CN112996166A

CN112996166A - Resonant cavity for microwave puffing of gradient wood and preparation method of gradient wood

Info

Publication number: CN112996166A
Application number: CN202110201062.9A
Authority: CN
Inventors: 贺霞; 邓曙光; 周理; 李曼; 周文雪; 陆志强
Original assignee: Hunan City University
Current assignee: Hunan City University
Priority date: 2021-02-23
Filing date: 2021-02-23
Publication date: 2021-06-18
Anticipated expiration: 2041-02-23
Also published as: CN112996166B

Abstract

The invention relates to the technical field of wood treatment, and particularly discloses a resonant cavity for microwave puffing of gradient wood, which comprises a main resonant cavity and at least two groups of feed-in ports, wherein the two groups of feed-in ports are arranged along the axial direction of the main resonant cavity; the microwave power of the two groups of feed inlets is different. The invention utilizes the feed-in port groups with different microwave powers to carry out microwave radiation on the wood, changes the expansion rate of different parts of the wood, and forms gaps with gradually changed sizes, thereby changing the permeability of different parts of the wood, and leading the functional material to be impregnated in the later period to embody different effects on the same wood.

Description

Resonant cavity for microwave puffing of gradient wood and preparation method of gradient wood

Technical Field

The invention relates to the technical field of wood treatment, in particular to a resonant cavity for microwave puffing of gradient wood and a preparation method of the gradient wood.

Background

The microwave drying of the wood is to enable the wood to generate heat integrally by a uniform microwave field, so that the temperature gradient and the water content gradient in the drying process can be eliminated, wherein the water is simultaneously discharged from inside to outside to enable the expansion and contraction coefficients of the wood to be basically consistent, thus the wood can avoid the losses of deformation, cracking, drying, carbonization and the like to the maximum extent in the drying process, and the yield of the wood can be improved. Compared with the traditional drying mode, the microwave drying device has the advantages of high drying speed, energy conservation, high production efficiency, uniform drying, clean production, easy realization of automatic control, improvement of product quality and the like, and is easy to control in the microwave drying process; and no noise and harmful gas emission, and belongs to the environment-friendly drying technology. The microwave heating drying makes the internal temperature of the wood higher than the surface. The outward pressure difference is formed in the wood, and the surface migration of moisture is accelerated, so the microwave drying speed of the wood is 20-30 times faster than the convection drying speed. Compared with far infrared and steam drying, the energy consumption is reduced by more than 25%. The microwave drying of the material can make the temperature inside the wood higher than 60 ℃, and parasitic ova in the wood can be quickly killed, thereby achieving the effects of moth prevention and mildew prevention. The proper microwave heating speed is required for various woods with different properties to achieve the optimal process condition, and the better benefit can be obtained.

The invention patent with the publication number of CN103108425B discloses a cylindrical three-port feeding resonant cavity for wood microwave pretreatment, which can improve the uniformity of the temperature distribution of wood microwave pretreatment, but does not consider the diversity of wood processing, and the single puffing rate of wood is difficult to satisfy the requirement of wood subsequent processing.

Disclosure of Invention

In order to solve the technical problem of single wood expansion rate, the invention provides the resonant cavity for microwave expansion of the gradient wood. The specific technical scheme is as follows:

a resonant cavity for microwave puffing of graded wood comprises a main resonant cavity and at least two groups of feed inlet groups, wherein the two groups of feed inlet groups are arranged along the axial direction of the main resonant cavity; the microwave power of the two groups of feed inlets is different.

Further, the resonant cavity comprises a main resonant cavity, a first feed-in port group, a second feed-in port group and; the first feed inlet group, the second feed inlet group and the third feed inlet group are arranged along the axial direction of the main resonant cavity, and the microwave power is gradually increased.

Further, the microwave power of the first feed inlet group is 5-15 kw; the microwave power of the second feed inlet group is 15-25 kw; the microwave power of the third feed inlet group is 25-35 kw.

Further, the feed port group comprises at least three feed ports, and the three feed ports are arranged along the radial direction of the main resonant cavity.

Further, the feed ports between adjacent feed port groups are arranged in a staggered manner in the radial direction of the main resonant cavity.

The invention also provides a preparation method of the gradual change type wood, which comprises the following steps:

s1, adjusting the water content of the wood to enable the water content of the wood to be gradually increased from a first end to a second end;

s2, performing microwave treatment on the wood by using the resonant cavity of any one of claims 1 to 5, so that the end with higher water content of the wood is close to the feed inlet group with higher microwave power, and obtaining the gradual change type wood.

Further, the adjusting of the moisture content of the wood in the step S1 includes:

s101, dividing wood into at least two sections;

s102, immersing the divided first section of wood into a modification liquid A, pressurizing the modification liquid A to 1.5-1.8 MPa, and keeping for 1-2 hours, wherein the modification liquid A comprises 20-35 parts by weight of urea, 15-25 parts by weight of methacrylic acid and 15-25 parts by weight of polyvinyl alcohol;

s103, immersing the divided second section of wood into the modification liquid A, pressurizing the modification liquid A to 2.5-2.8 MPa, and keeping for 3-4 hours.

