TWI761883B - Safety structure and repairing method of waste acid recovery roaster - Google Patents

Abstract

The invention relates to a waste acid recovery roasting furnace safety structure and repairing method. The furnace body is formed into a layer-by-layer combination structure, wherein the roasting furnace safety structure includes: a furnace bottom, a furnace middle layer and a furnace top, etc. , By combining the furnace bottom, furnace middle layer and furnace top with different furnace wall thicknesses, a roaster with low cost, light weight, and safe operation of the overall structure of the furnace body is produced; and the roaster can be repaired safely. The construction method includes: a furnace body detection step, a repairing plate removal step, a welding and bonding step, etc. By means of the safe repairing method, the service life of the roasting furnace can be prolonged by a low-cost repairing method.

Description

Safety structure and repairing method of waste acid recovery roaster

The invention belongs to the technical field of waste acid regeneration by a spray roasting method, in particular to a roasting furnace safety structure and a repairing method.

Generally speaking, after the waste mixed acid discharged from the pickling line in the stainless steel process is filtered, pre-concentrated and pressurized, it will be sprayed into the furnace from the spray gun 91 at the top of the conventional roasting furnace 9, as shown in Figure 5; and Several burners 92 are arranged around the middle section of the furnace body to spray and burn the acid mist in the furnace, so that the temperature of the furnace top 93 is about 303°C, the temperature of 94 at the middle section of the furnace is about 634°C, and the temperature of the furnace bottom 95 is about 363°C, and The overall negative pressure in the furnace is controlled to -0.4kpa, so that the vaporized water and free acid generated by the spray roasting of the waste mixed acid in the conventional roasting furnace 9 will be discharged from the channel of the furnace top 93, and the reaction chemical formula in the furnace is as follows: As shown in [Chem. 1] and [Chem. 2], the metal oxides produced by the roasting are transported to the discharge port of the furnace bottom 95 for discharge, and both of them can be recycled and reused after being treated separately.

[Chemical 1]H ₂ O(l)>H ₂ O(g) HNO ₃ (aq)>HNO ₃ (g) HF(aq)>HF(g)

[Chemical 2] 2FeF ₃ -3H ₂ O>Fe ₂ O ₃ +6HF 2HNO ₃ >NO ₂ +NO+O ₂ -H ₂ O NO ₂ >NO+1/2O ₂

The furnace body steel plate of the existing conventional roasting furnace 9 is welded by 20mm thick 1.4876 high-nickel stainless steel (that is, Incoloy 800) plate, which is a roasting furnace with uniform furnace wall thickness, but after several years of use, it is found in the furnace bottom. A large amount of iron oxide powder was observed outside 95. When the furnace was stopped to inspect the furnace top 93, the furnace middle 94, and the furnace bottom 95, it was found that the turning point 96 between the furnace middle 94 and the furnace bottom 95 became thinner and formed a stress corrosion phenomenon. , resulting in cracking and affecting use.

Analysis of the main reason for the corrosion and thinning of the roasting furnace body is that most of the iron oxide powder generated by roasting the waste mixed acid stays in the furnace bottom 95 for a long time. It has not been completely evaporated, so that these iron oxide powders on the furnace bottom 95 still have fluorine ions remaining, and under high temperature conditions, a synergistic effect is caused, and the steel plate on the furnace bottom 95 is further rapidly corroded.

Therefore, it is necessary to carry out warranty and structural improvement on the existing conventional roasting furnace, and the existing conventional roasting furnace has the following problems: (1) the furnace body is easily thinned quickly, (2) the furnace body is not easy to repair, (3) it is difficult to Prediction and maintenance, (4) the overall replacement cost is too high, and (5) it is difficult to combine different materials.

For this reason, in view of the problems existing in the above-mentioned conventional roaster, the inventor has developed a kind of waste acid recovery roaster safety structure and repair method, so the main purpose of the present invention is to provide a lightweight, low-cost and a durable safety structure of a waste acid recovery roaster; the secondary purpose of the present invention is to provide a waste acid recovery roaster safety repair method with low cost, prolonging the service life of the roaster and taking into account safety.

