CN111438781A - Aldehyde-reducing heat treatment process and continuous energy-saving aldehyde-reducing heat treatment kiln - Google Patents
Aldehyde-reducing heat treatment process and continuous energy-saving aldehyde-reducing heat treatment kiln Download PDFInfo
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- CN111438781A CN111438781A CN202010355825.0A CN202010355825A CN111438781A CN 111438781 A CN111438781 A CN 111438781A CN 202010355825 A CN202010355825 A CN 202010355825A CN 111438781 A CN111438781 A CN 111438781A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
- B27K5/00—Treating of wood not provided for in groups B27K1/00, B27K3/00
- B27K5/0085—Thermal treatments, i.e. involving chemical modification of wood at temperatures well over 100°C
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
- B27K5/00—Treating of wood not provided for in groups B27K1/00, B27K3/00
- B27K5/0085—Thermal treatments, i.e. involving chemical modification of wood at temperatures well over 100°C
- B27K5/009—Thermal treatments, i.e. involving chemical modification of wood at temperatures well over 100°C using a well-defined temperature schedule
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D13/00—Apparatus for preheating charges; Arrangements for preheating charges
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
- F27D17/004—Systems for reclaiming waste heat
Abstract
The invention relates to the technical field of plate aldehyde reduction, and discloses an aldehyde reduction heat treatment process, which comprises the following steps: putting the artificial board into an aldehyde-reducing heat treatment kiln for heat treatment; placing the artificial board after heat treatment into a health-preserving balance chamber for preserving; the heat treatment mode adopts a preheating-heating-constant temperature multi-stage aldehyde reduction mode, the constant temperature is 110-130 ℃, and the constant temperature time is 1-4 h; the preheating temperature is 50-80 ℃, and the preheating time is 0.5-6 h. The continuous energy-saving and aldehyde-reducing heat treatment kiln comprises a preheating kiln section, an aldehyde-reducing kiln section and a balance kiln section which are connected in sequence, wherein the preheating kiln section is provided with a feed inlet, and the balance kiln section is provided with a discharge outlet; the aldehyde reduction kiln section is provided with a heat supply assembly, an airflow conveying assembly is arranged between the balance kiln section and the preheating kiln section, and the airflow conveying assembly is used for conveying airflow of the balance kiln section to the preheating kiln section. By adopting the technology of the invention, the effect of reducing aldehyde can be effectively achieved, meanwhile, the treatment period of reducing aldehyde is short, and the production efficiency is improved.
Description
Technical Field
The invention relates to the technical field of plate aldehyde reduction, in particular to an aldehyde reduction heat treatment process and a continuous energy-saving aldehyde reduction heat treatment kiln.
Background
The adhesive used in the artificial board comprises urea-formaldehyde resin as the main component. The urea-formaldehyde resin can continuously release formaldehyde to the surrounding environment when the environmental conditions such as temperature, humidity and the like change, the release period can reach more than ten years, and the urea-formaldehyde resin is a main body for causing formaldehyde pollution in indoor air. Therefore, it is important to reduce the formaldehyde content in the board.
Patent publication No. CN102041890A discloses a method for manufacturing a composite floor board with low formaldehyde emission by heat treatment. The composite floor is put into a heat treatment box to be heated at the temperature of 60-110 ℃ for 8-96 hours. The long-time medium-low temperature heating mode is adopted, so that the problems of long treatment period and poor aldehyde removal effect exist.
In the process of reducing aldehyde of the artificial board by adopting heat treatment, the artificial board is mostly placed in the box body for heat treatment, however, the box body used as a heat treatment chamber has the problems of low treatment capacity, high energy consumption and long treatment period of the artificial board. At present, a kiln body specially used for aldehyde reduction heat treatment does not appear, and the kiln body mainly used for processing artificial plates at present is a thermal modification kiln, a drying kiln and the like.
