Skip to content
LMM Group

Basic knowledge of coke oven protection equipment and adjustment and control technology methods

The role of furnace protection equipment

The main function of the furnace protection equipment is to utilize the potential energy of the adjustable spring. Continuously apply sufficient, evenly and reasonably distributed protective pressure to the masonry. This allows the masonry to remain intact and tight under its own expansion and external forces, thus ensuring the normal production of the coke oven.

  1. The longitudinal expansion of the furnace body and the role of furnace protection equipment;

The longitudinal expansion of the furnace body is absorbed by the expansion joints located in the chute area and the furnace top area. Under normal circumstances, the resistance wall only produces a limited outward tilt. When the masonry expands longitudinally, it produces an outward thrust on the resistance walls at both ends.

At the same time, the combined structure of the resisting wall and longitudinal braces gives protective pressure to the masonry. The failure of the longitudinal braces is the main reason why the resistance wall tilts outward. This is not only detrimental to the tightness of the furnace body, but also causes the carbonization chamber wall to tilt outward in a fan shape.

  1. The lateral expansion of the furnace body and the role of furnace protection equipment;

There is no expansion joint when the furnace body expands laterally (i.e., in the longitudinal direction of the combustion chamber). During the drying period, the furnace body gradually elongates laterally as the furnace temperature increases.

Within 2 years after being put into operation, as silica continues to transform into tridymite, the furnace body continues to elongate and then gradually stabilizes.

Under normal circumstances, the annual elongation is less than 5mm. It is required that the high protective pressure exerted by the furnace protection equipment on the masonry should be compatible with the expansion of each part.

  1. Other functions of furnace protection equipment;

The lateral pressure generated by the expansion of coal during the coking process and the compression of the coke cake when pushing coke causes the entire combustion chamber to be subject to bending stress and generate tensile stress on the elongated side.

The temperature difference in the furnace wall from the carbonization chamber side to the combustion chamber side also causes tensile stress in the carbonization chamber wall.

Therefore, the role of the furnace protection equipment is also to use protective pressure to offset these tensile stresses.

In addition, the furnace body is subject to strong impulse when the furnace door is opened and closed. The static bending friction generated after the coke cake is compressed during coke destruction requires furnace protection equipment to tighten the masonry in order to have sufficient structural strength. In addition, the furnace column is also the support for equipment such as the coke side operating table and gas collecting pipe.

Coke furnace

Coke oven door

The doors of coke ovens are generally iron-on-iron self-sealing, that is, knife-edge doors. The tightness of the doors is closely related to preventing smoke and fire, as well as the deformation and failure of the furnace frame and furnace columns. Therefore, the furnace door, which is not usually a furnace protection device, is actually a very important furnace protection device.

The outer shell of the furnace door is made of pig iron, and is equipped with a lifting hook, a knife edge bracket and a top screw device. It also comes with the horizontal iron and bolts for hanging the furnace door. The horizontal iron on the furnace door is stuck on the hook of the furnace door frame, and the furnace door is placed in the middle of the furnace door frame. When installing the furnace door, tighten the horizontal iron bolts.

When removing the door, first loosen the bolt, turn the horizontal iron to disengage the hook, and then the furnace door can be removed. There is no brick groove on the inside of the furnace door, and the groove is lined with clay bricks. When the lining brick is too thin, the heat preservation of the furnace head is not good and the heat dissipation is large, which increases the heat load of the side fire channel, easily reduces the temperature of the furnace head, causes coking of the furnace head, and reduces the coke quality.

Whether the furnace door knife edge is intact has a lot to do with preventing smoke and fire. For this reason, when the furnace door is removed, the residual substances such as tar residue and coke powder on the knife edge, furnace door frame and furnace door lining bricks should be cleaned immediately.

Otherwise, the residue will accumulate thicker and thicker, and the furnace door knife edge will gradually lose its self-sealing function, causing smoke and fire.

Due to the frequent lifting and hanging of the furnace door and its contact with the atmosphere, the temperature changes drastically, so the furnace door knife edge and lining bricks are easily damaged. For this reason, coke ovens are equipped with oven door repair stations, and oven door repair work is carried out on a scheduled basis.

Knocking knife edge The furnace door knife edge is made of flat steel and fixed with bolts. When adjusting, loosen the screw and tap the fixing clip to make the blade edge close to the furnace door frame.

A kind of knife edge with a cam clip. It uses a clip with a cam to catch the knife edge. The cam resists the knife edge. When external force is applied to the knife edge, the radius of the cam in contact with the knife edge will increase as the bolt rotates. large to prevent the blade edge from receding.

Coke oven door coke oven door

Protective panels and furnace door frames

The main function of the protective plate and furnace door frame is to distribute the protective pressure evenly and reasonably on the masonry, while ensuring the sealing between the furnace head masonry, protective plate, furnace door frame and furnace door knife edge. Therefore, it is required to be close to the burner and not have excessive curvature.

The furnace door frame is used to fix the furnace door. To this end, the furnace door frame is required to have a certain strength and rigidity. The machined surface should be smooth and straight so as to be in close contact with the knife edge of the furnace door and seal the furnace door.

When installing the furnace door frame, it should be aligned vertically, and the sealing material should be filled evenly around it and pressed tightly. The ribs around the furnace door frame can reduce the direct contact of smoke from the furnace door with the furnace column and protect the furnace column, so it cannot be too short.