In order to achieve the above-mentioned purpose, the present invention utilizes the following technical means: about the safety structure of the waste acid recovery roaster of the present invention, the system includes: a furnace bottom, which is made of heat-resistant and corrosion-resistant steel and further includes a bottom plate and a wall plate, and The bottom plate and the wall plate form a turning point, and an inner lining ring is connected at the turning point, and the outer diameter of the bottom circumference formed by the inner lining ring is smaller than the outer diameter of the top circumference formed by the inner lining ring. The bottom circumference of the ring is connected to the bottom plate, and the top circumference of the inner lining ring is connected to the wall plate, and the inner lining ring and the bottom plate are made of different materials, and the inner lining ring and the wall plate are made of different materials Material; a furnace middle layer, which is made of heat-resistant and corrosion-resistant steel, and the furnace middle layer is bonded above the furnace bottom; and a furnace top, which is made of heat-resistant and corrosion-resistant steel, and the furnace top is made of heat-resistant and corrosion-resistant steel. It is combined at the top of the middle layer of the furnace; the furnace bottom, the middle layer and the furnace top are made of materials with different corrosion resistance properties to produce a roasting furnace that strengthens the overall structural safety of the furnace body.

The furnace bottom, furnace middle layer and furnace top are set to have the same wall thickness.

The furnace bottom has a first wall thickness (t1), the furnace middle layer has a third wall thickness (t3), and the furnace top has a fourth wall thickness (t4), and t1>t3>t4.

The described furnace bottom further comprises an upper furnace bottom layer and a furnace bottom lower layer, wherein the furnace bottom upper layer is combined with the upper part of the furnace bottom lower layer, and the furnace bottom upper layer and the furnace bottom lower layer are set to different outer diameters; The upper layer of the furnace bottom further includes the bottom plate and the wall plate, and the lower layer of the furnace bottom and the bottom plate are provided with the first wall thickness (t1), and the wall plate and the inner lining ring are both set to have the first wall thickness (t1). The second wall thickness (t2), again t1>t2>t3>t4.

There is another tube channel connected to the furnace hood layer of the furnace roof, and the tube channel is made of heat-resistant and corrosion-resistant steel with a fifth wall thickness (t5), and t1>t2>t3>t4>t5.

Among them, according to the test data of 2.5 to 3 years, in the area where the wall thickness becomes thinner than at least half, several pieces of heat-resistant and corrosion-resistant steel repair plates are welded and combined.

The heat-resistant and corrosion-resistant steel material is inconel 316L, inconel 625 or inconel 800, the first wall thickness (t1) is set to 20mm, and the second wall thickness (t2) is set to 14 mm, the third thickness (t3) is 12 mm, the fourth thickness (t4) is 10 mm, and the fifth thickness (t5) is 8 mm.

Regarding the safe repairing method of the waste acid recovery roaster according to the present invention, it includes: a furnace body detection step, which is an area where the wall thickness of the roaster becomes thinner by at least half or more by observation or instrument measurement; The repairing plate step is to take several repair plates of heat-resistant and corrosion-resistant steel, and the repair plate is of the same material as the original furnace; and a welding combination step is to weld the repair plates and fill them in the thinned area of the furnace wall ; Through the above steps, a low-cost repair method is provided to prolong the service life of the roasting furnace.

The waste acid recovery and roasting furnace safety repair method further includes a weld bead detection step, wherein the weld bead detection step uses penetrant inspection to detect all the weld beads in the welding bonding step.

The length and width of the repairing plate are set as 900mm*900mm, and the material of the repairing plate is inconel 316L, inconel 625 or inconel 800.

By the above-mentioned technical means, the present invention can achieve the following effects:

1. The safety structure of the roasting furnace body of the present invention is composed of furnace bottoms, furnace middle layers and furnace tops with different wall thicknesses, and relatively thin steel materials are used in the parts that are not easy to corrode, and relatively thick steel materials are used in the parts that are easy to corrode, A lining ring is used to protect the turning point of the furnace bottom, so that it cannot form stress corrosion, so as to provide a low-cost, lightweight, and safe operation of the overall structure of the furnace body to meet the regulatory requirements.

2. The roasting furnace safety repair method of the present invention provides observation of the negative pressure change of the exhaust gas exhaust fan, which can quickly detect the thinned part of the furnace body, and use several heat-resistant and corrosion-resistant plates to partially repair the roasting furnace by welding to maintain the furnace body as a whole. The structure operates safely to comply with regulatory requirements to avoid the overall replacement of the roaster and greatly reduce maintenance costs.

