Technology of Combustible Waste Sorting and RDF Manufacturing Facilities in

Sudokwon Landfill

Yong Gun Lee, Sang Pyung Kim, Jung Hyun Park, Choon Taek Jeon, Jang Taeck Kim, Sang Hee Lee and Hwa Soo Oh; SLC

CONTACT Yong Gun Lee Sudokwon Landfill Site Management Corporation (SLC) #58, Baekseok-dong, Seo-gu, Incheon, South Korea TEL : +82-32-560-9548, FAX : +82-32-560-9555 E-mail : yglee@slc.or.kr EXECUTIVE SUMMARY The household waste carried into Sudokwon (Metropolitan area in South Korea) landfill site is composed with 94% combustible and 6% incombustible. Eco-friendly mechanical pre-treatment of waste and RDF (Refuse Derived Fuel) manufacturing plant (200ton/day) is installed for making energy from combustible household waste. As the percentage of the water content of actual intake waste is exceed the deign standard, the system had been overloaded. The trouble has been solved by the addition of air mixing facility and the renovation of the combustion chamber. INTRODUCTION As the paradigm of Korean national waste management policy has been changed from reduction, reuse and safe disposal into resource circulation ‘Zero Waste’ society, Sudokwon Landfill Site Management Cooperation (SLC) started the RDF manufacturing project for minimizing the amount of reclamation and maximizing resource reuse, getting out of simple reclamation. For treating whole amount of municipal waste carried into Sudokwon landfill site, SLC have a plan to construct a RDF manufacturing 2,200ton/day scale plant until 2014. Prior to install the plant, the demonstration plant has been built from November 2007 to April 2010 included 8months test operation. This study shows the problems and improvements during test operation.

GENERAL INFORMATION OF SUDOKWON LANDFILL SITE The purpose of construction of Sudokwon landfill site is for treating waste, converting it into resource and contributing to create pleasant life environment of local residences. Total area is 19,790,000m2; the area of waste landfill is 16,000,000m2 and the area of environmental research complex and other facilities is 3,790,000m2, and total volume of the landfill is 228,000,000tons. The reclamation of waste has been started from 1992 and it is possible for utilizing 34years from now on. The reclamation period would be extended due to waste to energy project. SLC is also operating a leachate treatment facility and a 50MW landfill gas power plant.

Figure 1. The Facilities Statue of SUDOKWON Landfill Site

RDF MANUFACTURING DEMONSTRATION FACILITY The general situation and the physical-chemical characteristics of intake waste SLC reclaimed whole amounts of intake waste (4,445,000tons) produced from 58 cities of Seoul, Incheon and Gyunggi in 2009; household waste 792,000tons (17.8%), construction waste 1,527,000tons (34.4%), and business waste 2,126,000tons (47.8%) was taken. Daily average amounts of intake waste are about 3,000tons. Table 1. The Quantity of Intake Waste in 2009

(Unit : 1,000ton) Total Municipal Waste Construction Waste Domestic Waste

4,445 (100%)

792 (17.8%)

1,527 (34.4%)

2,126 (47.8%)

Table 2 shows the physical characteristics of household waste carried into Sudokwon landfill site in 2009; the percentage of combustibles is 90% (paper 45.8%, plastic 22.3%, and food 11.4%) and the percentage of incombustibles is 10%. Table 2. The Physical Characteristics of Household Waste in 2009

(Unit : %, Wet Weight Basis)

Combustibles Incombustibles

Paper Plastic Food Textile Wood Etc. Total Glass Metal Etc. Total

45.8 22.3 11.4 3.9 1.4 5.2 90.0 2.1 1.8 6.1 10.0 Three contents of household waste carried into Sudokwon landfill site are combustible 68.0%, Moisture 21.6%, and ash 10.4% in 2009 respectively. Caloric values are Dry basis high caloric value (Hho) 4,950kcal/kg, damp basis high caloric value (Hh) 4,003kcal/kg, and damp basis low caloric value (HL) 3,528kcal/kg each. Table 3. Three Contents & Caloric Value of Municipal Waste in 2009

(Unit : kcal/kg) Three Contents Caloric Value

Moisture Combustible Ash Hho Hh HL

21.6% 68.0% 10.4% 4,950 4,003 3,528 The Outline and Main Facilities of RDF Manufacturing Demonstration Plant The combustible materials of household waste (200ton/day) carried into Sudokwon landfill site are made into RDF by crushing and sorting in RDF manufacturing demonstration plant invested total 23milion dollars approximately. The construction of this plant was started in November 2009 and completed in April 2010 include 8months test operation (July 2009 ~ March 2010). This plant is located on ‘Waste-to-Energy Town’ in Sudokwon landfill site of Incheon city and the area is 9,600m2

. This plant is composed of 200ton/day pretreatment facility and 100ton/day RDF manufacturing facility. Major facilities are intake-feed facility, mechanical pretreatment facility, dryer, pelletizer and dry exhaust gas treatment facility.