Patent publication No. CN207594014U discloses a wood thermal modification kiln. In the technical scheme of the patent, the plate is discharged out of the kiln body after being subjected to heat treatment and cooling, and residual airflow in the kiln body still has heat, but the residual airflow is not effectively utilized, so that waste is caused. When the next batch of plates need to be subjected to heat treatment, the air is heated to a specific temperature and then is subjected to heat preservation treatment to achieve the heat treatment effect, in the process, the difference between the temperature of the air flow in the kiln body and the specific temperature is too large, so that the heating time of the heating assembly is too long, the treatment period of the plates is long, and the equipment is long in operation time and high in energy consumption.
Disclosure of Invention
Through a great deal of research, after the artificial board is pressed and attached, the formaldehyde content in the artificial board can be effectively reduced and the formaldehyde removal time can be shortened by a multi-stage formaldehyde reduction mode of preheating, heating and keeping constant temperature. And by combining the treatment capacity and the heat energy loss of the plates in the heat treatment process, a continuous formaldehyde-reducing heat treatment kiln is independently designed, and the heat treatment kiln can be used for treating large batches of plates and a circulating heat reflux mode is adopted, so that the effects of short heat treatment period, reduction of thermal loss and improvement of heat efficiency of the plates can be achieved.
Therefore, the first object of the present invention is to provide a formaldehyde-reducing heat treatment process, comprising the following steps:
s1, putting the artificial board into a formaldehyde-reducing heat treatment kiln for heat treatment;
s2, placing the artificial board subjected to heat treatment in the S1 into a curing balance chamber for curing;
in the S1, a preheating-heating-constant-temperature multi-stage aldehyde reduction mode is adopted as a heat treatment mode, the constant temperature is 110-130 ℃, and the constant temperature time is 1-4 h; (ii) a The preheating temperature is 50-80 ℃, and the preheating time is 0.5-6 h.
If the artificial board is subjected to long-time high-temperature treatment, the thermal decomposition of the urea-formaldehyde resin can be caused, and the more serious the thermal decomposition, the internal bonding strength of the urea-formaldehyde resin and the artificial board is reduced, which is not beneficial to the later use of the artificial board. If the artificial board is subjected to long-time low-temperature treatment, the release of formaldehyde is not facilitated, and the plasticization of the adhesive is also not facilitated.
According to the method, a multi-stage formaldehyde reducing mode of preheating, heating and constant temperature is adopted, a part of formaldehyde is released from the preheated board, then the formaldehyde is further released in the heating and constant temperature process, the aim of removing the formaldehyde is achieved by gradually releasing the formaldehyde, and the bonding strength of the adhesive and the artificial board can be well maintained.
The method comprises the following steps:
the artificial board is subjected to multilayer bonding through an adhesive, the adhesive contains urea-formaldehyde resin, the urea-formaldehyde resin cannot be completely cured at high temperature in a short time, the artificial board is subjected to preheating treatment to promote the curing of the urea-formaldehyde resin, so that the bound formaldehyde is firmly locked, a part of free formaldehyde can be released, and then the free formaldehyde is further released in the heating and constant-temperature processes. In addition, the molecule rearrangement-methylene bond rearrangement of the solidified thermoplastic part can be carried out to form a more compact network structure, so that the bonding strength between the artificial boards is enhanced.
In the heating and constant temperature treatment stages, on one hand, along with the rise of the heat treatment temperature, the heat movement of formaldehyde molecules in the heat treatment process is accelerated, and the release of free formaldehyde remained in the artificial board to the outside is promoted; on the other hand, the pore structure characteristics of the artificial board are also changed by the increase of the temperature, so that the adsorption capacity and the adsorption capacity of the artificial board to formaldehyde are reduced, the further release of the formaldehyde in the artificial board is facilitated, and the formaldehyde in the artificial board is fully released in the heat treatment stage. After the urea-formaldehyde resin is subjected to preheating treatment, the urea-formaldehyde resin is partially cured and is not easy to decompose at high temperature, and the urea-formaldehyde resin can be prevented from decomposing at high temperature for a long time so as to release free formaldehyde.
