COMMISSION IMPLEMENTING DECISION (EU) 2017/2117

of 21 November 2017

establishing best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council, for the production of large volume organic chemicals

(notified under document C(2017) 7469)

(Text with EEA relevance)

THE EUROPEAN COMMISSION,

Having regard to the Treaty on the Functioning of the European Union,

Having regard to Directive 2010/75/EU of the European Parliament and of the Council of 24 November 2010 on industrial emissions (integrated pollution prevention and control) (1), and in particular Article 13(5) thereof,

Whereas:

Best available techniques (BAT) conclusions are the reference for setting permit conditions for installations covered by Chapter II of Directive 2010/75/EU and competent authorities should set emission limit values which ensure that, under normal operating conditions, emissions do not exceed the emission levels associated with the best available techniques as laid down in the BAT conclusions.

The forum composed of representatives of Member States, the industries concerned and non-governmental organisations promoting environmental protection, established by Commission Decision of 16 May 2011 (2) , provided the Commission on 5 April 2017 with its opinion on the proposed content of the BAT reference document for the production of large volume organic chemicals. That opinion is publicly available.

The BAT conclusions set out in the Annex to this Decision are the key element of that BAT reference document.

The measures provided for in this Decision are in accordance with the opinion of the Committee established by Article 75(1) of Directive 2010/75/EU,

HAS ADOPTED THIS DECISION:

Article 1

The best available techniques (BAT) conclusions for the production of large volume organic chemicals, as set out in the Annex, are adopted.

Article 2

This Decision is addressed to the Member States.

(1) OJ L 334, 17.12.2010, p. 17.

(2) Commission Decision of 16 May 2011 establishing a forum for the exchange of information pursuant to Article 13 of the Directive 2010/75/EU on industrial emissions (OJ C 146, 17.5.2011, p. 3).

ANNEX

BEST AVAILABLE TECHNIQUES (BAT) CONCLUSIONS FOR THE PRODUCTION OF LARGE VOLUME ORGANIC CHEMICALS

SCOPE

These BAT conclusions concern the production of the following organic chemicals, as specified in Section 4.1 of Annex I to Directive 2010/75/EU:

(a) simple hydrocarbons (linear or cyclic, saturated or unsaturated, aliphatic or aromatic);

(b) oxygen-containing hydrocarbons such as alcohols, aldehydes, ketones, carboxylic acids, esters and mixtures of esters, acetates, ethers, peroxides and epoxy resins;

(c) sulphurous hydrocarbons;

(d) nitrogenous hydrocarbons such as amines, amides, nitrous compounds, nitro compounds or nitrate compounds, nitriles, cyanates, isocyanates;

(e) phosphorus-containing hydrocarbons;

(f) halogenic hydrocarbons;

(g) organometallic compounds;

(k) surface-active agents and surfactants.

These BAT conclusions also cover the production of hydrogen peroxide as specified in Section 4.2(e) of Annex I to Directive 2010/75/EU.

These BAT conclusions cover combustion of fuels in process furnaces/heaters, where this is part of the abovementioned activities.

These BAT conclusions cover production of the aforementioned chemicals in continuous processes where the total production capacity of those chemicals exceeds 20 kt/year.

These BAT conclusions do not address the following:

— combustion of fuels other than in a process furnace/heater or a thermal/catalytic oxidiser; this may be covered by the BAT conclusions for Large Combustion Plants (LCP);

— incineration of waste; this may be covered by the BAT conclusions for Waste Incineration (WI);

— ethanol production taking place on an installation covered by the activity description in Section 6.4(b)(ii) of Annex I to Directive 2010/75/EU or covered as a directly associated activity to such an installation; this may be covered by the BAT conclusions for Food, Drink and Milk Industries (FDM).

Other BAT conclusions which are complementary for the activities covered by these BAT conclusions include:

— Common Waste Water/Waste Gas Treatment/Management Systems in the Chemical Sector (CWW);

— Common Waste Gas Treatment in the Chemical Sector (WGC).

