Thesis Yi Chenqi Industrial Management Accepted

Thesis Yi Chenqi Industrial Management Accepted
The Research and Development of Garbage Burning Power
Thesis
Yi Chenqi
Industrial Management
Accepted
s
SAVONIA UNIVERSITY OF APPLIED SCIENCES, BUSINESS AND ENGINEERING, VARKAUS
Degree Programme
Industrial Management
Author
Yi Chenqi
Title of Project
The Research and Development of Garbage Burning Power
Type of project
Date
Pages
Final Project
14.02.2011.
50+5
Supervisor of study
Executive organisation
Harry Heikura
SUAS, Varkaus
Abstract
The aim of the thesis is to introduce the application and development of garbage burning power, so
that the reader can understand better the process of garbage burning power technology, and carry out
the garbage treatment issues in theory and practice.
The thesis focuses on garbage treatment and research equipment of garbage burning power. Through
the analyzes and comparisons of different types of incinerators, it was found that the CFBI
(circulation fluidized bed incinerator) and rotary kiln incinerator are the mainly used equipment in
garbage burning power.
The specific structure and operation process of CFBI and rotary kiln
incinerator are described in the main chapters. Some key systems and techniques were researched in
this process, and technical details in the entire process and application were analyzed.
As a result, the garbage burning power technology is the best way to treat waste in humans’ normal
life. However, this technology has both disadvantages and advantages, such as: the pollution control
issues cannot be ignored. Therefore, the de-dioxin system has been created to minimize pollution; the
application and working process of this system are represented in the thesis. To generate the power
and to dispose of the waste with low pollutants in the same time is a decisive factor in the feasibility
analysis of the garbage burning power technology in the future.
Keywords
MSW, Garbage Power, CFBI, Kiln Rotary Incinerator, Dioxin, Pollution Control, BOT Method
Confidentiality
Public
Table of Contents
ABBEREVIATIONS
3
1 INTRODUCTION
5
2 THE BASIC PROPERTIES OF GARBAGE
8
2.1 The Current Situation of Municipal Solid Waste
8
2.2 The Composition and Characteristics of Municipal Waste
10
2.3 Integrated Treatment of Waste
11
2.4 The Recycling Method of Energy in Waste
16
3 THE DEVELOPMENT OF GARBAGE POWER TECHNOLOGY
17
3.1 The Development in Foreign Countries
17
3.2 Garbage Power and Environmental Protection
18
3.2.1 Orientation of Garbage Treatment
19
3.2.2 Introduction of Burning Equipment
20
4 GARBAGE BURNING POWER TECHNOLOGY
21
4.1 Technological Process of Garbage Burning Power
21
4.2 Post-Processing of Garbage Incineration
23
4.3 Technology of Fluidized Bed Combustion
25
4.4 Garbage Burning Power Equipment
27
4.4.1 Grate Furnace Incinerator
27
4.4.2 Rotary Kiln Incinerator
28
4.4.3 Circulating Fluidized Bed Incinerator
30
4.4.4 Gasification-melting Incinerator
31
5 POLLUTANT CONTROL IN GARBAGE POWER
32
5.1 Generation and Control of Dioxin
32
5.2 The De-dioxin System
33
5.3 The Control & Treatment of Secondary Pollutant
35
5.4 Emission Standard
39
6 RESULTS
41
7 DEVELOPMENT PROSPECTS OF GARBAGE POWER
43
7.1 BOT Method for a Factory
43
7.2 Strategies of Garbage Power Development
44
8 CONCLUSIONS
46
REFERENCES
48
APPENDICES
Appendix 1
Appendix 2
Appendix 3
Appendix 4
Appendix 5
ABBEREVIATIONS
MSW
Municipal Solid Waste
GDP
Gross Domestic Product
UNEP
United Nations Environment Program
RDF
Refuse Derived Fuel
CFBI
Circulated Fluidized Bed Incinerator
FBC
Fluidized Bed Combustion
PCB
Printed Circuit Board
PLC
Programmable Logic Controller
BOT
Build-Operate-Transfer
BOOT
Build-Operate-Owner-Transfer
5
1 INTRODUCTION
Municipal solid waste is the main environment problem all over the world that needs to
be faced at present. Municipal waste is increasing gradually every year. Improper
handling of garbage causes great harm to the environment: land occupation,
contaminated soil, contaminated groundwater resources, impact on air quality, polluting
the atmosphere, spreading diseases, environmental health and the health of residents.
Sound waste disposal and effective management of waste disposal has become a serious
problem in many cities.
The relatively common garbage treating methods are sanitary landfill, incineration, and
utilization (such as the produce of organic fertilizers, building materials, heating and
power generation, etc.). Municipal solid waste burning is a high temperature
thermo-chemical treatment technology; the waste goes into the combustion chamber as
solid fuel, in 800 ~ 1000
high temperature conditions, garbage and combustible
components react with oxygen from the air. When there is enough waste heat value, the
garbage can maintained its own spontaneous energy, rather than to provide
supplementary fuel. In waste combustion temperature combustion gas can be recycled
as heating, stable residue can be disposed of directly to landfill. After incineration,
waste of bacteria, viruses and a variety of malodorous gases can be eliminated by
high-temperature decomposition. [B1]
Garbage burning treatment has its own exclusive advantages: [B1]
Good in volume reduction. Garbage burning could reduce 80 ~90% of the volume of
the waste;
Thorough disinfection. Garbage in the high temperature combustion can be
completely broken down to harmful ingredients, and can completely kill the
pathogens, especially combustible carcinogens, viruses, contaminants, toxic organic
6
compounds;
Follow-up to reduce or eliminate the environmental impact of disposal process. It
also can significantly reduce pollutants in landfill leachate concentration and the
release of the combustible gases and odor components;
MSW conducive to the resource. High temperature incineration flue gas, the heat
absorbed by the waste heat boiler into steam, which can be used to heating or power
generation.
Processing efficiency. Incineration plants occupy small areas of land and are close to
urban areas. This could save space and reduce the transport distance of waste for the
economic development of the city. This is particularly important.
Based on these advantages, the realization of garbage incineration, reduction and
recycling is one of the most effective means of waste disposal in the future.
The purpose of the thesis is to reveal the basic research and development of waste to
energy program, and to introduce the garbage burning power. Overall, the thesis is
divided into three parts: theory, research and conclusions.
It the theory part, the basic properties of garbage is introduced first. It contains the
current situation and the composition of MSW. Secondly, development of garbage
power technology and then garbage burning power technology are presented. In these
two parts, I will make the comparison between a foreign country and China. Also the
integrate treatment of waste is introduced.
In the research part, we will do the experiment to measure how much energy we can get
from burning waste is carried out. Some data to certificate the efficiency of garbage
power is given. Another point is to present the pollution control in garbage burning. The
environmental protection is the theme nowadays all over the world. We cannot ignore this
main point when we are developing our industry.
7
The last part is conclusions. This part states the development prospects of garbage power.
This will make garbage power popular when population and MSW increase. This will
bring benefits for all over the world. In the end of this part, I will also give some advice
for garbage power development.
Garbage as a new renewable energy, besides of others like wind, solar, nuclear and
water, should be paid attention to. With increasing population, the MSW is also growing
gradually. Some places cannot be lived in because they are filled with trash and waste. It
is not only influencing the environment, but it also brings hazards to human’s normal
life. Striving to develop garbage power is the best way to improve the living
environment and global environmental protection issues.
