CFB Circulating Fluidized Bed Boiler coal fired boiler efficiency calculation
Fluidized Bed
1. At the bottom of the boiler furnace there is a bed of inert material. Bed is where the coal or fuel spreads. Air supply is from under the bed at high pressure. This lifts the bed material and the coal particles and keeps it in suspension. The coal combustion takes place in this suspended condition. This is the Fluidized bed.
2. Special design of the air nozzles at the bottom of the bed allows air flow without clogging. Primary air fans provide the preheated Fluidizing air. Secondary air fans provide pre-heated Combustion air. Nozzles in the furnace walls at various levels distribute the Combustion air in the furnace.
Circulation
1. Fine particles of partly burned coal, ash and bed material are carried along with the flue gases to the upper areas of the furnace and then into a cyclone. In the cyclone the heavier particles separate from the gas and falls to the hopper of the cyclone. 2. This returns to the furnace for recirculation. Hence the name Circulating Fluidized Bed combustion. The hot gases from the cyclone pass to the heat transfer surfaces and go out of the boiler.
Bed Material
1. To start with the bed material is sand. Some portion is lost in the ash during the operation and this has to be made-up. In coal fired boilers the ash from the coal itself will be the makeup material.
2. When firing bio fuels with very low ash content sand will be the makeup bed material. For high Sulphur coals Limestone addition to the bed material reduces SO2 emissions.
CFB High fuel flexibility
1. The main advantage of our boiler is its superb fuel flexibility. Most of the over 90 references around the world are multifuel boilers that combust biomasses and fossil fuels in continuously varying proportions.
2. Cocombustion is an environmentally benign method of combining excellent reliability and availability with great potential to optimize operational costs by allowing several fuel alternatives.
Main Specifications of Circulation Fluidized Bed Boiler
| boiler capacity
items | 35t/h | 75t/h | 130t/h |
| rated steam capacity t/h | 35 | 75 | 130 |
| rated working pressure Mpa | 3.82 | 3.82 | 5.3 |
| rated steam temperature℃ | 450 | 450 | 450 |
| feed water temperature ℃ | 105 | 130 | 150 |
| combustion method | Circulation fludized bed combustion | Circulation fludized bed combustion | Circulation fludized bed combustion |
| applicable coal | Coal | Coal | Coal |
| design the fuel low level caloric | 12670 | 8117 | 6520 |
| the coal consumption at full load operation(Kg/h) | 9045 | 20417 | 38792 |
| designed efficiency % | 88.6 | 88 | 88 |
| exit gas temperature ℃ | 150 | 145 | 150 |
| De-sulfur efficiency % | 88 | 88 | 88 |
| fuel particle requirement mm | ≤10 | ≤8 | ≤10 |
| lime stone particle requirement mm | ≤2 | ≤2 | ≤2 |
| drum central line elevation mm | 25000 | 28300 | 33000 |
| the highest point elevation l mm | 26750 | 33950 | 54270 |
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Vertical Fluidized Bed Furnace 90% Thermal Efficiency 450℃ Steam Temp Images
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