CN114370762A - Continuous heating furnace - Google Patents

Continuous heating furnace Download PDF

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Publication number
CN114370762A
CN114370762A CN202011096522.8A CN202011096522A CN114370762A CN 114370762 A CN114370762 A CN 114370762A CN 202011096522 A CN202011096522 A CN 202011096522A CN 114370762 A CN114370762 A CN 114370762A
Authority
CN
China
Prior art keywords
continuous heating
heating furnace
heat
furnace
heat generation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202011096522.8A
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Chinese (zh)
Inventor
岩田晃和
青木道朗
松井良太
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ngk Technocera Suzhou Co ltd
Original Assignee
Ngk Technocera Suzhou Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ngk Technocera Suzhou Co ltd filed Critical Ngk Technocera Suzhou Co ltd
Priority to CN202011096522.8A priority Critical patent/CN114370762A/en
Publication of CN114370762A publication Critical patent/CN114370762A/en
Pending legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/06—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated
    • F27B9/062—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated electrically heated
    • F27B9/063—Resistor heating, e.g. with resistors also emitting IR rays
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B9/36—Arrangements of heating devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B9/36—Arrangements of heating devices
    • F27B2009/3638—Heaters located above and under the track

Abstract

The present invention provides a continuous heating furnace (1), characterized by comprising: a plurality of rod-shaped, tubular or spiral-tubular upper heating elements (2) disposed above a conveyance path (12) in the furnace (11) and arranged in parallel so as to penetrate through both left and right side walls (14, 15) of the continuous heating furnace; and a protection tube (3) covering the upper heating element. According to the continuous heating furnace of the present invention, since the protective tube covering the upper heating element is provided, the upper heating element can be prevented from being corroded by a substance derived from the object to be treated during the heating treatment.

