Process for sampling during titanium dioxide calcination and method of using a sampling device

Abstract

The application discloses a sampling process and a sampling device and a use method thereof during the calcination of titanium dioxide, and comprises the following steps: (1) sampling the titanium dioxide rotary kiln in operation at a certain time point t1 by using the sampling device; (2) sampling the titanium dioxide rotary kiln in operation again at another time point t2 by using the sampling device; (3) opening the sampling device and taking out the sampling samples at the time points t1 and t2. The application has the beneficial effect that the sampling device is periodically placed in the rotary kiln by utilizing the characteristics that the titanium dioxide rotates and advances in the rotary kiln, and the different positions of the sampling window in the cylindrical cavity are controlled by controlling the length of the sampling tube in the kiln, so that the automatic sampling is realized multiple times, and the sampling process does not affect the normal operation of the rotary kiln.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of titanium dioxide preparation, in particular to a sampling process during titanium dioxide calcination and a use method of a sampling device. BACKGROUND

[0002] The principle of the titanium dioxide calcination process is as follows: the filtered titanium dioxide hydrolyzate filter cake is input into the tail end of the kiln body with a certain slope and slow rotation (the high end of the cylinder), and the clean flame and hot air are blown into the kiln from the combustion mixing chamber at the head end (the low end of the cylinder) to dehydrate and calcine the filter cake. The dehydrated and calcined titanium dioxide hydrolyzate filter cake after high-temperature calcination at 1000℃ or above moves along the circumferential direction and the axial direction (from the high end to the low end) by means of the inclined rotary kiln body, continuously completing the dehydration and calcination process. Finally, the material is discharged into the cooler through the double-hydraulic flap discharge valve at the lower part of the kiln head cover, and the cooled and screened material is finally obtained after other processes. The calcination area of the titanium dioxide calcination process is divided into three sections: the kiln tail drying zone, the intermediate crystal type conversion zone, and the kiln head crystal growth zone. In the kiln tail drying zone, O and S in the material are evaporated, and in order to correctly convert the anatase type into the rutile type, it is best to remove all or most of the impurities from metatitanic acid in the drying zone; the material leaving the kiln tail drying zone is actually all anatase type crystals in addition to the rutile type added to the metatitanic acid, and this anatase type material enters the crystal conversion zone, where the high temperature is sufficient to convert the anatase type into the rutile type, and the converted rutile type then grows in crystals, so the conversion speed needs to be fast, otherwise a particularly long rotary kiln is required to produce rutile type pigments; in the kiln head crystal growth zone, the rutile type particles grow, and the residence time needs to be just right to prevent sintering and aggregation, and the average particle size of the material leaving the rotary kiln is 0.05-0.3 m, and the small particle size titanium dioxide is crushed to obtain the rutile type titanium dioxide. Due to the high temperature in the kiln, simple sampling mechanisms cannot be used to take out the titanium dioxide in the kiln for analysis, so the calcination process of the titanium dioxide cannot be observed in a timely manner, and the calcination temperature and the rotation speed of the kiln body cannot be adjusted according to the state of the titanium dioxide.

[0003] Chinese utility model patent CN217430835U discloses a sulfuric acid method titanium white calcination kiln tail gas utilization device, which comprises first collecting device, first spraying device, second collecting device, second spraying device, third collecting device and nanofiltration device connected in sequence, and gas inlet pipeline and gas outlet pipeline; the liquid outlet of the nanofiltration device is connected with the first collecting device; the gas inlet pipeline is connected with the bottom of the first spraying device and the second spraying device, and the gas outlet pipeline is connected with the top of the first spraying device and the second spraying device. The device samples the second collecting device and the third collecting device, and does not involve kiln sampling. SUMMARY

[0004] The technical problem to be solved by the present application is that the existing titanium dioxide calcining kiln does not have an online sampling process, and therefore a sampling process and a use method of a sampling device during titanium dioxide calcination are provided.

[0005] The technical solution of the present application is: a sampling process during titanium dioxide calcination, comprising the following steps: (1) using a sampling device to sample a titanium dioxide rotary kiln in operation at a certain time point t1; (2) using the sampling device again to sample the titanium dioxide rotary kiln in operation at another time point t2; (3) opening the sampling device to take out the sampling samples at the time points t1 and t2, the sampling device comprising a cylindrical cavity, the bottom of the cylindrical cavity being fixedly connected with the outer wall of the titanium dioxide rotary kiln, a sampling hole being formed in the central bottom of the cylindrical cavity, a sampling tube being slidably fitted in the sampling hole, a through hole being formed in the outer wall of the titanium dioxide rotary kiln for the sampling tube to extend into, a sampling window being formed in the lower surface of the sampling tube and facing the direction of the titanium dioxide advancing, a boss having a diameter larger than that of the sampling hole and being located in the cylindrical cavity being communicated with the top of the sampling tube, a sampling window being formed in the side of the boss and facing away from the sampling window, a plurality of annular retaining rings being fixedly connected with the inner wall of the cylindrical cavity along the height direction thereof, the inner diameter of the annular retaining ring matching the outer diameter of the boss. A piston rod is fixedly connected with the top center of the boss, the piston rod extending upward out of the top of the cylindrical cavity and being drivingly connected with a driving mechanism.

