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ANNEXU.K.BAT CONCLUSIONS FOR THE PRODUCTION OF PULP, PAPER AND BOARD

ACRONYMS U.K.

1.2.BAT CONCLUSIONS FOR KRAFT PULPING PROCESSU.K.

For integrated kraft pulp and paper mills, the process-specific BAT conclusions for papermaking given in Section 1.6 apply, in addition to the BAT conclusions in this section.

1.2.1. Waste water and emissions to water U.K.
BAT 19.In order to reduce emissions of pollutants into receiving waters from the whole mill, BAT is to use TCF or modern ECF bleaching (see description in Section 1.7.2.1), and a suitable combination of the techniques specified in BAT 13, BAT 14, BAT 15 and BAT 16 and of the techniques given below.U.K.
TechniqueDescriptionApplicability
aModified cooking before bleachingSee Section 1.7.2.1Generally applicable
bOxygen delignification before bleaching
cClosed brown stock screening and efficient brown stock washing
dPartial process water recycling in the bleach plantWater recycling may be limited due to incrustation in bleaching
eEffective spill monitoring and containment with a suitable recovery systemGenerally applicable
fMaintaining sufficient black liquor evaporation and recovery boiler capacity to cope with peak loadsGenerally applicable
gStripping the contaminated (foul) condensates and reusing the condensates in the process
BAT-associated emission levels U.K.

See Table 1 and Table 2. These BAT-associated emission levels are not applicable to dissolving kraft pulp mills.

The reference waste water flow for kraft mills is set out in BAT 5.

Table 1

BAT-associated emission levels for the direct waste water discharge to receiving waters from a bleached kraft pulp mill

a

The BAT-AEL ranges refer to market pulp production and the pulp production part of integrated mills (emissions from papermaking are not included).

b

A compact biological waste water treatment plant can result in slightly higher emission levels.

c

The upper end of the range refers to mills using eucalyptus from regions with higher levels of phosphorus (e.g. Iberian eucalyptus).

d

Applicable for mills using chlorine containing bleaching chemicals.

e

For mills producing pulp with high strength, stiffness and high purity properties (e.g. for liquid packaging board and LWC), emissions level of AOX up to 0,25 kg/ADt may occur.

ParameterYearly averagekg/ADta
Chemical oxygen demand (COD)7 – 20
Total suspended solids (TSS)0,3 – 1,5
Total nitrogen0,05 – 0,25b
Total phosphorus

0,01 – 0,03b

Eucalyptus: 0,02 – 0,11 kg/ADtc

Adsorbable organically bound halogens (AOX)d e0 – 0,2
Table 2

BAT-associated emission levels for the direct waste water discharge to receiving waters from an unbleached kraft pulp mill

a

The BAT-AEL ranges refer to market pulp production and the pulp production part of integrated mills (emissions from papermaking are not included).

b

A compact biological waste water treatment plant can result in slightly higher emission levels.

ParameterYearly averagekg/ADta
Chemical oxygen demand (COD)2,5 – 8
Total suspended solids (TSS)0,3 – 1,0
Total nitrogen0,1 – 0,2b
Total phosphorus0,01 – 0,02b

The BOD concentration in the treated effluents is expected to be low (around 25 mg/l as a 24-hour composite sample).

1.2.2. Emissions to air U.K.
1.2.2.1. Reduction of emissions in strong and weak odorous gases U.K.
BAT 20.In order to reduce odour emissions and total reduced sulphur emissions due to strong and weak odorous gases, BAT is to prevent diffuse emissions by capturing all process-based sulphur containing off-gases, including all vents with sulphur-containing emissions, by applying all of the techniques given below.U.K.
a

The SOx emission levels of the lime kiln increase significantly when strong non-condensable gases (NCG) are fed to the kiln and no alkaline scrubber is used.

b

Applicable for the treatment of weak odorous gases.

c

Applicable for the treatment of strong odorous gases.