The second purpose of the invention is to provide a continuous energy-saving and aldehyde-reducing heat treatment kiln, which comprises a preheating kiln section, an aldehyde-reducing kiln section and a balance kiln section which are connected in sequence, wherein the preheating kiln section is provided with a feed inlet, and the balance kiln section is provided with a discharge outlet; the aldehyde reduction kiln section is provided with a heat supply assembly, an airflow conveying assembly is arranged between the balance kiln section and the preheating kiln section, and the airflow conveying assembly is used for conveying airflow of the balance kiln section to the preheating kiln section.
In the invention, the preheating process is carried out in the preheating kiln section, and the heating and constant temperature process is carried out in the aldehyde-reducing kiln section.
This application carries out thermal treatment to the artificial board through the mode that adopts continuous type backward flow heat supply, can reduce the heat consumption among the thermal treatment process, carries the air current of balance kiln section to preheating the kiln section through the air current conveying subassembly in, has realized the retrieval and utilization of hot gas flow. Because the kiln section is configured in a sectional mode, continuous batch processing of the aldehyde-reducing heat treatment process of the artificial plates can be realized, so that the processing requirements of large-batch plates can be met, and the production efficiency is improved.
The invention has the beneficial effects that:
(1) by adopting a multi-stage formaldehyde reducing mode of preheating, heating and constant temperature, a part of formaldehyde is released from the preheated board, then formaldehyde is further released in the heating and constant temperature process, the formaldehyde reducing purpose is achieved by gradually releasing formaldehyde, the bonding strength of the adhesive and the artificial board can be well maintained, and the formaldehyde reducing period can be shortened;
(2) the heat consumption in the heat treatment process can be reduced by a continuous reflux heat supply mode, the heat treatment period is shortened, and the continuous batch treatment of the aldehyde-reducing heat treatment process for the artificial plates can be realized by combining the sectional configuration of the kiln section, so that the production efficiency is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
FIG. 1 is a schematic structural diagram of a continuous energy-saving aldehyde-reducing heat treatment kiln in example 8;
FIG. 2 is a schematic view showing the structure of the inner side of a kiln cover in the aldehyde reducing kiln section in example 8;
FIG. 3 is a schematic view showing the structure of the inner wall of the kiln in the aldehyde-reducing kiln section in example 8;
fig. 4 is a sectional view taken along a-a in fig. 1.
Reference numerals: 100- -preheating the kiln section; 110- -a feed inlet; 200-aldehyde reduction kiln section; 211-water spray pipe; 212- -an atomizer head; 221- -exhaust collection tank; 222- -rotating spray tower; 223- -UV photo-oxygen catalysis equipment; 224-centrifugal fan; 225-a muffler; 226- -exhaust gas discharge pipe; 230- -exhaust pipe; 300- -balance kiln section; 310- -discharge hole; 331- -Heat exchange Fan; 332- -gas flow delivery channel; a. an airflow circulation assembly; b. a heat sink; c. a first delivery port; d. and (5) conveying the belt.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
In the description of the present invention, it should be noted that if the terms "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which is usually placed when the product of the present invention is used, the description is merely for convenience of describing the present invention and simplifying the description, but the indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation and operation, and thus, cannot be understood as the limitation of the present invention.
In the description of the present invention, it should be further noted that unless otherwise explicitly stated or limited, the terms "disposed," "configured," "connected," and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; 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.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. 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 invention.
Example 1
An aldehyde-reducing heat treatment process comprises the following steps:
s1, putting the artificial board into a formaldehyde-reducing heat treatment kiln for heat treatment; the heat treatment mode adopts a preheating-heating-constant temperature multi-stage aldehyde reduction mode, wherein the preheating temperature is 70 ℃, the preheating time is 2 hours, the constant temperature is 120 ℃, and the constant temperature time is 2 hours;
s2, placing the artificial board subjected to heat treatment in the S1 into a curing balance chamber for curing; the health preserving time is 5 days;
in this embodiment, the artificial board is a semi-finished board obtained by pressing and pasting an artificial board coated with the formaldehyde removing solution by a roller or a semi-finished board obtained by veneering an artificial board, and in this embodiment, the artificial board coated with the formaldehyde removing solution by a roller is a semi-finished board obtained by pressing and pasting an artificial board.
The water content of the artificial board before heat treatment is 10 percent, and the density of the artificial board is 0.75g/cm3. The health-preserving balance room can realize energy conservation by adopting a solar energy supply mode.
