KR100928196B1 - Control method for complex dehydration system - Google Patents

Abstract

PURPOSE: A control method of a complex desiccant cold air drying system is provided to keep temperature and humidity of a drying room by dewetting and pre-heating wet air of a drying room by selectively operating a cold air drying unit and a desiccant drying unit. CONSTITUTION: A control method of a complex desiccant cold air drying system is composed of a drying room(R) receiving an object, a cold air drying unit(C), and a desiccant drying unit(D). The cold air drying unit is composed of a refrigerant compressor(101), an outdoor unit(106), an expansion valve(112), an evaporator(114), and a pre-heating condenser(110). The expansion valve expands the refrigerant which passes the outdoor unit. The evaporator cools and dehumidifies the air by heat-exchanging the wet air of the drying room and the refrigerant which passes the expansion valve. The pre-heating condenser preheats the air dehumidified in the evaporator. The desiccant drying unit dehumidifies and pre-heats the air of the drying room. The desiccant drying unit is composed of a rotor(304) and a regenerating heater(305) and heats the regenerating air at the high temperature.

Description

Control Method for Complex Dehydration System

The present invention relates to a control method of a combined cold air drying system, and more particularly, by providing a cold air drying unit and a desiccant drying unit, and selectively or separately (co-parallel) operation according to the humidity of the drying chamber. The present invention relates to a control method of a combined cold air drying system that can increase drying efficiency and reduce operating costs by shortening drying time.

In general, in the field of drying, there are hot air drying, cold air drying, and freeze vacuum drying, and the drying method is selected by economics and experience depending on the dry matter.

Among them, cold air drying is delayed in the development of technology despite the good taste, aroma, quality, and functionality of food.

The drying process of the dry matter is the initial dry rate drying and the dry rate reduction drying at the end, and in the constant temperature drying zone, in the constant temperature drying zone, the cooling calories are used to remove latent heat load and are used to evaporate moisture of the dry matter. The heating load uses the condenser array load, and the cooling coil inlet and outlet has a large difference in efficiency, but after a certain period of time, the sensation drying zone has a larger sensible cooling load than the heat of cooling and a smaller absolute humidity difference to dehumidify. Energy use is not efficient.

The rate drying is almost the same as the evaporation of water from the water surface. That is, the drying speed is constant as the initial drying.

The rate reduction drying is reduced by changing the drying rate and the water evaporation amount * water content linearly (proportionally) after the constant drying. This is referred to as 1 step dry rate reduction.

Next, the drying rate, moisture content, and water evaporation curve change. This is called desensitization drying two-stage.

Combination cold air drying system includes mosquito flavor, powder seasoning, refined medicine, instant food, sugar processed food, confectionery drying, fiber and electronic parts, leather, agricultural products, seeds, seafood, Haitai, fish and shellfish processed food, synthetic resin, tobacco, It is widely applied to sludge, etc., and can be introduced into new fields even in high temperature fields such as hot air drying.

As a prior patent, Korean Patent No. 10-0614280 discloses a low dew point cooling dehumidification system and a cooling dehumidification method.

Looking at the contents of the prior patent, relates to a low dew point cooling and dehumidifying apparatus including a compressor, a condenser, an expansion valve, an evaporator and a blower to allow air to pass through the evaporator,

A liquid pipe valve installed during the cooling cycle; A comparison sensor installed before and after the evaporator; A reheat coil connected in parallel with the condenser and through which air from the evaporator passes; A hot gas valve installed at an inlet side of the reheat coil; A condenser valve installed at the condenser inlet side; A low pressure switch installed between the compressor and the evaporator; An evaporator temperature sensor connected to the evaporator is included so that air passing through the evaporator passes through the reheat coil.

However, the prior art has some problems.

In other words, cold dew point drying is hard to operate under dew point temperature below 5 ℃, and even low temperature in cold wind drying maintains low humidity in cold wind drying. The dehumidification efficiency of the refrigerator relative to the load is reduced, there is a problem that the operating cost is increased.

In addition, cold air drying is advantageous in the drying process by utilizing the condenser arrangement 100% for the constant drying, but during the desensitizing drying, the drying of the dried material is slowed down and the dehumidification amount is considerably lower than the cooling capacity. There is a problem that the operating cost increases as the drying time of the late.

