KR100977020B1 - Apparatus and methods for successive disposal of food wastewater - Google Patents

Abstract

The present invention relates to a method for treating a food waste stripping liquid by continuously feeding the food waste stripping liquid into a closed heating pressurized reactor and maintaining the temperature and pressure of the reactor at a constant level.

The present invention also relates to an apparatus for treating food waste detachment for obtaining a large amount of solid solids from the food waste detachment.

Continuous, heated pressurized reactor, food waste, stripping solution, feed pump, solid slurry, reaction filtrate, solid solid

Description

Apparatus and methods for successive disposal of food wastewater

The present invention relates to an apparatus and a method for treating food waste, and more particularly, is used in a treatment operation for separating and removing organic solids contained in various food waste desorption liquids, and in particular, the cost and time required for the treatment operation. The present invention relates to a food waste removal apparatus and a treatment method capable of significantly shortening the waste.

Generally, food waste collected at each home or business is incinerated, landfilled, dried and fermented after removing a certain amount of water (wastewater) from the solids after a predetermined treatment process, and then recycled as organic fertilizer or compost. have. Desorption liquid of food waste is mainly generated from centrifugal dehydration, screw decanter, screw press, etc., which is a dehydration device of food waste recycling facility, and is composed of high adhesiveness and fine particle type so that dehydration efficiency is very low, so that the solid content of desorption liquid after dehydration is about 15 to It is included at 25% level. As a method of treating the desorption liquid of the food waste generated in the process of treating the food waste as described above, there are a method of directly dumping the ocean on the sea using a vessel and a water treatment using a conventional wastewater treatment facility.

Among the two wastewater treatment methods, the ocean dumping method may cause a serious problem of causing various environmental pollution at sea and destroying the ecosystem of the sea by a large amount of organic substances contained in the wastewater. In particular, due to the environmental pollution of the sea, legal regulations related to ocean dumping have been strengthened since July 1, 2007, and the water content of wastewater is more than 95%, and since January 2012, the dumping of ocean dumping is completely prohibited. Development is urgently needed.

In case of treatment through wastewater treatment facilities, consignment treatment in connection with sewage and wastewater treatment plants or self-treatment by aerobic or anaerobic methods using microorganisms may be performed. It is difficult to process due to the breakdown of, low dissolved organic concentration compared to the concentration of high organic solids.

Thermal wet oxidation technology, known as the Zimpro process, is a technology that treats sewage through a closed reactor, but an oxidant is added to oxidize the organic matter in the sewage, and ultimately CO ₂ and H ₂ O are produced. In addition, since the oxidant has to coat the inner wall of the reactor with an acid-resistant material, there is a disadvantage in that the installation cost is high.

In addition, the Republic of Korea Patent No. 550497 generates solid carbide from sewage sludge by adjusting the temperature and pressure of the heated pressurization reactor based on thermodynamic criteria to suppress the evaporation energy requirement of the water extracted from the sludge while heating the sewage sludge in the warm pressurization reactor. A method and apparatus thereof are disclosed.

However, the patent relates to a batch reaction for recovering a reactant by cooling to room temperature after the reaction is completed, and has a problem that commercialization is difficult due to large energy loss and difficulty in continuous operation. In particular, since the batch reaction device of the patent is operated sequentially, when the reaction time (HRT) is 2 hours, the processing time per day including the waiting time and the temperature rise time is approximately 12 hours, and thus the throughput is limited. There is a problem that it is difficult to commercialize because the mass processing is impossible.

According to the present invention, organic solids (fibers) and microparticles in the form of microparticles are combined from the releasing solution (high water content of 75 to 85%) of high-function food wastes containing a large amount of water (more than 60% water content) and difficult to dehydrate. It is an object of the present invention to provide an apparatus and method which can separate moisture to ensure maximum solid solids.

In addition, the present invention is to improve the problems of frequent wastewater treatment plant equipment due to the high adhesion of food waste leachate, and the problem of the limitation of the processing time and throughput of the batch treatment device of the Patent No. 551497 and the problem of energy loss. By implementing the operation in a continuous manner, it is possible to provide a method that can be mass-processed and relatively simple to separate the water through the process.

According to the present invention, the above problem has been solved by implementing a device capable of continuously adding and removing the waste food waste solution continuously.

