JP2006212605A - Organic waste liquid treatment apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic waste liquid treatment apparatus and method which reduce the volume of a fertilizer component by extracting many dischargable distillates from organic waste liquid. <P>SOLUTION: In the organic waste liquid treatment apparatus 1, distilled water obtained by condensing water is obtained as purified water, and the remaining component is obtained as a liquid fertilizer from the organic waste liquid containing ammonia, ammonium salt, and water, or from digested liquid obtained by performing certain treatment of the organic waste liquid. A stock solution obtained by filtering the digested liquid etc. is sprayed onto a heated heat-transfer pipe 23 to be evaporated, and superheated steam sent into the heat-transfer pipe 23 loses latent heat to be condensed. The organic waste liquid treatment apparatus 1 comprises a concentrator 20 for sending the superheated steam obtained by the adiabatic compression of steam, evaporated when being brought into contact with the heat-transfer pipe 23, with a compressor into the heat-transfer pipe 23, a heating container 15 for supplying preheated stock solution to the concentrator 20, and a solid-liquid separator 13 for supplying the stock solution filtered after separating solid matter from the digested liquid etc. to the heating container 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention reduces the volume of organic waste liquid such as stored manure discharged from barns, so-called digested liquid after anaerobic fermentation of the organic waste liquid and extraction of methane gas, and facilitates handling such as storage and transportation. The present invention relates to an organic waste liquid processing apparatus and a processing method for producing fertilizer.

In biogas plants, biogas is collected from stored manure by anaerobic fermentation, but a large amount of nitrogen and SS remain in the digestive juice after treatment. It cannot be discharged directly into the environment. On the other hand, since the digestive juice contains a large amount of three elements, nitrogen, phosphoric acid, and potash, which are the main components of fertilizer, it is desired to effectively use this as liquid fertilizer.
Japanese Unexamined Patent Publication No. 2003-117593 (page 4-5, FIG. 1)

  However, since the digestive juice has almost no change in weight or volume from the state before collecting biogas, storage and transportation of a large amount of digestive juice has been a problem. For example, in a barn with 200 cattle, about 16 tons of stored manure is discharged per day, but the opportunity to spread it as fertilizer is about twice a year, so about 3000 tons of digestive juice for half a year is stored. An extremely large tank is required. In addition, it is sufficient if an environment in which digestive juice can be sprayed around the tank as a liquid fertilizer is required, but when spraying it on distant land, labor and cost of transportation are required. Furthermore, since the digestive juice cannot be used as a liquid fertilizer in a place where the agricultural field is small and cannot be sprayed, wastewater treatment is performed with great effort and cost.

  Therefore, in order to solve such problems, the present invention aims to provide a processing apparatus and a processing method for organic waste liquid that take out a large amount of distillable liquid that can be discharged from the organic waste liquid and reduce the volume of fertilizer components. .

The organic waste liquid treatment apparatus according to the present invention is an organic waste liquid containing ammonia and ammonium salt and water, or a digestion liquid obtained by subjecting the organic waste liquid to a certain treatment, and obtained by condensing water. Water is purified and the remaining components are obtained as liquid fertilizer. The undiluted solution obtained by filtering the digestive juice and the like is sprayed and evaporated on a heated heat transfer tube, and the superheated steam sent to the heat transfer tube is latent heat. And a condensing machine in which superheated steam obtained by adiabatically compressing vapor evaporated by touching the heat transfer tube with a compressor is sent to the heat transfer tube, and a stock solution preheated in the concentrator And a solid-liquid separator for supplying an undiluted solution obtained by separating and filtering solid components from the digested liquid and the like to the heated container.
Moreover, in the organic waste liquid treatment apparatus according to the present invention, it is preferable that the concentrator has an internal pressure reduced to a predetermined pressure by a connected vacuum pump.

On the other hand, the method for treating an organic waste liquid according to the present invention is obtained by condensing moisture in an organic waste liquid containing ammonia and ammonium salt and moisture, or a digested juice obtained by performing a certain treatment on the organic waste liquid. Distilled water is used as purified water, and the remaining components are obtained as liquid fertilizer. The solid solution is separated from the digested liquid and filtered to obtain a stock solution, and the stock solution is heated by adding sulfuric acid. And the step of preheating by stirring, and further, the stock solution in which ammonia is fixed and preheated is sprayed and evaporated on a heated heat transfer tube, and the evaporated steam is adiabatically compressed by a compressor to form superheated steam. And the step of condensing the superheated steam by removing latent heat from the superheated steam when the undiluted solution touches the heat transfer pipe and evaporates.
In the organic waste liquid treatment method according to the present invention, it is preferable that the space where the stock solution evaporates and condenses is reduced to lower the boiling point.

  Therefore, according to the organic waste liquid treatment method of the present invention, ammonia can be fixed as ammonium sulfate by adding sulfuric acid to the stock solution. It can be discharged in large quantities, and the remaining concentrated liquid can be used as liquid fertilizer. The concentrated liquid can be recovered as a liquid fertilizer while retaining the three elements, nitrogen, phosphoric acid and potash fertilizer components, which are the main components of the fertilizer, and the amount of the undiluted solution supplied to the apparatus. Compared with this, the volume can be greatly reduced.

In addition, according to the organic waste liquid treatment apparatus of the present invention, the solid content is removed from the digested liquid using a solid-liquid separator, so that the sulfuric acid necessary for pH adjustment in the concentrator is obtained. The amount can be reduced, and it becomes possible to drive at a reduced running cost.
In addition, solid-liquid separation eliminates straw and other contaminants in the stock solution that circulates the concentrator, preventing clogging of finely structured heat transfer tubes and maintaining without reducing operating performance. Will also be easier.
Furthermore, according to the organic waste liquid processing apparatus and processing method according to the present invention, the inside of the concentrator is decompressed by a vacuum pump, evaporation and condensation of the stock solution is reduced, and latent heat is recovered from the steam pressurized by the compressor. The amount of heat required for operation could be reduced.

Next, an embodiment of an organic waste liquid treatment apparatus and treatment method according to the present invention will be described below with reference to the drawings. In the biogas plant, as described above, biogas such as CH ₄ , CO ₂ , H ₂ S, and H ₂ is collected from the stored manure discharged from the barn. In the organic waste liquid treatment apparatus of the present embodiment, the filtrate obtained by separating the solid content by applying the digested liquid obtained from the biogas plant to a solid-liquid separator (hereinafter, the filtrate thus obtained is referred to as “raw solution”). It is intended to separate into concentrated liquid containing fertilizer components and purified water that can be discharged into general rivers.

  FIG. 1 is a diagram conceptually showing an embodiment of an organic waste liquid treatment apparatus. First, the structure of the organic waste liquid treatment apparatus 1 will be described. The organic waste liquid treatment apparatus 1 has a digestive liquid tank 11 for temporarily storing digestive liquid sent from a biogas plant, to which a metering pump 12 for sending a predetermined amount of digestive liquid to the secondary side is connected. Has been. A solid-liquid separator 13 is connected via the metering pump 12. For example, a filter press, a screw press, or a centrifugal decanter is used as the solid-liquid separator 13. This is because, by separating the digested liquid into solid and liquid, handling such as transfer and spraying can be facilitated in a later concentration step by evaporation.

  The solid-liquid separator 13 is connected to a compost tank 14 for storing the solid content separated and discharged from the digested liquid, and further preheats the stock solution from which the solid content has been removed from the digested liquid. A heating container 15 is connected. The heating container 15 is provided with a stirring blade and a heater in a tank capable of storing a certain amount of stock solution, and is charged with sulfuric acid for fixing ammonia and adjusting pH as will be described later. A concentrator 20 is connected to the heating container 15 via a pump 16. The concentrator 20 is connected to a pipe so that the stock solution supplied to the lower tank 21 is sent to the upper evaporator 22 by the pump 17 and circulated. However, the liquid fertilizer tank 31 is also connected to the lower tank 21 via the three-way valve 18 in a switchable state.

  The concentrator 20 is configured such that the stock solution is sprayed in the evaporator 22 and the falling stock solution is heated by the heat transfer tube 23, but the heat transfer tube 23 is generated in the evaporator 22 and compressed and heated. It is comprised so that steam may be sent. That is, a steam pipe 24 is connected to the evaporator 22, and a compressor 25 for pressurizing the generated steam by adiabatic compression is provided therein. Therefore, in the concentrator 20, the steam adiabatically compressed by the compressor 25 is sent to the heat transfer tube 23, and the raw liquid sprayed on the heat transfer tube 23 is touched to generate new steam, while in the heat transfer tube 23. The superheated steam is constructed so that latent heat is taken away and condensed. In the concentrator 20, the stock solution that has passed through the heat transfer tube 23 without evaporating returns to the lower tank 21 and circulates as it is.

  Further, the concentrator 20 of this embodiment is configured to evacuate the inside so as to lower the boiling point. That is, a vacuum pump 26 is connected to the concentrator 20, the inside is maintained at a pressure of 25 kPa abs., And evaporation and condensation of the stock solution are performed near 65 ° C., which is the boiling point of water at the same pressure. . Therefore, in particular, a structure for reducing the burden on a heating device (not shown) provided outside the system that constantly heats the heat transfer tube 23 to evaporate the stock solution and conversely, a cooling device for condensing the superheated steam. ing.

  By the way, the heat transfer tubes 23 constituting the concentrator 20 are installed in units of several hundred in order to increase the contact area with the sprayed stock solution. As described above, the heat transfer tube 23 condenses the superheated steam and is also configured as a condenser. Therefore, the concentrator 20 includes a condenser 27 that condenses the vapor and collects the distillate, and is provided with an auxiliary tank 28 that stores the obtained distillate. A purified water tank 30 is connected to the auxiliary tank 28 via a pump 29.

Next, a treatment method performed by the operation of the organic waste liquid treatment apparatus 1 will be described. In addition, the organic waste liquid processing apparatus 1 of this embodiment is provided with a controller (not shown) having a control program for automatically operating the processing of the organic waste liquid described below.
The digested liquid sent from the biogas plant is temporarily stored in the digested liquid tank 11, and a predetermined amount of digested liquid is sent to the solid-liquid separator 13 by the metering pump 12. In the solid-liquid separator 13, the stock solution from which the solid content has been removed by centrifugation is sent to the heating container 15, and the solid content such as straw scraps is placed in the compost tank 14. The solid content thus sent to the compost tank 14 is used as fermented compost containing inorganic nitrogen, phosphorus, and potash.

  In the heating container 15, the stock solution is heated by a heater while being stirred and preheated. At this time, sulfuric acid is put into the heating container 15 for pH adjustment. Therefore, ammonia nitrogen in the stock solution is mixed with sulfuric acid to become ammonium sulfate (ammonium sulfate), and is sent to the lower tank 21 of the concentrator 20 together with the stock solution by driving the pump 16. Also, in the biogas plant, carbon dioxide is generated when methane is recovered and is dissolved in the digestive juice in a saturated state. Therefore, if the stock solution is stirred, the carbonic acid will evaporate and expand, but if sulfuric acid is added, it will foam immediately, so there will be no foaming in the subsequent evaporation step.

The stock solution in the lower tank 21 thus preheated is then sent to the evaporator 22 by driving the pump 17. The stock solution is sprayed onto the heat transfer tube 23 from above, and part of the stock solution evaporates by touching the surface. The sprayed undiluted solution falls while touching the heat transfer tubes 23 arranged in the vertical direction, and those that have not evaporated return to the lower tank 21 and circulate again. At the start of operation, superheated steam is temporarily sent to the heat transfer tube 23 from outside the system, thereby causing evaporation of the stock solution that has touched the heated heat transfer tube 23.
Since the inside of the concentrator 20 is evacuated and depressurized to 25 kPa abs., The stock solution evaporates at about 65 ° C. And the vapor | steam which contacted the heat exchanger tube 23 and evaporated is sent to the heat exchanger tube 23 in the pressurized state, since the adiabatic compression by the compressor 25 is performed in the middle of the steam tube 24.

  Therefore, the superheated steam in the heat transfer tube 23 is condensed by removing the latent heat when the stock solution sprayed in the evaporator 22 touches the heat transfer tube 23, and the distillate is stored in the auxiliary tank 28. It is sent to the purified water tank 30 by driving. By the way, this distillate contains nitrogen because the ammonia and ammonium ions contained in the stock solution are immobilized as ammonium sulfate when sulfuric acid is added to the stock solution in the heating vessel 15. Absent. Therefore, the distillate can be discharged as it is into purified water. On the other hand, the ammonium sulfate fixed by sulfuric acid and the concentrated liquid remaining in the lower tank 21 without becoming the distillate are sent to the liquid fertilizer tank 31 by switching the three-way valve 18.

