JPH0780000B2 - Sludge oiling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention thermochemically reacts organic sludge such as surplus sludge generated from a microorganism treatment apparatus such as an activated sludge apparatus under high temperature and high pressure conditions. The present invention relates to a sludge oilification device which obtains a combustible liquid and uses the combustible liquid as a heat energy source or an electric energy source for the thermochemical reaction.

[Prior Art] A sludge oilification technique has been proposed as one of the methods for treating organic sludge such as excess sludge generated from various microbial treatment devices.

That is, it is a technique for obtaining fuel oil from biomass by thermochemically reacting organic sludge under high temperature and high pressure conditions.

Conventionally, a device for obtaining asphalt and fuel oil from sewage sludge has been proposed as this type of technology (EPA Project Summary EPA
-600 / S2-81-242 Dec, 1981).

This apparatus is based on the flow shown in FIG. 3, in which the organic sludge A is dehydrated to some extent by a centrifuge B, the dehydrated sludge C is pressurized by a high pressure slurry pump D, and first, a reactor F described later is used. The preheated dehydrated sludge C is supplied to the reactor F by preheating with the high temperature mixture slurry G immediately after the reaction by the preheater E as a heat source. The reactor F is for reacting biomass under high temperature and high pressure conditions to convert it into asphalt and fuel oil.
The reaction is carried out at a temperature of 250 ° C. to 350 ° C. and a pressure equal to or higher than the steam pressure at that temperature. The mixture slurry G of the solid matter and fuel oil obtained by such a reaction is circulated to the above-mentioned preheater E under the condition of being pressurized and indirectly heat-exchanged there. It is supplied to and released under atmospheric pressure. In the gas-liquid separator H, the mixture slurry G
Is released under atmospheric pressure, the mixture slurry G boils because of its high temperature, and some water and fuel oil evaporate. Next, the steam is cooled by the cooler I and liquefied, the liquid is processed by the centrifugal separator J, and the waste water K and the fuel oil L are mechanically separated by specific gravity. On the other hand, the mixture slurry G remaining without being evaporated in the gas-liquid separator H is processed by the centrifugal separator M, and separated into the waste water N and the solid matter O. Next, while supplying the solid O to the extractor P, an organic solvent Q recovered from a distiller S and an evaporator V described later is added,
Here, the asphalt component in the solid O is extracted, and the extract R is supplied to the distiller S to recover the organic solvent Q and obtain the asphalt T. On the other hand, the residue U of the extractor P is supplied to the evaporator V to collect the organic solvent adhering to the residue U and obtain the reaction residue W.

The flow of the proposed method for obtaining asphalt and fuel oil is roughly as described above, and the reaction residue W is used as a heat source in the reactor F.

The obtained asphalt is used for its original purpose as asphalt.

[Problems to be Solved by the Invention] In the conventionally proposed sludge oiling apparatus shown in FIG. 3, the combustible liquid contained in the reactant slurry G obtained from the reactor F is relatively low. It is easy to vaporize at temperature,
Further, it is considered that only what is called an oily substance, which is liquefied next and can be separated by a difference in specific gravity, exists, so that the oily substance in the liquid liquefied in the cooler I is separated by the centrifugal separator J in specific gravity. The separated wastewater K is removed from the system. Furthermore, the asphalt ingredients produced are
It is considered that the solid matter in the reaction product slurry G that has not evaporated in the gas-liquid separator H is attached to the solid matter, and the centrifuge M collects the asphalt component together with the solid matter, and similarly the wastewater N is used as a system. Excluded outside. However, according to the experiments conducted by the present inventors, it is difficult to vaporize the reactant slurry G at low temperature, unlike the asphalt component, it is easily dissolved in water, and a flammable liquid that can be sufficiently used as a fuel is present. It was found that a large amount of flammable liquid exists, and even if it is vaporized, it is difficult to separate the specific gravity after liquefaction. For example, the mixed raw sludge discharged from the sewage treatment plant of the standard activated sludge method is dehydrated to some extent, and 5% by weight of sodium carbonate per dry solid is added as an alkaline component to the sludge.
In the case of the closed reaction for an hour, after the reaction, the reaction product was cooled to room temperature, collected in a separating funnel and allowed to stand for one day and night, but a small amount of oily substance floated on the surface, but the remaining reaction When methylene chloride is added to the product as an organic solvent and the remaining flammable liquid is extracted, the above-mentioned floating oily substance is about 17% of the total flammable liquid, and other about 83% of the flammable liquid is It has been confirmed by experiments that it exists in the reaction solution without floating. Therefore, in the conventional flow as shown in FIG.
In addition, the combustible liquid which is easily dissolved in water cannot be separated by the centrifugal separator M, is transferred to the wastewater N and is discharged out of the system, and even if it is vaporized. The combustible liquid that is difficult to separate after liquefaction by specific gravity cannot be separated by the centrifuge J, is transferred to the wastewater K, and is discharged to the outside of the system. Furthermore, even if it is an oily substance that is easily separated from water by specific gravity, when it is present in water in an emulsified state, it cannot be separated by the centrifuge J, and these are also in an emulsified state. Part of the oily substance will also be transferred to the wastewater K and discharged.

