JPH02226055A - Ash content meter - Google Patents

Abstract

PURPOSE:To measure ash content accurately without being affected by a blending of three components by determining contents of clay, titanium and calcium by a simultaneous equation with three unknowns obtained for each of through holes and filters to obtain a ash rate signal based on the obtained content value. CONSTITUTION:A motor 8 is driven to turn a filter wheel 7 in a direction of the arrow and as a through hole 7a, a first filter 7b and a second filter 7c are positioned right above an X-ray tube 1 sequentially, X ray energy irradiated to an object 3 to be measured varies corresponding to the positions of the filters. In turn, mass absorption coefficients of clay, titanium and calcium composing ash changes sequentially, with the result that an energy distribution of X rays irradiated from the X-ray tube. Contents of clay, titanium and calcium are determined by simultaneously equations obtained for each of the through holes and filters concerning clay, titanium and calcium thereby obtaining a ash rate signal based on the obtained content value.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an ash meter, and in particular, when the ash content of paper is continuously measured online, clay, titanium, carbonate, etc. are detected in the ash contained in paper. This invention relates to an ash meter that can accurately measure ash even if three components of calcium are present.

<Prior art> Generally, ash is defined as the residue after completely burning paper at a temperature of about 900"C, and is mainly composed of mineral powders such as fillers and pigments added to pulp during paper making. In addition, the addition of ash improves the texture of the paper, improves whiteness and flexibility, and improves printability.In addition, it has great economic benefits as it saves on expensive valves. It has become important to control the ash content, and ash meters that measure the ash content in paper online are now being used to improve the quality of products (Gi) and reduce costs.

FIG. 4 is an explanatory diagram of the configuration of a conventional example of such an ash meter. In the figure, 1 is an X-ray tube, 2 is an electric key box, 3 is a sheet-shaped object to be measured made of, for example, a sheet of paper, and 4 5 is an amplifier that amplifies the ash content signal S sent out from the ionizer 11f2, and 5 is an amplifier that detects the moisture contained in the object to be measured 3 and the weight per unit area (hereinafter referred to as "basis weight"), and calculates the basis weight/moisture content. Quantity signal S2
6 is a calculation unit.

In the conventional ash meter with such a configuration, the X-rays irradiated from the X-ray tube 1 pass through the object to be measured 3 and are expressed by the following formula (1
) attenuates according to the Lambert-Baer law, and then reaches the ionization chamber 2 and is detected. The detection signal becomes an ash content signal S, which is amplified by an amplifier 4, and then
Tsubo! - It is calculated with the basis weight/moisture content signal S2 from the moisture content detector 5 and is output as an ash content signal S3.

1=Io −exp (−i−tχ)−・−(1,
1 Here, ■; Transmitted X-ray dose Io; Incident X-ray dose μ: XI! Absorption coefficient (m2/g) χ; Amount of X-ray absorption substance<g/m') By the way, the ash content in paper is mainly composed of talc, clay, titanium oxide, and calcium carbonate, and these components are It is used in various combinations. With an ash meter that uses the absorption phenomenon of low-energy X-rays, although the detection sensitivity for talc and clay is - time, the absorption coefficients of clay, titanium oxide, and calcium carbonate are different, causing a difference in detection sensitivity. There is.

In order to correct these drawbacks, the characteristic X-rays of Tl (4,5
A sensitive formation analyzer for titanium oxide, clay, etc., using continuous X-rays with energies of KeV) and higher has been developed.

However, these ash meters cannot accurately measure ash, which is a mixture of three components: clay, titanium oxide, and calcium carbonate, because the detection sensitivity of calcium carbonate is about twice that of titanium oxide or clay. The drawback was that it couldn't be done. On the other hand, calcium carbonate, which uses the characteristic X-rays of Ca (3.7KeV) and continuous
A clay-sensitivity fraction analyzer has also been developed. However, these ash meters have a detection sensitivity that is approximately twice as sensitive for titanium oxide as for calcium carbonate and clay, making it difficult to accurately measure ash that is a mixture of three components: clay, titanium oxide, and calcium carbonate. The drawback was that it couldn't be done.

