Adjustment of coking heating furnace

Is it that the ratio of wind and the proportion of design positive pressure are insufficient?

1. A high temperature in the furnace chamber of a heating furnace does not carry any specific meaning; it is the temperature at the furnace outlet that is important. A high outlet temperature indicates that a large amount of heat enters the convection section, where it is not fully utilized in the radiation section. 2. The surface temperature of the furnace tube is not high; as long as the temperature of the medium at the outlet of the radiant furnace tube is sufficient, it does not have any particular significance. The surface temperature of the furnace tube is influenced by various factors; in particular, a low level of the film coefficient of the medium on the inner side of the tube (resulting in less coking and scaling) facilitates heat transfer, which to some extent indicates that the heat intensity per unit area is satisfactory. 3. For media with a high tendency to coking, there are significant differences in the surface temperature of the furnace tubes at the beginning and end of their operation; the surface temperature of the furnace tubes becomes very high once coking occurs. 4. If these factors are ruled out, the air supply can be adjusted so that the flame does not become too long, and the amount of air used can be reduced while ensuring proper combustion. 5. The length of the flame is related to the structure of the burner; if the fuel nozzles are large, it becomes difficult for the fuel and air to mix properly, resulting in a longer flame. Therefore, the angle, diameter, and number of nozzles need to be matched to the air supply, so as to keep the temperature at the center of the flame from being too high, ensure thorough mixing with the air, achieve a favorable combustion condition, and reduce nitrogen oxides. 6. For a given burner, it is advisable to use it within its efficient operating range; operating it at too high or too low a load will degrade the combustion efficiency

The poster has provided too little information; what are the temperature of the furnace chamber in the coking heater and the surface temperature of the furnace tubes? Whether something is high or not is merely a subjective judgment, which is not conducive to analyzing and solving problems. Agree with the opinion from the fourth floor. One additional point: A low surface temperature of the furnace tubes indicates that coking in the tubes is unlikely, and the processing load is not exceeding the design values. A high furnace temperature is related to excessive negative pressure or insufficient air supply; it is also necessary to check whether the air preheating temperature and the temperature after heat exchange with the fuel gas are within the specified ranges.

Reduce the negative pressure in the furnace; the flame should not be too long – it is best to keep it between 2-3 meters.

Adjustments: 1. Determine the position of the thermocouple. 2. Reduce the flame height in the burners located below that thermocouple. 3. Adjust the flame heights of the other burners so that they are roughly the same. 4. Adjust the air flow to keep the oxygen level and the negative pressure inside the furnace within the requirements specified by the process parameters.

Check the combustion of the flame in the furnace – is the flame too high below the furnace thermocouple?