WO2008100012A1

WO2008100012A1 - Method for recovering resource from waste and resource recovery system therefor

Info

Publication number: WO2008100012A1
Application number: PCT/KR2007/006766
Authority: WO
Inventors: Suk-Mok Song; Hi-Saeng Kang
Original assignee: Changkwang Co Ltd
Current assignee: Changkwang Co Ltd
Priority date: 2007-02-15
Filing date: 2007-12-21
Publication date: 2008-08-21
Anticipated expiration: 2009-08-15

Abstract

A method for recovering resource from waste comprises: a first step for decomposing waste into ash and reformed gas by performing a partial- combustion, a thermal decomposition, and a reforming process with using only oxygen; a second step for pre-processing the ash obtained in the first step; a third step for recycling the ash pre-processed in the second step into resource by a melting process; a fourth step for recovering sensible heat of the reformed gas obtained in the first step, and separating sooty carbon from the reformed gas by a dust-collecting process thereby recycling the sooty carbon into active carbon in an another process; a fifth step for purifying the reformed gas having undergone a dust- collecting process in the fourth step into clean fuel gas by neutralization, desulfurization, and absorption processes, and recycling waste water produced as a byproduct; and a sixth step for utilizing the clean fuel gas obtained in the fifth step. Accordingly, the amount of pollutants contained in final disposal to atmosphere are minimized, and all of the waste is recycled into useful resource. Also, the operation cost (running cost) is reduced significantly.

Description

METHOD FOR RECOVERING RESOURCE FROM WASTE AND RESOURCE RECOVERY SYSTEM THEREFOR

Technical Field

[1] The present invention relates to a method for recovering resource from waste, and a resource recover system therefor, and more particularly, to a method for recovering resource from waste by performing an integrated process in an optimum operating conditions, and a resource recovery system therefor. Background Art

[2] Generally, various waste materials such as municipal waste, industrial waste, medical waste, and commercial waste are generated in a daily life. If the waste is not properly processed, environmental disruption is caused and resource is wasted. Accordingly, it is important to processing the waste thus to protect the environment and to recover resource from the waste.

[3] The conventional method for processing waste has been developed as following four steps.

[4] In a first step, waste is simply buried.

[5] In a second step, the waste is incinerated by using air thus to exhaust combustion gas, and then remaining ash is buried.

[6] In a third step, the waste undergoes a process of thermal decomposition-incineration by using air, heat recovery -harmful pollutants reduction, and the generated combustion gas is vented, and the remaining ash is recycled into harmless melted aggregate.

[7] In a fourth step, the waste undergoes a process of thermal decomposition-reforming by using oxygen, heat recovery-harmful pollutants reduction, generated Fuel Gas by thermal-decomposition is recycled into useful Raw Gas for multipurpose utilization, and remaining ash is recycled into harmless melted aggregate. That is, both combustible organic materials and ash are recycled.

[8] Currently, all of the first to fourth steps are utilized. However, the former steps more influence on environmental disruption. Accordingly, many of institutions and companies are competitively performing researches in order to practicalize the method for processing waste by the latter steps.

[9] In Japan, the third step has been commercialized since the late 1970s. In Europe, the fourth step has been commercialized since the early 1990s. Recently, other methods similar to the Fourth step method have been commercialized or under developing.

[10] However, as shown in the following table 1, the aforementioned methods are required to be improved in an economic aspect, an eco-friendly aspect, a stable and easy aspect for operating the system, a durable aspect of high temperature equipments, etc.In Korea, many related institutions and companies are trying to develop techniques for recovering resource from waste. However, practical techniques have not been disclosed.

[H] [Table 1] [12] showing features of recent techniques by the third and fourth steps.

[13]

[14]

[15] T-proces Europe: Constitutions: A surface s Thermo-Sel 1 . Combustible component: Melting method : ect undergoes partial-oxidation Most of the ash

-thermal decomposition melting by -purification process by using combustion heat pure oxygen, and then is of a fuel-oxygen recycling into useable fuel gas. burner in a

2. Ash: undergoes a melting bottom of vertical and recovering process into decomposer and resource by using combustion the melts are heat of fuel-oxygen burner. continuously discharging.

Characteristics:

1 . An installation cost is increased and a thermal decomposition reaction speed is lower due to an application of a pressurizing-jacket heating- injecting device for waste.

2. Operation conditions for a reforming furnace causes to increase operation & construction cost.

3. A melting furnace volume shall be larger flat type for make uniform the quality of melt.

4. A low cost is implemented in construction and -operation aspects etc.

[16] In Korea, many related institutions and companies are trying to develop techniques for recovering resource from waste. However, practical techniques have not been disclosed. [17] Accordingly, the present applicant has researched the above techniques, and has obtained many Korean and foreign patents. The patents have been registered as a new technique by the Korean government, and foreign registered patents are as follows. [18] 1. Korean Registered Patent No. 0466408 (An apparatus and method for totally recycling various kind of waste into harmless resources) [19] 2. Korean Registered Patent No. 0515917 (A melting apparatus for totally recycling each kind of Ash from waste into harmless inorganic resource) [20] 3. Korean Registered Patent No. 0606395 (A pre-processing apparatus and method for recovering resource from Bottom ash & Fly ash by a melting process) [21] 4. Japanese Registered Patent No. 3921198 (A melting apparatus for totally recycling various kind of Ash from waste into harmless inorganic resource) [22] Also, the Korean government has been issued certificates as a new technique as follows;