Thus, the main purpose of the conventionally proposed flow is to produce asphalt from organic sludge, and it is considered to be a secondary purpose to obtain fuel oil, and the wastewater K or N It is completely overlooked that there is a large amount of combustible liquid that can be recovered as fuel.

Moreover, in the conventional flow shown in FIG.
Although only the reaction residue W is applied as the heat source of the above, even if it is sufficiently dehydrated until it self-burns, it is completely insufficient in terms of heat balance, and from the viewpoint of the treatment of organic sludge, It is not profitable. Further, even if the produced asphalt T and the fuel oil L are recovered as a heat source, the heat balance is still insufficient. That is, in order to economically treat the organic sludge by the sludge oilification technology, it is essential that the combustible liquid existing in the wastewater K and N described above is recovered and actively used as a heat source. Is. Moreover, in the conventional flow, since the mixture slurry G is boiled in the gas-liquid separator H, extra latent heat of vaporization is consumed here, and the vapor generated from the gas-liquid separator H is consumed in the cooler I. When cooling and liquefying, the heat released by liquefaction is not recovered, and the conventional flow has various drawbacks regarding heat recovery. Further, since the slurry-like reaction product generated in the reactor F is used as it is as the heat source of the preheater E, there is a drawback that the structure of the preheater E is restricted and it is difficult to manufacture.

The present invention has been made in view of the above-mentioned points, and a purpose thereof is to obtain a flammable substance, particularly a flammable liquid, from a reaction product obtained by reacting organic sludge under conditions of high temperature and high pressure. It is an object of the present invention to provide a sludge oiling apparatus that recovers as much as possible, reuses it as an energy source, and efficiently uses generated heat energy to most economically treat organic sludge.

[Means for Solving the Problems] The present invention relates to a dehydrator for dehydrating organic sludge in advance,
Preheater, reactor, and press-fitting device for press-fitting the dehydrated sludge in series to the cooler described later, and a preheater that indirectly preheats the dehydrated sludge that is press-fitted from the press-fitting device by the heating medium heated by the cooler in the subsequent stage. The dewatered sludge preheated by the preheater is indirectly heated by the heat medium at a temperature of 250 ° C or higher, and
Reactor for reacting at a pressure equal to or higher than the steam pressure at the temperature, the reaction product reacted in the reactor is indirectly cooled by a heat medium, and the heat medium heated by cooling the reaction product is preheated. A cooler that serves as a heat source for the reactor, an atmosphere opening device that releases the reaction product cooled by the cooler to atmospheric pressure, a recovery device that recovers the flammable liquid in the reaction product that is released from the atmosphere opening device, and a recovery device The present invention relates to a sludge oiling device, which comprises a heating furnace that burns a combustible liquid to indirectly heat a heating medium and uses the heating heating medium as a heat source of the reactor.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings together with their operation.

