Common Problems of Coke Ovens and Technical Measures (1)

1.How does the "Blasting" sound often heard during the exchange of coke ovens?

"Blasting" is caused by the mixing of coke oven gas and air in the brick gas duct to ignite and backfire. Generally, "blasting" occurs about 10-20s after the exchange. Most of them occur in brick gas ducts where the updraft is changed to the downdraft.

The common reasons are:

(1) The top wire of the exchange cock is too loose, resulting in air leakage.
(2) Air leakage in the horizontal and vertical pipes of the basement.
(3) When changing the orifice plate, the hair blue screw was not tightened after 15~20 seconds after the addition and subtraction cock was closed, causing air to be sucked in, resulting in "fire".
(4) The exchange cock is not opened or closed properly, the angle of the cock is not enough, or the cock has been rotated 90° but not fully closed, which may cause air leakage and air intake from the carbon removal port.
(5) The core and shell of the exchange cock are not well ground, corroded or lubricated, and air leaks even when fully closed.
(6) In violation of the pressure system, the graphite protective layer of the carbonization chamber was burned, and the raw gas leaked.
(7)  The brick gas pipe is leaking.

2.Emergency treatment for a big fire in a basement gas pipe?

When the pipe diameter is above 100mm, gradually close the gas source valve, and when the pressure drops to about 500Pa, use a steam foam fire extinguisher to extinguish the fire, and pass nitrogen and steam to cut off the gas to achieve fire extinguishing. If the diameter of the pipe is below 100mm, shut off the gas source and pass nitrogen and steam to extinguish the fire.

3.How to deal with a small fire in the basement gas pipe?

Wear a gas mask and put out the fire with yellow mud, wet sacks or a fire extinguisher.

4.How does the exhaust gas travel?

The generated exhaust gas passes through the cross hole to the descending fire channel, and then passes through the ramp, downflow regenerator, small flue, and sub-flue to the root of the chimney, and is pumped away by the chimney and discharged into the atmosphere.

5.What is the role of the exhaust plate?

It controls the amount of air entering the coke oven heating system and the amount of blast furnace gas, while also controlling the exhaust gas generated by the heating system.

6.What are the heating equipment of the coke oven?

Gas pipeline, waste gas pan, gas preheater, gas mixer, addition and subtraction cock, exchange cock, water seal tank, switch, flow orifice, temperature and pressure measurement tube, etc.

7.Why doesn't the coke oven gas pass through the regenerator?

Coke oven gas contains a large amount of methane and other hydrocarbons. These substances decompose at high temperatures and produce free carbon or graphite deposits that can easily block checker bricks or chutes. In addition, coke oven gas has a higher calorific value and does not need to be preheated to a temperature as high as blast furnace gas.

8.Why should coke oven gas be preheated to 45℃?

Because the coke oven gas contains some unrecovered tar, naphthalene and other substances, these substances condense when the temperature is low, and often block the pipes in the gas pipe cock, orifice plate or small pipe diameter, which will seriously affect The coke oven is heated evenly. 

9.What are the conditions for gas combustion and complete combustion?

Combustion conditions: combustion-supporting agent, ignition point.

Conditions for complete combustion: sufficient air and full contact with fuel; sufficient combustion space and time; combustion products can be discharged smoothly.

10.What are the conditions for the explosion?

The mixing ratio of air and combustibles is within the explosive limit; explosive gas encounters fire sources or red hot objects.

11.When using blast furnace gas, why sometimes a positive pressure is generated at the gas mound?

The sealing wall of the regenerator leaks, sucking in a large amount of air, which prevents the gas from passing through, resulting in positive pressure at the gas mound; the checker bricks of the regenerator block, the gas is blocked, and the positive pressure is generated at the gas mound.

12.Why should the combustion chamber be divided into many standing fire channels?  

Dividing the combustion chamber into many "cells" can increase the structural strength of the furnace body, and because it increases the area of radiant heat transfer, it is conducive to radiant heat transfer. Dividing the combustion chamber into many vertical fire channels can force the hot air flow after combustion to be evenly distributed along the length of the combustion chamber to achieve the purpose of uniform heating of the carbonization chamber.

Post time: Jan-05-2022