The negative pressure in the furnace chamber of the heating furnace fluctuates too greatly
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Due to the technological characteristics of our unit, there are periodic fluctuations of several degrees in both the inlet and outlet temperatures of the heating furnace. The designed load of the heating furnace is high, while the actual operating load is low; the opening degree of the flue dampers is less than 20%. The negative pressure inside the furnace chamber fluctuates significantly, and temporary positive pressures can occur in the flue dampers and the convection chamber (the DCS system cannot detect these positive pressure values). Several furnace negative pressure gauges are triggering alarms frequently. Could someone expert help analyze what the reason is?
This is caused by the large gap between the designed load and the actual operating load. Due to the overly high basic design requirements, all combustion and exhaust systems are designed for higher loads. When the actual operating load is lower, the regulation of these combustion and exhaust systems is not sensitive enough to control the furnace pressure, which can result in significant fluctuations in furnace pressure
This is caused by the large gap between the designed load and the actual operating load. Due to the overly high basic design requirements, all combustion systems and exhaust systems are designed for higher loads
.....The design load of the heating furnace is high, while the actual operating load is low; the opening degree of the flue dampers is less than 20%, and the negative pressure in the furnace chamber fluctuates significantly..... As you said, this is due to the high design load and low actual load. Consider this solution: first, check whether the current actual heat load can meet the process requirements (or, under the existing actual heat load that already meets the process requirements), and then adjust various parameters in sequence.
Is it caused by too low a load, resulting in large fluctuations in the gas volume?
If the exhaust fan is variable frequency, reduce the frequency and try using a larger baffle. Or it’s fine to make the value slightly more negative to increase the oxygen content; we need to see if stability can be achieved. Or maybe we shouldn’t focus on combustion efficiency for now; under the condition of ensuring a stable temperature, let’s try to increase the load
When the oxygen content is high, transient positive pressures continuously occur near the convection chamber of the heating furnace; this is likely caused by secondary combustion at the flue dampers. Due to the characteristics of the manufacturing process, there are slight fluctuations in the gas consumption of the heating furnace, and the negative pressure gauge in the furnace triggers alarms too frequently