3. The present invention provides a roasting furnace safety structure that takes into account structural safety and light weight, uses relatively thin steel in the parts that are not easy to corrode, and uses relatively thick steel in the parts that are easy to corrode, and provides the safe repairing method of the roasting furnace of the present invention. The simple method of periodically repairing the furnace body can prolong the service life of the roasting furnace many times, and at the same time save material resources and have environmental protection performance.

A: Roaster safety structure

B: Roaster safety repair method

a: furnace body detection steps

b: step of taking the repair plate

c: Welding and bonding step

d: Weld bead detection steps

1: furnace bottom

11: Bottom of the furnace

110: The turning point

12: Upper floor of furnace bottom

121: Bottom plate

122: Siding

13: Liner ring

2: Furnace middle layer

3: Stove top

31: Furnace hood

32: Stove top middle layer

33: Lower Stove Top

4: Tube channel

5: Thinned area

6: Repair the sheet

7: Weld bead

9: Xi-style roaster

91: Airbrush

92: Burner

93: Stove top

94: Middle section of furnace

95: Furnace Bottom

96: Turning Point

Figure 1: is a three-dimensional appearance view of the safety structure of the waste acid recovery roaster of the present invention.

Figure 2: is a sectional view of the safety structure of the waste acid recovery roaster of the present invention.

Fig. 3: It is a flow chart of the steps of the safe repairing method of the waste acid recovery roaster of the present invention.

FIG. 4 is a schematic diagram of the implementation of the safe repairing method of the waste acid recovery roaster according to the present invention.

Figure 5: is a schematic diagram of a conventional roaster.

First of all, please refer to FIG. 1 and FIG. 2 , the present invention relates to a safety structure A of a waste acid recovery and roasting furnace, which is a welded joint structure in which the furnace body is stacked layer by layer, and the materials of each layer of the furnace body can be selected from the same material. Or different materials, can also have the same wall thickness or different wall thickness, in response to different properties of acid recovery, wherein the roaster safety structure A system includes: a furnace bottom 1, a furnace middle layer 2, a furnace top 3 or As shown in Figure 2, the furnace bottom 1 is defined as the h1 section, the furnace middle layer 2 is defined as the h2 section, the furnace top 3 is defined as the h3 section, and the tube channel 4 is connected to the Above the furnace roof 3, several embodiments are described as follows.

Regarding the first embodiment of the safety structure A of the roasting furnace of the present invention, the furnace bottom 1, the furnace middle layer 2 and the furnace top 3 are made of the same material and combined with each other, and heat-resistant and corrosion-resistant steel materials are selected, and the furnace The bottom 1, the furnace middle layer 2 and the furnace top 3 can be set to the same wall thickness, and in a preferred embodiment, the wall thickness of the furnace bottom 1 is greater than the wall thickness of the furnace middle layer 2 and the furnace top 3; A bottom plate 121 and a wall plate 122 provided on the furnace bottom 1 form a turning point 110 , and an inner lining ring 13 is connected to the turning point 110 , and the bottom circumference of the inner lining ring 13 is connected to the bottom plate 121 , and the top circumference of the inner lining ring 13 is connected to the wall plate 122, and the inner lining ring 13 and the bottom plate 121 are made of different materials, and the outer diameter of the bottom circumference is smaller than the outer diameter of the top circumference, and the inner lining Ring 13 with siding 122 is set as a different material to produce a roasting furnace that strengthens the overall structural safety of the furnace body; in particular, the aforementioned heat-resistant and corrosion-resistant steels are selected from inconel 316L, inconel 625 or inconel 800 with high corrosion resistance. Steel plate material.

Regarding the second embodiment of the safety structure A of the roasting furnace of the present invention, the second embodiment has the same furnace body structure as the first embodiment, and the difference between the two is that the second embodiment is the furnace bottom 1, the furnace The middle layer 2 and the furnace top 3 are made of materials with different corrosion resistance properties, and inconel 316L, inconel 625 or inconel 800 with high corrosion resistance are selected. Inconel 316L, inconel 625 or inconel 800, etc. Arranged, the inconel 625 is better than the inconel 800, the inconel 800 is better than the inconel 316L.

Regarding the third embodiment of the safety structure A of the roasting furnace of the present invention, the furnace bottom 1, the furnace middle layer 2 and the furnace top 3 are set to different wall thicknesses; The furnace bottom 1 further comprises an upper furnace bottom layer 12 and a furnace bottom lower layer 11, wherein the furnace bottom upper layer 12 is welded and bonded to the top of the furnace bottom lower layer 11 and the furnace bottom upper layer 12 and the furnace bottom lower layer 11 are set to have unequal diameters.

In addition, the upper layer 12 of the furnace bottom further includes a turning point 110, a bottom plate 121 and a wall plate 122, and the turning point 110 is formed by combining the bottom plate 121 and the wall plate 122, and a turning point 110 is connected with a The inner lining ring 13, and the outer diameter of the bottom circumference formed by the inner lining ring 13 is smaller than the outer diameter of the top circumference formed by the inner lining ring 13, and the inner lining ring 13 is also made of heat-resistant and corrosion-resistant steel, and has the function of protecting the turning The function of the position 110 is to prevent the turning point 110 from being damaged due to stress corrosion caused by contacting the acid medium; further, the lower layer 11 of the furnace bottom and the bottom plate 121 are provided with a first wall thickness (t1), and the wall plate 122 and the The inner lining rings 13 are all set to have a second wall thickness (t2), and the second wall thickness (t2) is between the first wall thickness (t1) and the third wall thickness (t3).

The furnace intermediate layer 2 is made of heat-resistant and corrosion-resistant steel material with a third wall thickness (t3), and the furnace intermediate layer 2 is welded to the top of the furnace bottom 1, and the third wall thickness (t3) is smaller than the first wall thickness (t1) of the furnace bottom 1 .

The furnace roof 3 is made of heat-resistant and corrosion-resistant steel with a fourth wall thickness (t4), and the furnace roof 3 is welded to the upper part of the furnace middle layer 2, and the fourth wall thickness (t4) ) is less than the third wall thickness (t3) of the furnace middle layer 2; further, the furnace roof 3 further comprises a furnace hood layer 31, a furnace roof middle layer 32 and a furnace roof lower layer 33, wherein the furnace hood layer 31 is welded and combined Above the furnace top middle layer 32 , and the furnace top middle layer 32 is welded to the top of the furnace top lower layer 33 .

The pipe channel 4 is welded to the furnace hood layer 31 of the furnace roof 3, and is used as a channel for the vaporized water and free acid produced by spray roasting, and the pipe channel 4 has a fifth wall thickness (t5). It is made of heat-resistant and corrosion-resistant steel, and the fifth wall thickness (t5) is smaller than the fourth wall thickness (t4).

In view of the fact that the lower part of the roasting furnace is easy to be corroded and damaged, the safety structure A of the roasting furnace of the present invention mainly combines the furnace bottom 1, the furnace middle layer 2, the furnace top 3 or/and the pipe channel 4 with different furnace wall thicknesses by welding. , and in particular, the thickness of the roasting furnace of the present invention is decreased from bottom to top (t1>t2>t3>t4>t5), so as to produce a roasting furnace with low cost, light weight, and taking into account the safe operation of the overall structure of the furnace body; wherein In addition, the above-mentioned heat-resistant and corrosion-resistant steel materials are preferably selected from inconel 316L, inconel 625 or inconel 800 with high corrosion resistance. The wall thickness (t1) is preferably set to 20mm, the second wall thickness (t2) is preferably set to 14mm, the third wall thickness (t3) is preferably set to 12mm, and the fourth wall thickness (t4) It is preferably set to 10mm, and the fifth wall thickness (t5) is preferably set to 8mm.

Please refer to FIG. 3 and FIG. 4 , regarding the waste acid recovery roasting furnace safety repair method B of the present invention, it mainly provides repairing to the thinned area 5 of the furnace wall of the roasting furnace, so as to avoid the overall replacement of the roasting furnace, which includes : a furnace body detection step a, a repair plate removal step b, a welding combination step c or/and a weld bead detection step d.

The furnace body detection step a is to observe or measure the area where the wall thickness of the roasting furnace becomes thinner by at least half; wherein the observation method is to observe that the operating power of the exhaust gas exhaust fan is increased, from 82% to 90%, And a large amount of iron oxide powder was observed outside the furnace bottom 1; while the instrument measurement type stopped the furnace and checked the wall thickness of the furnace top 3, the furnace middle layer 2 and the furnace bottom 1 with an ultrasonic thickness gauge .

The step b of taking the repairing plate is to take several repairing plates 6 of heat-resistant and corrosion-resistant steel, and the repairing plate 6 is preferably the same as the material of the original furnace; further, the length and width of the repairing plate 6 are set as 900mm*900mm , and it is carried into the furnace from the furnace door and then attached and welded, and the material of the repair plate 6 is inconel 316L, inconel 625 or inconel 800 and other British high nickel alloy materials.

The welding and combining step c are to weld and fill the several repairing plates 6 and arrange them in the thinned area 5 of the furnace wall, as shown in FIG. 4.0mm nickel-based electrode; in other words, fill the weld bead 7 around and in the gaps of the repaired plates 6; in particular, the thinned area 5 of the furnace wall may be a partial part of the entire furnace wall or the furnace body.

The weld bead detection step d uses a non-destructive penetrant testing method (Penetrant Testing, referred to as PT) to detect all the weld beads 7 in the welding combination step c to ensure the safety of the repaired part.

By the above-mentioned steps, the service life of the roaster is extended by a low-cost, cyclical repair method, so as to reduce the maintenance cost of the roasting equipment, save resource materials and environmental protection requirements; further, the roaster safety structure A of the present invention is actually put into production And the test lasted for three years. After nearly two years (time T ~ time T2), the wall thickness of the furnace body was measured with an ultrasonic thickness gauge every one and a half months, and the following table 2 and table 3 were obtained. The wall thickness measurement data shown (unit: mm), in which Table 3 is a continuation of Table 2 and adds (3.1), (4.1), (4.2), (5.1), (5.2) The furnace body part wall thickness detection position, and the oblique lines in Table 2 and Table 3 represent that the furnace body part does not need to be measured.

Through the above-mentioned Table 2 and Table 3, it can be known that the roasting furnace of the present invention in the production test operation is corroded and thinned faster at the base plate 121, the lining ring 13 and other parts, and the operation is used for about 2 years (time T ~ time). T2), let the bottom plate 121 be left by 0.5mm from the original thickness of 20mm, and the lining ring 13 can be left by 3mm from the original thickness of 14mm, so the roasting furnace safety repair method B of the present invention can be used for parts such as the bottom plate 121, the inner lining ring 13, etc. Several pieces of repairing plates 6 made of inconel 625 are welded and repaired until the bottom plate 121 is repaired, and the thickness of the inner lining ring 13 is restored to 10.8mm. The thickness of the inner lining ring 13 is still 10mm and the thickness of the inner lining ring 13 is still 10mm. Therefore, the periodic use of the roaster safety repair method B of the present invention can indeed prolong the service life of the roaster many times and avoid replacing the entire roaster.

In the same way, the wall thickness detection item (3.1) of the roasting furnace of the present invention, that is, the middle layer 32 of the furnace top 10 cm away from the lower weld bead is also easy to become thinner, and the test operation is used for about 2.5 years (time T ~ time T8). The position is left by 5mm from the original 10mm, so at this time, the roaster safety repair method B of the present invention can be used for repairing. In other words, the roaster safety repair method B of the present invention is not only applicable to the roaster of the present invention, but also applicable to other conventional roasting. Furnace repair; through the above-mentioned Table 2 and Table 3, it can be known that the turning point 110 of the furnace bottom 1 has been used and operated for 3 years (time T ~ time T9), and there is no cracking and damage due to stress corrosion, so this The structure of the inner lining ring 13 of the inventive roaster does indeed protect the turning point 110 .

Moreover, after repairing the part of the furnace bottom 1 where the furnace bottom 1 is thinned by using the repairing plate 6 made of inconel 625 material, it is restored to a thickness of 10.7 mm by the safe repairing method B of the roasting furnace of the present invention. After more than 1 year (time T3～time T9), this thickness still has 10.4mm, it can be known that the position after repairing by the roaster safety repairing method B of the present invention, the speed of its corrosion and thinning is slower than the original, so the roaster of the present invention is slower than before. Safe Repair Method B is the best simple method for repairing roasters in the industry.

Therefore, the roasting furnace of the present invention is actually put into production, and through the three-year test (time T ~ time T9), it can be found that the speed of corrosion and thinning of the bottom 1 of the roasting furnace is relatively fast, followed by the top 3 of the furnace, and the middle of the furnace The layer 2 is hardly affected by acid corrosion, so the third embodiment of the present invention uses furnace layers of different materials and thicknesses, and the structure of disposing the lining ring 13 at the turning point 110 in the furnace can be used as reinforcement. The best solution for the safety of the furnace body structure of the roaster.

