KR101481759B1 - Apparatus for drying sewage sludge by vaccum and method for manufacturing solid fuel with sewage sludge by vaccum - Google Patents

Abstract

The present invention relates to an apparatus for drying sewage sludge using vacuum and to a manufacturing method of solid fuel with sewage sludge. The apparatus for drying sewage sludge comprises a hopper for inputting sewage sludge; a drying chamber connected to the hopper and having an accommodation space; a conveying means installed within the drying chamber and conveying the sewage sludge to the rear end of the drying chamber; heat medium oil arranged in the lower space of the drying chamber; a heater for heating the heat medium oil; a vacuum pump connected to the drying chamber and suctioning the air within the drying chamber; and a cold trap positioned between the drying chamber and the vacuum pump, and having a heat exchange pipe for flowing a refrigerant to condense the vapor in the air suctioned from the inside of the drying chamber. The sewage sludge input into the hopper is dried by removing the moisture by the heat transferred by the heated heat medium oil within the drying chamber. According to the composition, the sewage sludge is dried by heat-exchanging with heat medium oil heated within the drying chamber, which has a lower pressure by the vacuum pump suctioning, thereby rapidly and efficiently drying the sewage sludge containing a high content of water at a low cost. Furthermore, the apparatus for drying sewage sludge using vacuum can rapidly discharge the vapor evaporated by the vacuum pump to outside, and manufacture solid fuel by forming pellets with the dried sewage sludge.

Description

TECHNICAL FIELD The present invention relates to a sewage sludge drying apparatus using a vacuum and a sewage sludge sludge by vaccum,

The present invention relates to a sewage sludge drying apparatus using a vacuum and a sewage sludge solid fueling method.

Conventionally, sludge generated mainly in a sewage treatment process has been subjected to marine dumping or landfilling. However, marine dumping is prohibited in order to protect the environment, landfill sites are limited, and disposal is becoming increasingly difficult.

So, in order to extend the life of the landfill, the sludge is incinerated to reduce the volume of the sludge so that the ash is buried or dried sludge is used for soil improvement.

In the case of general sewage sludge, the liquid content is high up to a water content of about 100 to 90%, and the viscosity is low. When the water content is about 90 to 85%, the slurry is in a liquid state although its viscosity is high and its fluidity is bad. When the water content is about 85 to 75%, the fluidity disappears in the paste state, but when the temperature is raised, it becomes closer to the slurry state. Further, when the water content is 75% or less, it becomes a cake state showing a state of a solid, and it becomes easy to granulate. When the water content is 30% or less, the shape becomes close to powder.

It is general that the dehydrated sludge or the like has a moisture content as high as 85% to 75% and is inconvenient to handle, so that it is subjected to a drying treatment so that the water content becomes 40% or less. Such a drier for drying sludge is generally used as an indirect heat dryer in which steam is filled in an air stream dryer or a steam jacket for blowing hot air and dried, and the water in the sludge is evaporated and dried using latent heat of steam.

In these dryers, the sludge to be dried is small granulated, and the larger the surface area, the more efficient the heat transfer. When the moisture content of the dried sludge is high, the sludge is hardly granulated so that only the surface of the sludge is dried and the inside of the sludge is not evaporated and the inside of the dryer is closed with the sludge, have.

Generally, the surplus sludge generated in the sewage treatment has a water content of about 99%, and the sludge is mechanically squeezed with a sludge dehydrator to bring the water content to about 80%, and then the sludge is added to the drier to perform the drying treatment.

However, since a meal of a general household becomes high-calorie, the concentration of the organic matter of the excess sludge generated in the sewage treatment increases year by year, so that the dewatering performance is lowered and the water content of the dewatered cake tends to increase. As a result, even if the dewatering cake is directly put into the dryer, stable operation can not be performed.

In this case, the surface of the object to be dried is covered with an incineration material having a low moisture content or dried sludge, or is applied to the entire surface to prevent the object to be dried from being attached to the inside of the apparatus.

In addition, a portion of the dried dried material is mixed with the dried sludge at the input side of the drier, thereby lowering the viscosity of the dried object to improve dispersibility.

