JPS61213293A - Method of extracting combustible liquid - Google Patents

Abstract

PURPOSE:To obtain combustible liquid usable as a heat energy source of thermochemical reaction or an electric energy source, by extracting slurry of a mixture of a solid matter / combustible liquid / water, a thermochemical reaction product of organic sludge, with an organic solvent. CONSTITUTION:Slurry of a mixture of a solid matter / combustible liquid / water obtained by reacting thermochemically organic sludge such as excess sludge produced from a microorganism treated device is obtained. The slurry is blended with an organic solvent such as benzene, toluene, acetone, methylene chloride, etc., to extract the combustible liquid. EFFECT:Organic sludge is treated efficiently and economically.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention thermochemically reacts organic sludge such as surplus sludge generated from microbial treatment equipment such as activated sludge equipment under high temperature and high pressure conditions to produce combustible sludge. The present invention relates to a so-called sludge-to-oil technology in which a flammable liquid is obtained and the flammable liquid is used as a thermal energy source or electrical energy source for the thermochemical reaction.

<Prior Art> A sludge oil technology has been proposed as one method for treating organic sludge such as surplus sludge generated from various microbial treatment devices.

In other words, it is a technology that thermochemically reacts organic sludge under high temperature and high pressure conditions to obtain fuel oil from biomass.

Conventionally, a method of obtaining asphalt and fuel oil from sewage sludge has been proposed as this type of technology (HPA Project
Summary EPA-600/52-8l-24
2Dec, 1981).

This method is based on the flow shown in Figure 4, in which organic sludge A is dehydrated to a certain extent in centrifuge B, and sludge C
is pressurized by a high-pressure slurry feeder, and first, the high-temperature mixture slurry 〇 immediately after reacting in reactor F, which will be described later, is preheated in preheater E using the heat source, and the preheated dehydrated sludge C is supplied to reactor F. It is something. The reactor F converts biomass into asphalt and fuel oil by reacting it under high temperature and high pressure conditions, and usually converts dehydrated sludge to 250℃~
The reaction is carried out at a temperature of 350° C. and a pressure corresponding to the vapor pressure at that temperature. The slurry G, which is a mixture of solids and fuel oil obtained by such a reaction, is circulated under pressure to the preheater E described above, where heat is exchanged indirectly, and then supplied to the gas-liquid separator H. and release to atmospheric pressure. When the mixture slurry G is released to atmospheric pressure in the gas-liquid separator H, the mixture slurry 〇 boils due to the high temperature, and some water and fuel oil evaporate. Next, the vapor is cooled and liquefied by a cooler I, and the liquid is processed by a centrifuge J, and mechanically separated into waste water and fuel oil by specific gravity, while being evaporated in a gas-liquid separator H. The remaining mixture slurry G is processed by a centrifuge M, and the waste water N
and 0 solids.

Next, the solid matter 0 is supplied to the extractor P, and an organic solvent Q is recovered from the distiller S and the evaporator ■, which will be described later.
is added to extract the asphalt component in the solid matter 0, and the extract R is supplied to the distiller S to recover the organic solvent Q and obtain asphalt T. On the other hand, the residue U from the extractor P is supplied to the evaporator V to recover the organic solvent adhering to the residue U and obtain a 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.

Although the obtained asphalt is said to be used for its original purpose as asphalt, the fuel oil obtained simultaneously with the asphalt can also be used as a heat source in the reactor F.

<Problems to be solved by the invention> In the conventionally proposed sludge oiling technology shown in FIG. 4, the amount of flammable liquid contained in the reactant slurry G obtained from the reactor F is relatively low. We believe that only so-called oily substances exist, which are easily vaporized by temperature and can be separated by the difference in specific gravity after being liquefied. J separates the water by specific gravity, and the remaining waste water K is removed from the system.