During production, the knife cover of the furnace door frame should be kept clean so that the knife edge of the furnace door can be in close contact with it to avoid smoke and fire.

durability of coke oven doors Coke Oven Door And Frame coke ovens

Stove columns, braces and springs

  1. The function of the furnace column;

The furnace column is welded with I-beam (or channel steel). It can also be made of special square hollow steel and installed on the outside of the burner protection plate on the machine and coke sides. The upper and lower horizontal braces tighten the furnace columns on both sides of the machine and coke.

Large springs are installed on both sides of the machine side of the upper horizontal brace and the machine focus of the lower horizontal brace. The upper horizontal brace on the burnt side is grilled when it is burnt and pushed out, so there is no spring.

A number of small springs are installed in the furnace column along the height direction. The furnace column is the most important component of the furnace protection equipment.

The function of the furnace column is to transfer the pressure of the spring to the furnace body. As long as this pressure keeps the cracks and seams of the bricks in a compressed state, the furnace body elongation can be controlled to make the furnace body complete and tight. The furnace column also plays the role of erection machine, coke side operating platform, and supporting gas collecting pipe.

In production, the three-line method is generally used to measure the curvature of the furnace column. The three-wire method is to resist the walls at both ends of the coke oven. Set up the upper, middle and lower measuring wire frames at the elevations of the upper and lower horizontal irons and grate bricks of the furnace door respectively, and install three filaments with a diameter of 1 to 1.5 mm that are tightened with elastics along the direction of the coke oven body. The three lines should be on the same vertical plane without touching anything. Then measure the horizontal distance from the furnace column to the steel wire. The calculation formula is:

W=(a-b)+(c-d)h/ H;

W—furnace column curvature;

a—The distance from the upper line to the furnace column;

b—The distance from the center line to the furnace column;

c—The distance from the lower line to the furnace column;

h—the distance from the upper line to the center line;

H—The distance from the upper line to the lower line;

The measurement cycle of the furnace column curvature is stipulated as follows: once a month, the furnace column should be oiled and maintained once a year.

When measuring, pay attention to the line of sight perpendicular to the steel ruler. The steel ruler should be placed horizontally. The scale lines on the ruler should be parallel to the steel wire. Read the distance from the steel wire to each measurement point and make a record.

The measurement data must be compared with the last measurement data. When the allowable tolerance is exceeded, the cause should be found out in time and dealt with.

The curvature of the furnace column normally does not exceed 25mm. When adjusting, the spring pressure and the gap between the furnace column and the protective plate should be considered comprehensively.

The maximum curvature cannot exceed 50mm. When determining the curvature of the furnace column, it should be noted that the curvature obtained by the formula method or the chart method should be subtracted from the curvature of the furnace column in the free state to obtain the actual curvature of the furnace column due to the expansion of the furnace body.

  1. Tie

The braces used in coke ovens are divided into two types: horizontal braces and longitudinal braces. The horizontal braces are made of ∮50mm round steel and are installed on the top and bottom of the furnace along the length of the combustion chamber.

The upper brace is placed in the brick groove on the furnace roof, and the lower brace is buried in the furnace base platform on the machine and coke sides.

The material of the tie bars is generally low carbon steel. It has the highest strength limit and the lowest elongation at 250~350°C. As the temperature increases, the strength decreases significantly and the elongation increases.

The diameter of the tie bars tends to become thinner in places with higher temperatures such as the riser tube hole and coal loading hole. In addition to the higher temperature near the riser tube, there is also corrosion from ammonia water, so the tie bars become thinner faster. The thinning of the tie rod can be detected by the load of the large spring often becoming smaller.

The longitudinal braces are made of flat steel and are located on the top of the furnace. Its function is to tighten the resistance walls at both ends along the length of the oven group to control the longitudinal expansion of the coke oven.

Both ends of the longitudinal braces are inserted into the resistance wall and equipped with spring groups to maintain a certain load. Longitudinal braces are very important for the furnace group, especially for keeping the end combustion chamber intact.

  1. Spring

There are two types of springs: large and small. The spring group consists of large and small springs and is installed on the upper and lower horizontal braces of the coke oven machine and the coke side oven column.

Several sets of small springs are also installed at different heights of the furnace column. The spring can reflect the pressure exerted by the furnace column on the furnace body, making the furnace column close to the protective plate, and can control the force on the furnace column to prevent the furnace column from being overstressed.

The pressure on the upper and lower spring groups of the furnace column indicates the total load on the furnace body. The pressure on a small spring can only indicate the distribution of load at each point.

Within the maximum load range of the spring, the load is proportional to the amount of compression. During the oven and production process, the load of the spring must be checked and adjusted frequently.

The measurement cycle of springs in production is generally once a month. According to the selected measurement points, the compression amount of the large and small springs is measured and accurate records are made.

After the measurement is completed, determine the load value of the spring according to the pressure of the spring according to the measured value, and fill in the record form.

When the spring pressure exceeds the specified value, the adjustment should be considered based on the curvature of the furnace column and the gap between the furnace column and the protective plate.

The working status of each spring should be checked frequently. Clean and refuel each spring and tie-bar thread once a quarter to make the spring compress the furnace column. If the spring is found to be pressed or broken, replace it in time, but effective measures must be taken to prevent the furnace column from moving outward.

The springs must be tested before installation to measure the relationship between the compression amount and the load of each spring, and then group and register them, and install them in groups.

The test data of each group of springs should be saved as original data for inspection and comparison. The upper large and small spring groups are prone to elastic fatigue during long-term production and use, and open flame grilling will accelerate fatigue.

Once a failed spring is found, it should be dealt with promptly. Large and small spring groups and protective covers can extend the service life.

Coke Oven Door And Frame

Coking Equipment Manufacturer
coke ovens
coke oven door

Leave a Reply

Your email address will not be published. Required fields are marked *

Contact Us