The plate after the aldehyde reduction heat treatment needs to be maintained and balanced for a period of time before further processing so as to recover a certain water content and eliminate the residual stress of the plate, thereby ensuring the product quality. Due to the fact that solar energy is strong in seasonality, a heat pump dehumidifier is additionally arranged in the health preserving balance chamber in non-summer time so as to maintain the temperature and humidity state in the health preserving balance chamber, and further product quality is guaranteed.
In this embodiment, the preheating time is the same as the constant temperature time.
Example 2
The present example is different from example 1 in the temperature, time and curing time of preheating, heating and constant temperature.
In this embodiment, the preheating temperature is 50 ℃, the preheating time is 3 hours, the constant temperature is 110 ℃, the constant temperature time is 4 hours, and the curing time is 3 days.
Example 3
The present example is different from example 1 in the temperature, time and curing time of preheating, heating and constant temperature.
In this embodiment, the preheating temperature is 80 ℃, the preheating time is 2 hours, the constant temperature is 130 ℃, the constant temperature time is 1 hour, and the curing time is 7 days.
Example 4
The difference between this example and example 1 is that the temperature, time and curing time of preheating, heating and constant temperature were different.
In this embodiment, the preheating temperature is 80 ℃, the preheating time is 6 hours, the constant temperature is 110 ℃, the constant temperature time is 3 hours, and the curing time is 7 days.
Example 5
This example differs from example 1 in the water content and density.
In this example, the water content before the heat treatment was 15%, and the density of the artificial board was 0.9g/cm3。
Example 6
This example differs from example 1 in the water content and density.
In this example, the water content before the heat treatment was 12%, and the density of the artificial board was 0.6g/cm3。
Example 7
The difference between this embodiment and embodiment 1 is that the artificial board is different from the artificial board, and the artificial board is a semi-finished board which is roll-coated with an aldehyde removing solution and is subjected to a pressing treatment.
Example 8
As shown in fig. 1 to fig. 3, the present embodiment discloses a continuous energy-saving and aldehyde-reducing heat treatment kiln, which comprises a preheating kiln section 100, an aldehyde-reducing kiln section 200 and a balance kiln section 300, which are connected in sequence, wherein the preheating kiln section 100 is provided with a feed inlet 110, and the balance kiln section 300 is provided with a discharge outlet 310; the aldehyde-reducing kiln section 200 is provided with a heat supply assembly, and an airflow conveying assembly is arranged between the balance kiln section 300 and the preheating kiln section 100 and is used for conveying airflow of the balance kiln section 300 to the preheating kiln section 100.
Through adopting the mode of continuous type backward flow heat supply to carry out thermal treatment to the artificial board, can reduce the heat consumption in the thermal treatment process, the air current of balance kiln section 300 carries partial heat, carries the air current of balance kiln section 300 to preheating in the kiln section 100 through the air current conveyor assembly, has realized the retrieval and utilization of hot gas flow. The hot air flow is recycled to the preheating kiln section 100, the artificial board in the preheating kiln section 100 is preheated, and when the preheated artificial board is conveyed to the formaldehyde-reducing kiln section 200, the temperature difference between the temperature value of the artificial board and the heat treatment set temperature value is reduced, so that the heating time of the heating assembly is shortened, the heat consumption is reduced, and the heat efficiency is improved. In addition, because the kiln section is the sectional type configuration, installed artificial panel in every kiln section, when the process of current kiln section was accomplished, need carry on next process, only need through with the artificial panel of current kiln section shift to next kiln section can, realized artificial panel and fallen aldehyde heat treatment process's continuous type batch processing promptly, therefore can satisfy large batch panel processing demand, improve production efficiency. The artificial board output from the balance kiln stage 300 carries less heat, reducing thermal pollution to the environment.
In this embodiment, the airflow conveying assembly includes a heat exchanging fan 331 and an airflow conveying pipe 332 disposed outside the balance kiln section 300, the heat exchanging fan 331 is connected to one end of the airflow conveying pipe 332, and the other end of the airflow conveying pipe 332 is connected to the preheating kiln section 100. The air flow conveying pipe 332 and the heat exchange fan 331 are mutually matched to convey the hot air flow of the balance kiln section 300 to the preheating kiln section 100.
