JP2016095068A - Sludge drying processing method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sludge drying processing method and its device for removing liquid-like substance such as water, oil and the like from various kinds of sludge.SOLUTION: This invention basically provides a method for sludge drying and processing method in which sludge S is supplied to a reduced pressure processing tank 1 and an inside part of the reduced pressure processing tank 1 is processed in reduced pressure by an ejector pump 4 connected to the reduced pressure processing tank 1 through a condensation tank 2 and the sludge is indirectly heated under a state in which a boiling point of liquid-like substance in the sludge S is lowered to take out the liquid-like substance under its vapor state and subsequently the vapor is condensed and returned to its liquid state and stored in a condensation tank 2, thereby liquid substance is removed from the sludge S and dried.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sludge drying method and apparatus for removing liquid components such as water and oil from various types of sludge such as rolling sludge, cutting sludge and the like.

A large amount of cooling water used in the hot rolling process or metal cutting process at steelworks contains miscellaneous oil such as lubricating oil and grease, and solids such as scale and dust. For this reason, the used cooling water is reused as regenerated cooling water through a predetermined process, and a large amount of sludge is produced as a residue obtained from the regenerated cooling water. For example, hot rolled sludge (hereinafter referred to as “rolled sludge”) is composed of iron oxide, water, oil, etc., and is composed of iron content 40%, moisture 20%, oil content 5%, and other components 35%, It is a mud containing a solid having a particle size of about 50 μm. In addition, rolled sludge is a source of carbonyl sulfide (COS), carbon disulfide (CS ₂ ), and sulfur dioxide (SO ₂ ) and emits a foul odor. Therefore, rolling sludge is a solid prerequisite for reuse or disposal. The liquid needs to be separated and dried.

  Therefore, conventionally, the rolled sludge is often dehydrated and reduced in volume by sun drying, a belt press or the like and then discarded as industrial waste or reused as a cement raw material. Also, in order to reuse the rolled sludge as a raw material for steelmaking, in order to prevent steam explosions when introduced into the hot metal pretreatment furnace and to prevent clogging of the piping route, almost completely dry conditions (water content 1) %) To a powder form. For this reason, there is used means for drying by sun drying, belt press or the like and performing pretreatment, and further drying by baking with a rotary kiln or hot air drying with a hot air drying device.

  Further, there is also provided means for using the rolled sludge as an iron source and a heat source by supplying water to the rolled sludge instead of drying, heating it, adjusting the viscosity, and supplying it to the blast furnace (Patent Document 1). ).

JP 07-316674 A

  However, the firing means using the rotary kiln can be fired regardless of the physical properties of the sludge. However, since heavy oil or gas is used as the fuel, an exhaust gas treatment device is required. In addition, the drying means using a hot air drying device is to put rolled sludge in the furnace and apply hot air of about 350 ° C. while crushing to dry, so if the sludge contains combustibles such as oil, it will ignite. Since there is a fear, it is necessary to lower the temperature of hot air (reducing the processing amount). Therefore, in the conventional drying means using a rotary kiln or a hot air drying device, when the sludge has a high water content, dehydration is necessary as a pretreatment, which increases the scale of the facility and the fuel consumption. And because of the high-temperature treatment, it is necessary to treat the exhaust gas generated from oil and the like, and there is no countermeasure against sludge that has a problem of odor. Further, because of the high temperature treatment, it is not suitable for a process in which no alteration other than the liquid component to be removed from the sludge is recognized.

  On the other hand, the means shown in Patent Document 1 is not a means for drying the sludge, but adjusts the viscosity of the sludge by supplying water, so it cannot be used as a treatment means for discarding the sludge and can be reused. The use of is also specified.

  Therefore, the present invention solves the problems of the sludge treatment means described above, removes liquid components such as water and oil from various sludges, and dries them to facilitate treatment and reuse. It is an object of the present invention to provide a sludge drying method and apparatus for enabling it.

  In order to solve the above problems, the present inventor supplies sludge to a reduced pressure treatment tank, and decompresses the inside of the reduced pressure treatment tank with an ejector pump connected to the reduced pressure treatment tank through a condensing tank. By indirect heating with the boiling point of the liquid component lowered, the liquid component is taken out in the vapor state, and then the vapor is condensed, and then the liquid component is returned to the liquid state and stored in the condensing tank. Provided on the basis of a method for drying sludge that is removed and dried.

  Moreover, the structure which stirs the decompression processing tank hold | maintained under reduced pressure, the structure which injects a cooling liquid into the liquid component taken out from the decompression processing tank in the vapor state, liquefies it, and stores it in a condensing tank, from the decompression processing tank The liquid component taken out is supplied to a condensing tank set at a liquid temperature of 40 ° C. or lower, liquefied and stored, an ejector tank equipped with an ejector pump is connected to the condensing tank, and the liquid material stored in the ejector tank is By supplying the ejector pump as a driving fluid, a configuration in which the decompression processing tank is held under reduced pressure through a condensing tank and a configuration in which water is used as a liquid material stored in the ejector tank are provided.