Furthermore, it is believed that the produced asphalt components are attached to the solids in the reactant slurry G that did not evaporate in the gas-liquid separator H, so the asphalt components are collected together with the solids in the centrifuge M, and the same In this way, wastewater N is removed from the system. However, experiments conducted by the inventors (see Examples)
According to Reactant Slurry G, there is a large amount of flammable liquid that is difficult to vaporize at low temperatures, is easily soluble in water unlike asphalt components, and can be used as fuel, and that there is a large amount of flammable liquid that is difficult to vaporize at low temperatures. However, it was discovered that there are flammable liquids that are difficult to separate by specific gravity difference after liquefaction. Therefore, in the conventional flow shown in Figure 4, such flammable liquids that are difficult to vaporize and easily dissolve in water cannot be separated by the centrifuge M, and are transferred to the wastewater N. It will be discharged outside the system,
Further, even if it is vaporized, combustible liquid, which is difficult to separate by specific gravity after liquefaction, cannot be separated by the centrifuge J, and will be transferred to waste water and discharged outside the system.

Furthermore, although it is an oily substance that is easily separated from water by specific gravity, if it exists in an emulsified state in water, it is impossible to separate it using a centrifuge J. Oily substances will also migrate into the wastewater and be discharged.

The main purpose of the conventionally proposed flow is to produce asphalt from organic sludge, and obtaining fuel oil is considered to be a secondary purpose. The fact that there is a large amount of flammable liquid that can be recovered as waste is completely overlooked.

In addition, in the conventional flow shown in Figure 4, only the reaction residue W is used as the heat source for the reactor F, but even if it is sufficiently dehydrated until it self-combusts, it is completely insufficient in terms of heat balance to be used as fuel. Therefore, it is not profitable from the viewpoint of treating organic sludge. Furthermore, even if the produced asphalt T and fuel oil are recovered as a heat source, the heat balance is still insufficient. In other words, in order to economically treat organic sludge using sludge oil technology, it is essential to recover the flammable liquid present in the aforementioned wastewater and N and actively use it as a heat source. be.

Furthermore, in the conventional flow, the mixture slurry 〇 is boiled, which has the disadvantage that extra latent heat of vaporization has to be consumed.

The present invention has been made in view of the above points, and its purpose is to remove flammable substances, especially flammable liquids, from the reactants obtained by reacting organic sludge under high temperature and high pressure conditions. The goal is to collect the waste and reuse it as an energy source. Furthermore, it is the most economical way to treat organic sludge by efficiently using the heat energy generated.

<Means for Solving the Problems> The first aspect of the present invention is to extract water from a slurry of a mixture of solids, flammable liquid, and water obtained by reacting organic sludge under high temperature and high pressure conditions. A pre-process is performed to mechanically separate and collect some of the flammable liquid floating in the water, and then an organic solvent is added to the mixed slurry after the pre-process or to the mixed slurry that has not undergone the pre-process and dissolved in water. The second invention of the present invention involves reacting organic sludge under high temperature and high pressure conditions. From the slurry of the mixture of solids, flammable liquid, and water obtained by this process, if necessary, a pre-process is performed to mechanically separate and recover some of the flammable liquid that floats on water, and then the pre-process is performed. Solids are first separated from the subsequent mixture slurry or a mixture slurry that has not undergone the previous step, and then an organic solvent is added to the mixture slurry of flammable liquid and water obtained by the separation, and the solids are dissolved in water. This method extracts and recovers all forms of flammable liquids, such as oily substances, emulsified substances, etc., as much as possible.

Effect〉 The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is an explanatory diagram showing the flow of the first invention of the present invention, in which organic sludge 1 is first dehydrated using a dewatering device, such as a belt press type dehydrator, and the dehydrated sludge 3 is
is supplied to the preheater 5 by the press-fitting device 4. Note that if the organic sludge contains too much water, a large amount of heat will be consumed in the thermochemical reaction described below, so it is desirable to dehydrate the organic sludge to a water content of 80% or less in the dehydrator 2.