In this embodiment, as shown in fig. 1 and 3, in order to improve the temperature uniformity of the artificial boards in the kiln section and improve the heat treatment effect of the artificial boards in the aldehyde-reducing kiln section 200, airflow circulation assemblies a are disposed in the preheating kiln section 100, the aldehyde-reducing kiln section 200 and the balance kiln section 300. Specifically, the airflow circulation component a is an air interchanger which is uniformly distributed on two sides of the preheating kiln section 100, the formaldehyde-reducing kiln section 200 and the balance kiln section 300, wherein the two sides refer to two sides of the kiln section along the length direction. The ventilator unit circularly drafts and blows air in each kiln section, so that circular airflow is formed in the kiln sections. The ventilator set comprises a first fan and a second fan, and the second fan is arranged below the first fan. The first fan and the second fan can be used as backups for each other, when one fan fails, airflow circulation in the kiln section is not affected, and when necessary, the two fans can be used simultaneously to enhance air flow.
In this embodiment, as shown in fig. 2, the artificial board is heated in the aldehyde-reducing kiln section 200 to increase the temperature, so that the moisture in the artificial board is excessively lost, the internal quality of the board is affected, and situations such as combustion of the high-temperature artificial board and deformation of the board are avoided, and a spray humidity-conditioning system needs to be configured in the aldehyde-reducing kiln section 200, so as to ensure the humidity of the aldehyde-reducing kiln section 200. The spraying humidity control system comprises water spray pipes 211 and atomizing spray heads 212, the atomizing spray heads 212 are uniformly distributed along the length direction of the water spray pipes 211, the water spray pipes 211 are arranged on the inner surface of a kiln cover of the aldehyde reducing kiln section, the water spray pipes 211 are communicated with a water source, and the water source is provided with a valve.
In this example, an artificial boardDuring the aldehyde-reducing heat treatment process of the wood, particularly under the action of high temperature of which the heat treatment temperature exceeds 120 ℃, the artificial board is affected by extraction components, main wood components, adhesives, additives, technical operations such as veneering and coating treatment and the like in the artificial board, and a certain amount of VOCs are generated. The embodiment can discharge VOCs by arranging the waste gas treatment component at the aldehyde-reducing kiln section 200, thereby improving the quality of the artificial plate. Specifically, as shown in fig. 1, the waste gas treatment assembly comprises a waste gas collection tank 221, a rotary spray tower 222, a UV photo-oxygen catalytic device 223, a centrifugal fan 224, a silencer 225 and a waste gas discharge pipe 226, which are connected in sequence, wherein an exhaust pipe 230 is opened on the aldehyde reduction kiln section 200, and the exhaust pipe 230 is communicated with the waste gas collection tank 221. The spraying medium in the rotary spray tower 222 is a solution containing sodium sulfite and sodium hydroxide and other aldehyde-removing solutions, about 95% of formaldehyde can be removed by spraying the solution, and the residual content of the formaldehyde can reach 1mg/Nm3～4mg/Nm3. A valve is disposed on the exhaust pipe 230. The artificial board releases formaldehyde rapidly in high temperature air, and the exhaust pipe 230 is opened once every 15 minutes in this embodiment to discharge the exhaust gas containing a large amount of formaldehyde in the formaldehyde-reducing kiln section 200 to the exhaust gas treatment component for exhaust gas treatment by opening the valve of the exhaust pipe 230 at intervals.
In this embodiment, the heat supply assembly includes a heat radiator b, the heat radiator b is a bimetal composite fin heat exchanger, and a heat exchange medium of the bimetal composite fin heat exchanger is heat transfer oil or water vapor. The radiator b is arranged above the ventilator unit, and particularly, the radiator b is arranged above the first fan. Each ventilator unit corresponds to a radiator b, the heat medium is conveyed to the radiator b through a conveying pipe, and the radiator b is provided with a valve.