However, this method has a problem in that not only the processing capability of the dryer is lowered but also the equipment is complicated due to facilities for returning a part of the discharged dried material to the input side of the dryer, thereby increasing the facility cost.

Korean Patent Application No. 10-1999-0013884

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a sewage sludge drying apparatus and a sewage sludge solid fuel making method using a vacuum capable of quickly and efficiently drying sludge having a high water content at a low cost and solidifying it into solid fuel There is a purpose.

According to an aspect of the present invention, there is provided a sewage sludge drying apparatus comprising: a hopper into which sewage sludge is introduced; A drying furnace connected to the hopper and having a receiving space; Conveying means installed in the drying furnace to convey the sewage sludge to the rear end of the drying furnace; A heating medium oil disposed in a lower space of the drying furnace; A heater for heating the thermal oil; A vacuum pump connected to the drying furnace to suck air in the drying furnace; A cold trap disposed between the drying furnace and the vacuum pump and having a heat exchange pipe through which the refrigerant flows to condense steam in the air sucked from the drying furnace; And the sewage sludge which is introduced into the hopper is dried by removing moisture by heat transfer by the heated heat medium oil in the drying furnace.

A crusher connected to the rear end of the drying furnace to crush the dried sewage sludge; A pellet molding machine connected to the crusher to mold the sewage sludge into pellets; .

A washing tub connected to a lower portion of the cold trap to filter condensed water in the cold trap; An oil mist collector connected to the vacuum pump to remove oil or the like contained in the air; A cooling device connected to the cold trap and having an expansion valve and a compressor; .

Also, a mesh net positioned below the drying furnace and capable of passing heat medium oil but not allowing sewage sludge to pass through; .

The drying furnace includes a first gate valve disposed at a front end of the drying furnace to airtightly close the inside of the drying furnace, and a second gate valve disposed at a rear end of the drying furnace.

According to another aspect of the present invention, there is provided a sewage sludge drying apparatus comprising: a hopper into which sewage sludge is introduced; A drying furnace connected to a lower portion of the hopper and having a receiving space; A heating medium oil disposed in a lower space of the drying furnace; A heater for heating the thermal oil; A vacuum pump connected to the drying furnace to suck air in the drying furnace; A cold trap disposed between the drying furnace and the vacuum pump and having a heat exchange pipe through which the refrigerant flows to condense steam in the air sucked from the drying furnace; And the sewage sludge introduced into the drying furnace is dried by removing moisture by heat transfer by the heated heat medium oil in the drying furnace.

According to another aspect of the present invention, there is provided a sewage sludge solidification fueling method comprising the steps of injecting sewage sludge into a drying furnace; Sucking air inside the drying furnace by a vacuum pump; Removing moisture from the sewage sludge by heat transfer by heated heat medium oil disposed in a lower space of the drying furnace; Crushing the water-removed sewage sludge in a crusher; Molding the pulverized sewage sludge into a pellet shape; .

According to the present invention, the sewage sludge is dried by heat exchange with the heating medium oil heated inside the drying furnace which is sucked by the vacuum pump and reduced in pressure, so that the sludge having a high water content can be dried quickly and efficiently at a low cost, It is possible to provide a sewage sludge drying apparatus using a vacuum and a sewage sludge solid fueling method capable of solidifying fuel by pelletizing the dried sludge while rapidly discharging the evaporated steam to the outside.

1 is a view showing the construction of a sewage sludge drying apparatus according to an embodiment of the present invention.
Fig. 2 is a view showing in detail the drying furnace portion of the sewage sludge drying apparatus of Fig. 1; Fig.
3 is a view for explaining a drying process using a vacuum in the sewage sludge drying apparatus of FIG.
4 is a view for explaining the process of pelletizing the sewage sludge dried in the sewage sludge drying apparatus of FIG.
FIG. 5 is a view showing the washing tub in detail in the sewage sludge drying apparatus of FIG. 1; FIG.
Fig. 6 is a view for explaining the configuration of a cooling apparatus in the sewage sludge drying apparatus of Fig. 1;
7 is a block diagram illustrating a sewage sludge solidification fueling method according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements throughout. The same reference numerals in the drawings denote like elements throughout the drawings.

