CN114487025B - Method for controlling content of crystal water in hydrate and application thereof - Google Patents
Method for controlling content of crystal water in hydrate and application thereof Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 125
- 239000013078 crystal Substances 0.000 title claims abstract description 114
- 238000000034 method Methods 0.000 title claims abstract description 63
- 229910052602 gypsum Inorganic materials 0.000 claims abstract description 84
- 239000010440 gypsum Substances 0.000 claims abstract description 84
- 238000012544 monitoring process Methods 0.000 claims abstract description 76
- 238000001354 calcination Methods 0.000 claims abstract description 68
- 239000000463 material Substances 0.000 claims abstract description 10
- 101000872083 Danio rerio Delta-like protein C Proteins 0.000 claims description 10
- 238000002425 crystallisation Methods 0.000 claims description 8
- 230000008025 crystallization Effects 0.000 claims description 8
- 238000004364 calculation method Methods 0.000 claims description 6
- 150000004683 dihydrates Chemical class 0.000 claims description 5
- 230000001276 controlling effect Effects 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 7
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical compound O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 150000004677 hydrates Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/041—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
- C04B11/028—Devices therefor characterised by the type of calcining devices used therefor or by the type of hemihydrate obtained
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Abstract
The invention relates to the field of material treatment, in particular to a method for controlling the content of crystal water in hydrate and application thereof. The method comprises the following steps: monitoring the hydrate by using monitoring points N 1 to N i to obtain a monitoring signal, wherein the monitoring signal comprises the immediate conductivities R 1 to R i of the hydrate, i is an integer more than or equal to 3, and the monitoring points are arranged on the travelling route of the hydrate; determining target conductivities R 01 to R 0i corresponding to monitoring points N 1 to N i; calculating a deviation of the instantaneous conductivity from the target conductivity, and adjusting a calcination condition of the travel route based on the deviation. The method can conveniently and effectively control the content of the crystal water to meet the set requirement, and can realize high uniformity. The method is particularly suitable for the process of removing crystal water by gypsum calcination.
Description
Technical Field
The invention relates to the field of material treatment, in particular to a method for controlling the content of crystal water in hydrate and application thereof.
Background
Because the formation temperature areas of some phases in the calcined gypsum are staggered, the gypsum produced under certain conditions is a mixed phase mainly comprising a certain phase, wherein the mixed phase can comprise dihydrate gypsum, hemihydrate gypsum, soluble anhydrous gypsum and anhydrous gypsum AII. Crystal water is an important guiding parameter for controlling the quality of building gypsum. Theoretically, as much hemihydrate gypsum as possible, i.e., as much as approximately 6.2% of the building gypsum crystal water, is produced. Whereas the purity of gypsum used in actual production is almost impossible to be 100%, if used for construction gypsum, the purity is generally 75% to 90%. Therefore, to achieve the best quality of the product, it is necessary to control the crystal water content of the building gypsum more accurately and precisely so as to be as close to 6.2% x a (a% is the actual purity of the gypsum used) as possible. For example, if the actual purity of gypsum is 85%, the actual theoretical value of the crystal water content of the building gypsum is 5.27%. That is, in order to produce building gypsum from gypsum having a purity of 85%, the crystal water should be incorporated by as much as 5.27% as possible in order to obtain as much hemihydrate gypsum as possible.
However, in actual production, it is impossible to strictly control the crystal water to a theoretical value of 5.27%. In actual production, the content of crystal water can be greatly fluctuated between different batches and different positions of the same batch of calcined gypsum.
However, the content and uniformity of the crystal water have a great influence on the performance of gypsum, and thus a method for conveniently and effectively controlling the crystal water content is very important.
Disclosure of Invention
The invention aims to solve the problem that the content of crystal water of hydrate (such as gypsum) is difficult to effectively control in the prior art, and provides a method for controlling the content of crystal water in the hydrate and an application thereof. The method can conveniently and effectively control the content of the crystal water to meet the set requirement, and can realize high uniformity. The method is particularly suitable for the process of removing crystal water by gypsum calcination.