8
2 THE BASIC PROPERTIES OF GARBAGE
Waste is produced by humans in daily life. With the developing of economy, the
municipal waste grows every year.
2.1 The Current Situation of Municipal Solid Waste
From a global perspective, there is 1.0×1010t of waste discharged all over the world per
year currently. The United States is the most trash producing country with over 2×108t
per year; Germany produces about 800kg of waste per person. However, in the UK the
waste produced by person everyday just increased to 0.27kg from the year 1971 to 1990.
In contrast, the waste has reached 1.2 × 108t of waste per day in Tokyo Japan. [B1]
In China, according to the development of national economy and increase of population,
the industrial waste and household garbage are accumulated more and more. The
situation of environment becomes more serious, some cities surrounded by wastes have
become a challenge to the government. The statistical sources revealed that every
citizen produced 400kg of waste and main cities produced 1.5×109t in average annually.
Nowadays, the domestic garbage storage volume has reached 6.0×109t and occupied a
land area of about 5×108m2 with an annual increasing rate of about 8%~10%. At present,
there are 200 cities surrounded by garbage among the whole cities. This has brought up
a series of serious social problems, which caused huge pecuniary losses. Solely in
emission and sewage, they caused 4%~ 8% GDP losses directly. The danger of the
municipal refuse not merely embodies in taking up too many lands; it forms the
abominable environment where rubbish surrounds the city. It will also cause pollution in
the atmospheric environment, underground sources of water, soil and crops. The
organism from the waste is deteriorated and the harmful gas goes into atmosphere to
pollute the environment, which affects the normal life and health of citizens. Otherwise,
9
the organic matter content is higher in the municipal waste, rubbish produces methane
after fermentation, the main ingredients are CH4 and CO2, both of them will impede the
growth of vegetation and destruct the ozone layer. Even more, the CH 4 is a flammable
gas and when it mixes with air in certain proportion and meets the sparks, it will
explode. Because of garbage also has lots of pathogens, parasitic ova and other factors
to harm the health of humans, it will influence the humans’ environment and cause the
spreading of diseases. [B1]
Table 2.1 Proportion of waste treatment methods in different foreign countries [B1]
Country
Landfill %
Compost %
Burning %
America
75
5
10
Japan
23
4.2
72.8
UK
88
1
11
France
40
22
38
Netherlands
45
4
51
Denmark
18
12
70
Australia
62
11
24
Recently, there are three garbage treatment ways: sanitary landfills, compost and
burning, which is aimed at reduction, decontamination and waste resourcization in
garbage treatment. In the year of 2002, there were 740 garbage treatment factories for
different kinds of rubbish among 664 cities in China. It could dispose of 7835×108t in
one year that has been improved from 2% in the 1980s to 58.2% today. [B1]
10
2.2 The Composition and Characteristics of Municipal Waste
The composition and characteristics of municipal waste depend on the life quality,
habits of life, season and refuse classification or any other factors in different regions. In
European developed countries, because of different habits and customs the composition
of waste has great differences. Same as in China, municipal waste has different moisture
content in different season.
Table 2.2 The composition of garbage in different cities in China [B1]
Combustible %
Region
Food
Paper
Noncombustible %
Plastic
Dust
Metal
Glass
waste
Heating
Capaci
moisture
value
ty
content
(kJ/kg)
(t/m3)
/%
Beijing
32.60
15.10
14.60
21.46
1.96
0.402
53.90
Shanghai
42.22
1.80
0.60
55.31
1.07
0.898
37.00
Guangzhou
36.35
1.32
1.26
57.43
3.64
0.543
30.00
Shenyang
34.96
2.11
1.74
58.14
3.05
0.640
44.12
Chongqing
41.61
1.59
0.74
52.68
3.48
0.600
45.00
Xi’an
38.24
3.80
1.20
55.66
1.10
0.556
29.00
Shenzhen
56.41
12.90
11.16
19.53
19.53
Suzhou
58.30
7.91
7.17
19.63
19.63
Ningbo
47.51
8.287
15.47
20.44
20.44
Jinan
32.68
2.37
0.61
70.45
1.90
5000
43.63
1.68
4370
53.63
3.867
3977
51.00
0.370
13.00
China is a developing country and its’ economy is also under development. The
following characteristics of municipal waste are compared with foreign developed
countries:
1. Complicated ingredients. Most cities in China use a mixed collection method to
11
collect waste, but there is no classification. So many kinds of wastes are mixed together.
2. High moisture content. There are too many peels of fruits and vegetables, so the
moisture content is about 30%~50%.
3. High inorganic substance content. At present, most cities in China using coal as the
main fuel. It contains slack, sandstone, metal and glass from the waste, which have a
high inorganic substance content.
4. Low organic substance content. In organic matter, there is a lot of food trash, which
has high moisture content. However, paper, plastic, wood, leather and textile fabrics
these kind of high heating value matters are lower.
With the improvement of living standards and popularity of using gas in the normal life,
the organic matter and heating value in municipal waste has increased a lot. For
example, in Beijing the waste heating value has increased from 3349kJ/kg to 5862 kJ/kg
from the end of 1990s to the 21st century.
2.3 Integrated Treatment of Waste
Basically, the main waste treatment method has been divided into two categories, which
is marine disposal and continental disposal. The marine disposal refers to ocean
dumping and ocean burning. The continental disposal contains landfill, compost,
burning and integrated treatment. Because of the high costs of marine disposal and this
method produces a lot of secondary pollutants, so it is now rarely used. But the
continental disposal is widely used.
Landfill method is filling the waste into a pit or sunken pool, which also benefits the
recovery of the landscape and keeps ecology in balance. However, the disadvantage of
this method is that it occupies too much land (1t waste needs 3m2 of land), or even the
secondary pollution, such as: underground water polluting, noxious gas scattered in the
12
air and the filled waste ferment to produce methane that easing causes explosion. In
1996, the EU environmental protection council made a rule that the garbage without
treatment is forbidden to be land filled directly. [B2]
Composting treatment method is a way to transmit the municipal waste to outskirt
village to be used as a fertilizer. This method is good for improving soil and of low cost,
large handling capacity; but without classification. Then a lot of trash had been wasted,
which could have been used as other resources. At the same time, such as glass, metal,
plastic could not be used as fertilized waste because they cause secondary pollutants to
the environment. Therefore, this method is only used in small scale and in France,
Sweden, and the Netherlands only accounts for 1.3%~1.5% of handling capacity. [B2]
The aim of the burning method is to reduce the volume and mass of the waste. In some
countries like Japan, Denmark, Sweden and so on, because of limited in land area
resources, burned waste has became the main method of municipal waste treatment. The
advantage of this method is to reduce the filling waste efficiently, after burning only 10%
of the initial volume waste needs to be taken to the landfill and also the energy could be
recycled; parts of leavings after burning could be used again. Otherwise, burning
method costs so much. According to UNEP provision, the waste is suited for burning
treatment when the heating value is between 3350~7100kJ/kg. Furthermore, if the
garbage treatment devices are not good in quality or make noxious gas during burning,
it is forbidden to use this method.
The following are the advantages of garbage integrated treatment: [B2]
1. Reduction of waste. The integrated treatment method can use 90.6% of the
ingredients of waste; only 9.4% needs to be land filled. If burning directly, 86% of the
waste can be reduced and the rest of 14% put into landfill.
2. Generating capacity. Most of moisture content and noncombustible material need
absorb heat when burning directly. So, using 35% RDF of waste as fuel could make
13
more heating power than 100% burning.
