1. DEVELOPMENT AND APPLICATION OF PROMISING TECHNOLOGIES FOR
FIRING COAL-WATER FUELS
Coal-Gen Europe 2008
F. Serant , K. Agapov , A. Kuzmin,
Yu. Ovchinnikov, L. Pugach
SibCOTES, NSTU
Novosibirsk
Russian Federation
Ladies and Gentlemen, I consider it a special honour to make a presentation on such a representative forum
and I would like to thank the organizers of the conference for this opportunity.
I will speak about technologies for coal-water fuels production & firing

2. CONTENTS
Problems and prospects for coal-water firing at power generation installations
Experience of application of coal-water fuel at Novosibirsk CHP-5 Plant & Belovskaya PP
Advanced coal-water technologies developed together with Novosibirsk State Technical Institute & Novosibirskteploelectroproect
My presentation covers the following issues:
The first point concerns the problems and prospects for coal-water firing
Experience of application of coal-water fuel
The next point is
Advanced coal-water technologies
And in summary I will sum up the results of our study and give the main conclusions regarding coal-water fuel production and firing
Main conclusions
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3. Power industry & coal-water fuel in Russia
Tons of coal equivalent
It is well-known that the development of power industry in Russia for the next years will rely on the increased use of coal both due to economical reasons and the need to ensure energy safety. Oil and gas resources will last for several decades, while coal resources will last for centuries.
The use of coal-water fuel is one of the ways for a wider application of coal in power generation along with conventional pulverized coal firing and fuel-bed firing. At present, the use of coal-water fuel instead of oil at thermal power plants is considered to be very promising.
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4. Advantages of coal-water fuel
Coal-water slurry is a relatively new type of fuel for small- and large-scale power installations.
It has a number of advantages compared to conventional fuels:
Long-distance pipeline transition
No explosion hazard
Lower NOx and SOx emission level
Coal-water slurry is a relatively new type of fuel for small- and large-scale power installations.
It has a number of advantages compared to conventional fuels:
Long-distance pipeline transition
No explosion hazard
Lower NOx and SOx emission level
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5. Requirements for coal-water fuel
General requirements for coal-water fuels:
Suitable viscosity - about 0.5–1.0 Pa·s with shear rate 100 s-1
Certain stability of properties when stored in tanks for months
Ensuring the conditions for stable direct combustion: acceptable heating value, reactivity, and good dispersing properties (drops up to 350 μm)
Fired fuel should ensure efficient combustion, as well as reduced emissions
Eliminate covering and slagging of heating surfaces
General requirements for coal-water fuels production process:
Acceptable power inputs per 1 ton of product
Moderate wear and metal intensity per 1 ton of the product
Long overhaul life for the elements (mills, cavitators, dispersers, fuel nozzles)
Automation ensuring proper operation level
To substitute gas and oil, it should meet the following requirements.
Suitable viscosity
Certain stability of properties
Ensuring the conditions for stable direct combustion
Fired fuel should ensure efficient combustion, reduced emission level without covering and slagging of heating surfaces
General requirements for coal-water fuels production process are the following:
Acceptable power inputs
Moderate wear and metal intensity
Long overhaul life for the elements
Automation ensuring proper operation level
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6. Coal-water fuel combustion on a 200 MW unit at Belovskaya Power Plant
Coal-water slurry conditions:
Kuznetsky coal, grades D
(long-flame coal)
Kuznetsky G (gas coal)
Qir =15.1 MJ/kg
Wr = 39%
Ar =9%
Nr = 1.45%
Density ρ=1180÷1220 kg/m3
Viscosity μ = 0.5÷1.2 Pa·s
Russia has a wide experience of application of various technologies for coal-water fuel preparation and firing.
Combustion of coal-water fuel prepared in conventional wet mills was tested on several 200 MW power units at Belovskaya Power Plant in Siberia.
This slide presents the scheme of reception, storage and firing of coal-water fuel at Belovskaya Power Plant as well as coal-water fuel parameters.
6000 tons of fuel were fired at the boiler with wet slag removal sysytem.
Coal-water fuel was based on Kuznetsky long-flame and gas coal.
Boiler PK-40-1:
Steaming capacity = 320 t/h
Furnace heat release rate qv= 130 kW/m3
Furnace cross-section heat release rate qF= 3.8 MW/m2
6000 tons of coal-water fuel were fired
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7. Application of coal-water fuel at Novosibirsk CHP-5 Plant
Pilot coal slurry pipeline Belovo – Novosibirsk
262 km-long coal slurry pipeline
4 million tons of coal-water fuel per year
3 million tons of dry coal per year
Novosibirsk CHP-5 Plant has an experience of reception, storage and firing of coal-water fuel as well.
This fuel produced at Belovo terminal in the Kuzbass region
and transmitted through a 262 km-long coal slurry pipeline.
At this slide you can see coal-water fuel preparation unit, the main and intermediary pumping stations and reception point
where the fuel is heated and further forwarded to the boilers.