Fig. 1 is a view showing the construction of a sewage sludge drying apparatus using vacuum (hereinafter, a sewage sludge drying apparatus) according to an embodiment of the present invention. Fig. 2 is a view showing in detail the drying furnace portion of the sewage sludge drying apparatus of Fig. 1; Fig. 3 is a view for explaining a drying process using a vacuum in the sewage sludge drying apparatus of FIG. FIG. 4 is a view for explaining a process in which the sewage sludge dried in the sewage sludge drying apparatus of FIG. 1 is pelletized. FIG. 5 is a view showing the washing tub in detail in the sewage sludge drying apparatus of FIG. 1; FIG. Fig. 6 is a view for explaining the configuration of a cooling apparatus in the sewage sludge drying apparatus of Fig. 1;

The sewage sludge drying apparatus 100 includes a hopper 110, a drying furnace 120, a conveying means 130, a heating medium oil 140, a heater 141, a vacuum pump 180, a cold trap 150, A cleaning tank 170, an oil mist precipitator 185, a crusher 191, a pellet molding machine 192, and the like.

The hopper 110 has a large inlet so that sewage sludge (hereinafter, sludge) can be injected. The width of the hopper 110 generally decreases toward the bottom, but is not limited to such a shape as long as the sludge 1 can be fed and fed to the bottom. The hopper 110 may be provided with a lid 111.

A roller portion 112 may be disposed under the hopper 110. The roller unit 112 is disposed in the hopper 110 and forms sludge into a predetermined shape and sends it to the drying furnace 120. The roller unit 112 is formed of a pair of rollers, and the sludge can be transferred between the rollers to have a constant thickness. The sludge 1 may be shaped into a predetermined shape in a pulverizer or an extruder and then introduced into the hopper 110 before being injected into the hopper 110.

The drying furnace 120 is connected to the hopper 110 and has a receiving space therein. The drying furnace 120 is directly connected to the lower portion of the hopper 110 so that the sludge introduced into the hopper 110 can be immediately dropped into the drying furnace 120 through the roller portion 112. The drying furnace 120 and the hopper 110 are not separated from each other and the inlet of the drying furnace 120 may be in the form of a hopper 110. [

The drying furnace 120 may include a first gate valve 121 disposed at the front end and a second gate valve 122 disposed at the rear end. The first gate valve 121 and the second gate valve 122 can hermetically close the inside of the drying furnace 120. [ When the sludge 1 is introduced into the drying furnace 120, the first gate valve 121 may be in the open state and the second gate valve 122 may be in the closed state.

The transfer means 130 is installed inside the drying furnace 120 to transfer the sludge 1 to the rear end of the drying furnace 120. The conveying means 130 may be constituted by a conveying screw. The conveying means 130 may have a structure in which the shaft 131 is rotated by the motor 132 to transfer the sludge to the rear end by the drying furnace 120.

The heating medium oil 140 is disposed in the lower space of the drying furnace 120 and is heated by the heater 141. The thermal oil 140 may be a waste cooking oil, a soybean oil, a perilla oil, a heavy oil, a light oil, or the like, preferably a waste cooking oil. The temperature of the thermal oil 140 may be 110 ° C or higher, preferably 140-160 ° C. The temperature of the heating medium oil 140 may be 140 ° C or higher in order to quickly vaporize the moisture contained in the sludge. When the temperature of the heating medium oil 140 is 160 ° C or higher, the drying efficiency of the sludge It does not rise sufficiently and becomes uneconomical. The temperature of the thermal oil 140 can be appropriately selected depending on the amount of the sludge 1 to be charged, the component of the sludge 1, and the like.

In the drying process of the sludge (1), water may be contained in the thermal oil (140). In order to separate moisture contained in the thermal oil 140, the lower part of the drying furnace 120 may be connected to the oil water separator 144. After the sludge 1 is dried to a certain extent, the thermal oil 140 enters the oil separator 144 through the valve 143 to separate the moisture contained in the thermal oil 140. Oil separation can be done by using the difference in specific gravity between water and oil or by centrifugation. The separated water is received in the water storage tank 146 through the drain valve 145 and the pure heat oil 140 is returned to the inside of the drying furnace 120 by using the pump 147 in a state in which the valve 148 is opened Can be supplied.