3. The address of electric power plant. It is chosen around the city or dwelling district
that can be able to exert the advantage of combined heat and power generation
together thoroughly.
4. The hearth of boiler volume. Because of the boiler in integrated treatment electric
power plant only burns the RDF (Refuse Derived Fuel), so the volume of hearth has
1/3 of a normal incinerator. Then the other accessories also correspond to smaller
than normal one, the cost of incinerator can greatly be reduced.
5. Discharge amount. Generally, the direct burning waste is more than integrated
treatment waste, so the rate of discharge amount in exhaust is 1.8:1. In accordance
with same environmental requirements terms to treat exhaust, the actual emissions
of direct burning were doubled compared to integrated treatment.
6. Aggregate investment and operating maintenance cost. The data reveals that the rate
of aggregate investment and operating maintenance between direct burning and
integrated treatment is 1.15:1 and 1.55:1 respectively.
14
Table 2.3 Comparisons of several garbage treatment programs
Items
Sanitary landfill
Direct burning
Integrate
Integrate burning
treatment
Program
Waste landfill,
Direct
introduction
sewage disposal
power plant
Process flow
burning
Sorting of refuse,
Improve incinerator
composting
to use run coal and
and biogas
RDF
collection system
factory
and
burning
RDF as mixed fuel
Remote of living
Heating value must
Stable
area,
meet requirements,
heating value and
of
exhaust
easy
value through the
laying
treatment
biogas
and
export
disposal
device complicated
RDF
exhaust
disposal device
safely
Low
requirements
RDF
heating
run coal to adjust
stability
Reduction rate of
Almost
no
86%
waste
reduction
Environmental
Affects the
Causes
influence
surface water and
exhaust
underground
50%
water
evaporates
90.6%
90.6%
huge
The real emission
The real emission
emission,
only have 60% of
only have 50% of
burning
burning
of
water
to
the
atmosphere
Aggregate
About 30 million
Disposal of 1200t
Disposal of 1200t
Disposal of 1200t
investment
Euros
waste, 80 million
waste, 55 million
waste, 9.4 million
Euros
Euros
Euros
15
Items
Sanitary landfill
Direct burning
Integrate
Integrate burning
treatment
Operating cost
and
The expenses are
The expenses are
About
transportation of
6% of investment
6% of investment
Euros per year
waste,
cost annually
cost annually
Collection
sewage
3
million
disposal costs
Income situation
No-direct
Waste
metal
incomes
recycling
Compost,
waste
metal recycling
Compost,
supply
heat, waste metal
recycling
Integrate
Because of capital
Huge
evaluation
had
and
investment
Low
investment
Besides the
complicated
and pollution. The
advantage of
treatment
garbage resources
integrated treatment,
are
utilized
even reduces the
thoroughly. This is
investment costs
cannot be solved,
the
of
from improvement
so this
foreign
garbage
of old power plant.
been
invested,
the
exhaust
influence
of
process.
sewage
has
abandoned
leaking
method
been
by
direction
treatment
Makes the best
development.
benefits of garbage
European
resources utilization
countries.
by combined heat
and power
generation.
16
2.4 The Recycling Method of Energy in Waste
The use of MSW energy was popularized in the 1960s. The basic ways are burning
power, marsh gas generation, thermal-decomposition and the use of waste plastic to
make oil.
Garbage burning process resembles to normal industrial burning process. When
analyzing in the fuel aspects, the combustive matters in fuel could be released and
utilized in burning process. But the burning efficiency cannot be 100%, so all the waste
energy could not be used when the garbage is burned. [B2]
The marsh gas is produced by landfill waste disassemble. Only the resolvable waste can
be used when produce energy in marsh gas form produced. It also cannot be resolved
100%, so the landfill waste energy cannot be used in marsh gas form totally.
The biggest difference between thermal-decomposition and burning process is the
nonsufficient oxygen supply. So it would be harder in burning process, even if the same
mechanism the energy was used the efficiency may be lower than in garbage burning
Obviously, using waste plastic to make oil only used the plastic without any other
ingredients. So it can only use the energy from plastic in all waste.
17
3 THE DEVELOPMENT OF GARBAGE POWER TECHNOLOGY
The use of garbage burning to make steam and electricity could be traced to time a
hundred years ago.
3.1 The Development in Foreign Countries
The first solid waste burning power equipment was built in Germany in 1895. In 1905 a
garbage burning power plant was established in New York. Until 1950, the garbage
burning equipment consisted of a fire resisting incinerator and heating recycle boiler.
Some developed foreign countries have developed garbage burning technology to solve
the MSW pollution problem earlier. Most of them have some typical technology, such
as: Germany, Martin boiler technology, the USA, Foster Wheeler fluidized bed
technology and Japan, IHI rotary kiln technology.
In recent years, using MSW burning power and heating supply has been developed fast
in a large scale. In Paris, 90% MSW supplies heat to the entire city through four garbage
burning factories. In the USA and Germany, the government supports and promotes the
development of garbage power. They have built many garbage power plants for the
production of electricity and disposal of MSW.
In Finland, the government has improved MSW disposal methods continuously in the
past 20 years, from the pour and landfill to recycling and classification of waste. To
recycle and classify the disposal of MSW efficiently, it is not only good for maintaining
the environment, also good for trash to treasure. In each residential area and shopping
center, there are several different waste recycling dustbins in different colors. All the
waste can be collected into a recycling point. Then the waste is sent to different places
which have been classified clearly. Such as: metal waste sent to metal disposal factory,
18
waste woo is sent to power plant as fuel and batteries, medicines, waste oils are sent to a
burning factory, which could use the burning heat to make electricity. Even though all
kinds of MSW is classified and recycled, still a lot of mixed garbage is poured into
waste landfill. In order to reduce the poured waste, the garbage treatment center built a
mixed garbage disposal factory in 2005. Then it could classify remain waste and deliver
the unrenewable waste to landfill again. In this method not only landfill area was
reduced sharply, there were not odors to pollute the air by biological waste separation.
Moreover, mixed garbage disposal factory produces 2.0×103t of combustible refuse
every year, that could make 6.0×105kW·b of power instantly. [B1]
Japanese development of MSW burning power technology is fast. There are 131
garbage power plants in Japan, which have 420MW of power to make electricity. The
burning treatment rate occupies 84% of the whole MSW. Otherwise, Japanese have
good habits to classify garbage; the government’s policy is aimed to minimizing,
recycling and safe treatment of MSW. [B1]
There are almost 300 garbage burning incinerators in France which can dispose of 40%
MSW. Based on the classification of treatment system statistics, there are 5.2% MSW
renewable, 74.6% could be fuel to make electricity, 18.7% cam be reacted and filled in
landfills and 1.5% can be stacked. Large benefits can be reached and the residents must
pay the waste disposal tax based on their living area. [B1]
3.2 Garbage Power and Environmental Protection
With the rapid growth of economy and development in cities, the pollution is also
increasing all the time. This problem is always ignored when a country is dedicated to
industrial development when a mass of waste is stacked, it easily spreads diseases,
polluting the environment and is unsightly. How to dispose of MSW in scientific
processing is an urgent problem which needs to be solved in modern cities nowadays.
19
3.2.1 Orientation of Garbage Treatment
Basically, the treatment of garbage is divided into three kinds of methods: landfill,
compost and burning method. These are also the three accepted standard methods for
garbage treatment.