Other BAT conclusions and reference documents which may be of relevance for the activities covered by these BAT conclusions are the following:

— Economics and Cross-media Effects (ECM);

— Emissions from Storage (EFS);

— Energy Efficiency (ENE);

— Industrial Cooling Systems (ICS);

— Large Combustion Plants (LCP);

— Refining of Mineral Oil and Gas (REF);

— Monitoring of Emissions to Air and Water from IED installations (ROM);

— Waste Incineration (WI);

— Waste Treatment (WT).

GENERAL CONSIDERATIONS

Best Available Techniques

The techniques listed and described in these BAT conclusions are neither prescriptive nor exhaustive. Other techniques may be used that ensure at least an equivalent level of environmental protection.

Unless otherwise stated, the BAT conclusions are generally applicable.

Averaging periods and reference conditions for emissions to air

Unless stated otherwise, the emission levels associated with the best available techniques (BAT-AELs) for emissions to air given in these BAT conclusions refer to values of concentration, expressed as mass of emitted substance per volume of waste gas under standard conditions (dry gas at a temperature of 273,15 K, and a pressure of 101,3 kPa), and expressed in the unit mg/Nm3.

Unless stated otherwise, the averaging periods associated with the BAT-AELs for emissions to air are defined as follows.

Type of measurement Averaging period Definition Continuous Daily average Average over a period of 1 day based on valid hourly or half-hourly averages Periodic Average over the sampling period Average of three consecutive measurements of at least 30 minutes each (1) (2)

Where BAT-AELs refer to specific emission loads, expressed as load of emitted substance per unit of production output, the average specific emission loads ls are calculated using Equation 1:

Equation 1:

where:

n = number of measurement periods; ci = average concentration of the substance during ith measurement period; qi = average flow rate during ith measurement period; pi = production output during ith measurement period.

Reference oxygen level

For process furnaces/heaters, the reference oxygen level of the waste gases (OR ) is 3 vol-%.

Conversion to reference oxygen level

The emission concentration at the reference oxygen level is calculated using Equation 2:

Equation 2:

where:

ER = emission concentration at the reference oxygen level OR ; OR = reference oxygen level in vol-%; EM = measured emission concentration; OM = measured oxygen level in vol-%.

Averaging periods for emissions to water

Unless stated otherwise, the averaging periods associated with the environmental performance levels associated with the best available techniques (BAT-AEPLs) for emissions to water expressed in concentrations are defined as follows.

Averaging period Definition Average of values obtained during one month Flow-weighted average value from 24-hour flow-proportional composite samples obtained during 1 month under normal operating conditions (3) Average of values obtained during one year Flow-weighted average value from 24-hour flow-proportional composite samples obtained during 1 year under normal operating conditions (3)

Flow-weighted average concentrations of the parameter (cw ) are calculated using Equation 3:

Equation 3:

where:

n = number of measurement periods; ci = average concentration of the parameter during ith measurement period; qi = average flow rate during ith measurement period.

Where BAT-AEPLs refer to specific emission loads, expressed as load of emitted substance per unit of production output, the average specific emission loads are calculated using Equation 1.

Acronyms and definitions

For the purposes of these BAT conclusions, the following acronyms and definitions apply.