  Moreover, the structure which hold | maintains a decompression processing tank under the reduced pressure of -0.07MPaG--0.096MPaG, the structure which uses water as a liquid substance stored in a condensation tank, The processed material which removed the liquid component from the sludge and dried And the sludge is rolled sludge, sludge, oil / water mixture or volatile organic compound (VOC) contaminated soil, and the liquid component contained in the sludge is water, oil or volatile organic compound (VOC) ) Is provided.

  And it is the sludge processing apparatus for implementing the above-mentioned sludge drying processing method, Comprising: The decompression processing tank which holds sludge under pressure reduction, the indirect heating apparatus of a decompression processing tank, and the condensation connected to the decompression processing tank A tank, a liquid material stored in the condensing tank, an ejector tank connected to the condensing tank, an ejector pump equipped in the ejector tank, and a liquid material stored in the ejector tank and supplied to the ejector pump as a driving fluid Provided is a sludge drying apparatus.

  In addition, the vacuum treatment tank is equipped with a sludge inlet and a discharge port for discharging the processed material after removing the liquid components from the sludge. Equipped configuration, as an indirect heating device, a configuration equipped with a hollow heating shaft in a vacuum treatment tank so as to be rotatable, a configuration in which a plurality of stirring blades are rotatably projected at regular intervals on the outer peripheral surface of the heating shaft, and indirect Provided is a configuration for supplying heated steam to a heating device.

  Furthermore, a structure that is equipped with a cooling liquid injection means for injecting the liquid material in the condensation tank as a cooling liquid to the pipe connecting the pressure reduction treatment tank and the condensation tank toward the condensation tank, and the liquid material in the condensation tank is subjected to the pressure reduction treatment. Provided is a configuration equipped with preheating means for preheating the sludge by supplying it to the sludge before being charged into the tank.

  According to the present invention described above, the sludge is treated under reduced pressure, and the liquid component is removed from the sludge in a vapor state by indirectly heating the sludge in a state where the boiling point of the liquid component in the sludge is lowered. By condensing the vapor and returning it to the liquid state again, the thermal efficiency is high and the drying process can be performed efficiently in a short time.

  When the liquid component in the sludge is water, it can be depressurized and evaporated at a low temperature, so that the oil content is less vaporized, and therefore the generation of exhaust gas is reduced. Even if it occurs, since it can be trapped in the condensing tank, it does not leak to the outside. Further, since the treatment is performed under reduced pressure, it is possible to treat at a temperature lower than the ignition point such as oil, and there is no fear of ignition. Since the reduced pressure treatment tank is indirectly heated in a sealed reduced pressure state, the sludge can be treated in any state and the sludge is not altered by heat.

  Most of the heat energy given to the sludge can be recovered as condensation latent heat in the condensation tank and can be reused for sludge preheating and the like. Since an ejector pump is used as the decompression means, even if steam or moisture is mixed in, no breakdown occurs and stable drying processing is possible. And since the vapor | steam taken out from the decompression processing tank is condensed and liquefied in a condensation tank, a gas volume becomes substantially zero and there is little load of an ejector pump.

  Furthermore, it is possible to reduce the volume by injecting the cooling liquid onto the steam taken out from the decompression tank and condensing the steam on the spot by forcing the steam into contact with the cooling liquid. In addition, the pressure reduction capability is improved by the pressure difference between the vacuum generated by the condensation and the flow rate of the coolant. In addition, even when the amount of generated steam is small, the constant flow rate can be maintained, and the effect of washing away with water can solve the powder accumulation in the pipe. Therefore, the rolled sludge can be efficiently dried in a short time to a completely dry state with a moisture content of less than 1%, and can be reused as a steelmaking raw material.

1 is a system diagram schematically showing a sludge drying treatment method and apparatus according to the present invention. Process explanatory drawing of this invention. The graph which shows the relationship between a pressure, a boiling point, and a specific volume. Graph showing the relationship between pressure and temperature / time. Graph showing the relationship between pressure and temperature / time.

  Embodiments of a sludge drying method and apparatus according to the present invention will be described below. The present invention maintains rolling sludge and other sludge under reduced pressure, and indirectly heats the sludge in a state where the boiling point of the liquid component in the sludge is lowered, so that liquid components such as water and oil are in a vapor state from the sludge. The liquid component is removed from the sludge by taking out and returning the vapor again to the liquid state after being taken out and dried.

  The present invention was developed on the occasion of drying treatment of rolled sludge composed of iron oxide, water, oil, etc., but the target sludge is not particularly limited and is dried containing a liquid component. Any sludge that is necessary is applicable. In the present invention, sludge (mud) refers to a substance in which a solid and a liquid are mixed, and is not particularly limited by the cause of generation or the contained components. Specific examples of sludge include rolled sludge, sludge, oil / water mixture or volatile organic compound (VOC) contaminated soil, and the liquid component contained in the sludge is water, oil or volatile organic compound (VOC). Is mentioned. There is no restriction on the liquid content of the liquid component, and all sludge with a high liquid content can be treated. Further, the degree of drying is not limited, and the treatment may be carried out until a predetermined dry state according to the purpose. Incidentally, when the rolled sludge is dried for the purpose of reusing it as an iron-making raw material, the purpose is to dry it to an absolutely dry state with a moisture content of less than 1%.

