Reasons for the pressure difference in the synthesis tower!

Gas composition, gas volume, instrument errors, blockages in equipment pipelines, and so on could all be the causes.

It is suspected that there is a problem with the instruments. For a synthesis tower that has just started operating, there should be no issues with the gas flow or the equipment, as the preliminary production preparation stages involved water testing and purging, so the pipes should not be blocked. Another possibility is that there is a problem with the catalyst reduction process in your facility. It is recommended that you open it and check; please calibrate the instrument

Could you please share your scale and the specific figures from actual production? What is the difference from your design data? Since there are differences between the reduction process and actual production, different pressure differences can also be understood. Please also explain your reduction method – specifically, whether it is high-hydrogen or low-hydrogen – and whether anything special happens during the process At the same time, I think there shouldn’t be any problems when starting catalyst production; maybe it’s my judgment that’s flawed!

There are two main reasons for high pressure differences in the synthesis tower: one is an increase in the inlet pressure. When synthesizing methanol, there is a certain equilibrium pressure for the reaction; under normal operating conditions, this pressure remains stable. If an increase in the inlet pressure of the synthesis tower is observed, it may be due to the following reasons: ① The reaction temperature of the catalyst decreases, resulting in a poorer quality of the synthesis reaction, or even its deterioration. At the same time, fresh gas continues to flow into the tower, causing the system pressure to rise, sometimes even to excessive levels. Solution: Identify the cause of the temperature drop and take proactive measures to address it, such as shutting down auxiliary lines, cooling shock lines, or reducing the circulation volume. If the system pressure exceeds the specified limit, the amount can be appropriately reduced or vented ； ②An increase in the methane content in the recycle gas leads to a decrease in the partial pressures of hydrogen, carbon monoxide, and carbon dioxide, which affects the methanol synthesis reaction; this is also one of the reasons for the rise in the pressure at the inlet of the synthesis tower. Solution: Increase the amount of gas released at the tower outlet appropriately or reduce the methane content in the fresh gas ； ③A sudden decrease or interruption in the circulation gas flow can also cause an increase in the pressure at the inlet of the synthesis tower. Solution: Identify the cause of the sudden decrease or interruption in the circulating air volume; the compressor shutdown is mainly caused by electrical faults, instrument interlocks, and equipment defects ； ④The poor water cooling effect of the syngas leads to poor synthesis reactions, which in turn causes an increase in the pressure at the inlet of the synthesis tower. Solution: Increase the cooling water flow rate of the water cooler; in case of a water supply interruption, shut down the machine ； ⑤Other factors, such as adding or reversing compressors to increase the amount of fresh gas without notifying the synthesis unit in a timely manner, can also lead to an increase in the inlet pressure of the synthesis tower. Second is the drop in inlet pressure. When the methanol synthesis process approaches equilibrium, the system pressure remains stable within a certain range. If a sudden or gradual decrease in the inlet pressure of the synthesis tower is observed, it should be taken seriously and immediate inspection should be carried out. The common causes include: ① A decrease in the amount of fresh gas can lead to a drop in the inlet pressure of the synthesis tower, with the main reason being a compressor failure that causes it to shut down. Solution: Quickly mobilize resources to start the backup compressor and restore gas supply as soon as possible. Before resuming gas supply, reduce the circulation rate of the synthesis tower accordingly and adjust the flow rates in the main and auxiliary lines to stabilize the reaction temperature in the synthesis tower ； ②Loss of control over the liquid level in the crude methanol separator, which leads to gas leakage, can also cause a drop in the pressure at the inlet of the synthesis tower. Solution: Reduce or temporarily close the drain valve of the separator to restore its normal liquid level ； ③Leaks caused by damage to the equipment and pipelines in the compression and synthesis sections can also lead to a decrease in the inlet pressure of the synthesis tower. Solution: Organize maintenance personnel to carry out emergency repairs ； ④A slow decrease in the inlet pressure of the synthesis tower should also be taken seriously; it is necessary to check whether there are any faults with the compressors in operation, whether there are leaks in the system, and to verify whether the pressure gauges are functioning properly. This is analyzed through the reaction of the inlet pressure difference; everyone can discuss it in depth. This post was last edited by kaisl1314 on 2008-2-29 09:36.]

1. Check whether the pressure difference gauge is functioning properly； 2. Has the circulation volume increased? ； 3. Is the rate of pressure and temperature increase too fast, resulting in catalyst pulverization, or is it due to insufficient catalyst strength?

Looking forward to the owner’s final result; I hope they will have the time to tell us what the ultimate truth is!

Reason • The amount of fresh gas entering the tower is too large. •The CO content entering the tower is high. •The switches for the main and auxiliary lines of the synthesis tower are too small. •The circulation volume is too high. •Catalyst crushing and clogging equipment. •Water-cooled exhaust pipes, alcohol deposition blockage

The original poster’s question is rather vague; the points mentioned regarding Building 4# are quite professional, and it is necessary for the poster to provide some basic data parameters of the equipment in order to facilitate analysis. In general terms, the analysis of Building 5 is quite comprehensive, so no further details are needed. Let me share an example from our company where a synthesis tower, after being restored, did not operate properly. The tower had a production capacity of 50,000 tons per year; its internal structure consisted of a cross-flow heat exchange system designed by Nanhua Design Institute. The reduction process was carried out first at low hydrogen levels and then at high hydrogen levels. After operating at light load for 24 hours, the tower was supposed to start operating normally, but it was not possible to use its full capacity. The problem was that the temperature difference between the catalysts in the upper and lower sections was 100 degrees (the normal range being 10–20 degrees). After methane reduction, the temperature in one section became too high, while the temperature in the other section was even lower. Increasing the circulation rate only made the situation worse. After managing to keep the tower running for about a month, it was shut down and its internal components were taken out for inspection. It turned out that the components had just been repaired and put back into use, but there were foreign objects remaining in the main inlet pipe of the upper section, which caused uneven distribution of gas flow and led to large pressure and temperature differences. This incident took place in 1994, and the tower has now been taken out of service. The above examples are provided for reference on the first floor!