JP3787933B2 - Bulkhead refractory repair and strengthening method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for repairing and strengthening a partition refractory constituting a partition in a furnace.
[0002]
[Prior art]
A furnace having a partition in the furnace is generally known as a partition type heat exchanger, and a coke furnace is a typical furnace among them. The coke oven is a furnace for producing coke by dry distillation of coal, and a carbonizing chamber for storing coal and a combustion chamber for generating heated gas are alternately arranged via partition walls made of refractory. In the furnace, the partition walls are heated by the heated gas in the combustion chamber, and the heat is transmitted to the carbonization chamber on the opposite side of the partition walls. Coal in the carbonization chamber is pyrolyzed by heating, generating coke oven gas and proceeding with dry distillation.
[0003]
In general, refractories constituting the inner walls of industrial furnaces and molten metal containers, including the partition walls of coke ovens, are damaged by cracking or the like due to thermal spalling or the like. As a refractory repair method, a method of spraying a mixture of refractory powder and water to a damaged portion, that is, a wet spray method is known. However, since this method is performed after the furnace temperature is lowered, it takes time to cool the furnace and raise the temperature after repair work. Therefore, it is necessary to stop the operation of the furnace for a long time. In addition, this wet spraying method does not exhibit sufficient bonding strength to the sprayed refractory, and thus is easily peeled off with a slight impact. Therefore, this method is only used as a temporary measure.
[0004]
Therefore, thermal spraying has been proposed as a repair method for refractories. In this method, the refractory powder is made to be in a semi-molten or molten state in a flame composed of oxygen and fuel gas, or by burning aluminum or silicon, and adhered to the damaged part of the refractory. For example, Japanese Patent Application Laid-Open No. Sho 62-15508 discloses a flame sprayed material applied for such a purpose.
[0005]
Japanese Patent Publication No. 3-9185 discloses a high-silica material composed of a specific ratio of SiO ₂ , Al ₂ O ₃ , CaO, Fe ₂ O ₃ and Na ₂ O and forming a thermal spray repair body that can withstand long-term use. A thermally sprayed material is disclosed. In construction, these thermal spray materials are melted by a flame, collide with a repaired portion, and rapidly solidify to form a thermal spray body mainly composed of a glass phase.
[0006]
In an industrial furnace or the like, when the quartz brick that constitutes the furnace wall is severely damaged, transshipment of the damaged brick is performed. Brick transshipment is performed hot to avoid damage associated with cooling of existing bricks. For example, Japanese Patent Laid-Open No. 5-132355 discloses a hot-repaired quartzite brick for use in hot-replacement repair of a brick wall of a coke oven, which has excellent heat resistance and wear resistance. Yes.
[0007]
[Problems to be solved by the invention]
However, the sprayed body mainly composed of the glass phase described in Japanese Patent Application Laid-Open No. 62-15508 or Japanese Patent Publication No. 3-9185 crystallizes in the cooling process and transitions to the crystalline phase. Since the volume shrinks during this phase transition, cracking occurs. For this reason, the thermal spray repair body is insufficiently bonded to the base material and cannot be used for a long time. In particular, when the base material is denatured and the strength is reduced, cracks develop from the base material side and the thermal spray repaired body falls off. Therefore, the life of the thermal spray repaired body is not determined only by the intensity of the thermal spray earthquake and the spalling resistance, and there is a problem of the sprayed repair body falling off, and the life is about half a year.
[0008]
Moreover, in order to apply this method, it is necessary to specify a damaged part beforehand. However, the region is not limited to a portion that can be observed from the outside, and it is generally difficult to identify the damaged portion by observing the inside of the furnace.
[0009]
The hot transshipment repair technique described in Japanese Patent Application Laid-Open No. 5-132355 is a more reliable method than the flame spraying method, but involves a high-temperature heavy reinforcement work in the hot state and has a problem in the work environment. In addition, since the work takes a long time, it is necessary to stop the operation of the furnace for a long time.
[0010]
The present invention has been made to solve the above problems, can be repaired hot, can be easily carried out without specifying a damaged portion, and prevents the repaired body from falling off the repaired portion. Provide refractory repair methods that can be used.