  FIG. 1 is a system diagram schematically showing a method and apparatus for drying sludge S according to the present invention, and FIG. 2 is a process explanatory diagram. In the figure, reference numeral 1 denotes a vacuum treatment tank, which is a hollow bowl-shaped cylindrical body having a volume for storing various sludges S to be dried therein, and has a sealed structure in order to keep the inside under a reduced pressure state. Therefore, it has strength that can withstand reduced pressure. A hollow heating shaft 5 for heating the decompression processing tank 1 is rotatably provided in the center of the decompression processing tank 1, and the outer peripheral surface of the heating shaft 5 is fixed to increase the thermal conductivity. A plurality of stirring blades 6 are rotatably provided at intervals. Reference numeral 7 denotes a motor, which is disposed outside the decompression processing tank 1 as a power source for rotationally driving the heating shaft 5.

  A heating jacket 8 is provided on the outer peripheral surface of the decompression processing tank 1 so as to cover the decompression processing tank 1, and the heating jacket 8 and the heating shaft 5 are heated by the heating source 9 and stored in the decompression processing tank 1. The sludge S is indirectly heated. In the illustrated example, a steam boiler is used as the heating source 9, heated steam is supplied from the heating source 9 to the heating shaft 5 through the supply pipe 10, and the heated steam supplied to the heating shaft 5 is supplied from the heating shaft 5. It returns to the steam boiler of the heating source 9 through the discharge pipe 11 and is heated again. The supply pipe 10 is branched in the middle of the supply pipe 10 to supply heated steam to the heating jacket 8. The heating steam supplied to the heating jacket 8 joins the discharge pipe 11 through the discharge pipe 11a, returns to the steam boiler of the heating source 9, and is heated again. In addition, 12 and 12a are steam traps for discharging the drains, which are installed in the discharge pipes 11 and 11a, respectively, and the drains collected from the steam traps 12 and 12a are supplied to the steam boiler of the heating source 9. It can be reused as raw water for heated steam.

  A raw material inlet 13 for supplying the sludge S is provided on the upper surface of the vacuum treatment tank 1 so as to be able to be sealed, and a product outlet 14 for discharging the processed product of the sludge S after drying is hermetically sealed at the bottom. Equipped as possible. Therefore, the heated steam supplied to the heating shaft 5 and the heating jacket 8 is indirectly heated while the sludge S is stirred while the inside of the reduced pressure treatment tank 1 is kept under reduced pressure, and the liquid component is vaporized. .

  A condensing tank 2 condenses the vapor of the liquid component of the sludge S taken out from the decompression processing tank 1, and reduces the load on the ejector pump 4 described later. Therefore, the condensing tank 2 is a container having a fixed volume with a sealed structure, and stores the liquid material 16 therein. Although it is appropriate to use water as the liquid material 16, when the liquid component contained in the sludge S is a substance that does not separate from water (for example, oil), the same substance (for example, oil) as the liquid component is used. It is preferable.

  The condensing tank 2 is connected to the decompression tank 1 through a pipe, and a large-diameter steam pipe 17 connected to the decompression tank 1 is piped to a reducer 18 that is a pipe joint. A small-diameter condensing pipe 19 is provided up to the inside. 20 is a pressure release valve installed in the steam pipe 17, and 21 is a pressure maintenance valve installed in the condensation pipe 19. Further, a shower pump 22 is installed at the bottom of the condensing tank 2 as a coolant injection means, and water or other liquid material 16 stored in the condensing tank 2 is passed through the shower pipe 23 into the steam pipe 17 or the reducer. The liquid 16 is supplied as a cooling liquid into the liquid 18 and sprayed so as to flow in the direction of the condensation pipe 19. A check valve 24 can supply the liquid 16 only in the direction of the reducer 18.

  By using the liquid material 16 stored in the condensing tank 2 in the same negative pressure system as the cooling liquid, the pressure in the decompression processing tank 1 is not increased, and the usage amount of the liquid material 16 is increased. There is nothing. Furthermore, since the liquid material 16 is cooled to a predetermined temperature or lower as described later, it is not necessary to cool it separately as a cooling liquid. The liquid 16 may be injected into the steam pipe 17 or the reducer 18, but when injected into the reducer 18, it is injected into the large diameter portion. There are no particular limitations on the injection direction and the injection nozzle of the liquid material 16 as long as the injected liquid material 16 can flow in the direction of the condensation pipe 19. Preferably, the steam pipe 17 or the reducer 18 is sprayed so as to form a water wall in the pipe cross section. When the steam pipe 17 or the reducer 18 is sprayed from the peripheral wall toward the peripheral wall facing the steam pipe 17 (for example, from below to the upper wall), the area where the steam comes into contact is widened, and condensation can be effectively performed. 17 or reducer 18 can be extensively cleaned. The supply amount of the liquid material 16 is not particularly limited as long as it can be circulated in the small-diameter condensing tank 2. Moreover, it is necessary to pay attention so that the spray of the liquid material 16 does not enter the reduced pressure treatment tank 1.

