JP2725401B2 - Ash meter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ash meter, and more particularly, to equalizing the sensitivity of an X-ray transmission ash meter to a plurality of ash components.

<Prior art> In the paper making process, talc (or clay), calcium carbonate (CaCO ₃ ), titanium oxide (TiO ₂ ) contained in paper
In order to measure the amount of ash, for example, an X-ray transmission ash meter is used.

By the way, as the form of ash content in the above-mentioned paper, there are a form in which two components of talc (or clay) and calcium carbonate or talc (or clay) and titanium oxide are mixed, a form in which talc (or clay), calcium carbonate and titanium oxide are mixed. There is a form in which the components are mixed.

In measuring the ash content, it is desirable that the X-ray absorption coefficient of each component is equalized so that the sensitivity to each component is equal, and measurement can be performed without depending on the abundance ratio of the components.

Therefore, when the two components are mixed, the X-ray spectrum is adjusted by changing the target applied voltage of the X-ray tube, the material of the target, and the like.

<Problem to be Solved by the Invention> However, in the method of adjusting the X-ray spectrum by changing the target applied voltage of the X-ray tube, the material of the target, and the like, when three components are mixed and present, each component may be used. It is difficult to make the absorption coefficients of X-rays equal, and the measurement result depends on the abundance ratio of each component.

The present invention has been made in view of such a point, and an object of the present invention is to provide an ash meter capable of accurately measuring the total ash content without being affected by the abundance ratio of a plurality of components.

<Means for Solving the Problems> The present invention for solving the above problems includes an apparatus unit for generating X-rays, and a detecting unit opposed to the sheet, and measures the amount of ash in the sheet. An X-ray generation mechanism for switching a target application voltage of an X-ray tube in accordance with each of the two ash components so that the sensitivity of each of the two different ash components is equal to each other; A data processing unit for calculating the total ash content from the measurement result obtained by switching the voltage, wherein the total ash content is measured without being affected by the mixing ratio of each ash component. It is.

<Action> In the ash meter of the present invention, the target applied voltage of the X-ray tube is switched in accordance with each of the two components, and the ash is measured with equal sensitivity for each of the two components. Then, based on the measurement results, an operation for removing the influence of the existence ratio of the plurality of components is performed.

As a result, a measurement result that is not affected by the ash content ratio is obtained.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram showing one embodiment of the present invention. In the figure, an X-ray tube 1 and an X-ray detection unit 2 are arranged to face each other with a paper 3 therebetween. X-ray tube 1 target 4
, Output voltages of a plurality of power supplies 6 to 8 are selectively applied as target voltages via a switch 5. The output signal of the X-ray detector 2 for each target applied voltage is applied to the data processor 9. Then, the data processing unit 9 calculates each ash content based on the output signal of the X-ray detection unit 2 for each target voltage.

 The operation of such a device will be described.

By selecting an appropriate material for the target 4 of the X-ray tube 1, for example, talc (or clay) of ash contained in paper, calcium carbonate (CaCO ₃ ), titanium oxide (TiO ₂ )
FIG. 2 shows the relationship between the target applied voltage _VT and the X-ray absorption coefficient μ. In Figure 2, the absorption coefficient of X-ray and mu ₁ target applied voltage and titanium oxide, calcium carbonate (CaCO ₃₎ (TiO ₂₎ is equal sensitivity as V _1, talc (or clay) and calcium carbonate (CaCO ₃ )
There the absorption coefficient of X-ray and mu ₂ target applied voltage becomes equal sensitivity as V _2, the absorption of the talc (or clay) and titanium oxide X-ray target applied voltage (TiO ₂₎ is equal sensitivity as V ₃ the coefficient is μ _3. Then, the _a the absorption coefficient mu of X-ray of talc when applied to the target voltage is V ₁ (or clay), the absorption coefficient of X-ray of titanium oxide (TiO ₂₎ when the target applied voltage is V ₂ mu and is _b, the target applied voltage to the absorption coefficient of X-ray of calcium carbonate (CaCO ₃₎ when the V ₃ and mu _c.

Under such conditions, as shown in the flowchart of FIG. 3, calibration is first performed in a step, measurement is performed in a subsequent step, and calculation is performed in a subsequent step to determine an ash content.

That is, in the calibration step, the target applied voltage V _T
The sequentially switching setting to HV ₁ to HV ₃ in switch 5 obtains an air layer output current I ₁₀ to I ₃₀ by measuring the air layer.