  Therefore, according to the organic waste liquid processing apparatus 1 and the processing method of the present embodiment, since the sulfuric acid is added to the stock solution to be fixed as ammonium sulfate, the concentrator 20 does not contain a nitrogen content. Distilled water can be discharged in large quantities, and the remaining concentrated liquid can be used as liquid fertilizer. The concentrated liquid can be recovered as a liquid fertilizer while retaining the three elements, nitrogen, phosphoric acid and potash fertilizer components, which are the main components of the fertilizer, and the amount of the undiluted solution supplied to the apparatus. Compared with this, the volume could be greatly reduced.

  Further, in the present embodiment, the inside of the concentrator 20 is depressurized to 25 kPa abs. By the vacuum pump 26 so that evaporation and condensation of the stock solution is performed at around 65 ° C., and latent heat is recovered from the steam pressurized by the compressor 25. As the stock solution was evaporated, the consumption of heat required for operation could be reduced. Here, FIG. 2 compares the amount of heat (kW) required to distill 1000 kg / hr of water. That is, a comparison was made between what distilled water by latent heat recovery using the compressor 25 as in this embodiment and what distilled water by generating steam with a boiler without using the compressor 25. As is clear from this, the amount of heat consumed in the boiler was large, and when the compressor 25 was used, the amount of heat consumed could be reduced to about one-twentieth compared to when the compressor 25 was not used.

As mentioned above, although one Embodiment was described about the processing apparatus and processing method of the organic waste liquid concerning this invention, this invention is not limited to this, A various change is possible in the range which does not deviate from the meaning. .
Although the case where the digestive liquid obtained from the biogas plant is processed has been described in the above embodiment, the organic waste liquid itself which is not subjected to anaerobic fermentation performed in a biogas plant or the like may be processed.

It is the figure which showed notionally 1st Embodiment of the organic waste liquid processing apparatus. It is the figure which showed the comparison of the calorie | heat amount (kW) required in order to distill 1000 kg / hr water as a table | surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic waste liquid processing apparatus 11 Digestion liquid tank 12 Metering pump 13 Solid-liquid separator 14 Compost tank 15 Heating container 16,17,29 Pump 18 Three-way valve 20 Concentrator 21 Lower tank 22 Evaporator 23 Heat transfer pipe 24 Steam pipe 25 Compression Machine 26 Vacuum pump 27 Condenser 28 Auxiliary tank 30 Water purification tank 31 Liquid fertilizer tank

Claims (4)

For organic waste liquid containing ammonia and ammonium salt and water, or digested liquid that has been subjected to a certain treatment on the organic waste liquid, distilled water obtained by condensing water is used as purified water, and the remaining components are obtained as liquid fertilizer. In the organic waste liquid treatment device,
The raw solution obtained by filtering the digestive juice and the like is sprayed on a heated heat transfer tube to evaporate, and the superheated steam sent to the heat transfer tube is deprived of latent heat and condensed, and the vapor evaporated by touching the heat transfer tube A concentrator that sends superheated steam obtained by adiabatic compression with a compressor to the heat transfer tube;
A heating vessel for supplying a preheated stock solution to the concentrator;
An apparatus for treating an organic waste liquid, comprising: a solid-liquid separator for supplying a stock solution obtained by separating and filtering a solid content from the digestive juice or the like to the heating vessel. In the processing apparatus of the organic waste liquid of Claim 1,
2. The organic waste liquid treatment apparatus according to claim 1, wherein the concentrator has an internal pressure reduced to a predetermined pressure by a connected vacuum pump. For organic waste liquid containing ammonia and ammonium salt and water, or digested liquid that has been subjected to a certain treatment on the organic waste liquid, distilled water obtained by condensing water is used as purified water, and the remaining components are obtained as liquid fertilizer. In the organic waste liquid treatment method,
A step of separating the solid from the digestive juice and obtaining a filtered stock solution;
A step of preheating the stock solution by adding sulfuric acid and heating and stirring;
Furthermore, the stock solution in which ammonia is fixed and preheated is sprayed on a heated heat transfer tube to evaporate, and the evaporated steam is adiabatically compressed by a compressor and is sent to the heat transfer tube as superheated steam. And a step of removing latent heat from the superheated steam and condensing the superheated steam when the undiluted solution comes into contact with the heat transfer tube and evaporates. In the processing method of the organic waste liquid of Claim 3,
A method for treating an organic waste liquid, wherein the boiling point is lowered by decompressing a space in which the stock solution evaporates and condenses.

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