Description

Continuous heating furnace
Technical Field
The invention relates to a continuous heating furnace.
Background
Conventionally, for example, a continuous heating furnace such as a roller kiln for heat treatment of a lithium ion battery positive electrode material is known. Such a continuous heating furnace generally includes, as shown in fig. 5: a conveying path formed by a rotating roller; and a plurality of rod-shaped, tubular, or spiral-tubular upper heating elements 102 disposed above the conveyance path and arranged in parallel so as to penetrate through the left and right side walls 114, 115 of the continuous heating furnace. The left and right side walls 114, 115 are opened with through holes 116, and the through holes 116 have an inner diameter larger than the outer diameter of the upper heating element 102, and the upper heating element 102 is inserted therein.
The gap between the through hole 116 and the upper heating element 102 is filled with a fibrous ceramic block-shaped sealing material 117 to prevent heat leakage. The upper heating element 102 includes: a high heat generation portion 102a having a high resistance value and contributing to heat generation; and a low heat generation part 102b having a low resistance value, the high heat generation part 102a being disposed at the center of the upper heat generation body 102, the low heat generation part 102b being disposed at both ends thereof.
In the upper heat-generating body 102, the high heat-generating portion 102a has a length of H-d 1X 12. Where H is an effective heating width in the furnace, and d1 is a length from a boundary between the high heat generating portion 102a and the low heat generating portion 102b to the inner surface of the side walls 114 and 115. In general, if the high heat generating portions 102a are present in the vicinity of the side walls 114, 115, the life of the upper heat generating element 102 may be shortened by overheating, and therefore d1 is adjusted to 30 to 50 mm.
In such a conventional continuous heating furnace, substances derived from the object to be treated may corrode the upper heating element during the heating treatment. Further, since the upper heater is corroded, a part of the upper heater may fall off to contaminate the object to be processed, and particularly, in the case of processing the object to be processed at a high temperature, there is a high risk.
In addition, as shown in fig. 6, in the conventional continuous heating furnace, since the difference between the temperature at the center in the width direction and the temperature near the side wall is large in the upper temperature distribution ta and the lower temperature distribution tb in the furnace, it is sometimes difficult to ensure the uniformity of the product quality of the object to be processed.
Disclosure of Invention
(problems to be solved by the invention)
The invention aims to provide a continuous heating furnace, which can prevent an upper heating body from being corroded by a substance from a processed object during heating processing. Further, it is an object to provide a continuous heating furnace capable of making the temperature distribution in the width direction in the furnace more uniform.
(means for solving the problems)
In order to solve the above problem, a continuous heating furnace according to a first aspect of the present invention includes: a plurality of rod-shaped, tubular or spiral-tubular upper heating elements disposed above the conveying path in the furnace and arranged in parallel to penetrate through both left and right side walls of the continuous heating furnace; and a protection tube covering the upper heating element.
In a second aspect of the present invention, in the continuous heating furnace of the first aspect,
the upper heating element includes: a central low-heating portion formed in the central portion; and high heat generating portions formed integrally with the central low heat generating portion on both sides of the central low heat generating portion.
A third aspect of the present invention is characterized in that, in the continuous heating furnace of the second aspect,
the ratio of the central low heat generation part of the upper heat generation body is 10% to 70% of an effective heating width in the furnace.
A fourth aspect of the present invention is characterized in that, in the continuous heating furnace of the second aspect,
the plurality of upper heating elements includes: a first upper heat-generating body in which the central low heat-generating portion is short in length; and a second upper heat generating element in which the length of the central low heat generating portion is longer than that of the first heat generating element.
A fifth aspect of the present invention is the continuous heating furnace of the fourth aspect,
the difference in length between the central low heat generation portions of the upper heat generation elements adjacent in the front-rear direction of the conveyance path is 10% to 90% of the effective heating width in the furnace.
A sixth aspect of the present invention is characterized in that, in the continuous heating furnace of the fourth aspect,
the upper heat generating element further includes a third upper heat generating element having the high heat generating portion in a central portion thereof without the central low heat generating portion.
A seventh aspect of the present invention is characterized in that, in the continuous heating furnace of the first aspect,
the disclosed device is provided with: and a plurality of rod-shaped or tubular lower heating elements disposed below the conveying path in the furnace, and arranged in parallel to penetrate through both left and right side walls of the continuous heating furnace.
An eighth aspect of the present invention is characterized in that, in the continuous heating furnace of the first aspect,
the protection tube is a mullite tube, an alumina tube or a quartz tube.
The ninth aspect of the present invention is characterized in that, in the continuous heating furnace of the second aspect,
the high-heating part extends to the inside of the left side wall and the right side wall.
(effect of the invention)
According to the continuous heating furnace of the present invention, since the protective tube covering the upper heating element is provided, the upper heating element can be prevented from being corroded by a substance derived from the object to be treated during the heating treatment.
Drawings
