RU2206840C2 - Method of chamber drying of moisture containing materials - Google Patents

Abstract

FIELD: sawing and wood working industry branches, namely chamber drying of moisture containing materials. SUBSTANCE: method comprises steps of blowing drying agent (moistened air) through radiator and stacked sawn material at forming closed circulation loop; taking part of drying agent by means of compressor and pumping it to radiator for creating desired pressure in it. As pressure in radiator exceeds saturation value, vapor condenses and energy separated at such process heats radiator. Circulating through radiator drying agent lowers its temperature causing condensation of vapor in radiator. Mixture of dried air and water discharged from radiator is fed to separator for separating it by air returned to chamber and water discharged outside. EFFECT: enhanced effectiveness of drying process. 2 dwg

Description

 The invention relates to the field of chamber drying of moisture-containing materials and can be used in sawmill, woodworking industry or other areas where chamber drying of materials is carried out.

 A known method of a chamber bag of moisture-containing materials, including condensation of moisture vaporized from a material in a chamber by reducing the humidity of the drying agent and returning the energy received to heat the drying agent (1, 2). Chamber drying of lumber is carried out mainly with the help of steam-air drying chambers. The drying technology provides for stepwise toughening of the drying agent (increasing the temperature and decreasing the humidity of the air washing the pile of lumber) while reducing the humidity of the wood. In this case, it is necessary to stabilize the parameters of the drying agent (moist air) - temperature and humidity. To heat the drying agent, a calorifer equipment is installed in the chamber, which changes the thermal power depending on the required and actual temperature of the drying agent. The humidity of the drying agent is regulated by replacing the moist air in the chamber with drier air coming from the street or utility room (workshop). Exhausted moist air is discharged into the street. As you know, about 2500 kJ / kg (latent heat of vaporization) of energy is spent on moisture evaporation. This energy is lost with the release of air into the atmosphere. To reduce energy losses, recuperators are installed on large-volume chambers, in which the air discharged from the chamber is cooled and the incoming air is heated. However, the efficiency of such systems cannot be high. In winter, almost dry street air, having a low heat capacity, cannot utilize the completely "waste energy" of moist air. In the summer, the recuperator becomes almost useless, because it does not condense moisture from the exhaust air.

 The aim of the invention is the return to the drying chamber of the energy spent on the evaporation of moisture from wood.

 The solution to this problem is provided by the fact that in the method of chamber drying of moisture-containing materials, including condensation of moisture evaporated from the material in the chamber by reducing the humidity of the drying agent and returning the energy received to heat the drying agent, the moistened drying agent is partially selected and sent to the compressor, increasing its pressure and temperature, then it is fed to the heat exchanger under pressure and the temperature of this part of the drying agent is reduced by heating an external moistened drying agent washing the heat a heat exchanger, providing moisture condensation from the drying agent in the heat exchanger, after which the dried agent is sent for drying.

 The technical essence of the invention lies in the fact that moist air is not emitted into the atmosphere, but is absorbed by the compressor, compressed, heated, and enters the air heater installed in the drying space of the chamber. Moisture condensation occurs in the heater blown by the drying agent, and the thermal energy released in this case is transferred to the drying agent, increasing its temperature. Due to the fact that the compressor and heater can be located in the chamber itself, the efficiency of the recovery process reaches values close to 100%.

 The claimed method can be implemented as follows. As mentioned above, the drying of lumber is carried out in a vapor-air environment. To intensify the process, moist air, called a drying agent, is blown through a stack of lumber using fans. An exemplary layout of the chamber with horizontal circulation of the drying agent is shown in figure 1. The scheme of air drainage is shown in figure 2. The stack of lumber 1 is located behind the partition 2, which contributes to the formation of an air flow circulating through the stack of lumber 1. Using a fan 3, a horizontal closed ring of circulating air is formed (shown in Fig. 1 by arrows). After passing through the fan 3, the drying agent passes through the air heater 4, where it cools the moist air under pressure and heats up. Then, additional heating of the agent may occur if the compressor 5 is in the circulation zone. The heated drying agent enters the stack of lumber 1, where it evaporates moisture from the wood and is thereby cooled. The cooled air is drawn in by fan 3 and the cycle continues. To dehumidify the air and restore the required temperature, the compressor 5 takes part of the drying agent circulating in the chamber and directs it under pressure to the inlet of the air heater 4. As a result of blowing the air heater 4 with a circulating agent, the temperature at the outlet of it decreases. As a result of the fact that the pressure at the outlet of the air heater 4 becomes higher than saturation at a given temperature, most of the moisture contained in the agent condenses, returning the energy expended on evaporation to the drying agent. Coming out of the heater 4, the mixture consists of almost dry air and water. This mixture enters the separator 6, where it is separated into air returned to the chamber and water discharged to the outside. The pressure in the heater 4 is regulated by valve 7 and is controlled by a pressure gauge 8.

 Thus, the invention due to energy recovery can significantly reduce energy costs for drying various materials. The energy consumption in this case will be the cost of the initial heating of the material and energy loss through the enclosures of the chamber.

Sources of information
1. G. S. Shubin "Drying and heat treatment of wood", M., "Forest industry", 1990, 336 S.

 2. P.S. Sergovsky, A.I. Rasev "Hydrothermal processing and conservation of wood", M., "Forest industry", 1987, 360 S.

Claims (1)

 The method of chamber drying of moisture-containing materials, including condensation of moisture evaporated from the material by reducing the humidity of the drying agent, and returning the energy obtained to heat the drying agent, characterized in that the condensation of moisture evaporated from the sawn timber is carried out by partial selection of the compressor of the wet drying agent from the chamber and feeding it into air heater with an increase in the latter pressure above the saturation pressure and heating of the air heater as a result of condensation.

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