ECOVE's Fluidized Bed Incinerator Operated at Full Capacity for Five Consecutive Years

Fluidized beds have the advantage of uniformly incinerating waste with high water content, low heat value or complicated composition through high heat capacity bed material. As they are easy to operate at lower loading and can start up and shut down quickly, they are widely applied in waste incineration, biomass fuel combustion or co-firing. 

ECOVE operates the Tainan Science Park Resource Recycling Center (hereinafter referred to as "the Center") and treats more than 90 types of waste which involves complicated physical and chemical characteristics and high variation in volume. The fluidized incinerator was therefore selected as the core heat treatment facility. There has been no unscheduled shutdown since it began commercial operations in May 2003. It became a reference for successful technical applications of fluidized bed incinerator in Taiwan.

Fluidized Bed Incinerators - Uniform Fuel Mixing and with High Efficiency

The bed material, particles, in a fluidized bed is forced by upwards fluid. When the fluid reaches minimum fluidization velocity, the bed material will be suspended and in a fluid-like state which is referred to as “fluidization”. Fluidized bed incinerators mix fuel uniformly and achieve uniform temperature distribution, high contact area, high heat capacity, and fast heat transfer and mass transfer. They are therefore widely used in commercial operations.

According to the flow behavior of be material (detailed in Figure 1), there are two main types of fluidized bed, namely the bubbling fluidized bed (BFB) and circulating fluidized bed (CFB). The main difference in characteristic is shown in Table 1 and each type of fluidized bed has its own advantages and disadvantages. Therefore the type of fluidized bed to apply is case by case and must be practiced based on actual conditions and the waste type.

Figure 1. Diagram of flow behavior in bubbling fluidized bed (left) and circulating fluidized bed (right).

CTCI Group Selects Incinerator Based on the Characteristic of Waste

ECOVE’s parent company CTCI Group considered the 90+ types of waste in Tainan Science Park when it took over the turn-key transfer project for the construction of the Center. The waste includes biomedical waste, solid waste, sludge, and waste solvents, etc. 

The different types of waste materials have different feed methods and great variation in heat value, which required rigorous consideration and adoption of more effective treatment mechanisms.

The advantages of fluidized bed incinerators are listed in Table 2. For instance, fluidized bed incinerators have fewer rotating parts than rotary kiln incinerators. The cost of maintenance and repairs are low and the fluidized bed provides better heat insulation and high boiler efficiency. For sludge treatment, both fluidized bed incinerators and rotary kiln incinerators are able to fully mix sludge ,which  mechanical grate incinerators cannot achieve. In terms of environmental protection, fluidized bed incinerators generate less nitrogen oxides (NOx) than other types of incinerators and they also effectively reduce the production of dioxin. All these advantages make the fluidized bed incinerators the best choice for the Center.

Furthermore, CTCI Group considered the instability and variations in waste production from the sources when the Center was first established and selected the economic “bubbling” fluidized bed as the core technology for the incinerator because it can treat multiple types of waste simultaneously and it is easy to start up and shut down.

ECOVE Develops Patented Technologies to Resolve Operational Issues in Fluidized Bed Incinerator

ECOVE generally faces three major difficulties in the operations of the fluidized bed incinerator at the Center:

• Control and management of non-combustible waste
Non-combustible waste such as glass liquidizes under temperatures in the incinerator and wraps around the bed material. When the amount of glass is high, it causes “defluidization” and the incinerator must be shut down to clear the agglomeration. In response to this challenge, ECOVE  adopted measures to control and manage waste from preliminary review, entry inspections, and vehicle inspections to learn about the status of non-combustible waste. The Center adopts appropriate measures to treat non-combustible waste and prevent its entry into the incinerator to reduce risks.

• Mixing waste with different heat values
As different types of waste have wide range in heat values, they may cause the incinerator to overheat and cause clinker if the total heat values of waste are not properly controlled. They may also cause the temperature sensor to be covered by clinker and reduce the accuracy of temperature detection, thereby causing wrong total heat value estimation in mixing waste. ECOVE uses high heat value feed proportion adjustments and distributed input of combustible materials to achieve desired control levels.

• Improvement of feed systems for different types of waste
ECOVE has more than 20 years of experience in the operations and revamping of incineration plants. The company has redesigned, modified, and optimized the feed system, resolved stability issues for the feed system of solid waste and liquid waste, and applied patents for the unique technologies developed. The company has fully demonstrated its considerable research and development capacity as well as technical capacity.

ECOVE has extensive experience from the selection of incinerator types appropriate for the waste to special designs for the feed system that satisfies multiple simultaneous feeds and abundant experience in waste management. Under the management of ECOVE, the Center processes 27,400 metric tons of waste for the Industrial Park each year. It has operated for five years at full capacity without any “unscheduled downtime” and all operations are normal.

Based on verification in actual operations, the Center’s combustion efficiency (CE) exceeded 99% and the destruction and removal efficiency (DRE) of hazardous organic substances that contain chlorine exceeded 99.99%. The automatic control system and feed system are highly reliable and overall operations have been great. ECOVE also effectively reduced dioxin, NOx, and CO concentration in the exhaust and uses the most environmentally friendly methods for waste resources recycling.

Performance of ECOVE's Fluidized Bed Incinerator

ECOVE has extensive experience from the selection of incinerator types appropriate for the waste to special designs for the feed system that satisfies multiple simultaneous feeds and abundant experience in waste management. Under the management of ECOVE , the Center treats 27,400 metric tons of waste for the Industrial Park each year. It has operated for five years at full capacity without any “unscheduled downtime” and operations  well all the time.

Based on verification in actual operations, the Center’s combustion efficiency (CE) exceeded 99% and the destruction and removal efficiency (DRE) of hazardous organic substances that contain chlorine exceeds 99.99%. The automatic control system and feed system are highly reliable and overall operations have been great. ECOVE  also effectively reduced dioxin, NOx, and CO concentration in the exhaust gas and uses the most environmental-friendly methods for waste resources recycling.

Treatment of industrial waste requires the selection of suitable treatment facilities based on the categories and characteristics of the waste as well as the selection of “professional and reliable” waste treatment institutions. CTCI Group provides “turn-key” construction services that include design, planning, procurement, contracting, and construction management of the incinerator and selects incinerator models based on the requirements of enterprises and waste and specific local conditions to improve resource recycling efficiency.

ECOVE  has achieved successful operation of incinerators from the introduction of the Total Solution described in Unit 1, maintenance of the industrial economy and environmental sustainability in the operations of the Center described in Unit 2, to the actual operations of the fluidized bed incinerators described herein. The series of achievements have demonstrated that ECOVE has sufficient technical capabilities to assist the governments and enterprises of all countries in resolving difficulties in treating waste and improving waste treatment efficiency.