A problem that occurs when stopping the hydrochloric acid process… Experts, please help!

Substitution isn’t the key; how to deal with chlorine? Combined, chlorine gas cannot escape.

Mm-hm. What was said upstairs is absolutely correct – this is the key to the replacement process! The current approach is to connect the N2 fitting to the discharge port of the chlorine flame arrester; first, the inlet of the chlorine flame arrester is isolated using a blind flange, and then N2 is introduced so that the chlorine gas can be drawn through the synthesis furnace and absorbed in the acidic water tank ； Because there won’t be much chlorine in this portion, it won’t cause significant pollution either. After 5 minutes of displacement, stop the supply of N2, isolate the outlet of the chlorine flame arrester using a blind flange, then remove the blind flange at the inlet, and subsequently resume the supply of N2 ； Send the N2 back along the delivery pipeline to the chlorine distribution station, from where it is sent to waste gas treatment. Could anyone give some advice? This post was last edited by limingshuguang on 2007-11-30 09:05.]

The blind flange on the main chlorine pipeline in the hydrochloric acid production process was removed, and back-pumping was carried out using the chlorine compressor from the chlorine treatment process; the chlorine from the hydrochloric acid production process was then drawn through the chlorine compressor into the external pipe to produce substandard sodium hypochlorite!

A vacuum tube connects to the accident chlorine treatment unit on the chlorine buffer tank. Close the buffer tank feed valve. After evacuating to vacuum, install the blind flange. Prolonged parking – purge with nitrogen and then maintain pressure with nitrogen. Parking for maintenance – open the furnace door and open the chlorine valve on the pipeline. Start the blade after air replacement is approved. Pay attention to the replacement of dead corners in the pipelines. The pipeline replacement sequence is from far to near the chlorine buffer tank. Hydrochloric acid is easy to handle in a chlorine gas system, and it doesn’t take long. Last edited by Royal Jelly on 2007-11-30 20:51.]

The feasibility of this isn’t high, is it? Hydrochloric acid is already produced by using liquefied exhaust gas, and chlorination treatment requires that gas to be liquefied first. Moreover, there shouldn’t be a need for such large amounts of chlorine, right? I’m not sure what is used to produce sodium hypochlorite waste as you mentioned; if it’s caustic soda, then it’s something that results in equal losses as gains. There’s basically no economic benefit… There’s a big difference between theory and practice... :funk:

After the replacement is completed, there is no more chlorine present; the chlorine pipeline is filled with N2. What’s the point of creating a negative pressure at this point? Are you worried that the chlorine hasn’t been completely replaced, or are you concerned that the valves preventing chlorine from entering aren’t sealed properly? Even if chlorine is drawn out, wouldn’t that still contaminate the environment? Moreover, creating a negative pressure doesn’t it increase the risk of chlorine entering through the main chlorine pipeline due to low pressure?

This is the simplest way: just do the same as is done to introduce chlorine into the hydrochloric acid synthesis furnace – that is, pump air back in to evacuate it! Generally, first ensure that the interior of the hydrochloric acid synthesis furnace is properly evacuated (by closing off the valves for chlorine and hydrogen supply to the furnace), then use a chlorine distribution unit to pump air out of the chlorine pipelines supplying the furnace. Once a negative pressure is achieved, open the valve for chlorine supply to the furnace; subsequently, replace the chlorine with air or nitrogen. It can be done in very little time!! :lol :lol

Well, I basically agree. My personal opinion is that for short-term parking, there’s no need to replace the chlorine gas; it’s better not to evacuate the air but instead use N2 to displace it. This way, even in case of a leak, the risk is reduced due to the lower concentration, and there’s no need to worry about how to install blind flanges when the pressure inside the pipes is low. The same principle applies when performing maintenance while the system is parked – N2 should be used to displace the gas so that it can be sent to waste gas treatment systems. There’s no need to simply evacuate the air for displacement. As for dead corners in the pipelines, they should also be taken into account during design, so that they can be displaced as well.

Let me ask a few questions: 1. How is negative pressure created in the chlorine extraction pipeline? Is there any power equipment at the distribution station? 2. How can we ensure that vacuum is achieved during the extraction process? Will continuously creating negative pressure without stopping have an impact on the system’s pipelines? 3. Assuming that the synthesis furnace has been properly purged, isn’t it a waste of effort to use it again at this point?

Connect the raw chlorine and waste chlorine supply stations for liquid chlorine, then open all the valves from hydrochloric acid to waste gas one after another and pump for a few hours. After that, open the furnace door and continue pumping for some more time. Be careful to monitor the furnace pressure before opening the door – this ensures that no chlorine gas is released into the atmosphere. :lol Of course, make sure to close all the valves related to the hydrochloric acid completely during the pumping process. This post was last edited by limingshuguang on 2007-12-17 at 10:15