In the measurement step, the target applied voltage V _T sequentially switching setting to HV ₁ to HV ₃ in the switch 5 transmission output currents of the paper 3
Find I _{1 to} I ₃ .

Among these output currents I _{1 to} I ₃ , I _{10 to} I ₃₀ , absorption coefficient μ _{1 to} μ ₃ , μ _{a to} μ _c , and ash content, the amount of talc (or clay) of the paper to be measured is W _Ta , calcium carbonate (CaCO
_Assuming that the amount of ₃ ) is W _Ca and the amount of titanium oxide (TiO ₂ ) is W _Ti , I ₁ = I ₁₀ exp [− {μ ₁ (W _Ca + W _Ti ) + μ _a · w _Ta + α}] (1) ) I ₂ = I ₂₀ exp [− {μ ₂ (W _Ca + W _Ta ) + μ _b · w _Ti + β}] (2) I ₃ = I ₃₀ exp [−Δμ ₃ (W _Ti + W _Ta ) + μ _c. w _Ca + γ｝] (3) Here, α, β, and γ are terms of absorption by paper pulp and moisture, and these absorption terms are determined simultaneously or in advance by performing measurement.

From these equations (1) to (3), the ash content AW (= W
Between the _{Ta + W Ca + W Ti)} , AW {μ 1 / (μ a -μ 1) + μ 2 / (μ b -μ 2) + μ c / (μ c -μ 3)} = A / (μ a −μ ₁ ) + β / (μ _b −μ ₂ ) + C / (μ _c −μ ₃ ) (4) A = ln (I ₁₀ / I ₁ ) −α B = ln (I ₂₀ / I ₂ ) −β The relationship C = ln (I ₃₀ / I ₃ ) −γ is established, and the ash content is determined.

Note that the absorption terms α, β, and γ due to paper pulp and moisture
Is generally given in the form of the total basis weight BW and the moisture percentage MP of the paper.
For this reason, BW includes AW, and the absorption coefficient of paper pulp and moisture at each X-ray energy also changes. Assuming that the absorption coefficients of pulp and water when V _T = HV ₁ are μ _P1 and μ _M1 , respectively, α is α = μ _P1 (BW−AW−BW · MP) + μ _M1 · BM · MP = μ _P1 · BM− (μ _P1 −μ _M1 ) BM ・ MP−μ _P1・ AW, β and γ are similarly β = μ _P2・ BM− (μ _P2 −μ _M2 ) BM ・ MP−μ _P2・ AW γ = become _{μ P3 · BM- (μ P3 -μ} M3) BM · MP-μ P3 · AW.

By substituting these α, β, and γ into equation (4),
AW can be requested. Note that μ _P2 and μ _M2 are pulp and moisture absorption coefficients when V _T = HV ₂ , and μ _P3 and μ _M3 are V _T
= The absorption coefficient of the pulp and moisture when the HV _3.

These series of operations are performed in the data processing unit 9, and each component is accurately measured without being affected by the abundance ratio of a plurality of components.

In the above-described embodiment, an example in which the ash content of the paper is measured has been described. However, by appropriately selecting and selecting the target material and the target applied voltage of the X-ray tube 1, the film material and the alloy film can be measured. Applicable.

Further, the number of power supply switching points is not limited to three, and may be appropriately increased or decreased according to the number of mixed components.

<Effects of the Invention> As described in detail above, according to the present invention, it is possible to provide an ash meter that can accurately measure each component without being affected by the abundance ratio of a plurality of components.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a diagram illustrating the relationship between a target applied voltage _VT and an absorption coefficient μ of X-rays, and FIG. 3 is a flowchart showing the flow of the operation of FIG. is there. DESCRIPTION OF SYMBOLS 1 ... X-ray tube, 2 ... X-ray detection part 3 ... Paper, 4 ... Target 5 ... Switch, 6-8 ... Power supply 9 ... Data processing part

Claims (1)

(57) [Claims] 1. An ash meter for measuring an amount of ash in a sheet, comprising: a device for generating X-rays; and a detection unit opposed to the sheet, wherein each of two different ash components is different from each other. The X-ray generation mechanism in which the target applied voltage of the X-ray tube is switched in accordance with each of the two components so that the sensitivity of the X-ray tube becomes equal, and the measurement results obtained by switching the target applied voltage of these X-ray tubes, An ash meter comprising a data processing unit for calculating the ash content, and measuring the total ash content without being affected by the mixing ratio of each ash component.