No water can be drained from the deisobutane overhead reflux tank in the alkylation unit, but there is a lot of water at the inlet of the circulation pump
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As stated in the title, the water separated from isobutane in the reflux tank (located on the platform, about 15 meters above the ground) cannot be removed effectively; only a small amount of water comes out. During an 8-hour shift, only 500–1000 ml of water is discharged. However, at the inlet of the reflux pump (which is on the ground level) and at the lowest point of the pump itself, water must be drained during each shift, with a volume of around 7–8 liters. Additionally, the pH value of the water is between 4 and 5. The amount of water used for alkaline cleaning has already been increased to its maximum, and the same holds true for the amount of water used for washing. How to adjust? Please give me some advice!
1. Equipment issues: There may be problems with the design, manufacturing, or installation of the dehydration pack itself, as a result of which the free water present in isobutane cannot enter the dehydration pack. This possibility is low; it is recommended to consult the drawings to investigate the issue. 2. Process-related reasons: In my opinion, the reasons in this area include the following: a. The washing tanks in the alkylation purification system are not operating properly; there are issues with the coalescers inside the equipment or with the level control of the liquid in the tanks, which results in the presence of free water in the subsequent processes. It is recommended to lower the liquid level in the washing tanks and to inspect the coalescers during maintenance ； b. Check whether the circulating water pressure is higher than the pressure in the reflux line for isobutane removal; it is essential to verify whether there might be a leak in the water cooler, as the acidic nature of the water is related to this issue ； c. Operational conditions during the process may exceed the design parameters; for example, an excessive amount of isobutane in circulation can prevent water from settling in time, causing it to be drawn in at the pump inlet. However, due to the higher pressure difference at the pump inlet, it is possible to settle this water more easily ； Secondly, it is also necessary to confirm whether the load of the cyclobutane tower deviates from the design value. Personal opinion, for reference only
Thank you. The pH value of the wash tank is around 9; why is it lower at the top of the isobutane removal tower and in the circulation pump? After being pumped out, isobutane is divided into two streams: one stream goes to the reflux column, while the other stream passes through a water cooler before entering the reactor as circulating isobutane. It seems unlikely that it’s a water cooler issue, so we have to wait until maintenance is done. Also, expert upstairs, the isobutane inlet line for my tower top reflux drum is connected at the bottom of the drum – could this lead to corrosion?
Increase the pressure in the washing tank to 0.95 MPA; the liquid level on site is 75–80 cm. I’m not sure what the purity of isobutane is where you are Perhaps the amount of cyclic isobutane is too large, leaving no time for it to settle.
Is the pH 4-5? Strong acid? Is the alkali cleaning not effective?