​THERMAL SPRAYING METHOD
​TECHNICAL FIELD
[0001]
​THERMAL SPRAYING METHOD BY THERMITE THERMAL SPRAYING METHOD
​BACKGROUND TECHNOLOGY
[0002]
​Conventionally, as a thermal spraying apparatus for forming a refractory composition by a thermite thermal spraying method, there is known a thermal spraying apparatus for forming a refractory composition by carrying and injecting a raw material powder containing a refractory powder (refractory aggregate) and a combustible powder (for example, metal powder) by a supporting carrier gas (oxygen gas) and burning (igniting) it (for example, Patent Document 1)
​Specifically, Patent Document 1 describes a technique for injecting a carrier gas into an ejector by a jet nozzle, mixing the raw material powder and the carrier gas in an ejector, guiding the mixed mixture to the downstream side along a conduit (discharge conduit) of the conveyance path, injecting the mixture by the injection means, and burning the injected mixture to form a refractory composition
​PRIOR ART DOCUMENT
​PATENT DOCUMENT
[0003]
​PATENT DOCUMENT 1: JAPANESE PATENT NO. 5814699
​SUMMARY OF INVENTION
​PROBLEM TO BE SOLVED BY THE INVENTION
[0004]
​In such a thermal spraying technique, in order to efficiently and quickly form a target refractory composition, it is necessary to inject (mass-inject) a large amount of raw material powder to be the source of the refractory composition.. However, the inventors of the present invention have been found to have the following problems (1) to (3) when a mass injection test is performed using the thermal spraying apparatus of Patent Literature 1.
​(1) When a large amount of injection is performed, the amount of injection is inevitably increased, so that the adhesion property of the raw material powder to the surface to be constructed (hereinafter, simply referred to as "adhesion" is simply referred to as "adhesion") due to the rebound loss.. As a result, a reduction in the diameter of the tunnel is reduced.
​(2) When a large amount of injection is performed, the frequency at which the mixture comes into contact with the conduit (discharge conduit) of the conveyance path is increased, and the discharge conduit is worn
​(3) When the cross-sectional area of the injection port of the injection means is increased in order to perform mass injection, the flow velocity of the mixture injected from the injection port becomes low, and the risk of occurrence of a phenomenon in which the ignition occurs in the reverse direction to the conveyance direction of the backfire (phenomenon in which the mixture advances in the direction opposite to the conveyance direction of the mixture) is increased.
​In the present invention, "mass injection" is a "mass injection" in which the injection amount of the raw material powder is approximately 100 kg／ H or more.
[0005]
​To provide a thermal spraying method capable of suppressing reduction of adhesion, abrasion of a discharge conduit, and occurrence of backfire when performing mass injection.
​MEANS FOR SOLVING THE PROBLEM
[0006]
​As a result of the test and study performed by the present inventors, the flow rate of the carrier gas, the flow velocity of the carrier gas jetted from the jet nozzle, the flow velocity of the mixture in the flow passage of the discharge conduit, and the ratio of the cross-sectional area of the injection port of the injection means to the cross-sectional area of the straight part of the discharge conduit (the cross-sectional area of the injection port of the injection means).／ the four parameters of "the cross-sectional area of the straight part of the discharge conduit" are particularly important parameters for solving the problem, and the present invention is completed by specifying an appropriate range of these parameters.
[0007]
​That is, according to one aspect of the present invention, the following thermal spraying method is provided
​THERMAL SPRAYING METHOD USING THERMAL SPRAYING APPARATUS FOR FORMING REFRACTORY COMPOSITION BY INJECTING AND BURNING MIXTURE OF RAW MATERIAL POWDER CONTAINING REFRACTORY POWDER AND COMBUSTIBLE POWDER AND SUPPORTING CARRIER GAS
​The injection amount of the raw material powder is 100 kg／ H or more,
​THERMAL SPRAYING DEVICE
​storage means having a put-out port for storing the raw material powder and putting out the raw material powder,
​an ejector for sucking the raw material powder from the put-out port by the flow of the pressurized carrier gas and mixing the carrier gas and the raw material powder to form the mixture,
​and an injection means for injecting the mixture generated by the ejector,
​THE EJECTOR IS PROVIDED WITH THE SAME
​CONTAINER HAVING INTERNAL SPACE COMMUNICATING WITH THE OUTLET,
​injection nozzle for jetting the pressurized carrier gas from the tip to the internal space,
​and a discharge conduit having one end communicating with the internal space and guiding the mixture to the other end from the one end along the flow path,
​The flow rate of the carrier gas is 30 (Nm3)／ H) or more,
​The flow velocity of the carrier gas jetted from the jet nozzle is 602 (m)／ (S) or more (1180 (M)).／ S) or less,
​The flow velocity of the mixture in the flow path of the discharge conduit is 63 (m)／ (S) or more (283 (M)).／ S) or less,
​The ratio of the cross-sectional area of the injection port of the injection means and the straight part of the discharge conduit (the cross-sectional area of the injection port of the injection means)／ and the cross-sectional area of the straight part of the discharge conduit is 1-4.