TechniqueDescription
a

Collection systems for strong and weak odorous gases, comprising the following features:

  • covers, suction hoods, ducts, and extraction system with sufficient capacity;

  • continuous leak detection system;

  • safety measures and equipment.

bIncineration of strong and weak non-condensable gases

Incineration can be carried out using:

  • recovery boiler

  • lime kilna

  • dedicated TRS burner equipped with wet scrubbers for SOx removal; or

  • power boilerb

To ensure the constant availability of incineration for odorous strong gases, back-up systems are installed. Lime kilns can serve as back-up for recovery boilers; further back-up equipment are flares and package boiler

cRecording unavailability of the incineration system and any resulting emissionsc
Applicability U.K.

Generally applicable for new plants and for major refurbishments of existing plants. The installation of necessary equipment may be difficult for existing plants due to layout and space restrictions. The applicability of incineration might be limited for safety reasons, and in this case wet scrubbers could be used.

BAT-associated emission level of total reduced sulphur (TRS) in residual weak gases emitted is 0,05 – 0,2 kg S/ADt.

1.2.2.2. Reduction of emissions from a recovery boiler U.K.
SO2 and TRS emissionsU.K.
BAT 21.In order to reduce SO2 and TRS emissions from a recovery boiler, BAT is to use a combination of the techniques given below.U.K.
TechniqueDescription
aIncreasing the dry solids (DS) content of black liquorThe black liquor can be concentrated by an evaporation process before burning
bOptimised firingFiring conditions can be improved e.g. by good mixing of air and fuel, control of furnace load etc.
cWet scrubberSee Section 1.7.1.3
BAT-associated emission levels U.K.

See Table 3.

Table 3

BAT-associated emission levels for SO2 and TRS emissions from a recovery boiler

a

Increasing the DS content of the black liquor results in lower SO2 emissions and higher NOx emissions. Due to this, a recovery boiler with low emission levels for SO2, may be on the higher end of the range for NOx and vice versa.

b

BAT-AELs do not cover periods during which the recovery boiler is run on a DS content much lower than the normal DS content due to shut down or maintenance of the black liquor concentration plant.

c

If a recovery boiler were to burn black liquor with a DS > 83 %, then SO2 and gaseous S emission levels should be reconsidered on a case-by-case basis.

d

The range is applicable without the incineration of odorous strong gases.

DS = dry solid content of the black liquor.

ParameterDaily averagea bmg/Nm3 at 6 % O2Yearly averageamg/Nm3 at 6 % O2Yearly averageakg S/ADt
SO2DS < 75 %10 – 705 – 50
DS 75 – 83 %c10 – 505 – 25
Total reduced sulphur (TRS)1 – 10d1 – 5
Gaseous S (TRS-S + SO2-S)DS < 75 %0,03 – 0,17
DS 75 – 83 %c0,03 – 0,13
NOx emissionsU.K.
BAT 22.In order to reduce NOx emissions from a recovery boiler, BAT is to use an optimised firing system including all of the features given below.U.K.
Technique
aComputerised combustion control
bGood mixing of fuel and air
cStaged air feed systems, e.g. by using different air registers and air inlet ports
Applicability U.K.

Technique (c)is applicable to new recovery boilers and in the case of a major refurbishment of recovery boilers, as this technique requires considerable changes to the air feed systems and the furnace.

BAT-associated emission levels U.K.

See Table 4.

Table 4

BAT-associated emission levels for NOx emissions from a recovery boiler

a

Increasing the DS content of the black liquor results in lower SO2 emissions and higher NOx emissions. Due to this, a recovery boiler with low emission levels for SO2, may be on the higher end of the range for NOx and vice versa.

b

The actual NOx emission level of a recovery boiler depends on the DS content and the nitrogen content of the black liquor, and the amount and combination of NCG and other nitrogen containing flows (e.g. dissolving tank vent gas, methanol separated from the condensate, biosludge) burnt. The higher the DS content, the nitrogen content in the black liquor, and the amount of NCG and other nitrogen containing flows burnt, the closer the emissions will be to the upper end of the BAT-AEL range.

c

If a recovery boiler were to burn black liquor with a DS > 83 %, then NOx emission levels should be reconsidered on a case-by-case basis.

DS = dry solid content of black liquor.

ParameterYearly averageamg/Nm3 at 6 % O2Yearly averageakg NOx/ADt
NOxSoftwood120 – 200b

DS < 75 %: 0,8 – 1,4

DS 75 – 83 %c: 1,0 – 1,6

Hardwood120 – 200b

DS < 75 %: 0,8 – 1,4

DS 75 – 83 %c: 1,0 – 1,7

Dust emissionsU.K.
BAT 23.In order to reduce dust emissions from a recovery boiler, BAT is to use an electrostatic precipitator (ESP) or a combination of ESP and wet scrubber.U.K.
Description U.K.