Landfill treatment is the most basic method that is easy to use and has a large handling
capacity. But it occupies too much land and the land is limited nowadays. Otherwise, in
the process of landfill, a lot of waste is exposed in the air, which provokes the breeding
of many pests. Then pesticide has to be sprayed to avoid secondary pollution and high
costs. [W1]
Composting is using the organic matters in waste to achieve the utilization of recycling
and also reduction of water. Meanwhile, it could reduce the capacity of nonrenewable
waste and landfill costs. However, the same as landfill treatment, compost also needs
quite a large area to process. Some wastes also need to be classified and that increases
the costs of composting. Although compost treatment achieves the goals of waste
reduction, recycling and safe treatment in some parts, not thoroughly. It must be
integrated with other methods like burning or landfill. [B1]
Burning treatment is the delivery of the MSW to a burning power plant; it reduces the
volume of the waste, mass and the need of decontamination. After burning, the volume
of wastes could be reduced by 90% and the mass by 75%. The heat made by burning
can be used to make electricity; the combustion efficiency is 85% and thermal
efficiency above 50%. The main problem in garbage burning is that the exhaust gases
cannot always stay within the set limit. Western developed countries have strict garbage
emission management standards, especially in smoke treatment and exhaust emission. A
bag-type dust remover is used which has 99% dust abatement efficiency; spray CaO2 to
absorb SO2, HCL, and HF; it uses active carbon to absorb dioxin and so on. Garbage
20
burning treatment must be integrated with landfill, when after burning 10% of the
remained waste should be filled in landfills. Then the landfill volume is reduced without
pollution, also costs decline. [W1]
3.2.2 Introduction of Burning Equipment
Grate incinerator is used in nonrenewable heating power garbage, which has low
operating costs and reduces large volume of waste. If the waste has a low moisture
content, high heating value (above 8374kJ/kg) and few nonflammable matters, the
incinerator will burn steadily. It is also easy to ensure the vapor pressure, temperature,
flow rate. Because western developed countries have these features and a good standard
of living, good quality of waste, most of the garbage power plants use this incinerator.
[W2]
CFBI is circulating fluidized bed incinerator, which is used in burning special waste or
rubber and bark. The use of CFBI is a trend to develop MSW burning technology in the
future years. The features of CFBI: large applicable scope, use lot coal to support
combustion, low requirements for MSW and burning the MSW when the heating value
is above 3349kJ/kg in theory. [B1]
Overall, grate incinerator is not suited for MSW burning at present; however CFBI has
good adaptive capacity for many kind of waste. The price of the combustion supporting
coal is 1/20~1/7 price of coal. Then makes it more competitive to those heat and power
combined generations which is using coal for thermoelectric plant to support
combustion in CFBI. It is also good for market-oriented management and development
of wastes treatment.
21
4 GARBAGE BURNING POWER TECHNOLOGY
There is a hundred of years of history of garbage burning power. The heat input of
garbage burning power is using the incinerator burning to transmit heat to water, and
then the water turns into steam and go through the steam turbine to drive a dynamo
generate electricity or support heat directly. Basically, the technological process of
garbage burning power is divided into non-sortation and sortation garbage power.
4.1 Technological Process of Garbage Burning Power
Generally, there are two main ways for garbage burning power: non-sortation garbage
power and sortation garbage power. Actually, these two methods are quite similar, the
only differences are in the beginning of the process.
Non-Sortation garbage power
The delivered waste is poured into a designed cesspit that could store 3~4d quantity of
refuse. After microbial fermentation and dehydration, the crane puts the waste into the
hopper of incinerator. In the bottom of the hopper, there is a parts feeder that delivers
the waste into incinerator continuously. However, the moisture content of waste is high,
and then it needs burner aid to put some oil or coal to support combustion before it
starts burning. Once it starts burning it, the preheated ventilator works making the steam
get hot and delivers into the bottom of the grate to ensure the adequately combustion of
the waste. In addition, the entrance of ventilator connecting with wastes, so the waste
gases in cesspit can be delivered into 800~900
incinerator to thermal decomposition.
Then the smokes go through the exhaust purifier, bag-type dust remover and vent to the
chimney. The burnout clinkers are dropped into refuse vessel and delivered on travelling
22
belt after cooling down. There is an electromagnet on the belt which attracts those
metals in clinkers to recycle. At last, these ashes and clinkers can be integrated to
treatment or land fill.
Graphic 4.1 Technological process of non-sortation garbage power
23
Sortation garbage power
The differences of technological process between non-sortation and sortation are
recycling and clean no-combustion before burning. Then they have the same working
process in the following stages.
Graphic 4.2 Technological process of sortation garbage power
4.2 Post-Processing of Garbage Incineration
There are exact demands for garbage burning after-treatment. Not only the inside
temperature of the incinerator must be above 850
and the duration more than 2s to
reduce pollutants, but the exhaust treatment is also very important which contains dust,
toxic organochloride, SO2, NO2 and CO. Generally, a semidry process is used to clean
up the poisonous gases in the smoke and active carbon is used to absorb dioxin, and
24
then they go through a bag-type dust remover to the filter. After a series of processes, it
can meet the environmental protection standards easily. [B1]
The solid slag should be reduced instantly after waste burning and metals should be
recycled. Otherwise, the slag and dust are collected by a dust collector which could be
separated in different collecting, storing and delivery ways. Different kinds of waste
need to be disposed of in different ways, for instance, slag to garbage; fly ash to
hazardous waste; solid waste exhausted by gas cleaning unit must be discerned if it is
dangerous waste before it is disposed of. [B1]
Table 4.1 The requirements for the height of garbage incinerator chimney
Quantity of waste(t/d)
The
lowest
allowed
<100
100~300
>300
25
40
60
height(/m)
Note: t/d = ton per day
The height of chimney refers to the assessment of environmental impact. In addition,
the chimney must be 3m higher than all the buildings in 200m distance at least.
Moreover, if there are any garbage burning plants consisting of several types of
incinerators, the chimney must be set as a single discharge cylinder or multi-discharge
cylinder. The chimney and flue should be according to international standards, which set
the permanent hatch and install sample detection platform.
25
4.3 Technology of Fluidized Bed Combustion
Technology of fluidized combustion is the most common method to the disposal of
refuse. At present, the amount of emission is over 1.0×1010t all over the world annually.
The development of fluidized combustion technology is a new technology for waste
burning. It also creates a new area for environmental protection.
At present, most foreign countries prefer to use mechanical grate combustion. The
drying and combustion area is in the front of the furnace, where the high moisture and
low heating value waste was reacted in the high temperature radiation condition, so it is
easy to make them dry and fired in advance. Hence, a temperature area for waste
combustion is established.
The grate combustion technology is suitable for high heating value waste. Because of
high life standard in European countries, MSW could combust directly even without
classification that the Qdw is over 8378kJ/kg. However, RDF heating value is much
higher after classification, for instance in Finland, it is about 25958kJ/kg. Nevertheless,
due to the low combustion efficient and unique manufacturing technology of grate
system, this causes high costs and high maintenance fees. Otherwise, to make sure the
boiler achieves the needed technological parameters in combustion, the fuel and high
operating cost should be added. So the application of grate combustion technology is
limited. [B2]
Fluidized bed combustion is a combustion technology used in power plants. A fluidized
bed suspends solid fuels on upward-blowing jets of air during the combustion process.