In order to achieve the above object, a first aspect of the present invention provides a method of controlling the content of crystal water in a hydrate, comprising:
Monitoring the hydrate by using monitoring points N 1 to N i to obtain a monitoring signal, wherein the monitoring signal comprises the immediate conductivities R 1 to R i of the hydrate, i is an integer more than or equal to 3, and the monitoring points are arranged on the travelling route of the hydrate;
Determining target conductivities R 01 to R 0i corresponding to monitoring points N 1 to N i;
calculating a deviation of the instantaneous conductivity from the target conductivity, and adjusting a calcination condition of the travel route based on the deviation.
The first two steps are not limited to the sequence in actual operation.
In an example, the method further comprises: and establishing a functional relation F (x) of the conductivity of the hydrate and the crystal water, and calculating the instant crystal water contents C 1 to C i respectively corresponding to the instant conductivities R 1 to R i according to the F (x).
In one example, the monitoring point N 1 is located at the entrance of the travel route for determining a monitoring signal including the instantaneous conductivity R 1 as soon as the hydrate enters the calcination environment.
In one example, the monitoring point N i (i takes the maximum of the selectable values) is located at the exit of the travel route for determining a monitoring signal including the instantaneous conductivity R i after the hydrate calcination is completed.
In one example, the means for determining the target conductivity comprises: the target conductivity R 0i after the hydrate calcination is determined, and then the target conductivities R 02 to R 0i-1 of the monitoring points N 2 to N i-1 are determined through a gradient calculation method according to the initial instant conductivity R 1 and the target conductivity R 0i.
In one example, the calculating the deviation of the instantaneous conductivity from the target conductivity further comprises: further calculating the deviation delta C c of the instant crystal water content and the target crystal water content; and adjusting the calcination conditions of the travel route based on the Δc c.
In one example, the means for adjusting the calcination conditions includes: adjusting the rotary kiln rotation speed to V=V 0+△V,V0 to be the current rotary kiln rotation speed, wherein the sign of DeltaV is opposite to that of DeltaC c; when DeltaC c is positive, deltaV is negative, namely, the rotary kiln rotates slowly; when DeltaC c is a negative number, deltaV is a positive number, namely the rotary kiln rotates quickly.
In one example, the means for adjusting the calcination conditions further comprises: setting a threshold deviation, wherein the threshold deviation is a determined value less than or equal to delta 10%; performing said adjusting of the calcination conditions when the absolute value of said Δc c is greater than said threshold deviation; when the absolute value of Δc c is not greater than the threshold deviation, no operation may be performed.
In one example, the material to be treated comprising the hydrate comprises greater than 50% by weight of gypsum dihydrate.
A second aspect of the invention provides the use of the method of the first aspect of the invention in controlling the crystal water content of a gypsum from a furnace in a gypsum calcination process.
The method can monitor and adjust the calcination conditions in real time in the calcination process, thereby being capable of adapting to the requirements of various changed target crystal water contents and efficiently producing the discharged gypsum which meets the requirements accurately and has uniform quality.
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
Drawings
FIG. 1 is a F (x) fitting function of example 1 for determining the change in conductivity versus crystal water content.
Detailed Description
The present invention will be described in detail by examples. The described embodiments of the invention are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The prior art method for controlling the crystal water content is to calculate the removal rate of crystal water by weighing the outlet gypsum, and then adjust the calcination conditions accordingly. The inventors of the present invention found that this control mode has the following problems: 1. hysteresis, the content of crystal water can be obtained after gypsum is calcined, and if the hysteresis is found to be unsatisfactory, obvious economic loss can be brought; 2. it is difficult to precisely control and adjust, for example, a factory always produces gypsum with 5% crystal water content, a set of ideal calcination conditions is determined in empirical search, but if gypsum with 8% crystal water content is suddenly required to be produced in one day, the factory can hardly quickly find the proper calcination conditions, so that the required gypsum is difficult to be produced quickly, and more economic loss is caused in the process of re-searching.
Accordingly, the inventors of the present invention have made an effort to develop a method capable of monitoring and adjusting the calcination conditions in real time during the calcination process, thereby ensuring that the resulting product can accurately reach the set crystal water content. The method of the invention can be suitable for various hydrates, especially gypsum of various sources, and can rapidly and accurately produce products with various crystal water contents meeting the requirements.
