JPS6219799B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for suppressing thermal deformation of coke oven support metal fittings. As shown in Fig. 1, a general coke oven consists of a carbonization chamber 1 that carbonizes coal, a combustion chamber 2 that alternately adjoins this and supplies a carbonization heat source, and a heat storage chamber that preheats combustion gas and air. (not shown), a hearth lid 3,
It consists of an extruder 4 and a coke guide wheel 5. A kiln opening 10 is provided at both ends of the combustion chamber 2. For example, the furnace opening of the furnace body of various types of coke ovens as shown in FIGS. A protection plate 6 for each combustion chamber 2,
The entire furnace body is supported by being restrained by furnace body metal parts such as a backstay 7 and a door frame 8. In particular, near the kiln mouth, the structure to uniformly transmit the restraining force of the furnace hardware to the furnace body through the partition wall 12, and the structure to withstand the furnace temperature and the insulation structure are concentrated, resulting in a complex brick structure. It is becoming. Insulating brick 11 (second
(Fig.) serves to prevent heat dissipation from the end wall of the combustion chamber 2, and also to prevent excessive thermal deformation of the furnace metal parts due to the dissipated heat. As a result of examining the end wall bricks at the kiln mouth during the dismantling work of the coke oven, it was found that the insulation bricks 11 at the kiln mouth had turned black and the pores of the bricks were filled with precipitated carbon. In this way, the thermal conductivity λ of a fireproof and insulating brick impregnated with carbon is abnormally high at 2 to 5 kcal/m・hr・℃, and the thermal conductivity λ of a brick heat-treated in an oxidizing atmosphere is 0.2 Kcal/m・At hr・℃ or less, it remains the same as before use, but the strength has significantly decreased. A similar phenomenon was observed in the silica bricks, schaumite bricks, and other monolithic refractory layers in each part of the carbonization chamber. The cause of carbon deposition is estimated as follows.
In other words, (1) tar generated in the bricks near the hearth penetrates as a liquid phase, and (2) CO gas penetrates in the upper and middle parts of the furnace height as a gas phase, and iron oxides in the bricks at low temperatures. (3) When carbon is precipitated by the catalytic action of (3) Carbon is precipitated from CO gas as the oxygen partial pressure decreases. Considering that the operating life of a coke oven is 20 to 30 years, carbon deposition on the insulation layer bricks between the end wall bricks and the furnace body hardware, that is, behind the protective plate, is mainly due to the infiltration of CO gas. It is presumed that this is a developed product that has been reduced. The infiltration of furnace gas into the insulation bricks is caused not only by the communicating brick pores, but also by the opening of joints or cracks in the furnace wall bricks during the operation process, and the formation of gaps due to aging of the packing. This cannot be effectively prevented. Therefore, an object of the present invention is to obtain bricks with low porosity at the mouth of a coke oven, thereby reducing the amount of carbon deposited during operation. Carbon deposition in the insulating part of the kiln mouth of a coke oven cannot be avoided in practice, so in order to reduce the amount of carbon deposited, the inner lining is made of bricks with low porosity to prevent the deterioration of insulation properties due to carbon deposition. It is necessary to prevent this. In the present invention, as shown in FIG. 2, in the furnace mouth of the combustion chamber 2 of the coke oven, a heat insulating layer with a low porosity is provided between the partition wall 12 of silica bricks constituting the friue and the furnace hardware. Place brick 11. This insulating brick must have an apparent porosity of 17% or less, a fire resistance of SK27 or more, and a chemical composition with iron oxide (Fe ₂ O ₃ ) content of 1% or less. It won't happen. The reason why we limited this porosity to 17% or less is that 17%
This is because if the amount exceeds 100%, an effective heat insulating effect cannot be obtained when carbon is deposited. The required fire resistance is less than 1000℃, but if joints or cracks occur in the silica partition wall, the insulating bricks will be exposed to the friue temperature and the temperature will exceed 1000℃, so fire resistance above 1000℃ is required. must be ensured. Carbon deposition is caused by the catalytic action of iron oxides in the bricks.
It is produced by the reduction of CO in the temperature range of approximately 400 to 500°C, so it would be ideal to eliminate iron oxide altogether, but it is only possible to suppress it to less than 1% in brick manufacturing. Bricks that meet these conditions include high alumina bricks, siamots bricks, sillimanite bricks, cordierite bricks, low stone bricks, high silicate clay bricks, magurolith bricks, magnesia bricks, calcia bricks, There are fired bricks and cast bricks such as silica bricks and zirconia bricks. However, the partition walls, or furnace walls, are made of silica and are usually
Since it is more than 1kcal/m・hr・℃, unless it is a brick with a lower thermal conductivity as a heat insulating layer,
It becomes necessary to significantly increase the thickness of the layer, necessitating major design changes, and problems tend to occur in supporting the furnace body. For this reason, applicable furnace materials are limited to SiO ₂ -Al ₂ O ₃ systems. However, silica bricks and alumina bricks are excluded. According to the invention, in particular fired bricks or electroformed bricks are used. The reason is that these bricks do not have an increase in porosity due to binder gasification during use. In order to reduce the porosity of insulating bricks, a method of impregnating them with fine particles of refractory may be considered as a secondary treatment method for bricks. It is desirable that the impregnating material be of the same type as the base material brick. For example, it consists of 95% of a mixture of one or two types of alumina sol or silica sol, and 5% of soda glass powder (200 mesh or less), and is added to a colloidal solution with molasses or dextrin of any concentration as an adhesive. The brick is immersed in a vacuum container to adsorb fine refractory particles into the pores of the brick, and after immersion, it is dried at about 100°C. This treatment reduces the apparent porosity before impregnation to 17% or less. The fine powder in the colloidal liquid adsorbed into the bricks fills the small pores and reduces the pore size of the large pores.
It also seals the capillary pores that connect the pores, resulting in no air permeability. Conventionally, when using insulating bricks with a porosity of 80%, the thermal conductivity increased by more than 10 times.
By using the brick of the present invention, the thermal conductivity is increased.
The increase was only about 20%, making it possible to maintain insulation properties. In particular, if fused siliceous bricks are used, the effect of preventing carbon deposition will be significantly improved, and the heat insulation of the kiln mouth will be maintained for a longer period of time. Namely, fused silica (refractory level SK34, porosity 12
%, thermal conductivity 0.6 kcal/m・hr・℃) due to carbon penetration, even if the porosity is less than 1% and the thermal conductivity changes from 0.69 to 0.83 kcal/m・hr・℃, the amount of heat dissipated The increase will be limited to less than 10%. Additionally, as shown below, fused siliceous bricks have different properties from fired bricks, so
Shows useful performance in suppressing carbon deposition. (1) Extremely low coefficient of thermal expansion, spalling resistance,
It has good volume stability and maintains stable strength as a furnace structure. (2) Since it is a cast molded product, the surface is smooth and carbon is difficult to adhere to. Furthermore, since large blocks can be easily formed, the number of joints can be reduced and the amount of carbon deposited at the joints can be significantly reduced. Table 1 shows a comparison of the performance of conventional insulation bricks and insulation bricks used in the method of the present invention. In Table 1, the thermal conductivity is expressed using the thermal conductivity of conventional bricks before use as the standard (1). Fireproof insulation bricks before use are JISR2611
(1959) B3 or B2 bricks. Thermal conductivity of used refractory insulation bricks indicates the range of measured values of samples taken during intermediate repairs of the furnace.