The result is a turbulent mixing of gas and solids. The tumbling action, which is much
like a bubbling fluid, provides more effective chemical reactions and heat transfer. FBC
plants are more flexible than conventional plants in that they can be fired on coal and
biomass, among other fuels. [W3]
26
There are two reasons for the rapid growth of FBC technology. At first, the liberty of
choice in respect of fuels in general, not only the possibility of using fuels which are
difficult to burn by using other technologies, which is essential for fluidized bed
combustion. Furthermore, which has become increasingly important, is the possibility
of achieving, during combustion, a low emission of nitric oxides and the possibility of
removing sulfur in a simple manner by using limestone as bed material.
Graphic 4.3 The process of circulating fluidized combustion [W4]
FBC developed from efforts to research a combustion process that is able to control
pollutant emissions without external emission controls, for instance, scrubbers-flue gas
desulfurization. This technology burns fuel at temperatures of 1,400-1,700°F
(750-900°C), good control under the threshold where nitrogen oxides form, at
approximately 2,500°F / 1,400°C, the nitrogen and oxygen atoms in the combustion air
combine to form nitrogen oxide pollutants; it also avoids the ash melting problems
related to high combustion temperature. The mixing action of the sulfur-absorbing
chemical would contact with flue gases which are brought by fluidized bed, such as
27
limestone or dolomite. More than 95% of the sulfur pollutants can be captured inside
the boiler by the sorbent. [W3]
4.4 Garbage Burning Power Equipment
Garbage incinerator is the main equipment for garbage burning power, which is divided
into grate furnace, rotary kiln incinerator, circulating fluidized bed incinerator and
gasification-melting incinerator. [W4]
4.4.1 Grate Furnace Incinerator
The principle of grate furnace incinerator is sending the waste to the conveyor. With the
movement of the conveyor, the waste is dried and fired in the forepart of the conveyor
in the high temperature condition. The waste is combusted thoroughly with oxidizing air
reaction, then pernicious gases from the wastes could be decomposed and combusted in
the high temperature smoke. The inside temperature is almost above 850
, to avoid
unburned combustible produces odious smell out of chimney. Therefore, it needs fuel
support combustion when the waste has a low heating value. High temperature flue gas
cools down through the boiler, using a draught fan to suck acid gas. Then a bag-type
dust collector removes dust in the waste. After a series of process, the flue gas exhaust
to air from chimney. [B3]
The main features of grate furnace incinerator:
1. Using of different kinds of wastes as fuel that are easy to operate
2. The system has good reliability and stability.
3. Keeping combustion gaseity in high temperature and retention period in furnace, to
reduce the emission of pernicious gases.
28
Graphic 4.4 Grate incinerator for MSW burning [W5]
4.4.2 Rotary Kiln Incinerator
The rotary kiln incinerator is manufactured with a rotating combustion chamber that
keeps the waste moving, so that allowing it to vaporize for burning. It is widely used in
several types of wastes. For example: [W5]
PCB waste and hazardous waste
The waste used in medical or clinical like “Red bag waste”, injection needles,
rubber gloves and tubing, blood plasma remains, laboratory waste, steel tools, glass
pipette, etc.
Sludge waste, cattle waste, industrial waste, petrochemical waste, etc.
29
Graphic 4.5 Operating system of rotary kiln incinerator [W5]
The system depends on the amount of chlorine in the waste steam, there is another dry
cleaning system used for the flue gas treatment. Generally, there are two combustion
chambers in the whole system. They all have a drive motor and a gear box inside of
secondary combustion chamber, which with support burner has 1300
degrees and a
residence time of 2 seconds per minute. In the whole system working process, there is
an energy recuperation system that
donated units for active carbon and
Sodium-Bi-Carbonate to the flue gas in the drying scrubbing system, HCl, SO2
scrubbers and dioxins were removed from the system. The continuous emission
monitoring system with all instrumentation and controls that control panels with
programmed PLC to control the installation. By the way, the supporting fuel burner for
the combusting chamber and the de-ashing chamber at the end of the rotary kiln. [W5]
The main characteristics of rotary kiln:
1. Has great resistance to high temperature
2. It can handle liquid, gas, solid and sludge in large amount
3. Operating temperature from 800-1300 degree
4. It can batch modes like barrels and allows more flexibility than continuous modes
30
4.4.3 Circulating Fluidized Bed Incinerator
The circulating fluidized bed furnace consists of a combustion chamber, a cyclone and a
loop seal. The combustion air blows silica sand and fluidizing medium upward from the
bottom of the riser to the top of the riser. The gas velocity inside of the riser is as high as
4-6m/sec and the air is in a turbulent state. In the riser, sludge and screen surplus are
dried and burned rapidly, turning into fine ash except the incombustibles. The
combustion ash is delivered to the cyclone with the silica sand. Because of the
differences in specific gravity and particle size, the sand and the ash are separated,
which is sent to the flue gas treating unit with the exhaust gas, the sand falls into the
loop seal then is returned to furnace. [W6]
Graphic 4.6 System flow of circulating fluidized bed incinerator [W6]
The main features of CFBI:
1. It is easy to adjust the amount of circulating particles by controlling the primary air.
It prevents local temperature drop or balloon.
2. There are no such limitations of CFB furnace because the temperature inside furnace
is easy to control.
31
3. It is widely used in sewage treatment and sludge, filtration surplus treatment.
4. The required static pressure of the fluidizing blower is so low that it consumes less
power. It only needs 15-25kPa of circulating type compared with bubbling fluidized
bed (25-30kPa).
5. Compared with the bubbling fluidized bed in air speed of 1m/sec, the CFB gets
4-6m/sec, which is good to halve the inside diameter of the furnace.
6. The medium intensifies contact, mixing and blending of air, raising the combustion
efficiency and enabling low air ratio combustion.
7. The heat taken back by the circulating particles that help to dry sludge, the
preventing temperature drop in the lower part of the furnace and without auxiliary
fuel.
Consequently, the CFB combustion can be applied to coal in a high fixed carbon content
and sewage sludge with high water content. The CFB technology may be applicable to
burn a variety of fuels and waste since then that as a means of effectively and efficiently
utilizing energy, the one will become increasingly diversified. For sewage sludge
treatment in particular, the technology has the potential to reach mixed combustion with
screenings, grit or other types of wastes, including energy recovery. [W6]
4.4.4 Gasification-melting Incinerator
Gasification-melting incinerator uses high temperature melted iron as fuel which has
1400
degrees. The MSW is melted and gasified rapidly when thrown into the furnace.
With thermal decomposition and burning, the gas was exhausted from the traditional
incinerator. Moreover, residue would be ejected as grainy within fluid that is a kind of
new model incinerator in low secondary pollution. However, the gasification-melting
incinerator is still under development. So it is not as widely used as several types of
incinerators mentioned above.
32
5 POLLUTANT CONTROL IN GARBAGE POWER
In MSW burning process, the limitation of dioxin is the main problem concerned all
over the world. This kind of super-class toxic gas would affect the environment
seriously. The production and diffusion of dioxin should be controlled effectively it
influences the application of garbage burning and garbage power directly.
5.1 Generation and Control of Dioxin
Dioxin is a general term for a group of elements that in super-class toxic, but it is
categorized by its isomeride. The most poisonous substances are 2.3.7.8-PCDD, which
almost like 1000 folds of KCN (potassium cyanide). The dioxin exists as a gas and in a
solid form, it has a high melting point, immiscible solvent to water, but it easily
dissolves to fat and accumulates in vivo. It should be limited in garbage burning
treatment strictly.