The method for controlling the content of crystal water in the hydrate comprises the following steps:
Monitoring the hydrate by using monitoring points N 1 to N i to obtain a monitoring signal, wherein the monitoring signal comprises the immediate conductivities R 1 to R i of the hydrate, i is an integer more than or equal to 3, and the monitoring points are arranged on the travelling route of the hydrate;
Determining target conductivities R 01 to R 0i corresponding to monitoring points N 1 to N i, wherein i is an integer more than or equal to 3;
calculating a deviation of the instantaneous conductivity from the target conductivity, and adjusting a calcination condition of the travel route based on the deviation.
The first two steps are not limited to the sequence in actual operation.
According to the method, the crystallization water is converted into the conductivity, so that the real-time monitoring of the removal degree of the crystallization water of the hydrate is realized, the calcination condition can be timely adjusted in the calcination process, and the product with the target crystallization water content can be controllably and accurately achieved.
Thus, preferably, the method further comprises: and establishing a change relation F (x) of the conductivity of the hydrate and the crystal water.
In one example, the method of the present invention further comprises: according to the change rule of F (x), the instant crystal water contents C 1 to C i respectively corresponding to the instant conductivities R 1 to R i are obtained.
The relationship F (x) will vary from hydrate to hydrate, and therefore the relationship F (x) of conductivity of the hydrate to water of crystallization is preferably established prior to the method of controlling water of crystallization. The method for establishing the functional relation can be used for establishing a scatter diagram containing enough data by measuring the conductivities corresponding to different crystal water contents, and then fitting to obtain the functional relation F (x).
In the present invention, the crystal water of the hydrate may be removed by placing the hydrate on a traveling path filled with a calcination environment, for example, in a rotary kiln in which a material in a pipe shape is tumbling and stirring.
And monitoring points N 1 to N i are sequentially arranged on the travelling route and are used for monitoring the hydrate so as to obtain monitoring signals. i is the total number of monitoring points arranged on the travelling route, i can be an integer more than or equal to 3, preferably an integer more than or equal to 5, and more preferably an integer from 5 to 8.
In one example, the monitoring point N 1 is located at the entrance of the travel route for determining a monitoring signal including the instantaneous conductivity R 1 as soon as the hydrate enters the calcination environment.
In one example, the monitoring point N i is located at the exit of the travel route for determining a monitoring signal including the instantaneous conductivity R i after the hydrate calcination is completed.
The positional relationship between the monitoring points N 1 to N i is not particularly limited, and may be uniformly distributed or unevenly distributed on the travel route.
The monitoring points divide the travel route into a plurality of correction segments, and the correction segments are named through the numbers of the monitoring points of the two endpoints. The correction segment may include a correction segment L ab, a+1=b, as L 12、L23……L(i-1)i, determined by adjacent monitoring points; the correction segment can also comprise a correction segment L ac determined by non-adjacent monitoring points, a+n=c, and n is an integer not less than 2.
The method of the invention comprises the following steps: target conductivities R 01 to R 0i corresponding to the monitoring points N 1 to N i are determined.
The manner of determination includes, for example: the target conductivity T i after the hydrate calcination is determined, and then the target conductivities R 02 to R 0i-1 of the monitoring points N 2 to N i-1 are determined through a gradient calculation method according to the initial instant conductivity R 1 and the target conductivity R 0i.
In an example, the method further comprises: the target crystal water contents D 1 to D i corresponding to the target conductivities R 01 to R 0i of the respective monitoring points N 1 to N i can be obtained, for example, from the foregoing F (x).
The gradient calculation method is a calculation method commonly used in mathematics, and the method is briefly described as follows: the monitoring data (R i) of the same monitoring point (N i) in any time period (delta t 1) is counted to obtain delta R 1＝Ri-R0i, and the average value of the delta t 1)ΔR1 in the time period is obtainedAnd so on, the monitoring data (R j) of the monitoring point (N i) in any time period (delta t j) (j is more than or equal to 1 and is an integer) is counted to obtain delta R j＝Rj-R0i, and the average value of the delta t j)ΔRj in the time period is obtainedAccording to the gradient calculation result, the calcination conditions are adjusted so that/>Approaching 0 indefinitely.