Term used Definition BAT-AEPL Environmental performance level associated with BAT, as described in Commission Implementing Decision 2012/119/EU (4). BAT-AEPLs include emission levels associated with the best available techniques (BAT-AELs) as defined in Article 3(13) of Directive 2010/75/EU BTX Collective term for benzene, toluene and ortho-/meta-/para-xylene or mixtures thereof CO Carbon monoxide Combustion unit Any technical apparatus in which fuels are oxidised in order to use the heat thus generated. Combustion units include boilers, engines, turbines and process furnaces/heaters, but do not include waste gas treatment units (e.g. a thermal/catalytic oxidiser used for the abatement of organic compounds) Continuous measurement Measurement using an ‘automated measuring system’ permanently installed on site Continuous process A process in which the raw materials are fed continuously into the reactor with the reaction products then fed into connected downstream separation and/or recovery units Copper The sum of copper and its compounds, in dissolved or particulate form, expressed as Cu DNT Dinitrotoluene EB Ethylbenzene EDC Ethylene dichloride EG Ethylene glycols EO Ethylene oxide Ethanolamines Collective term for monoethanolamine, diethanolamine and triethanolamine, or mixtures thereof Ethylene glycols Collective term for monoethylene glycol, diethylene glycol and triethylene glycol, or mixtures thereof Existing plant A plant that is not a new plant Existing unit A unit that is not a new unit Flue-gas The exhaust gas exiting a combustion unit I-TEQ International toxic equivalent – derived by using the international toxic equivalence factors, as defined in Annex VI, part 2 to Directive 2010/75/EU Lower olefins Collective term for ethylene, propylene, butylene and butadiene, or mixtures thereof Major plant upgrade A major change in the design or technology of a plant with major adjustments or replacements of the process and/or abatement units and associated equipment MDA Methylene diphenyl diamine MDI Methylene diphenyl diisocyanate MDI plant Plant for the production of MDI from MDA via phosgenation New plant A plant first permitted on the site of the installation following the publication of these BAT conclusions or a complete replacement of a plant following the publication of these BAT conclusions New unit A unit first permitted following the publication of these BAT conclusions or a complete replacement of a unit following the publication of these BAT conclusions NOX precursors Nitrogen-containing compounds (e.g. ammonia, nitrous gases and nitrogen-containing organic compounds) in the input to a thermal treatment that lead to NOX emissions. Elementary nitrogen is not included PCDD/F Polychlorinated dibenzo-dioxins and -furans Periodic measurement Measurement at specified time intervals using manual or automated methods Process furnace/heater Process furnaces or heaters are: — combustion units whose flue-gases are used for the thermal treatment of objects or feed material through direct contact, e.g. in drying processes or chemical reactors; or — combustion units whose radiant and/or conductive heat is transferred to objects or feed material through a solid wall without using an intermediary heat transfer fluid, e.g. furnaces or reactors heating a process stream used in the (petro-)chemical industry such as steam cracker furnaces. It should be noted that, as a consequence of the application of good energy recovery practices, some of the process furnaces/heaters may have an associated steam/electricity generation system. This is considered to be an integral design feature of the process furnace/heater that cannot be considered in isolation. Process off-gas The gas leaving a process which is further treated for recovery and/or abatement NOX The sum of nitrogen monoxide (NO) and nitrogen dioxide (NO2), expressed as NO2 Residues Substances or objects generated by the activities covered by the scope of this document, as waste or by-products RTO Regenerative thermal oxidiser SCR Selective catalytic reduction SMPO Styrene monomer and propylene oxide SNCR Selective non-catalytic reduction SRU Sulphur recovery unit TDA Toluene diamine TDI Toluene diisocyanate TDI plant Plant for the production of TDI from TDA via phosgenation TOC Total organic carbon, expressed as C; includes all organic compounds (in water) Total suspended solids (TSS) Mass concentration of all suspended solids, measured via filtration through glass fibre filters and gravimetry TVOC Total volatile organic carbon; total volatile organic compounds which are measured by a flame ionisation detector (FID) and expressed as total carbon Unit A segment/subpart of a plant in which a specific process or operation is carried out (e.g. reactor, scrubber, distillation column). Units can be new units or existing units Valid hourly or half-hourly average An hourly (or half-hourly) average is considered valid when there is no maintenance or malfunction of the automated measuring system VCM Vinyl chloride monomer VOCs Volatile organic compounds as defined in Article 3(45) of Directive 2010/75/EU

1. GENERAL BAT CONCLUSIONS

The sector-specific BAT conclusions included in Sections 2 to 11 apply in addition to the general BAT conclusions given in this section.