[0011]
[Means for Solving the Problems]
The present invention provides a method for repairing and strengthening bulkhead refractories constituting a bulkhead in a furnace, wherein a gas containing a metal vapor or a metal compound vapor is supplied to one space of the bulkhead, and the metal vapor or metal is supplied to the other space. Supplying a reactive gas that reacts with the compound vapor to precipitate another solid metal compound, deposits the solid metal compound on the partition refractory, and then contains the metal vapor or metal compound vapor into both spaces Stop supply of gas and reactive gas, introduce inert gas into any space and apply pressure to measure leak, and if the leak amount exceeds a predetermined value, the metal vapor or metal performed by repeating the supply of gas and the reactive gas containing compound vapor and discontinuance and leakage measurements, where the leakage amount is equal to or less than a predetermined value, Rukoto to end the supply of gas to both the space The A repairing method of enhancing the partition wall refractory to symptoms.
[0012]
Next, for a gas containing metal vapor or metal compound vapor, the metal gas is preferably a metal having a high vapor pressure, such as Mg, and the metal compound gas is an alkyl metal, halide, oxyhalogen bonded to an alkyl group. Various compounds such as hydrides, hydrohalides and alkoxides can be used.
[0013]
For example, examples of the alkyl metal include Al (CH ₃ ) ₃ , Al (C ₂ H ₅ ) ₃ , Si (CH ₃ ) ₄ , Si (C ₂ H ₅ ) _{4 and the} like. Examples of the alkoxide include Al (C ₃ H ₇ O) ₃ , Si (CH ₃ O) ₄ , Si (C ₂ H ₅ O) _{4 and the} like. Examples of the halide include AlCl ₃ , SiCl ₄ , TiCl ₄ , and ZrCl ₄ . Examples of oxyhalides include Si ₂ OCl ₆ and ZrOCl ₂ . Hydrohalides SiH ₂ Cl _{2 and the} like.
[0014]
These may be used only with a gas of metal vapor or metal compound vapor, or may be diluted with a gas that does not react with these metal vapor or metal compound vapor. For example, N ₂ or Ar may be used as the dilution gas.
[0015]
As the reactive gas, a gas that reacts with the gas (metal vapor or metal compound vapor) containing the metal vapor or metal compound vapor and precipitates a solid of another metal compound is used. Here, the other solid metal compound may have a function as a refractory, but it is desirable that the coefficient of thermal expansion and the like are as equal as those of the refractory to be repaired. Therefore, it is preferable to use the same metal compound as the refractory to be repaired.
[0016]
As the reactive gas, for example, O ₂ , H ₂ O, CO ₂ , N ₂ , NH ₃ , N ₂ O, and various hydrocarbons can be used. Examples of the various hydrocarbons are alkanes such as CH ₄ , C ₂ H ₅ and C ₃ H ₇ , alkenes such as C ₂ H ₄ and C ₃ H ₆ , and alkynes such as C ₂ H ₂ .
[0017]
When O ₂ is used as the reactive gas, a metal oxide solid can be deposited by reaction with various metal vapors or metal compound vapors. The individual reactions are shown below.
[0018]
Mg + 1 / 2O ₂ → MgO
Al ₂ Cl ₆ + 3 / 2O ₂ → Al ₂ O ₃ + 3Cl ₂
SiH ₄ + O ₂ → SiO ₂ + 2H ₂
MgCl ₂ + 1 / 2O ₂ → MgO ₃ + Cl ₂
TiCl ₄ + O ₂ → TiO ₂ + 2Cl ₂
ZrCl ₄ + O ₂ → ZrO ₂ + 2Cl ₂
Al (CH ₃ ) ₃ + 15 / 2O ₂ → 1 / 2Al ₂ O ₃ + 3CO ₂ + 9 / 2H ₂
[0019]
When H ₂ O is used as the reactive gas, a metal oxide solid can be deposited by reaction with various metal vapors or metal compound vapors. The individual reactions are shown below.