[23] The Article No. 104:

[24] A new technique defined by the Ministry of Environment [25] (A technique for Melt Bath melting type furnace of Bottom & Fly ashes from municipal waste, constituted with Graphite Crucible where retains certain amount of melt always, & Multi-Face Heating type such as upper-face is heating by high temperature radiation heat from oxygen-fuel burner and the bottom & discharge face are heating by electrical resistance heat which controlled automatically) Disclosure of Invention Technical Problem

[26] Therefore, it is an object of the present invention to provide a method for recovering resource from waste capable of minimizing environmental disruption due to harmful materials included in waste, and capable of recycling waste into useful resource, and a resource recovery system therefor.

[27] More concretely, the present invention is to provide a method for recovering resource from waste and a resource recovery system therefor capable of efficiently recovering resource from waste by optimized operating conditions of a thermal decomposer and a reformer (operating temperature, reacting time, steam injecting amount, etc.), in which each operating characteristic is implemented and an operation cost is reduced in a process for recycling combustible organic materials included in waste into fuel gas, and an amount of harmful materials such as dioxin and heavy metal that remain in a finally exhausted material are able to decrease extremely.

[28] It is still another object of the present invention to provide a method for recovering resource from waste and a resource recovery system therefor capable of enhancing an energy efficiency by implementing a main process and subsidiary processes to produce secondary and third products into one integrated process, capable of supplying a self consumption utility, and capable of utilizing a total amount of resource by self usage plus outside usage of surplus energy. Technical Solution

[29] The present invention is to provide a method for recovering resource from waste, comprising: a first step for decomposing waste into ash and reformed gas by performing partial oxidation, a thermal decomposition, and a reforming process with using only oxygen; a second step for pre-processing the ash obtained in the first step; a third step for recycling the ash pre-processed in the second step into resource by a melting process; a fourth step for recovering a sensible heat of the reformed gas obtained in the first step, and separating co-generated carbon from the reformed gas by a dust collecting process thereby recycling the carbon into active carbon & recover heavy metal and a fifth step for purifying the reformed gas having undergone a dust removing process in the fourth step into clean fuel gas by means of acid gas neut- ralization-desulfurization-high grade adsorption process. [30] The method may further comprise a sixth step for producing at least one or more of power, steam, oxygen, and petrol chemical products by using the clean fuel gas generated in the fifth step.

[31] The first step may include obtaining ash and thermally-decomposed gas by partial oxidation in a Thermal Decomposer; and obtaining reformed gas by reforming the thermally-decomposed gas in a Reformer so as to perform an additional thermal decomposition at elevated temperature.

[32] When operating conditions, such as operating temperature of a Reformer outlet into

95O⁰C- 1050⁰C, a reacting time of 4-6 seconds, an injected amount of steam for acceleration of a thermal decomposition corresponding to 1-1.5 times of a stoichiometric amount, are used in the reforming step, so that make results to operating cost down & minimizing pollutant emission.

[33] In the second step, a metallic material is separated from the ash for recover as resource, and remained ash crushed to powder, and flux is added for lowering melting temperature if necessary.

[34] The third step may include completely combusting a remaining unburned component and roasting by oxygen-fuel burner, at an other rotary kiln type Roasting Furnace, and the roasted ash are fed to a Melting Furnace where all of the ash are melted and discharged to Water Quenching Bath, thereby making into aggregate.

[35] The fourth step may include recovering sensible heat from the reformed gas at Waste

Heat Recovery Boiler; and the boiler exit gas temperature is controlled to appropriately for next processing at Temperature Control Apparatus, and fed to Dust Collector where most of the dust (sooty carbon & fly ashes) are separated, and the dust separated (mostly fine carbon) shall be further treated for produce active carbon & recover heavy metal & separate waste water which treated at Waste Water Treating System together with waste water formed at fifth step.

[36] The fifth step may include cooling, neutralizing-washing the reformed gas having been dust (carbon) removed in the fourth step; boosting gas pressure the neutralized and washed carbon-removed gas; and desulfurizing the boosted carbon-removed, neutralizing, and washing gas in a Desulfurizing Tower having a catalyst therein; and producing clean fuel gas and waste water which formed during this processing due to condensing of excess water vapor in the gas and absorbing of any impurities remained in the gas ; and the waste water shall be further treated together with waste water comes from the Active Carbon Producing Unit, at the Waste Water Treatment Unit for recover heavy metal, complex salt and industrial water.

[37] In the step of cooling, neutralizing-washing, the temperature of gas is firstly cooled down to 60°C~80°C by injecting spray water at Quench Tower, and 2ndly cooled down to 4O⁰C by circulating alkaline washing water which circulating from Neutralizing- Washing Tower bottom to top thru the circulation pump, filter & cooler under counter current contact to the gas, and mean while the gas is cleaned & cooled.

[38] Oxygen produced in the sixth step shall be used as oxidant for partial oxidation of waste & thermal decomposed fuel gas so as to supply a heat amount necessary at the first and third steps.