<Problems to be Solved by the Invention> The present invention was made in view of the drawbacks of the conventional examples, and its problem is that of clay and titanium oxide.

An object of the present invention is to provide an ash meter capable of accurately measuring ash content regardless of the composition of these three components even if the three components, lucium and carbonate, are contained in an object to be measured.

According to the present invention, X-rays emitted from an X-ray tube are transmitted through a sheet-shaped object to be measured and attenuated, and then detected in an ionization chamber.
After the detection signal is amplified, a predetermined calculation is performed in a computing unit with the basis weight/moisture content signal from the basis weight/moisture content detector to produce an ash content signal indicating the percentage of ash contained in the object to be measured. In the ash content meter, a filter wheel having a through hole, a first filter, and a second filter disposed on the circumference and disposed between the X-ray tube and the M$lJ body to be measured; and a motor that rotates the X-ray tube and sends a synchronization signal to the arithmetic unit, and when the motor rotates and the through hole, the first filter, and the second filter are sequentially positioned directly above the X-ray tube, these filters The X-ray energy irradiated to the object to be measured changes in accordance with the position of The above-mentioned problem is solved by determining the contents of clay, titanium, and calcium from three-dimensional simultaneous equations obtained for each through-hole and filter, and determining the ash content signal based on the contents.

<Example> Hereinafter, the present invention will be described in detail using the drawings. 1st
Figure (A) is an explanatory diagram of the configuration of an embodiment of the present invention. In the figure, the same symbols as in Figure 4 are used with the same meanings, and repeated explanations here will be omitted. Further, 7 is a filter wheel, and 8 is a motor that rotates the filter wheel 7 at a constant cycle and sends a rotation synchronization signal to the calculator 6. Second
Figure i□□□ is a view of the filter wheel 7 viewed from the upper side of Figure 1 (i.e., from the side of the object to be measured 3), in which 7a is a through hole, 7b is a first filter, and 7c is a second filter. It is. On the other hand, FIG. 3 is a diagram showing the relationship between X-ray energy and mass absorption coefficient. In this figure, the mass absorption coefficient (μ) changes depending on the X-ray energy (E), but titanium oxide, calcium carbonate, and
Alternatively, clay exhibits a larger absorption coefficient, indicating that it absorbs X-rays more easily. Furthermore, calcium carbonate and titanium oxide change rapidly after reaching a certain energy level (the so-called absorption edge). The operation of the embodiment of the present invention will be described below, based on the consideration of the relationship between X-ray energy and mass absorption coefficient.

In the embodiment of the present invention having the configuration shown in FIGS. 1 and 2, the motor 8 is driven to rotate the filter wheel 7 in the direction of the arrow in FIG. When the filter 7c is located directly above the primary X-ray tube 1, the X-ray energy irradiated to the object to be measured 3 changes, and the mass absorption coefficient of the clay constituting the ash is μC.

It changes to μC2+μii3. Similarly, the mass absorption coefficient of titanium constituting the ash is μm++μt2. μt3, and the mass absorption coefficient of the clay that makes up the ash is μC++μ
It changes to C2+μc3. Further, the through hole 7a of the filter wheel 7, which is irradiated from the X-ray tube 1, and the first filter 7
b, or the X-rays that do not pass through the second filter 70 pass through the fixed object 3 and are attenuated according to the Lambert-Baer law as shown in equation (1) above, and then reach the separation 2 and are detected. Ru. The detection signal becomes an ash content signal S1, which is amplified by the Ang 4, and then calculated with the basis weight/moisture content signal S2 from the basis weight/moisture content detector 5, and is output as an ash content signal S3. Note that a rotation synchronization signal is sent from the motor 8 to the calculator 6, so that the calculator 6 can determine which filter is selected. Therefore, when clay, titanium 1, and calcium are contained in the measured object 3, respectively, χa (%), χt (%), and χC (%), the through hole 7a of the filter wheel 7 is irradiated from the X-ray tube 1. , the amount of incident X-rays passing through the first filter or the second filter 7c and entering the object to be measured 3 changes as I+, ■2+13, and the ash content signal S3 is obtained as sV, SV2, and Sv. The formula below (2
) to (4) are established.