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8. Coal-water fuel handling and storage system
Two tanks
(20 000 m3 each)
with hydro mixers
Air
compressor
Compressed air
The terminal, final point of the coal slurry pipeline, is given at the next slide.
It technologically consists of three systems that receive, store and supply coal-water fuel for firing.
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9. Coal-water fuel combustion on boiler at Novosibirsk CHP Plant
Boiler performance:
Steaming capacity t/h
1 boiler was completely re-equipped for coal-water fuel firing (together with Snamprogetti)
3 boilers fired it together with conventional Kuznetsky coal (grades D (long-flame coal) and G (gas coal)).
Low heat release rates - qv = 95 kW/m3 and qF = 3.4 MW/m2.
Coal-water fuel conditions:
Coal concentration in the coal-water fuel %
Coal-water fuel density – ρ=1.21 g/cm3
Ash content Ad=9.5 %
Calorific value Qir = MJ/kg
During the process of coal-water firing at dry-bottom furnace boilers at Novosibirsk CHP Plant one boiler was completely re-equipped with coal-water fuel firing system. 3 other boilers fired coal-water fuel together with coal.
Coal quality:
Qir =22,7 MJ/kg
Ad=12.5 %
Wr =14.6%
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10. Conclusions after coal-water fuel firing at Belovskaya PP and Novosibirsk CHP-5 Plant
Switching of the existing PC-fired boilers to coal-water fuel without any additional reconstruction results in the following:
Lower gas temperature in the flame kernel (by °С)
Lower cost-efficiency of combustion (by %)
Higher gas temperature at the furnace tail (by 35-45°С) and downstream the boiler by 15-20°С
Lower NOx level under certain conditions (by 25-35%)
To eliminate adverse effects the boilers need some re-engineering, incl.:
Heat insulation of the furnace to increase gas temperature within the flame kernel
Changed superheater and economizer surfaces
Finer coal grinding
Higher hot air temperature
Transmission system for coal-water fuel (Belovo – Novosibirsk) with conventional milling and mixing with water has some disadvantages:
Limited time of being in a stable condition
Abrasivity of coal-water fuel, which causes considerable wear of pumps, gate valves, fuel nozzles, etc.
Need to use surface-active substances
Based on the experience of coal-water fuel firing we can make the following conclusions.
Switching of the existing PC-fired boilers to coal-water fuel without reconstruction results in flame kernel temperature decrease and cost-efficiency reduction, but NOx level is lower.
Thus, it is necessary to carry out a certain reconstruction to avoid the negative consequences.
Conventional milling and mixing within the transmission system for coal-water fuel revealed a number of drawbacks.
For this reason it seems very important to develop advanced technologies, which meet specific requirements.
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11. Cavitation of coal-water fuel
Technology developed together with
company NovosibirskTeploelectroproekt
New technology for coal-water fuel production was developed together with Novosibirskteploelektroproekt
This advanced technology is based on mechanical and chemical activation making use of cavitation technology.
This cavitation technology is featured by the stability over a long period of time and plasticity without using any additives.
Based on the operational experience installations with different capacities (from 5 to 300 tons per hour of source coal) were developed.
Capacity from 5 to 300 t/h of sourse coal
Coal-water fuel stability – more than 24 months
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12. Production and supply of composite liquid fuel to boiler
Coal-water technologies developed by Novosibirsk State Technical University (NSTU)
1 – coal hopper
2 – crusher
3 – feeder
4 – desintegrator
5 – separator
6 – cyclone
7 – FDF
8 – PC bunker
9 – feeder
10 – cavitators
11 – raw oil tank (oil and fuel oil residue)
12 – daily tank for composite liquid fuel
13 – recirculation line of composite liquid fuel
14 – water-supply tank
15 – peat hopper
16 – screen
17 – flotation plant
18 – peat gel feed line
19 – feeding pump of composite liquid fuel
20 – feed line of composite liquid fuel
21 – FDF
22 – feed line for coal-water mixture after the first cavitation stage
Another technology was developed in cooperation with NSTU. This technology is based on the use of coal dust and crushed peat using molecular decomposition in a multi-stage cavitators and disintegrators.
As a result the final product – composite liquid fuel, meets the required physical-and-technical conditions of liquid fuel.
Production and supply of composite liquid fuel to boiler
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13. Coal-water production technology features
Stability of the system is more than 1 year
Basic methods of stabilization:
Mechanical-chemical activation of solid phase during grinding in a desintegrator
Mechanical-chemical activation of liquid phase in a cavitator
Creation of stable physical-chemical fuel system through profound homogenization of activated phase in a cavitator
Due to mecanical & chemical activation the received fuel has an in-depth dispersed composition & long period of stability
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14. Main equipment for the technology
Desintegrator is a high-speed mill with percussive-smashing effect.
Desintegrator output is 3 t/h
Activation of coal particles is realized through deformation of coal structure and through creation of micro-defects on the surface of coal particles.
These processes were realized on high-speed dry milling grinders for solid phase,
so-called disintegrating mills.
