Difficulty in heating up the synthesis tower during initial startup

Steam injection is a form of throttling expansion, and the steam temperature drops after injection. The temperature of saturated steam at 3 MPa is around 230°C; combined with the heat losses in the system, the catalyst temperature rises to approximately 210°C. The CO level can be increased gradually, using the heat of reaction to raise the temperature, with reduction taking place simultaneously during production.

Superheated steam is used to increase the steam pressure

It’s explained clearly on the 2nd floor; the original poster can give it a try

What is the temperature of your desalinated water? The scheduling team can appropriately increase the temperature of the desalinated water; increasing the steam pressure is also an option. It is advisable to be cautious when carrying out reduction while production is in progress. This issue is sometimes related to the catalyst loading, and this factor depends on the temperature rise during the initial reduction stage.

The temperature of synthesis can be increased by raising the steam pressure, as well as by choosing the appropriate catalyst for the selective conversion of CO2 and CO; a higher heat release rate can also be achieved by increasing the concentration of these components

The circulation volume of the synthesis loop can also be appropriately reduced!

It is also possible to use by adding a portion to the boiler water. The key is that it will be fine as long as there is reaction heat.

It’s explained clearly on the 2nd floor; the original poster can give it a try

May I ask whether the temperature mentioned by the poster refers to the temperature of the bed layer or the exit temperature of the synthesis tower? If it is the exit temperature, it’s possible that the circulation rate is too low and thus insufficient heat can be carried away; this has happened in our company as well. Do your synthesis towers have temperature measurement points at the bed layer? Ours doesn’t; in ours, the catalyst is installed in the tube side

Generally, it’s sufficient to raise N2 to 210 degrees. If it needs to be raised to 230 degrees, firstly, it’s not possible to do so; secondly, even if it is raised to that temperature, the temperature of the syngas will change significantly

It can be driven by a syngas compressor cycle to transfer heat; it should reach 210

Could the poster please provide some information on the structure of the synthesis tower? The poster also didn’t specify whether the heating steam is saturated or superheated; some people say that increasing the pressure can solve this issue, but it’s a bit confusing. On a side note, poster, does vibration occur once the heating steam enters? Please share any experience you have in this regard.

In addition to what the people upstairs have mentioned, it’s also possible that the pressure of the steam generated by the synthesis tower isn’t properly adjusted. That’s my humble opinion

1. Slightly increase the steam temperature. 2. Reduce the amount of steam sent out from the steam drum. 3. At the beginning, the quality of the gas in the system is poor; therefore, the amount of venting should be increased to raise the proportion of effective gases in the earlier stages of the process.

Is it really necessary to raise the temperature that high? An inlet temperature of 190 is sufficient. Raising the temperature can only be adjusted by increasing the air pocket pressure. During the brief shutdown of our plant lasting over ten hours, the catalyst was not kept at a proper temperature; its inlet temperature was even below 180 degrees. The catalyst has been in use for over two years, and the H2S poisoning of the catalyst persists, remaining at around 0.1PPM

Our factory also has this issue; it’s said to be a design flaw.

Personal suggestion: 1. What is the temperature at position 210? If it’s at the inlet or outlet, then gas can already be introduced; there’s no need to raise the temperature any further. 2. If the temperature seems a bit low, consider the issue of the circulation rate – either too high or too low circulation rates can result in low temperatures. If the circulation rate is too high, too much heat is carried away, preventing the temperature from rising. If the circulation rate is too low, the heat cannot be completely removed; as a result, the temperature near the ejector is high, while the temperature at the tower outlet may not be high. 3. Earlier, a member mentioned raising the steam temperature. I personally think this will definitely be effective in raising the temperature, but under normal circumstances, the pressure and temperature of steam pipelines are designed to be fixed values, so increasing them may not be as simple as it seems. 4. Using 3MPA of steam to raise the temperature of the synthesis tower should be no problem

In our plant, the synthesis is carried out using Ruchi shell-and-tube synthesis towers. The temperature increase referred to here is the outlet temperature of the synthesis tower; this temperature also constitutes one of the conditions for gas distribution in the tower – it is lower when a new catalyst is used and higher when an old catalyst is used. It’s very simple for experienced operators: 1. Keep the level of liquid in the synthesis drum at the lower limit, and close the boiler water discharge valve. 2. The steam pressure should normally be 3.0 MPa; it should be increased to 3.5 MPa during the synthesis process. 3. The circulation rate should be moderate – neither too low nor too high. 4. Start with a high flow rate for the discharge of steam from the synthesis drum, then reduce it to a moderate level. 5. When the temperature exceeds 200 degrees, add a certain amount of reducing gas to accelerate the heating process (this applies to old catalysts). Our plant has never experienced any production disruptions due to difficulties in raising the synthesis temperature

Firstly, the system pressure can be appropriately reduced, as the large flow rate results in more heat being carried away than the heat supplied by the startup injector； Secondly, increase the drum pressure appropriately.