What is the boiling point of deoxygenated water? What is the temperature of syngas?

Regarding the second question, I’d like to share some personal views. From a thermodynamic perspective, both ammonia synthesis and methanol synthesis are exothermic reactions. The catalysts used in these synthesis processes impose certain limits on temperature. If an adiabatic reactor is used for the synthesis, two possible outcomes can occur: ① The temperature exceeds the acceptable range when the desired conversion rate is achieved； ② If the temperature is kept within the permitted range, the conversion rate is limited, thereby reducing the production capacity of the synthesis tower. If a tubular reactor with external medium heat exchange using Lurgi’s gas heat exchange and water cooling methods is employed, adjusting the process conditions appropriately should ensure that there are no problems even if the temperature of the syngas is slightly higher

Could the person on the second floor please explain in detail what the ideal temperature for syngas is? Additionally, if the temperature becomes too high, what measures are taken in the subsequent systems to deal with this issue? We use a gasification furnace with a pressure of 3.0 MPA; the pressure at the output stage is 2.7 MPA, and the temperature is 203 degrees. We also have a 4-nozzle gasification unit with a pressure of 4.0 MPA and a temperature of 240 degrees. So, how should such high temperatures be handled? This post was last edited by Langtaosha on 2008-3-14 at 11:12

The issue you raised actually relates to the water-to-gas ratio in the crude syngas production stage. In coal water slurry gasification, the water-to-gas ratio at the carbon washing tower is typically around 1.4. The saturated vapor pressure of water corresponding to the temperature conditions at the Lunan plant is 1.65 MPaA. If the syngas pressure is 2.7 MPaG (i.e., 2.8 MPaA), then the water-to-gas ratio is 1.65 / (2.8 – 1.65) = 1.43 ； The synthesis gas pressure at the carbon scrubber corresponding to 4.0 MPa of gasification is 3.8 MPaG, and the corresponding temperature should be around 220 degrees (240 degrees is not possible) ； The syngas pressure corresponding to 6.5 MPa of gasification is 6.3 MPaG, with a temperature of around 245 degrees. This water-to-gas ratio is determined by the thermal balance of the gasification process itself; there is basically no significant difference in the corresponding water-to-gas ratio at different gasification pressure levels ； Theoretically, at the same vaporization pressure, the lower the amount of quench water and the graywater circulation volume, the higher the temperature of the syngas, and consequently the higher the water-to-gas ratio. This allows for a reduction in the amount of catalyst required for the downstream shift reactions. Additionally, an increase in the amount of medium- and low-pressure steam generated during gas cooling leads to an improvement in the overall thermal efficiency of the system ； It has no direct connection with the downstream synthesis stage, as the syngas needs to be purified at low temperatures before entering the synthesis process, and it must be cooled before purification.

Thank you so much, bone... This post was last edited by Langtaosha on 2008-3-14 at 11:13.]

Hehe, the answer from the 4th floor was very professional; I only discussed it briefly from a thermodynamic perspective, as I haven’t actually done any work related to this topic

Our furnace operates at 6.5 MPA, but we usually use 5.8 MPA, with the syngas outlet temperature around 220°C! As for the water vapor ratio, it is usually around 1.1; this is also just an approximate value. If the temperature is high, I generally assume that liquid is present! It will be easier to handle this way!

The high temperature of syngas – what harm does it cause to the subsequent systems (ammonia synthesis, methanol production)? I’ll answer that question! After the general process of gasification is completed, the next step is conversion. High temperatures mainly affect this conversion process; for example, increasing the heat load on the converter reactor may make it difficult to control the pressure in that reactor, and there may not be enough time to add water… It also has an impact on the converter furnace itself – an increase in the dew point temperature of the feed to the converter furnace can lead to a rise in the conversion temperature. It becomes much smaller after purification

I wonder what you produce?

It doesn’t matter what the boiling point of deoxygenated water is; the key is to ensure that oxygen can be removed from the water at the specified pressure. For example, the boiling point of water at normal pressure is 100 degrees; therefore, adding heat up to 100 degrees is sufficient. If you try to raise the temperature further, there is no change in the deoxygenation effect, it’s just a waste of effort, and it can also lead to cavitation in the pump. The temperature of the process gas is primarily determined by the water vapor ratio required in subsequent conversion steps; a higher temperature of the process gas leads to a higher water vapor ratio, which can easily cause water carryover incidents. If the temperature is low, there will be a insufficient water vapor ratio, resulting in incomplete conversion and prone to catalyst poisoning in subsequent processes.