  As a result, condensation is promoted by forcibly bringing the steam taken out from the decompression tank 1 into contact with the cooling liquid, and the volume of the steam is reduced. Compared to the steam pipe 17 through which the steam flows, the pipe of the condensation pipe 19 The diameter can be greatly reduced. In the present embodiment using the decompression tank 1 capable of treating 1500 kg of sludge S at a time, it is necessary to use the steam pipe 17 having a pipe diameter of 300 mm. However, as the condensing pipe 19, a pipe diameter of 100 mm is sufficient. is there. Furthermore, the pressure reduction capacity of the pressure reduction treatment tank 1 can be increased by the pressure difference generated by the injection of the coolant and the pressure difference caused by the condensation. Furthermore, since the dust entrained by the steam can be trapped and washed away by the cooling liquid, even if the small-diameter condensing tube 19 is used, no blockage occurs.

  In the condensing tank 2 mainly intended for condensation, the temperature of the liquid 16 influences the condensation rate, so the temperature of the liquid 16 needs to be kept as low as possible. Since the temperature of the liquid body 16 is increased by the sensible heat and latent heat of the steam taken out from the sludge S, it is necessary to equip the inside or outside of the condensing tank 2 with a means for cooling the liquid body 16. By setting the liquid temperature in the condensing tank 2 to approximately 40 ° C. or lower, water vapor generated in the decompression processing tank 1 is condensed, and the ejector pump 4 can be made small. Therefore, in this embodiment, a circulation pump 25 is installed at the bottom of the condensing tank 2, and the liquid 16 stored in the condensing tank 2 is supplied to the preheating device 27 via the circulation pipe 26 to condense. The sludge S as a raw material is preheated at the temperature of the liquid 16 in the tank 2. A check valve 28 can supply the liquid 16 only in the direction of the preheating device 27. The liquid 16 that has been supplied to the preheating device 27 and released the heat is supplied to an appropriate cooling device 30 such as a cooling tower via a cooling pipe 29, cooled by appropriate means such as a shower ring, and the like via a return pipe 31. Circulate in the condensation tank 2. A predetermined amount of the sludge S preheated by the preheating device 27 is introduced into the decompression processing tank 1 from the raw material inlet 13 through the raw material supply pipe 32.

  Reference numeral 3 denotes an ejector tank, in which an ejector pump 4 is installed above, and a liquid material 34 as a drive fluid for the ejector pump 4 is stored therein. The liquid material 34 is the same as the liquid material 16. A drive pump 35 is installed at the bottom of the ejector tank 3, and the liquid 34 is supplied to the ejector pump 4 through a drive pipe 36. The ejector pump 4 injects the supplied liquid material 34 as a driving fluid from the nozzle toward the ejector tank 3 to reduce the flow rate of the liquid material 34 to increase the flow velocity, thereby forming a decompressed state by the venturi effect. Since the temperature of the liquid material 34 affects the degree of vacuum, it is necessary to keep the temperature of the liquid material 34 as low as possible. Therefore, it is preferable to equip the inside or the outside with a cooling mechanism.

  The ejector pump 4 is less expensive than a general vacuum pump and has a simple structure, so that the maintenance frequency is extremely low and it is resistant to failure. Above all, the steam itself can be sucked, and even if steam or moisture is mixed, it does not break down and can be stably dried. Furthermore, it is possible to maintain a plurality of decompression processing tanks 1 in a decompressed state with a single ejector pump 4, and it is possible to perform a drying process by switching the plurality of decompression processing tanks 1. Since the ejector pump 4 is connected so as to communicate with the inside of the condensing tank 2 through the communication pipe 37, the condensing tank 2 and the decompression processing tank 1 communicating with the condensing tank 2 are maintained in a decompressed state. Become. A check valve 38 is installed in the communication pipe 37 and allows the fluid to pass only in the direction of the ejector pump 4, thereby holding the condensing tank 2 and the decompression processing tank 1 in a decompressed state.

  In the case where the liquid component taken out from the sludge S is a harmful or odorous substance and decomposes at less than 1000 ° C., the liquid component that has passed through the condensing tank 2 and the ejector tank 3 is removed from the hot stove (not shown). It is also possible to decompose using Furthermore, a drainage storage tank (not shown) may be provided for each case where the condensing tank 2 and the ejector tank 3 overflow.

  A method for drying the sludge S using the sludge S drying apparatus will be described with reference to FIGS. First, as shown in step A, sludge S as a raw material to be dried is introduced into the decompression tank 1 from the raw material inlet 13 by a single processing amount. In this embodiment, in order to recycle it as an iron-making raw material, sludge S composed of 1500 kg of rolled sludge having a moisture content of 13.7% by weight was charged in order to dry it to an absolutely dry state with a moisture content of less than 1%. As will be described later, the sludge S may be preheated or other pretreatment as necessary.

