Automatic quick response temperature measurement for rotary kilns

Abstract

A device for measuring the temperature in a rotary kiln through which solid material passes being heated to elevated temperatures. The device features a drive as well as an elongated hollow body with means to fix a thermocouple, whereby the drive and the elongated hollow body are mounted such that they rotate jointly with the rotary kiln. The drive can move the elongated hollow body together with thermocouple through an opening in and out of the rotary kiln interior for measuring the temperature inside the rotary kiln during operation.

Claims

1. A device for measuring the temperature in a rotary kiln through which solid material passes being heated to elevated temperatures, comprising a drive as well as an elongated hollow body having a thermocouple supported therein, whereby the drive and the elongated hollow body are mounted such that they rotate jointly with the rotary kiln and that the drive can move the elongated hollow body together with the thermocouple through an opening in and out of the rotary kiln interior for measuring the temperature inside the rotary kiln during operation, wherein the elongated hollow body is tubular and the thermocouple is configured to be shifted by an actuator such that a temperature sensitive tip of the thermocouple protrudes out of the elongated hollow body; the thermocouple is designed such that it can be moved separately from the elongated hollow body in and out for better protection of the thermocouple; a magazine providing at least the thermocouple and another thermocouple and/or the elongated hollow body and at least another elongated hollow body.

2. The device according to claim 1, wherein the elongated hollow body is tapered at the side directed to the rotary kiln.

3. The device according to claim 1, wherein the drive is an electric motor.

4. The device according to claim 1, wherein a protection pipe is provided between the elongated hollow body and the thermocouple.

5. The device according to claim 1, wherein the movement of the drive is transmitted to the elongated hollow body and/or the thermocouple by means of at least one worm wheel.

6. The device according to claim 1, wherein the magazine is exchangeable.

7. The device according to claim 1, wherein the magazine is a drum magazine.

8. The device according to claim 1, wherein the magazine is rotated by a Geneva drive.

9. A rotary kiln, wherein at least one device for temperature measurement according to claim 1 is mounted of the rotary kiln.

10. A method for temperature measurement in a rotary kiln, characterized in that temperature measured with a device according to claim 1.

11. A method according to claim 10, wherein the actuator is rotated such that a time duration of one temperature measurement is at least the time needed for one revolution of the rotary kiln.

Description

(1) The drawings show schematically:

(2) FIG. 1 shows schematically the semi-automatic solution as a first embodiment of the device according to the invention with two spindles and two worm wheels,

(3) FIG. 2 shows schematically a second view of the semi-automatic solution as a first embodiment of the device according to the invention with two spindles and two worm wheels,

(4) FIG. 3 shows schematically a close up of the thermocouple in the elongated hollow body in the semi-automatic solution,

(5) FIG. 4 shows schematically the fully-automatic solution as a second embodiment using a drum magazine,

(6) FIG. 5 shows schematically a section of a rotary kiln with a thermocouple inside and

(7) FIG. 6 shows schematically a temperature profile during one revolution of a rotary kiln during operation.

(8) FIG. 1 shows a first and semi-automatic embodiment of the invention. Therein, a device 10 is installed on the rotary kiln shell 33 and executes the work steps for the temperature measurement.

(9) In detail, a thermocouple 12 is located in an elongated hollow body 11. For a high speed of response its measuring tip 13 is either permanently outside of the elongated hollow body 11 or the thermocouple 12 can be moved separately such that its tip 13 is moved in and out of the elongated hollow body 11. The thermocouple 12 is preferably protected by a protection pipe 14, leaving the measuring tip 13 exposed to allow for the quick response to temperature changes.

(10) For the latter case, it is preferred that the tip 13 can be positioned outside of the elongated hollow body 11 by an actuator 25 on top of the elongated hollow body 11. The actuator 25 shifts the thermocouple 12 together with the protection pipe 14. In the stand-by position the elongated hollow body 11 is located in an opening 31 in the refractory lining 37 of the rotary kiln to protect it against wear of the material and high temperatures/temperature changes. The opening 31 is protected by a sleeve 36 so that a possible displacement of the refractory lining 37 does not damage the elongated hollow body 11. Typically, the sleeve 36 is made from heat resistant steel.

(11) Preferably, the installation and de-installation of the elongated hollow body 11 at the rotary kiln shell 33 can be done quickly, e.g. by means of a bayonet fitting. But in normal operation only the thermocouple 12 with the protection pipe 14 has to be changed occasionally.

(12) Further, two spindles 21 are shown which are fixed, parallel to each other, at the ground flange 26 of the device 10 which in turn is mounted on a flanged nozzle on the shell of the rotary kiln 30. The spindles are supported by a frame 28, which is not shown in the figure. The worm wheels 22 with the spindle nuts are attached at the plate 24 in such a way that they are able to rotate without changing their position relative to the plate 24; they are rotated by the worm 23 which in turn is driven by the drive 20. Preferably, the drive 20 is an electric motor. The plate 24, the worm wheels 22, the worm 23 and the drive 20 move up and down the spindles 21, together with the elongated hollow body 11, the thermocouple 12 and the protection pipe 14, when the drive 20 is operated.