[0020]
Mg + H ₂ O → MgO + H ₂
MgCl ₂ + H ₂ O → MgO + 2HCl
SiCl ₄ + H ₂ O → SiO ₂ + 4HCl
TiCl ₄ + H ₂ O → TiO ₂ + 4HCl
ZrCl ₄ + H ₂ O → ZrO ₂ + 4HCl
Al ₂ Cl ₆ + 3H ₂ O → Al ₂ O ₃ + 6HCl
Al (C ₂ H ₅ ) ₃ + 3H ₂ O → 1/2 Al ₂ O ₃ + 3C ₂ H ₆
Si (CH ₃ O) ₄ + 2H ₂ O → SiO ₂ + 4CH ₃ OH
Si (C ₂ H ₅ O) ₄ + 2H ₂ O → SiO ₂ + 4C ₂ H ₅ OH
[0021]
When CO ₂ is used as the reactive gas, a metal oxide solid can be deposited by reaction with various metal vapors or metal compound vapors. The individual reactions are shown below.
[0022]
Mg + CO ₂ → MgO + CO
SiH ₄ + 2CO ₂ → SiO ₂ + 2CO + 2H ₂
[0023]
When a mixed gas of CO ₂ and H ₂ is used as the reactive gas, a metal oxide solid can be deposited by reaction with various metal vapors or metal compound vapors. The individual reactions are shown below.
[0024]
MgCl ₂ + CO ₂ + H ₂ → MgO + CO + 2HCl
Al ₂ Cl ₆ + 3CO ₂ + 3H ₂ O → Al ₂ O ₃ + 3CO + 6HCl
[0025]
When a mixed gas of N ₂ and H ₂ is used as the reactive gas, a metal nitride solid can be deposited by reaction with various metal vapors or metal compound vapors. The reaction is shown below.
[0026]
Al ₂ Cl ₆ + N ₂ + 3H ₂ → 2AlN + 6HCl
[0027]
When H ₂ O is used as the reactive gas, a metal nitride solid can be precipitated by reaction with various metal vapors or metal compound vapors. The individual reactions are shown below.
[0028]
SiH ₄ + 4 / 3NH ₃ → 1/3 Si ₃ N ₄ + 4H ₂
3SiH ₂ Cl ₂ + 10NH ₃ → Si ₃ N ₄ + 6NH ₄ Cl
SiCl ₄ + 16 / 3NH ₃ → 1 / 3Si ₃ N ₄ + 4NH ₄ Cl
TiCl ₄ + 4 / 3NH ₃ → TiN + 4HCl + 1 / 6N ₂
ZrCl ₄ + 4 / 3NH ₃ → ZrN + 4HCl + 1 / 6N ₂
[0029]
When CH ₄ is used as the reactive gas, a metal carbide solid can be deposited by reaction with various metal vapors or metal compound vapors. The individual reactions are shown below.
[0030]
SiH ₄ + CH ₄ → SiC + 4H ₂
TiCl ₄ + CH ₄ → TiC + 4HCl
TiI ₄ + CH ₄ → TiC + 4HI
[0031]
When a mixed gas of C ₂ H ₅ and H ₂ is used as the reactive gas, a metal nitride solid can be deposited by reaction with various metal vapors or metal compound vapors. The reaction is shown below.
[0032]
TiI ₄ + 1 / 2C ₂ H ₅ + 3 / 2H ₂ → TiC + 4HI
[0033]
When a mixed gas of CH ₄ and H ₂ is used as the reactive gas, a solid metal carbide can be precipitated by reaction with various metal vapors or metal compound vapors. The reaction is shown below.
[0034]
CrCl ₃ + 3 / 2CH ₄ + 1 / 3H ₂ → 1/3 Cr ₃ C ₂ + 3HCl
[0035]
The gas of the metal vapor or metal compound vapor may be a mixture of a plurality of metals and a plurality of metal compound gases. Also, as for the reactive gas, a mixed gas other than the above-mentioned mixed gas of reactive gas may be used. In these cases, a precipitate composed of a plurality of components can be obtained according to the composition of each gas.
[0036]
The appropriate reaction temperature of the metal vapor or metal compound vapor gas and the reactive gas differs depending on the combination of the two.
