KR100853910B1 - Sludge vacuum drying apparatus and the method - Google Patents

Abstract

An apparatus for sludge vacuum drying is provided to lower the driving cost of the apparatus by efficiently utilizing energy generated while driving a heat exchanger, and a method for sludge vacuum drying using the apparatus is provided. In a sludge vacuum drying apparatus for passing sludge injected from an injection tank(1) through a drum(3) to heat the sludge at a pressure of an atmospheric pressure or less, dewatering the heated sludge, and moving the dewatered sludge to a discharge tank(5), the sludge vacuum drying apparatus comprises: a transfer unit(T) including a rotary shaft(10) rotated by power of a motor(7) and a transfer screw(12) rotated together with the rotary shaft to transfer sludge; a heating unit(20) for transferring heat into the drum to heat sludge in the drum; a cold trap part(30) including an evaporator(32) for liquefying the water vapor by cooling the water vapor with heat of vaporization of a circulating refrigerant when water vapor is produced in the drum by heating sludge and flown in through an induction pipe(25); a compressor(40) for compressing a refrigerant in a vapor state passing through the evaporator into gas with a high temperature and a high pressure; and a vacuum pump(9) for decompressing an internal space of the drum to a pressure of an atmospheric pressure or less, wherein a refrigerant pipe(1) through which a fluid can flow is formed on the transfer unit, and refrigerant gas with a high temperature compressed by the compressor is supplied to one end of the refrigerant pipe, cooled through a heat exchange with surrounding sludge, discharged to the other end of the refrigerant pipe, and then flown into the evaporator again via an expansion valve(50).

Description

Sludge Vacuum Drying Apparatus and the Method

1 is a block diagram of a sludge vacuum drying apparatus according to an embodiment of the present invention,

Figure 2a is a block diagram of an evaporator according to an embodiment of the present invention,

Figure 2b is an exploded perspective view of the spiral tube of the evaporator according to an embodiment of the present invention,

2C is a cross-sectional view of an evaporator in accordance with one embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

1: input tank 3: drum

5: discharge tank 7: motor

9: vacuum pump 10: rotating shaft

11: refrigerant piping 12: transfer screw

20: heating means 25: induction pipe

30: cold trap unit 32: evaporator

40 compressor 50 expansion valve

In general, sludge generated in sewage treatment plants, water treatment plants, food waste treatment plants, and wastewater treatment plants generally has a water content of 80 to 90%. When the sludge with high moisture content is landfilled without dehydration, the leachate flowing out of the sludge gradually degrades the surrounding soil and rivers and destroys the ecosystem. As there is a problem of being lost, laws of various countries including Korea are gradually being revised to ban landfilling of organic sludge including water. Therefore, in Korea, sludge generated at millions of tons per year should be replaced by incineration, melting, coagulation, and composting.However, in order to apply such alternative treatment technology, high efficiency can be used to reduce the amount of water contained in the sludge. A sludge drying (dewatering) device should be installed.

The sludge dewatering apparatus used in the conventional industrial field includes a centrifugal dehydrator, a pressurized dehydrator and a vacuum dehydrator.

While the centrifugal force dehydrator has a high dehydration rate, wear of the centrifugal drum is severe and cake processing is not smooth, and thus, continuous operation is limited and thus it is not widely applied to the field. The pressurized dehydrator is advantageous for high capacity treatment, but has a low dehydration rate and a complicated cake treatment.

In addition, the vacuum dehydrator (using the dehydration principle due to the mechanical force generated by the pressure difference) is a vacuum principle, the coarse sludge is adsorbed to the filter cloth using a vacuum pump, while maintaining the atmospheric pressure on the adsorption side On the opposite side, it is a dehydrator which generates a vacuum and removes water by the pressure difference between both sides.

The sludge vacuum drying apparatus according to the present invention uses a drying principle similar to Utility Model Application No. 20-1999-0021450, rather than the vacuum dehydration method by the suction force generated by the pressure difference between the vacuum pressure and the atmospheric pressure.

That is, by lowering the pressure of the space where the sludge is dried below atmospheric pressure, the boiling point of water (H ₂ O) is lowered (for example, the boiling point of water at 65 kPa is 65 ° C.), and the water contained in the sludge is more than 100 ° C. (0.10135). Evaporation at a temperature lower than the boiling point at Mpa). This principle of operation makes it possible to reduce the amount of heating for evaporation, which is a highly efficient drying technique.