1.1. Monitoring of emissions to air

BAT 1: BAT is to monitor channelled emissions to air from process furnaces/heaters in accordance with EN standards and with at least the minimum frequency given in the table below. If EN standards are not available, BAT is to use ISO, national or other international standards that ensure the provision of data of an equivalent scientific quality. Substance/Parameter Standard(s) (5) Total rated thermal input (MWth) (6) Minimum monitoring frequency (7) Monitoring associated with CO Generic EN standards ≥ 50 Continuous Table 2.1, Table 10.1 EN 15058 10 to < 50 Once every 3 months (8) Dust (9) Generic EN standards and EN 13284-2 ≥ 50 Continuous BAT 5 EN 13284-1 10 to < 50 Once every 3 months (8) NH3 (10) Generic EN standards ≥ 50 Continuous BAT 7, Table 2.1 No EN standard available 10 to < 50 Once every 3 months (8) NOX Generic EN standards ≥ 50 Continuous BAT 4, Table 2.1, Table 10.1 EN 14792 10 to < 50 Once every 3 months (8) SO2 (11) Generic EN standards ≥ 50 Continuous BAT 6 EN 14791 10 to < 50 Once every 3 months (8)

BAT 2: BAT is to monitor channelled emissions to air other than from process furnaces/heaters in accordance with EN standards and with at least the minimum frequency given in the table below. If EN standards are not available, BAT is to use ISO, national or other international standards that ensure the provision of data of an equivalent scientific quality. Substance/Parameter Processes/Sources Standard(s) Minimum monitoring frequency Monitoring associated with Benzene Waste gas from the cumene oxidation unit in phenol production (12) No EN standard available Once every month (13) BAT 57 All other processes/sources (14) BAT 10 Cl2 TDI/MDI (12) No EN standard available Once every month (13) BAT 66 EDC/VCM BAT 76 CO Thermal oxidiser EN 15058 Once every month (13) BAT 13 Lower olefins (decoking) No EN standard available (15) Once every year or once during decoking, if decoking is less frequent BAT 20 EDC/VCM (decoking) BAT 78 Dust Lower olefins (decoking) No EN standard available (16) Once every year or once during decoking, if decoking is less frequent BAT 20 EDC/VCM (decoking) BAT 78 All other processes/sources (14) EN 13284-1 Once every month (13) BAT 11 EDC EDC/VCM No EN standard available Once every month (13) BAT 76 Ethylene oxide Ethylene oxide and ethylene glycols No EN standard available Once every month (13) BAT 52 Formaldehyde Formaldehyde No EN standard available Once every month (13) BAT 45 Gaseous chlorides, expressed as HCl TDI/MDI (12) EN 1911 Once every month (13) BAT 66 EDC/VCM BAT 76 All other processes/sources (14) BAT 12 NH3 Use of SCR or SNCR No EN standard available Once every month (13) BAT 7 NOX Thermal oxidiser EN 14792 Once every month (13) BAT 13 PCDD/F TDI/MDI (17) EN 1948-1, -2, and -3 Once every 6 months (13) BAT 67 PCDD/F EDC/VCM BAT 77 SO2 All processes/sources (14) EN 14791 Once every month (13) BAT 12 Tetrachloromethane TDI/MDI (12) No EN standard available Once every month (13) BAT 66 TVOC TDI/MDI EN 12619 Once every month (13) BAT 66 EO (desorption of CO2 from scrubbing medium) Once every 6 months (13) BAT 51 Formaldehyde Once every month (13) BAT 45 Waste gas from the cumene oxidation unit in phenol production EN 12619 Once every month (13) BAT 57 Waste gas from other sources in phenol production when not combined with other waste gas streams Once every year Waste gas from the oxidation unit in hydrogen peroxide production Once every month (13) BAT 86 EDC/VCM Once every month (13) BAT 76 All other processes/sources (14) Once every month (13) BAT 10 VCM EDC/VCM No EN standard available Once every month (13) BAT 76

1.2. Emissions to air

1.2.1. Emissions to air from process furnaces/heaters

BAT 3: In order to reduce emissions to air of CO and unburnt substances from process furnaces/heaters, BAT is to ensure an optimised combustion. Optimised combustion is achieved by good design and operation of the equipment which includes optimisation of the temperature and residence time in the combustion zone, efficient mixing of the fuel and combustion air, and combustion control. Combustion control is based on the continuous monitoring and automated control of appropriate combustion parameters (e.g. O2, CO, fuel to air ratio, and unburnt substances).