​EFFECT OF THE INVENTION
[0008]
​The present invention makes it possible to suppress reduction in adhesion, wear of a discharge conduit, and occurrence of backfire when a large amount of injection is performed
​BRIEF DESCRIPTION OF THE DRAWINGS
[0009]
​FIG. 1 is a conceptual diagram (cross-sectional view) showing an example of a thermal spraying apparatus used in a thermal spraying method of the present invention;
​FORM FOR CARRYING OUT THE INVENTION
[0010]
​FIG. 1 conceptually shows an example of a thermal spraying apparatus used in a thermal spraying method of the present invention
​The thermal spraying device includes a hopper 20 as a storage means for storing the raw material powder 10, an ejector 30, and an injection means 40
[0011]
​The raw material powder 10 includes a combustible powder (for example, metal powder) and a fire-resistant powder (fire-resistant aggregate)
​The hopper 20 has a put-out port 21 for putting out the raw material powder 10 to the bottom part of the hopper 20
​The ejector 30 sucks the raw material powder 10 from the discharge port 21 by the flow of the pressurized carrier gas (oxygen gas) and mixes the carrier gas and the raw material powder 10 to form a mixture
​The injection means (injection nozzle) (40) is connected to the outlet side of the ejector (30) via a horizontal transfer pipe (50) and a rubber hose (60), and the mixture generated by the ejector (30) is injected from an injection port (nozzle hole) (41) at the tip.. The horizontal transfer pipe 50 can be omitted, and the rubber hose 60 May be directly connected to the outlet side of the ejector 30.
[0012]
​Next, the configuration of the ejector 30 will be described in detail.. The ejector 30 includes: a container part 31 having an internal space communicating with a discharge port 21 at the bottom part of the hopper 20; a tapered jet nozzle 32 for jetting the pressurized carrier gas from the tip to the internal space of the container part 31; and a discharge conduit 33 one end of which communicates with the internal space of the container part 31 and guides the mixture to the other end from the one end along the flow passage​That is, in the internal space of the container part 31, the carrier gas is jetted at a high speed toward one end (base end) of the discharge conduit 33 from a jet port (nozzle hole) at the tip of the tapered jet nozzle 32, thereby setting the internal space of the container part 31 to a negative pressure (pressure lower than atmospheric pressure).. On the other hand, a put-out port 21 of the hopper 20 is communicated with an internal space of the container part 31 through a vertical transfer pipe 70​Thus, the ejector 30 sucks the raw material powder 10 from the discharge port 21 into the internal space of the container part 31 by the flow of the pressurized carrier gas, and the carrier gas and the raw material powder 10 jetted from the jet port (nozzle hole) at the tip of the jet nozzle 32 are mixed in the internal space of the container part 31 to form a mixture
​In the ejector 30, the discharge conduit 33 consists only of a straight part having a constant cross-sectional area of the flow passage, but a throttle part and an expansion part may be provided on the inlet side and the outlet side of the straight part.
[0013]
​In this ejector 30, the internal space of the container part 31 has a throttle part 31a reducing the cross-sectional area of the flow passage of the mixture toward the discharge conduit 33 side.. A tip part (jetting port (nozzle hole)) of the jetting nozzle 32 is positioned in a space area in the throttle part 31a.. By adopting such a constitution, the ejector effect can be enhanced and mass injection can be easily realized.