Utility Model Application No. 20-1999-0021450 is a "storage tank in which collected high concentration livestock wastewater and sludge are stored, and having a transfer pump for supplying the stored wastewater and sludge to a vacuum dry dehydrator; and the wastewater supplied from the storage tank and The stirring means for agitating the sludge is installed on the rotating shaft rotated by the drive motor, and the sludge discharge valve for discharging the dried sludge is installed, and the heating plate is installed to increase the drying efficiency by applying heat to the waste water and the sludge. A vacuum drying dehydrator and a vacuum drying dehydrator to condense water vapor generated in the vacuum drying dehydrator and to reduce the boiling point temperature of the waste water to reduce the boiling point temperature of the waste water and to generate a temperature difference with the heat transfer surface to increase the amount of heat exchange It provides a sludge vacuum drying dehydration device composed of a heat exchanger having a vacuum pump to.

However, the prior art has a disadvantage in that the energy generated while driving the heat exchanger is not effectively utilized, and thus, the driving cost and energy consumption of the device are so large that the maintenance cost and driving of the device are expensive.

An object of the present invention is to solve the problems of the prior art, to provide a sludge vacuum drying apparatus and method that can efficiently utilize the energy generated while driving the heat exchanger, thereby lowering the driving cost of the device.

In the present invention, the vacuum does not mean a complete vacuum, but a concept including a pressure lower than atmospheric pressure (for example, 0.1 atmosphere to 0.9 atmosphere or 0.2 atmosphere to 0.8 atmosphere). In addition, in this invention, below atmospheric pressure (or what is vacuum) narrowly contains 0.1 atmosphere-0.9 atmosphere, or 0.2 atmosphere-0.8 atmosphere, 0.3 atmosphere-0.7 atmosphere, 0.2-0.5 atmosphere, 0.6 atmosphere, for example. Concept. However, a perfect zero pressure exists theoretically but cannot be achieved in reality, so the term below atmospheric pressure or vacuum in the present invention does not include zero pressure.

Lowering the air pressure to dry the sludge lowers the boiling point, allowing the sludge to evaporate with less calories. Lowering the air pressure (for example, 0.02 atm) can reduce the heating point by reducing the boiling point, but a large-capacity vacuum pump must be used to reach the ultra low pressure, and much effort is required to seal the environment. Structurally rigid parts should be used to withstand mechanical forces caused by pressure differences from atmospheric pressure. On the contrary, if the air pressure is increased (for example, 0.9 atm), the pressure can be easily reached, but there is no big difference in boiling point, so there is a problem in that the advantages of vacuum drying cannot be fully utilized. Preferred dry pressure is any range of atmospheric pressure formed within the range of 0.1 atmosphere to 0.8 atmosphere.

In addition, in the present invention, the sludge broadly means a treatment object containing water to be treated by the apparatus of the present invention, and is not limited to sludge in a dictionary meaning.

The sludge vacuum drying apparatus according to the present invention for achieving the above object of the present invention is discharged after the sludge introduced from the input tank (1) is heated and dehydrated at a pressure below atmospheric pressure while passing through the drum (3) In the sludge vacuum drying apparatus to be moved to, the conveying means comprising a rotating shaft 10 for rotating the power of the motor (7), and a conveying screw 12 for rotating the sludge while rotating together with the rotating shaft (10) (T); Heating means (20) for heating the sludge in the drum (3) by transferring heat into the drum (3); And due to the heating of the sludge cooled with heat of vaporization of the refrigerant circulating in the drum 3, the water vapor (H ₂ O) flows through the induction pipe 25 and then generated by including a liquid evaporation (32) which functions to Cold trap part 30; A compressor (40) for compressing the refrigerant (vapor state) passed through the evaporator (32) into a high temperature and high pressure gas; And a vacuum pump 9 for reducing the internal pressure of the drum 3 to a pressure below atmospheric pressure.