Besides of normal garbage burning would produce dioxin, incomplete combustion also
makes that happen. When there is not enough oxygen during the combustion process,
then precursor of dioxin is produced. Those precursors, chloride in waste and oxygen
generate dioxin substances by complicated thermal reaction. In another way, the
precursor and cyclic hydrocarbon will response with chloride and O2 under the catalyze
of Cu, Ni, Fe these kind of metallic particle in smoke around 300
reaction
temperature. [B4]
A proper polluted material for incineration is the best available way to prevent and
control exposure to dioxins, which can also destroy the waste oil based on PCB
(polychlorinated biphenyl). The incineration process requires high temperatures of over
33
850
to destroy large amounts of contaminated material, or even a higher temperature
is required. [W6]
In addition, the use of a new model bag-type dust remover is necessary, controlling the
smoke temperature under 200
beside entrance of dust remover. A spray unit like
activated carbon in the funnel of dust remover to absorb dioxin is set. Choosing of an
advanced control system in garbage burning plant is also necessary to accomplish
burning and refine waste effectively.
5.2 The De-dioxin System
The de-dioxin system is a system that preprocesses the waste before burning. It
combines manual and mechanical devices to classify waste. It aims at picking out
recyclable waste like metal, glass or plastic; and the waste cannot be burned such as
dust, bricks or stones that are used in building materials or landfill. The preprocessing of
wastes is good to improve the combustion efficiency and operation stability. However,
the most important thing is reducing the PVC (polyvinyl chloride) in waste and also
decreasing the source of chloride that easily produces dioxin.
34
Graphic 5.1 The flow of de-dioxin system
As we can see from the flow chart, the MSW went into rotary screen through by
garbage hopper and A belt. Then it went to B belt, after manual classification that parts
of waste can be recycled or landfilled, others enter a waste crasher. Then they pass to C
belt as the required size, in the end of C belt there is a magnetic separator that sucks
metals from waste. Finally, all the waste is sent to incineration after this series of
processing. Some of waste goes to another branch apart from A belt. It meets vibrator,
which extracts the dust or organics for landfill and composting. The remaining waste
then goes to the C belt where it merges together with the trash out from the crasher in
incinerator as the same process. [B4]
Another successful de-dioxin system is for CFBI, a tail gas cleanup unit has been set
with bag-type dust remover together. The basic principle is using alkaline compound to
absorb acidic gas, meanwhile the porous media will also absorb little of dioxin organic
pollutant and heavy metal. A bag-type dust remover is adopted to archive gas and solid
intensely segregated. Further trace amounts of dioxin are absorbed through the surface
of filler material media to prevent dioxin diffusion. [B4]
35
This system is aimed at reducing the emission of dioxin through tail gas cleanup. The
smoke produced by burning is accelerated through zoom nozzle, and then it enters the
CFB cleanup unit that uses denitrification and porous absorbent as bed materials. After
chemical reaction the bed material is fluidized with smoke and it reacts with acidic
gases; the dioxin is absorbed by remover, heavy metal and fly ash fine particle are
disposed by the cleanup unit. The products produced from reaction leave in peeling
agent in solid form, mixed with not completely reacted bed material, and then they go to
the gas-solid separator. The solid particle goes into buffer tank, but most of solid
particles mix with absorbent go in a mixer and are then recycled using a CFB
purification reaction device. Redundant matters in buffer tank exhaust from flash gate.
Purged smoke goes out from chimney through a dust remover exit. [B4]
5.3 The Control & Treatment of Secondary Pollutant
Most of waste produces secondary pollutant after incineration, like dioxin, heavy metal,
toxic gas and dust. Those pollutants affect the environment as solid or gas, but tail gas is
the one of the most serious pollutant in environment pollution. Therefore, there are
several methods below to reduce secondary pollution effectively.
Controlling contaminant sources
First of all, the waste should be classified and recovery should be enhanced, the
component with high chlorine like PVC or metal catalyst needs to be dislodged.
Secondly, to make sure leak tightness of garbage warehouse that blower pumping is
used inside of warehouse under the negative pressure environment, and then all the
gases are delivered into incineration to support combustion. Thirdly, moisture content in
waste should be collected in a sewage pit and pumped into furnace burning scission.
[B4]
36
Furnace combustion control
In aspect of pollution control, CFBI is a typical one that solves sufficient combustion
and contaminant deprivation problem. It uses quartz sand as thermal medium, in large
heat storage capacity, good burning stability and temperature uniformity between 850 ~
900
, low quotient excess air, produces a few NOx substances (only produced a large
amount over 1300
). At the same time, it also controls the production of dioxin
effectively. The conditions for dioxin generation are unstable combustion, temperature
in a furnace is lower than 700
and mixing is done with a catalytic agent. However, the
temperature in CFBI could be controlled above 850
, the coal is mixed up with fumes
that stay in furnace about 3 ~ 5s. This method is not only increasing combustion
stability, but also restraining dioxin with SO2 produced by coal burning. The limestone
is desulfurized effectively, when Ca/S is 1:2 the percentage of desulfurization is over
85%. There are 100% organic matters burned out in CFBI, 75% of waste and 90%
volume have been reduced. The ash is non-toxicity, odorless that could be land filled or
paved directly. Because of the reduction of 90% of waste to be land filled, it is also
good to extend the using time of landfill method. [B4]
Tail gas treatment technology
Fumes after burning have many kinds of toxic matters, using of regular desulfurization
technology cannot meet the emission standard. So integrated treatment technology
should be used.
1. Dust treatment
The equipment most widely used is electric dust collector and bag-type dust remover,
both of them could remove the fine fumes shorter than 1mm. Bur for heavy metals,
electric dust collector works worse than a bag-type dust remover, because of tail gases
37
enter into electric collector in high temperature that heavy metals could be not fully
condensed. By contrast, when the bag-type dust remover is combined with aeration
tower, the product of non-complete reaction Ca (OH)2 adhered on filter bag. To increase
the possibilities of surface contact with exhausted gas that improves the efficiency of
dislodged acid gases. Meanwhile, the operating temperature is under 250
that heavy
metals and chlorine organic compounds (PCDs/PCDFs) reach saturation then they are
condensed as fine granule sucked by filter cloth. Moreover, add some active charcoal
powder in front of remover’s air flue, which is good to adsorb heavy metal ion and
dioxin. [B4]
2. Acid gas treatment
The acid gases that exit in tail gases such as: SO2 and HCL. There are dry type,
semi-dry type and wet type cleaning methods. The cleaning principle is using CaO or
Ca (OH)2 react with acid gas in neutralization reaction, to produce CaSO4 or CaCl.