  Next, as shown in step B, the sludge S is held under reduced pressure by reducing the pressure in the reduced pressure treatment tank 1. For decompression, the inside of the decompression tank 1 is hermetically sealed, and water or other liquid material 34 stored in the ejector tank 3 is supplied to the ejector pump 4 by driving the drive pump 35 to be ejected by the ejector tank. 3 is injected into 3 to form a reduced pressure state. Since the ejector pump 4 communicates with the condensing tank 2 held in a sealed state via the communication pipe 37, the inside of the condensing tank 2 is also kept in a reduced pressure state. Further, the condensing tank 2 communicates with the inside of the decompression processing tank 1 held in a sealed state via a condensing pipe 19, a reducer 18 and a steam pipe 17. Then, the pressure release valve 20 installed in the steam pipe 17 is closed, and the ejector pump 4 is driven in a state where the pressure maintenance valve 21 installed in the condensing pipe 19 is opened. The sludge S is kept in a state where the boiling point is lowered under reduced pressure.

The degree of the reduced pressure state of the reduced pressure treatment tank 1 is not particularly limited, but it is efficient for the drying treatment to maintain the reduced pressure at −0.07 MPaG to −0.096 MPaG. FIG. 3 is a graph showing the relationship between pressure and boiling point / specific volume, with the horizontal axis representing pressure (MPaG) and the vertical axis representing boiling point (° C.) and specific volume (m ³ / Kg). α is a graph showing a change in boiling point with a change in pressure reduction condition, and β is a graph showing a change in specific volume with a change in pressure reduction condition. As shown in FIG. 3, the boiling point decreases as the pressure decreases, but the specific volume increases conversely. Boiling points (α1, α2, α3, α4) and specific volumes (β1, β2, β3, β4) at four time points of -0.07 MPaG, -0.08 MPaG, -0.09 MPaG, and -0.096 MPaG Is shown in Table 1. As shown in FIG. 3 and Table 1, when the pressure is −0.07 MPaG, the boiling point (α1) is 70.1 ° C., the specific volume (β1) is 5.05 m ³ / Kg, and the pressure is −0. The boiling point (α2) at 08 MPaG is 61.5 ° C. and the specific volume (β2) is 7.2 m ³ / Kg, but when the pressure drops from −0.08 MPaG, the temperature gradient becomes steep and the boiling point suddenly increases. When the pressure decreases to -0.096 MPaG, the boiling point (α4) is 33.9 ° C. and the specific volume (β4) is 26.7 m ³ / Kg. The specific volume increases rapidly from around -0.096 MPaG.

  Considering only thermal efficiency, the lower the pressure, the more advantageous. However, when the specific volume is increased, even if the steam has the same weight, the ejector pump 4 having a larger capacity is required as the specific volume is increased. It is necessary to increase the diameter of the pipe 17 or the like. This is because when the amount of steam generated from the sludge S exceeds the amount of steam sucked by the ejector pump 4, the pressure in the decompression processing tank 1 increases, and the target processing capacity cannot be obtained. Therefore, as the reduced pressure state, a range of −0.07 MPaG to −0.096 MPaG having a boiling point of about 70 ° C. or less and a small increase in specific volume is preferable, and a range of −0.08 MPaG to −0.096 MPaG is more preferable.

  Next, as shown in step C, the sludge S in the decompression tank 1 is indirectly heated. As a method of indirect heating, a steam boiler is used as the heating source 9, and the heated steam is supplied from the heating source 9 to the heating shaft 5 through the supply pipe 10, and the supply pipe 10 a is branched in the middle. The heating steam is supplied to the heating jacket 8 as well. The heating steam supplied to the heating shaft 5 joins the discharge pipe 11 from the heating shaft 5 via the discharge pipe 11 and the heating steam supplied to the heating jacket 8 joins the discharge pipe 11 via the discharge pipe 11a. It returns to the steam boiler of 9 and is heated again.

  In addition, as shown in step D, the heating efficiency of the sludge S is improved by stirring the sludge S in the decompression tank 1. As a stirring method, the motor 7 is driven and the heating shaft 5 is rotated, whereby the stirring blades 6 projecting from the outer peripheral surface of the heating shaft 5 at regular intervals are rotated and the sludge S is stirred.

  Since the sludge S in the reduced pressure treatment tank 1 is indirectly heated while being kept under reduced pressure and having a reduced boiling point, the liquid component in the sludge S is transferred from the reduced pressure treatment tank 1 to steam as shown in Step E. It is taken out outside. Specifically, the liquid component evaporated as vapor from the sludge S in the decompression processing tank 1 is taken out from the decompression processing tank 1 through the steam pipe 17, and is transferred from the condensation pipe 19 to the condensation tank 2 through the reducer 18. Supplied.

  As shown in Step F, the steam supplied to the condensing tank 2 is condensed in the condensing tank 2, liquefied again, and stored in the condensing tank 2. That is, the vapor supplied to the condensing tank 2 is liquefied again as the temperature decreases in the condensing tank 2.

  In order to promote the liquefaction of the vapor due to condensation, as shown in Step G, a cooling liquid is injected onto the vapor taken out from the decompression processing tank 1. That is, the liquid material 16 stored in the condensing tank 2 by driving the shower pump 22 installed in the condensing tank 2 is supplied as a cooling liquid into the reducer 18 through the shower pipe 23, and the liquid material is directed toward the condensing pipe 19. By injecting 16, the vapor that has entered the reducer 18 can be rapidly liquefied.