Furthermore, in the thermochemical reaction described below, the reaction proceeds more efficiently when an alkali component is present in the organic sludge, so it is preferable to add an alkali component such as sodium carbonate or lime to the organic sludge in advance. The aforementioned press-fitting device 4
For example, a high-pressure slurry pump or one that flows the dehydrated sludge 3 into a cylinder and pushes out the dehydrated sludge 3 with a piston driven by hydraulic pressure or the like is used. Further, the preheater 5 indirectly preheats the dehydrated sludge 3 using a heat medium 8 given heat by a cooler 7, which will be described later, and allows the dehydrated sludge 3 to flow through the inside of the surface heat exchanger. Heat may be applied from the outside using the heat medium 8, or dehydrated sludge 3 may be passed through the inside of the tube using a so-called shell-and-tube heat exchanger, and heat may be applied from the outside of the tube using the heat medium 8. Good to use.

The dehydrated sludge 3 preheated by the preheater 5 is then supplied 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 surface heat exchanger or multi-tube heat exchanger as the preheater 5 described above, and indirectly heats the dehydrated sludge 3 by the heat medium 8 heated by the first heat exchanger 24 described later. It heats the temperature, usually 250℃
The reaction is carried out at a temperature of ~350°C and a pressure corresponding to the vapor pressure at that temperature. In the drawing, the preheater 5 and the reactor 6 are installed separately, but the preheater 5 and the reactor 6 may be integrated.The first half of the dehydrated sludge inflow side is the preheating section, and the second half of the outflow side is the preheating section. It can also be used as a reaction section.

When organic sludge is treated at high temperature and pressure in this way, the biomass is thermochemically transformed and various flammable liquids are produced.

Next, the slurry 9 of the mixture of solids, combustible liquid, and water that has passed through the reactor 6 is supplied in a pressurized state to the cooler 7 and cooled indirectly by the heat medium 8 . Note that by using the heat medium 8 that has been given heat by cooling as a heat source for the preheater 5, the heat given by the reactor 6 can be effectively recovered. Note that as the cooler 7, a thin film falling type heat exchanger, a full tube heat exchanger, a drawn surface type heat exchanger, etc. can be used.

The mixture slurry 9 cooled in this manner is released to atmospheric pressure, and is supplied to the stirring tank 1o to sufficiently stir the mixture slurry 9. This operation is necessary to selectively recover some of the flammable liquid that floats in the flotation tank 11, which will be described later. It is something.

The mixture slurry 9 subjected to such agitation treatment is then fed to the flotation separation tank 11, and the oily substance 12, which is a part of the flammable liquid that floats on water, is selectively removed from the flammable liquid in the mixture slurry 9. to be collected.

As the flotation separation tank 11, a tank in which the mixture slurry 9 is simply retained for a certain period of time and the floating oily substance 12 is scraped off with a skimmer or the like, or a so-called oil separator with a simple structure can be used. Flotation separation tank 1
The mixture slurry 9 from which the oily substance 12 has been removed in step 1 is then sent to the extraction tank 13, and the solvent 14 recovered by a solvent recovery device 20 (to be described later) is added thereto and sufficiently stirred to form the mixture slurry 9.
Extract the flammable liquid inside. The extraction tank 13 may be of any type as long as it can bring the mixture slurry 9 and the solvent 14 into necessary and sufficient contact, and the mixture of the mixture slurry 9 and the solvent 14 is stirred in the tank using a stirrer. It doesn't matter if it's something simple.

The solvent 14 used is preferably one that can extract as much of the flammable liquid as possible in the mixture slurry 9 and easily recover it by evaporation, and 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 it is separated into waste water 17, solids 18 and extract 19. The three-phase separator 16 is a so-called centrifugal separator, which separates waste water 17, solid matter 18, and extract 19 having different specific gravity by centrifugal action, and a known one can be used.

The extract 19 obtained by the three-phase separator 16 is then sent to a solvent recovery device 20, where it is indirectly heated with a heat medium 8 heated by a second heat exchanger 25, which will be described later, to recover the solvent 1.
4 is evaporated, and the evaporation residue, flammable liquid 21, is recovered. In addition, in the drawing, the solvent 1 recovered from the solvent recovery device 20 is
4 is directly supplied to the extraction tank 13, but in reality, the gaseous solvent obtained from the solvent recovery device 2° is cooled and liquefied in a cooler (not shown) and recovered as a liquid solvent 14.