In this embodiment, the continuous energy-saving aldehyde-reducing heat treatment kiln further includes a control assembly, the control assembly includes a temperature sensing instrument, an electromagnetic valve and a control system box, the control system box is disposed outside the aldehyde-reducing kiln section 200, the temperature sensing instrument is installed inside the aldehyde-reducing kiln section 200, the electromagnetic valve is installed in the feeding section of the radiator b, and the temperature sensing instrument and the electromagnetic valve are respectively connected to the control system box. The feed end of the radiator b specifically refers to a feed inlet of a heat exchange medium. The control system box comprises a power control switch and an electromagnetic valve control device, and is used for controlling an electric system of the whole equipment. When the temperature sensing instrument detects that the temperature in the aldehyde reducing kiln section 200 reaches a set temperature value, the temperature sensing instrument transmits a temperature signal to the control system box, the control system box sends a control signal to control the electromagnetic valve to be closed, the aldehyde reducing kiln section 200 stops heating, and a constant temperature state is kept, so that the artificial plate is subjected to heat treatment and aldehyde reduction treatment.
In the embodiment, in order to maintain the temperature difference of each kiln section in the kiln body, the phenomenon of hot air flow crossing is avoided, and the influence on the aldehyde reduction heat treatment effect is avoided. As shown in fig. 4, a first conveying port c through which the artificial board can pass is formed between the preheating kiln section 100 and the aldehyde reducing kiln section 200, a second conveying port through which the artificial board can pass is formed between the aldehyde reducing kiln section 200 and the balance kiln section 300, and conveying belts d for conveying the artificial board are respectively installed on two sides of the first conveying port c and two sides of the second conveying port. After the current treatment process in each kiln section in the kiln body is completed, when the next process is needed, the artificial plates of each kiln section can be conveyed to the next kiln section through the first conveying opening c and the second conveying opening to be treated in the next process. The artificial boards can be conveyed in a mode of automatic stacking by a robot and loading and transferring by a forklift. Besides the mode of automatic stacking by a robot, the mode of arranging a plate conveying channel in the kiln section can be selected for conveying the plates in the kiln section.
In this embodiment, if the temperature of the airflow flowing back from the balance kiln section 300 does not reach the preheating temperature, a heating device may be configured in the preheating kiln section 100, and the heating device performs preheating treatment on the artificial board in the preheating kiln section 100. Other conventional heating assemblies for heating the kiln body or the treatment tank may be selected as heating means by those skilled in the art.
Specifically, the specification of the conventional heat-treated plate is 2440mm × 1220mm × 18mm (length × width × mm), the adjacent two plates are separated by a parting strip, the thickness of the parting strip is 20mm, the size of each small stack is 2500mm × 1300mm × 1500mm × mm 1500mm (length × width × height), the small stacks can be set to be 2 stacks in the height direction, the kiln sections in the heat-treated kiln are respectively a preheating kiln section 100, an aldehyde-reducing kiln section 200 and a balance kiln section 300, each kiln section can be respectively used for placing 16 small stacks of plates (measured by 1500mm height), when the heat treatment time is 3h, the whole body moves forward every 3h, namely, the 3h can heat-treat 16 small stacks of plates, the current theoretical production capacity (loading capacity) is 650 pieces/3 h (single stack, 18mm, 20mm parting strips) or 850 pieces/3 h (double stack, 18mm × 2 mm, 20mm, the plate thickness is not easy to deform, and other high-temperature resistant substances cannot be easily released.
In the embodiment, the continuous energy-saving and aldehyde-reducing heat treatment kiln meets the requirements of sealing, heat preservation and corrosion resistance, the working temperature of the internal design of the kiln body is not less than 120 ℃, the specific detection method is carried out according to the specification in a sawn timber drying equipment performance detection method (GB/T17661-1999), the ① sealing performance needs to meet the requirements that when the temperature of a dry bulb is less than or equal to 100 ℃, 100% of relative humidity can be formed in a room and the relative humidity can be kept for 30-60 min, when the temperature of the dry bulb is more than 100 ℃, the temperature of a wet bulb can be stably measured at 98-100 ℃, and for ② heat preservation performance, the heat preservation performance needs to meet the requirements that when the temperature of a room medium reaches 100 ℃ or above under the condition of no load or load, the temperature difference between the average temperature of the outer surface of the kiln body and the environmental temperature does not exceed 17630 ℃, and for ③ corrosion resistance, the corrosion resistance performance needs to meet the requirements that the corrosion resistance performance of a shell, a framework, a support, a connection, a ventilation, a heating, a diversion, a sealing, a temperature measurement, a control, a carrying and a carrying component used for carrying, a sawing equipment, a drying equipment, and a general drying equipment (GB/dry timber processing technology for carrying, a general drying equipment (L) test method, a general drying equipment (L).