[39] The present invention is also to provide a resource recovery system, comprising: a

Thermal Decomposer for thermally decomposing fed waste into ash and thermally- decomposed gas; a Reformer connected to the Thermal Decomposer, for reforming the thermally-decomposed gas produced from the Thermal Decomposer; a Waste Heat Recovery Boiler connected to the Reformer, for recovering a sensible heat of the reformed gas and generating steam; a Temperature Control Apparatus connected to the Waste Heat Recovery Boiler, for lowering a temperature of the reformed gas; a Dust Collector connected to the Temperature Control Apparatus, for removing dust (carbon & fly ash) from the reformed gas thus collecting, and exhausting the carbon-removed reformed gas; an Active Carbon Producing Unit connected to the Dust Collector, composed of a heat treatment apparatus, a condenser & separators, for producing active carbon & separate heavy metal and waste water; a Quenching-Neut- ralizing-Washing Tower connected to the Dust Collector, for quenching , neutralizing and washing the carbon-removed gas; a Booster connected to the Quenching-Neut- ralizing-Washing Tower, for boosting the neutralized and washed carbon-removed gas; a Desulfurizing Tower connected to the Booster, for desulfurizing the boosted gas by using a catalyst; a Reservoir for storing clean fuel gas generated from the Desulfurizing Tower; an Ash Pre-treatment Unit connected to the Thermal Decomposer, for pre-processing the ash separated from Thermal Decomposer; a Roasting Furnace (rotary kiln type) connected to the Ash Pre-treatment Unit for roasting the ash; a Melting Furnace connected to the Roasting Furnace for melting the roasted ash; and a Quench Water Bath connected to the Melting Furnace for quenching the melted ash thereby making into aggregate.

[40] The resource recovery system, using clean fuel gas stored in the Reservoir, may further comprise at least one of; a Gas Engine Power Generating Unit; a Gas Boiler for producing steam; and an Oxygen Generating Apparatus for producing oxygen by using the generated electricity, and applicable as feed stock for producing so many kind of petro-chemical product whenever necessary.

Advantageous Effects

[41] The present invention has the following effects.

[42] First, since oxygen rather than air is used as an oxidizer, a high temperature environment is easily implemented, and a combustion-thermal decomposition speed is fast. Furthermore, since the amount of gas to be processed is 1/6 of the conventional one to be incinerated, a fabrication cost for each device is reduced, thermal efficiency is greatly enhanced, and a function for processing harmful components is enhanced. Furthermore, since a source for producing nitrogen oxide is removed, installation and operation costs for a nitrogen oxide removing device are neglected.

[43] Second, since energy recovered in the process is not thermal energy but clean fuel gas which is chemical energy, the clean fuel gas can be easily stored and transmitted, and can be totally utilized. Furthermore, when the clean fuel gas is to be converted into power, converting efficiency (power generating efficiency) obtained by using the Gas Engine or the Gas Turbine is increased by more than two times than the conventional efficiency obtained by using a steam turbine.

[44] Third, since the processing is performed in the reduction atmosphere, the toxic pollutant dioxin is hardly formed. Even though the dioxin formed mostly absorbed by the carbon contained in the processing gas at the Dust Collector and shall be decomposed to harmless components at the Active Carbon Producing Unit. And the fast cooling processing at the Temperature Control Apparatus and the Quench tower may result in minimizing effect of dioxin re-forming. Thus the amount of the dioxin finally exhausted becomes negligible.

[45] The heavy metal having a high boiling point is mostly contained in the vitrified melted slag which is not dissolved at the natural atmospheric conditions, thus not to cause pollution. However the heavy metal having a low boiling point is mostly sublimated to gas phase and recovered as concentrated small amount at the Active Carbon Producing Unit and Waste Water Treatment Unit, and it is easily recycled or discarded.

[46] Also, since another few each kind of harmful gas undergoes high-leveled purifying processes such as a wet scrubbing process by alkaline solution, a desulfurizing process by the catalytic reaction and by a high grade of adsorbing process, so that the finally exhausted amount of the harmful gas is small enough to be ignored. Accordingly, an eco-friendly effect can be obtained.

[47] Fourth, each unit process for totally recovering resource from waste, and processes for producing secondary and third products such as power, steam, oxygen, and active carbon are implemented as one integrated process, thereby enhancing an energy efficiency by the process.

[48] Fifth, since the operating conditions of the reforming furnace is optimized, the operating cost is reduced and the effect to remove harmful components is up-graded.

[49] Sixth, since the above effects are combined to each other, the overall effect of preservation the resource and the environment can be maximized, and a future worth effect as an oil substitution and mass & energy recycle industrial society shall be also certainly expected.

Brief Description of the Drawings

[50] FIG. 1 is a block diagram showing a method for recovering resource from waste according to the present invention;

[51] FIG. 2 is a view specifically showing each step of FIG. 1;

[52] FIG. 3 is a block diagram showing a process for recovering heavy metal from carbon and producing active carbon;

[53] FIG. 4 is a block diagram showing a process for recovering heavy metal and complex salt from waste water, and producing usable industrial water;

[54] FIG. 5 is a block diagram showing a power generating process by a single gas engine or a combined cycle (gas turbine + steam turbine) system; and

[55] FIG. 6 is a block diagram showing an oxygen producing process.

Best Mode for Carrying Out the Invention

[56] Hereinafter, the method for recovering resource from waste and the resource recovery system therefor according to the present invention will be explained in more detail.