22 is a heating furnace which uses as fuel the flammable liquid 21 recovered from the solvent recovery device 2o or the oily substance 12 recovered from the flotation tank 11, and hot air 23 obtained by burning these fuels. 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 subsequently supplied to the second heat exchanger 25 to heat the heat medium 8 used in the solvent recovery device 20. Heat the medium 8. Note that 26 is exhaust gas, 27 is combustion air, and 2
8 indicates combustion ash.

In addition, in the flow shown in FIG. 1, the mixture slurry 9 obtained from the cooler 7 is passed through the stirring tank 1o to the flotation separation tank 1.
1, and the oily substance 12 is selectively recovered in advance, but this step is omitted and the mixed substance slurry 9 obtained from the cooler 7 is directly supplied to the extraction tank 13 to remove the existing flammable liquid. There is no problem in extracting all of them. Note that if the oily substance 12 recovery step is omitted in this way, the amount of solvent 14 used will increase slightly, and the flammable liquid 21 obtained from the solvent recovery device 20 will also contain the aforementioned oily substance 12.

FIG. 2 is an explanatory diagram showing the flow of the second invention of the present invention, and since the steps up to the step of recovering the oily substance 12 by the flotation separation tank 11 are completely the same as the first invention, the explanation will be omitted. The mixture slurry 9 from which the oily substances 12 have been removed by the flotation tank 11 is then passed through a solid-liquid separator 2 such as a centrifuge.
9, where the solid matter 18 in the mixture slurry 9 is removed, and the mixed solution 30 from which the solid matter has been removed is subsequently sent to an extraction device 31.
The solvent 14 collected by the solvent recovery device 20 is added to extract the flammable liquid in the mixed solution 30.

Since the solid matter 18 is removed in advance as the extraction device 31 used in the second invention, it is more efficient to use one that brings the solvent 14 and the mixed solution 30 into countercurrent contact. When using, as shown in the figure, the solvent 14 is flowed downward from above, and the mixed solution 30 is flowed upward from below, and when using a solvent with a smaller specific gravity than the mixed solution 30, the vertical direction is reversed. , it is preferable to carry out countercurrent contact in both cases, and the extract 19 obtained in this way is supplied to the solvent recovery device 20, and since the other aspects are the same as in the first invention, the explanation will be omitted.

Note that in the flow in the second invention, since some flammable liquid adheres to the solid material 18 obtained in the solid-liquid separator 29, it is preferable that the solid material 18 is also used as fuel for the heating furnace 22. Further, as in the first invention, the stirring tank 10 and flotation separation tank 11 can be omitted.

Effect> As explained above, in the present invention, solids are removed from a slurry of a mixture of solids, a flammable liquid, and water obtained by thermochemically reacting organic sludge under high temperature and high pressure conditions, or from the slurry of the mixture. An organic solvent is added to the mixed solution that has been removed in advance to extract all flammable liquids contained in the mixture slurry or mixed solution. Even if a large amount of flammable liquid is contained, it can be recovered as much as possible, and the recovered flammable liquid can be used as a source of thermal energy or electrical energy to economically process organic sludge. can do.

Further, in the present invention, a cooler 7 is installed after the reactor 6, and the mixture slurry 9 obtained from the reactor 6 is indirectly cooled by the heating medium 8 without boiling, and heat is given by the cooling. Since the heat medium 8 is used as a heat source for the preheater 5 used at the front stage of the reactor 6, the thermal energy cost can be surely reduced by the amount of latent heat of vaporization consumed when boiling the mixture slurry as in the conventional flow. I can do it.

Examples will be shown below to make the effects of the present invention more clear.

<Example-1> Mixed raw sludge discharged from a sewage treatment plant using the standard activated sludge method was selected as the organic sludge, and after adding a polymer flocculant to it, it was dehydrated using a belt press and used in the following experiment. Using.

That is, 6% by weight of soda carbonate was added to the dehydrated sludge as an alkaline component based on the dry solid matter, and 200% of the sludge was
Fill an autoclave with an internal capacity of 300ml, and
The reaction was carried out in a sealed manner for 1 hour at a reaction temperature of 0°C.

