Soft water cooling for HCL two-in-one graphite synthesis furnace
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Since our company’s HCL two-in-one graphite synthesis furnace uses circulating water, scaling has caused severe damage to the furnace; therefore, we now intend to use soft water for cooling. I would like to ask for a detailed plan; for example, how is the circulating water volume calculated? Regarding how to achieve a closed-loop system, the main difficulty I see is how to cool the soft water – it needs to be sent to the cooling tower, and too much soft water is lost; only 15 units of energy are utilized in this process. If your response is good, I will evaluate your other posts as well. Thanks :)
One approach is to use a lithium bromide heat pump unit with soft water from the synthesis furnace, without requiring a cooling tower to cool the soft water. One method is to use steam condensate as make-up water, with the soft water being cooled by a cooling tower; another method is to use soft water as make-up water, again with the soft water needing to be cooled by a cooling tower. Among them, the method of using the soft water from the synthesis furnace along with a lithium bromide heat exchanger unit is the most reasonable.
Our freezing system does not use lithium bromide units. It uses the old-style ammonia type; soft water can be that from the old power system, and steam condensate is not required. Are you referring to a closed-type cooling tower?
Soft water can be cooled using a spiral plate heat exchanger, and the cooling water system of the synthesis furnace operates in a closed loop. Ordinary cooling water exchanges heat indirectly with the cooled soft water from the synthesis furnace through a spiral plate heat exchanger; as a result, the amount of soft water that evaporates is minimal, and the investment required is low, making it easy to implement. This post was last edited by Wang Genrong on 2009-3-20 at 15:51.]
Could you explain it in more detail? I’m a bit confused – when cooling soft water with a spiral plate heat exchanger, is industrial circulating water used? Since our circulating water is quite dirty, I think spiral plate heat exchangers are prone to clogging. What does that plate heat exchanger mean? Isn’t soft water cooled by the spiral plate heat exchanger? Also, doesn’t the plate heat exchanger have a relatively high resistance? Due to the large volume of water, it may be difficult because of the high resistance. Please give me some advice. This post was last edited by limingshuguang on 2009-3-22 20:33.]
The cause of scaling is a problem with the scale inhibitor; the issue can be traced back to the scale inhibitor itself. Would it be putting the cart before the horse to switch to soft water for cooling?
1. A closed-loop circulation of soft water can be achieved by adding a soft water circulation tank, a pump, and a plate heat exchanger. 2. The circulation volume of soft water requires you to calculate the heat based on the production capacity of the synthesis furnace. The general principle is that if soft water is cooled using circulating water, the flow rate required should be higher than that used currently for such cooling. If you have extra 10-degree water or 5-degree water, you could consider using it, but it’s not cost-effective; the circulation volume will be much lower. 3. Ammonia refrigeration is an obsolete technology; if your company has plans for technical upgrades, lithium bromide refrigeration could be considered as an alternative. As the friend above mentioned, the hot water produced by the synthesis furnace is sent to the lithium bromide unit. This post was last edited by limingshuguang on 2009-3-22 20:36.]
Reply to the original poster: There is some validity to the concern that spiral plate heat exchangers are prone to clogging, but the flow rate of the cooling water in such exchangers can be increased, and scaling usually does not occur at high flow rates. If my estimate is correct, your company has been using graphite synthesis furnaces since 1993, right? Was your PVC design based on a capacity of 30,000 tons? Your exhaust gas absorbers have been performing well, with no serious scaling or blockages occurring. This shows that you can also use graphite heat exchangers in place of the spiral plate heat exchangers I mentioned earlier, although the investment required is higher. This post was last edited by Wang Genrong on 2009-3-20 at 16:32.]
We use circulating water for cooling at the moment, and this circulating water is quite dirty; for example, the PVC centrifuge mother liquor contains waste PVC, and simply adding a polymerization inhibitor isn’t enough to solve this problem. Besides, I think using soft water is also the most fundamental way to address the issue of scaling, right? This post was last edited by limingshuguang on 2009-3-22 20:37.]
It’s pretty much in line with my thoughts; I still plan to use a spiral plate heat exchanger – one with a detachable end, where the detachable part will be used for the circulating water, while it won’t need to be detached for the soft water. As for replacing it with a lithium bromide unit, well, currently, due to the economic crisis, it’s difficult for companies to survive; there’s no money for investment, and besides, I don’t have the authority to make such a decision.
Thank you. I’m not very clear about the use of graphite synthesis furnaces in 1993; I’m a newcomer. I heard that the PVC plant was built around 2003, with an initial capacity of 30,000 tons, and that seems to be true. Which exhaust gas absorber are you referring to? I’m considering using a graphite heat exchanger.
Reply to the original poster: The exhaust gas absorber refers to the HCl absorber located after the VCM scrubber tower; it is the one installed on the side opposite the concrete road next to the cooling tower. In fact, the degree of scaling in the absorbers used in your hydrochloric acid production section is not as severe as the scaling problem in the synthesis furnace. This post was last edited by Wang Genrong on 2009-3-20 17:28]