Fig. 1 is a sectional view of a continuous heating furnace according to the present invention.
Fig. 2 is a diagram in which three types of modes are arranged in a horizontal cross section of the furnace for explaining the structure of the vicinity of the upper heating element of the continuous heating furnace according to the present invention.
Fig. 3 is a diagram illustrating a temperature distribution in the furnace of the continuous heating furnace according to the present invention.
Fig. 4 is a cross-sectional view of the vicinity of the upper heating element for explaining the structure of the upper heating element in which the high-temperature heating element extends to the inside of both left and right side walls of the furnace body.
FIG. 5 is a sectional view for explaining the structure of the vicinity of the upper heating element of the continuous heating furnace of the conventional example.
Fig. 6 is a diagram illustrating a temperature distribution in the furnace of the continuous heating furnace of the conventional example.
Description of the symbols
Roller kiln (continuous heating furnace)
2 Upper heating element
2a high heat generation part
2b Low heat generation part
2c central low heat generating part
3 protective tube
5 lower heating element
11 furnace inside
12 conveying path
14 left side wall
15 right side wall
16 through hole
17 sealing material
21 first upper heating element
22 second upper heating element
23 third upper heating element
24 fourth upper heating element
S sagger
Detailed Description
The continuous heating furnace according to the present invention will be described by taking the roller kiln 1 as an example. The roller kiln 1 is a device that performs heat treatment of an object to be treated while conveying a sagger S filled with the object to be treated. Examples of the object to be treated include a positive electrode material and a negative electrode material of a lithium ion battery.
The furnace body of the roller kiln 1 includes a top wall 18, a bottom wall 19, and both side walls 14 and 15, and is a heat insulating structure formed in a substantially rectangular parallelepiped shape. The furnace body has: a processing space as an internal space; and an inlet for introducing the sagger S into the furnace body and an outlet for discharging the sagger S out of the furnace body. Further, the roller kiln 1 includes: a temperature raising region for raising the temperature of the furnace 11; a firing temperature zone disposed on the downstream side in the conveyance direction of the temperature rise zone and configured to maintain the temperature in the furnace 11 at a substantially constant temperature; and a cooling region disposed on the downstream side in the transport direction of the firing temperature region.
The roller kiln 1 is divided into a plurality of chambers by forming an upper partition wall which is located above the furnace interior 11 and has a height equal to or greater than the height of the sagger S from the conveyance path, and a lower partition wall which is located below the furnace interior 11 and has an upper end located at a height not in contact with the roller conveyance path. By this division, temperature interference between chambers and control of gas flow in the furnace can be performed. The material of the upper partition wall and the lower partition wall 2 is not particularly limited, and may be selected in consideration of heat resistance, and may be formed using, for example, a refractory brick or a heat-resistant fiber ceramic plate.
As shown in fig. 1, the roller kiln 1 includes: a plurality of rod-like, tubular or spiral-tubular upper heating elements 2 disposed above the conveyance path 12 in the furnace 11 and arranged in parallel so as to penetrate through the left and right side walls 14, 15 of the roller kiln; and a protection tube 3 covering the upper heating element 2.
The roller kiln 1 further includes: a plurality of rod-like, tubular, or spiral-tubular rod-like or tubular lower heating elements 5 disposed below the conveyance path 12 in the furnace 11 and penetrating through both left and right side walls 14, 15 of the roller kiln. In the present embodiment, the lower heating element 5 is not covered with the protective tube 3, but the lower heating element 5 may be covered with the protective tube 3. The left and right side walls 14, 15 are opened with through holes 16, and the through holes 16 have an inner diameter larger than the outer diameter of the protection pipe 3, and the protection pipe 3 is inserted therein. The gap between the protection tube 3 and the upper heating element 2 is filled with a fiber ceramic block-shaped sealing material 17 to prevent heat leakage.
The conveying path 12 is constituted by a plurality of conveying rollers, and these conveying rollers are rotated by a driving device, not shown, to convey the sagger S. The roller kiln 1 includes: a temperature sensor for detecting the temperature of the furnace interior 11; and a temperature control device for controlling the temperature of the furnace interior 11 by controlling the upper heating element 2 and the lower heating element 5 based on the temperature detected by the temperature sensor.
As shown in fig. 2, in the present embodiment, an example in which three types of upper heating elements 21, 22, and 23 are arranged from the upstream side to the downstream side in the conveyance direction D as the upper heating element 2 is shown. The first upper heating element 21 and the second upper heating element 22 have: a central low-heat generation portion 2c formed in the central portion; and high heat generation portions 2a formed integrally with the central low heat generation portion 2c on both sides of the central low heat generation portion 2 c. As the third upper heat-generating body 23, similarly to the upper heat-generating body 102 of the conventional example, a heat-generating body having no central low heat-generating portion 2c in the central portion and having a high heat-generating portion 2a in the central portion is used. The both end portions of the upper heat-generating elements 23, 21, 22 are provided with the low heat-generating portions 2b, similarly to the upper heat-generating element 102 of the conventional example. The lower heating element 5 can have the same configuration as the first upper heating element 21, the second upper heating element 22, and the third upper heating element 23.