  In addition, as a cooling means for effectively using the temperature of the liquid material 16 in the condensing tank 2 and maintaining the temperature of the liquid material 16 appropriately, a step is performed before the sludge S as a raw material is put into the decompression processing tank 1. Preheating shown in H is good. That is, the circulation pump 25 installed at the bottom of the condensing tank 2 is driven to circulate the liquid material 16 whose temperature has been improved by condensation of the vapor stored in the condensing tank 2 and taken out from the decompression tank 1. By supplying the preheating device 27 via the piping 26 and preheating the sludge S and then putting it into the vacuum treatment tank 1, the liquid component from the sludge S can be efficiently taken out by evaporation.

  The liquid material 16 supplied to the preheating device 27 and releasing the heat is cooled and returned to the condensing tank 2 as shown in Step I. That is, the liquid material 16 is supplied from the preheating device 27 to the cooling device 30 such as a cooling tower via the cooling pipe 29, cooled by an appropriate means such as shower ring, and circulated to the condensing tank 2 via the return pipe 31.

  These operations are continued for a predetermined time until the liquid component is taken out from the sludge S put into the decompression tank 1 and becomes completely dry. When the sludge S becomes completely dry, as shown in Step J. In addition, the batch processing is finished per one time by taking out from the product discharge port 14 of the decompression processing tank 1. Thereafter, this operation is repeated to dry the sludge S.

  FIG. 4 shows the relationship between pressure, temperature and time when the same moisture content as described above is applied to dry sludge S consisting of 1500 kg of rolled sludge having a moisture content of 13.7% by weight (less than 1% moisture content). In the graph, time is plotted on the horizontal axis, pressure (MPaG) is plotted on the right vertical axis, and temperature (° C.) is plotted on the left vertical axis. X1, Y1, and Z1 are graphs showing the pressure (MPaG) of the decompression processing tank 1, respectively, and X2, Y2, and Z2 are graphs showing the temperature (° C.) of the decompression processing tank 1, respectively. Further, P1, P2, and P3 represent points at which drying ends (processing time), respectively. In addition, by supplying the heated steam to the heating jacket 8 and the heating shaft 5, the temperature in the decompression tank 1 is indirectly heated so as to be about 130 ° C., and the temperature of the liquid 16 in the condensation tank 2 is set to 40 ° C. To keep below.

  According to X1 and X2, when the reduced pressure treatment tank 1 is kept at -0.074 MPaG as a reduced pressure state, the boiling point is lowered to 80 ° C. or less from the lapse of 30 minutes, and the drying treatment (water content 0.8 wt. %) Ended in 57 minutes. When the absolute dry state is reached, the temperature in the reduced pressure treatment tank 1 starts to rise. Moreover, according to Y1, Y2, when the reduced pressure treatment tank 1 is kept at -0.080 MPaG as a reduced pressure state, the boiling point is lowered to 70 ° C. or lower from the lapse of 30 minutes, and finally to 70.1 ° C., As shown in P2, the drying process was completed in 47 minutes (water content: 0.8% by weight). Furthermore, according to Z1 and Z2, when the reduced pressure treatment tank 1 is kept at -0.091 MPaG as a reduced pressure state, the boiling point decreases from about 30 minutes to nearly 60 ° C., and the drying process is completed in 41 minutes as shown in P3. (Water content 0.8% by weight). Comparing P1, P2, and P3, which are drying end times, P2 is 18% shorter than P1, and P3 is 13% lower than P2, and 28% lower than P1. Time has been shortened.

  Therefore, as described above, the range of the decompression condition is preferably -0.07 MPaG to -0.096 MPaG, more preferably -0.08 MPaG to -0.096 MPaG. In this embodiment, in step G, the cooling liquid is sprayed onto the steam to accelerate the condensation of the steam. However, even if the cooling liquid spray is omitted, the drying processing time increases but the drying processing can be performed. And within the scope of the present invention.

  FIG. 5 is a graph showing the relationship between the pressure, temperature and time when the sludge S composed of the same 1500 Kg rolled sludge as described above is dried to a completely dry state (moisture content of less than 1%), with time on the horizontal axis. , The right vertical axis represents pressure (MPaG), and the left vertical axis represents temperature (° C.). A1, B1, and Z1 are graphs showing the pressure (MPaG) of the decompression processing tank 1, and A2, B2, and Z2 are graphs showing the temperature (° C.) of the decompression processing tank 1, respectively. Moreover, P3, P4, and P5 represent the point (processing time) of completion | finish of drying, respectively. In addition, the heating conditions of the decompression processing tank 1 and the temperature of the liquid material 16 in the condensing tank 2 are the same conditions as the drying processing method shown in FIG.