BAT 4: In order to reduce NOX emissions to air from process furnaces/heaters, BAT is to use one or a combination of the techniques given below. Technique Description Applicability a. Choice of fuel See Section 12.3. This includes switching from liquid to gaseous fuels, taking into account the overall hydrocarbon balance The switch from liquid to gaseous fuels may be restricted by the design of the burners in the case of existing plants b. Staged combustion Staged combustion burners achieve lower NOX emissions by staging the injection of either air or fuel in the near burner region. The division of fuel or air reduces the oxygen concentration in the primary burner combustion zone, thereby lowering the peak flame temperature and reducing thermal NOX formation Applicability may be restricted by space availability when upgrading small process furnaces, thus limiting the retrofit of fuel/air staging without reducing capacity For existing EDC crackers, the applicability may be restricted by the design of the process furnace c. Flue-gas recirculation (external) Recirculation of part of the flue-gas to the combustion chamber to replace part of the fresh combustion air, with the effect of reducing the oxygen content and therefore cooling the temperature of the flame For existing process furnaces/heaters, the applicability may be restricted by their design. Not applicable to existing EDC crackers d. Flue-gas recirculation (internal) Recirculation of part of the flue-gas within the combustion chamber to replace part of the fresh combustion air, with the effect of reducing the oxygen content and therefore reducing the temperature of the flame For existing process furnaces/heaters, the applicability may be restricted by their design e. Low-NOX burner (LNB) or ultra-low-NOX burner (ULNB) See Section 12.3 For existing process furnaces/heaters, the applicability may be restricted by their design f. Use of inert diluents ‘Inert’ diluents, e.g. steam, water, nitrogen, are used (either by being premixed with the fuel prior to its combustion or directly injected into the combustion chamber) to reduce the temperature of the flame. Steam injection may increase CO emissions Generally applicable g. Selective catalytic reduction (SCR) See Section 12.1 Applicability to existing process furnaces/heaters may be restricted by space availability h. Selective non-catalytic reduction (SNCR) See Section 12.1 Applicability to existing process furnaces/heaters may be restricted by the temperature window (900–1 050 °C) and the residence time needed for the reaction. Not applicable to EDC crackers BAT-associated emission levels (BAT-AELs): See Table 2.1 and Table 10.1.

BAT 5: In order to prevent or reduce dust emissions to air from process furnaces/heaters, BAT is to use one or a combination of the techniques given below. Technique Description Applicability a. Choice of fuel See Section 12.3. This includes switching from liquid to gaseous fuels, taking into account the overall hydrocarbon balance The switch from liquid to gaseous fuels may be restricted by the design of the burners in the case of existing plants b. Atomisation of liquid fuels Use of high pressure to reduce the droplet size of liquid fuel. Current optimal burner design generally includes steam atomisation Generally applicable c. Fabric, ceramic or metal filter See Section 12.1 Not applicable when only combusting gaseous fuels

BAT 6: In order to prevent or reduce SO2 emissions to air from process furnaces/heaters, BAT is to use one or both of the techniques given below. Technique Description Applicability a. Choice of fuel See Section 12.3. This includes switching from liquid to gaseous fuels, taking into account the overall hydrocarbon balance The switch from liquid to gaseous fuels may be restricted by the design of the burners in the case of existing plants b. Caustic scrubbing See Section 12.1 Applicability may be restricted by space availability

1.2.2. Emissions to air from the use of SCR or SNCR

BAT 7: In order to reduce emissions to air of ammonia which is used in selective catalytic reduction (SCR) or selective non-catalytic reduction (SNCR) for the abatement of NOX emissions, BAT is to optimise the design and/or operation of SCR or SNCR (e.g. optimised reagent to NOX ratio, homogeneous reagent distribution and optimum size of the reagent drops). BAT-associated emission levels (BAT-AELs) for emissions from a lower olefins cracker furnace when SCR or SNCR is used: Table 2.1.