The vacuum pump 180 sucks air in the drying furnace 120 to make the inside of the drying furnace 120 lower than 1 atm. As shown in Fig. 3, when the vacuum pump 180 performs the suction action, both the first gate valve 121 and the second gate valve 122 are closed.

The vacuum pump 180 can suck air in the drying furnace 120 through a connection pipe 123 connected to the drying furnace 120. The air sucked by the vacuum pump 180 may be sucked through the connecting pipe 181 connected to the cold trap 150 after passing through the cold trap 150 through the connecting pipe 123. As the vacuum pump 180, for example, a water-sealed vacuum pump may be used.

Moisture contained in the sludge 1 is evaporated at 100 ° C under atmospheric pressure, but when the pressure in the drier 120 is lowered, the evaporation temperature is lowered. For example, at 92.51 mmHg it evaporates at 50 ° C and at 4.58 mmHg evaporates at 0 ° C. In this embodiment, the degree of vacuum applied to the drying furnace 120 can be appropriately selected in accordance with the state of the sludge 1.

In the present invention, by reducing the pressure in the drying furnace 120 by the vacuum pump 180, the moisture contained in the sludge 1 can be evaporated at 100 ° C or less, for example, at 50 ° C. Further, the vacuum pump 180 allows the evaporated steam to be discharged to the outside of the drying furnace 120 well.

The sludge is conveyed by the conveying means 130 in the drying furnace 120 and passes over the heated heating medium oil 140 while the pressure in the drying furnace 120 is lowered by the vacuum pump 180. [ Accordingly, the moisture contained in the sludge is directly vaporized by the heat transfer by the heated heating oil 140.

The moisture contained in the sludge 1 is vaporized and rises above the drying furnace 120. This water vapor passes through the cold trap 150 through the connection pipe 123 by the suction action of the vacuum pump 180, .

The thermal oil 140 penetrates not only the surface of the agglomerated sludge but also the inside of the sludge so that the moisture in the interior can be quickly vaporized. The sludge that has passed through the thermal oil (140) may be crispy as it is fried in oil. Accordingly, there is no problem that the sludge is conventionally attached to the apparatus by the viscosity.

Conventionally, the method of drying the sludge by steam has a problem in that a considerable amount of moisture is contained in the sludge even after drying because the drying is costly and only the surface is dried. Further, when a step of covering the surface of the dried sludge with a low moisture content incineration ash or dried sludge is added in order to prevent the sludge having viscosity from being adhered to the apparatus, the apparatus becomes complicated and the facility cost is increased.

On the contrary, the sludge drying method using the thermal oil 140 of the present invention makes it possible to completely remove moisture contained in the sludge at a low cost.

The mesh net 142 is located below the drying furnace 120 and allows the passage of the thermal oil 140 but not the sludge. Accordingly, the heat medium oil 140 that transfers heat to the sludge can be dropped through the mesh net 142 to control the heat medium oil 165 contained in the dried sludge. The mesh network 142 may be positioned below the transport screw 130. The arrangement of the conveying means 130, the heating medium oil 140, and the mesh net 142 can be appropriately selected or changed as required by those skilled in the art.

3, when the inside of the drying furnace 120 is sucked by the vacuum pump 180, the moisture contained in the sludge in the drying furnace 120 evaporates and passes through the cold trap 150. The cold trap 150 is located between the drying furnace 120 and the vacuum pump 180.

In the cold trap 150, a heat exchange pipe 151 through which refrigerant flows is formed. The water vapor contained in the air sucked from the drying furnace 120 is heat-exchanged with the refrigerant through the heat exchange pipe 151 and condensed. A plurality of heat transfer members 152 may be attached to the heat exchange pipe 151. The temperature in the cold trap 150 may be, for example, about 0 ° C to 6 ° C.

The condensed water condensed in the cold trap 150 is collected at the lower portion of the cold trap 150 and the lower portion of the cold trap 150 can be connected to the cleaning bath 170. The cleaning tank 170 serves to purify the condensed water by filtering contaminants contained in the condensed water.