[0014]
​When thermal spraying is performed by using the thermal spraying device, first, the raw material powder 10 is put out from a dispensing port 21 of the hopper 20 (a dispensing process). Next, the raw material powder 10 is introduced into a container part 31 of an ejector 30 having an internal space communicating with the discharge port 21 of the hopper 20 through a vertical transfer pipe 70 (introduction step), the raw material powder 10 guided by the introduction step is sucked by the flow of the carrier gas in the ejector 30 (suction step), and the raw material powder 10 and the carrier gas are mixed (mixing step)​Then, the mixture mixed in the mixing process is conveyed along the flow passage of the discharge conduit 33 (conveyance process), the conveyed mixture is injected by an injection means 40 (injection process), and the injected mixture is burned to form a refractory composition (formation process)
[0015]
​The thermal spraying method using such an ejector type thermal spraying device satisfies the following requirements (1-4)
​Requirement 1: The flow rate of the carrier gas is 30 (Nm3)／ H) or more and 70 (NM3)／ H) or less.
​Requirement 2: The flow velocity of the carrier gas jetted from the jet nozzle is 602 (m)／ (S) or more (1180 (M)).／ S) or less.
​Requirement 3: The flow velocity of the mixture in the flow path of the discharge conduit is 63 (m)／ (S) or more (283 (M)).／ S) or less.
​Requirement 4: The ratio of the cross-sectional area of the injection port of the injection means and the straight part of the discharge conduit (the cross-sectional area of the injection port of the injection means)／ and the cross-sectional area of the straight part of the discharge conduit is 1 or more and 4 or less.
[0016]
​In the requirement (1), the flow rate of the carrier gas is 30 (Nm3)／ H), the conveying capacity of the raw material powder is insufficient, and a large amount of injection cannot be realized.. Although the upper limit of the flow rate of the carrier gas is not particularly limited from the viewpoint of mass injection, the upper limit of the flow rate of the carrier gas is not particularly limited, but the upper limit of the flow rate of the carrier gas is not particularly limited.／ H).
​The preferable range of the flow rate of the carrier gas is 40 (Nm3)／ H) or more and 70 (NM3)／ H) or less.
​In the present invention, the "flow rate of carrier gas" refers to the flow rate of the gas ejected from the ejection nozzle.. That is, in the thermal spraying apparatus of FIG. 1, a gas (oxygen gas) having the same component as the carrier gas is introduced from a portion other than the ejection nozzle 32, for example, from the rubber hose 60, but the flow rate of the gas introduced from the portion other than the ejection nozzle 32 is not included in the "flow rate of the carrier gas".
[0017]
​In the requirement (2), the flow velocity (hereinafter, simply referred to as "carrier gas flow velocity") of the carrier gas ejected from the ejection nozzle is referred to as "carrier gas flow velocity".. Is 602 (m)／ a sufficient ejector effect cannot be obtained and a large amount of injection can not be realized.. On the other hand, the flow velocity of the carrier gas is 1180 (m)／ the flow velocity of the raw material powder is increased by increasing the flow velocity of the carrier gas, and the wear in the discharge conduit is increased.
​The preferred range of the flow velocity of the carrier gas is 699(m)／ (S) or more (1148 (M)).／ S) or less.
​The flow velocity of the carrier gas can be obtained by calculation from the cross-sectional area of the jetting port (nozzle hole) of the jetting nozzle and the flow rate of the carrier gas.
[0018]
​In the requirement (3), the flow velocity of the mixture in the flow path of the discharge conduit is 63 (m)／ a suction amount of the raw material powder by the ejector is insufficient, and a large amount of injection can not be realized.. On the other hand, the flow velocity of the mixture in the flow passage of the discharge conduit is 283 (m)／ S), wear in the discharge conduit is likely to occur.
​The preferable range of the flow velocity of the mixture in the flow path of the discharge conduit is 72 (m)／ (S) or more (172 (M)).／ S) or less.
​The flow velocity of the mixture in the flow passage of the discharge conduit can be determined by calculation from the cross-sectional area of the straight part of the discharge conduit and the flow rate of the carrier gas.
[0019]
​In the requirement 4, the ratio of the cross-sectional area of the injection port of the injection means and the straight part of the discharge conduit (the cross-sectional area of the injection port of the injection means)／ the cross-sectional area of the straight part of the discharge conduit is simply referred to as a "cross-sectional area ratio".. When the pressure is less than 1, the flow velocity of the mixture injected from the injection port of the injection means becomes too large, and the adhesion is reduced by the rebound loss.. Further, since the pressure loss at the injection port of the injection means is increased, the injection amount of the mixture is reduced, and mass injection cannot be realized.. On the other hand, when the cross-sectional area ratio is more than 4, the flow velocity of the mixture injected from the injection port of the injection means becomes too small to cause backfire.
