Division BAT 19 In order to increase the energy efficiency of the combustion of coal and/or lignite, BAT is to use an appropriate combination of the techniques given in BAT 12 and below.
United Kingdom
| Technique | Description | Applicability | |
|---|---|---|---|
| a. | Dry bottom ash handling | Dry hot bottom ash falls from the furnace onto a mechanical conveyor system and, after redirection to the furnace for reburning, is cooled down by ambient air. Useful energy is recovered from both the ash reburning and ash cooling | There may be technical restrictions that prevent retrofitting to existing combustion units |
Table 2
BAT-associated energy efficiency levels (BAT-AEELs) for coal and/or lignite combustion
| These BAT-AEELs do not apply in the case of units operated < 1 500 h/yr. | |||
| In the case of CHP units, only one of the two BAT-AEELs ‘Net electrical efficiency’ or ‘Net total fuel utilisation’ applies, depending on the CHP unit design (i.e. either more oriented towards electricity generation or towards heat generation). | |||
| The lower end of the range may correspondent to cases where the achieved energy efficiency is negatively affected (up to four percentage points) by the type of cooling system used or the geographical location of the unit. | |||
| These levels may not be achievable if the potential heat demand is too low. | |||
| These BAT-AEELs do not apply to plants generating only electricity. | |||
| The lower ends of the BAT-AEEL ranges are achieved in the case of unfavourable climatic conditions, low-grade lignite-fired units, and/or old units (first commissioned before 1985). | |||
| The higher end of the BAT-AEEL range can be achieved with high steam parameters (pressure, temperature). | |||
| The achievable electrical efficiency improvement depends on the specific unit, but an increase of more than three percentage points is considered as reflecting the use of BAT for existing units, depending on the original design of the unit and on the retrofits already performed. | |||
| In the case of units burning lignite with a lower heating value below 6 MJ/kg, the lower end of the BAT-AEEL range is 41,5 %. | |||
| The higher end of the BAT-AEEL range may be up to 46 % in the case of units of ≥ 600 MWth using supercritical or ultra-supercritical steam conditions. | |||
| The higher end of the BAT-AEEL range may be up to 44 % in the case of units of ≥ 600 MWth using supercritical or ultra-supercritical steam conditions. | |||
| Type of combustion unit | BAT-AEELsf1 f2 | ||
|---|---|---|---|
| Net electrical efficiency (%)f3 | Net total fuel utilisation (%) f4 f5 | ||
| New unitf6 f7 | Existing unit f8 | New or existing unit | |
| Coal-fired, ≥ 1 000 MWth | 45 – 46 | 33,5 – 44 | 75 – 97 |
| Lignite-fired, ≥ 1 000 MWth | 42 – 44f9 | 33,5 – 42,5 | 75 – 97 |
| Coal-fired, < 1 000 MWth | 36,5 – 41,5f10 | 32,5 – 41,5 | 75 – 97 |
| Lignite-fired, < 1 000 MWth | 36,5 – 40f11 | 31,5 – 39,5 | 75 – 97 |
Annotations
Footnotes
- f1
-
These BAT-AEELs do not apply in the case of units operated < 1 500 h/yr.
- f2
-
In the case of CHP units, only one of the two BAT-AEELs ‘Net electrical efficiency’ or ‘Net total fuel utilisation’ applies, depending on the CHP unit design (i.e. either more oriented towards electricity generation or towards heat generation).
- f3
-
The lower end of the range may correspondent to cases where the achieved energy efficiency is negatively affected (up to four percentage points) by the type of cooling system used or the geographical location of the unit.
- f4
-
These levels may not be achievable if the potential heat demand is too low.
- f5
-
These BAT-AEELs do not apply to plants generating only electricity.
- f6
-
The lower ends of the BAT-AEEL ranges are achieved in the case of unfavourable climatic conditions, low-grade lignite-fired units, and/or old units (first commissioned before 1985).
- f7
-
The higher end of the BAT-AEEL range can be achieved with high steam parameters (pressure, temperature).
- f8
-
The achievable electrical efficiency improvement depends on the specific unit, but an increase of more than three percentage points is considered as reflecting the use of BAT for existing units, depending on the original design of the unit and on the retrofits already performed.
- f9
-
In the case of units burning lignite with a lower heating value below 6 MJ/kg, the lower end of the BAT-AEEL range is 41,5 %.
- f10
-
The higher end of the BAT-AEEL range may be up to 46 % in the case of units of ≥ 600 MWth using supercritical or ultra-supercritical steam conditions.
- f11
-
The higher end of the BAT-AEEL range may be up to 44 % in the case of units of ≥ 600 MWth using supercritical or ultra-supercritical steam conditions.