The method of the invention comprises the following steps: calculating a deviation of the instantaneous conductivity from the target conductivity, and adjusting a calcination condition of the travel route based on the deviation.
The calcination conditions include, for example: calcination temperature, travel speed, stirring speed, or rotary kiln rotational speed (rotary kiln rotation about a central axis), etc.
Preferably, calculating the deviation of the instantaneous conductivity from the target conductivity further comprises: further calculating the deviation between the instant crystal water content and the target crystal water content; and adjusting the calcination conditions of the travel route based on the deviation of the instant crystal water content from the target crystal water content.
In one example, the means for adjusting the calcination conditions may include: obtaining the instant crystal water content C c at the monitoring point N c, and calculating the deviation DeltaC c＝(Dc-Cc)÷Dc multiplied by 100% between the instant crystal water content C c and the target crystal water content of the monitoring point; adjusting the calcination temperature and/or the rotary kiln rotation speed according to DeltaC c; c is an integer between 1 and i.
And adjusting the rotary kiln rotating speed to V=V 0+△V,V0 to be the current rotary kiln rotating speed, wherein DeltaV is the adjusting quantity. Then Δv is of opposite sign to the Δc c; when DeltaC c is positive, indicating that the instant crystal water content is lower than the target crystal water content, enabling DeltaV to be negative, namely slowing down the rotary kiln; when DeltaC c is negative, the instant crystal water content is higher than the target crystal water content, and DeltaV is positive, namely the rotary kiln rotates quickly.
Preferably, the means for adjusting the calcination conditions further includes: setting a threshold deviation which is less than or equal to a certain value of Delta10% (for example Delta10%, delta9%, delta8%, delta7%, delta6%, delta5%, delta4%, delta3%, delta2%, delta1%); performing said adjusting of the calcination conditions when the absolute value of said Δc c is greater than said threshold deviation; when the absolute value of Δc c is not greater than the threshold deviation, no action may be taken or adjustments may be made within the range of the previous adjustment (i.e., fine tuning is performed).
Preferably, the hydrate to be treated is gypsum. In one example, the gypsum includes gypsum dihydrate (CaSO 4·2H2 O) containing 2 molecules of crystal water after pretreatment. The content of free water in the gypsum is not particularly limited, since free water contained in the gypsum can be removed quickly under calcination conditions.
The material to be treated may also contain water and various other impurities.
According to one embodiment, the material to be treated contains gypsum. Preferably, the content of dihydrate gypsum in the material to be treated is above 50% by weight, preferably above 80% by weight.
A second aspect of the invention provides the use of the method of the first aspect of the invention in controlling the crystal water content of kiln-exit gypsum in a gypsum calcination process.
The method of the first aspect of the invention is particularly suitable for use in gypsum calcination processes. Depending on the application, the kiln-outlet gypsum usually needs to contain about 0.5 crystal water (namely, semi-hydrated gypsum CaSO 4·0.5H2 O), however, the prior art cannot monitor the content of crystal water in real time in the calcining process, so that the removal effect of crystal water can only be measured after discharging, and the required target content of crystal water is difficult to ensure.
The method can monitor and adjust the calcination conditions in real time in the calcination process, thereby being capable of adapting to the requirements of various changed target crystal water contents and efficiently producing the discharged gypsum which meets the requirements accurately and has uniform quality.
Specific embodiments of the invention will be schematically illustrated by the following examples, which are not intended to limit the scope of the invention.
The gypsum to be treated selected in the following examples was gypsum after the drying pretreatment, and the purity of gypsum was found to be 85%.
Example 1
The purpose of this example was to obtain a building gypsum, and the target crystal water content after the calcination in this example was set to 5.27% based on the ideal crystal water content of the building gypsum of 5.27%.