The present invention has been made to solve the above problems of the prior art, the drying efficiency and drying time by a single (separate) operation or simultaneous (parallel) operation of the cold air drying unit and the desiccant drying unit when the humidity of the drying chamber is high. When the humidity of the drying room is low, the cold air (temperature control) drying unit performs cold wind operation and the desiccant drying unit performs dehumidification (humidity control) operation to improve the dehumidification (drying) performance, thereby reducing drying time and energy. The purpose of the present invention is to provide a control method for a combined cold air drying system that can be drastically reduced and can be applied to the freeze vacuum drying field, which is gradually expensive.

The object of the present invention described above,

A drying chamber in which dry items are stored;

A compressor for compressing a refrigerant, an outdoor unit for condensing and air-cooling the compressed refrigerant, an expansion valve for expanding the refrigerant having passed through the outdoor unit, an evaporator for cooling and dehumidifying by exchanging the refrigerant passing through the expansion valve with wet ventilation recovered from a drying chamber, and the compressor Cooling air drying unit consisting of a reheat condenser for preheating the ventilation dehumidified in the evaporator using an arrangement generated by receiving the condensed refrigerant compressed in the;

It includes a desiccant drying unit consisting of a desiccant rotor for heating and dehumidifying the ventilation recovered from the drying chamber, a heater for supplying a heating heat source to the desiccant rotor,

The cold air drying unit and the desiccant drying unit is operated according to a specific condition to dehumidify and heat the humid air in the drying chamber to circulate to the drying chamber to control the combined cold air drying system to maintain the temperature and humidity in the drying chamber at the target value Is achieved by

According to the present invention, desiccant drying, which achieves the maximum effect in cold air drying (dehumidification) and desensitization drying, which is effective in the constant drying of a dry matter through separate (separate) operation and simultaneous (parallel) operation of the cold air drying unit and the desiccant drying unit. The combination of the (dehumidifier) reduces the drying time of the dried products by up to 63% or more, which has the effect of reducing operating costs and improving productivity in the user.

 Example) 100kg dry dried nogari (based on ecological 95.2kg + wash 4.8kg)

   Reduced weight 74% Dry weight 28.6kg Fully dry

   (80.3% ecological water content, 11.3% dry water content 69%)

   Cold Air Dryer 1HP (Required Input 1kw) Air Flow 480kg / h, Circulation Fan 0.75kw in Drying Room

   Desiccant dry regeneration heater 2.7kw + fan 0.3kw

 In addition, the conventional cold air drying is easy to store at a constant low temperature after drying the dry matter, the present invention can control the humidity, including the temperature, there is an effect that is easy to long-term storage without damage to the dry matter.

In addition, the present invention does not produce condensation water because the cooling coil dew point temperature is lower than the cooling coil dew point temperature when the constant humidity is lowered by desiccant drying in a wet coil or a desensitization drying zone where condensation water is generated in the cooling coil of cold air drying during constant drying. Coiled and prevents bacterial and mold growth in wet cooling coils, so it has an ideal effect on hygiene and food safety.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 3 is a view showing a combined cold air drying system according to the present invention.

In the accompanying drawings, the solid line means that the movement of the actual fluid is performed, and the dashed line represents only the flow path, although the movement of the fluid is not performed.

In addition, in the accompanying drawings, R.A means ventilation, S.A means air supply, and E.A means exhaust.

As shown in Figures 1 to 3, the combined cold air drying system according to the present invention, the drying chamber (R) having a space for loading the object to be dried; Cold air drying unit (C); Desiccant drying unit (D); It includes a control unit 100.

The cold air drying unit (C) is a compressor (101) for compressing the refrigerant, an outdoor unit (106) for condensing and air-cooling the compressed refrigerant, an expansion valve (112) for expanding the refrigerant passing through the outdoor unit (106), and the expansion valve ( The refrigerant passing through 112 and the evaporator 114 for cooling and dehumidifying by heat-exchanging the humid ventilation recovered from the drying chamber R and the refrigerant compressed by the compressor 101 are condensed by using the generated evaporator ( A reheat condenser 110 for preheating the ventilation dehumidified at 114, an air supply fan 201 for sucking cooling air from the evaporator 114, and an air supply line connected to the air supply fan 201 and communicating with the drying chamber R. 200, a ventilation line 300 connected to the drying chamber R and connected to the evaporator 114.

The desiccant drying unit D may include a ventilation line 300a connected to a drying chamber R, an air filter 301 connected to the ventilation line 300a, and a ventilation line 300a passing through the air filter 301. Connected to the desiccant rotor 304, the heater 305 connected to the desiccant rotor 304 and supplying heating air, and the dehumidified and dried air passing through the desiccant rotor 304 to suck in the air supply line 200a. Air supply fan 201a to be supplied to the supply, the air supply fan (201a) and the air supply line (200a) connected to the drying chamber (R).