​A preferable range of the cross-sectional area ratio is 1.4 or more and 2.3 or less
​The "cross-sectional area of the injection port of the injection means" is the opening area of the injection port, and when there are a plurality of injection ports, the total of the opening areas of all the injection ports is set.. The "cross-sectional area of the straight part of the discharge conduit" is the cross-sectional area of the straight part of the discharge conduit in a cross section orthogonal to the flow passage direction of the discharge conduit.
​In the thermal spraying device of Fig. 1, the injection port 41 of the injection means 40 and the cross section of the discharge conduit 33 (straight part) are both circular, but it is also possible to have a shape other than a circle such as an elliptical shape or a rectangular shape.. That is, even if the injection port of the injection means and the straight part of the discharge conduit are in any shape, the cross-sectional area ratio may be within a prescribed range in the requirement 4.
[0020]
​As described above, the thermal spraying method according to the present invention satisfies all of the requirements 1 to 4, so that the lowering of adhesion, the wear of the discharge conduit, and the occurrence of backfire can be suppressed when a large amount of injection is performed.
​EMBODIMENT
[0021]
​The thermal spraying test is performed under the respective thermal spraying conditions shown in Table 1 by the thermal spraying device of Fig. 1, and the injection quantity (kg)／ H), adhesion, wear of the discharge conduit, and presence/absence of backfire, and total evaluation is performed on the basis of the evaluation results.. In the thermal spraying test, a raw material powder composed of silica (SiO2) of 85 mass % and metal Si of 15 mass % as combustible powder is used as the refractory powder, and a raw material powder (mixture) is injected by flowing a carrier gas (oxygen gas) of 0.5 MPa.
​The evaluation method of each evaluation item is as follows
[0022]
​< Injection amount (kg)／ H) >
​From the weight reduction rate of the raw material powder stored in the hopper (20), the injection amount (kg)／ H).. The injection amount is 100 (kg)／ H) or more, a large amount of injection can be realized (good), and (100 kg)／ and in the case of less than H, a large amount of injection can not be realized (impossible).
[0023]
​METHOD AND DEVICE FOR TUNNEL EXCAVATION
​The adhesion rate of the raw material powder is determined from the total injection amount (kg) of the raw material powder and the rebound loss (kg) at the normal temperature, and the adhesion rate of the comparative example 1 is indexed and evaluated as 100.. Specifically, the adhesion ratio (index) is greater than 110 and not more than 100 and not more than 110, and not more than 100.
[0024]
​WEAR OF < DISCHARGE CONDUIT
​After the thermal spraying test, the abrasion state of the discharge conduit is observed visually, and the relative evaluation is performed in three stages of O, Delta and X.. That is, the wear amount of the discharge conduit is small in the order of O, Delta and X.
[0025]
​METHOD FOR DETERMINING EXISTENCE OF BACK FIRE
​The thermal spraying test is repeated 100 times, and when the occurrence of backfire is zero (good), the case of one time is Delta (), and the case of two or more times is defined as (impossible).
[0026]
​TOTAL EVALUATION >
​When all the evaluations are all ◯ (good), X is good (good), X is at least one is Delta (), and a case where there is at least one X is defined as X (impossible).

[0028]
​In Examples 1 to 7 shown in Table 1, all of the requirements 1 to 4 of the present invention satisfy all of the requirements 1 to 4 of the present invention. The evaluation of the injection amount, adhesion, wear of a discharge conduit, and the presence or absence of backfire is not × (impossible), overall evaluation is good (good) or delta (flexible), and a good result is obtained.