(1) Construction of variational relationship
Taking a small amount of the gypsum to be treated, and testing the change relation F (x) of the conductivity and the crystal water under laboratory conditions, wherein the concrete process comprises the following steps: carrying out short-time calcination treatment on the time to be treated, wherein each calcination time is 2-5 minutes, and measuring conductivity and crystallization water data after taking out; this operation was repeated until the water of crystallization was below 0.1. A scatter diagram is drawn with the crystal water content (unit: wt%) as abscissa and the conductivity (unit: ms/cm) as ordinate, and as shown in fig. 1, a computer fitting function equation F (x), F (x) =1.00093+0.92052/(1+exp (x-x 0)/dx)),R2＝0.9957,x0) is the crystal water content in the gypsum to be treated.
(2) Preparation for calcination
A long tubular rotary kiln with the length of 34m and the inner diameter of 2.8m is prepared, a first monitoring point N 1 is arranged at the inlet of the rotary kiln, a6 th monitoring point N 6 is arranged at the outlet, and N 2、N3、N4 and N 5 are respectively arranged at the positions 10m, 15m, 20m and 25m away from the inlet. The rotary kiln is divided into a L 12 section, a L 23 section, a L 34 section, a L 45 section and a L 56 section in sequence by 6 monitoring points, the rotary kiln rotating speed V is adjusted by taking the phosphogypsum material crystal water of the L 56 section as a final index, and the quality of the discharged material is ensured.
The initial conductivity of the gypsum is measured to be 0.9969ms/cm (namely, the instant conductivity data measured by the monitoring point N 1), and the gypsum is substituted into the function equation F (x) obtained in the step (1) to calculate so as to obtain the crystal water content to be 17.8%.
According to the initial crystal water content and the target crystal water content, the target crystal water content of N 2 was set to 14.1%, the target crystal water content of N 3 was set to 11.75%, the target crystal water content of N 4 was set to 9.94%, the target crystal water content of N 5 was set to 8.14%, and the target crystal water content of N 6 was set to 5.27%. According to the functional change relation F (x) of the conductivity of the hydrate and the crystal water, target conductivities R 2 to R 6 corresponding to N 2 to N 6 are 0.9087ms/cm, 0.6141ms/cm, 0.3175ms/cm, 0.1612ms/cm and 0.0926ms/cm respectively.
(3) Calcination process
And feeding the gypsum to be treated into the rotary kiln, turning the gypsum to be treated in the rotary kiln, and moving the gypsum to an outlet at a speed of 0.3 m/min. The initial calcination temperature is 400 ℃, and the rotating speed of the rotary kiln is 30r/min; testing the instant conductivity of each monitoring point, calculating the conductivity deviation, and adjusting the rotating speed when the conductivity deviation exceeds the threshold deviation (set as 3 percent);
Time 1: the gypsum reaches a N 2 monitoring point, the instant conductivity is measured to be 0.9655ms/cm, the deviation relative to the target conductivity R 2 is 6.25%, the threshold deviation is exceeded, and the rotating speed of the rotary kiln is adjusted to be 25R/min;
Time 2: the gypsum reaches a N 3 monitoring point, the instant conductivity is measured to be 0.6433ms/cm, the deviation between the gypsum and the target conductivity R 3 is 4.76%, and the rotating speed of the rotary kiln is adjusted to be 27R/min when the deviation exceeds a threshold deviation;
Time 3: the gypsum reaches a N 4 monitoring point, the instant conductivity is 0.3277ms/cm, the deviation between the gypsum and the target conductivity R 4 is 3.22%, the deviation exceeds a threshold deviation, and the rotating speed of the rotary kiln is finely adjusted to 29R/min;
Time 4: the gypsum reaches an N 5 monitoring point, the instant conductivity is 0.1626ms/cm, and the deviation between the gypsum and the target conductivity R 5 is 0.85%;
through detection, the actual average crystal water content of the discharged gypsum is 5.22%, the uniformity is 95%, and the product meets the requirements of high-quality products.
The uniformity test mode is as follows: in the same batch of kiln-outlet gypsum products, randomly taking a plurality of (not less than 20 parts) samples with different directions to determine crystal water, wherein if the crystal water is within a range of 'target crystal water content +/-3 percent', the crystal water is regarded as reaching an expected value, otherwise, the crystal water is regarded as not reaching the expected value; then, uniformity=number of parts up to the desired value ∈100% of total parts.