Sv+ =I+ ・exp ((μa+ ・χa〉μ豐1 ・χ でμc1 ・χc))・Old・・(2) S
y2=12 ・exp (−(μC2・χa×μt2
・χ to 10 μc2 ・χc))・・・・・・(3) SV3
=13 ・eXP ((jAa:i
・χ a.

10 μt ・χ t 10 μc 3
・χ c ) ) ...... (4) Above (
In formulas 2) to (4), μa++μa21 μiL
3 + AL t l * μ (2+
μt3. If μC1μC2+μc3 is determined in advance, the clay, titanium, and calcium contents χa (%), χt (%), and χC (%) can be calculated by solving the ternary simultaneous equations (2) to (4) above. ) is determined, and the ash content signal is determined based on these content rates.

That is, the motor 8 is driven and the filter boiler is in the second position.
The through hole 7a and the first filter 7b rotate in the direction of the arrow in the figure.
, when the second filters 7C are successively positioned directly above the X-ray tube 1, the X-ray energy irradiated to the object to be measured 3 changes corresponding to the positions of these filters, and the clay and titanium constituting the ash content change.

The mass absorption coefficients of calcium and calcium change sequentially, and as a result, the energy distribution of the X-rays irradiated from the X-ray tube changes, and the three-dimensional simultaneous equations obtained for each through hole and filter for the clay, titanium, and calcium. The respective content rates of clay, titanium, and calcium are determined from the above, and the ash content signal is determined based on the content rate.

<Effects of the Invention> According to the present invention as explained in detail above, even if the three components of clay, titanium oxide, and lucium carbonate are contained in the object to be measured, the results are determined by the composition of these three components. This makes it possible to accurately measure ash content (concentration of each component of ash, total ash content, etc.) without any problems.

That is, the filter wheel 7 rotates in the direction of the arrow in FIG.
When filters C are successively positioned directly above the X-ray tube 1, the X-ray energy irradiated to the object to be measured 3 changes depending on the position of these filters, and the mass absorption of clay, titanium, and calcium that make up the ash content changes. The coefficients change sequentially and as a result, the above
The energy distribution of the X-rays irradiated from the ray tube changes, and from the ternary simultaneous equations obtained for each through hole and filter for the clay, titanium, and calcium, the clay,
The content of titanium and calcium is determined, and the ash content signal is determined based on the content.As a result, the ash content can be determined accurately without being influenced by the composition of the three components: clay, titanium oxide, and lucium carbonate. be able to measure.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the main part configuration of the embodiment of the present invention, Fig. 2 is a diagram showing the filter wheel, Fig. 3 is a diagram showing the relationship between mass absorption coefficient and X-ray energy, and Fig. 4 is a diagram of the conventional example. FIG. 2 is an explanatory diagram of the main part configuration. 1...X-ray tube, 2...key box, 3...
...Object to be measured, 4...Amplifier, 5...
... Basis weight/moisture content detector, 6... Arithmetic unit, 7
...Filter wheel, 8...Motor Fig. 1 Fig. 3 E (X Ueji f11.-key) Z- Fig. 4

Claims (1)

[Claims] The X-rays emitted from the X-ray tube pass through the sheet-shaped object to be measured and are attenuated, and then detected in the ionization chamber. After the detection signal is amplified, the basis weight/moisture content detector outputs the In an ash meter that performs a predetermined calculation on a moisture content signal in a calculator to obtain an ash content signal indicating the percentage of ash contained in the object to be measured, a through hole, a first filter, and a second filter are arranged in a circumferential manner. A filter wheel disposed above and between the X-ray tube and the object to be measured, and a motor that rotates the filter wheel and sends a synchronization signal to the arithmetic unit, and the motor rotates. When the through hole, the first filter, and the second filter are sequentially located directly above the X-ray tube, the X-ray energy irradiated to the object to be measured changes depending on the position of these filters, and the ash content is reduced. The mass absorption coefficients of the clay, titanium, and calcium that constitute the clay, titanium, and calcium change sequentially, and the respective contents of the clay, titanium, and calcium are determined from the ternary simultaneous equation obtained for each through hole and filter for the clay, titanium, and calcium. The ash content meter is characterized in that the ash content signal is determined based on the determined content rates.