DE1773808C3 - Moisture measuring arrangement for a moving web of material - Google Patents

Description

Riiilbahn at the wet end has high accuracy to humidification via the Leituag.51 supplies and given and thereby unforeseen changes in if indicates the measuring device for the reason of the material web to be produced to be taken into account. weight on the dry end, the measuring device for To lose this task, a moisture level is the basis weight on the wet end and the moisture level arrangement of the type described in the introduction are also suitable according to the invention constructed in such a way that one is also connected to the other, so that the synchronous sampling of the Barometric width measuring device enabled both on the wet and web by each of the measuring devices is also provided at the dry end of the web.

and that in the computing device for determining the output of the measuring device 45, which the

the moisture content is the weight per unit area of the paper based on the instantaneous mass per unit area

dry and at the wet end with the one indicated there at point A , which indicates both the moisture and

determined web speed and web width biscuit and fiber content at this point

is multiplied. closes, is added to the mass flow computer S3

The present invention thus provides a moisture guide. Using a conventional width measuring device

activity measuring arrangement, which is a very precise and 15 direction 55 is the current width of the web

reliable determination of moisture content 36 measured and displayed at point A; the pulp

at the wet end, all influencing signals are also fed to the computer 53.

sizes or variables, e.g. B. the orbit speed.

speed and the orbital dimensions are indicated in full by 57, is used for generation

be sighted. 20 of a signal. The speed of the web 36 on

Below the invention in connection with the point A is made with a tachometer 57 or

with the drawing on the basis of a preferred embodiment of another known speed measuring device

management example explained. direction measured and displayed. The outcome of the

The single figure shows in a block diagram speed display device 57 is also with

the moisture measuring device according to the invention. »5 connected to the mass flow computer 53.

Within the dash-dotted box 10 are the computer 53 can either em analog or

the various elements are shown schematically. be a digital computer, the specific elements of which are known per se in a conventional Fourdrinier paper machine. The computer 53 is the preferred setting process, namely an analog computer and calculates from the flow 20, a Fourdrinier screen section 22, a press 30 different input signals, the following track section 24, a dryer section 26, an expansion of the mass flow rate per unit of time: rer press section 28 and a final dryer section βψ. ς. μ /

30. The paper source material that goes into the fabric - MF _A - - —-——

run 20 is fed in, is in the Fourdrinier- ^ i

Section 22 is formed into a 35 _{m of} the MF _4, the mass flow rate per unit of time at th mat, schematically indicated by 32. Adhering to the mat 32 _{A BWa} the basis weight at A, S _A and W _A Entwash is on the press section 24 ausgetrie- speaking, the speed and the width of the ben so that a self-supporting web is formed 34 _B ahn ^ ^ _{un £} jr _{e n} constant factor is that thereafter in steam dryers waste _the output of the measuring device 47 for the

Sections 26 and 3β and in the press section 28 weighted at the moist end, which is instantly dried and pressed again. The web 36 is _Icne j \ 4 _asse per unit area of the paper at the on leaving the dryer section 30 the finished _{Ste c} jj _{e Ad} IGT is the Massendurchflußrechner recycled paper, which performs other _{59 applied} subsequently. Conventional width gauge processing stages, e.g. B. cropping, over _{t 61 m, d} j _{e SST} width of the web 34 at the location C. pull u. Like. Can pass through. 45 _The latitude signal is also fed into the calculator

Feed in due to the nature of the papermaking process. A second Geschwindigkeitsmeßvorrichist the critical moisture content at the point C _{mng 63 measures the} speed of the web 34 where the web 34 is relatively high and can not _{c place also} (Ji is ₆₅₆₈ signal supplied to the mass flow exactly and directly measured by methods known flow computer 59th

will; the final moisture content at the dry 5 ° _The mass flow computer 59 corresponds in the kenen end, however, ie at point A of the web 36, structure to the computer 53 and calculated from the Einist relatively low and can be measured with known output signals according to the following equation of the mass methods and subsequently to the in-flow per unit of time at point C: direct determination of the moisture content on

wet end to be used 55 ^ f _ ^ SiL ^i: LS. _;

The device for determining the humidity ^f K ₁

SSSSX ÄÄTilÄS; in the M. the mass flow rate ^ rc> Time unit at

on which preferably a C, BW _C which scans across the web is the basis weight at C S _c : and V _c die

Beta radiation measuring device of known Konstnik- 60 speed and width of the web bet CJmd

Son and a measuring device 47 for the basic K _{1 are} a constant factor. D * ^^ ⁸ ^

weight at the wet end, also one across the MF _A , MF _C the computers 53 and S9 become one

Orbit scanning beta radiation measuring device. third computer 65 supplied. y-irhmine

The measuring devices can be equipped with a corresponding

the Profilmittelunieinrichtang be provided. 6 ₅ is ei « ^^^^^^ Z ^^

At the dry end there is also a moisture structure ω at point A , which makes the

Measuring device 49 of known type is provided, which has a percentage of moisture content shows an output signal proportional to the percentage position. This moisture content signal

is fed together with the output signals MF _A , MF _{C to} the computer 65, which uses the following equation to calculate the moisture content of the web at point C:

M =

MFc-MFa [I- _mj

MFa [I-

m \ TÖÖj

Water / kg fiber, and m is the percent moisture at the dry end A.