The actual crystal water content is an average value of the crystal water contents of the above samples.
Further, 10 furnaces were continuously operated in the same manner as in example 1, with a target crystal water content of 5.27%. The actual average crystal water content of the 10 furnaces is measured to be within the range of target crystal water content +/-3%, and the uniformity is more than 92%.
Example 2
The same gypsum as in example 1 was used, except that the target crystal water content of this example was 8.00%. The method of the present embodiment for embodying the present invention can obtain gypsum products of any crystal water content as required, thereby being applicable to various application modes.
(1) The variation relation F (x) is the same as in example 1.
(2) The same rotary kiln and monitoring points as in example 1 were used. According to the initial crystal water content and the target crystal water content, the target crystal water content of N 2 was set to 14.1%, the target crystal water content of N 3 was set to 11.65%, the target crystal water content of N 4 was set to 9.94%, and the target crystal water content of N 5 was set to 8.14%. According to the functional change relation F (x) of the conductivity of the hydrate and the crystal water, target conductivities R 2 to R 5 corresponding to N 2 to N 5 are 0.9087, 0.6141, 0.3175 and 0.1612 respectively.
(3) Calcination process
The amount of gypsum to be treated and the moving speed were the same as those of example 1.
Time 1: the gypsum reaches a N 2 monitoring point, the instant conductivity is 0.9793ms/cm, the deviation relative to the target conductivity R 2 is 7.77%, the deviation exceeds a threshold deviation (3%), and the rotating speed of the rotary kiln is regulated to 24R/min;
Time 2: the gypsum reaches a N 3 monitoring point, the instant conductivity is 0.6396ms/cm, the deviation between the gypsum and the target conductivity R 3 is 4.16%, and the rotating speed of the rotary kiln is adjusted to be 28R/min when the deviation exceeds a threshold deviation;
Time 3: the gypsum reaches a N 4 monitoring point, the instant conductivity is 0.3228ms/cm, the deviation between the gypsum and the target conductivity R 3 is 1.67%, the deviation does not exceed a threshold deviation, and the rotating speed of the rotary kiln is finely adjusted to 29R/min;
Through detection, the actual average crystal water content of the kiln-outlet gypsum is 8.08%, the uniformity is 93%, and the requirements of high-quality products are met.
10 Furnaces were continuously operated in the manner of example 2 with a target crystal water content of 8.00%. The actual average crystal water content of the 10 furnaces is measured to be within the range of target crystal water content +/-3%, and uniformity is greater than 91%.
It can be seen that the method of the invention flexibly adjusts the process control according to the set requirement of the target crystal water content at any time, so that the obtained product can more accurately reach the target requirement.
Comparative example 1
The same gypsum as in example 1 was used, and the target crystal water content was also 5.27%.
This comparative example was carried out in a manner conventional in the art by charging gypsum into a rotary kiln and calcining under empirically obtained calcining conditions constantly.
This comparative example was conducted using the same rotary kiln as in example 1 in the same amount and moving speed of gypsum to be treated as in example 1.
Except that the calcination conditions were kept constant under the initial conditions of example 1, i.e., the calcination temperature was 400℃and the rotary kiln rotation speed was 30r/min.
After leaving the rotary kiln for the same time as in example 1, the actual average crystal water content of the kiln-exiting gypsum was 6.32% and the uniformity was 89%.
It can be seen that the gypsum product obtained by the method has obvious deviation between the actual crystal water content and the target crystal water content, and the uniformity is not good enough.
Comparative example 2
The procedure was carried out in the same manner as in comparative example 1 except that the content of the target crystal water was changed to 8.00%.
The calcination conditions were adjusted according to the empirical estimation, as follows: the calcination temperature is 390 ℃, and the rotating speed of the rotary kiln is 32r/min.
The actual average crystal water content of the discharged gypsum was 10.8% and the uniformity was 60% as measured.
It can be seen that the adjustment of the method in the prior art is not flexible enough, the adjustment of the calcination condition can only be guessed, the intermediate process is not fed back and readjusted timely, whether the product meets the requirements can be judged only after the discharged product is obtained, and the defective rate of the product is high.