1.2.3. Emissions to air from other processes/sources

1.2.3.1. Techniques to reduce emissions from other processes/sources

BAT 8: In order to reduce the load of pollutants sent to the final waste gas treatment, and to increase resource efficiency, BAT is to use an appropriate combination of the techniques given below for process off-gas streams. Technique Description Applicability a. Recovery and use of excess or generated hydrogen Recovery and use of excess hydrogen or hydrogen generated from chemical reactions (e.g. for hydrogenation reactions). Recovery techniques such as pressure swing adsorption or membrane separation may be used to increase the hydrogen content Applicability may be restricted where the energy demand for recovery is excessive due to the low hydrogen content or when there is no demand for hydrogen b. Recovery and use of organic solvents and unreacted organic raw materials Recovery techniques such as compression, condensation, cryogenic condensation, membrane separation and adsorption may be used. The choice of technique may be influenced by safety considerations, e.g. presence of other substances or contaminants Applicability may be restricted where the energy demand for recovery is excessive due to the low organic content c. Use of spent air The large volume of spent air from oxidation reactions is treated and used as low-purity nitrogen Only applicable where there are available uses for low-purity nitrogen which do not compromise process safety d. Recovery of HCl by wet scrubbing for subsequent use Gaseous HCl is absorbed in water using a wet scrubber, which may be followed by purification (e.g. using adsorption) and/or concentration (e.g. using distillation) (see Section 12.1 for the technique descriptions). The recovered HCl is then used (e.g. as acid or to produce chlorine) Applicability may be restricted in the case of low HCl loads e. Recovery of H2S by regenerative amine scrubbing for subsequent use Regenerative amine scrubbing is used for recovering H2S from process off-gas streams and from the acidic off-gases of sour water stripping units. H2S is then typically converted to elemental sulphur in a sulphur recovery unit in a refinery (Claus process). Only applicable if a refinery is located nearby f. Techniques to reduce solids and/or liquids entrainment See Section 12.1 Generally applicable

BAT 9: In order to reduce the load of pollutants sent to the final waste gas treatment, and to increase energy efficiency, BAT is to send process off-gas streams with a sufficient calorific value to a combustion unit. BAT 8a and 8b have priority over sending process off-gas streams to a combustion unit. Applicability: Sending process off-gas streams to a combustion unit may be restricted due to the presence of contaminants or due to safety considerations.

BAT 10: In order to reduce channelled emissions of organic compounds to air, BAT is to use one or a combination of the techniques given below. Technique Description Applicability a. Condensation See Section 12.1. The technique is generally used in combination with further abatement techniques Generally applicable b. Adsorption See Section 12.1 Generally applicable c. Wet scrubbing See Section 12.1 Only applicable to VOCs that can be absorbed in aqueous solutions d. Catalytic oxidiser See Section 12.1 Applicability may be restricted by the presence of catalyst poisons e. Thermal oxidiser See Section 12.1. Instead of a thermal oxidiser, an incinerator for the combined treatment of liquid waste and waste gas may be used Generally applicable

BAT 11: In order to reduce channelled dust emissions to air, BAT is to use one or a combination of the techniques given below. Technique Description Applicability a. Cyclone See Section 12.1. The technique is used in combination with further abatement techniques Generally applicable b. Electrostatic precipitator See Section 12.1 For existing units, the applicability may be restricted by space availability or safety considerations c. Fabric filter See Section 12.1 Generally applicable d. Two-stage dust filter See Section 12.1 e. Ceramic/metal filter See Section 12.1 f. Wet dust scrubbing See Section 12.1