Blank example
A manufactured board without any heat treatment.
Comparative example 1
This comparative example differs from example 1 in that the heat treatment temperature was varied and heating was carried out at 120 ℃ for 4 hours.
Comparative example 2
This comparative example differs from example 1 in that the heat treatment temperature was varied and heating was carried out at 80 ℃ for 4 hours.
Examples of the experiments
Influence of different heat treatment processes on formaldehyde content of artificial board
The experimental method comprises the following steps: the method is carried out by referring to a method for measuring the formaldehyde emission by a dryer method in GBT17657-2013 artificial boards and veneer artificial boards physicochemical property test method.
The specific method is as follows;
(1) 300ml of distilled water was weighed into a crystallization dish, and the dish was placed on the bottom of a 240mm diameter desiccator. And (3) loading the test materials subjected to different heat treatment modes into a metal bracket, wherein the test materials cannot be contacted with each other, and covering and sealing after coating vaseline.
(2) And placing the dryer in an environment with the temperature of 20 +/-2 ℃ for 24 hours to ensure that the distilled water in the crystallizing dish fully absorbs the formaldehyde released by the test piece, wherein the solution is the solution to be detected.
(3) Respectively sucking 25ml of solution to be detected and 25ml of acetylacetone-ammonium acetate solution into a 100ml conical flask, uniformly mixing, placing in a constant-temperature water bath kettle at 65 +/-2 ℃ for heating for 10 minutes to enable formaldehyde to develop color, and then placing the solution in a dark place at 20 ℃ for 60 +/-5 minutes.
(4) And adjusting the wavelength of the spectrophotometer to 412nm, loading the mixed solution to be detected in a cuvette, putting the cuvette into the spectrophotometer, and reading the absorbance value of the mixed solution.
(5) Blank control test: a blank test was conducted in the same manner as in (1), (2), (3) and (4) except that no test piece was placed in the dryer.
The formaldehyde emission amount calculation formula is as follows:
c＝f×(a–b)×1800/A
wherein c is the mass concentration of formaldehyde in mg/L, f is the slope of a standard curve, a is the absorbance of formaldehyde solution, b is the absorbance of blank liquid, A is the surface area of a test piece in cm2。
As can be seen from the calculation formula of the formaldehyde emission, the higher the absorbance, the higher the formaldehyde mass concentration. Therefore, the amount of formaldehyde released can be determined from the amount of absorbance.
The calculation formula of the change rate is as follows:
rate of change ═ B0-B1)/B0*100％
Wherein, B0Absorbance for blank example, B1 is absorbance for comparative example/example.
According to the calculation formula of the change rate, the higher the change rate is, the better the aldehyde reducing effect is.
The results of the experiment are shown in table 1.