FIG. 1 is an explanatory view showing the flow of the present invention. First, the organic sludge 1 is first dehydrated by a dehydrator 2 such as a centrifugal separator or a belt press type dehydrator, and the dehydrated sludge 3 is preheated by a press-in device 4. Supply to the container 5. If the organic sludge contains a large amount of water, a large amount of heat is consumed in the thermochemical reaction described later, so it is desirable that the water content in the dehydrator 2 be 80% or less. Further, in the thermochemical reaction described below, the reaction proceeds more efficiently when an alkaline component is allowed to coexist in the organic sludge, so that sodium carbonate, potassium carbonate, sodium formate, potassium formate, potassium hydroxide, It is preferable to add an alkaline component such as sodium hydroxide or lime. As the press-fitting device 4 described above, for example, a high-pressure slurry pump or the like can be used.

The preheater 5 indirectly preheats the dehydrated sludge 3 using a heat medium 8 to which heat is given by a cooler 7 described later, and causes the dehydrated sludge 3 to flow inside the scraped surface heat exchanger, Heat is given from the outside by the heat medium 8 or, by using a so-called multi-tube heat exchanger or the like, the dehydrated sludge 3 is made to flow inside the pipe and heat is given by the heat medium 8 from outside the pipe. Etc. can be used.

The dehydrated sludge 3 preheated by the preheater 5 is then fed to the reactor 6
, Where the organic sludge 3 is thermochemically reacted under high temperature and high pressure conditions. The reactor 6 uses the same scraping surface heat exchanger as the preheater 5 described above or a multi-tube heat exchanger, and indirectly by the heat medium 8 heated by the first heat exchanger 24 described later. Dehydrated sludge 3 is heated, usually 25
The reaction is performed at a temperature of 0 ° C. to 350 ° C. and a pressure corresponding to the steam pressure at the temperature, or at a pressure higher than that. The dewatered sludge 3 is still in the form of a slurry having poor fluidity in the preheater 5 and before and during the reaction by the reactor 6, and therefore, it has a scraped surface rather than a multitubular heat exchanger. It is desirable to use a rotary heat exchanger. Further, although the preheater 5 and the reactor 6 are separately installed in the drawing, the preheater 5 and the reactor 6 may be integrated, and the first half of the inflow side of the dehydrated sludge serves as the preheating part and the second half of the outflow side. It is also possible for the part to be the reaction part.

When the organic sludge is treated at high temperature and high pressure in this way, the biomass is thermochemically modified to produce various combustible liquids and at the same time, the fluidity is changed to a very good one. Next, the mixture slurry 9 of the solid matter, the flammable liquid, and the water that has passed through the reactor 6 is supplied to the cooler 7 in a pressurized state and indirectly cooled by the heat medium 8. By using the heat medium 8 to which heat has been given by cooling in this way as the heat source of the preheater 5, the heat given by the reactor 6 is effectively recovered. As the cooler 7, a thin-film flow-down heat exchanger, a full-tube heat exchanger, a scraped surface heat exchanger, or the like can be used. However, since the mixture slurry 9 has extremely good fluidity, it has high thermal efficiency. It is desirable to use the best thin film flow down heat exchangers.

The mixture slurry 9 thus cooled is then supplied to the atmosphere opening device 10 to change the state under pressure to the state under normal pressure.

As the atmosphere release device 10, for example, a receiving tank that receives the mixture slurry 9 from the cooler 7 and a red down valve provided below the receiving tank can be used.

Mixture slurry 9 supplied by the atmosphere opening device 10
Is then fed to the flotation separation tank 11 to selectively recover the oily substance 12 which is a part of the flammable liquid floating in water, from the flammable liquid in the mixture slurry 9. When a part of the flammable liquid that floats on water adheres to the solid matter in the liquid, it may be stirred before being supplied to the floating separation tank 11. As the flotation / separation tank 11, it is possible to use one in which the mixture slurry 9 is simply retained in the tank for a certain time and the floating oily substance 12 is scraped off by a skimmer or the like, or an oil separator having a so-called simple structure or the like. . The mixture slurry 9 from which the oily substance 12 has been removed by the flotation tank 11 and then the extraction tank
The mixture is sent to 13, and the solvent 14 recovered by the solvent recovery device 20 to be described later is added and sufficiently stirred to extract the flammable liquid in the mixture slurry 9. The extraction tank 13 may be of any type as long as the mixture slurry 9 and the solvent 14 can be brought into necessary and sufficient contact with each other.
A simple one in which the mixture of and is stirred with a stirrer in the tank may be used.