BAT 12: In order to reduce emissions to air of sulphur dioxide and other acid gases (e.g. HCl), BAT is to use wet scrubbing. Description: For the description of wet scrubbing, see Section 12.1

1.2.3.2. Techniques to reduce emissions from a thermal oxidiser

BAT 13: In order to reduce emissions to air of NOX, CO, and SO2 from a thermal oxidiser, BAT is to use an appropriate combination of the techniques given below. Technique Description Main pollutant targeted Applicability a. Removal of high levels of NOX precursors from the process off-gas streams Remove (if possible, for reuse) high levels of NOX precursors prior to thermal treatment, e.g. by scrubbing, condensation or adsorption NOX Generally applicable b. Choice of support fuel See Section 12.3 NOX, SO2 Generally applicable c. Low-NOX burner (LNB) See Section 12.1 NOX Applicability to existing units may be restricted by design and/or operational constraints d. Regenerative thermal oxidiser (RTO) See Section 12.1 NOX Applicability to existing units may be restricted by design and/or operational constraints e. Combustion optimisation Design and operational techniques used to maximise the removal of organic compounds, while minimising emissions to air of CO and NOX (e.g. by controlling combustion parameters such as temperature and residence time) CO, NOX Generally applicable f. Selective catalytic reduction (SCR) See Section 12.1 NOX Applicability to existing units may be restricted by space availability g. Selective non-catalytic reduction (SNCR) See Section 12.1 NOX Applicability to existing units may be restricted by the residence time needed for the reaction

1.3. Emissions to water

BAT 14: In order to reduce the waste water volume, the pollutant loads discharged to a suitable final treatment (typically biological treatment), and emissions to water, BAT is to use an integrated waste water management and treatment strategy that includes an appropriate combination of process-integrated techniques, techniques to recover pollutants at source, and pretreatment techniques, based on the information provided by the inventory of waste water streams specified in the CWW BAT conclusions.

1.4. Resource efficiency

BAT 15: In order to increase resource efficiency when using catalysts, BAT is to use a combination of the techniques given below. Technique Description a. Catalyst selection Select the catalyst to achieve the optimal balance between the following factors: — catalyst activity; — catalyst selectivity; — catalyst lifetime (e.g. vulnerability to catalyst poisons); — use of less toxic metals. b. Catalyst protection Techniques used upstream of the catalyst to protect it from poisons (e.g. raw material pretreatment) c. Process optimisation Control of reactor conditions (e.g. temperature, pressure) to achieve the optimal balance between conversion efficiency and catalyst lifetime d. Monitoring of catalyst performance Monitoring of the conversion efficiency to detect the onset of catalyst decay using suitable parameters (e.g. the heat of reaction and the CO2 formation in the case of partial oxidation reactions)

BAT 16: In order to increase resource efficiency, BAT is to recover and reuse organic solvents. Description: Organic solvents used in processes (e.g. chemical reactions) or operations (e.g. extraction) are recovered using appropriate techniques (e.g. distillation or liquid phase separation), purified if necessary (e.g. using distillation, adsorption, stripping or filtration) and returned to the process or operation. The amount recovered and reused is process-specific.