[0037]
For combinations of alkyl metals with O ₂ and H ₂ O, temperatures in the range of 300-800 ° C. are desirable. This is because the reaction rate is too slow at less than 300 ° C., while the alkyl metal is thermally decomposed at temperatures exceeding 800 ° C., making it difficult to achieve the intended reaction.
[0038]
For combinations of alkoxide and H ₂ O, temperatures in the range of 200-700 ° C. are desirable. This is because the reaction rate is too slow at less than 200 ° C., while the alkoxide is thermally decomposed at temperatures exceeding 700 ° C., making it difficult to achieve the intended reaction.
[0039]
The combination of halide, oxyhalide, or hydrohalide with O ₂ , H ₂ O, CO ₂ , N ₂ , NH ₃ , N ₂ O, and various hydrocarbons is a temperature of 600 ° C. or higher. Is desirable. This is because the reaction rate is too slow below 600 ° C.
[0040]
In the combination of Mg vapor and O ₂ , H ₂ O, and CO ₂ , a temperature of 700 ° C. or higher is desirable. This is because part of the Mg vapor is likely to condense at the stage of transfer to the reaction site at less than 700 ° C., so that Mg cannot be effectively used for the intended reaction.
[0041]
Mg vapor may be generated by heating molten Mg. In this case, the heating temperature is preferably in the range of 700 to 1200 ° C. This is because the generation rate of Mg vapor is too slow below 700 ° C., whereas the generation of Mg vapor becomes intense when it exceeds 1200 ° C., and it becomes difficult to control the flow rate and pressure of the gas containing this. It is.
[0042]
Mg as a starting material may be ingot or powder. When Mg is a powder, it may be a single Mg or a mixed powder of Mg—CaO and Mg—Al. Since Mg powder is easily ignited, mixed powder is preferable.
[0043]
Mg vapor may be generated by reacting MgO and Al as follows.
3MgO + 2Al → 3Mg + Al ₂ O ₃
In this case, the reaction temperature is preferably in the range of 850 to 1700 ° C. This is because the reaction rate is too slow below 850 ° C., while on the other hand, when it exceeds 1700 ° C., the generation of Mg vapor becomes violent, making it difficult to control the flow rate and pressure of the gas containing this.
[0044]
The concentration of the metal vapor or metal compound vapor contained in the gas containing metal vapor or metal compound vapor (dilution gas) is 0.1 vol. % Or more is desirable. This is 0.1 vol. This is because the reaction rate is too slow at less than%.
[0045]
The concentration of the reaction gas contained in the gas containing the reaction gas (dilution gas) is 1 vol. % Or more is desirable. This is 1 vol. This is because the reaction rate is too slow at less than%.
[0046]
As a gas containing the reaction gas (dilution gas), when two or more kinds of gases are selected from O ₂ , H ₂ O, CO ₂ , and N ₂ , a pure gas may be mixed. Various combustion gases may be used. As the combustion gas, any gas obtained by burning natural gas, liquefied petroleum gas, kerosene, heavy oil, coal, coke oven gas, blast furnace gas, converter gas, or the like with air or oxygen can be used. Moreover, you may use the exhaust gas of various heating furnaces as needed. When CH ₄ is used as the reaction gas, natural gas or coke oven gas may be heated before use.
[0047]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the coke oven will be described. The wall of the coke oven (also called a partition wall) is usually made of silica brick. Therefore, a silicon compound is suitable as a metal compound for repair. Of the silicon compounds, SiCl ₄ is a thermally stable substance and is particularly desirable because it does not thermally decompose within the entire range of 900-1450 ° C., which is the furnace wall temperature during coke oven operation. As dilution gas or carrier gas of SiCl ₄ , dry air, N ₂ , inert gas, or the like can be used.
[0048]
H ₂ O is most desirable as a reactive gas component to be reacted with SiCl ₄ . This is because H ₂ O has a very high reaction rate with SiCl _{4 in the} above temperature range, so that the reaction proceeds unless the supply amount of H ₂ O falls below the stoichiometric value.