In addition, an exhaust fan 307 is further provided to discharge the heat lost through the desiccant rotor 304 to the outside.

The control unit 100 includes a conventional microprocessor and a memory, and controls the cold air drying unit C and the desiccant drying unit D to be selectively operated according to specific conditions. This will be described later.

On the other hand, the desiccant rotor 304 is divided into an adsorption (dehumidification) section, a purge (precooling, preheating) section and a desorption (regeneration) section.

The area of each region is changeable, an example of which is schematically shown in the upper right of FIG.

As shown in the upper right side of Fig. 1, the area ratio of the adsorption (dehumidification) area: purge area: desorption (regeneration) area is set to 4: 1: 1 or 2: 1: 1.

The adsorption (dehumidification) part region (the part indicated by "4" or "2" in the lower part) is a part which adsorbs and dehumidifies the moisture contained in ventilation.

The desorption (regeneration) portion region (the portion indicated by "1" on the upper left side) is a portion which receives the heated air from the heater 305 and evaporates and adsorbs the adsorbed moisture.

The purge section (part labeled "1" in the upper right) recovers the heat heated to the highest temperature in the desorption (regeneration) section and supplies it back to the heater 305 to pass through the adsorption (dehumidification) section. The temperature of the regenerated air can be further lowered, at which time the taken heat can be reused as a heat source of the heater 305.

Hereinafter, a control method of operating the combined cold air drying system according to the set mode according to the present invention will be described.

The control method of the combined desiccant cold air drying system of the present invention is a method in which the microprocessor operates only the cold air drying unit (C) according to the humidity and temperature load of the drying chamber (R) according to the condition stored in the memory of the control unit (100) It is controlled by the method of operating only the kant drying part D, and the method of operating the cold air drying part C and the desiccant drying part D in parallel.

As shown in Figure 1, the constant drying according to the first embodiment of the control method of the combined desiccant cold air drying system according to the present invention, the drying chamber (R) having a space for loading the dried object; Cold air drying unit (C); Desiccant drying unit (D); In the method for controlling a combined cold air drying system including a control unit 100, the cold air drying unit (C) is operated, the operation of the desiccant drying unit (D) is stopped.

More specifically, the cold air drying unit C is operated to maintain the target humidity of the drying chamber R at 40% or less.

That is, a process of cooling and dehumidifying the humid ventilation recovered in the drying chamber R by heat exchange in the evaporator 114, and discharging the condensed water generated in the evaporator 114 to the outside through a drain pipe.

B process of reheating the air dehumidified in the step a to heat exchange in the reheat condenser 110 to have a heat amount necessary for drying the dried object,

It consists of a step c which supplies the air reheated in the step b into the drying chamber (R) through the air supply fan 201 to perform the constant drying.

On the other hand, as shown in Figure 2, the constant drying according to the second embodiment of the control method of the combined desiccant cold air drying system according to the present invention, the drying chamber (R) having a space for loading the dried object; Cold air drying unit (C); Desiccant drying unit (D); In the method for controlling a combined cold air drying system including a control unit 100, the cold air drying unit (C) is stopped and only the desiccant drying unit (D) is operated.

That is, when the outside air temperature is lower than the drying chamber (R) and the humidity in the drying chamber (R) is high in winter, the desiccant drying unit (D) is operated to heat and dehumidify the humid air in the drying chamber (R) and supply it to the drying chamber (R). It is.

The operation of the desiccant drying unit D is preheated by heat exchange of the desiccant rotor 304 while adsorbing and dehumidifying the wet ventilation in the drying chamber R while passing through the adsorption (dehumidification) region of the desiccant rotor 304. Some air during the ventilation is passed to the purge part of the desiccant rotor 304 to heat the preheated regenerated air in the heater 305 to a high temperature, and then the desiccant rotor (at the desorption (regeneration) portion of the desiccant rotor 304). The high temperature and high humidity regenerated air obtained by desorbing (regenerating) the water of 304 is discharged to the outside through the regenerated exhaust fan.

At this time, the outside air inlet damper attached to the cold air drying unit (C) is opened in conjunction with the regenerated exhaust amount to be regenerated to automatically open air by the air pressure difference in the drying chamber (R) to help drying in the drying chamber.

