Can the separation tank before entering the main scrubber tower in the methanol washing process be eliminated?

In my opinion, this separation tank is used solely for gas-liquid separation; it separates the mixture of methanol and water that is sprayed in earlier stages from the process gas, sending it to a methanol-water separation tower for recovery. On the other hand, this helps to reduce the amount of water in the process gas that enters the circulating methanol stream； 1. The Lurgi process does not lack such a separation tank; it is simply placed at the bottom of one of the towers, in what is known as the pre-washing section. Its function is similar to that of the separation tank in the Linde process ； 2. It is primarily intended to prevent water from entering the circulating methanol system, which could lead to an excessive water content in the circulating methanol and thus affect the efficiency of methanol washing; it also allows for the recovery of the methanol that was sprayed earlier ； 3. I think it’s not feasible; this will increase the water content in the recycled methanol, which not only affects the cleaning efficiency but also increases the load on the methanol-water separation tower. Especially during startup, the water content in the recycled methanol can become very high

1. Do you mean that this separated water content affects the absorption of H2S? This view seems a bit far-fetched. 2. After being incorporated into the bottom of the main washing tower, this methanol stream is primarily subjected to flashing; it is not washed (the liquid phase exiting from the bottom of the tower contains a relatively high level of H2S). The methanol that is actually washed comes from the stream taken from the decarburization section. 3. From the perspective of the material balance of the entire system, moisture is only introduced from the process gas. If this stream is incorporated into the outlet pipe at the bottom of the tower, then the amount of moisture is the same as that discharged from the methanol-water separation tower; so how can this increase the load on the methanol-water separation tower? Feel free to give more guidance

Cancellation is not feasible for the following reasons: an increase in the methanol-water content in the system has a significant impact on the system’s ability to absorb methanol, especially when the water content exceeds 1%. The first manifestation is an increase in cardiac output. It’s also not practical to add it to the liquid-phase outlet pipeline at the bottom of the main washing tower; I’ll give you a simple and straightforward example so you’ll understand. Is it better to perform distillation by putting one cubic meter of water into dozens of cubic meters of methanol, or by putting one cubic meter of water into hundreds of cubic meters of methanol? Which one is higher for operating costs? To maintain a constant water content in the system, the water separation tower must remove an equal amount of water to that which is introduced with the process gas. By connecting the separation tank to the liquid phase outlet pipeline at the bottom of the main washing tower, it’s as if you’re adding one cubic meter of water to several hundred cubic meters of methanol; whereas spraying methanol for separation is like adding one cubic meter of water to dozens of cubic meters of methanol. By the way, Ruchi does have a separation tank; it mixes the methanol used for spraying with a very small portion of the methanol used for washing ammonia and cyanides from the bottom of the tower.

Everything I wanted to say has already been said by jjlhero, so let me raise a few questions! This post was last edited by z880347730 on 2009-2-10 19:12]

How will adding the methanol-water mixture from the separation tank to the water separation tower affect the operation? ? ? ? The main purpose of the methanol-water separation tower is to separate this methanol. It’s just that a exhaust gas scrubber is now included in the new process, so the water separation tower has to handle this additional amount of water!

Ugh, adding it before the main washing tower is the best option, as it helps to maintain the proper water level in the system. What’s the point of adding it later on?

The lower part of the water separation tower is almost entirely filled with water~~ The water that is separated out is mainly used as washing water in the exhaust gas washing tower~~ Some of the wastewater is also discharged~~

Basically, that’s all there is to say. One more thing is that this liquid has a high water content, and its presence in the methanol-rich stream at the exit of the absorption tower will accelerate the corrosion of the subsequent equipment.

Let’s learn it:) :) :)

Is the water content very high? As far as I know, the water content isn’t that high! If the water content is high, how is this methanol fed into the thermal regeneration tower in the Ruchi process? How is this to be explained then? The above are purely personal opinions; please feel free to point out any mistakes!

Corrosion intensifies when the water content in the system’s methanol exceeds 1%! Here, 40 KMOL of water is separated per hour; the total amount of methanol in the system should be around 30,000. Otherwise, the water content will increase to 1% within a day. Could you tell me about the processing capacity and steam consumption of the Lurgi water separation tower? Perhaps Lurgi uses a higher amount of steam to separate the water! This post was last edited by z880347730 on 2009-3-2 23:20]

The amount of water in this portion is actually not very large, but what is the ratio between the water separated by the separation tank and the amount of water that enters the absorption tower? Calculated based on the design (Linde process): the temperature of the gas entering the low-temperature methanol wash unit is 40 degrees, corresponding to a saturated vapor pressure of water of 0.00685; the temperature in the separation tank is -12.7 degrees, with a corresponding saturated vapor pressure of water of 0.00018 Mpa. Only 1/38th of water is introduced into the absorption tower, and the solubility of methanol in water has not been taken into account.

Processes that offer more advantages than disadvantages should of course be adopted; chemical processing technologies are becoming more mature step by step, and we should carry forward the good aspects of them. This separation tank cannot be ignored; it plays a crucial role at critical moments by removing a large amount of the moisture contained in the process gas generated through gasification. Reduce corrosion of the equipment.

It’s impossible to remove it; everyone thought it was just a jar, but in reality its internal structure is quite complex. During this year’s major overhaul, the company decided to replace it with a new one; I got to see its internal structure. The gas inlet inside is equipped with folded steel plates, whose function is to create vortices. At the outlet, there is a layer of gauze containing oil-like substances, which is secured with steel plates; this is done to remove moisture from the transformed gas and prevent an excessive water content in the circulating methanol, which could lead to slight excess levels.

Our factory uses Linde technology; there is a separation tank right before the methanol scrubber, and it plays a very important role. The main purpose is to reduce the moisture content in the feed gas, to dry it, and to prevent the moisture present in the feed gas from causing blockages in pipes and equipment due to freezing upon cooling.

What’s the point of discussing this anymore? Which low-temperature methanol washing process doesn’t have a separation tank? Tell us, and let’s see how it’s handled – that’s what’s really important.

If separation is not carried out, it will increase the amount of water introduced into the main washing tower, affecting the absorption of sulfur compounds

I completely agree with you! In reality, Lind’s process is still better! Lower moisture control! In single-system operation, the system moisture level is controlled to 0.07%! The dual-system rate is only 0.25%!

I completely agree with you! In reality, Lind’s process is still better! Lower moisture control! In single-system operation, the system moisture level is controlled to 0.07%! The dual-system rate is only 0.25%!