The solvent 14 to be used is preferably one that can extract all the flammable liquids in the mixture slurry 9 as much as possible and is easy to evaporate and recover. Usually, benzene, toluene,
Acetone, methylene chloride, etc. are used.

The mixture 15 obtained batchwise or continuously from the extraction tank 13 is then fed to a three-phase separator 16 where wastewater
Separated into 17, solid 18 and extract 19. The three-phase separator
16 is a so-called centrifuge, which has different specific gravities
It is possible to use a publicly known one that separates 17, solid 18 and extract 19 by centrifugal action. The extract 19 obtained by the three-phase separator 16 is then fed to the solvent recovery device 20 and indirectly heated by the heat medium 8 heated by the second heat exchanger 25 described later to remove the solvent 14. Evaporate and collect the flammable liquid 21, which is the evaporation residue. In the drawing, the solvent 14 recovered from the solvent recovery device 20 is directly extracted from the extraction tank.
Although it is being supplied to the solvent 13, in reality, the gaseous solvent obtained from the solvent recovery device 20 is cooled and liquefied by a cooler (not shown) and recovered as a liquid solvent 14.

In the present embodiment, the floating separation tank 11, the extraction tank 13, the three-phase separator 16, the solvent recovery device 20, etc. described above correspond to a device for recovering the flammable liquid in the reaction product, but are particularly limited to a combination thereof. In short, any substance may be used as long as it can effectively recover the combustible liquid from the reaction product.

Reference numeral 22 denotes a heating furnace, which uses the flammable liquid 21 recovered from the solvent recovery device 20 or the oily substance 12 recovered from the floating separation tank 11 as a fuel, and hot air obtained by burning these fuels. 23 is supplied to the first heat exchanger 24 to heat the heat medium 8 used in the reactor 6, and then the hot air 23 is continuously supplied to the second heat exchanger 25 to supply the solvent recovery device 20. The heating medium 8 used in (1) is heated. 26
Represents exhaust gas, 27 represents combustion air, and 28 represents combustion ash.

In the flow shown in FIG. 1, the mixture slurry 9 obtained from the atmosphere opening device 10 is supplied to the flotation separation tank 11,
Although the oily substance 12 is selectively recovered in advance, this step is omitted, and the mixture slurry 9 obtained from the atmosphere opening device 10 is directly supplied to the extraction tank 13 to extract all the existing combustible liquid. It doesn't matter. It should be noted that if the recovery step of the oily substance 12 is omitted in this way, the amount of the solvent 14 used increases slightly, and the flammable liquid 21 obtained from the solvent recovery device 20 also contains the oily substance 12 described above. Become.

FIG. 2 is an explanatory view showing the flow of another embodiment of the present invention, and the process up to the step of recovering the oily substance 12 by the floating separation tank 11 is exactly the same as that of FIG. The mixture slurry 9 from which the oily substance 12 has been removed by the floating separation tank 11 is then separated into a solid-liquid separator 29 such as a centrifugal separator.
To remove solids 18 in the mixture slurry 9.
The mixed solution 30 from which solids have been removed is then supplied to the extraction device 31, and the solvent 14 recovered by the solvent recovery device 20 is added to the mixed solution.
Extract the flammable liquid in 30. As the extraction device 31 used in the flow shown in FIG. 2, since the solids 18 are removed in advance, it is more efficient to use the one in which the solvent 14 and the mixed solution 30 are brought into countercurrent contact with each other. When using a solvent having a larger specific gravity, as shown in the figure, the solvent 14 is caused to flow downward from above, and the mixed solution 30 is caused to flow upward from below, and when a solvent having a smaller specific gravity than the mixed solution 30 is used. It is advisable to make the upper and lower sides opposite to each other and bring them into countercurrent contact. The extract 19 thus obtained is supplied to the solvent recovery apparatus 20, and the other steps are the same as in FIG. In the flow shown in FIG. 2, since some combustible liquid adheres to the solid 18 obtained by the solid-liquid separator 29, it is preferable to use the solid 18 as fuel for the heating furnace 22. Further, as in the case of FIG. 1, the floating separation tank 11 can be omitted.

