the amount of fluid that can be released can be determined based on the discharge capacity of the safety valve. @At the foot of Hengshan Slope
Thank you very much for your explanation. Nowadays, liquid chlorine storage tanks are required to be sealed in order to prevent the leakage and spread of chlorine gas; that’s why this emergency absorption system is needed. It’s not related to the release function of safety valves, but rather addresses situations such as leaks caused by poor sealing at flanges or corrosion of valves. Such leaks are difficult to contain, so the tanks need to be enclosed within sealed rooms
I see the original poster posted this a year ago; they should have started doing it by now, right? We are also facing this issue; we would appreciate your guidance.
I’m facing the same problem and would like to ask you for advice. Would you like to leave a way to contact you? It’s best by phone
On our end, the fans are installed in front of the tower, and several axial flow fan inlets need to be set up around the warehouse; several mobile absorption hoods can also be placed in the warehouse to facilitate the absorption of minor leaks. The alkali solution is prepared at around 16-20%, mainly to consider the absorption efficiency. Too low a concentration results in poor absorption, while a high concentration makes it difficult to determine the endpoint of the absorption process. Moreover, the formation of sodium hypochlorite by absorbing chlorine gas leads to its easy decomposition.
In my humble opinion, our factory has a methanethiol storage tank that is highly toxic. Our protection measures include various anti-differential pressure systems, safety valves, high-pressure interlocks, high-level interlocks, as well as cathodic protection to prevent the tank from corroding and becoming thinner. The tank is also enclosed in a concrete structure, so that in the event of a leak, the substance will not spread over a large area. In addition, there are spraying systems, along with temporary connections that allow for the transfer of methanethiol. First and foremost, it comes down to investment in intrinsic safety; as for measures to mitigate severe consequences, there are only a few options available.