[0029]
​In contrast, in Comparative Example 1, in an example in which the flow rate of the carrier gas is small, the conveying capacity of the raw material powder is insufficient, and a large amount of injection cannot be achieved
[0030]
​In Comparative Example 2, a sufficient ejector effect cannot be obtained in an example in which the flow velocity of the carrier gas is low, and mass injection cannot be realized
​On the other hand, in Comparative Example 3, in an example in which the flow velocity of the carrier gas is high, the wear amount of the discharge conduit is increased
[0031]
​In Comparative Example 4, in an example in which the flow velocity of the mixture in the flow path of the discharge conduit is low, the suction amount of the raw material powder by the ejector is insufficient, and a large amount of injection cannot be achieved
​On the other hand, in Comparative Example 5, in an example in which the flow velocity of the mixture in the flow path of the discharge conduit is high, the wear amount of the discharge conduit is increased
[0032]
​In the comparative example 6, in an example in which the cross-sectional area ratio is small, the flow velocity of the mixture injected from the injection port 41 of the injection means 40 becomes too large, and the adhesion is reduced by the rebound loss.. In addition, as the pressure loss in the injection port 41 of the injection means 40 becomes large, the injection amount is reduced and a large amount of injection cannot be realized.
​On the other hand, in an example in which the cross-sectional area ratio is large in Comparative Example 7, the flow velocity of the mixture injected from the injection port 41 of the injection means 40 becomes small, and backfire is likely to occur
​DESCRIPTION OF SIGN
[0033]
​10 RAW MATERIAL POWDER
​20 HOPPER (STORAGE MEANS)
​21 PUT-OUT PORT
​30 EJECTOR
​31 CONTAINER PART
​31 A THROTTLE PART
​32 JET NOZZLE
​33 DISCHARGE CONDUIT
​40 INJECTION MEANS (INJECTION NOZZLE)
​41 INJECTION PORT (NOZZLE HOLE)
​50 HORIZONTAL TRANSFER PIPE
​50A LINING LAYER
​60 RUBBER HOSE
​70 VERTICAL TRANSFER PIPE
​RANGE OF CLAIM
​CONSTRUCTION METHOD OF TUNNEL SEGMENT
​THERMAL SPRAYING METHOD USING THERMAL SPRAYING APPARATUS FOR FORMING REFRACTORY COMPOSITION BY INJECTING AND BURNING MIXTURE OF RAW MATERIAL POWDER CONTAINING REFRACTORY POWDER AND COMBUSTIBLE POWDER AND SUPPORTING CARRIER GAS
​The injection amount of the raw material powder is 100 kg／ H or more,
​THERMAL SPRAYING DEVICE
​storage means having a put-out port for storing the raw material powder and putting out the raw material powder,
​an ejector for sucking the raw material powder from the put-out port by the flow of the pressurized carrier gas and mixing the carrier gas and the raw material powder to form the mixture,
​and an injection means for injecting the mixture generated by the ejector,
​THE EJECTOR IS PROVIDED WITH THE SAME
​CONTAINER HAVING INTERNAL SPACE COMMUNICATING WITH THE OUTLET,
​injection nozzle for jetting the pressurized carrier gas from the tip to the internal space,
​and a discharge conduit having one end communicating with the internal space and guiding the mixture to the other end from the one end along the flow path,
​The flow rate of the carrier gas is 30 (Nm3)／ H) or more,
​The flow velocity of the carrier gas jetted from the jet nozzle is 602 (m)／ (S) or more (1180 (M)).／ S) or less,
​The flow velocity of the mixture in the flow path of the discharge conduit is 63 (m)／ (S) or more (283 (M)).／ S) or less,
​The ratio of the cross-sectional area of the injection port of the injection means and the straight part of the discharge conduit (the cross-sectional area of the injection port of the injection means)／ and the cross-sectional area of the straight part of the discharge conduit is 1-4.
​CONSTRUCTION METHOD OF TUNNEL SEGMENT
​The internal space of the container part has a throttle part in which the cross-sectional area of the flow passage of the mixture decreases toward the discharge conduit side,
​The thermal spraying method according to claim 1, wherein a tip portion of the ejection nozzle is positioned in a space region in the throttle portion.
​CONSTRUCTION METHOD OF TUNNEL STRUCTURE
​The flow rate of the carrier gas is 40 (Nm3)／ H) or more and 70 (NM3)／ H) or less.
​The flow velocity of the carrier gas is 699(m)／ (S) or more (1148 (M)).／ S) or less,
​The flow velocity of the mixture in the flow path of the discharge conduit is 72 (m)／ (S) or more (172 (M)).／ S) or less,
​The ratio of the cross-sectional area of the injection port of the injection means and the straight part of the discharge conduit (the cross-sectional area of the injection port of the injection means)／ The thermal spraying method according to claim 1 or 2, wherein a cross-sectional area of the straight portion of the discharge conduit is 1.4 or more and 2.3 or less.