Dry type cleaning method is compressing the air then an insufflator is used to move
lime powder into flue reactor. Accordingly, the acid gases are neutralized and absorbed
from the exhaust gases. This kind of method is in low investment and low operation
costs but in huge medicine consumption and low working efficiency. [B4]
Wet type cleaning method is aimed at establishing a filler absorption tower. In the tower,
fumes convect with alkaline solutions; then it can react on surface and gap of filler that
absorbs the acid gases from the tail gases. The advantage of this method is high
exhausting efficiency. But it needs a lot of investments and sewage produced by
reaction needs to be disposed of. [B4]
Semi-dry type cleaning method consists of the features of dry type and wet type
methods; it consumes some lime and reduces the production of sewage. Because of
slurrying system is quite complicated that inner wall of tower is easy to bond with
38
seriflux and high power consumption of the nozzle. At present, there is a MHGT
(Multi-Constituents Hazardous Gas Treatment) technology based on semi-dry cleaning
method to dispose different kinds of exhaust gases. The principle of MHGT is using
CaO or Ca (OH)2 to absorb SO2, HCl, SO3 in tail gases, using high quality activated
carbon remove dioxin and heavy metals. Additionally, the slurrying system is canceled
within this technology. Not merely the leakage and stoppage problem are solved in
digestion, but also the steam is produced and enters into reactor to increase relative
humidity. The MHGT achieves the recycling of reaction several times and improves the
using of desulfurizer over 95%. The system takes small spaces and low operation costs,
the end products are used in pneumatic drive. Its high absorptivity is good to absorb
acid gas. The bag-type dust remover is combined with it that also has very good effect.
After professional testing, all the exhaust gases went through this system with low
emission loads. Especially dioxin discharged only 0.048mgTEQ/m3 that much lower
than 0.1mgTEQ/m3 as European emission standard. [B4]
39
5.4 Emission Standard
Escaped
Collection
b
Device
Collected
Feed
a
c
Figure 5.1 Basic collection device for formula
After the pollutant enters a collection device, there are two options: collected or escape
from the device, generally to be emitted to atmosphere. Then a simple mass balance has
been given:
Ma = Mb + Mc
(1)
Where Ma = amount of pollutant into collection device [kg/s]
Mb = amount of pollutant not collected [kg/s]
Mc = amount of pollutant collected, [kg/s]
With all measured in kg/s or equivalent units. [B5]
The efficiency,
of the collection device is the percentage of the total pollutant that is
collected, thus is relatively given by
Ef iciency:
= Mc/Ma
(2)
40
However, since Ma= Mb +Mc, so it can also written like
= Mc/(Mb + Mc)
(3)
In some circumstances if one might know, instead of the mass flow rates, the air flow
rates, Q (m3/s), and the concentration of the pollutants, C (kg/m3). Since M = Q * C,
given this information, the collection efficiency can also be calculated by either
= QcCc/(QaCa)
(4)
or
= Cc(Ca
Cb)
100/[Ca(Cc
Cb)]
(5)
The use of these formulas is determined by the information available that results are
identical. [B5]
There are many of collection devices that vary in their collection efficiency and the
nature of the pollutants. In general, the simpler, less energy-intensive devices are less
efficient, making them suitable primarily for large and dense molecules. Fine
particulates and other types of pollutants need more sophisticated collection devices.
[B5]
41
6 RESULTS
Garbage burning technology has been practiced as many years as a waste treatment
method. Compared with landfill method, it takes quite small land occupation and has
high working efficiency. With the development of the technology in Japan and Germany,
this industry has been popularized, many developed countries have been attracted to
imitate. Since then the garbage burning technology has been put into climax. However,
after hundreds of years practicing, this technology has not been accepted by most
people.
Disadvantages
The basic reasons for not accepting the method are: serious potential pollution, high
investment for this technology and resources wasted. Although the pollutant protection
technology is developing all the time, it is still not maturely enough.
As the data revealed, it produces about 5000m3 exhaust gases after one ton of waste had
been burned. After a part of pollutants are burned from the solid into gases, its weight
and the total volume is not reduced but increased. Incinerator discharges hundreds of
major pollutants; the composition of pollutants is extremely complex, it contains many
greenhouse gases and toxins. At present, the burning equipment in normal operation
condition, release dozens of harmful substances, which are and hard to absorb by
filtering, washing and cleaning. Especially the normal life has been influenced by
dioxins seriously.
Otherwise, huge investments and waste of resources were not suited for those
developing countries. The technology is still under developing stage and invested
money may not get valuable revenues. Moreover, the environmental protection program
should be considered itself.
42
Advantages
Although this under developing technology has many problems need to be solved, it
still has some benefits.
1. Simple process, operation reliability
No pre-sorting and waste can be directly burned. The industrial mode of production
can be impacted of natural conditions independently; the usage ages of incinerator
are over 20 years.
2. Waste disposal rapidly, high capacity
In operation process, because of several waste incineration plants treated large
numbers of waste, this has been set in their respective cities to create good social
benefits.
3. Reduction of waste
Reduction of 70% ~ 90% of waste, the increasing of garbage has been restrained
that is so important for land occupation limited countries.
4. In the high temperature incineration process, a large number of pathogens in the
waste are eliminated (it is particularly for the medical waste), improving the
sanitation of cities.
5. Using waste to generate the power, make waste profitable
43
7 DEVELOPMENT PROSPECTS OF GARBAGE POWER
With the developing of garbage power in recent decades, the technology has been
applied by many countries gradually. However, under the harsh economic circumstance,
for widely used and contributed to improve environment that still needs some policies
and regulatory leading.
7.1 BOT Method for a Factory
BOT (build-operate-transfer) method means that the government grants to the private
sector through contracts (including foreign state enterprises) for exclusive license in a
period, and allow it pay off the loan through the subscription fees or sell products,
recover the initial investment then make profits. The infrastructure transferred to the
government for free when the concession period expires. [W8]
Using BOT method to construct and operate municipal waste incineration power plant is
a very profitable program, local governments can remove the burden of investment and
running costs of municipal waste incineration facilities. Under the condition of
marketing economy, the construction and operation a corporation is relatively simple.
The costs are lower that provide very stable social funds and long-term returns of
investment. These funds play an important role to the national constructions and urban
environmental improvement. According to the technical and economic principles, the
establishment of large municipal garbage incineration power plant is in order to achieve
good social and economic benefits. In the specific principles to mobilize the initiative of
corporation, speed up the establishment of the municipal solid waste incineration
facilities. The better technical and economic performance process can be improved.
Otherwise, a part of research and development of high-tech equipment could improve
44
the technological level of mechanical and electrical manufacturing; if municipal waste
incineration power plants were constructed in many cities, the extensive using of
mechanical and electrical equipment, a lot of designs, installations and operation of the
personnel strength should be required, which can provide many jobs, laid-off pressure
of the local relief workers. [B6]
Nevertheless, some problems of this program exist in specific processing. In economy
aspect, to expect earn the money from waste disposal to reduce costs and increase
profits. Although there are many departments and local governments to promote the
implementation of waste disposal charges, refuse disposal fees received by authorities
much less than estimated value. This means the costs of waste disposal for building
municipal waste incineration power plants in BOT method also need to be sponsored by
government’s financial support. On the other hand, some areas still have to limit the
power generation of waste burning, the price departments jointly determine the price of
municipal waste generation; also in some places there is no internet access that payment
of it almost same with some heat-engine plants . In terms of oversight, there must be
unity, integrity, and improve of the norms with strict supervision. Therefore, use of BOT
method to construct an urban waste incineration power plant still needs to be considered
in more detail, which could make it more profitable. [B6]
7.2 Strategies of Garbage Power Development
Government investment in the construction, management and operation of the
environmental protection facilities have been gradually updated. Recently, the trends of
global issues are surrounded by garbage disposal socialization, marketization and
privatization.
In
the
future
evolution
for
the
use
of
BOT
and
BOOT
(build-operate-own-transfer) franchising model, that is based on sales of generated
electricity as revenue. The burning industry of municipal solid waste plays an active
45
role to promote technological advances in the development process. [B7]
Many countries all over the world have reached a consensus on global environmental
protection. In the current international economic situation, the environmental protection
industry has unique conditions in technology transfer, international assistance and
traders that more international multilateral and bilateral environmental assistance would
be attracted. [B8]
In recent years, waste from power generation technology development is gained
momentum in all aspects, to promote the waste for development of energy technology.
