JP2011020060A - Garbage disposal system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for drying garbage without discharging a malodor outside the system while saving energy. <P>SOLUTION: The garbage 2 micronized and dehydrated in a pretreatment process 1 is supplied to a garbage drying treatment system as dehydrated garbage Ga1. That is, it is supplied to a dryer 6 and dried by hot air HA of ≥100°C supplied to the dryer 6, the dried garbage is discharged as dry garbage Ga2, volatile matters are discharged as a fuel gas G through a modifying apparatus 9 in a gasification furnace 8, a gas engine 10 is driven by the fuel gas G, and power is generated by a power generator 11. In the meantime, an exhaust gas LA1 which has absorbed moisture to a saturated state in the dryer 6 is gas-liquid separated in a gas-liquid separator 16 through a heat exchanger 7 and a condenser 15, and dry air LA3 from which the moisture is removed is heated by a high temperature exhaust gas WG from the gas engine 10 and supplied to the dryer 6 as the hot air HA. Thus, the air for drying is circulated and made to flow in a closed circuit and the malodor is not leaked to the outside of the system. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a garbage processing system, and more particularly, to a system for drying garbage with high energy efficiency.

Garbage, mainly food residues, is practically difficult to dispose of at low cost such as dumping and landfilling from the viewpoints of environmental pollution prevention and hygiene. In addition, disposal methods that directly incinerate garbage with high water content require a large amount of fuel, and there are many problems such as generation of pollutants due to low-temperature combustion.
For this reason, in the treatment of garbage, many treatment methods for effectively using (recycling) the garbage in some form such as heat recovery and composting have been implemented.

For recycling of garbage, composting / feeding treatment, drying treatment, gasification treatment, and a system combining these treatments have been proposed.
Here, in composting / feeding, the moisture content of raw garbage is 80% or more, whereas for the premise of composting, the moisture content is about 60% and it is necessary to make it into feed. The water content needs to be 20% or less. For this reason, a considerable expense is required for drying using heat energy, addition of a moisture adjusting agent, and the like. Also, while garbage is generated mainly in urban areas, compost and feed as recycled products are consumed by farmhouses in the suburbs, resulting in transportation costs and uneconomical as a garbage recycling system. It must be a thing.

In any case, the recycling system is premised on the implementation of a drying process that reduces the moisture content of the garbage to a value corresponding to a predetermined recycling system.
When recycling garbage, it is necessary to remove the moisture while retaining the components of the garbage in order to maintain its usefulness. For example, carbonization in which volatile components (flammable gas) are scattered and drying by bioprocessing in which nutrients as feed are decomposed are unsuitable. Considering the above points, as a drying method suitable for garbage recycling, low-temperature drying at 120 ° C. or lower, or short-time bioprocessing that does not decompose organic components can be considered.

As the low temperature drying, vacuum drying or the short-time bio-drying can be considered. Among these, vacuum drying is uneconomical because of the high cost of the device itself and the running cost of the device operation.
Biodrying uses the exothermic action of the bacteria, so the cost of the heat source for heating can be greatly reduced, but it is necessary to maintain a certain moisture content in order to set up an environment where the bacteria can work effectively, and the equipment becomes larger and Increases operating costs.

Regarding the treatment of garbage, for example, the following inventions have been proposed in view of the drawbacks and advantages of the above method.
JP 2003-154331 A JP-A-2005-211719

  According to the invention described in the above-mentioned patent document, it is possible to expect certain effects such as saving energy in drying garbage and increasing the efficiency of drying.

Each system including the above-mentioned patent documents has respective advantages, but as a common disadvantage, there is a problem of malodor generated in the process.
Since the exhaust discharged during the drying process of kitchen waste has a bad odor, it is essential to take measures against deodorization such as heating and exhausting the exhaust and deodorizing with a deodorizer. This is a major cause of the low economics of the drying system. Further, even if the above deodorizing measures are taken, the odor itself cannot be completely removed, and the deodorization process is only completed when the odor component in the exhaust gas is set to a legal value or less.