[0006] The improvement of the above-mentioned solution is that the inner bottom of the cylindrical cavity is provided with an annular pre-cooling layer, the inner diameter of the annular pre-cooling layer matching the outer diameter of the sampling tube.

[0007] In the above-mentioned solution, the side wall of the cylindrical cavity is made of transparent material.

[0008] In the above-mentioned solution, the annular retaining ring separates the cylindrical cavity into a plurality of chambers, and the outer wall of the chamber is provided with a discharge port.

[0009] The use method of the sampling device in the sampling process during titanium dioxide calcination, comprising the following steps: after the titanium dioxide rotary kiln runs for a certain time, the driving mechanism is started to push the piston rod downward, so that the sampling tube enters the titanium dioxide rotary kiln from the cylindrical cavity, the boss is located below the lowermost annular retaining ring, the titanium dioxide enters the sampling window, and the centrifugal force of the titanium dioxide rotary kiln is used to throw the titanium dioxide out of the sampling window into the cylindrical cavity, to complete the first sampling; after the titanium dioxide rotary kiln runs for a certain time, the driving mechanism is started to pull the piston rod upward, so that the boss is located above the lowermost annular retaining ring, at this time the sampling window is still located in the titanium dioxide rotary kiln, the titanium dioxide enters the sampling window, and the centrifugal force of the titanium dioxide rotary kiln is used to throw the titanium dioxide out of the sampling window into the cylindrical cavity, to complete the second sampling.

[0010] The beneficial effect of the present application is to utilize the characteristics of titanium dioxide rotating forward in the rotary kiln, periodically place the sampling device in the rotary kiln, and control the length of the sampling tube in the kiln to control the different positions of the sampling window in the cylindrical cavity, to achieve multiple automatic sampling, and the sampling process does not affect the normal operation of the rotary kiln. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a schematic diagram of the sampling device of the present application;

[0012] Figure 2 is Figure 1 is a schematic diagram of the sampling tube and the boss in the present application;

[0013] Figure 3 is Figure 1 is a schematic diagram of the sampling tube and the cylindrical cavity in the present application;

[0014] In the figure, 1 is a cylindrical cavity, 2 is a sampling tube, 3 is a sampling window, 4 is a boss, 5 is a sampling window, 6 is an annular retaining ring, 7 is a piston rod, and 8 is an annular pre-cooling layer. EMBODIMENT

[0015] The technical solutions in the present application will be described clearly and completely in combination with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments within the scope of the present application without creative labor are within the protection scope of the present application.

[0016] As Figures 1-3As shown, the sampling process during the titanium dioxide calcination includes the following steps: (1) sampling the titanium dioxide rotary kiln at a certain time point t1; (2) sampling the titanium dioxide rotary kiln at another time point t2; (3) opening the sampling device to take out the samples at the time points t1 and t2, the sampling device includes a cylindrical cavity 1, the bottom of the cylindrical cavity is fixedly connected with the outer wall of the titanium dioxide rotary kiln, and the sampling device is preferably installed in the crystal conversion zone of the kiln body, a sampling hole is formed in the center of the bottom of the cylindrical cavity, a sampling tube 2 is slidably connected in the sampling hole, a through hole is formed in the outer wall of the titanium dioxide rotary kiln for the sampling tube to extend into, a sampling window 3 facing the advancing direction of the titanium dioxide is formed in the lower surface of the sampling tube, a boss 4 with a diameter larger than the sampling hole is connected to the top of the sampling tube and located in the cylindrical cavity, a lofting window 5 opposite to the sampling window is formed in the side surface of the boss, an annular retaining ring 6 is fixedly connected to the inner wall of the cylindrical cavity along the height direction, the inner diameter of the annular retaining ring matches the outer diameter of the boss, the annular retaining ring divides the cylindrical cavity into two chambers, which can be referred to as an upper chamber and a lower chamber, the sample taken at the time point t1 is placed in the lower chamber, and the sample taken at the time point t2 is placed in the upper chamber, the number of annular retaining rings corresponds to the number of sampling times, for example, if sampling is performed three times at three time points, two annular retaining rings are needed to divide the cylindrical cavity into an upper chamber, a middle chamber and a lower chamber for storing the samples taken three times respectively. The sampling tube is completely accommodated in the cylindrical cavity under different normal conditions, and the sampling device is also in an inclined posture due to the inclined posture of the kiln body, so that the titanium dioxide can flow from the sampling window to the lofting window, a piston rod 7 is fixedly connected to the top center of the boss, the piston rod extends upward out of the top of the cylindrical cavity and is drivingly connected with a driving mechanism.