Further, before the step S102, the whole wood is immersed into the modifying liquid B, the modifying liquid B is pressurized to 2.2 MPa-2.5 MPa, and the pressure is maintained for 0.5-1 h; wherein the modification liquid B comprises 15-20 parts of urea, 5-8 parts of cocamidopropyl betaine, 6-8 parts of acrylamide, 10-20 parts of sucrose ester and 200 parts of deionized water in parts by weight.

Has the advantages that: 1. the invention provides a gradient type resonant cavity for microwave puffing of wood, wherein a plurality of feed inlet groups are axially arranged on a main resonant cavity, and different microwave powers are set for the feed inlet groups, so that the puffing rates of different parts of the wood are different, and the wood with the gradually-changed puffing rate is formed; and different bulking rates make the inside clearance size of timber change to the permeability that makes each position of timber different, make the later stage impregnate functional material, can embody different effects on same root timber.

2. The invention provides a method for preparing gradual change type wood, which comprises dividing wood into multiple sections, respectively immersing the divided sections into a modification solution A, changing the immersion condition, using the modification solution A to perform esterification reaction with hydroxyl in wood fiber, thereby consuming hydrophilic hydroxyl, changing the water content of wood, and changing the water content of different parts of wood by changing the pressure environment and holding time of each section of wood; and the higher the expansion rate of the wood, the larger the expansion degree of the wood, the lower the water content, the deeper the microwave penetrates when the microwave treatment is carried out, and the parts with high wood expansion rate are ensured by making the water content of different parts of the wood different, and the deeper the microwave penetrates, thereby ensuring the uniformity of the prepared gradual-change wood.

Drawings

FIG. 1 is a schematic structural diagram of a resonant cavity in example 1 of the present invention;

FIG. 2 is a schematic radial cross-sectional view of a resonator in example 1 of the present invention;

fig. 3 is a schematic view of the inside of the gradually-changed wood after microwave puffing in example 1 of the present invention.

Reference numerals: 1. a main resonant cavity; 101. a first feed port group; 102. a second feed-through group; 103. a third group of feed-throughs.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention; the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; furthermore, unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, as they may be fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example 1

As shown in fig. 1, the present embodiment discloses a resonant cavity for microwave puffing of gradually-changed wood, which includes a main resonant cavity 1, and a first feed inlet group 101, a second feed inlet group 102, and a third feed inlet group 103, where the first feed inlet group 101, the second feed inlet group 102, and the third feed inlet group 103 are respectively arranged along an axial direction of the main resonant cavity 1 and are respectively communicated with the main resonant cavity 1, and microwave powers of the first feed inlet group 101, the second feed inlet group 102, and the third feed inlet group 103 are gradually increased.

When the microwave puffing is carried out on the wood, the wood is placed in the main resonant cavity 1, microwave energy is fed in through the three feeding ports, electromagnetic loss caused by interaction of the microwave and moisture in the wood is converted into heat energy, and therefore the wood is heated and dried. In the process that moisture is separated from the wood, gaps are generated inside the wood, and the swelling of the wood is realized. In order to obtain the gradually-changed wood, in the present embodiment, the microwave powers of the first feeding port group 101, the second feeding port group 102, and the third feeding port group 103 are gradually increased, the moving speed of the moisture in the wood is increased by increasing the microwave power, so as to improve the bulking degree of the wood, and the gradually-changed wood is obtained through the feeding port groups with different microwave powers. Because the obtained gradual change type wood has different internal expansion rates, the gradual change type wood can have different permeability when other functional materials are impregnated in the subsequent process, and different effects can be embodied on the same wood. For example, during post-dyeing, less dye is penetrated into the wood part irradiated by small microwave power, and the color is lighter; the wood parts irradiated by high microwave power have more dye and darker color.

Specifically, in the present embodiment, the microwave power of the first feed port group 101 is set to 10 kw; the microwave power of the second feed set 102 was set to 20 kw; the microwave power of the third group of feed openings 103 is set to 30 kw. Each feed port group comprises three feed ports, the feed ports between the same feed port group are distributed at an interval of 120 °, and the feed ports between the adjacent feed port groups are staggered in the radial direction of the main resonant cavity 1, as shown in fig. 2. The internal structure of the gradual change wood obtained after the wood is dried by using the resonant cavity is shown in fig. 3.

In this embodiment, the feeding ports with different powers are arranged to dry the wood respectively, so that the water moving speeds of different parts of the wood are different, gaps with different sizes are formed in the wood, and the gradually-changed wood is obtained. The obtained gradual change type wood can show different effects on one wood on the premise of not damaging the whole structure of the wood when other functional materials are subsequently impregnated.

It should be understood that the technical solution protected by the present invention is not limited to the resonant cavity with three feeding port sets, and all the technical solutions for obtaining the graded wood by using the present invention with different microwave power radiation fall within the protection scope of the present invention.