  Z1 and Z2 are the same examples as Z1 and Z2 shown in FIG. 4, and the decompression treatment tank 1 is maintained at -0.091 MPaG as a decompressed state, and in step G, the coolant is injected into the steam to condense the steam. Promoting. On the other hand, A1 and A2 are those in which the reduced pressure treatment tank 1 is kept at -0.088 MPaG as a reduced pressure state, and the step of injecting the cooling liquid in step G into the vapor is not performed. Z1, Z2 and A1, A2 both supply heated steam to both the heating jacket 8 and the heating shaft 5 as an indirect heating means of the decompression processing tank 1. In addition, B1 and B2 keep the decompression processing tank 1 at -0.088 MPaG in a decompressed state, do not perform the step of injecting the cooling liquid into the steam in Step G, and further, as an indirect heating means of the decompression processing tank 1, Only the jacket 8 was used, and the heated steam was not supplied to the heating shaft 5.

  According to Z1 and Z2, the drying process was completed in 41 minutes as shown in P3 (moisture content 0.8% by weight), but under substantially the same decompression conditions, the cooling water injection in step G was performed. A1 and A2, which were not performed, required 52 minutes for the drying treatment (water content: 0.7% by weight). Furthermore, under substantially the same decompression conditions, the cooling water is not injected in Step G, and only the heating jacket 8 is used as the indirect heating means of the decompression treatment tank 1, and the heated steam is applied to the heating shaft 5. In B1 and B2, which did not supply, 102 minutes were required for the drying treatment (water content: 0.9% by weight). Comparing P3, P4, and P5, which are drying end times, P3 is 61 minutes (60%) shorter than P5, and P4 is 50 minutes (49%) dry compared to P5. Time has been shortened.

  Therefore, as described above, it is shown that the injection of the cooling water in Step G and the supply of the heated steam to the heating shaft 5 together with the heating jacket 8 in Step C are effective, and the cooling liquid in Step G is effective. Even if there is no injection or supply of heated steam to the heating shaft 5, it is possible to dry various sludges to an absolutely dry state as long as the pressure reduction range is -0.07 MPaG to -0.096 MPaG. is there.

  According to the present invention described above, the sludge is treated under reduced pressure, and the liquid component is removed from the sludge in a vapor state by indirectly heating the sludge in a state where the boiling point of the liquid component in the sludge is lowered. By condensing the vapor and returning it to the liquid state again, the thermal efficiency is high and the drying process can be performed efficiently in a short time.

  When the liquid component in the sludge is water, it can be depressurized and evaporated at a low temperature, so that the oil content is less vaporized, and therefore the generation of exhaust gas is reduced. Even if it occurs, since it can be trapped in the condensing tank, it does not leak to the outside. Further, since the treatment is performed under reduced pressure, it is possible to treat at a temperature lower than the ignition point such as oil, and there is no fear of ignition. Since the reduced pressure treatment tank is indirectly heated in a sealed reduced pressure state, the sludge can be treated in any state and the sludge is not altered by heat.

  Most of the heat energy given to the sludge can be recovered as condensation latent heat in the condensation tank and can be reused for sludge preheating and the like. Since an ejector pump is used as the decompression means, even if steam or moisture is mixed in, no breakdown occurs and stable drying processing is possible. And since the vapor | steam taken out from the decompression processing tank is condensed and liquefied in a condensation tank, a gas volume becomes substantially zero and there is little load of an ejector pump.

  Furthermore, it is possible to reduce the pipe diameter to be used by reducing the volume by injecting the cooling liquid into the steam taken out from the decompression tank and condensing the steam on the spot by forcibly contacting the cooling liquid. While being possible, the pressure difference between the vacuum generated by condensation and the pressure difference due to the flow rate of the coolant improves the decompression capability. In addition, even when the amount of generated steam is small, the constant flow rate can be maintained, and the effect of washing away with water can solve the powder accumulation in the pipe.

S ... Sludge 1 ... Decompression treatment tank 2 ... Condensation tank 3 ... Ejector tank 4 ... Ejector pump 5 ... Heating shaft 6 ... Stirring blade 7 ... Motor 8 ... Heating jacket 9 ... Heating source 10, 10a ... Supply pipe 11, 11a ... Discharge Pipe 12, 12a ... Steam trap 13 ... Raw material inlet 14 ... Product outlet 16, 34 ... Liquid 17 ... Steam pipe 18 ... Reducer 19 ... Condensate pipe 20 ... Pressure release valve 21 ... Pressure maintenance valve 22 ... Shower pump 23 ... Shower pipes 24, 28, 38 ... Check valves 25 ... Circulation pumps 26 ... Circulation pipes 27 ... Preheating devices 29 ... Cooling pipes 30 ... Cooling devices 31 ... Return pipes 32 ... Raw material supply pipes 35 ... Drive pumps 36 ... Driving pipe 37 ... Communication pipe

In order to solve the above-mentioned problems, the present inventor supplies sludge to a decompression processing tank, and decompresses the inside of the decompression processing tank by an ejector pump connected to the decompression processing tank through a condensing tank storing a liquid material. By indirect heating in a state where the boiling point of the liquid component in the sludge is lowered, the liquid component is taken out from the reduced pressure treatment tank in a vapor state, and the liquid material stored in the condensation tank in the vapor is injected as a cooling liquid, The present invention basically provides a method for drying sludge that is supplied to a condensing tank and condensed, and the vapor is returned to a liquid state and stored in the condensing tank to remove liquid components from the sludge and dry.