After the reaction, the reaction product was cooled to room temperature, collected in a separatory funnel, and allowed to stand overnight. After standing still, the oily substance (Oil A) floating on the surface of the reactant is separated in advance, and methylene chloride is added to the remaining reactant to remove the remaining flammable liquid (Oil A).
Oil B) was extracted. Table 1 shows the properties of the dehydrated sludge used in the experiment, and Table 2 shows the flammable liquid produced.

Table 1 Composition of dehydrated sludge Table 2 Produced flammable liquid As shown in Table 2, 30% of the solids were converted to a flammable liquid with a calorific value equivalent to heavy oil, but Oil A can be separated based on the difference in specific gravity. The proportion of oil is only 17% of the total oil, indicating that the converted flammable liquid contains a large amount of substances that exist in an emulsified state and cannot be separated by specific gravity from water, or substances that are easily soluble in water. has been done.

When methylene chloride was added to the sludge before the reaction in the autoclave and the flammable liquid originally present in the sludge was extracted as a blank, the amount was 1 g.

<Example-2> 30% by weight of slaked lime was added to the same mixed raw sludge as used in Example-1, and the mixture was dehydrated with a filter press and reacted under exactly the same conditions as Example-1. Then, in the same way, the oily substance (oil A) floating on the surface of the reactant and the flammable liquid (oil B) extracted by adding methylene chloride to the reactant after collecting the oily substance are extracted. Collected.

The composition of dehydrated sludge and the generated flammable liquid are
Table 4 shows the results.

Table 3 Table 4 Produced flammable liquid As shown in Table 4, when slaked lime is added as a dehydration aid, solids can
1% converted to flammable liquid. In this case as well, the proportion of oil A that can be separated based on the difference in specific gravity is only 12%.

<Example-3> The same mixed raw sludge used in Example-1 was reacted in an autoclave under exactly the same conditions as in Example-1, and the reaction product after the reaction was cooled to room temperature, and this was placed in a laboratory centrifuge. It was separated into a liquid phase and a solid phase using a separator. Next, methylene chloride was added to each of the liquid phase and solid matter to extract the flammable liquid contained in both. The results are shown in Table 5.

As shown in Table 5, when the reactants are directly separated into a liquid phase and a solid phase using a centrifuge, 80% of the flammable liquid produced
Strongly remains in the liquid phase.

<Example-4> The same mixed raw sludge used in Example-1 was reacted in an autoclave under exactly the same conditions as in Example-1, the reaction product after the reaction was cooled to room temperature, and methylene chloride was added to the total amount of the reaction product. was added to extract all flammable liquid.

Thermogravimetric analysis was performed on the extracted flammable liquid.

The results are shown in FIG.

As shown in FIG. 3, it is clear that at temperatures below the reaction temperature, that is, 320° C., not even half of the flammable liquid produced is vaporized.

Therefore, when the reaction mixture slurry G is heat-exchanged in the preheater E and then vaporized in the gas-liquid separator H as in the conventional flow shown in Fig. 4, the vaporization temperature is assumed to be around 200°C. At low temperatures such as 20. ~2
Only about 5% evaporates.

<Calculation example> The heat balance when a flammable liquid is extracted by the method of the present invention after thermochemically reacting organic sludge was calculated as follows.

The calculation conditions are shown below.

・Reaction temperature 320℃ ・Preheating temperature 140℃ ・Dehydrated sludge moisture content 80% ・Specific heat of water I Kcal/Kg'e, specific heat of solid matter
The amount of heat per unit amount of dehydrated sludge required to heat to the reaction temperature of 0.3 Kcal/Kg'e is: 0.8 x 1 x (320-140), 2 x
Q, 3 x (320-140)'q 155Kcal
/Kg - dewatered sludge On the other hand, if the yield is assumed to be 20%, the flammable liquid produced from a unit amount of dewatered sludge is 0.2 X O,2-0.04Kg. Calorific value of flammable liquid is 8.500Kcal/K
If the heat utilization rate is 65%, it takes 75% of the total combustible liquid to heat up to the reaction temperature.