[57] FIG. 1 is a block diagram showing a method for recovering resource from waste according to the present invention, FIG. 2 is a view specifically showing each step of FIG. 1, FIG. 3 is a block diagram showing a process for recovering heavy metal from carbon and producing active carbon, FIG. 4 is a block diagram showing a process for recovering heavy metal, complex salt, and producing usable water, from waste water. FIG. 5 is a block diagram showing a power generating process by a Gas Engine or a combined cycle (gas turbine-steam turbine), and FIG. 6 is a block diagram showing an oxygen producing apparatus.

[58] As shown in FIG. 1, the method for recovering resource from waste according to the present invention comprises a first step for decomposing waste into reformed gas and ash by a thermal decomposition process and a reforming process (SlO); second and third steps for processing the ash generated in the first step SlO (S20 and S30); and fourth and fifth steps for producing clean fuel gas by processing the reformed gas generated in the first step SlO (S40 and S50). The method may further comprise a sixth step for producing secondary (electricity, steam) and third products (oxygen, petroleum chemical products) by using the primary product (clean fuel gas) produced in the fourth and fifth steps S40 and S50.

[59] In the first step SlO, fed waste is partially combusted, thermally decomposed, and reformed. The first step SlO, as shown in FIG. 2, is performed at the Thermal Decomposer and the Reformer. Before the first step SlO, waste undergoes a preprocessing such as separating useful material, crushing for large size materials, mixing for quality equalizing, and deodorizing process. The waste having been pre-processed is fed into the Thermal Decomposer by a certain amount with a constant rate. The Thermal Decomposer is a horizontal rotary type furnace, and an Oxygen Burner (not shown) for supplying oxygen to the Thermal Decomposer is installed at an opposite side of the Thermal Decomposer. Oxygen injected at the first step SlO for partial oxidation may be supplied from the sixth step S60 that will be later explained. A fogging water supplying device (not shown) is connected to the Thermal Decomposer for control prevent over heating.

[60] The waste having been supplied to the Thermal Decomposer sequentially undergoes a drying-evaporation-thermal decomposition-combustion pattern, thereby being decomposed into ash and thermally-decomposed gas. That is, moisture and combustible organic materials included in the waste are completely gasified thus to be partially combusted and thermally decomposed. Then, the moisture and combustible organic materials included in the waste become gas having 300°C~600°C, and incombustible inorganic materials become ash having 600°C~800°C. The thermally-decomposed gas is exhausted to the Reformer, an 'S '-shaped vertical fixed furnace. The thermally-decomposed gas having been inputted to the Reformer is thermally decomposed at elevated temperature of 95O⁰C- 1050⁰C by additionally supplied oxygen, thereby becoming reformed gas. While the ash is dropped into a vertical cooling device (not shown) connected to another end of the Thermal Decomposer, the ash is cooled to have a temperature of 6O⁰C or less than by the fogging water supplying device (not shown). Then, the ash is supplied to the Ash Pre-treatment Unit of the second step S20 that will be later explained. In the first step SlO, an injection amount of oxygen is controlled so that the temperature of thermally-decomposed gas exhausted from the Thermal Decomposer can be maintained in a range of 300°C~600°C. Also, fogging water is injected into the Thermal Decomposer so that a highest combustion temperature in the Thermal Decomposer can be controlled not to exceed approximately 1100⁰C. An injection amount of waste is also controlled so that an amount of unburned components included in the exhausted ash is 5% or less than.

[61] As aforementioned, the thermally-decomposed gas is exhausted under a condition that an amount of oxygen, fogging water, and unburned components are controlled, in the atmosphere which corresponds to a reduction condition having lack of oxygen. In the first step SlO, the thermally-decomposed gas contains a large amount of sooty carbon and heavy hydrocarbon due to an incomplete thermal decomposition degree, and harmful components contained in the waste such as chlorine, sulfur, and nitrogen are converted into HCl, H₂S, and NH₃. Also, in the first step SlO, heavy metal vapor having a low boiling point is contained in the gas phase by sublimation, also some of heavy metal having a high boiling point & ash are contained as fine particles by flying thereof are mixed together with decomposed gas phase. That is, heavy metal having a low boiling point is sublimated thereby to become gas, whereas heavy metal having a high boiling point is not sublimated (evaporated) thereby part of it to fly as a particulate & most of it remain in the ash. Most of the heavy metal having a high boiling point shall be contained in the final product of aggregate as non soluble state in the natural atmospheric conditions, thereby pollution problems shall be negligible. In the reduction atmosphere, since a dioxin-based very toxic materials are known as inhibition effect for formation, so that the final content in the disposals will be negligible.

[62] In order to additional decomposition and reforming reaction, the thermally-decomposed gas entering to the Reformer, is tempered to in a range of 95O⁰C- 1050⁰C at outlet temperature, in accordance with additional oxygen feeding which produce combustion heat by partial oxidation of the decomposed gas, and the amount of oxygen is automatically controlled. Further more for accelerate reforming reactions, a certain amount of steam is injected into the Reformer. The amount of steam injection is 1-1.5 times of a stoichiometric amount necessary to a reforming reaction. Also, an injection amount of waste is controlled so that a reaction time required in the reforming reaction can be in a range of 4-6 seconds. However, it is preferable to control a temperature of the reformed gas exhausted from the Reformer and to control a steam injection amount and reaction time in a reforming reaction until the component of tar disappears completely. When apply excessive operational conditions, such as the higher temperature of reformer outlet, the more amount of steam feeding and the longer reaction times, the degree of reforming reaction shall be accomplished more, however it will result to the higher operational cost, make hard operability and the shortening the life time of refractory, so that it is preferable to maintain optimized conditions as mentioned in a range of above.

