Catalyst heating issue in the synthesis tower

As long as the even heating of the catalyst can be ensured, that’s sufficient.

Introducing syngas before the synthetic catalyst reaches its active temperature range can lead to wax formation, which in turn affects the catalyst’s service life as well as the quality of crude methanol

It’s difficult to control the rate of temperature increase: 1. The internal cold tubes are prone to damage； 2. Sudden temperature increases can easily cause the catalyst to become pulverized

Could LZ explain the specific steps? I’m very interested in your method of introducing fresh air at 120 degrees.

At 120 degrees, the reduction of copper oxide has not yet been completed; introducing fresh gas at this point will affect the formation of the active components, as well as the strength. It’s best not to do this; a catalyst costs quite a lot of money!

I have driven in this way several times, and there has been no overheating of the catalyst

Thus, the impact of driving on the catalyst’s lifespan and strength can be determined by the frequency at which the catalyst’s temperature is increased over time; this shows whether its lifespan has been reduced. The later in the process, the more frequently the temperature needs to be increased

No, this is really novel. See if I’m right: ① handshake – you mean that currently your reactor’s temperature can only reach around 120°C; normally, the temperature needs to rise to around 170°C before the process is complete. You started the reduction process before the entire heating phase was finished... (As mentioned by the user on floor 6, I think the catalyst wasn’t deactivated during operation.) ② handshake – if your catalyst has already been reduced, you mean that syngas should be introduced at 120°C. I think that’s what you mean; it seems to you that the synthesis reaction can occur at 120°C. If that happens, could you check the composition of your crude methanol and determine what the alcohol content is? This practice is explicitly prohibited in the operating procedures. The low-pressure process already suffers from severe wax formation, and yet this condition is still applied... I’m glad that there was no overheating during operation. You shouldn’t be thanking yourself; it should be the steam drum instead. It would be better if the synthesis tower had an insulating layer. What was the highest temperature in your synthesis tower at the beginning? If it was also 120°C, then your catalyst is really on its way to being ruined. Nonsense. I’ve only started working recently~~~

In my opinion, the temperature measurement point should be at the outlet of the synthesis tower, as local overheating inside the tower cannot be detected in a timely manner.

I wonder if the steam you divert is being directed to the steam drum!

Could you explain how steam can be reversed? I’ve been learning about it

The design of the steam ejector is capable of meeting the temperature rise requirements; check your temperature rise process, and perform chemical cleaning on the water side if necessary. Also, ensure proper management of the boiler feedwater.

The minimum level of the drum liquid level is maintained, and the pressure of the external steam supply is raised to 1.0 MPa; steam is then directed back from the steam outlet pipe of the drum to heat the catalyst. The catalyst becomes active when its temperature reaches 175 degrees Celsius. The drum liquid level is controlled through the waste discharge pipeline of the synthesis tower.

Then your tower type should be the Ruchi type. For this type of tower, we apply heating at the bottom of the tower during temperature elevation, and then steam is returned from the drum outlet to increase the drum pressure; the drum liquid level is controlled by draining water from the synthesis tower. A problem of this kind can occur when the liquid level in the synthesis tower is relatively low. Regarding the poster’s issue, at that time the steam temperature was low and the rate of temperature increase was slow; we tried such measures as well, but the temperature needed to reach above 190 degrees.

Our plant’s synthesis tower drum is designed with a direct steam pressurization pipeline, using medium-pressure steam at 4.0 MPA, eliminating the need to pump steam back from the steam outlet. When we use the ejector to raise the temperature, we first open this steam valve to increase the pressure in the drum to 1.5 MPa (2.7 MPa for normal operation), and then use the ejector to raise the temperature. As the temperature rises, the pressure is gradually increased to normal levels using the heat provided by the ejector, thereby ensuring that the temperature reaches the required level.

Steam from the steam pipeline network is used to push back pressure from the drum into the shell layer of the synthesis tower; this is a necessary measure since there isn’t enough medium-pressure steam available for the ejector, which results in a prolonged heating time. However, this method increases the steam flow rate and significantly speeds up the heating process, so I think it should work. However, it is important to note that 1) the nitrogen in the tube bank of the synthesis tower must be circulated, and the exit temperature of the synthesis tower should be monitored at all times to prevent overheating. 2. Introduce fresh gas only when the temperature exceeds 190 degrees Celsius; otherwise, paraffin will be formed. 3. After introducing fresh air, it is necessary to establish the liquid level. Avoid a dry drum in the steam drum.

1. We just used the vehicle for driving today; it was difficult to operate, but by applying some of my experience from ammonia plants, I was able to succeed. 2. When raising the temperature, special attention must be paid to adjusting the space velocity and the amount of steam used; too high a space velocity can cause the temperature to drop, and it is also difficult to maintain stable pressure. 3. Raise the temperature to 180 degrees and increase the air supply to speed up heating, thereby preventing the formation of paraffin. 4. It is recommended not to use it unless absolutely necessary!