Figure 2. The Layout of RDF Manufacturing Demonstration Plant

A stand-by crusher for constant feeding was applied to the intake-feed facility, so continuous operating became possible without stopping. The reservoir of faulty waste and inappropriate material was secured and the fully spacious feeding entrance was installed in the facility. The intake waste is sorted by three steps (<100mm, 100~300mm, >300mm) according to organic material size to minimize the loss of combustibles going through the mechanical pretreatment process. The vibrate screen and the disk screen were installed for improving the combustible material collection and food waste sorting. The wind separator was installed for separating the light material and heavy material and improving the chloride-contained material sorting. The NIR optic separator was also introduced for removal of incombustible and chloride-contained materials at once. Maximum 30.9% of water contents before drying makes lower than 10% after going through the dryer by rev count control in the inverter. Fuel consuming reduction effect has been achieved through the exhaust gas circulation by the installation of a heat exchanger. Six pelletizers (2ton/hr each) include one reserve enable continuous operation without stopping.

Figure 3. The Process Flow in RDF Manufacturing Demonstration Plant

PROBLEMS OCCURED DURING TEST OPERATION AND SOLUTIONS Problems in Operating Although the percentage of water content of the waste had been designed as 40% at intake step and 30.9% at the front of dryer (the end of crusher) on the lowest grade basis, the percentage of the water content of actual intake waste represented maximum 51.2% according to seasonal factors (intake of wet waste such as fallen leaves, vegetables). It caused overloading to the dryer, and then normal operation was impossible. As the apparent density was increased due to intake high moist waste, the separation efficiency of specific gravity was declined and the loss of combustibles was increased when the organic was separated. As high moist waste was also working as an Interruption factor of the constant operation of belt conveyor and pelletizer at the end of dryer, pelletized RDF was crumbled because of unsatisfying with the standard which is lower than 10% standard of the percentage of the water content and bad pelletizing. According to the intake of the sorted inappropriate materials such as fabric and iron, the production rate of RDF was fallen and the continuous operation was interrupted. The major improvement For solving the problems by seasonal variation, the dryer has been improved for being able to treat smoothly however high moist waste may be received. The heat capacity of

the dryer was increased from 2million kcal/hr to 2.5milion kcal/hr for improving drying efficiency. Preventing fire and explosion by high temperature operation, the oxygen concentration analyzer inside the dryer and the explosion proof hole upper the dryer were installed and the waste slot conveyor was also sealed to control oxygen inflow. As the additional air mixing system was installed, combustion efficiency has been increased through the sufficient mixing. Extending retention time and keeping a proper heating load by renovating the combustion chamber shape, incomplete combustion factor also reduced. The collection cone of cyclone was expanded and the screw conveyor was installed to minimize the loss of combustible material. The conveyor type was changed from belt to chain or apron for keeping the slope as 25̊ and the scraper was introduced to prevent a waste jam on the conveyor. As the vibrating screen type was also changed form vibration motor to crankshaft for coping actively with the changing bulky density, the vibration cycle and speed could be controlled easily. A vibration roller was installed in the wind separator to increase the separation efficiency and prevent the accumulation on the latter part of the system. CONCLUSION The percentage of the water content of household waste carried into Sudokwon landfill site was known as annual average 20% and maximum 40%, but it showed more than 50% during test operation because of seasonal factor. It should be fully considered to the dryer design on future project. This project would extend the life-cycle of landfill sites by converting waste materials into resources, thereby minimizing the negative effects of dumping waste. Furthermore, it would also contribute to satisfy the demand for transition from a society based on resource-consumption and growth to a zero-waste, resource-circulation society. REFERENCES SLC (2007): Basic Design Report of Combustible Waste to Resource Demonstration Project, pp. 10 – 22. MOPAS, MIFAFF, MKE, MOE, MLTM & KFS (2008): Waste and Biomass Energy Measure, pp. 12 – 15. Lim, H. S., Lee, Y. S., & Kim, Y. H. (2009): Grading Distribution and Physical·Chemical Properties of Waste Carried into Sudokwon Landfill, 2009 Study Compilation of Green Technology Research Center NO.6, pp. 19 – 27.

SLC (2010): SUDOKWON landfill statistics yearbook NO.8 SLC (2010): Test Operation Report of Combustible Waste to Resource Demonstration Plant