central oxygen

This situation is typically caused by an insufficient capacity for central oxygen regulation; under high-load conditions, the pressure difference at the slag outlet increases, which requires a higher flow rate of central oxygen in order to lengthen the flame and melt the slag. Increasing the flow rate of central oxygen necessitates opening the valves. But the problem is that your central oxygen resistance will be greater than the peripheral oxygen resistance, resulting in insufficient oxygen supply to the center. In this situation, you definitely cannot reduce the valve opening any further; by doing so, the oxygen level at the center will be lower and the flame will become shorter. I just posted a new thread today titled “Weekly Topic” about external epoxy orifice plates; go take a look – it should be informative for you

We are center oxygen flow increase orifice plates; there is no outer epoxy.

That one on the central oxygen pipeline is not a process orifice plate; it’s just an orifice flow meter

After carefully examining the diagrams, it was indeed found that a orifice plate had been added to the outer epoxy section. Tests showed that when the oxygen level remained at 15–20%, reducing the amount of oxygen at the center allowed for better slag formation. The valve controlling the oxygen at the center was adjusted by 5% less than before, while the total amount of oxygen stayed the same. As a result, the flame extended downward, and the pressure at the slag outlet decreased; the maximum pressure there reached only 0.8. Thanks to the orifice plate in the outer epoxy section, the maximum flow rate was achieved. By reducing the oxygen amount at the center, the total oxygen level remained unchanged, and the oxygen flowed toward that area. Closing the valve further helped the flame to extend

It is wise to add an external epoxy orifice plate, as this allows the vaporization furnace to have more flexibility in adjusting the amount of oxygen supplied when operating under high loads! Although the slag port pressure difference has reached 0.8, which is not yet at the high threshold value, it is still somewhat high. Even though you have managed to reduce the slag port pressure difference using this method, you shouldn’t take it lightly; within 24 hours after the pressure difference returns to normal, keep a close eye on the ash and slag coming out of the lock hopper. By observing the changes in the ash, we can determine whether there are any changes in the flow pattern within the gasification furnace with regard to the absence of atomization. It would be better if no changes occur or if the situation improves; if the quality of the ash worsens, further adjustments will still be necessary

There is a flow meter on the external epoxy side; does the flow meter not have an orifice plate?

The external epoxy pressure difference (a larger pressure difference results in a faster oxygen flow rate) is the main factor contributing to the formation of the atomization angle; in addition, it is also related to the slurry pressure difference. The interaction between these two factors creates a sufficient atomization angle, which enables the flame length to be increased and the high-temperature zone to be shifted downward, thereby benefiting the slag outlet. In my opinion, raising the overall furnace temperature is the key factor for improving the slag outlet conditions. In other words, closing the central oxygen valve is done to increase the external oxygen level.

First, the oxygen ratio at the heart of our company is maintained at around 15% to 16% under all load conditions. It has been 7 years since it was put into operation in 2010, and I have been working in coal gasification for 9 years. Secondly, based on your question, an increasing slag outlet pressure difference indicates that the furnace temperature is not well controlled; this is caused by the fact that the slag does not have the necessary fluidity for proper discharge. The main reasons for this are: 1. Inadequate control of the furnace temperature; 2. Deterioration in the quality of coal, as reflected in changes in its ash content. Central oxygen is used solely to control the flow pattern and direction of the flame within the gasification furnace, and its role in controlling the slag outlet pressure difference is minimal. If the proportion of central oxygen is kept low, the collision of flames is reduced, which causes the temperature zones inside the furnace to shift towards the roof or the furnace walls near the nozzles, resulting in an increase in the temperature at the roof and on the furnace walls. A higher proportion of central oxygen causes the flames to move downward. This approach of adjusting the proportion of central oxygen in order to reduce the pressure difference at the slag outlet is not very effective, and it should be avoided in actual operations. Main efforts are focused on improving furnace temperature through oxygen addition and enhancing coal quality.