Common faults and elimination of blast furnace coal injection system

Once the blast furnace coal injection system fails, it must be treated in time to ensure normal coal injection and reduce the impact on the blast furnace operation. To prevent the coal injection system from malfunctioning, it must first be operated reasonably. It is not easy to malfunction during the normal blowing process, and it is easy to cause some failures when the tank is poured.

 

2 coal injection system composition and operation

The blast furnace must first be notified before pouring the tank, paying attention to fluctuations. The correct tanking procedure is:

(1) Close the coal valve to ensure that the pulverized coal in the line is purged;

(2) closing purge valve, quick shut-off valve, injection valve and pressure-replenishing valve;

(3) opening the blowdown tank discharge valve and the pressure equalizing valve;

(4) When the pressure of the blowing pipe drops to zero, the bell valve under the coal storage tank is filled with coal to the injection tank;

(5) After the coal powder in the coal storage tank is discharged, the electronic scale is zero, and the bell valve is closed;

(6) closing pressure equalizing valve;

(7) Open the charging valve under the coal tank, and the lower filling valve is closed after the tank pressure is normal.

Open the spray blow valve, quick shut-off valve, spray gun inlet valve and pressure-replenishing valve to resume normal coal injection.

 

3 common faults in the production process

3.1 The mixer is disconnected before and after the soft connection

(1) Close the coal valve and stop feeding the coal;

(2) Close the purge valve, the quick shut-off valve, and the spray gun inlet valve;

(3) Start the exhaust fan, blow the indoor N2, clean the site, and replace the soft connection;

(4) Inform the blast furnace to spray coal normally.

 

3.2 explosion-proof membrane blasting

(1) Explosion-proof membrane blasting of coal-collecting tanks and coal storage tanks caused by non-pulverized coal explosions, coal injection tanks can continue to spray coal, and notify equipment maintenance personnel to replace explosion-proof membranes.

(2) Due to the explosion of the explosion-proof membrane of the coal-collecting tank and the coal-collecting tank caused by the explosion of coal powder, the spray air blower is changed to N2, and the coal powder of the spray pipe is cleaned and the coal injection is stopped.

(3) If the explosion-proof membrane of the coal injection tank is blasted, the coal injection will be stopped immediately, and the cause of the explosion will be inspected and notified, and the blast furnace will be notified. If it is caused by non-pulverized coal explosion, after the replacement of the blasting membrane is completed, normal coal injection will resume. If it is caused by pulverized coal explosion, the fire source is treated first, after the explosion-proof membrane is replaced. All were transferred to N2.

 

3.3 The temperature of pulverized coal in the tank exceeds 70 °C

When the pulverized coal temperature in the pulverized coal tank exceeds 70 °C, all of them are changed to N2 coal injection. After the pulverized coal in the spray tank is completely sprayed, the tank inspection and the source of the fire extinguishing are carried out.

 

3.4 compressed air suddenly stopped

Stamping, pressure compensation, fluidization and injection are all converted to N2 coal injection. If there is no N2 facility, stop the coal injection and notify the blast furnace.

 

The 3.5N2 pressure suddenly drops to full-use compressed air injection coal. After the pulverized coal in each pulverized coal tank is sprayed, the N2 pressure can still not be recovered, then the injection of bituminous coal is stopped, and if the conditions permit, it can be changed to anthracite.

 

3.6 When the tank is inverted, the bell valve cannot be opened.

(1) Check the limit position of the electromechanical equipment and whether the transmission steel rope is down;

(2) If non-electromechanical problems are solved, open the valve to release the pressure of the coal storage tank by 0.2 to 0.25 MPa, and then close. Open the charging valve under the coal storage tank so that the pressure is slightly higher than the pressure of the coal injection tank by 0.03 MPa, and then open the bell valve, and repeat the cycle until it is opened.

 

3.7 The coal storage tank is too full, and the upper bell valve cannot be closed.

Close the discharge valve and open the charging valve on the storage tank for 2~5s. Repeat this many times until the upper bell valve is closed.

 

3.8 mixer blockage

phenomenon:

(1) The coal flow at the tuyere disappears.

(2) The pressure of the blowing pipe drops to the level of the hot air pressure.

Approach:

Stop spraying coal, remove the mixer, and remove any internal debris.

 

3.9 filter blockage

Phenomenon: The pressure difference between the filter increases before and after, and the amount of coal injected decreases.

Treatment: stop spraying coal and remove its internal debris.

 

3.10 Coal line plugging

phenomenon:

(1) The flow of coal at the tuyere disappears;

(2) The front end is blocked, and the injection pressure is close to the pressure of the conveying medium;

(3) The back end clogging spray pressure is close to the blast furnace hot air pressure.

 

3.11 gun jam

phenomenon:

(1) There is no coal flow at the tuyere;

(2) The pressure of the injection branch pipe is close to the pressure of the wind source (multiple pipelines).

Treatment method:

(1) Open the spray gun reverse blow valve;

(2) Replace the spray gun when it cannot be blown.

 

3.12 Injecting system exceeds 80 °C in each tank

Treatment: (1) Disposal of the tank, spray all the coal powder in the tank as soon as possible, and then re-spray after the temperature drops to normal.

(2) Switch to nitrogen blowing to change the blowing source and charging pressure from compressed air to full nitrogen.