About Coal Water Slurry - CWS

specifics, technologies and advantages:

 

 

 

 

 

 

 

 

 

 

 

 

• As a consequence of the actual energy situation, the dependency on a view oil and gas suppliers,

     the use of the “forgotten fuel”,  coal water slurry - CWS and Coal Oil Slurry - COS ,

     are now increasingly used  worldwide, especially in Asia so far.

 

• Volatile oil and gas markets experienced in the recent years , have promoted renewed interest in coal-based fuel technologies. Coal-slurry fuels have emerged as viable technical alternatives for oil and gas in utility and industrial boilers. Despite current low prices and the abundance of oil, concerns over its long-term availability and price, as well as strategic considerations, make coal-slurry technology very attractive

 

•  For decades, CWS and COS have been developed as a  substitute for oil in many industries and power plant boilers, gasifiers, swirl and and fluidized bed combustors.

 

• CWS is actually widely used in China by over 100 power plant boilers, as pure CWS systems or combined ones, hundreds industrial furnaces, and hundreds of various kilns since 2007.

 

Coal water slurry characteristics:

General characteristics

• Coal Water Slurry (CWS) is a new type of liquid fuel, environmentally friendly with very strong potential to substitute  Oil / Gas used in industrial hot water and steam boilers with significant cost savings and ease of handling.

• CWS is a homogeneous mix of fine milled coal/carbon (from all types of coal, oil coke, tyres (after pyrolysis) and water.

• CWS usually consists of 57-66 % of solid parts and 34-43 % water. Sometimes CWS includes additives. Additives up to 2 %

• The flame temperature in CWS combustion is lower by 100~150 C than that in pulverized coal combustion. Thus the combustion of  CWS generally emits less fly ash, SO2, and NOx than traditional coal-fired boilers.

• The presence of water in CWS reduces harmful emissions into the atmosphere and makes the coal explosion-proof

•  A coal-water slurry is defined by its viscosity, sedimentation (retention uniformity in static and fuel characteristics (energy potential, full burning of the organic compounds) .

 

• The characteristics of CWM compared with the traditional solid coal, CWM has many excellent characteristics, bringing the social environmental protection benefit and enterprise economic benefit directly.

• The density is high, rheology is good and it can be stored for a long-term without deposition. So it can be transmitted through pumps and burned with atomization similar to the fuel. It can replace the fuel completely in the industrial boiler, industrial kiln and the power station boiler, its comprehensive economic cost is much lower than burning the fuel greatly.

• Its exhausted rate increases from 70-80% of the trraditional coal combustion to more than 98%. The carbon percentage in slag reduces from 13.7% of the coal to less than 2%.Therefore, it fully represents the characteristics of environment protection and energy saving.

• CWM is transported and stored in tanks similar to the fuel which reduces the contamination of the solid coal during the transportation and the storage area. There is no danger in the storage and transportation because of its physical chemistry composition characteristics.

• Since its exhausted rate reaches more than 98%, the discharged slag is reduced significantly, compared with the coal-burning boiler, which not only reduces the total cover area of the boiler house but also enhances the circumjacent environment.

• Since it is burnt automatically in a liquid state within a system, the working environment and condition is greatly enhanced compared with the traditional coal-burning boiler. It stops the smell of the lampblack and coal basically in the boiler building with the special CWM combustion technique.

   

Specifics and Properties: 

 

• Calorific value - 3700-4700 kcal/kg, depending on coal type and quality

• Viscosity:~1000CP

• Density ：65~70%

• Ignition temp.: 425 - 550  °C

• Combustion temp.: 950 - 1350 °C

• Moisture: 30-40 %

• Ash: 2-20 %, depending on coal type and quality

• Sulfor: <0,5 %

• Althoug CWS is similar to coal, these energy resources significantly differ from each other.

• CWS is combusted after it is atomized, similar to other liquid fuels

 

CWS advantages:

 

• Coal water slurry is a cheap energy resource. It is a low cost fuel: Because of the relatively low cost of coal when compared to other energy sources, CWS is a very competitive alternative to heating with oil and gas. Depending on geographical area the price per unit energy of CWS may be 30% to 70% lower than the equivalent oil or gas. Heat or electricity produced from CWS is cheaper than from oil, diesel, gas.

 

• CWS is cost effective and environmental friendly: Low emissions and low BTU cost (Gcal or MWh) make CWS very cost effective and environmental friendly fuel for heat and power generation.

 

• CWS is easy to transport (pumped through pipes, per tanktruck, tank wagon, barks)

 

• Existing oil or gas fired systems can be adapted for CWS combustion without major modifications

 

• Wide and simple load adjustment range: load range can adjust from 35% to 100%, economical choice.

 

• Coal-water slurry fuel is fire- and explosion-proof, it is easy  and save to store and to transport (pipelines, tanks),  no dust pollution, no need coal storage yard and slag yard, improve the use ratio of land, save 50% land area.

 

• Low temperature combustion: Coal water slurry boiler can heat up to and maintain 900°C-1200 °C in a very little time, which avoid the Incomplete combustion during the low temperature period, also avoid producing a lot of the NOx of oil/gas fired boiler  when temperature is above 1300°C.

 

• Ash after the CWS combustion is an ideal amendment to special concrete production.  CWS boiler fly ash emission concentration is about 100mg/Nm3,  ash can be used and sold as very valuable co-material of concrete production,  received by the integrated dry fly ash collection system.

 

• Gas or oil/diesel still could be used as fuel for preheating of the system or for special "heat peak shocks".