(13) The elongated hollow body 11, preferably made of heat resistant steel, is fixed with a bayonet fitting to the plate 24. This design allows a linear movement of the elongated hollow body 11 with a high force and a self-locking effect.

(14) For the breakthrough of accretions the drive 20 moves the plate 24 and the elongated hollow body 11 through the opening 31 into the rotary kiln 30. To prevent thick accretions in front of the opening 31, this will be done in defined temporal intervals. Once the opening 31 is free of accretions, the thermocouple 12 with the protection pipe 14 can be shifted forward into the measurement position in the interior 32 of the rotary kiln by means of the actuator 25. In this measurement position the measuring tip 13 of the thermocouple 12 is not surrounded by the elongated hollow body 11 for a quick response temperature measurement

(15) According to both the semi-automatic and the fully-automatic embodiment of the invention the quick response temperature measurement is working in an automated way. When a temperature measurement is required, the automatic working procedure can be initialized in the control room. No operating personnel are needed on-site during the measurement.

(16) FIG. 2 shows a device 10 identical to the one of FIG. 1 in a second view.

(17) FIG. 3 shows a detail of FIGS. 1 and 2 wherein an additional protection pipe 14 in the elongated hollow body 11 supports the thermocouple 12. To achieve the stand-by position of the thermocouple 12, the protection pipe 14 can be pulled back into the tip of the elongated hollow body 11 together with the thermocouple 12. During the measurement only the measurement tip 13 of the thermocouple 12 is unprotected.

(18) FIG. 4 discloses a fully-automatic solution for changing the thermocouples 12 together with the protection pipes 14 automatically. The principal design of this device 10 is similar to the semi-automatic solution, but the elongated hollow body 11 has a larger diameter and contains a magazine 40, e.g. a drum magazine, loaded with thermocouples 12 and protection pipes 14.

(19) The mechanism for the automatic change of thermocouples is arranged on top of the elongated hollow body 11 and consists of a drive motor 43, a magazine drive 42, e.g. a Geneva drive, for the stepwise rotation of the magazine 40, and a mechanism 41, e.g. a cylindrical cam mechanism to convert the rotational movement of the drive motor 43 into an axial movement of the thermocouples 12.

(20) In this embodiment of the invention a number of thermocouples 12 positioned eccentrically in the elongated hollow body, but in the bottom of the elongated hollow body there is only one eccentric hole, through which the selected thermocouple can be shifted into the measuring position. However, the opening 31 in the shell of the rotary kiln 30 and its refractory lining 37 is concentric to the centerline of the elongated hollow body 11.

(21) In the stand-by position of the elongated hollow body 11 a round steel bar seals the eccentric opening in the bottom of the elongated hollow body 11. To start a measurement, the elongated hollow body 11 is first moved by means of the drive 20 into the interior 32 of the rotary kiln 30 to break any accretions and then the thermocouple changing mechanism 41 and 42 positions a thermocouple 12 through the eccentric opening in the bottom of the elongated hollow body 11 into its measuring position in the interior of the rotary kiln. In case of a defect thermocouple 12, the mechanism stops at the next position of the magazine 40. If all thermocouples 12 are defect, the magazine 40 can be changed manually.

(22) In a preferred embodiment of the invention the change of a thermocouple is only affected when the opening 31 is not filled with solid material, i.e. the device 10 is in a high position, e.g. as shown in FIG. 4.

(23) FIG. 5 depicts a section of a rotary kiln 30 with a thermocouple 12 protruding inside. The rotary kiln features a gas phase 35 and is partially filled with solid particles 34. The solid particles 34 do not rotate together with the rotary kiln 30, but always remain in the shown position. So during one revolution of the rotary kiln 30 in the direction of rotation 38 the thermocouple 12 is first measuring the temperature of the gas phase and then the temperature of the solid particles.

(24) FIG. 6 shows schematically a temperature profile during one revolution of the rotary kiln during operation. As it can be seen, sudden temperature changes are measured when the thermocouple is immersed into the solid particles and when it emerges from the solid particles.

(25) To determine the thickness of the accretion layer in the kiln, a change in the temperature profile during movement of the elongated hollow body 11 into the kiln will be used. Therefore, the accretions in front of the opening 31 are broken and the actuator 25 has positioned the thermocouple in measurement position. The temperature change during moving in of the elongated hollow body with the measuring tip 13 in measuring position is caused by a higher heat transfer outside the accretion layer because of the gas velocity and the thermal radiation in the kiln. With the information of the accretion thickness, the elongated hollow body can be positioned accordingly by means of the drive 20, and the measurement can start.

(26) Alternatively the temperature gradient between temperature from the kiln inside and from the shell temperature can be used for a determination of the accretion thickness.

LIST OF REFERENCE NUMERALS

(27) 10 device 11 elongated hollow body 12 thermocouple 13 thermocouple measurement tip 14 protection pipe 20 drive 21 spindle 22 worm wheel 23 worm 24 plate 25 actuator 26 ground flange 27 bayonet fitting 28 frame 30 rotary kiln 31 opening 32 rotary kiln interior 33 rotary kiln shell 34 solid particles 35 gas phase 36 sleeve 37 refractory lining 38 direction of rotation 40 magazine 41 cylindrical cam mechanism 42 Geneva drive 43 drive motor