The alkylation reaction products are acidic
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After being pickled, alkali-washed, and washed with water, the reaction products enter the fractionation tower. At this point, their pH value is 3. The heat exchanger used for feeding the fractionation tower, as well as the air cooler at the top of the tower, suffer from severe corrosion. I would like to ask experts: what causes this phenomenon, and what is its root cause?
This is something that the industry has always been wary of and concerned about; I’ve dealt with such accidents in factories that are only slightly different from this one three times, and each time it resulted in severe financial losses! We have always been vigilant against such accidents; there are various causes for them, and in the case of your factory, it is necessary to carefully examine your operational parameters and relevant analysis indicators. However, there are several key points worth noting: 1. The pretreatment of impurities in the alkylation raw materials was not done properly, resulting in a large amount of impurities entering and causing chemical acid leakage ； 2. Physical acid runaway caused by improper operating methods ； 3. Since your company has started pickling, it’s possible that the pickling process was not carried out properly, which has resulted in acid remaining in the back area. The losses from such accidents are significant; they must be dealt with promptly, effectively, and quickly! ! ! ! ! ! Remember! Remember! If you have any questions, feel free to call at any time; we will definitely help if we can.
After the reaction products undergo acid washing, alkali washing, and water washing, there are still many dispersed water droplets and bubbles remaining in the continuous organic phase. The greater the viscosity of the organic phase, the more dispersed aqueous phase it can carry. Insufficient alkali washing leads to acid dissolution in the aqueous phase ； Excessive alkali washing; water-soluble alkali. The dispersed aqueous phase containing dissolved acids and bases is detrimental to downstream fractionation tower systems. Relatively speaking, the alkali solution causes a slower rate of corrosion on the equipment in the downstream fractionation tower system. The feed organic phase prior to entering the fractionation column must be processed through a high-efficiency liquid-liquid separator to remove as much of the dispersed aqueous phase from the organic feed as possible. This is the core of the final control technique used by the original poster to address the issue of acid in the feed stream of the fractionation tower. The less residual dispersed aqueous phase there is in the feed organic material, the fewer acid and base solutes it contains, and thus its corrosiveness to downstream equipment is **reduced**. Regarding liquid-liquid separation technology equipment, I have provided detailed explanations in many technical posts on the forum.
Regarding technical discussions on liquid-liquid coalescer separators, please refer to the following professional discussion thread posted on the Haichuan Chemical Forum: 27. Discussion on operational issues related to the toluene**oxime-water two-phase liquid-liquid separator in a caprolactam plant. Please visit http://bbs.hcbbs.com/thread-1576418-1-1.html to participate in the discussion. 40. Regarding the instability in the operation of the alcohol synthesis unit in the **device and the waste alkali liquid separator, which leads to problems in the operation of the subsequent coagulation separator, please visit http://bbs.hcbbs.com/thread-1620515-1-1.html to participate in the discussion. 66. Regarding the structural design of a new type of three-phase separator with a composite weir chamber at the top of the residue stripper and wastewater stripper, please visit http://bbs.hcbbs.com/thread-1644715-1-1.html to join the discussion. 73. For discussions on the design of a precision deep dehydration separator for the VCM liquid phase unit, please visit http://bbs.hcbbs.com/thread-1650550-1-1.html to participate in the discussion. 74. For discussions on the new composite weir-chamber structure design for three-phase separators and the retrofit design of traditional structures, please visit http://bbs.hcbbs.com/thread-1651419-1-1.html to participate. 81. Regarding the use of coalescing screens in foreign process packages for the design of oil-water coalescing separators and gas-oil-water three-phase separators, please visit http://bbs.hcbbs.com/thread-1658293-1-1.html to participate in the discussion. 84. For discussions on the use of liquid-liquid coalescing separators for efficient separation of hydrocarbons from water, alkylates from acids, light hydrocarbons from MDEA solutions, and hydrophobic phases from hydrophilic phases, please visit http://bbs.hcbbs.com/thread-1664985-1-1.html.
It seems that there is no free mineral acid along with the fractionation; the water in the filter after washing is neutral, while the water coming out of the coagulation separator is acidic. It appears that the acid is carried in the oil phase and cannot be removed by alkaline washing
Pay attention to your alkali washing temperature, alkali concentration, and circulation rate； The water washing circulation volume and discharge volume; normal water separation in the rear-stage coalescer does not result in acidity. It’s your alkaline and water washing that caused the problem.
There’s no need to call; we can just talk right here. In the absence of tigers, monkeys rule the jungle – HaiChuan is a community-oriented technical forum. No need for pretense; if you have any questions, just leave a message. These days we’re in scoring mode: answers will earn you wealth points
The OP asked about the sourness in the aftertaste; how come you’re arguing with me about this? If there are any problems, just bring them up; don’t veer off-topic. In the previous post, it was claimed that I didn’t make any modifications to the isobutane tower at all. Now you bring up Guan Guan in this context. This is a normal discussion about issues, yet you bring up the Haichuan Forum as well. It’s really frustrating – why do you argue with others in a group chat and then leave the group? Bro, I don’t want to argue with you; just do your own job. I don’t want to waste time either, so let’s stop here. I also reflected on why I was fired by the company after just two days. Without further ado, Haichuan isn’t a place for arguments; if you really have any grievances, let’s resolve them privately.
Is there a recycling system for your pickling process? If available, remove the circulation from the pickling tower and let the product pass through a static acid bath.