However, on whether the legal system or policy consummate, as well as create a
marketing circumstance that access to technical and financial assistance for both. There
are still many problems need to be further dedicated to improve development of garbage
power generation technology and human living environment.
46
8 CONCLUSIONS
Currently there are three methods used for waste disposal: sanitary landfill, composting
and incineration. Landfill is mainly used in some areas, but a lot of foundation treatment
is not good enough, it causes infiltration of groundwater and soil pollution. The
proportion of burning should be increased gradually, such as: construction of waste
incineration power generation projects, electricity and heat supporting. Through the
overall testing, the CFBI is the best recommended incinerator, which is based on grate
furnace technology.
Another important point is that garbage burning power is not only for generating energy,
but for garbage disposal and to prevent some regions add large amount of combustion
material to produce secondary pollution. Furthermore, especially in some places that
lack of land area also with high heating value, the corporations developed garbage
burning power technology in business ways that buy the spare lands from private owner
to release the pressure of land scarcity. Cogeneration was used in waste incineration or
landfill gas power generation, comprehensive utilization of resources; it has become an
important way to alleviate the financial burden of the government. But according to the
requirements of capacity, the number of some local waste incineration power plants is
increasing, which the way to plan and construct power plants completely against the
environmental protection rules. The principle of the phenomenon is making the future
management of waste disposal difficultly.
The fundamental purpose of waste disposal is a comprehensive treatment and
prevention of secondary pollution. To reduce waste and to convert waste into energy is
the obviously advantage of waste incineration power, but if in one-sided pursuit of
industrial waste generation and economic benefits, not only secondary pollution is
caused, this also affects the development of waste disposal industry seriously.
47
Waste incineration power plant should be based on waste-based fuels, the combustion of
the fuel mass fraction should be about 20%, and mixed waste with calorific value of
coal below a certain standard appropriately. It is so difficult to burn the waste with
different heating value with different mass fraction of waste. With the introduction of
the concept of the mixed heating value, it also applies to distinguish the power input of
the grate furnace after blending with supported fuel with the constant power output.
48
REFERENCES
Internet Sources
W1. Garbage Treatment
http://www.globalwarming360.net/garbage-treatment-plant.html
April 28, 2010
W2. Burning Equipment
http://kim-hi.51ev.com/product-Waste-Management/355987/Rubbish-Burning-Equ
ipment-waste-management-medical-incinerator-.html
May 2, 2010
W3. Fluidized Bed Combustion
http://www.patentstorm.us/patents/5401130.html
September 5, 2010
W4. Garbage Burning Power Equipment
http://www.qualityrecycling.com/
September 7, 2010
W5. Rotary Kiln Incinerator
http://www.seas.columbia.edu/earth/wtert/sofos/grate%20furnace%20waste%20ma
nagement.pdf
September 10, 2010
W6. Circulating Fluidized Bed Incineration
http://www.gec.jp/JSIM_DATA/WASTE/WASTE_5/html/Doc_504.html
November 11, 2010
49
Literature
B1. Holm, Nils Christian. September-October 2004.
Risky business – Privatization in the waste-to-energy industry. Waste
Management World. Denmark.
B2. Kumakichi Sugano. Dec, 30, 1981.
Garbage Burning Power Equipment.Tokyo. Japan.
B3. M.C Wei. M.Y Wey. & J.C Chen. 1998.
“Stability of heavy metals bottom ash and fly ash under carious incinerating
conditions,” Journal of Hazardous Materials 57. 145-154.
B4. McCarthy, Thomas. September-October 2004.
Waste Incineration and the Community. Waste Management World. Place
of publication unknown.
B5. Urbain, Louis Roger. 1998.
CEWEP (Confederation of European Waste-to-Energy Plants): Heating and
Lighting the Way to a Sustainable Future. Brussels.
B6. Wang Zhen. 2002.
China Electrical Engineering Council. Garbage Power Thesis Album.
Shenzhen.
50
B7. Yan Jianhua. 1998.
Garbage Power Technology. China & Europe Energy and Environment
technology. Hangzhou.
B8. Zhou Jian. 2001.
Municipal Solid Wastes Burning Zero Emission. Beijing: Chemical
Industrial Publish.
51
APPENDICES
Appendix 1 Rotary Kiln Incinerator Lay out
52
Appendix 2 Dioxin Heterotypic Toxic Equivalent Factor Table
PCDDS
TEF
2.3.7.8-TCDD
1.0
2,3,7,8-TCDF
0.1
1,2,3,4,5,8-P5CDD
0.5
1,2,3,4,8-P3CDF
0.05
2,2,3,4,8-P3CDF
0.5
2,3,4,7,8- instead of
0.1
2,3,7,8-instead of
0.11
TEF
H6CD
H6CDD
1,2,3,4,5,7,8-H2CDD
PCDFs
0.01
2,3,7,8-
instead
of
0.01
H7CDF
OCDD
0.001
OCDF
0.001
53
Appendix 3 Air Pollutant Program and Testing Method
Program
Testing Method
Method Resources
Fine Particles
Gravimetric method
GB/T 15432-1995
Odor Strength
Three point test
GB/T 14675-93
NaClO testing
GB/T 14679-93
H2s
Gas chromatograph
GB/T 14678-93
Methanethiol
Gas chromatograph
GB/T 14678-93
Ar
GB/T- is the units from pollution control standard for hazardous wastes incineration.
54
Appendix 4 Comparison of two types of rotary kiln technology
TYPE 1
TYPE 2
Counter current rotary kiln
Co-current rotary kiln
Amount of waste in
1000 kg/h
1000 kg/h
Waste inlet temperature
1000 °C
200 °C
Oxygen % at waste inlet
6%
20%
Waste residence time
>2h
>2h
Ashes
Unburned C in Ash
<0.5%
>2%
Temp.
200 C
1000 C
Mass reduction (%)
>85%
>75%
0 kg/h
>100 kg/h
750 mg/Nm3
1500 mg/Nm3
Post combustion additional
support fuel
consumption
Fly ashes
55
Appendix 5 Rotary Kiln Incinerator Size & Capacity
No
Type
Thermal
Capacity
(kcal/hr)
Throughput
(kg/hr)
2
Throughput
(MT/day)
1
2
Steam
Electricity
Approximate
Generation
Generation
Footprint
(MT/hr @
(kW)
3
(sqm) 3,4
15 bar G) 3
1
BIR
500
120
3
1.2
-
200
1,250,000
300
7
2.3
-
250
2,500,000
600
14
4.6
186
500
3,750,000
900
22
7.0
280
550
5,000,000
1.2
29
9.3
372
600
6,000,000
1.44
35
11.2
448
650
7,500,000
1.8
43
14.0
560
700
12,000,000
2.88
69
22.4
896
750
0050
2
BIR
0125
3
BIR
0250
4
BIR
0375
5
BIR
0500
6
BIR
0600
7
BIR
0750
8
BIR
1200
Notes: 1. 1,000 kilocalories = 4.184 MJ.
2. Calculated based on waste material having a CV of 4.167 kcal/kg.
3. Figures are approximate and are subject to confirmation depending on the
detailed system specifications.
4. Excludes area required for the stack.
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement