JP2015123428A - Waste treatment system and waste treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent reduction in the recovery efficiency of energy held by solid waste (refuse) in a waste treatment system equipped with a heat recovery device such as a boiler.SOLUTION: A system of the present invention comprises: a waste pit 4 for storing solid waste 2; a waste water tank 6 for storing waste water 5 separated from the solid waste 2 in the waste pit 4; a waste incinerator 7 for firing the solid waste 2 from which the waste water 5 is separated; a heat recovery device 8 for recovering heat generated by firing the solid waste 2 in the waste incinerator 7; and solid-liquid separator 9 for separating a solid content contained in the waste water 5 separated from the solid waste 2.

Description

  The present invention relates to a waste treatment system and a waste treatment method for treating solid waste containing moisture.

  The position of the waste incineration plant is changing from the conventional waste incineration treatment facility to the heat recovery facility from the viewpoint of preventing global warming and effectively utilizing the energy stored in the waste. Based on such a background, heat generated by combustion of garbage in a garbage incinerator is used as a heat source of a boiler, for example.

  By the way, sewage generated at the time of waste storage in a waste pit of a waste incineration plant is generally spray-evaporated in a high temperature portion in the waste incinerator (see Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 10-339421 Japanese Patent Laid-Open No. 5-118525

  Conventionally, as described above, since sewage is spray-evaporated in the high temperature portion of the waste incinerator, a part of heat generated by combustion of the waste in the waste incinerator is taken away as latent heat of evaporation of sewage. For this reason, there exists a problem of bringing about the fall of the collection | recovery efficiency (heat recovery efficiency) of waste holding energy.

  The present invention has been made in view of the above-described problems of the prior art, and in a waste treatment system equipped with a heat recovery device such as a boiler, a reduction in the recovery efficiency of retained energy of solid waste (garbage). The purpose is to prevent.

  In order to solve the above problems, the present invention provides a waste treatment system for treating solid waste containing moisture, a waste pit for storing the solid waste, and the waste pit in the waste pit. A sewage tank for storing sewage separated from solid waste, a waste incinerator for incinerating the solid waste from which sewage is separated, and combustion of the solid waste in the waste incinerator And a solid-liquid separation device for separating solids contained in the sewage separated from the solid waste.

  Preferably, the solid-liquid separation device includes a screen.

  Preferably, the screen has an opening of 5 mm to 30 mm.

  Preferably, the solid-liquid separator includes a wet cyclone.

  Preferably, the solid-liquid separator further includes a pretreatment facility for changing the property of the sewage from which the solid content has been separated into a property suitable for treatment in a sewage treatment plant.

  In order to solve the above problems, the present invention is a waste treatment method using any one of the waste treatment systems described above, wherein the waste water separation step separates the waste water from the solid waste in the waste pit. And a solid-liquid separation step of separating the solid content contained in the sewage by the solid-liquid separation device, and a solid content re-input that re-injects the solid content separated in the solid-liquid separation step into the waste pit And a process.

  In order to solve the above problems, the present invention is a waste treatment method using any one of the waste treatment systems described above, wherein the waste water separation step separates the waste water from the solid waste in the waste pit. A solid-liquid separation step of separating the solid content contained in the sewage by the solid-liquid separation device, and a mixing process of mixing the sewage separated in the solid-liquid separation step with sewage in a sewage treatment plant And a process.

  Preferably, the method further includes a solid content recharging step of recharging the solid content separated in the solid-liquid separation step into the waste pit.

  Preferably, the method further includes a pretreatment step for changing the property of the sewage to a property suitable for treatment in the sewage treatment plant before mixing the sewage with the sewage.

  Preferably, the weight of the sewage separated in the sewage separation step is 5% or more of the weight of the solid waste containing the moisture.

  ADVANTAGE OF THE INVENTION According to this invention, in the waste processing system provided with heat recovery apparatuses, such as a boiler, the fall of the collection | recovery efficiency of the retained energy of solid waste (garbage) can be prevented.

The schematic diagram which showed schematic structure of the waste-treatment system by one Embodiment of this invention. The flowchart of the waste disposal method by one Embodiment of this invention.

  Hereinafter, a waste disposal system and a waste disposal method according to an embodiment of the present invention will be described with reference to the drawings.

  A waste treatment system 1 according to this embodiment shown in FIG. 1 is a system for treating waste (solid waste) 2 containing moisture, and includes a waste incineration plant 3.

  The waste 2 carried into the waste incineration plant 3 is stored in a waste pit (waste pit) 4. The waste 2 stored in the waste pit 4 contains moisture, and the sewage 5 separated from the trash 2 is stored in the sewage tank 6.

  The waste 2 stored in the waste pit 4 is carried into a waste incinerator (waste incinerator) 7 and incinerated. The heat generated by the combustion of the waste 2 in the waste incinerator 7 is used as a heat source for the boiler (heat recovery device) 8.

  The waste incineration plant 3 in the present embodiment includes a solid-liquid separation device 9 for separating solids contained in the sewage 5 separated from the trash 2 and stored in the sewage tank 6.

  That is, the sewage 5 in the sewage tank 6 is conveyed to a screen 10 which is one of the solid-liquid separators 9, where the solid content and the liquid are separated. The opening of the screen 10 is 5 mm to 30 mm. The overflow 11 of the screen 10 is reintroduced into the garbage pit 4. The sewage 5 that has passed through the screen 10 is conveyed to a wet cyclone 12 that is one of the solid-liquid separators 9.

  The drainage liquid 13 of the wet cyclone 12 is reintroduced into the garbage pit 4. The treatment liquid 14 of the wet cyclone 12 is conveyed from the waste incineration plant 3 to the sewage treatment plant 15. The sewage treatment plant 15 is provided with a pretreatment facility 17 for changing the property of the sewage 5 to a property suitable for treatment in the sewage treatment plant 15 before mixing the sewage 5 (treatment liquid 14) with the sewage 16. Yes. The sewage 5 treated in the pretreatment facility 17 is mixed with the sewage 16 and treated in the sewage treatment plant 15. The pretreatment facility 17 can also be installed on the waste incineration plant 3 side.

  Next, a waste processing method using the above-described waste processing system 1 will be described with reference to FIG.

  This waste treatment method 20 is included in the sewage 5 by the sewage separation step S1 for separating the sewage 5 from the waste (solid waste) 2 in the waste pit 4, and the screen 10 and the wet cyclone 12 as the solid-liquid separation device 9. Before mixing the sewage 5 with the sewage 16, the solid-liquid separation step S2 for separating the solid content, the solid content re-feeding step S3 for re-feeding the solid content separated in the solid-liquid separation step S2 into the waste pit 4 The sewage pretreatment step S4 for changing the property of the sewage 5 to a property suitable for treatment in the sewage treatment plant 15 and the sewage 5 treated in the sewage pretreatment step S4 are mixed with the sewage 16 in the sewage treatment plant 15. Sewage / sewage mixed treatment step S5 to be treated.

  The weight of the sewage 5 separated in the sewage separation step S1 is 5% or more of the weight of the waste (solid waste) 2 containing moisture.

  Further, in the waste treatment method according to the present embodiment, the dewatered sludge 18 generated in the sewage treatment plant 15 is transported to the waste incineration plant 3 by a transport vehicle, and the waste 2 and the dewatered sludge 18 are co-fired in the waste incinerator 7. To do. The transport vehicle that transports the dewatered sludge 18 from the sewage treatment plant 15 to the waste incineration plant 3 transports the treatment liquid 14 of the wet cyclone 12 to the sewage treatment plant 15.

  As described above, according to the waste treatment system 1 and the waste treatment method 20 according to the present embodiment, the waste is separated from the waste (solid waste) 2 stored in the waste pit 4 and stored in the sewage tank 6. The sewage 5 is not spray-evaporated in the waste incinerator 7 as in the prior art, but the solid content is separated by the solid-liquid separation device 9 comprising the screen 10 and the wet cyclone 12, and then the sewage 16 in the sewage treatment plant 15. Therefore, it is possible to avoid the loss of latent heat of evaporation due to the spray evaporation process in the incinerator for the sewage 5. Thereby, the energy which garbage (solid waste) 2 holds can be collected more efficiently than before.

  Moreover, since the spray evaporation process in the incinerator of the sewage 5 is not performed, the spray apparatus in the sewage furnace that has been necessary in the past becomes unnecessary.

  In addition, since the solid content in the sewage 5 is separated and removed by the solid-liquid separator 9 and then mixed with the sewage 16, the processing burden at the sewage treatment plant 15 can be reduced.

  In addition, since the overflow 11 of the screen 10 and the drainage liquid 13 of the wet cyclone 12 which are the solid-liquid separator 9 are reintroduced into the waste pit 4, when setting the operating conditions of the solid-liquid separator 9, the overflow 11 and It is possible to consider only reducing the solid content concentration in the treatment liquid 14 of the wet cyclone 12 without considering increasing the solid content concentration in the drainage liquid 13.

  In addition, before mixing the sewage 5 with the sewage 16, the pretreatment facility 17 that is a primary treatment facility dedicated to sewage treatment can change the property of the sewage 5 to a property suitable for treatment in the sewage treatment plant 15. Even if the property of the treatment liquid 14 from the wet cyclone 12 is not suitable for the mixing treatment in the sewage treatment plant 15, the sewage 5 can be appropriately treated in the sewage treatment plant 15.

  In addition, since the generation amount of the sewage 5 is considerably smaller than the generation amount of the sewage 16, the influence on the sewage treatment plant 15 is slight, and the pretreatment facility 17 dedicated to the sewage treatment can be a compact facility. .

  In addition, by using a transport vehicle that transports the dewatered sludge 18 from the sewage treatment plant 15 to the waste incineration plant 3, the sewage 5 and the sewage 5 can be transported to the sewage treatment plant 15 from the waste incineration plant 3. The conveyance of the dewatered sludge 18 can be made efficient.

  Below, the heat balance example in the waste disposal system 1 by this embodiment and the conventional waste incineration system is shown.

1) Preconditions ・ People population 300,000 ・ Waste generation amount 300ton / day (1kg / person / day)
・ Waste properties Low heating value 1,500kcal / kg (imported waste)
Sewage generation amount 10% of incoming waste
Water latent heat of vaporization 600kcal / kg
・ Sewage generation amount 90,000m ³ / day (300 liters / person / day)
・ Dehydrated sludge generation amount 60ton / day ・ Dehydrated sludge properties Moisture 80%
Combustible content 12%
Combustible component lower heating value 5,000kcal / kg

2) Estimation of heat balance
Conventional example (spray evaporation treatment in sewage furnace)
The lower heating value of the waste and dewatered sludge that is put into the waste incinerator is
(1,500 × 300 + (5,000 × 0.12−600 × 0.8) × 60) ÷ (300 + 60) = 1,270kcal / kg
Estimated low calorific value of dewatered sludge: 5,000 × 0.12−600 × 0.8 kcal / kg
If the power generation efficiency is 15%, the power generation output is
360 × 1,000 ÷ 24 × 1,270 × 0.15 ÷ 860 = 3,320kW
Throughput per hour: 360 x 1,000 ÷ 24 kg / h

This embodiment (sewage is treated at a sewage treatment plant)
In this embodiment, there is no latent heat loss due to spray evaporation in the sewage furnace, so the latent heat of vaporization is added to the heat balance.
(1,500 × 300 + 300 × 0.1 × 600 + (5,000 × 0.12−600 × 0.8) × 60) ÷ (300 × 0.9 + 60) = 1,440kcal / kg
Evaporation latent heat: 300 × 0.1 × 600 kcal / kg
Amount of treatment: 300 x 0.9 t / d ← Reduces dirty moisture If the power generation efficiency is 16%, the power generation output is
330 × 1,000 ÷ 24 × 1,440 × 0.16 ÷ 860 = 3,680kW

Comparison between this embodiment and the conventional example When comparing the power generation amount of this embodiment and the power generation amount of the conventional example,
3,680 ÷ 3,320 = 1.11
That is, this embodiment can be expected to increase power generation by 10% or more compared to the conventional example.

The amount of sewage generated is
300 x 0.1 = 30 tons / day → 1/3000 of sewage generation (30 ÷ 90,000)
The impact on the sewage treatment plant is small.

1 Waste treatment system 2 Garbage (solid waste)
3 Garbage incineration plant 4 Garbage pit (waste pit)
5 Wastewater 6 Wastewater tank 7 Waste incinerator (waste incinerator)
8 Boiler (heat recovery device)
DESCRIPTION OF SYMBOLS 9 Solid-liquid separator 10 Screen 11 Overflow 12 Wet cyclone 13 Wet cyclone waste liquid 14 Wet cyclone treatment liquid 15 Sewage treatment plant 16 Sewage 17 Pretreatment equipment 20 Waste treatment method S1: Sewage separation process S2: Solid-liquid separation process S3: Solid content re-input step S4: Sewage pretreatment step S5: Sewage / sewage mixed treatment step

Claims (10)

In a waste treatment system for treating solid waste containing moisture,
A waste pit for storing the solid waste;
A sewage tank for storing sewage separated from the solid waste in the waste pit;
A waste incinerator for incinerating the solid waste from which the sewage has been separated;
A heat recovery device for recovering heat generated by combustion of the solid waste in the waste incinerator;
A waste treatment system comprising: a solid-liquid separation device for separating a solid content contained in the sewage separated from the solid waste.   The waste treatment system according to claim 1, wherein the solid-liquid separation device includes a screen.   The waste treatment system according to claim 2, wherein the screen has an opening of 5 mm to 30 mm.   The waste treatment system according to any one of claims 1 to 3, wherein the solid-liquid separation device includes a wet cyclone.   5. The apparatus according to claim 1, further comprising a pretreatment facility for changing the property of the sewage from which the solid content has been separated in the solid-liquid separator to a property suitable for treatment in a sewage treatment plant. Waste treatment system. A waste disposal method using the waste disposal system according to any one of claims 1 to 5,
A sewage separation step of separating the sewage from the solid waste in the waste pit;
A solid-liquid separation step of separating the solid content contained in the sewage by the solid-liquid separation device;
A solid content re-introducing step of re-introducing the solid content separated in the solid-liquid separation step into the waste pit. A waste disposal method using the waste disposal system according to any one of claims 1 to 5,
A sewage separation step of separating the sewage from the solid waste in the waste pit;
A solid-liquid separation step of separating the solid content contained in the sewage by the solid-liquid separation device;
A waste treatment method comprising: a mixing treatment step of treating the sewage separated in the solid-liquid separation step with sewage in a sewage treatment plant.   The waste disposal method according to claim 7, further comprising a solid content re-injection step of re-injecting the solid content separated in the solid-liquid separation step into the waste pit.   The waste treatment method according to claim 7 or 8, further comprising a pretreatment step for changing the property of the wastewater to a property suitable for treatment in the sewage treatment plant before mixing the wastewater with the sewage. The waste treatment method according to any one of claims 6 to 9, wherein the weight of the wastewater separated in the wastewater separation step is 5% or more of the weight of the solid waste containing the moisture.

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