[0017] As a preferred example of the present application, an annular pre-cooling layer 8 is arranged at the inner bottom of the cylindrical cavity, and the inner diameter of the annular pre-cooling layer matches the outer diameter of the sampling tube. When the titanium dioxide flows in the sampling tube to the lofting window, the pre-cooling of the annular pre-cooling layer prevents high temperature from causing burns to the cylindrical cavity or personnel.

[0018] As a preferred example of the present application, the side wall of the cylindrical cavity is made of transparent material, so that the sampling conditions of the samples in each chamber can be directly observed. Further, in order to facilitate the titanium dioxide to be taken out for analysis, the annular retaining ring divides the cylindrical cavity into a plurality of chambers, and the outer wall of the chamber is provided with a discharge port.

[0019] The application discloses a sampling device and a sampling method for titanium dioxide calcination. The sampling device comprises a cylinder-shaped cavity, a sampling window, a piston rod, a piston, a convex boss, a ring-shaped stop ring, a driving mechanism and a sampling tube. The sampling method comprises the following steps: after the titanium dioxide rotary kiln runs for a certain time, the driving mechanism is started to push down the piston rod, so that the sampling tube enters the titanium dioxide rotary kiln from the cylinder-shaped cavity, the convex boss is located below the lowermost ring-shaped stop ring, the titanium dioxide enters the sampling window, the centrifugal force of the titanium dioxide rotary kiln is utilized to throw the titanium dioxide out of the sampling window and into the cylinder-shaped cavity, and one-time sampling is completed; after the titanium dioxide rotary kiln runs for a certain time again, the driving mechanism is started to pull up the piston rod, so that the convex boss is located above the lowermost ring-shaped stop ring, at this time, the sampling window is still located in the titanium dioxide rotary kiln, the titanium dioxide enters the sampling window, the centrifugal force of the titanium dioxide rotary kiln is utilized to throw the titanium dioxide out of the sampling window and into the cylinder-shaped cavity, and two-time sampling is completed.

Claims

1. Process for sampling during the calcination of titanium white, characterized in that: It comprises the following steps: (1) sampling device for running in the titanium dioxide rotary kiln at a certain time point t1; (2) again using sampling device for running in the titanium dioxide rotary kiln at another time point t2; (3) open sampling device, take out t1 time point and t2 time point sampling sample, the sampling device comprises a cylindrical cavity (1), the bottom of the cylindrical cavity is fixedly connected with the outer wall of the titanium dioxide rotary kiln, the bottom of the cylindrical cavity is provided with a sampling hole, the sampling hole is slidably connected with a sampling tube (2), the outer wall of the titanium dioxide rotary kiln is provided with a through hole for the sampling tube to extend into, the lower surface of the sampling tube is provided with a sampling window (3) facing the advancing direction of titanium dioxide, the top of the sampling tube is connected with a boss (4) with a diameter larger than the sampling hole and located in the cylindrical cavity, the side surface of the boss is provided with a loft window (5) facing away from the sampling window, the inner wall of the cylindrical cavity is fixedly connected with a plurality of annular retaining rings (6) along the height direction, the inner diameter of the annular retaining ring matches the outer diameter of the boss, the top center of the boss is fixedly connected with a piston rod (7), the piston rod extends upward out of the top of the cylindrical cavity and is drivingly connected with a driving mechanism; the annular retaining ring divides the cylindrical cavity into a plurality of chambers, and the chamber outer wall is provided with a discharge port.

2. The process for sampling while calcining titanium dioxide according to claim 1, characterized in that: The inner bottom of the cylindrical cavity is provided with an annular precooling layer (8), and the inner diameter of the annular precooling layer matches the outer diameter of the sampling tube.

3. The process for sampling while calcining titanium dioxide according to claim 1, characterized in that: The side wall of the cylindrical cavity is of transparent material.

4. The method of using a sampling device in a process for sampling during the calcination of titanium dioxide according to claim 1, characterized in that: It comprises the following steps: After the titanium dioxide rotary kiln runs for a certain time, the driving mechanism is started to push the piston rod down, so that the sampling tube enters the titanium dioxide rotary kiln from the cylindrical cavity, the boss is located below the lowermost annular retaining ring, the titanium dioxide enters the sampling window, and the centrifugal force of the titanium dioxide rotary kiln is used to throw the titanium dioxide out of the loft window into the cylindrical cavity, completing the sampling; after the titanium dioxide rotary kiln runs for a certain time, the driving mechanism is started to pull the piston rod up, so that the boss is located above the lowermost annular retaining ring, at this time the sampling window is still located in the titanium dioxide rotary kiln, the titanium dioxide enters the sampling window, and the centrifugal force of the titanium dioxide rotary kiln is used to throw the titanium dioxide out of the loft window into the cylindrical cavity, completing the second sampling.

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