SeeSection 1.7.1.1.

BAT-associated emission levels U.K.

See Table 5.

Table 5

BAT-associated emission levels for dust emissions from a recovery boiler

a

For an existing recovery boiler equipped with an ESP approaching the end of its operational life, emission levels may increase over time up to 50 mg/Nm3 (corresponding to 0,4 kg/ADt).

ParameterDust abatement systemYearly averagemg/Nm3 at 6 % O2Yearly averagekg dust/ADt
DustNew or major refurbishment10 – 250,02 – 0,20
Existing10 – 40a0,02 — 0,3a
1.2.2.3. Reduction of emissions from a lime kiln U.K.
SO2 emissionsU.K.
BAT 24.In order to reduce SO2 emissions from a lime kiln, BAT is to apply one or a combination of the techniques given below.U.K.
TechniqueDescription
aFuel selection/low sulphur fuelSee Section 1.7.1.3
bLimit incineration of sulphur-containing odorous strong gases in the lime kiln
cControl of Na2S content in lime mud feed
dAlkaline scrubber
BAT-associated emission levels U.K.

See Table 6.

Table 6

BAT-associated emission levels for SO2 and sulphur emissions from a lime kiln

a

‘strong gases’ includes methanol and turpentine

ParameteraYearly averagemg SO2/Nm3 at 6 % O2Yearly averagekg S/ADt
SO2 when strong gases are not burnt in the lime kiln5 – 70
SO2 when strong gases are burnt in the lime kiln55 – 120
Gaseous S (TRS-S + SO2-S) when strong gases are not burnt in the lime kiln0,005 – 0,07
Gaseous S (TRS-S + SO2-S) when strong gases are burnt in the lime kiln0,055 – 0,12
TRS emissionsU.K.
BAT 25.In order to reduce TRS emissions from a lime kiln, BAT is to apply one or a combination of the techniques given below.U.K.
TechniqueDescription
aControl of the excess oxygenSee Section 1.7.1.3
bControl of Na2S content in lime mud feed
cCombination of ESP and alkaline scrubberSee Section 1.7.1.1
BAT-associated emission levels U.K.

See Table 7.

Table 7

BAT-associated emission levels for TRS emissions from a lime kiln

a

For lime kilns burning strong gases (including methanol and turpentine), the upper end of the AEL range may be up to 40 mg/Nm3.

ParameterYearly averagemg S/Nm3 at 6 % O2
Total reduced sulphur (TRS)< 1 – 10a
NOx emissionsU.K.
BAT 26.In order to reduce NOx emissions from a lime kiln, BAT is to apply a combination of the techniques given below.U.K.
TechniqueDescription
aOptimised combustion and combustion controlSee Section 1.7.1.2
bGood mixing of fuel and air
cLow-NOx burner
dFuel selection/low-N fuel
BAT-associated emission levels U.K.

See Table 8.

Table 8

BAT-associated emission levels for NOx emissions from a lime kiln

a

When using liquid fuels originating from vegetable matter (e.g. turpentine, methanol, tall-oil), including those obtained as by-products of the pulping process, emission levels up to 350 mg/Nm3 (corresponding to 0,35 kg NOx/ADt) may occur.

b

When using gaseous fuels originating from vegetable matter (e.g. non-condensable gases), including those obtained as by-products of the pulping process, emission levels up to 450 mg/Nm3 (corresponding to 0,45 kg NOx/ADt) may occur.

ParameterYearly averagemg/Nm3 at 6 % O2Yearly averagekg NOx/ADt
NOxLiquid fuels100 – 200a0,1 – 0,2a
Gaseous fuels100 – 350b0,1 – 0,3b
Dust emissionsU.K.
BAT 27.In order to reduce dust emissions from a lime kiln, BAT is to use an electrostatic precipitator (ESP) or a combination of ESP and wet scrubber.U.K.
Description U.K.

See Section 1.7.1.1.

BAT-associated emission levels U.K.

See Table 9.