The upper heating element 2 and the lower heating element 5 are used to heat the atmosphere of the object to be processed and the processing space in the sagger S passing through the furnace 11, and are configured as ceramic heaters such as SiC heaters, for example.
When the upper heating element 2 is formed using SiC, for example, the resistance value can be reduced by immersing the central portion with metal silicon. The low-heat generation portion 2b and the central low-heat generation portion 2c, which generate heat when energized, are formed in this manner, and the high-heat generation portion 2a, which generates heat by energization, is formed without dipping metal silicon on both sides of the central low-heat generation portion 2c to increase the resistance value. In the present invention, the low-heat generation portions 2b and the central low-heat generation portion 2c mean portions having a resistivity of about 20% or less of that of the low-heat generation portion 2 a.
In the case where the upper heat-generating body 2 does not have the central low heat-generating portion 2c in the central portion thereof, as shown in the upper temperature distribution ta and the lower temperature distribution tb in the furnace of fig. 6, the temperature difference between the central portion in the width direction of the furnace 11 and the temperatures on both sides thereof is large, but in the case where the upper heat-generating body 2 has the central low heat-generating portion 2c in the central portion thereof as in the present invention, as shown in the upper temperature distribution tc and the lower temperature distribution td in the furnace of fig. 3, the temperature difference between the central portion in the width direction of the furnace 11 and the temperatures on both sides thereof can be reduced, and therefore, the uniformity of the product quality of the object to be processed can be improved.
Here, the ratio of the central low heat generation portion 2c of the upper heat generation element 2 (the ratio of H1 or H2 to H in fig. 3) is preferably 10% to 70% of the effective heating width H in the furnace. If the ratio of the central low-heat generating portion 2c is less than 10% of the effective heating width H in the furnace, the effect of providing the central low-heat generating portion 2c in the upper heat generating body 2 is reduced, and the temperature difference between the central portion and both sides may be increased. If the ratio of the central low-heat generation portion 2c is greater than 70% of the furnace effective heating width H, the temperature of the central portion may not be sufficiently increased. The present invention is particularly effective when applied to a wide continuous heating furnace having an effective heating width H of 1500mm or more.
As shown in fig. 2, the upper heating element 2 of the present embodiment includes: a first upper heat-generating body 21 having a short central low heat-generating portion 2c length h 1; and a second upper heat-generating body 22 having a length h2 of the central low heat-generating portion 2c longer than that of the first heat-generating body 21, and a third upper heat-generating body 23 having a low heat-generating portion 2a without the central low heat-generating portion 2c in the central portion. In this example, three types of upper heating elements 2 are set as 1: 1: a ratio of 1, but this is only an example. By changing the usage ratio of the upper heat generating elements 2 having different lengths of the central low heat generating portions 2c, the temperature distribution in the furnace 11 of the roller kiln 1 can be adjusted more freely.
Further, the difference in length between the central low heat generation portions 2c of the upper heat generation elements 2 adjacent in the front-rear direction of the conveyance path (for example, in fig. 2, the difference in length between the length H1 of the central low heat generation portion 2c of the first heat generation element 21 and the length H2 of the central low heat generation portion 2c of the second heat generation element 22) is preferably 10% to 90% of the effective heating width H in the furnace. By limiting the difference in length between the central low heat generating portions 2c of the upper heat generating elements 2 adjacent in the front-rear direction of the conveyance path to such a range, a smoother temperature gradient can be set.
As shown in the upper heating element 24 in fig. 4, the high heat generating portions 2a may extend into the left and right side walls 14, 15. By extending the high heat generation portions 2a into the left and right side walls 14, 15 in this manner, it is possible to suppress a decrease in the temperature of the left and right side walls 14, 15, and to further improve the uniformity of the temperature in the furnace 11. The length d2 from the boundary between the high heat generating part 2a and the low heat generating part 2b to the inner surface of the side walls 114, 115 is adjusted to 0 to 30 mm.
As the protection tube 3, a known inorganic material such as mullite, alumina, or quartz can be used. For example, when the roller kiln 1 is a continuous heating furnace for lithium iron phosphate (LFP) treatment, the firing temperature is 750 to 800 ℃, and a quartz tube is preferably used because the requirement for corrosion resistance is low. In addition, in the case of a continuous heating furnace for treating a ternary lithium ion battery positive electrode material using a compound of three elements of cobalt, nickel and manganese, the firing temperature is 800 to 1100 ℃, and a mullite tube is preferable because of high requirement for corrosion resistance. As a mullite tube, canCan use, for example, Al2O375 to 77% of SiO2Less than or equal to 15 percent and less than or equal to 0.5 percent of MgO.
According to the roller kiln 1 of the present embodiment, since the protective tube 3 covering the upper heating element 2 is provided, the upper heating element 2 can be prevented from being corroded by a substance derived from the object to be treated during the heat treatment.
Further, according to the roller kiln 1 of the present embodiment, since the upper heat generating body 2 includes the central low heat generating portion 2c in the central portion thereof, the difference between the temperature in the central portion in the width direction of the furnace interior 11 and the temperatures on both sides can be reduced, and therefore, the uniformity of the product quality of the object to be treated can be improved.