In addition, the transfer means (T) is formed with a refrigerant pipe 11 through which fluid flows, and the refrigerant gas of high temperature compressed by the compressor 40 is supplied to one end of the refrigerant pipe 11. After being cooled through heat exchange with the surrounding sludge, it is discharged to the other end of the refrigerant pipe 11, and then flows back into the evaporator 32 through the expansion valve 50.

Hereinafter, the configuration and operation of the sludge vacuum drying apparatus according to the present invention will be described in detail according to the embodiment shown in the accompanying drawings.

1 is a block diagram of a sludge vacuum drying apparatus according to an embodiment of the present invention.

The sludge vacuum drying apparatus according to the present invention is moved to the discharge tank 5 after the sludge introduced from the input tank 1 is heated and dehydrated at a pressure below atmospheric pressure while passing through the drum 3. The input tank 1 or the discharge tank 5 may be configured in the hopper type to allow the discharge discharge, the lower portion of the discharge tank 5 is provided with a discharge valve (8) that is opened during discharge.

The drum (3) is formed in a cylindrical shape as a whole to facilitate the rotation of the rotating shaft (10) or the feed screw (12) provided and to facilitate the transport of the sludge.

The sludge vacuum drying apparatus according to the present invention includes a rotary shaft 10 that rotates with the power of the motor 7, and a transfer screw 12 that rotates the sludge while rotating together with the rotary shaft 10. The motor 7 is preferably a hydraulic motor generating large power and may include additional power transmission mechanisms including gears, belts, chains and the like.

Inside the transfer means (T), a space through which the refrigerant passes, that is, a refrigerant pipe is formed. Preferably, as shown, the conveying screw 12 is provided on the outer periphery of the rotary shaft 10 and the refrigerant pipe 11 is the rotary shaft 10 is formed therein. The rotating shaft 10 and the conveying screw 12 are largely named as the conveying means (T).

The transfer means (T) is a refrigerant pipe 11 is configured so that the refrigerant passes through, the condenser function (cooling the refrigerant) from the standpoint of the refrigerant, and at the same time a heat exchanger for heating the low temperature sludge by the heat of the high temperature refrigerant ( Or heating device) function.

The sludge vacuum drying apparatus according to the present invention includes a heating means 20 for heating the sludge inside the drum 3 by transferring heat into the drum 3. In order to efficiently transfer heat to the sludge, the heating means 20 is preferably provided on the outer circumference of the drum (3).

The cold trap unit 30 has a function of cooling and liquefying water vapor (H ₂ O) generated in the drum 3 due to the heating of the sludge and introduced through the induction pipe 25 to the vaporization heat of the circulating refrigerant. do. Thus, it comprises an evaporator 32 in which the refrigerant is vaporized.

That is, when the sludge of the drum 3 is heated, the water contained therein evaporates and the vaporized water vapor is moved to the cold trap unit 30 through the induction pipe 25 by the suction force of the vacuum pump 9 and the cold trap unit ( 30) quenches and liquefies water vapor to prevent or reduce the increase in pressure due to water vapor evaporation. The refrigerant passing through the evaporator 32 is vaporized and this heat of vaporization is supplied from water vapor. In other words, steam is trapped by the heat of vaporization of a cold refrigerant.

The sludge vacuum drying apparatus according to the present invention includes a compressor 40 for compressing a refrigerant (vapor state) passed through the evaporator 32 into a high temperature and high pressure gas, and a pressure for reducing the internal space of the drum 3 to a pressure below atmospheric pressure. And a vacuum pump 9.

In the conveying means T including the rotating shaft 10 or the rotating shaft 10 and the conveying screw 12, a refrigerant pipe 11 through which a fluid flows is formed, and the high temperature compressed by the compressor 40 is provided. Refrigerant gas is supplied to one end of the refrigerant pipe (11) of the rotary shaft (10).

In the present invention, the refrigerant pipe 11 provided on the rotating shaft 10 or the conveying means (T) refers to an empty space formed across the inside of the rotating shaft (10) or the conveying means (T), and serves as a piping function. The shape of the space is not limited. The conveying means (T) is a means for conveying sludge in one direction while rotating, and will generally include a rotating shaft (10) and a conveying screw (12).

The refrigerant is cooled through heat exchange with the surrounding sludge and then discharged to the other end of the refrigerant pipe 11, and is then introduced to the evaporator 32 via the expansion valve 50 again.