In the present embodiment, the floating separation tank 11, the solid-liquid separator 29, the extraction device 31, the solvent recovery device 20, etc. correspond to the device for recovering the flammable liquid in the reaction product, but are not particularly limited to the combination thereof. In short, any material can be used as long as it can effectively recover the flammable liquid from the reaction product.

[Effects of the Invention] As described above, in the present invention, a slurry of a mixture of a solid, a flammable liquid, and water, which is obtained by thermochemically reacting organic sludge under high temperature and high pressure conditions, or a slurry of the mixture. Since the organic solvent is added to the mixed solution in which the solid matter is removed in advance and all the flammable liquids contained in the mixed slurry or mixed solution are extracted, it is difficult to vaporize in the mixed slurry or mixed solution, and the water Even if a large amount of flammable liquid that is easily dissolved is contained, it can be recovered as much as possible, and by using the recovered combustible liquid as a heat energy source or an electric energy source, it is economical. Can treat organic sludge.

Further, in the present invention, the cooler 7 is installed in the latter stage of the reactor 6, the mixture slurry 9 obtained from the reactor 6 is indirectly cooled by the heat medium 8 without boiling, and heat is applied by the cooling. Since the generated heat medium 8 is used as the heat source of the preheater 5 used in the preceding stage of the reactor 6, the heat energy cost is surely reduced by the amount of the latent heat of vaporization consumed when boiling the mixture slurry as in the conventional flow. Further, since the heat medium to which heat is given by the cooler 7 is used as the heat source of the preheater, the heat energy cost can be reduced also in this respect. Further, unlike the conventional flow, the high temperature mixture slurry 9 obtained from the reactor 6 is not directly used in the preheater 5, so that the structure of the preheater is not particularly limited.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 are drawings showing an embodiment of the present invention, and FIG. 1 is an explanatory view showing a flow of one embodiment of the present invention. FIG. 2 is an explanatory diagram showing a flow of another embodiment of the present invention. Further, FIG. 3 shows a flow in a method for obtaining asphalt and fuel oil from conventional sewage sludge. 1 ... Organic sludge, 2 ... Dewatering device 3 ... Dewatering sludge, 4 ... Press-in device 5 ... Preheater, 6 ... Reactor 7 ... Cooler, 8 ... Heat medium 9 ... Mixture slurry , 10 …… Atmosphere opening device 11 …… Flotation separation tank, 12 …… Oily substance 13 …… Extraction tank, 14 …… Solvent 15 …… Mixture, 16 …… Three-phase separator 17 …… Waste water, 18 …… Solid Material 19 …… Extract, 20 …… Solvent recovery device 21 …… Combustible liquid, 22 …… Heating furnace 23 …… Hot air, 24 …… First heat exchanger 25 …… Second heat exchanger, 26 …… Exhaust gas 27 …… Combustion air, 28 …… Combustion ash 29 …… Solid-liquid separator, 30 …… Mixed solution 31 …… Extractor

Claims (1)

[Claims] 1. A dehydrating device for dehydrating organic sludge in advance, a press-fitting device for press-fitting the dehydrated sludge in series with a preheater, a reactor, and a cooler described later, and a dehydrating sludge press-fitted from the press-fitting device in the subsequent stage. A preheater that indirectly preheats with a heat medium heated with a cooler, and dewatered sludge preheated with a preheater is indirectly heated with a heat medium, at a temperature of 250 ° C or higher and at a pressure of steam pressure or higher at that temperature. A reactor to react, a cooler that cools the reaction product reacted in the reactor indirectly by a heat medium, and a heat medium heated by cooling the reaction product as a heat source of the preheater, a cooler An atmosphere opening device for opening the cooled reactant to atmospheric pressure,
A recovery device for recovering the flammable liquid in the reaction product released from the atmosphere opening device, the flammable liquid recovered from the recovery device is burned to indirectly heat the heat medium, and the heating heat medium of the reactor is used. A sludge oiling device comprising a heating furnace as a heat source.