5, an active carbon layer 171, a filtration media layer 172, a gravel layer 173, and a sand layer 174 may be sequentially stacked on the cleaning tank 170 from the top. The filtration media layer 172 may be a porous material that collects solid particles contained in the condensed water, and may be composed of fibers, nonwoven fabric, filter paper, porous metal, plastic, or the like.

The solid particles contained in the condensed water can be adsorbed while passing through the activated carbon layer 171, the filtration media layer 172, the gravel layer 173 and the sand layer 174 in order. And can be stored. The water stored in the water storage tank 176 may be used for discharging or washing.

In the process of sucking the air in the drying furnace 120 by the vacuum pump 180, the air contains oil and various contaminants. That is, since many sewage sludge contains odor causing substances, it may cause environmental pollution if it is directly discharged into the air. For this purpose, the oil mist precipitator 185 is connected to the vacuum pump 180 to remove oil and contaminants contained in the air.

In the oil mist dust collector 185, adsorbent materials capable of adsorbing oil and pollutants are disposed. In addition, moisture contained in the air is also filtered and collected at the lower portion of the oil mist precipitator 185. Moisture collected at the lower part of the oil mist precipitator 185 can be discharged to the outside through the drain cock 184. [ Further, the air from which the pollutants are removed can be exhausted to the atmosphere through the exhaust pipe 186. The oil mist precipitator 185 may be omitted if necessary.

Referring to FIG. 6, a cooling device 160 is disposed to flow the refrigerant into the heat exchange pipe 151 in the cold trap 150. The cooling device 160 is connected to the heat exchange pipe 151 and includes an expansion valve 162 and a compressor 161. The construction of the cooling cycle of the refrigerant flowing in the heat exchange pipe 151 will be described below.

The refrigerant expanded at the expansion valve 162 is lowered in pressure and flows through the heat exchange pipe 151 in the cold trap 150. At this time, the refrigerant is heat-exchanged with the air passing through the cold trap 150, and evaporation occurs. On the other hand, the steam in the air sucked in the drying furnace 120 by the vacuum pump 180 is heat-exchanged with the refrigerant through the heat exchange pipe 151 in the cold trap 150 to be condensed.

 The refrigerant evaporated through the heat exchange pipe 151 is compressed by the compressor 161, and a part of the refrigerant is liquefied. Next, the refrigerant compressed in the compressor 161 discharges heat while exchanging heat with the outside air, and is condensed into a liquid refrigerant state. The condensed refrigerant again flows into the expansion valve 122. In the figure, the arrows indicate the flow path of the refrigerant.

The sludge 1 is dried in the drying furnace 120 by the suction action by the vacuum pump 180 and the heat transfer by the heat medium oil 140 and the moisture contained in the sludge 1 passes through the connection pipe 123 The second gate valve 122 is opened and the sludge 1 can be discharged to the outside of the drying furnace 120 by the conveying means 130. [

The sludge exiting the drying furnace 120 passes through the crusher 191. The crusher 191 is connected to the rear end of the drying furnace 120 to finely crush the dried sludge. The sludge that has exited the drying furnace 120 is removed from the heat transfer due to the heat medium oil 140, and the moisture content can be reduced to almost 0%.

The crushed sludge in the crusher 191 moves to the pellet molding machine 192. The pellet molding machine 192 shapes the pulverized sludge into a pellet shape. Sludge formed in pellet form can be used as fuel in thermal power plants and the like.

The sludge drying apparatus of the present invention is characterized in that the sludge is passed through the drying furnace 120 while the pressure inside the drying furnace 120 is lowered by the vacuum pump 180, It is possible to dry the sludge to a moisture content of about 0% quickly at a low cost. In addition, the moisture contained in the sludge 1 can be quickly discharged to the outside of the drying furnace 120 by the suction action by the vacuum pump 180.

In addition, when the sludge 1 is heat-exchanged with the thermal oil 140 in a state where the pressure inside the drying furnace 120 is lowered by the vacuum pump 180, moisture can be removed very quickly. Therefore, it is possible to reduce the time for the sludge 1 to contact with the thermal oil 140, and it is possible to keep the component of the thermal oil 140 contained in the dried sludge 1 to a minimum. Accordingly, the crushed sludge in the crusher 191 does not need to undergo a solid-liquid separation process for separating the thermal oil 140 component.