It is therefore clear that if a large proportion of the flammable liquid is lost as wastewater, energy from outside the process will be required.

In other words, if the present invention recovers as much flammable liquid as possible and uses it as fuel, there is no need to supply energy from outside the process.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are drawings showing embodiments of the present invention, respectively. FIG. 1 is an explanatory diagram showing the flow of the first invention of the present invention, and FIG. FIG. 3 is an explanatory diagram showing the flow of the second invention, and FIG. 3 is a graph showing the results of thermogravimetric analysis in Example 4, where the horizontal axis shows the temperature and the vertical axis shows the weight percent of the liquid remaining without being vaporized. show. Moreover, FIG. 4 shows a flow in a conventional method for obtaining asphalt and fuel oil from sewage sludge. 1...Organic sludge 2...Dewatering device 3...
・Dehydrated sludge 4...Press injection device 5...Preheater 6...Reactor 7...Cooler
8...Heating medium 9...Mixture slurry 1
0... Stirring tank 11... Flotation separation tank 12...
- Oily substance 13... Extraction tank 14... Solvent 15... Mixture 16... Three phase separator 17... Waste water 18... Solid matter 19.
...Extract 20...Solvent recovery device 21.
... Heating 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
3o... Mixed solution 31... Extraction device procedure amendment (voluntary) □ April 1985 ltd, Manabu Shiga, Commissioner of the Patent Office 1, Indication of the case, 1985 Patent Application No. 54204 2, Invention Name: Extraction method of flammable liquid 3, relationship with the case of the person making the amendment Patent applicant address: 5-5-16 Hongo, Bunkyo-ku, Tokyo Name:
(440) Organo Co., Ltd. Representative Nagai
Kunio Ii 4, Agent Address: 113, 812-5151 5, Please correct the following matters in the application and specification of the application subject to amendment: "A patent application pursuant to the proviso to Article 38 of the Patent Act." 1. Add the following statement to the application: "A patent application pursuant to the proviso to Article 38 of the Patent Act." 2. Add "Number of inventions stated in claims (2)" between the title of invention column and the inventor column in Book II. 3. In the 6th line from the bottom of the 3rd page and the 1st line of page 11 of the specification, "pressure equivalent to the vapor pressure at the relevant temperature" is replaced with "pressure equivalent to the water vapor pressure at the relevant temperature or higher". ” he corrected. Written amendment to the above procedures (voluntary) June 1, 1985 Michibe Uga, Commissioner of the Patent Office 1, Indication of the case Patent Application No. 54204, 1985 2, Name of the invention Method for extracting flammable liquid 3, Amendment Relationship with the case of a person who does
(440) Organo Co., Ltd. Representative Nagai
Kunio Ii 4, agent located at 113. 812-5151 Please correct the following items in the statement. 1. In the first line of page 11, "pressure equivalent to the vapor pressure at the relevant temperature" is corrected to "pressure equivalent to the water vapor pressure at the relevant temperature or higher."that's all

Claims (1)

[Claims] 1. In a method of thermochemically reacting organic sludge under high temperature and high pressure conditions to obtain a flammable liquid from the reactant, the solid matter produced by the thermochemical reaction and A method for extracting a flammable liquid, comprising adding an organic solvent to a slurry of a mixture of a flammable liquid and water, and extracting the flammable liquid using the organic solvent. 2. The method for extracting a flammable liquid according to claim 1, wherein a part of the flammable liquid floating on water in the mixture slurry is mechanically separated in advance. 3. In a method of thermochemically reacting organic sludge under high temperature and high pressure conditions to obtain a flammable liquid from the reactant, the solids produced by the thermochemical reaction, the flammable liquid, and water are flammable liquid, characterized in that the solids are first separated from the mixture slurry, then an organic solvent is added to the mixed solution of the flammable liquid and water obtained by the separation, and the flammable liquid is extracted with the organic solvent. How to extract liquid. 4. The method for extracting a flammable liquid according to claim 3, wherein a part of the flammable liquid floating on water in the mixture slurry is mechanically separated in advance.