[63] In the first step SlO, most of combustibles in the waste are decomposed into mono molecule gas such as H₂, CO, CO₂, and H₂O, but certain amount of sooty carbon and heavy hydrocarbons such as methane ethane, propane etc., are not completely decomposed yet at the Thermal Decomposer, and additional higher grade of decomposition and equilibrium reactions are performed as mentioned above at the Reformer, and the reformed gas passes through the Waste Heat Recovery Boiler, Temperature Control Apparatus & Dust Collector sequentially in the fourth step S40 that will be later explained. Meanwhile, most of the trace of toxic Dioxin gas and harmful heavy metal vapor or particles contained in the reformed gas are separated from gas stream by the adsorption effect of the fine carbon particles which remained in the reformed gas, and dust separator (Bag Filter). This function is one of very important reason why sooty carbon to be controlled to remain in the gas stream. [64] On the other hand, the incombustible ashes, metals and some of remained unburned combustibles are discharged all-together to outside from the opposite side of the Thermal Decomposer through the cooling device where they are cooled down to ambient temperature by latent heat of evaporation of fogging water feeding.

[65] The second and third steps S20 and S30 for recycling ash separated in the first step

SlO will be explained, and then the fourth, fifth, and sixth steps S40, S50 and S60 for recycling reformed gas will be explained.

[66] As shown in FIG. 2, the second step S20 is an Ash Pre-treatment Unit which consist of separating device of useful metal from bulky ash by magnetic and eddy current devices, crushing device of coarse clinkers by hammer or roller crushers up-to certain fine particles, feeding device of flux which effect to lowering melting temperature and vitrification at the Melting Furnace such as waste glass chip, sand, calcium oxide etc., and ashes which collected from the bottom of Reformer, Waste Heat Recovery Boiler and Temperature Control Apparatus, if necessary, .mixing device for equalizing the quality of multi components and final Ash Storing Vessel for short time storage. The purpose of this system are to make better efficient operation at the subsequent process such as, easy to complete combustion of remained unburned combustibles at the Roasting Furnace, easy for melting at the Melting Furnace and operational independent flexibility in between the gasification part (from Thermal Decomposer up-to produce clean fuel gas; S-10, S-40 & subsequent process in Fig 1 ) and ash melting part(.S-30 in Fig 1).

[67] In the third step S30, the ash from the Ash Pre-treatment Unit in the second step S20, is roasted, melted, quench-crushed and recycled into resource. And, as shown in FIG. 2, the system consists of Roasting Furnace (rotary type kiln), Melting Furnace & Water Quenching Bath. The Roasting Furnace is connected to the Ash Storing Vessel in the ash pre-treatment of the second step S20, the Melting Furnace is connected to the Roasting Furnace, and the Water Quenching Bath is connected to the Melting Furnace. The ash in the Ash Storing Vessel in the second step S20 is continuously fed to the Roasting Furnace, where the ash is heated and oxidized completely any of remained combustibles by count current contact with the oxygen rich hot fluid formed from oxygen-fuel gas burner which installed opposite side of the Roasting Furnace, Then the roasted ash automatically falls down to the Melting Furnace at the temperature level 1000⁰C and the flue gas exhausted to the Thermal Decomposer or Reformer at the temperature level 1200⁰C.

[68] The ash introduced into the Melting Furnace is floated initially on the high temperature melt bath which full filled with melt in the Special Crucible made by graphite. And the ash melted slowly by the high temperature radiation heat flux (1700⁰C) generated from oxygen-fuel burner which installed on direct upper side of melt bath. Then, the molten melt are flow tothe direction of overflow weir located opposite side of crucible through the channel provided on bottom of melt bath by siphon principle and the melt overflow from the weir to the outside vertical space. The vertical space is heated always by few of electrical heating element (so called kantal heater) in a range of 1300-1500⁰C for maintain the well constant fluidity of the melt. Meanwhile the outside horizontal space of the crucible bottom wall is also heated by another few of electrical heating element (so called SiC heater) in a range of 1300-1500⁰C for keep constant well fluidity of the melt, so that the molten melt are flow very smoothly without any interruptions by bad fluidity or solidification during the ash melting processing. Normally the melting time is required 2 to 4 hours depending on the ash properties.

[69] Then, the molten melt discharge from overflow weir fall down directly into the water in the Quench Water Bath through the vertical space, and crushed automatically due to thermal shock by rapid quenching, and the cooled & crushed slag is continuously discharge to outside and utilized as resource of civil works or inorganic raw materials. Mean time, the temperature of water in the Quench Water Bath is automatically controlled by circulating cooling water.

[70] As the Melting Furnace of the present invention, a melting apparatus for totally recycling various kind of waste into harmless resources having the Korean Registered Patent No. 0515917 is preferably used. However, the present invention is not limited to the melting apparatus. The method for recovering resource from waste and the resource recovery system thereof according to the present invention may have an enhanced performance by adding an ash pre-treatment process by the Ash Pre- treatment Unit to the melting apparatus having the Korean Registered Patent No. 0515917, in which the melting heat load at the Melting Furnace is reduced, the melting temperature is lowered, and a melting time is also reduced.