A: Roaster safety structure

1: furnace bottom

11: Bottom of the furnace

110: The turning point

12: Upper floor of furnace bottom

2: Furnace middle layer

3: Stove top

31: Furnace hood

32: Stove top middle layer

33: Lower Stove Top

Claims (9)

A safety structure of a waste acid recovery roasting furnace includes: a furnace bottom, which is made of heat-resistant and corrosion-resistant steel and further includes a bottom plate and a wall plate, and the bottom plate and the wall plate form a turning point, and in the An inner lining ring is connected at the turning point, and the outer diameter of a bottom circumference formed by the inner lining ring is smaller than the outer diameter of a top circumference formed by the inner lining ring, wherein the bottom circumference of the inner lining ring is connected to the bottom plate, and the inner lining ring The top circumference is connected to the wall plate, and the inner lining ring and the bottom plate are made of different materials, and the inner lining ring and the wall plate are made of different materials; a furnace middle layer is made of heat-resistant and corrosion-resistant steel , and the furnace middle layer is bonded above the furnace bottom; and a furnace top is made of heat-resistant and corrosion-resistant steel, and the furnace top is bonded above the furnace middle layer; by the furnace bottom , The middle layer of the furnace, and the top of the furnace are set to be a combination of materials with different corrosion resistance properties, so as to make a roasting furnace that strengthens the overall structure of the furnace body. The waste acid recovery roaster safety structure according to claim 1, wherein the furnace bottom, furnace middle layer, and furnace top are set to the same wall thickness. The safety structure of the waste acid recovery roaster according to claim 1, wherein the furnace bottom has a first wall thickness (t1), the furnace middle layer has a third wall thickness (t3), and the furnace top has a fourth wall thickness (t4), and t1>t3>t4. The waste acid recovery roasting furnace safety structure according to claim 3, wherein the furnace bottom further comprises an upper furnace bottom layer and a furnace bottom lower layer, wherein the furnace bottom upper layer is combined with the upper part of the furnace bottom lower layer, and the furnace bottom upper layer , The lower layer of the furnace bottom is set to be different in outer diameter; and the upper layer of the furnace bottom further includes the bottom plate and the wall plate, and the bottom layer of the furnace bottom and the bottom plate are provided with the first wall thickness (t1), and the wall Both the plate and the lining ring are set to have a second wall thickness (t2), and t1>t2>t3>t4. The waste acid recovery roaster safety structure according to claim 4, wherein another pipe channel is connected to the furnace hood layer of the furnace top, and the pipe channel is made of heat-resistant and corrosion-resistant steel with a fifth wall thickness (t5). Then, t1>t2>t3>t4>t5. According to the safety structure of the waste acid recovery roaster according to claim 1, according to the test operation data of 2.5 to 3 years, several pieces of heat-resistant and corrosion-resistant steel repair plates are used for welding and bonding in the area where the wall thickness becomes thinner by at least half. The safety structure of the waste acid recovery roaster according to any one of claim 1 to claim 6, wherein the heat-resistant and corrosion-resistant steel material is set as inconel 316L, inconel 625 or inconel 800, and the first wall thickness (t1) The second wall thickness (t2) is set to 14mm, the third wall thickness (t3) is set to 12mm, the fourth wall thickness (t4) is set to 10mm, and the fifth wall thickness (t5) is set to 8mm. A waste acid recovery roasting furnace safety repair method includes: a furnace body detection step, which is based on observing the negative pressure change of the exhaust gas exhaust fan to know the area where the wall thickness of the roasting furnace becomes thinner by at least half; Take several repair plates of heat-resistant and corrosion-resistant steel, and the repair plates are of the same material as the original furnace; a welding and bonding step is to weld the repair plates and fill them in the thinned area of the furnace wall; and a weld bead inspection step, wherein the weld bead detection step is to detect all the weld bead in the welding bonding step by penetrant inspection method; through the above-mentioned steps, a low-cost repair method is provided to prolong the service life of the baking furnace. The safe repairing method for waste acid recovery roaster according to claim 8, wherein the length and width of the repairing plate are set to 900mm*900mm, and the material of the repairing plate is inconel 316L, inconel 625 or inconel 800.

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