Cold trap unit 30 will be described in more detail. The cold trap unit 30 which cools and liquefies the vaporized heat of the refrigerant circulating through the induction pipe 25 to liquefy the evaporator 32 and a water tank 34 storing water generated by the liquefaction of water vapor. And a drain valve 35 for discharging the water stored in the water tank 34.

The direction in which the refrigerant flows and the position of the vacuum pump 9 will be described.

Preferably, the high temperature refrigerant flowing through the internal space of the rotary shaft 10 after passing through the compressor 40 moves opposite to the sludge conveying direction moved by the conveying screw 12. In addition, the vacuum pump 9 is preferably connected to the cold trap unit 30 on the opposite side of the induction pipe 25 connecting the drum 3 and the cold trap unit 30.

Hereinafter, the configuration of the evaporator 32 will be described in more detail.

Figure 2a is a block diagram of an evaporator according to an embodiment of the present invention, Figure 2b is an exploded perspective view of the spiral tube of the evaporator according to an embodiment of the present invention, Figure 2c is a cross-sectional view of the evaporator according to an embodiment of the present invention to be.

The evaporator 32 is preferably formed with an air inlet 111 and an air outlet 112, and a lower portion of the evaporator 32 and a hollow enclosure 110 communicating with the water tank 34 and a refrigerant inlet across the enclosure 110. And a spiral tube 120 having a coolant outlet 121 and a coolant outlet 121 '. However, in the present invention, it is obvious that the shape of the evaporator 32 is not limited to the above.

More preferably, at least one auxiliary spiral tube 130 is provided inside the spiral tube 120 to increase the heat exchange rate.

Hereinafter, the sludge vacuum drying method according to the present invention will be described.

In the sludge vacuum drying method according to the present invention, the sludge is heated under atmospheric pressure by evaporation of water contained in the sludge while being transported by a conveying means including a conveying screw that rotates by feeding the sludge to the drum 3 to dry the sludge. In the vacuum drying method, the water vapor (H ₂ O) generated by heating is liquefied by cooling with the heat of cooling of the evaporator 32 (according to the refrigerant vaporization) so that the pressure of the drum and the cold trap part is atmospheric pressure as the output of the limited vacuum pump. Maintaining below; And a compression step of compressing the refrigerant introduced from the evaporator into a gas of high temperature and high pressure.

In addition, by forming a refrigerant pipe through which the refrigerant can flow inside the transfer means (T), by introducing a gas of high temperature and high pressure compressed by the compressor into the refrigerant pipe formed in the transfer means (T), Condensing the refrigerant by heat exchange with the sludge at low temperature and heating the sludge with a high temperature refrigerant to increase the thermal efficiency and supply the remaining heat required for heating the sludge to the heating means formed outside the drum. It is done.

The operation of the sludge vacuum drying apparatus according to the present invention having such a configuration will be described.

The sludge is heated to below atmospheric pressure while being transported by a conveying means including a conveying screw that rotates by feeding the drum 3 to evaporate moisture contained in the sludge.

At this time, the heating is performed not only by the heating means 20 but also by the conveying means T through which a high-temperature refrigerant flows. In this way, the conveying means (T) serves as a sludge conveying function and at the same time a condenser function.

When the sludge of the drum 3 is heated, the water contained therein evaporates and the vaporized water vapor is moved to the cold trap unit 30 through the induction pipe 25 by the suction force of the vacuum pump 9 and the cold trap unit 30 By cooling and liquefying the water vapor prevents or reduces the increase in pressure due to water vapor evaporation. The refrigerant passing through the evaporator 32 is vaporized and this heat of vaporization is supplied from water vapor. In other words, steam is trapped by the heat of vaporization of a cold refrigerant.

The low pressure refrigerant passing through the evaporator 32 passes through the compressor 40 and later flows into the refrigerant pipe of the transfer means T for simultaneously performing the condenser function.

The vacuum pump 9 forms a vacuum (less than a maximum pressure) in the drum 3, the evaporator 32, the induction pipe 25, and the like, and prevents an additional pressure increase to maintain a certain level of pressure in the drum 3. Keep it as

Although the present invention has been described in connection with the above-mentioned preferred embodiment, the scope of the present invention is not limited to the embodiment, various modifications and variations will be possible.