[71] Hereinafter, a process for recycling reformed gas and a resource recovery system therefor will be explained.

[72] The process for recycling reformed gas according to the present invention further comprises a fourth step S40 and a fifth step S50, and may further comprise a sixth step S60, if necessary.

[73] In the fourth step S40 in Fig 1, are provided the Waste Heat Boiler where the sensible heat of the reformed gas recovered, the Temperature Control Apparatus where the gas temperature regulated to be suitable for next processing, the Dust Collector where all of the solid particles contained in gas including sooty carbon and fly ashes are separated from gas stream and transferred to the Active Carbon Producing Unit.

[74] More in details, the reformed gas exhausted from Reformer of the first step SlO at

95O⁰C- 1050⁰C, is introduced to the Waste Heat Recovery Boiler where the sensible heat of the gas is recovered up-to 300⁰C by producing steam. Then the gas temperature is reduced to about 200⁰C at the Temperature Control Apparatus by latent heat of evaporation of fogging water for providing suitable conditions at next processing, and the gas feed to the Dust Collector for separating all of solid particles from gas stream. Simultaneously most of the harmful vapor of Dioxin and Heavy metals are also separated from gas stream by absorbing effect of fine carbon particles contained in the gas & deposited on the Dust Collector. And the dust collected are further treated for produce active carbon, recover heavy metals and decompose dioxin as shown Fig 3, where the dust firstly heated to around 900⁰C for activating the carbon, evaporating heavy metal and decomposing dioxin respectively, and the vapor evaporated is condensed by cooling for recover heavy metal, and any non-condensible gas is sent to the Thermal decomposer or Reformer, and the condensate after recover heavy metals are sent to Waste Water Treatment Unit, meanwhile the activated carbon is also produced as resources. Then, the clean gas dust removed is sent to next further purifying process.

[75] In the fifth step S50, the gas carbon-removed from the Dust Collector is purified into clean fuel gas and is recycled into resource. As shown in FIG. 2, the fifth step S50 consists of Quench Tower where the gas cooled down by spray water, Neutralizing - Washing Tower where the acidic gas contained in gas are neutralized and cooled to ambient temperature by week alkaline solution, Boosting Blower which for inducing the gas from upstream to downstream and pressurize the gas, Desulfurizer where the Hydrogen sulfide removed by catalytic reaction, and Waste Water Treatment Unit where the waste water treated to harmless water, and the purified clean fuel gas is stored tentatively for utilize as resources of energy and so many kind of mass production. .

[76] More in details, the dust removed gas is cooled firstly to 60-80⁰C at Quench Tower by evaporation latent heat & sensible heat of spray & fogging water, and the pre- cooled gas is introduce to Neutralizing-Washing Tower. Where the most of acidic gas are neutralized to the complex salt by washing with circulating NaOH alkaline solution, through the circulation pump, filter, cooler & pall ring packed tower. Simultaneously most of the excess water vapor in the gas phase is condensed and some of remained heavy metal vapor and dust also absorbed to the circulating solution. Meanwhile, the excess water formed by condensing is sent to Waste Water Treatment Unit, and the gas purified and cooled to 4O⁰C is sent to Boosting Blower, and the heat formed by condensing & cooling are continuously removed at cooler by another circulating cooling water system. The gas exhausted from the Neutralizing-Washing Tower is boosted by Blower for inducing the gas stream form upstream and sent to downstream and the gas is fed to Desulfurizer. Where the gas is treated for removing hydrogen sulfide (H₂S) by catalytic reaction with iron oxide catalyst, which packed in the tower, and the clean fuel gas is stored in a Storage Tank tentatively for utilize as resources of various energy & mass productions. However the clean fuel gas may be further treated by appropriate higher grade purification system depending on the purpose and requirements (not shown in Fig). And, the de-activated waste catalyst is periodically replaced with new one or re-generated by the manufacturer or used as for improving the soil conditioner, so that the catalyst consumption cost and final amount of bury can be minimized.

[77] As shown in FIG. 4, waste water formed from the Neutralizing- Washing Tower and

Active Carbon Producing Unit are treated for recover heavy metal, complex salt and usable water by means of the system which consists of Waste Water Holding Tank, Reaction Tank, Sedimentation Unit where the heavy metal is recovered, Evaporation- Concentration Unit, Dryer Unit where the complex salt is recovered as dry flake, and Condensing Unit where usable water produced and the non-condensible gas is sent to the Thermal Decomposer or to the Reformer.

[78] More in detail, the waste water hold in the Holding Tank is fed firstly to the Reaction

Tank where the remained heavy metal ion & some of other ion of impurities are formed to coagulation by the chemicals added, and is sent to

[79] Sedimentation Tank. The turbid water fed to Sedimentation Unit where the concentrated sediments including most of heavy metals as metal hydroxide form are recovered from bottom, and the light water from the top is fed to Evaporation-Concentration Unit where the most of the water is vaporized and the solute (Complex salt) are concentrated. The concentrated solute mostly consists of complex salt, is dried at Dryer Unit and recovered as Dry Complex Salt (mostly NaCl). The water vapor is condensed at Condensing Unit where the usable industrial water is recovered and the non-condensible gas discharged to Thermal Decomposer (SlO) for decompose any possible pollutants contained.

[80] Since, most of the pollutants, such as dioxin and heavy metals, are already removed at Dust Collector (S40) by the absorption effect of carbon and the dioxin shall be decomposed (decomposed dioxin), heavy metals are recovered at Active Carbon Producing Unit, therefore the final waste water treating is able to be easily performed.

[81] As the results of above processing, non-combustibles (ash) included in waste are recycled into metal & aggregate by thru the pre-separation & melting, and combustibles are recycled into clean fuel gas by thru the thermal decomposition, reforming, & few step of purification.

[82] Hereinafter, a process for producing and processing secondary and third products by utilizing clean fuel gas will be explained with reference to the sixth step S60 of FIG. 2.

[83] Firstly, the secondary product shall be selected at least one or more within the category of steam or hot water generation by gas boiler, electric power generation by gas engine or combined cycle (gas turbine + steam turbine) power generator, specific chemical product such as Hydrogen, Ammonia, Methanol, Dimethyl Ether, Ammonia, Urea Fertilizer and Ethanol etc. by corresponding each chemical processing system according to given conditions and circumstances.

[84] Secondly the third product shall be oxygen fist due to self usage and any suitable products from secondary products.

[85] More in details, the processing systems for producing secondary and third product may be applicable to the conventional technology and devices. The typical processing system for producing electrical power and oxygen are shown in the Figs 5 and 6.

[86] Referring to Fig. 5, the electrical power is producing with gas engine or combined cycle power generating unit by utilizing the primary product of clean fuel gas in which the heating value of fuel gas should be considered adequately. The generated electrical power is utilized firstly for the own process as moving power, heating and for oxygen producing system, and the surplus shall be sent to outside for 100% utilization. The electrical power generation system, in which the power generation thermal efficiency by gas engine is around 25-32%, and by combined cycle is around 40-48% is known normally.

[87] Referring to Fig. 6, the oxygen rich gas is produced with VPSA Unit (Vacuum pressure swing absorbent) which well-known existing technology by utilizing the secondary product of electrical power and air. This system consists of Air Blower for feeding air, Two Columns (molecular sieve packed) for separating oxygen from air, Vacuum Pump for desorbing nitrogen and venting from the absorbent in the column and Compressor for sending out the produced oxygen. The purity of produced oxygen is around 92-93% is known normally.

[88] When the clean fuel gas is combusted by using air at a final stage of usage, the flue gas does not violate a pollution relating law without being later processed, only if combustion conditions satisfy the conventional conditions for clean fuel gas such as town gas and LPG.

[89] The present invention may implement an integrated process comprising with the main process for producing clean fuel gas as primary product, an active carbon producing process for producing active carbon by using collected carbon, a waste water treating process for processing waste water produced from each process, an oxygen producing process for producing oxygen, and any of other process for producing a third product. As the integrated system is implemented, total energy using efficiency and reduction of total installation cost is improved significantly compared to the case when each system is separately installed and operated.

[90] In the present invention, the heat required for thermal decomposition and reforming for producing fuel gas from waste are supplied by partial combustion heat of the waste with oxygen, in other word, part of the waste is utilized as source of heat supply and a part of remained waste is utilized as source of feed stock for producing fuel gas, by direct contacting the hot combustion fluid to the wastes for thermal decomposing in the Thermal Decomposer Furnace, therefore this mechanism may be achievable the highest thermal efficiency & cheaper operating cost compared to indirect heating and using outside heat sources.

[91] In the present invention, when apply optimized operational conditions at Reformer, make results of lowering operation cost and minimizing the amount of harmful pollutants in final disposal. Firstly, the outlet temperature of the Reformer maintained in between 95O⁰C- 1050⁰C by control the amount of oxygen feeding, The higher temperature directly influences on the higher oxygen consumption and reducing fuel gas production, and the lower temperature make opposite results to above, but too lower temperature may results to operational interruptions at subsequent processing due to heavy hydrocarbons, specially tar components. Secondly, the amount of steam feeding to the Reformer shall be maintained in between 1-1.5 times of stoichiometric amount. The higher steam feeding shall reduce the content of heavy hydrocarbons in discharge gas but increase operation cost, while the lower steam feeding shall increase the content of heavy hydrocarbons. Thirdly, the retention time (reaction time) of the gas stream for passing thru the Reformer maintained in between 4-6 seconds by control feed rate of waste, for achieve all of above purposes. The overall preferable control target is to maintain at the disappearing point of tar component and make sooty carbon content still remain in the discharge gas stream. The sooty carbon remained in the gas stream functions very effectively for absorbing harmful dioxin and heavy metal until the gas stream passing thru the Dust collector, therefore the amount of harmful components remained in the final disposal shall be minimized.

[92] Furthermore, in the present invention, the purpose of installing the Ash Pre-treatment

Unit is to give two functions. First is for give easy operability at the Melting Furnace according to reducing heat load & melting time by crushing the ash, adding flux for lowering the melting point at the Ash Pre-treatment Unit, and complete combustion of combustibles remained in ash and pre-heating the ash at the Roasting Furnace before feeding to the Melting Furnace. Second is for give operational flexibility, in other word, operational independency in between the two categories of the processing system, one is the processing system from the Thermal Decomposer up-to final clean fuel gas product producing system, and another is from the Roasting Furnace up-to melted slag producing system thru the Melting Furnace.