Solid and liquid phases were mechanically and chemically activated.
Coal is grinded to almost minimum size.
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15. Main equipment for the technology
Cavitator functions:
Further grinding of solid phase material
Homogenization of liquid and solid particles mixture
Creation of stable physical chemical liquid fuel system
Major feature - Shock-thermal effect in the cavitator zone;
This impact leads to:
activation of liquid
destruction of connections in the clusters of the liquid
creation of free radicals and active molecules.
Cavitator: output - 3 tons per hour ACLF
A shock-wave effect in cavitator zone leads to activation of liquid,
destruction of connections in the clusters of the liquid,
creation of free radicals and active molecules.
Activated particles of coal and activated liquid
create stable physical-chemical system during homogenization process.
The stability of this coal-water fuel is much higher than that of coal-water fuel received using conventional milling and mixing.
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16. Production of synthetic composite liquid fuel
Main technical characteristics of the new technology:
Specific energy consumption ~ kW per ton of product
Specific metal consumption ~ t per ton of product in terms of the main equipment
Reasonable cost of equipment
Production area ~ 8 m2/t
Production of synthetic composite liquid fuel:
1 – coal tank; 2 – coal feeder; 3 – crusher; 4 – disintegrator; 5 – mixer with water; 6 – cavitator; 7 – intermediate tank; 8 – tank for finished composite liquid fuel
Due to the need in new equipment for a new type of fuel NSTU developed and brought to commercial application a processing plant for synthetic composite liquid fuel production.
The main feature of the technology is that synthetic composite fuel includes complementary components, and as a result we can obtain a better fuel compared to the source components. The composite liquid fuel should be a homogenized system.
The scheme of composite liquid fuel production is given at the slide.
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17. Module for synthetic composite fuel production
Composite liquid fuel production lines can be developed both for the production of synthetic composite liquid fuel and for synthetic composite solid fuel.
As you can see on this slide, the synthetic composite liquid fuel is an intermediate product.
At this point the stage for synthetic composite liquid fuel preparation is completed.
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18. Received fuels & their combustion
Line 1: Wr = 64 %, coal – 20 %, peat – 8 %, oil – 8 %, Ad =28 %;
Line 2: Wr = 54.5 %, coal – 45.5 %, Ad =27.8 %;
Line 3: Wr = %, coal – 17 %, peat – 10 %, fuel oil – 17 %, Ad =19.5 %;
In addition, coal-based fuel without any peat component was received:
Line А: Wr = 35.5%, coal – 39.5%, oil - 25%, Аd = 10.3 %;
Line G: Wr = 48.6%, coal – 43.4%, oil - 8%, Ad= 19.5 %.
Mail results of fuel lines studies:
Viscosity of the synthetic composite liquid fuel does not depend on the temperature within the operating temperature range and on the shear rate within the operating velocities, it depends on the composition and is similar to operating viscosity of fuel oils. Synthetic composite liquid fuel is a thixotropic fluid.
Combustion process confirmed reliable flame ignition of sprayed synthetic composite liquid fuel and its independent stable combustion.
Emissions when firing coal-water fuel are: NOx = mg/Nm3 (with O2 = 6 %), SO2 = mg/Nm3.
Using the technology several lines of synthetic composite liquid fuel were prepared making use of anthracite fines, peat and black coal. Crude oil and fuel oil were used as additives. All mentioned components and received fuel were studied and tested in the laboratories.
Our studies have shown that viscosity of the synthetic composite liquid fuel does not depend on the temperature, but it significantly depends on the composition. Generally its viscosity is similar to that of fuel oil.
The received experience has proved the reliable ignition, stable burning and low NOx and SO2 levels.
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19. Conclusions
Presented technologies make it possible to produce a fundamentally new type of synthetic fuel based on coal, water and other components;
Rheological, sedimentation, heat-and-power requirements for this fuel were defined;
In order to burn synthetic composite fuel on existing PC-fired boilers with good efficiency, it is necessary to reconstruct such boilers;
The fuel meets the requirements set for the coal-water fuels;
New composite fuel can be used both for firing in various combustion chambers, and as a fuel for internal-combustion engines, gas turbine fuel and fuel for gasifiers, or instead of oil fuel for boilers and TPPs;
Research works for the preparation and combustion of synthetic composite liquid fuel making use of local fuels (different grades of peat), coal treatment products, wood waste, farm and oil refinery waste are still in progress.
All implemented research and development, pilot and design efforts allow us to make the following conclusions:
Described technologies make it possible to produce a fundamentally new type of fuel
Requirements for this fuel were defined
To ensure good performance during coal-water fuel firing on the existing PC-fired boilers some reconstruction is required.
Developed fuel meets the requirements set for the coal-water fuels;
New composite fuels can be used for different applications: boilers, gasifiers, instead of oil fuel and coal and so on.
Research works for the preparation and combustion of synthetic composite liquid fuel are still in progress.
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20. Thank you for your attention!