Example 2

This example discloses a method for preparing a graded wood, in which the resonant cavity of example 1 is used to dry wood, and specifically the method for preparing a graded wood is as follows.

and S2, performing microwave treatment on the wood by using the resonant cavity in the embodiment 1 to enable the end with higher water content of the wood to be close to the feed inlet group with lower microwave power, so as to obtain the gradual change type wood.

In this embodiment, the resonant cavities in embodiment 1 are used to radiate wood with different microwave powers, and the higher the microwave power, the higher the puffing rate of wood, and therefore the larger the volume expansion degree of wood. In this embodiment, through the water content that changes the different positions of timber for the higher one end of water content is close to the lower feeding port group of microwave power, and the lower one end of water content is close to the higher feeding port group of microwave power, and the water content is higher, and the microwave pierces through deepening, thereby guarantees to the holistic microwave treatment of timber, improves popped homogeneity.

Example 3

This example discloses a method of adjusting the moisture content of wood on the basis of example 2, which comprises

S101, dividing the wood into at least two sections, immersing the whole wood into a modification liquid B, pressurizing the modification liquid B to 2.2MPaMPa, and keeping for 0.5 h; wherein the modified liquid B comprises 15 parts of urea, 5 parts of cocamidopropyl betaine, 6 parts of acrylamide, 10 parts of sucrose ester and 100 parts of deionized water in parts by weight;

s102, immersing the divided first section of wood into a modification liquid A, pressurizing the modification liquid A to 2.8MPa, and keeping for 4 hours, wherein the modification liquid A comprises 35 parts by weight of urea, 25 parts by weight of methacrylic acid and 25 parts by weight of polyvinyl alcohol;

s103, immersing the divided second section of wood into the modification liquid A, pressurizing the modification liquid A to 1.5MPa, and keeping for 1 h.

In the embodiment, the modifying liquid B is used for removing protein and grease contained in the wood, so that the modifying liquid A can be conveniently infiltrated, and the modifying liquid A and hydroxyl in wood fibers are subjected to esterification reaction, so that hydrophilic hydroxyl is consumed, and the water content of the wood is changed; the water content of different parts of the wood is different by changing the pressure and the time for immersing the first section of wood and the second section of wood in the modifying liquid.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several equivalent substitutions or obvious modifications can be made without departing from the spirit of the invention, and all the properties or uses are considered to be within the scope of the invention.

Claims

1. A resonant cavity for microwave puffing of gradual change type wood is characterized in that: the feed-in device comprises a main resonant cavity (1) and at least two groups of feed-in ports, wherein the two groups of feed-in ports are arranged along the axial direction of the main resonant cavity (1); the microwave power of the two groups of feed inlets is different.

2. The resonant cavity for microwave puffing of graded wood as claimed in claim 1, wherein: the resonant cavity comprises a main resonant cavity (1), a first feed inlet group (101), a second feed inlet group (102) and a third feed inlet group (103); the first feed inlet group (101), the second feed inlet group (102) and the third feed inlet group (103) are arranged along the axial direction of the main resonant cavity (1), and the microwave power is gradually increased.

3. The resonant cavity for microwave puffing of graded wood as claimed in claim 2, wherein: the microwave power of the first feed inlet group (101) is 5-15 kw; the microwave power of the second feed inlet group (102) is 15-25 kw; the microwave power of the third feed inlet group (103) is 25-35 kw.

4. The resonant cavity for microwave puffing of graded wood as claimed in claim 1, wherein: the feed port group comprises at least three feed ports, and the three feed ports are arranged along the radial direction of the main resonant cavity (1).

5. The resonant cavity for microwave puffing of graded wood as claimed in claim 4, wherein: the feed ports between adjacent sets of feed ports are staggered in the radial direction of the main resonator (1).

6. A method for preparing gradual change wood is characterized in that: the method comprises the following steps:

s2, performing microwave treatment on the wood by using the resonant cavity of any one of claims 1 to 5, so that the end with higher water content of the wood is close to the feed inlet group with lower microwave power, and obtaining the gradual change type wood.

7. The method of claim 6, wherein the step of preparing the gradient wood comprises: the process of adjusting the moisture content of the wood in the step S1 includes:

s101, dividing wood into at least two sections;

s102, immersing the divided first section of wood into a modification liquid A, pressurizing the modification liquid A to 2.5-2.8 MPa, and keeping for 3-4 h, wherein the modification liquid A comprises 20-35 parts by weight of urea, 15-25 parts by weight of methacrylic acid and 15-25 parts by weight of polyvinyl alcohol;

s103, immersing the divided second section of wood into the modification liquid A, pressurizing the modification liquid A to 1.5-1.8 MPa, and keeping for 1-2 hours.

8. The method for preparing a graded wood according to claim 7, wherein: before the step S102, the whole wood is immersed into the modifying liquid B, the modifying liquid B is pressurized to 2.2 MPa-2.5 MPa, and the pressure is kept for 0.5-1 h; wherein the modification liquid B comprises 15-20 parts of urea, 5-8 parts of cocamidopropyl betaine, 6-8 parts of acrylamide, 10-20 parts of sucrose ester and 200 parts of deionized water in parts by weight.