In addition, connection configuration to stir the vacuum treatment vessel which is kept under reduced pressure, configuration set the liquid temperature of the liquid which is stored in the condensing tank to 40 ° C. or less, the ejector tank equipped with ejector pump condensing tank, the ejector By supplying the liquid material stored in the tank as a drive fluid to the ejector pump, a configuration for holding the decompression processing tank under reduced pressure via the condensation tank and a configuration for using water as the liquid material stored in the ejector tank are provided. .

And it is the sludge processing apparatus for implementing the above-mentioned sludge drying processing method, Comprising: The decompression processing tank which holds sludge under pressure reduction, the indirect heating apparatus of a decompression processing tank, and the condensation connected to the decompression processing tank A tank, a liquid material stored in the condensing tank, a cooling liquid injection means for injecting the liquid material in the condensing tank as a cooling liquid to a pipe connecting the decompression processing tank and the condensing tank, and a condensing tank A sludge drying apparatus comprising: an ejector tank connected to the ejector tank; an ejector pump equipped in the ejector tank; and a liquid material stored in the ejector tank and supplied to the ejector pump as a drive fluid.

Further, the providing a configuration in which the liquid material of the condensation tank is supplied to the sludge prior to put in a vacuum treatment tank equipped with a preheating means for preheating the sludge.

Claims (18)

  The sludge is supplied to the vacuum treatment tank and indirectly heated with the boiling point of the liquid component in the sludge lowered by decompressing the inside of the vacuum treatment tank with an ejector pump connected to the vacuum treatment tank via the condensation tank. The sludge is dried by removing the liquid component from the sludge by taking out the liquid component in a vapor state and then condensing the vapor, and then returning to the liquid state and storing it in the condensing tank. Processing method.   The sludge drying method according to claim 1, wherein the vacuum processing tank held under reduced pressure is stirred.   The method for drying sludge according to claim 1 or 2, wherein the liquid component taken out in a vapor state from the decompression treatment tank is liquefied by injecting a cooling liquid and stored in the condensation tank.   The sludge drying treatment method according to claim 1, 2 or 3, wherein the liquid component taken out from the reduced pressure treatment tank in a vapor state is supplied to a condensation tank set at a liquid temperature of 40 ° C or less to be liquefied and stored.   An ejector tank equipped with an ejector pump is connected to a condensing tank, and a liquid material stored in the ejector tank is supplied as a drive fluid to the ejector pump, whereby the decompression tank is held under reduced pressure through the condensing tank. , 2, 3 or 4. Sludge drying method.   6. The method for drying sludge according to claim 5, wherein water is used as the liquid material stored in the ejector tank.   The method for drying treatment of sludge according to claim 1, 2, 3, 4, 5 or 6, wherein the vacuum treatment tank is maintained under a reduced pressure of -0.07 MPaG to -0.096 MPaG.   The method for drying sludge according to claim 1, 2, 3, 4, 5, 6 or 7, wherein water is used as the liquid material stored in the condensing tank.   The method for drying sludge according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein the processed product after the liquid component is removed from the sludge is discharged from the reduced pressure treatment tank.   The sludge is rolled sludge, sludge, oil / water mixture or volatile organic compound (VOC) contaminated soil, and the liquid component contained in the sludge is water, oil or volatile organic compound (VOC). , 4, 5, 6, 7, 8, or 9 The sludge drying method. A sludge treatment apparatus for carrying out the sludge drying treatment method according to any one of claims 1 to 10,
A vacuum treatment tank that holds sludge under reduced pressure, an indirect heating device for the vacuum treatment tank, a condensation tank connected to the vacuum treatment tank, a liquid material stored in the condensation tank, an ejector tank connected to the condensation tank, A sludge drying apparatus comprising: an ejector pump equipped in an ejector tank; and a liquid material stored in the ejector tank and supplied to the ejector pump as a driving fluid.   12. The sludge drying apparatus according to claim 11, wherein the reduced pressure treatment tank is equipped with a sludge inlet and a discharge outlet for discharging a processed product that has been dried by removing a liquid component from the sludge.   The sludge drying treatment apparatus according to claim 11 or 12, wherein a heating jacket is provided on the outer peripheral surface of the decompression treatment tank as the indirect heating device.   The sludge drying treatment apparatus according to claim 11, 12 or 13, wherein a hollow heating shaft is rotatably provided in the vacuum treatment tank as the indirect heating device.   15. The sludge drying apparatus according to claim 14, wherein a plurality of stirring blades are rotatably provided on the outer peripheral surface of the heating shaft at regular intervals.   The sludge drying apparatus according to claim 11, 12, 13, 14, or 15, wherein heated steam is supplied to the indirect heating apparatus.   The cooling liquid injection means which injects the liquid substance in a condensation tank as a cooling liquid toward the condensation tank to the piping which connects a decompression processing tank and a condensation tank, It equips with 11, 12, 13, 14, 15 or 16. Sludge drying treatment equipment.   18. A sludge drying apparatus according to claim 11, further comprising preheating means for preheating the sludge by supplying the liquid in the condensing tank to the sludge before being charged into the decompression tank. .

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