Hereinafter, the sewage sludge solidification method of the present invention will be described with reference to FIGS. 1 to 6. FIG. 7 is a block diagram illustrating a sewage sludge solidification fueling method according to an embodiment of the present invention.

First, the sludge is introduced into the drying furnace 120 (S10).

Next, the sludge is transferred to the rear end of the drying furnace 120 (S20).

Next, the air inside the drying furnace 120 is sucked by the vacuum pump 180 (S30).

Next, during the transfer of the sludge, moisture of the sludge is removed by heat transfer by the heated thermal oil 140 disposed in the lower space of the drying furnace 120 (S40). At this time, since the pressure inside the drying furnace 120 is lowered by the vacuum pump 180, the moisture contained in the sludge is vaporized at a temperature lower than 100 ° C, and the inside of the drying furnace 120 is filled with steam . At this time, the interior of the drying furnace 120 is continuously suctioned by the vacuum pump 180, and the water vapor contained in the air sucked by the vacuum pump 180 can be condensed while passing through the cold trap 150.

Next, the sludge from which moisture has been removed is pulverized in the pulverizer 191 (S50).

Next, the pulverized sludge is molded into a pellet shape in the pellet molding machine 192 (S60).

The sewage sludge solidification method described above may include all of the contents described above with respect to the sludge drying apparatus 100.

According to the sewage sludge solid fueling method described above, the sludge can be dried quickly at a low cost and the water content can be dried to almost 0%, and the sludge can be molded into pellets and used as fuel for a thermal power plant or the like. This makes it possible to effectively treat the sludge at low cost in the reality that marine dumping is prohibited and the processing cost of sludge becomes a problem.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention will be.

100: sewage sludge drying device
110: Hopper
120: drying furnace
121: first gate valve
122: second gate valve
130:
140: heat medium oil
141: Heater
150: Cold trap
160: Cooling unit
170:
176: Water tank
180: Vacuum pump
185: Oil mist precipitator
191: Crusher
192: pellet molding machine

Claims (7)

In the sewage sludge drying apparatus,
A hopper 110 into which sewage sludge is introduced;
A drying furnace (120) connected to the hopper (110) and having a receiving space;
A transfer screw 130 installed in the drying furnace 120 and transferring sewage sludge to a rear end of the drying furnace 120;
A heating medium oil 140 disposed in a lower space of the drying furnace 120;
A heater 141 for heating the thermal oil;
A mesh net 142 positioned below the feed screw 130 to allow passage of the heat medium but not the sewage sludge;
An oil water separator 144 connected to a lower portion of the drying oven 120 through a valve 143 to separate moisture contained in the heat medium oil;
A pump 147 for supplying again the heat medium oil separated from the oil-water separator 144 into the drying furnace 120;
A vacuum pump 180 connected to the drying furnace 120 to suck air in the drying furnace;
A cold trap (150) disposed between the drying furnace (120) and the vacuum pump (180) to form a heat exchange pipe through which the refrigerant flows to condense steam in the air sucked from the inside of the drying furnace (120);
A washing tub 170 connected to a lower portion of the cold trap 150 to filter condensed water in the cold trap 150;
An oil mist precipitator 185 connected to the vacuum pump 180 to remove oil contained in the air;
A cooling device 160 connected to the cold trap 150 and having an expansion valve 162 and a compressor 161;
A crusher 191 connected to the rear end of the drying furnace 120 to crush the dried sewage sludge;
A pellet molding machine 192 connected to the crusher 191 to mold the sewage sludge into a pellet shape;
Lt; / RTI >
The sewage sludge introduced into the hopper 110 is dried by removing heat by heat transfer by the heated heat medium oil in the drying furnace 120,
The drying furnace 120 includes a first gate valve 121 disposed at the front end of the drying furnace 120 so as to hermetically close the inside of the drying furnace 120 and a second gate valve 121 disposed at the rear end of the drying furnace 120, 2 gate valve (122). delete delete delete delete delete delete

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