SU1627795A1 - Method of determining average moisture content of lumber in cyclic chamber drier - Google Patents

Abstract

The invention relates to the drying of wood and can be used in the woodworking industry and improves the accuracy of the determination. For this, the parameters of the drying agent are measured — tomnofarvpy for dry and wet smelters, the same mass of moisture, 1 additionally, the relative moisture of the piparticles, hrsgch h1, h, weight, pilmat eppacho, sun, and pts, material, rtsgch hip1 h mass, pilomat eppacho, sun, and ppmaterial-h, rtsgch hip1 h mass, pilmat eppacho, and dryness, and ptmaterial, rtsgch hip1 h mass, pilomat eppacho, sunshine, and ptmaterial, rtsgch hip1 h weight, nlpheshchi values determine the mass nyumcht 1- rials in absolutely dry g y pp, the value of which, taking into account i KVHO mass of lumber, is equal to their current moisture content. 1 IM.

Description

The invention relates to the drying of wood, and specifically to a method for determining the average moisture content of sawnwood, and can be used in the woodworking industry.

The purpose of the invention is to improve the accuracy of determining the average humidity.

The drawing shows a graph of the temperature of the dry and wet thermometers in the chamber and the curve of the change in the mass of a pile of lumber over time for a three-stage drying mode.

The method is carried out as follows.

After warming up the lumber set the first stage of drying. The parameters of the drying agent are measured — the temperature by a dry and wet thermometer, as well as the current humidity of materials with a constant discreteness d

 The stack at the first stage of drying decreases asymptotically from the beginning of the Mfl mass to the non-root Mr - the mass of lumber dried to equilibrium moisture with the sawtooth Wp sawmill, corresponding to the parameters TC and T, respectively, TPMHL section of the cvxo iy and working thermometers for the first stage .

Thus, during the first drying stage, the following series of measured process parameters are obtained: a temperature range for a dry thermometer T,

C | TC2) 1) cn temperature range for wet thermometers

N3

-vj

with

SP

RU

my

mg

,, . . Tw . . , TM „(2)

and a series of mass values

mV, m „mg, ..., m;, ..., mp. (3)

The first row (I) is used to determine the average temperature of the cyxoio thermometer.

A number of sawmill stack weight (3) (3) is used to predict the weight of sawn timber, dried in the first stage to equilibrium moisture. In this case, it is assumed that the curve of change in the mass of the pile of sawn materials during the drying process in the first stage is described by solving a second-order differential equation.

System solution (6) is relative

Then one can obtain the following system of equations using the derivation of Mp ;, obtained on the basis of three equilibrium series of values (3)

M

((Mn-M

- .... R,

And Td

t, -tv

where T and T in are constant times; dЈ is the time interval between two measurements of parameters.

System solution (6) is relative

Мр ;, obtained on the basis of three equations, has the form

M,

 m „(YK) (Y;) - (Y ..) 2- (YK) Z

(Y2j - 2Y;). (Y) 2 - (Y2r - 2YK) - (y) 2

Y; n 2;

M0-M ;, 1 1,2,3k-l;

Yi-H - -

Y:

2TtA solution (7) is applied to the points of the row (3) get a number of values

(eight)

M,

M,

 pi p p (K-i) According to this row (8), the average weight of sawn timber Мр, dried to the equilibrium moisture content of wood Wp, corresponding to the parameters Т and Тd at the first step of drying is found

k-1

M

R

1 k-3

M

R; (9)

Then, using the well-known formula

M a.c

100 MP Wp + 100

(YU)

(7)

where is M a.s. - the mass of lumber in a completely dry state, calculate the latter. The value of the absolutely dry mass obtained at the first stage of drying at its initial moment is then used to determine the average current moisture content of lumber by the mass of the stack, both in the remaining time in the first stage and in the other stages of drying, using the expression

50

V. M - M a.s. 1Ppt, M a.c

(AND)

where W is the current average moisture content of lumber; M - the current mass of piles of lumber.

Claims (1)

Invention Formula Method for determining average moisture content of sawn timber in a chamber dryer periodic operation by measuring the parameters of the drying agent and the current mass of sawn timber, characterized in that, in order to improve the accuracy of determination, an equilibrium moisture content of sawn timber is additionally found; Compiled by S. Polnsky Editor Y. Sereda Tehred L. Kravchuk Order 328 Circulation 421 Subscription VNIIPI State Committee for Inventions and Publications under the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, 4/5 Raushsk nab. Production and publishing plant Patent, Uzhgorod, st. Gagarin, 101 materials dried to equilibrium moisture and the found molds determine the weight of the sawn timber in a completely dry state, according to which, taking into account the current weight of sawn timber, the average current humidity is found. W step iu Proofreader I. Muska