According to the present invention solves the problems of the prior art, there is provided a sludge vacuum drying apparatus and method that can efficiently utilize the energy generated while driving the heat exchanger, thereby lowering the driving cost of the device.

The spiral heat exchanger unique to the present invention makes it possible to provide an evaporator capable of efficient heat exchange in a narrow space.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, the scope of the present invention is not limited to these embodiments, and the scope of the present invention is defined by the following claims, and equivalent scope of the present invention. It will include various modifications and variations belonging to.

The reference numerals set forth in the claims below are merely to aid the understanding of the present invention, not to affect the interpretation of the scope of the claims, and the scope of the claims should not be construed narrowly.

Claims (6)

In the sludge vacuum drying apparatus, the sludge introduced from the input tank (1) is heated and dehydrated at a pressure below atmospheric pressure while passing through the drum (3) and then moved to the discharge tank (5). A conveying means (T) comprising a rotating shaft (10) rotating with the power of the motor (7) and a conveying screw (12) for rotating the sludge and rotating together with the rotating shaft (10); Heating means (20) for heating the sludge in the drum (3) by transferring heat into the drum (3); A cold including an evaporator 32 generated from the drum 3 due to the heating of the sludge and cooling the water vapor H ₂ O introduced through the induction pipe 25 to liquefy by cooling the vaporized heat of the refrigerant circulating. A trap part 30; A compressor (40) for compressing the refrigerant (vapor state) passed through the evaporator (32) into a high temperature and high pressure gas; It comprises a; vacuum pump (9) for reducing the internal space of the drum (3) to a pressure below atmospheric pressure The conveying means (T) is formed with a refrigerant pipe (11) through which fluid can flow, and the high temperature refrigerant gas compressed by the compressor (40) is supplied to one end of the refrigerant pipe (11) and then surrounding Sludge vacuum drying apparatus, characterized in that the sludge is cooled through heat exchange and then discharged to the other end of the refrigerant pipe (11), and then flows back into the evaporator (32) through the expansion valve (50). The method of claim 1, The cold trap unit 30 for cooling and liquefying with vaporization heat of the refrigerant circulating through the water vapor introduced through the induction pipe 25 has an evaporator 32 and a water tank 34 storing water generated by the liquefaction of water vapor. And, the sludge vacuum drying apparatus comprising a drain valve 35 for discharging the water stored in the water tank (34). The method of claim 2, The evaporator 32 has an air inlet 111 and an air outlet 112 is formed, the lower portion is a hollow housing 110 in communication with the water tank 34, Sludge vacuum drying apparatus characterized in that it comprises a spiral pipe 120 is formed across the enclosure 110 and the refrigerant inlet 121 and the refrigerant outlet 121 '. The method of claim 3, Sludge vacuum drying apparatus, characterized in that at least one auxiliary spiral tube 130 is provided inside the spiral tube (120). The method of claim 1, After passing through the compressor 40, the high temperature refrigerant flowing through the inner space of the rotating shaft 10 moves in the opposite direction to the sludge conveying direction moved by the conveying screw 12, Sludge vacuum drying apparatus, characterized in that the vacuum pump (9) is connected to the cold trap unit 30 on the opposite side of the induction pipe (25) connecting the drum (3) and the cold trap unit (30). In the sludge vacuum drying method of drying the sludge by heating the sludge to below the atmospheric pressure while transporting the sludge by the conveying means (T) including the feeding screw which rotates by feeding the drum 3, Liquefying the water vapor generated by heating (H ₂ O) with cooling heat of the evaporator to maintain the pressure of the drum and the cold trap portion below atmospheric pressure as the output of a limited vacuum pump; It comprises a compression step of compressing the refrigerant introduced from the evaporator into a gas of high temperature and high pressure, The sludge having a relatively low temperature is formed by forming a refrigerant pipe through which the refrigerant flows, and introducing a high-temperature, high-pressure gas compressed by the compressor into the refrigerant pipe formed in the transfer means. Sludge vacuum drying, characterized by condensing the refrigerant by heat exchange of heat and simultaneously heating the sludge with a high temperature refrigerant, increasing the thermal efficiency and supplying the remaining heat required for heating the sludge to the heating means formed outside the drum. Way.

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