As shown in Figure 3, the cold air drying according to the third embodiment of the control method of the combined desiccant cold air drying system according to the present invention, the drying chamber (R) having a space for loading the dried object; Cold air drying unit (C); Desiccant drying unit (D); In the method for controlling the combined cold air drying system including the control unit 100, the cold air drying unit (C) and the desiccant drying unit (D) to operate in parallel to dehumidify rapidly. This shortens the drying time, thereby reducing the operating costs and increasing the yield.

That is, a process of cooling and dehumidifying the humid ventilation recovered in the drying chamber R by exchanging heat to the evaporator 114 and discharging condensed water generated in the evaporator 114 to the outside through a drain pipe,

B process of reheating the air dehumidified in the step a to heat exchange in the reheat condenser 110 to have a heat amount necessary for drying the dried object,

Operation of the cold air drying unit including a step c to supply the air reheated in the step b into the drying chamber (R) through the air supply fan 201 is performed.

At the same time, wet ventilation in the drying chamber R is supplied to the adsorption (rehumidification) region of the desiccant rotor 304 for adsorption and dehumidification, and the desorption (regeneration) region of the desiccant rotor 304 is provided by the heater 305. Operation of the desiccant drying unit D for supplying preheated air to the drying chamber R after heating the wet ventilation by the heating heat source supplied to the drying chamber R is performed in parallel.

Here, some of the ventilation is preheated by heat exchange passing through the purge portion of the desiccant rotor 304 as regeneration air.

The preheated regenerated air is heated to about 140 ° C. in the heater 305 and then supplied to the desorption (regeneration) portion of the desiccant rotor 304, and the high temperature and high humidity is desorbed (regenerated) by the high temperature regeneration air. Of the regenerated air is discharged to the outside by the exhaust fan (307).

In addition, when the desiccant drying unit (D) operates, the system is configured to always open in conjunction with an external air inlet damper (not shown) of the cold air drying unit (C).

Meanwhile, in the third embodiment, when the external temperature is lower than the drying chamber and the humidity of the drying chamber is high, only the desiccant drying unit is operated to maintain the drying chamber R at a target humidity.

On the other hand, in the third embodiment, when the external temperature is 5 ~ 10 ℃, the humidity is 20% or less to operate the cold air drying unit (C) and the desiccant drying unit (D) in parallel to operate in a low temperature and low humidity state do.

The drying experiment to which the present invention configured as described above is applied will be described.

As an example of the dry matter, the actual operation of Nogari in cold wind drying has an ecological water content of 80.3% and a dry water content of 11.3%, with a 74% weight loss over 4 days. Moisture increased by% and weight loss by 74%.

50% on Day 1, 14% on Day 2, 7% on Day 3, and 3% on Day 4. The indoor drying conditions are 25 ~ 26 ℃ DB, 25 ~ 30% RH.

Based on this data, the dehumidification condition is calculated as 1st day with constant dry and 50/3 = 16.67kg, 2nd day 14/3 = 4.67kg, 3rd day 7/3 = 2.33kg, 4th day and 1kg The difference between dehumidification at the beginning and the end is 16.67 times.

If the room conditions are 25 ℃ and 30%, the absolute humidity is 5.89g / kg '25 ℃, 80% and 15.96g / kg'. Therefore, when operating under the same conditions, △ x = 15.96-5.89 = 10.07g / kg ' .

Therefore, Day 4 absolute humidity difference is △ x = 10.07 / 16.67 = 0.6g / kg ', Day 3 △ x = 0.6 * 2.33 = 1.4g / kg', Day 2 △ x = 0.6 * 4.67 = 2.8g / kg ' On day 1, Δx = 0.6 * 16.76 = 10.06g / kg '.

On the first day, it is driven by drag dry, and from day 2, it is driven by dry rate dry.

This is dried in a parallel manner of the present invention combined cold air drying system cold wind drying unit and desiccant drying unit, and compared with the conventional cold air drying system through the following [Table 1], [Table 2], [Table 3] Able to know.

TABLE 1

Conventional cold air drying system

TABLE 2

Combined cold air drying system

TABLE 3

Examination of drying time in separate operation and simultaneous operation in combined cold air drying system

[Table 3] summarizes the absolute humidity according to the relative humidity in the drying room during cold air drying. 4.49 ~ 2.39g / kg 'up to 80% ~ 50% of the constant drying zone, and 43% ~ 30% of the reduced drying zone. 1.62 ~ 0.15 g / kg 'and drying time, it took 24hr to reduce from 80% to 43% and 72hr to lower from 43% to 30%, so the dehumidification amount was significantly lower than the input heat in the low relative humidity. It can be seen that.