As can be seen from the comparison of the above examples and comparative examples, the method of the present invention can well meet the requirements of various target crystal water contents; the calcination conditions can be monitored in real time and adjusted in real time in the calcination process, so that the product can reach the set crystal water content within +/-1% when the product is discharged from the kiln; the resulting gypsum product has very good uniformity. The method (comparative example) in the prior art can mainly determine the calcination conditions by experience, can judge whether the crystal water content meets the requirement only after gypsum is discharged from the furnace, can further adjust the calcination conditions, and can not ensure that the adjusted calcination conditions can obtain a better product; in addition, the deviation of the crystal water content of the kiln gypsum obtained by the method in the prior art from the target content is larger, the uniformity is poorer, and the performance in actual use is obviously worse than that of the gypsum obtained by the method in the invention.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (6)
1. A method for controlling the water of crystallization content of a hydrate, comprising:
Monitoring the hydrate by using monitoring points N 1 to N i to obtain a monitoring signal, wherein the monitoring signal comprises the immediate conductivities R 1 to R i of the hydrate, i is an integer more than or equal to 3, and the monitoring points are arranged on the travelling route of the hydrate;
Determining target conductivities R 01 to R 0i corresponding to monitoring points N 1 to N i;
calculating a deviation of the instantaneous conductivity from the target conductivity, adjusting a calcination condition of the travel route based on the deviation;
Calculating the deviation of the instantaneous conductivity from the target conductivity further comprises: further calculating the deviation delta C c between the instant crystal water content at the monitoring point N c and the target crystal water content; and adjusting the calcination conditions of the travel route based on the Δc c, C being an integer between 1 and i;
Establishing a functional relation F (x) between the conductivity of the hydrate and crystal water, calculating the instant crystal water contents C 1 to C i corresponding to the instant conductivities R 1 to R i respectively according to the F (x), and determining the target crystal water contents D 1 to D i corresponding to the target conductivities R 01 to R 0i of the monitoring points N 1 to N i according to the F (x);
The monitoring points N 1 to N i divide the travel route of the hydrate into correction segments, including correction segments L ab determined by adjacent monitoring points, a+1=b, a is an integer between 1 and i-1, b is an integer between 2 and i,
And/or a correction segment L ac determined by non-adjacent monitoring points, a+n=c, n is an integer not less than 2, a is an integer between 1 and i-1;
Wherein the monitoring point N 1 is positioned at the entrance of the travelling route and is used for measuring a monitoring signal comprising the instant conductivity R 1 when the hydrate just enters the calcination environment;
The monitoring point N i is positioned at the outlet of the travelling route and is used for measuring a monitoring signal comprising the instant conductivity R i after the hydrate is calcined.
2. The method of claim 1, wherein determining the target conductivity comprises: the target conductivity R 0i after the hydrate calcination is determined, and then the target conductivities R 02 to R 0i-1 of the monitoring points N 2 to N i-1 are determined through a gradient calculation method according to the initial instant conductivity R 1 and the target conductivity R 0i.
3. The method of claim 1, wherein adjusting the calcination conditions comprises: adjusting the rotary kiln rotation speed to V=V 0+△V,V0 as the current rotary kiln rotation speed, wherein DeltaV is the adjustment quantity, and the signs of DeltaV and DeltaC c are opposite; when DeltaC c is positive, deltaV is negative, namely, the rotary kiln rotates slowly; when DeltaC c is a negative number, deltaV is a positive number, namely the rotary kiln rotates quickly.
4. A method according to claim 1 or 3, wherein the manner of adjusting the calcination conditions further comprises: setting a threshold deviation, wherein the threshold deviation is a determined value less than or equal to delta 10%; performing said adjusting of the calcination conditions when the absolute value of said Δc c is greater than said threshold deviation; when the absolute value of Δc c is not greater than the threshold deviation, no operation is performed.
5. The method of claim 1, wherein the material to be treated comprising the hydrate comprises greater than 50% by weight of dihydrate gypsum.
6. Use of the method according to any one of claims 1-5 for controlling the crystal water content of the discharged gypsum in a gypsum calcination process.
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