[Table] Examples of the present invention are shown below. Table 2 shows the results of calculating the amount of heat dissipated on the surface of the protective plate in a coke oven using bricks used in the method of the present invention, and is expressed based on the amount of heat dissipated at the initial stage of operation in a furnace using conventional materials. For each furnace, measure the heat flow rate, surface temperature, and outside air temperature (21 to 25℃) on the surface of the protective plate using a dry heat flow meter and a surface thermometer to determine the representative values, and calculate the heat transfer coefficient (radiation heat transfer coefficient) for each furnace. and the convective heat transfer coefficient)
was calculated to determine the amount of heat dissipated. At this time, although the load factor was in the range of 107% to 110% as an operating condition for each furnace, the heat output including the generated gas sensible heat, coke sensible heat, and furnace body dissipated heat could be considered to be almost constant. For comparison, the amount of heat dissipated (kca/m ² hr) was calculated as the unit surface area of the protective plate on the coke side of one reactor group. As a result, in the case of conventional bricks, due to the significant penetration of carbon, thermal conductivity increases and the surface temperature of the protection plate rises significantly. However, in the case of the method of the present invention, since the penetration of carbon is suppressed, there is no large change in thermal conductivity and the temperature rise is small, and the effect of implementing the method of the present invention is obvious. In addition, since each furnace is currently in operation, the final improvement effect if carbon deposits continue is not clear, but compared with the number of years of operation, the effect of reducing the amount of carbon deposits in bricks with a small porosity is it is obvious.

[Table] According to the present invention, by reducing the amount of carbon deposited on the insulating bricks during operation, the insulation of the insulating bricks during operation is ensured. can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of a part of the coke oven. Second
The figure is a cross-sectional view of the furnace mouth of various types of coke ovens. 1... Carbonization chamber, 2... Combustion chamber, 3... Furnace cover, 4
... Extruder, 5 ... Coke guide car, 6 ... Protection plate, 7 ... Back stay, 8 ... Door frame, 10 ... Kiln mouth, 11 ... Insulating brick, 12
...Partition wall.

Claims (1)

[Claims] 1 The thermal conductivity of the bricks that constitute the heat insulating layer located between the furnace body hardware and the furnace wall bricks at the furnace mouth of the coke oven is less than 0.9kcal/m・hr・℃, and the fire resistance is SK27 (1610℃ ) or more, the iron oxide content is 1% or less, and the apparent porosity is 17% or less.
Controlling thermal deformation of coke oven support hardware, characterized by reducing the amount of carbon deposited in the heat insulating layer caused by gas generated during coal carbonization by using SiO ₂ -AlO ₃ based refractory bricks. Method.