It is possible to complete the drying within 24hr through cold wind drying in the constant drying zone, desiccant purge drying in the rate drying zone, cold air drying on the first day, and cooling and desiccant purge drying on the second day.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it will be readily apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention, all such modifications and modifications being attached It is obvious that the claims belong to the claims.

1 to 3 is a view showing a combined cold air drying system according to the present invention.

Explanation of symbols on the main parts of the drawings

100: refrigerant line 101: compressor

106: outdoor unit 112: expansion valve

114: evaporator 200: freeze drying air line

201: supply fan 300: air line

304: desiccant rotor 305: heater

Claims (7)

A drying chamber in which dry items are stored; A compressor for compressing a refrigerant, an outdoor unit for condensing and air-cooling the compressed refrigerant, an expansion valve for expanding the refrigerant having passed through the outdoor unit, an evaporator for cooling and dehumidifying by exchanging the refrigerant passing through the expansion valve with wet ventilation recovered from a drying chamber, and the compressor A reheat condenser for preheating the dehumidified cooling in the evaporator, an air supply fan for sucking cooling air of the evaporator, and an air supply line connected to the air supply fan and connected to a drying chamber by using a condensed refrigerant supplied from the condenser. A cold air drying unit configured to be connected to the drying chamber and to have a ventilation line connected to the evaporator; A desiccant rotor for heating and dehumidifying the ventilation recovered in the drying chamber, a method for controlling a combined cold air drying system comprising a desiccant drying unit and a control unit comprising a heater for supplying a heating heat source to the desiccant rotor, The control unit is configured to operate the cold air drying unit and the desiccant drying unit according to a specific condition to dehumidify and heat the humid air in the drying chamber to circulate to the drying chamber to maintain the temperature and humidity in the drying chamber at a target value Control method of drying system. The method of claim 1, The control unit performs the constant drying by operating only the cold air drying unit to maintain the target humidity of the drying chamber to 40% or less, The rate drying is A process of exchanging the humidified air recovered in the drying chamber by exchanging heat to the evaporator to cool and dehumidify and discharge the condensed water generated in the evaporator to the outside through a drain pipe; B-heating the dehumidified air in the step a to heat-exchange in a reheat condenser to have a heat amount necessary for drying the dried object; C step of supplying the air reheated in the step b into the drying chamber through an air supply fan; Control method of a combined cold air drying system, characterized in that it comprises a. The method of claim 1, If the outside temperature is lower than the drying room and the humidity is high in the drying room, The control unit operates the desiccant drying unit to supply the humid ventilation in the drying chamber to the desiccant rotor to adsorb and dehumidify, The method of controlling a combined cold air drying system, characterized in that the wet ventilation is heated by the heating heat source supplied from the heater to the desiccant rotor, dried and supplied to the drying chamber. The method of claim 1, If the outside temperature is lower than the drying chamber, the humidity of the drying chamber, the control unit controls the combined cold air drying system, characterized in that to operate only the desiccant drying unit to maintain the drying chamber to the target humidity. The method of claim 1, When the external temperature is 5 ~ 10 ℃, the humidity is 20% or less, the control unit operates the cold air drying unit and the desiccant drying unit in parallel to operate in a low temperature and low humidity state control method of a combined cold air drying system. The method of claim 1, The controller controls the cold air drying unit and the desiccant drying unit in parallel to rapidly dehumidify the drying chamber. Operation of the cold air drying unit, A process of cooling and dehumidifying the humidified air recovered in the drying chamber by exchanging heat to the evaporator and discharging condensed water generated in the evaporator to the outside through a drain pipe; B process of heating the dehumidified air in the step a to heat exchange in a reheat condenser to have a heat quantity necessary for drying the dried object, A step c for supplying the air heated in the step b into the drying chamber through an air supply fan, Operation of the desiccant drying unit, Adsorption dehumidification by supplying the humid ventilation in the drying chamber to the desiccant rotor, The method of controlling a combined cold air drying system, characterized in that the wet ventilation is heated by the heating heat source supplied from the heater to the desiccant rotor, dried and supplied to the drying chamber. The method of claim 1, When the desiccant drying unit is operated, the controller A control method for a combined cold air drying system, characterized in that the external air is automatically introduced by operating the air intake damper of the cold air dryer to assist the exhaust of the regenerated air.

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