According to a further preferred embodiment, the computer is used to solve the equation

MFc-MFa 1-

M =

\ 100 /

MFc

100

in the M is the water content at C, expressed in kg. In this case, M is the water content of the paper at C, expressed as a percentage of moisture.

1 sheet of drawings

Claims (2)

■ Γ ί-3 I <* 2 Paper is not completely free from moisture, as claims: this could be inferred from the name. During the Fourdrinier papermaking process, 1. Moisture measuring arrangement for one found that in the area of the presses that follow the moving material web, which follows the forming section during passage 5, the fiber binding process begins between a first and a second station and its extent is greatly withdrawn from the freucnng fire and its The moisture content of the web at this point affects wrra. It has also been found that the high t eucn grammage measuring device and one activity content at the wet end near the rres web speed measuring device at the wet io sen section of the moisture content is not directly and at the dry end as well as a damp - and can be measured exactly, keitsmeßeinrichtung at the dry end of the web In the USA.-Patent 3 260 642 and the basis of a laying device connected to the measuring devices and the method for the indirect calculating device is determined, characterized by the determination of the moisture content on the wet that additionally a web 15 end is described in which the basis weight is provided at the width measuring device (55,61) both at the wet wet end, the basis weight at the dry end, as well as at the dry end of the web and the moisture content at the dry end, and that in the computing device for measuring; and from this the surface moisture content at the wet end is determined in a computer of the mood of the moisture content, weight at the dry and at the wet end each- * » In one embodiment, the computer uses the relationship expressed by the following formula with the path speed determined there : speed and web width is multiplied. , _f \ 2. Moisture measuring arrangement according to An W - D j 1 - J spoke 1, characterized in that the u = - ^ moisture measuring device (49) is one of the percent- »5 μ · ' The signal (m) corresponds to the actual moisture of the web, and that the product of where M is the moisture content at the wet end, W basis weight, web speed and web is the basis weight at the wet end, D is the basis width at the dry end multiplied by the weight at the dry end , c the percentage moisture (1 - m / 100) is multiplied. 3 <> activity content is at the dry end. The aforementioned U.S. Patent also teaches that The result obtained in this way must be corrected by a correction factor derived from the difference in the speed of the web on the wet and on the dry The invention relates to a moisture 35 end being formed. This takes into account the longitudinal dimensioning arrangement for a moving material dimensional change in the web due to the stretching path which is drawn from the speed differences in a second station when passing between a first and a second station. their moisture content at the wet end with the aid of US Pat. No. 3,073,153 is still available one basis weight measuring device each and one device each for determining the breadcrumbs web speed measuring device at the wet end and at the wet end of a moving end known at the dry end as well as a moisture measuring paper web. The known device has establishment at the dry end of the web in one for this purpose at the dry and at the wet end one basis weight measuring device is determined in each case with a computing device connected to the measuring devices. A known arrangement 45 device and a web speed measuring device This type is used in particular for monitoring and, at the dry end, also a moisture control of the moisture content of a paper web tigkeitsmeßeinrichtung on. The from the Messeinrich in their manufacture. The signals emitted are sent to an evaluation In the Fourdrinier papermaking process, it is also fed to the device in which the moisture content in other papermaking processes, it is desirable to remove 50 at the wet end of the web and often required the moisture content at the can. The evaluation of the individual measurable variables has to be determined at the end. The expression "moist- follows in a manner similar to that in context keitshalt am wet end ", as it is used in the case of the above-mentioned known device of the invention, refers to the device was described, but with the difference the moisture content at one point on the paper with the web speed measuring devices manufacturing process, at which the moisture content to the speed ratio on the wet and is higher than that he can directly with sufficient accuracy - at the dry end corresponding correction factor speed is measured by conventional devices, with which the basis weight is then determined can be. In particular and in connection with the wet end of the web is multiplied, 60 It has now been found that the dimensions of the the moisture hair at the wet end on the paper web when passing through the presses and the Moisture content at a point after the four-dryer sections not only depend on the stretching that drinierabschnitt and in front of the point at which the paper causes the speed differences, being passed through the Trocküeräbschnitte. Generally there will be a flow, but that also a shrinkage the "dry end" refers to the portion of the 65 due to the heat in the dryer sections Paper manufacturing process in which the paper occurs dry has been net, d. H. Water up to a certain The invention is based on the object low value has been removed, although the moisture content of a moving material