Claims (9)

1. A continuous heating furnace (1) is characterized by comprising: a plurality of rod-shaped, tubular or spiral-tubular upper heating elements (2) which are arranged above a conveying path (12) of the furnace (11) and penetrate through the left and right side walls (14, 15) of the continuous heating furnace to be arranged in parallel; and a protection tube (3) covering the upper heating element.
2. The continuous heating furnace according to claim 1,
the upper heating element includes: a central low-heat generation part (2c) formed in the central part of the upper heat generation element; and high heat generation parts (2a) formed integrally with the central low heat generation part on both sides of the central low heat generation part.
3. The continuous heating furnace according to claim 2,
the ratio of the central low heat generation part of the upper heat generation body is 10% to 70% of an effective heating width (H) in the furnace.
4. The continuous heating furnace according to claim 2,
the plurality of upper heating elements includes: a first upper heat-generating body (21) having a short length of the central low heat-generating portion; and a second upper heat-generating body (22) in which the length of the central low-heat-generating portion is longer than the length of the central low-heat-generating portion of the first heat-generating body.
5. The continuous heating furnace according to claim 4,
the difference in length between the central low heat generation portions of the upper heat generation elements adjacent in the front-rear direction of the conveyance path is 10% to 90% of the effective heating width in the furnace.
6. The continuous heating furnace according to claim 4,
the upper heat generating body further includes a third upper heat generating body (23), and the third upper heat generating body (23) has the high heat generating portion in a central portion thereof without the central low heat generating portion.
7. The continuous heating furnace according to claim 1,
the continuous heating furnace is provided with: and a plurality of rod-shaped or tubular lower heating elements (5) which are arranged below the conveying path in the furnace, penetrate through the left and right side walls of the continuous heating furnace and are arranged in parallel.
8. The continuous heating furnace according to claim 1,
the protection tube is a mullite tube, an alumina tube or a quartz tube.
9. The continuous heating furnace according to claim 2,
the high heat generating portions extend to the inside of the left and right side walls (14, 15).
CN202011096522.8A 2020-10-14 2020-10-14 Continuous heating furnace Pending CN114370762A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202011096522.8A CN114370762A (en) 2020-10-14 2020-10-14 Continuous heating furnace

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202011096522.8A CN114370762A (en) 2020-10-14 2020-10-14 Continuous heating furnace

Publications (1)

Publication Number Publication Date
CN114370762A true CN114370762A (en) 2022-04-19

Family

ID=81138833

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202011096522.8A Pending CN114370762A (en) 2020-10-14 2020-10-14 Continuous heating furnace

Country Status (1)

Country Link
CN (1) CN114370762A (en)

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