Problems and optimization suggestions on flue gas recirculation technology for low nitrogen burners

There is a problem

1.Fan underload

Due to the recirculation of flue gas into the fan inlet, the volume of fresh air from the fan is reduced, which cannot provide the air volume required for boiler steam generation at 75t/h.

2.Condensation water causes corrosion

Because the high temperature smoke is mixed into the fresh air, there are more condensate water at the entrance of the backup fan and the low discharge point, which causes corrosion to the smoke duct and fan.

3.Self - operated gas relief valve can not adapt to the working condition well

For many times, the gas flow rate has been greatly reduced due to the freezing and condensation of the guide pipe of the self-operated gas pressure reducing valve, which endangers the normal production of the boiler. Also appears a pressure relief valve core adhesion, the valve can not adjust the pressure phenomenon.

4.No spare gas filter

There is no parallel backup or bypass line for the gas filter. In case of blockage or other faults, it will not be able to provide fuel for the boiler normally, which will lead to the shutdown of the boiler.

5.The water wall pipe was damaged during the removal of the flame guard belt

The demolition of the fireproof belt was done by artificial percussion drilling, which caused many impact pits on the water-wall pipe. After the demolition work is completed, the repair welding is carried out. But it does pose a long-term risk.

Optimization Suggestions

1.Add row setting

Set discharge is added at fan inlet and low point of pipeline to discharge the condensate water and reduce it.Corrosion, avoid condensation water on the fan operation to produce adverse effects, avoid condensation water with the wind.Go into the burner. At the same time, it should be noted that the condensation water with welding slag and other impurities, need to pay attention.Drain to prevent impurities from blocking the drain line.

2.Redesign of self - propelled gas relief valve

Because the gas in the refinery is easy to have trace amount of coke powder, it is suggested to select the pressure reducing valve that can adapt to the working condition, so as to create good conditions for the boiler's long period stable operation. At the same time, in the process of gas treatment should also strengthen the quality control, avoid the phenomenon of gas with coke powder.

3.A parallel gas filter is added

When there are problems with the filter, switch to another set of filter for operation, and disassemble and clean the blocked filter to ensure the continuous operation of the boiler.

4.Replace part of the water wall pipe in the flame retardant zone

In order to eliminate the impact pit caused by the water wall pipe in the construction process and the bad influence of repair welding in the later period, it is suggested to replace this part of the pipe section by selecting a machine.

5.Make special care plan for boiler operation during renovation

The construction and renovation will take one month. During this period, the boiler cannot be used for backup. If the boiler in operation is abnormal, it will have a huge impact on the steam supply of the whole refinery. Need to make the special care plan of the running boiler.