Waste to Energy Steam Boilers

Municipal solid waste or MSW is also called trash or garbage. It is generated from households, educational institutions, commercial establishments, community, and recreational activities. The composition of MSW varies depending on the municipality. Some cities in the country have well-defined segregation and recycle system.  MSW is a mixture of energy-rich materials such as paper, cardboard, plastic, rubber, plant waste, and wood.

Urban India produces 62 million tons of garbage every year. This is expected to increase by 5% every year because of the increase in population and changing lifestyle. The megacities of India such as Ahmadabad, Bangalore, Chennai, Delhi, Kolkata, and Mumbai have high economic growth and generate tremendous quantities of waste. Only 42 million tons of waste is collected, approximately 11.9 MT of waste is treated and approximately 31 MT of waste in landfills. Experts believe India has flawed waste disposal and management system.

Landfills cause odor, increase greenhouse gas emissions, cause problems to animals and plants, and are a fire hazard. Waste to energy steam boilers can help reduce the pressure on landfills.

Characteristics Of MSW And RDF

The composition of municipal solid waste (MSW) can be classified into:-

  • Organic 50% (Kitchen waste, Agro-waste, Vegetable waste, Garden waste)
  • Recyclable 20% (plastic, paper, syringe, tin, tablets, metals, glass)
  • Inert 22%(Sand, pebble, gravel)
  • Others 5%

The biodegradable content was analyzed for its physicochemical characteristics such as proximate analysis (moisture, volatile matter, carbon, and ash). The average moisture content of MSW is 34.1%. The large moisture content is mainly due to moisture in vegetable and food waste. Quantity of metal is negligible since most of it is recycled. The vegetable waste with high moisture quantity and low GCV can be turned into manure.

Type of Waste

Moisture (%)

Volatile Matter (%)

Ash (%)

Carbon (%)

Vegetable

61.17

2.35

28.23

8.23

Paper

28.17

14.28

42.85

14.28

Cloth

21.42

28.57

14.28

35.71

Plastic

37.5

25

0

37.5

Others

22.05

1.47

73.52

2.94

 

The Ultimate Analysis and energy content was        

Type of Waste

C

H

O

N

S

Ash

Energy (KJ/kg)

Vegetable

9.73

1.29

7.62

0.52

0.08

1.01

496.852

Paper

2.49

0.33

2.55

0.14

0.02

0.34

1038.326

Cloth

1.09

0.14

0.9

0.06

0.009

0.14

1237.432

Plastic

1.13

0.13

0.43

0.04

0.007

0.18

4689.216

Others

7.02

0.84

2.66

0.3

0.04

1.76

469.852

 

The average waste material used for waste to energy process is composed of materials that increase the calorific value of the waste. The waste stream or refuse derived fuel (RDF) is made up of paper, cardboard, cloth, plastic, and wood.  The average heat value of RDF is 26.67 MJ/kg.  The MSW needs to be processed before RDF is formed.

Magnets and mechanical screening are used to remove non-combustible material such as glass and metal. An air knife is used to separate the material. The light material with higher heat value is used to create RDF while the heavier material is sent to landfill. 

RDF is prepared in the MBT plant (mechanical and biological treatment plant) according to the limits set by the boiler manual. The fuel parameters for the fuel are:

Parameter

Value

Moisture Content

Between 20-45%

Metal content

Upto 2%w

Ash Content

Between 15 to 30%

Chlorine content

Up to1%w

Fluorine content

Up to 0.2%w

Nitrogen content

Up to 1%w

Sulfur content

Up to 0.3%w

Calorific value

Between 10 to 14 MJ/Kg

 

Challenges Of RDF:

  • RDF contains high quantities of alkali (potassium and sodium oxide), which lowers the ash fusion temperature.
  • The silica along with the alkali content causes fouling on the heating surface areas.
  • Silica and fly-ash can cause erosion.
  • High chlorine content can cause corrosion.

Advantages Of RDF

RDF has been used to generate over 7.5 MW in India. The advantages of using RDF as fuel are:-

  • Reduction in large quantities of solid waste from landfills. 
  • The fuel has a calorific value ranging from 10 to 14 MJ/Kg (2390.06-3346.08 kcal/kg) which is equivalent to many biomass fuels.
  • RDF is a low-cost fuel that is readily available.
  • RDF has better emission characteristics compared to coal. The fuel contains a negligible amount of Sulfur and has low quantities of nitrogen.
  • Recovers recyclable material such as tin.

Features Of RDF Boiler

Waste to energy boilers are vulnerable to corrosion.  The fuel characteristics limit the furnace temperature to below 850oC and superheater temperature to below 400oC. Mago Thermal Private Limited has carefully designed waste to Energy steam boiler keeping the unique fuel characteristics in mind.

  • The boiler has a specially designed water-cooled reciprocating grate that can handle a range of fuels.
  • The tall membrane-wall furnace design helps to reduce the furnace exit temperature and increase the residence time.
  • The 3 pass boiler helps to utilize maximum heat from the flue gas.
  • Strategically located soot blowers can minimize fouling.
  • The flue gas can be treated in our air pollution control equipment before being released through the stack.

Why Choose Mago Thermal?

Mago Thermal Private Limited (MTPL) has been designing, supplying, erecting, and commissioning boilers for over 20 years.  Our experience in burning biomass and fossil fuel has helped us tackle the RDF boilers successfully. MTPL provides a 360 solution for power solutions. We offer:-

  • Stand-alone boilers
  • Cogeneration boilers
  • EPC solutions

Mago Thermal is a leading provider of air pollution control equipment to ensure your boiler complies with the statutory emission norms in India. The equipment is designed by professional and experienced engineers.

CONTACT US FOR A FREE TECHNICAL EVALUATION OF YOUR UNIT