Table 9

BAT-associated emission levels for dust emissions from a lime kiln

a

For an existing lime kiln equipped with an ESP approaching the end of its operational life, emission levels may increase over time up to 50 mg/Nm3 (corresponding to 0,05 kg/ADt).

ParameterDust abatement systemYearly averagemg/Nm3 at 6 % O2Yearly averagekg dust/ADt
DustNew or major refurbishments10 – 250,005 – 0,02
Existing10 – 30a0,005 – 0,03a
1.2.2.4. Reduction of emissions from a burner for strong odorous gases (dedicated TRS burner) U.K.
BAT 28.In order to reduce SO2 emissions from the incineration of strong odorous gases in a dedicated TRS burner, BAT is to use an alkaline SO2 scrubber.U.K.
BAT-associated emission levels U.K.

See Table 10.

Table 10

BAT-associated emission levels for SO2 and TRS emissions from the incineration of strong gases in a dedicated TRS burner

a

This BAT-AEL is based on a gas flow in the range of 100-200 Nm3/ADt.

ParameterYearly averagemg/Nm3 at 9 % O2Yearly averagekg S/ADt
SO220 – 120
TRS1 – 5
Gaseous S (TRS-S + SO2-S)0,002 – 0,05a
BAT 29.In order to reduce NOx emissions from the incineration of strong odorous gases in a dedicated TRS burner, BAT is to use one or a combination of the techniques given below.U.K.
TechniqueDescriptionApplicability
aBurner/firing optimisationSee Section 1.7.1.2Generally applicable
bStaged incinerationSee Section 1.7.1.2Generally applicable for new plants and for major refurbishments. For existing mills, applicable only if space allows for the insertion of equipment
BAT-associated emission levels U.K.

See Table 11.

Table 11

BAT-associated emission levels for NOx emissions from the incineration of strong gases in a dedicated TRS burner

a

Where at existing plants a switch to staged incineration is not feasible, emissions levels up to 1 000 mg/Nm3 (corresponding to 0,2 kg/ADt) may occur.

ParameterYearly averagemg/Nm3 at 9 % O2Yearly averagekg NOx/ADt
NOx50 – 400a0,01 – 0,1a
1.2.3. Waste generation U.K.
BAT 30.In order to prevent waste generation and minimise the amount of solid waste to be disposed of, BAT is to recycle dust from black liquor recovery boiler ESPs to the process.U.K.
Applicability U.K.

Recirculation of dust may be limited due to non-process elements in the dust.

1.2.4. Energy consumption and efficiency U.K.
BAT 31.In order to reduce thermal energy consumption (steam), maximise the benefit of energy carriers used, and to reduce the consumption of electricity, BAT is to apply a combination of the techniques given below.U.K.
Technique
aHigh dry solid content of bark, by use of efficient presses or drying
bHigh efficiency steam boilers, e.g. low flue-gas temperatures
cEffective secondary heating systems
dClosing water systems, including bleach plant
eHigh pulp concentration (middle or high consistency technique)
fHigh efficiency evaporation plant
gRecovery of heat from dissolving tanks e.g. by vent scrubbers
hRecovery and use of the low temperature streams from effluents and other waste heat sources to heat buildings, boiler feedwater and process water
iAppropriate use of secondary heat and secondary condensate
jMonitoring and control of processes, using advanced control systems
kOptimise integrated heat exchanger network
lHeat recovery from the flue-gas from the recovery boiler between the ESP and the fan
mEnsuring as high a pulp consistency as possible in screening and cleaning
nUse of speed control of various large motors
oUse of efficient vacuum pumps
pProper sizing of pipes, pumps and fans
qOptimised tank levels
BAT 32.In order to increase the efficiency of power generation, BAT is to apply a combination of the techniques given below.U.K.
Technique
aHigh black liquor dry solid content (increases boiler efficiency, steam generation and thus electricity generation)
bHigh recovery boiler pressure and temperature; in new recovery boilers the pressure can be at least 100 bars and the temperature 510 °C
cOutlet steam pressure in the back-pressure turbine as low as technically feasible
dCondensing turbine for power production from excess steam
eHigh turbine efficiency
fPreheating feedwater to a temperature close to the boiling temperature
gPreheating the combustion air and fuel charged to the boilers