  The present invention is configured in view of the above-described problems, and is based on the premise that drying of garbage is performed by a heated gas such as heated air, and the flow path of the heated gas is a closed path. The heated gas circulates and flows in the system and is not discharged out of the system. This basically eliminates the deodorizing means and simplifies the drying system. Further, a means for exchanging heat with waste heat discharged from the engine or the like and a gas-liquid separation means are arranged in the gas flow path to adjust the humidity of the heated gas.

  A heated gas such as heated air is used as a heat source for drying garbage, and this heated gas circulates and flows in a closed circuit, and basically does not discharge out of the system. There is no need to provide a deodorizing means, and the apparatus constituting this system can be provided in a small and inexpensive manner.

  In addition, it is possible to gasify dried garbage and generate power with an engine using this gas as fuel, thereby controlling the system using this electricity, and energy can be saved in this respect as well. .

Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a pretreatment process of garbage before reaching the present system, and this system is installed subsequent to the pretreatment process 1.

First, an outline of the pretreatment process 1 will be described, and then a system according to the present invention will be described.
The garbage 2 is refined by a refinement mechanism 3 and dehydrated by a dehydrator (cylinder press machine or the like) 4. For example, when the miniaturization mechanism 3 is an apparatus that shears and refines garbage with a rotating blade and the dehydrator 4 is a cylinder press machine, the power required by the miniaturization mechanism 3 and the dehydrator 4 is 1000 kg / The time is about 10 kw (equivalent to 8600 kcal).

For example, if the moisture content of garbage 2 is 80% and this moisture content is reduced to 70% via the refining mechanism 3 and the dehydrator 4, the dewatering amount of 1000kg of garbage 2 is 330kg. . In this case, if the garbage 2 is dried by heating without dehydration at all, the amount of heat necessary for drying is approximately 620 kcal / kg. Therefore, the amount of heat necessary for dehydrating 330 kg of the same amount of water is as follows: It becomes.
330 × 620 = 204,600 kcal
When dehydration of the same amount of water is performed by the finer mechanism 3 and the dehydrator 4, as described above, the difference in heat amount is 196,000 kcal. By installing the pretreatment step 1, the garbage is dried. Can achieve significant energy savings.

Next, a waste water treatment device 5 is installed following the dehydrator 4 in the pretreatment step 1.
Since the wastewater dehydrated in the pretreatment step 1 contains high-concentration pollutants, the wastewater treatment apparatus 5 performs wastewater treatment. As a wastewater treatment method, a decomposition process using microorganisms using a biofilm can be realized stably and at a low price, and the costs of all treatment processes including a garbage drying process described later can be kept low.

  The garbage (hereinafter referred to as “dehydrated garbage”) Ga1 whose moisture has been reduced in the pretreatment step 1 is put into a kiln-type dryer 6 and dried. The heat source for drying is the warm air HA supplied to the dryer 6, but for convenience of explanation, the process for generating the warm air HA will be described later. First, the dehydrated garbage Ga1 is dried by the warm air HA. This will be explained from the state.

  The dried garbage Ga1 introduced into the dryer 6 through the inlet 6a is dried by the hot air HA supplied to the dryer 6. Specifically, the hot air HA supplied to the dryer 6 absorbs the vapor evaporated from the dehydrated garbage Ga1 in the dryer 6 to the saturated water vapor amount and decreases the temperature, and is discharged from the dryer 6 as exhaust LA1. To the heat exchanger 7. As will be described later, the exhaust gas LA1 is supplied to the dryer 6 again as hot air HA around the closed circuit, so that the drying air circulates and flows in the closed circuit. The hot air HA is air having a temperature of 120 ° C. or lower.

When air is heated and cooled in the closed circuit, moisture is removed as follows.
For example, if the temperature of the heated air HA is 100 ° C., the saturated steam amount is 564.1 g / m ³ , and if it is 30 ° C., the saturated steam amount is 30.4 g / m ^3. In addition, if hot air HA heated to 100 ° C. is supplied to the dryer 6 and the exhaust gas LA1 discharged from the dryer 6 is cooled to 30 ° C., about 534 g / m ³ of water can be removed. By sequentially heating and cooling, the garbage can be dried by the air circulating in the closed circuit.

  The dried garbage Ga2 which has been dried and discharged from the discharge port 6a of the dryer 6 is recovered in the gasification furnace 8 as a volatile component as fuel gas. That is, in this system, the garbage in the dryer 6 is dried at a relatively low temperature as described above in a state containing the volatile components, and the volatile components are recovered as fuel gas in the subsequent gasification furnace 8. It is the composition to do.

That is, the gas recovery by the above-mentioned method is to recover the volatile components by heating the dry garbage, so that the apparatus can be made small and simple.
For example, compared to a biogasification system using microorganisms, the apparatus can be formed in a very small size, and delicate control is not required for operation of the apparatus. In the gasification by carbonization, volatile components are released by pyrolysis, and combustion of this gas is used as a heat source for pyrolysis, but the residue remaining finally by pyrolysis is only carbon. However, the carbon content derived from garbage cannot be used as a general fuel because the composition is coarse and powdery.

Next, the produced gas G ′ discharged from the gasification furnace 8 becomes a reformed gas G suitable for fuel in the reformer 9 and is supplied to a gas engine 10 such as a diesel system. It is operated using G as fuel, and the generator 11 is driven to generate electricity.
Since the residue Ga3 from which volatile components have been extracted in the gasification furnace 8 is odorless and has been sterilized in effect by the high temperature of the gas extraction process, the subsequent handling is easy and safe.

  The high-temperature exhaust gas WG discharged from the gas engine 10 reaches a heater 13 that forms part of the hot air generator 12, heats the gas-liquid separated air to be described later, and then discharges outside the system through the exhaust gas treatment means 14. Is done.

  On the other hand, the exhaust gas LA1 that has absorbed the moisture of the dryer 6 and has reached a substantially saturated vapor amount is heat-exchanged with air LA3 (hereinafter referred to as “dry air”) LA3 described later in the heat exchanger 7. The air LA2 that has exited the heat exchanger 7 is cooled in the condenser 15, whereby the saturated steam amount is reduced and the contained moisture is condensed. In the gas-liquid separator 16, the moisture of the air LA is removed to become dry air LA3. This dry air LA3 reaches the hot air generator 12 through the heat exchanger 7 as described above, and exchanges heat with the high-temperature exhaust gas WG. As a result, for example, the hot air HA having a high temperature of about 120 ° C. and dried is supplied to the dryer 6 again.

As described above, the air including the hot air HA as a heat source for drying the garbage circulates and flows in the closed circuit and is not discharged out of the system.
Here, since odor components such as bad odor diffuse using air as a medium, it is possible to almost completely prevent the bad odor from leaking outside the system unless the air containing the bad odor flows out to the outside.
In addition, if the gas that circulates and flows is replaced with air and an inert gas such as nitrogen gas, there is no fear of ignition even if an abnormal temperature rise occurs in the gas flow path. Nitrogen gas needs to be purchased differently from air, but once it is supplied into the route, virtually no replenishment is required, so the economic burden is small.

FIG. 2 shows a second embodiment.
A water level sensor 17 is disposed in the gas-liquid separator 16, and water level data output from the sensor 17 is output to the control device 18. Reference numeral 19 denotes a temperature sensor disposed in the vicinity of the hot air discharge section of the hot air generator 12, and air temperature data measured by the temperature sensor 19 is also output to the control device 18.

  In the above configuration, when the control device 18 receives a signal from the water level sensor 17 that the water level in the gas-liquid separator 16 has reached a predetermined value or more, the control device 18 opens the valve 20 provided in the drain line, The moisture W separated from the exhaust LA2 is discharged. The discharged water W reaches the wastewater treatment device 5 in the pretreatment step 1 and is detoxified by this device.

  On the other hand, the temperature sensor 19 constantly monitors the temperature of the hot air HA discharged from the hot air generator 12 and is arranged in a power supply circuit connected to the generator 11 when the measured temperature is equal to or lower than a preset temperature. The switch SW thus closed is closed, and electric power E is supplied to the electric heater 21 as an auxiliary heat source to raise the temperature of the hot air HA to a set value. Since these controls are relatively simple, a normal personal computer is sufficient as the control device 18.

  The system described above has a smaller thermal load on the components that make up the system compared to the microbial bio system, incineration system, etc., and does not require a large facility like the microbial bio system. It can be configured as one possible device, and can be installed at each business establishment that discharges garbage, such as a factory that manufactures food such as frozen food and retort food.

  As described above, the system can be compactly formed as one device, but each element can be configured as a plant with a large capacity and a large size.

It is a systematic diagram of the garbage drying system which shows the 1st Example of this invention. It is a systematic diagram of the garbage drying system which shows the 2nd Example of this invention.

DESCRIPTION OF SYMBOLS 1 Pretreatment process 2 Garbage 3 Refinement mechanism 4 Dehydration device 5 Waste water treatment device 6 Dryer 7 Heat exchanger 8 Gasification furnace 9 Gas reforming means 10 Gas engine 11 Generator 12 Hot air generator 13 (Engine waste heat) ) Heater 14 Exhaust gas treatment means 15 Condenser 16 Gas-liquid separator 17 Water level sensor 18 Control device 19 Temperature sensor 20 Valve 21 Electric heater E Electricity (electric power)
G Reformed fuel gas G 'Fuel gas Ga1 Dehydrated garbage Ga2 Dry garbage Ga3 (Dry garbage) Carbon content HA Hot air LA1, LA2 Exhaust LA3 Dry air WG (Gas engine) Exhaust

Claims (7)

A system for drying raw garbage, in which hot air is supplied as a heat source and moisture carrying means to a dryer for drying dehydrated garbage whose moisture has been reduced in the previous process, and the gas as hot air is a closed circuit A gas-liquid separator that cools the gas discharged from the dryer to remove moisture in the gas, and the gas-liquid separator discharged from the gas-liquid separator. A garbage processing system comprising: means for heating dry gas to form the warm air; and drying the dehydrated garbage by circulating and flowing the gas in a closed circuit. A gasification furnace is arranged after the dryer. A gas engine using the gas discharged from the gasification furnace as fuel is connected to the gasification furnace, and the exhaust gas discharged from the gas engine is a gas heating means. The garbage processing system according to claim 1, wherein the circulating and flowing gas is heated in a hot air generator. The garbage processing system according to claim 2, wherein a generator is connected to the gas engine. 4. The raw air generator according to claim 3, wherein the hot air generator is provided with an electric heater as auxiliary heating means, and the electric heater is configured to be supplied with electric power generated by a generator connected to the gas engine. Garbage disposal system. A temperature sensor is disposed in the hot air generator, and a circuit of a power source for the electric heater is appropriately set so that the temperature of the hot air becomes a preset temperature corresponding to the temperature of the hot air detected by the temperature sensor. The garbage disposal system according to claim 4, wherein the garbage disposal system is configured to open and close. A water level sensor is disposed in the gas-liquid separator, and a drainage pipe is connected to the gas-liquid separator, and the drainage pipe is connected to a wastewater treatment apparatus that forms part of the pretreatment process. A valve is provided in the pipeline, and the water level in the gas-liquid separator is set within a certain range by opening and closing the valve in response to the water level signal detected by the water level sensor. Item 1. A garbage disposal system according to item 1. The garbage processing system according to claim 5 or 6, wherein the control is automatically controlled by a control device.

Images