Specifically, the present invention, the desorption liquid is continuously introduced into the warming pressurized reactor, in the reactor, the temperature and pressure of the warming pressurized reactor is thermodynamically adjusted so that the evaporation energy requirement of the water extracted from the desorption liquid is suppressed, thereby the organicity of the desorption liquid The above problem has been solved by a relatively simple method of separating the bound water from the material to prevent solidification of the highly tacky oil and to lower the viscosity of the leachate to improve fluidity.

By using the closed continuous heating pressurization reactor according to the present invention, it is possible to produce a high-calorie solid solids by separating the water from the food waste desorption solution and minimizing the loss of organic matter by heating under pressure in a reducing atmosphere, by implementing this as a continuous device There is an advantage that the food waste detachment can be more easily handled. In detail, the continuous processing apparatus and processing method of the present invention do not need a waiting time and a temperature rising time, and thus can be processed 24 hours a day, thereby reducing energy consumption and easily treating twice as much desorption solution as compared to a conventional batch processing apparatus. can do.

In addition, through the continuous heated pressurized hydrothermal decomposition process according to the present invention, the organic material is destroyed and the combined moisture with the organic material is converted into free water, which enables relatively simple separation of water through the secondary dehydration process. It is also possible to solve the problem of equipment failure due to high tack.

In addition, the solid solid produced by the method according to the present invention has a high calorific value compared to the solid product after the conventional drying process or dry pyrolysis application, has high utility value as fuel, such as waste regeneration fuel, and as a liquid product In the case of the separated reaction filtrate, solids are almost not dissolved and the water content is high, so that the wastewater can be legally discharged and the wastewater can be easily treated. In addition, the dissolved organic matter concentration (SCOD: Soluble COD) of the reaction filtrate is 100,000 mg / L or more on average, it is possible to produce methane gas through anaerobic digestion.

The present invention includes the steps of continuously introducing a desorption liquid of food waste into a heated pressurized reactor, and heating the desorption liquid of the input food waste, wherein the heating step requires evaporation energy of water extracted from the desorption liquid. It is characterized in that the temperature and pressure of the heated pressurization reactor to be suppressed thermodynamically to separate the bound water from the organic matter in the desorption liquid of the food waste, it provides a method for treating food waste desorption liquid. In addition, the present invention, the step of continuously introducing the desorption liquid of food waste into the closed heating pressurized reactor, and the reactor at a temperature of 100 to 300 ℃ for 1 to 3 hours, 1 to a specific temperature value of the temperature range Provided is a method for treating food waste detachment, comprising pressurizing above a certain saturated water vapor pressure in the range of 90 kg / cm ² .

Food waste desorbents of 75 to 85% water content (15 to 25% solids) are continuously introduced into a wet pyrolysis (warm pressurized) reactor and pressurized to above warm (100 to 300 ° C.) and saturated steam pressure at each temperature (1 To 90 kg / cm ² or more), and the reaction proceeds for about 1 to 3 hours. The organic fiber is decomposed in the food waste leachate, and the binding water, which is water, is separated, and the solid solution slurry is mixed with a low viscosity solid and a liquid reaction filtrate. Form. At this time, the moisture having a high temperature of heat inside the reactor acts as a heat medium and serves to destroy the surrounding fibrous cells together with the external heat source.

The obtained solid-liquid slurry can be solid-liquid separated through dehydration means (such as a dehydrator) and the solid solid obtained is naturally dried, so that a solid solid having a moisture content of less than 5% can be easily obtained.

Thus, the treatment method according to the present invention may further comprise the step of separating the product in the solid liquid slurry state into the solid solid and the reaction filtrate using dehydration means.

In the treatment method according to the present invention, the pressure equal to or higher than the saturated water vapor pressure is formed by the input pressure of the desorption liquid of the food waste and the vapor pressure of the low molecular weight organic material generated in the reactor and the steam pressure without a separate pressurization device. The pressure is 1.03 kg / cm ² or more saturated steam pressure at 100 ° C, 4.85 kg / cm ² or more at 150 ° C, 15.85 kg / cm ² or more at 200 ° C and 40.56 kg / cm ² at 250 ° C. It can be set at a specific pressure value of 1.03 to 87.62 kg / cm ² or more for a specific temperature value in the range of 100 to 300 ° C., in the same manner as the saturated steam pressure of not less than, saturated vapor pressure of 87.62 kg / cm ² at 300 ° C.

The treatment method according to the present invention may further comprise the step of discharging and conveying the product in the form of solid slurry produced in the reactor, wherein the step is a solid-liquid slurry when the pressure at the rear end of the reactor is above a certain level Drain and transfer out of the reactor. Temporarily releasing the relatively high pressure at the rear end of the reactor is problematic in terms of pressure drop in the reactor and in the process configuration. Therefore, it is desirable to smoothly and continuously discharge and transport the product through sequential pressure relief. .

In the treatment method according to the invention, the method may further comprise returning a portion of the reaction product in the slurry state, for example 5 to 90%, preferably 10 to 90%, to the inlet of the continuous warm pressurized reactor. Can be. As a result, not only the viscosity of the raw material introduced into the reactor is lowered, but also there is an easy advantage of raising the temperature of the raw material introduced initially by using a high temperature heat source of the product.

The present invention can increase the water content of the food waste desorption solution by decomposing the organic fibers in the food waste desorption solution by the continuous heating pressurized reactor and desorbing the bound water.

The warming pressurized reactor is operated in a closed state to suppress odor generation.

In the treatment method according to the invention, the temperature of the reactor is in the range of 100 to 300 ° C, preferably in the range of 190 to 250 ° C.

The internal pressure in the reactor is characterized in that a separate pressurization device is not necessary, and the input pressure of the raw material material by the feed pump and the evaporation pressure of some low molecular weight organic matter / water vapor are gradually increased to form a pressure above the saturated water vapor pressure. Therefore, there is no consumption of vaporized energy, thus reducing the processing cost.

Table 1 below is a thermodynamic data of the saturated steam pressure, which is the minimum required pressure to increase the reaction temperature, and as shown in FIG. 2, the pressure gradually increases as the temperature increases in the continuous reactor.

Steam / water table (unit: kcal / kg) Reaction temperature
(℃) saturation
Water vapor
(kg / cm ² ) Saturated Water Saturated Steam Vaporized Energy Water (0 ℃)-> saturated water Water (0 ℃)-> saturated steam Saturated Water-> Saturated Water Vapor 100 1.03 100.1 639.1 539 150 4.85 150.9 655.7 505 200 15.85 203.6 666.6 463 250 40.56 259.3 668.8 409 300 87.62 321.3 657.1 336

The present invention also provides an apparatus for processing the desorption liquid of food waste, the apparatus comprising a closed continuous heating pressurized reactor for receiving the desorption liquid of food waste, an agitator for stirring the desorption liquid mounted in the reactor, the reactor Temperature sensor for measuring the temperature inside, the pressure gauge for measuring the pressure inside the reactor, the temperature raising and temperature control device mounted in the reactor, the desorption liquid of food waste continuously supplied to the reactor and the solid slurry produced in the reactor A feed pump for moving to the reactor, and pressure adjusting means for discharging and conveying the product in the form of a solid slurry when the pressure at the rear of the reactor becomes a predetermined level or more.

The continuous warming pressurization reactor is a tubular reactor 21, a stirrer 22, an elevated temperature and temperature controller 23, a temperature sensor 24, a pressure gauge 25, pressure regulating means for product discharge and transport ( 28). The reactor is a conveying pump and / or pressure regulator 26 and conveying pipe 27 for conveying a portion of the reaction product in the slurry state, for example 5 to 90%, preferably 10 to 90%, to the reactor inlet. It may further include. As a result, the energy efficiency of the reactor can be improved by using the high temperature generated in the hydrothermal pressurization reactor of the food desorption liquid.

The continuous heating pressurization reactor 13 in a closed structure is, for example, a ROOF TYPE TUBULAR REACTOR.

In one embodiment of the present invention, the loop-type reactor can be manufactured using tubular pipes, so that only the reactor part can be additionally fitted according to the capacity of the feed pump 12, and the space can be easily used in a batch type (PFR). (Plug Flow Reactor) There is an advantage that the installation area is smaller than the reactor.

In one embodiment of the present invention, the stirrer 22 mounted in the continuous reactor is required to have a perfect seal, and the conventional screw shaft type stirrer by the drive shaft and the bearing leaks the reaction product in the presence of pressure. This occurs, and the present invention employs a static mixer which does not require mechanical sealing.

Peripheral devices of the closed pressurized heating reactor 13 include a feed pump 12, and in addition, a hopper 11, a product conveying pipe 14 for conveying solid slurry, and a discharge for two-stage discharge of solid slurry. The vessel 15 may further include a knock-out vessel 16 for three-stage discharge of the solid-liquid slurry, a dehydrator 17 for solid-liquid separation, and a heat recovery vessel 18 for steam heat recovery. .

In one embodiment of the present invention, the feed pump 12 boosts the pressure while continuously supplying the desorption raw material of the food waste, and employs a mono pump capable of continuously moving the solid-liquid slurry product in the reactor. Due to the high adhesiveness of the food desorption liquid, it becomes solid and sticks to the driving equipment, causing a breakdown of the equipment, and thus it is continuously introduced through the feed pump 12, thereby having the advantage of avoiding such a phenomenon.

The reactor may further contain a discharge vessel 15 and a knock-out vessel 16 and an automatic valve attached thereto at the rear end of the reactor, in order to sequentially release the pressure in addition to the pressure regulating means as necessary. The pressure regulating means 28 at the rear of the reactor automatically opens the valve to discharge the product to the discharge vessel 15 when the pressure of the reactor reaches a certain level or higher, for example, 30 kg / cm ² or more, and discharge vessel 15 For example, when water vapor pressure of 10 kg / cm ² or more is generated, the solid-liquid slurry is discharged to the knock-out container 16 at regular intervals (approximately 30 minutes) while discharging water vapor to the heat recovery vessel 18.

The knock-out vessel 16 stores the solid slurry and transfers it to the solid-liquid separation dehydration means 17. Temporarily releasing the relatively high pressure at the rear end of the reactor is problematic in the pressure drop in the reactor and in the process configuration, so that the product can be smoothly and continuously discharged and transported through the pressure release in multiple stages sequentially.

The conveying pump and / or the pressure regulator 26 is mainly a pump or device capable of conveying a portion (5 to 90%) of a solid slurry (intermediate product) in which the reaction is completed and the viscosity is low and the high temperature is preserved. It may consist of a plunge pump or a gear pump.

The reactor further includes a heat recovery vessel 18 at the end of the process, if necessary, which is mainly used to collect the saturated steam discharged from the discharge vessel 15 to be used as a heat source for drying the product in the subsequent process. That is, the present invention recovers the waste heat of the steam generated in the hydrothermal pressurization reaction of the desorption liquid of the food waste to dry the final product to increase the energy efficiency.

A continuous wet pyrolysis apparatus used in one aspect of the present invention is shown in FIG. 1.

Embodiments of the present invention are described below, which are merely illustrative to aid the understanding of the present invention, and the scope of the present invention is not limited thereto.

Example 1

Desorption of food waste

1 kg of the food waste removal liquid (water content of 84.1%, the solid content of 159 g) was wetted at a temperature of 170 ° C., 200 ° C. and 250 ° C., using a device having the same configuration as the food waste desorption liquid treatment device shown in FIG. 1. The pyrolysis reaction was advanced. The reaction pressure was maintained at a level higher than the saturated steam pressure at this temperature, thereby suppressing evaporation of the liquid product to minimize consumption of vaporization energy. The obtained solid-liquid slurry was dehydrated with a mechanical dehydrator and separated into a solid solid and a liquid reaction filtrate. 106 g (yield 66.6%) of solid solids at a reaction temperature of 170 ° C., 93.2 g (yield 58.6%) of solid solids at a reaction temperature of 200 ° C., and 43.4 g (yield 27.3%) of solid solids at a reaction temperature of 250 ° C. Each was obtained. The moisture content of the solid solids was less than 5%, and the moisture content at the low temperature drying (105 ° C. level) was at most 0%. The reaction filtrate was obtained at 693 ml at 170 ° C., 754 ml at 200 ° C. and 820 ml at 250 ° C. (see Table 2).

Example 2

Changes in Physicochemical Properties of Food Desorption Solution Before and After Heating Pressurized Pyrolysis

The physicochemical characteristics of the solid-liquid slurry obtained in Example 1 were investigated by comparing the characteristics of the food desorption solution before the hydrothermal treatment. The investigation results are shown in Table 2 below.

(a: Moisture content, b: Volatile matter, c: Fixed carbon, d: High heating value)

As a result of elemental analysis, the oxygen content was reduced from 15.9% to 10.6%, indicating that oxygen was released from the solid in the form of CO ₂ or H ₂ O. From this, the water is separated from the solids of the food desorption liquid, and the solids are carbonized to change hydrophobicity.

Example 3

Dehydration Measurement

Dehydration capacity of the solid-liquid slurry obtained in Example 1 was confirmed through CST (Capillary Suction Time). The properties of the solid slurry subjected to hydrothermal treatment at 250 ° C. are shown in Table 3 below.

 When dehydration was measured as capillary suction time (CST), dehydration was very difficult with high value of 891.5 seconds, whereas CST after treatment was significantly improved with low value of 18.3 seconds.

In addition, the ratio of SCOD (soluble COD) / TCOD (total COD) can be seen to increase from 42% to 88%, indicating that a large amount of fine particles are dissolved in the reaction filtrate as a dissolved substance. It can be confirmed that the fibrous organic material in the releasing solution was easily dissolved through the reaction in the present invention.

The present invention is devised for the desorption liquid (water content of 60% or more) of the high-functional food waste, it can be applied to food waste and sewage sludge, lignin sludge, livestock wastewater and the like having similar properties.

The continuous heated pressurized pyrolysis process according to the present invention is capable of increasing the water content of the food desorption solution through a relatively simple secondary dehydration process by converting the combined water with the organic material to free water by destroying the organic material. It is also possible to overcome the problem of equipment failure due to high adhesiveness which was a problem. In the case of the solid product, which is a final product, high calories are stored, and thus, the unit calorific value is higher than 6000 to 9000 kcal / kg. In the case of the reaction filtrate separated into a liquid product, dissolved organic matter concentration (SCOD: Soluble COD) is more than 100,000 mg / L on average, it is possible to produce methane gas through anaerobic digestion.

1 is a block diagram of a treatment process of the desorption liquid of food waste according to the present invention.

2 is a graph showing that a pressure above the saturated steam pressure is formed as the temperature rises in the continuous reactor.

Claims (12)

A circulating loop type heated pressurization reactor for receiving the leachate of food waste; An agitator for stirring the desorption liquid of the food waste mounted in the reactor; A temperature sensor for measuring a temperature inside the reactor; Manometer for measuring the pressure in the reactor; A temperature raising and temperature controlling device mounted inside the reactor; A feed pump for continuously supplying the desorption liquid of the food waste to the reactor and continuously moving the solid-liquid slurry generated in the reactor; And And a pressure regulating means for discharging and transporting the product in the form of a solid slurry when the pressure in the rear end of the reactor becomes higher than a predetermined level, the apparatus for continuous treatment of the desorption liquid of food waste. According to claim 1, In order to facilitate the input and reaction of the desorption liquid of the food waste, the conveying pump further enables to continuously return to the reactor 10 to 90% of the reaction product present in the form of a solid slurry at the rear end of the reactor A continuous treatment apparatus for food waste removing liquid, characterized in that it comprises. The device according to claim 1, wherein the pressure regulating means comprises a plurality of stages of pressure regulating device, discharge vessel and knock-out vessel for sequential pressure release. The device according to claim 1, further comprising separating means for separating the product in solid liquid slurry form into a solid solid and a liquid filtrate, respectively. According to any one of claims 1 to 3, wherein the stirrer for stirring the desorption liquid of the food waste mounted inside the reactor of the static mixer type without the shaft or bearing connected to the outside of the reactor Apparatus characterized in that the stirrer. Continuously feeding the desorption liquid of the food waste into the heated pressurized reactor, in which the reaction temperature is in the range of 1 to 90 kg / cm ² for a specific temperature value in the temperature range of 100 to 300 ° C. A method of treating food waste detachment, characterized in that it is adjusted to be above a specific saturated water vapor pressure to decompose organic fibers and to separate moisture contained in the food waste detachment. The process according to claim 6, wherein the reaction time in the continuous dosing step is 1 to 3 hours. The method of claim 6, further comprising the step of evacuating and conveying the reaction product produced in the reactor, wherein the step causes the reaction product to be discharged and conveyed out of the reactor when the pressure at the rear end of the reactor becomes above a certain level. Characterized in that, the processing method. The method of claim 8, wherein the pressure is released sequentially through multiple stages of pressure regulation. The treatment according to claim 6, wherein the pressure equal to or higher than the saturated water vapor pressure is formed by the input pressure of the desorption liquid of the food waste and the vapor pressure of the low molecular weight organic material generated inside the reactor and the vapor pressure of the water vapor without a separate pressurization device. Way. The process according to any one of claims 6 to 10, further comprising separating the reaction product in the form of a solid liquid slurry into a solid solid and a liquid filtrate, respectively, using dehydration means. The treatment apparatus according to claim 2, wherein the reaction product is continuously returned to the reactor to lower the viscosity of the raw material introduced into the reactor and to increase the temperature of the raw material initially introduced by using a high temperature heat source of the reaction product. .

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