[93] It will also be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

[1] A method for recovering resource from waste, comprising: a first step for decomposing waste into ash and reformed gas by performing a partial combustion, a thermal decomposition, and a reforming process; a second step for pre-processing the ash obtained in the first step; a third step for recycling the ash pre-processed in the second step into resource by a melting process; a fourth step for recovering sensible heat of the reformed gas obtained in the first step, and separating sooty carbon from the reformed gas by a dust collecting process thereby recycling into active carbon and heavy metal ; and a fifth step for purifying the reformed gas having undergone a dust removing process in the fourth step into clean fuel gas, and performing a recycling operation.

[2] The method of claim 1, further comprising a sixth step for producing at least one of power, steam, oxygen, and petroleum chemical products by using the clean fuel gas produced in the fifth step.

[3] The method of claim 1, wherein the first step comprises: obtaining ash and thermally-decomposed gas by performing a partial combustion and a thermal decomposition in a Thermal Decomposer; and obtaining reformed gas by reforming the thermally-decomposed gas in a Reformer so as to perform an additional thermal-decomposition.

[4] The method of claim 3, wherein in the reforming step, an operating temperature of 95O⁰C- 1050⁰C, a reacting time of 4-6 seconds, an injection amount of steam for acceleration of a thermal decomposition corresponding to 1-1.5 times of stoichiometric amount are used as optimized operating conditions.

[5] The method of claim 1, wherein in the second step, a metallic material is separated from the ash, the ash is crushed, and a flux is added thereby to lower a melting point at an Ash Pre-treatment Unit.

[6] The method of claim 1, wherein the third step comprises: completely combusting a remaining unburned component by firing the ash obtained in the second step at Roasting Furnace; melting the roasted ash at a Melting Furnace; and cooling the melted ash in a Quench Water Bath thereby making into aggregate.

[7] The method of claim 1, wherein the fourth step comprises: recovering sensible heat from the reformed gas by Waste Heat Boiler; further lowering a temperature of the reformed gas having undergone a Temperature Control Apparatus, separating co-generated carbon from the reformed gas by a Dust Collector, and collecting the carbon; and producing active carbon by an Active Carbon Producing Unit with using the collected carbon, by separating heavy metal and waste water.

[8] The method of claim 1, wherein the fifth step comprises: cooling, neutralizing-washing the reformed gas having been carbon-removed in the fourth step at a Quenching Tower and Neutralizing- Washing Tower; boosting the neutralized washed gas at a Boosting Blower; desulfurizing the boosted gas at a Desulfulizer having a catalyst therein; and discharging produced waste water to the Waste Water Treatment Unit, and thereby separating usable water, complex salt and heavy metal from the waste water.

[9] The method of claim 8, wherein in the step of cooling, neutralizing-washing, the gas is firstly cooled to 60°C~80°C at a Quenching Tower by spray & fogging water, and the acid gas is secondly neutralized by washing with alkaline solution, simultaneously the surplus water vapor and heavy metal vapor are condensed, dust remained also is absorbed into water phase and cooled down to 4O⁰C at the Neutralizing- Washing Tower, then the gas is sent to a Boosting Blower and the waste water is sent to the Waste Water Treatment Unit.

[10] The method of claim 2, wherein oxygen produced in the sixth step is used in at the first to third steps.

[11] A resource recovery system, comprising: a Thermal Decomposer for thermally decomposing fed waste into ash and thermally-decomposed gas; a Reforming Furnace connected to the Thermal Decomposer, for reforming the thermally-decomposed gas produced from the Thermal Decomposer thereby exhausting the reformed gas; a Waste Heat Recovery Boiler connected to the Reforming Furnace, for recovering a sensible heat of the reformed gas and generating steam; a Temperature Control Apparatus connected to the Waste Heat Recovery Boiler, for lowering the temperature of the gas from Waste Heat Recovery Boiler; a Dust Collector connected to the Temperature Control Apparatus, for removing carbon from the gas thus collecting, and exhausting the gas having been carbon- removed; an Active Carbon Producing Unit connected to the Dust Collector, for producing active carbon by using the carbon collected by the Dust Collector, and separating heavy metal and waste water therefrom; a Quenching-Neutralizing- Washing Tower connected to the Dust Collector, for quenching, neutralizing and washing the carbon-removed gas; a Boosting Blower connected to the Quenching-Neutralizing-Washing tower, for boosting the neutralized and washed carbon-removed gas; a Desulfurizing Tower connected to the Booster, for desulfurizing the boosted carbon-removed & acid free gas by using a catalyst; a Reservoir for storing clean fuel gas come from the Desulfurizing Tower; an Ash Pre-treatment Unit connected to the Thermal Decomposer for preprocessing the ash formed from waste; a Roasting Furnace connected to the Ash Pre-treatment Unit for roasting the ash; a Melting Furnace connected to the Roasting Furnace for melting the roasted ash; and a Quench Water Bath connected to the Melting Furnace for cooling the melted ash thereby making into aggregate.

[12] The system of claim 11, further comprising at least one or more of: a Gas Engine Power Generating Unit by using clean fuel gas. a Gas Boiler for generating steam; an Oxygen Generating Unit for generating oxygen; and a Various Chemical Conversion Unit for producing petroleum chemical products.