[0049]
As the H ₂ O gas, that is, water vapor, one generated in an ironworks can be used. Moreover, water vapor is contained in combustion gas such as an industrial furnace, and can be used. For example, if coke oven gas or blast furnace gas is burned with air, H ₂ O is changed to 1 to 25 vol. %, 5~30vol the CO _2. % Containing gas is obtained. At this time, if it is burned with excess air, a gas containing O ₂ can also be prepared. If O ₂ is enriched and steam is blown, the concentration of H ₂ O, CO ₂ and O ₂ can be increased while maintaining an appropriate temperature.
[0050]
FIG. 1 is a cross-sectional view showing a cross section of a coke oven. In the figure, 10 is a partition, 11 is a heating chamber, 12 is a heated chamber, 36 is a combustion gas inlet, 37 is a gas inlet, 40 is a differential pressure gauge, 47 is an introduced gas, and 49 is a combustion gas.
[0051]
First, a gas 47 containing SiCl ₄ is introduced into the heated chamber 12 from the gas inlet 37. At this time, the gas 47 containing a metal vapor or a metal compound vapor enters the inside of the damaged portion such as pores or cracks of the refractory in the partition wall 10 by supplying the gas 47 with slightly increased pressure.
[0052]
Next, the pressure inside the heated chamber 12 is made lower than that of the heating chamber 11, that is, the differential pressure of the heated chamber 12 with respect to the heated chamber 11 is made negative. Then, a gas (combustion gas) containing H ₂ O and CO ₂ enters the inside of the damaged portion such as pores or cracks of the refractory of the partition wall 10 from the heating chamber 11 side.
[0053]
Since the gas containing SiCl ₄ has already entered the pores and cracks of the refractory, it reacts with a reactive gas such as water vapor. As a result, as described above, a solid is deposited inside the crack and the fine crack is buried. Even in the case of a large crack, the reaction continues on the surface, and solid deposition continues on the surface of the refractory (fracture surface of the crack). Therefore, the surface of the crack is covered and protected with a layer of precipitate.
[0054]
As described above, the operation of alternately pressurizing the spaces on both sides of the partition wall 10 is performed after a predetermined time or a predetermined number of times, and after introducing a pressure into one of the spaces and applying pressure, the leakage measurement of the partition wall 10 is performed. When the leak amount becomes a predetermined value or less, the supply of gas into both spaces is stopped.
[0055]
For the evaluation of the leak amount, the amount of change in the differential pressure after a certain time or the value of the remaining differential pressure may be used. If the amount of change in the differential pressure is within the specified range or the remaining differential pressure value is greater than or equal to the predetermined value, the leak amount has fallen below a certain value, and the cracks in the partition refractory are sufficiently blocked. become.
[0056]
【The invention's effect】
In the present invention, the partition refractory is repaired by precipitating another solid metal compound from a gas containing metal vapor or metal compound vapor, so that it can be repaired hot and the damaged portion is specified. It can be carried out easily without any problems. Further, by depositing the same metal compound as the refractory as another solid metal compound, it is possible to solve problems such as dropping off the repaired portion of the repair body. Furthermore, since the leak measurement of the partition walls is performed using an inert gas, the repair status can be confirmed by a simple method.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a cross section of a coke oven.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Partition 11 Heating chamber 12 Heated chamber 36 Combustion gas inlet 37 Gas introduction port 40 Differential pressure gauge 47 Introduction gas 49 Combustion gas

Claims (1)

In the method of repairing and strengthening bulkhead refractories constituting the bulkhead in the furnace, a gas containing metal vapor or metal compound vapor is supplied to one space of the bulkhead and reacts with the metal vapor or metal compound vapor in the other space. Then, a reactive gas for depositing another solid metal compound is supplied, and the solid metal compound is deposited on the partition refractory, and then the reaction with the gas containing the metal vapor or metal compound vapor into both spaces is performed. Stop supply of reactive gas, introduce inert gas into any space and apply pressure to perform leak measurement, and if the leak amount exceeds a predetermined value, contain the metal vapor or metal compound vapor gas and repeatedly performed by the supply and stop the leakage measurement of the reactive gas, where the leakage amount is equal to or less than a predetermined value, characterized that you end the supply of gas to both the space Interval Repair strengthening method of the refractory.

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