TABLE 1 influence of different heat treatment processes on the formaldehyde content of artificial boards
| Sample (I) | Conditions of treatment | Absorbance of the solution | Rate of change |
| Blank example | Untreated | 0.592 | - |
| Comparative example 1 | 120℃4h | 0.421 | 28.9％ |
| Comparative example 2 | 80℃4h | 0.409 | 30.9％ |
| Example 1 | ① preheating at 60 deg.C for 3 hr, ② keeping constant temperature at 120 deg.C for 2 hr | 0.247 | 58.28％ |
| Example 2 | ① preheating at 50 deg.C for 4 hr, ② keeping constant temperature at 110 deg.C for 4 hr | 0.269 | 54.56％ |
| Example 3 | ① preheating at 80 deg.C for 2 hr, ② keeping constant temperature at 130 deg.C for 1 hr | 0.293 | 50.51％ |
The experimental results in table 1 show that the data of the experimental examples are better than those of the blank examples and the comparative examples, and that the artificial board after being preheated, heated and thermostatically treated has the best aldehyde reduction effect on the board, and the best aldehyde reduction effect can reach 58.28%.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The aldehyde-reducing heat treatment process is characterized by comprising the following steps of:
s1, putting the artificial board into a formaldehyde-reducing heat treatment kiln for heat treatment;
s2, placing the artificial board subjected to heat treatment in the S1 into a curing balance chamber for curing;
in the S1, a preheating-heating-constant-temperature multi-stage aldehyde reduction mode is adopted as a heat treatment mode, the constant temperature is 110-130 ℃, and the constant temperature time is 1-4 h; the preheating temperature is 50-80 ℃, and the preheating time is 0.5-6 h.
2. The aldehyde-reducing heat treatment process according to claim 1, wherein the moisture content of the artificial board before heat treatment is 10-15%; the density of the artificial board is 0.6g/cm3～0.9g/cm3。
3. The aldehyde-reducing heat treatment process according to claim 1, wherein the curing time in the S2 is 3 to 7 days.
4. A continuous energy-saving and aldehyde-reducing heat treatment kiln is characterized by comprising a preheating kiln section, an aldehyde-reducing kiln section and a balance kiln section which are sequentially connected, wherein the preheating kiln section is provided with a feed inlet, and the balance kiln section is provided with a discharge outlet;
the aldehyde reduction kiln section is provided with a heat supply assembly, an airflow conveying assembly is arranged between the balance kiln section and the preheating kiln section, and the airflow conveying assembly is used for conveying airflow of the balance kiln section to the preheating kiln section.
5. The continuous energy-saving and aldehyde-reducing heat treatment kiln according to claim 4, wherein the gas flow conveying assembly comprises a heat exchange fan and a gas flow conveying pipeline which are arranged outside the balance kiln section, the heat exchange fan is connected with one end of the gas flow conveying pipeline, and the other end of the gas flow conveying pipeline is connected with the preheating kiln section.
6. The continuous energy saving aldehyde reducing heat treatment kiln according to claim 4 or 5, wherein the preheating kiln section, the aldehyde reducing kiln section and the balancing kiln section are each configured with a gas flow circulation assembly.
7. The continuous energy-saving aldehyde-reducing heat treatment kiln according to claim 4, wherein the aldehyde-reducing kiln section is provided with a spray humidity control system, the spray humidity control system comprises spray pipes and spray nozzles, the spray nozzles are uniformly distributed along the length direction of the spray pipes, the spray pipes are arranged on the inner surface of a kiln cover of the aldehyde-reducing kiln section, the spray pipes are communicated with a water source, and the water source is provided with a valve.
8. The continuous energy-saving formaldehyde-reducing heat treatment kiln according to claim 4 or 5, characterized in that the waste gas treatment component comprises a waste gas collection box, a rotary spray tower, a UV photo-oxygen catalysis device, a centrifugal fan, a silencer and a waste gas discharge pipe which are connected in sequence, wherein the formaldehyde-reducing kiln section is provided with a gas discharge pipe, and the gas discharge pipe is communicated with the waste gas collection box.
9. The continuous energy-saving and aldehyde-reducing heat treatment kiln as claimed in claim 4, wherein the heat supply assembly comprises a heat radiator, the heat radiator is a bimetal composite fin heat exchanger, and the heat exchange medium of the bimetal composite fin heat exchanger is heat conduction oil or water vapor.
10. The continuous energy-saving aldehyde-reducing heat treatment kiln according to claim 9, further comprising a control assembly, wherein the control assembly comprises a temperature sensing instrument, a solenoid valve and a control system box, the control system box is arranged outside the aldehyde-reducing kiln section, the temperature sensing instrument is mounted inside the aldehyde-reducing kiln section, the solenoid valve is mounted in the feeding section of the radiator, and the temperature sensing instrument and the solenoid valve are respectively connected with the control system box.
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