1.5. Residues

BAT 17: In order to prevent or, where that is not practicable, to reduce the amount of waste being sent for disposal, BAT is to use an appropriate combination of the techniques given below. Technique Description Applicability Techniques to prevent or reduce the generation of waste a. Addition of inhibitors to distillation systems Selection (and optimisation of dosage) of polymerisation inhibitors that prevent or reduce the generation of residues (e.g. gums or tars). The optimisation of dosage may need to take into account that it can lead to higher nitrogen and/or sulphur content in the residues which could interfere with their use as a fuel Generally applicable b. Minimisation of high-boiling residue formation in distillation systems Techniques that reduce temperatures and residence times (e.g. packing instead of trays to reduce the pressure drop and thus the temperature; vacuum instead of atmospheric pressure to reduce the temperature) Only applicable to new distillation units or major plant upgrades Techniques to recover materials for reuse or recycling c. Material recovery (e.g. by distillation, cracking) Materials (i.e. raw materials, products, and by-products) are recovered from residues by isolation (e.g. distillation) or conversion (e.g. thermal/catalytic cracking, gasification, hydrogenation) Only applicable where there are available uses for these recovered materials d. Catalyst and adsorbent regeneration Regeneration of catalysts and adsorbents, e.g. using thermal or chemical treatment Applicability may be restricted where regeneration results in significant cross-media effects. Techniques to recover energy e. Use of residues as a fuel Some organic residues, e.g. tar, can be used as fuels in a combustion unit Applicability may be restricted by the presence of certain substances in the residues, making them unsuitable to use in a combustion unit and requiring disposal

1.6. Other than normal operating conditions

BAT 18: In order to prevent or reduce emissions from equipment malfunctions, BAT is to use all of the techniques given below. Technique Description Applicability a. Identification of critical equipment Equipment critical to the protection of the environment (‘critical equipment’) is identified on the basis of a risk assessment (e.g. using a Failure Mode and Effects Analysis) Generally applicable b. Asset reliability programme for critical equipment A structured programme to maximise equipment availability and performance which includes standard operating procedures, preventive maintenance (e.g. against corrosion), monitoring, recording of incidents, and continuous improvements Generally applicable c. Back-up systems for critical equipment Build and maintain back-up systems, e.g. vent gas systems, abatement units Not applicable if appropriate equipment availability can be demonstrated using technique b.

BAT 19: In order to prevent or reduce emissions to air and water occurring during other than normal operating conditions, BAT is to implement measures commensurate with the relevance of potential pollutant releases for: (i) start-up and shutdown operations; (ii) other circumstances (e.g. regular and extraordinary maintenance work and cleaning operations of the units and/or of the waste gas treatment system) including those that could affect the proper functioning of the installation.

2. BAT CONCLUSIONS FOR LOWER OLEFINS PRODUCTION

The BAT conclusions in this section apply to the production of lower olefins using the steam cracking process, and apply in addition to the general BAT conclusions given in Section 1.

2.1. Emissions to air

2.1.1. BAT-AELs for emissions to air from a lower olefins cracker furnace

Table 2.1

BAT-AELs for emissions to air of NOX and NH3 from a lower olefins cracker furnace

Parameter BAT-AELs (18) (19) (20) (daily average or average over the sampling period) (mg/Nm3, at 3 vol-% O2) New furnace Existing furnace NOX 60–100 70–200 NH3 < 5–15 (21)

The associated monitoring is in BAT 1.

2.1.2. Techniques to reduce emissions from decoking

BAT 20: In order to reduce emissions to air of dust and CO from the decoking of the cracker tubes, BAT is to use an appropriate combination of the techniques to reduce the frequency of decoking given below and one or a combination of the abatement techniques given below. Technique Description Applicability Techniques to reduce the frequency of decoking a. Tube materials that retard coke formation Nickel present at the surface of the tubes catalyses coke formation. Employing materials that have lower nickel levels, or coating the interior tube surface with an inert material, can therefore retard the rate of coke build-up Only applicable to new units or major plant upgrades b. Doping of the raw material feed with sulphur compounds As nickel sulphides do not catalyse coke formation, doping the feed with sulphur compounds when they are not already present at the desired level can also help retard the build-up of coke, as this will promote the passivation of the tube surface Generally applicable c. Optimisation of thermal decoking Optimisation of operating conditions, i.e. airflow, temperature and steam content across the decoking cycle, to maximise coke removal Generally applicable Abatement techniques d. Wet dust scrubbing See Section 12.1 Generally applicable e. Dry cyclone See Section 12.1 Generally applicable f. Combustion of decoking waste gas in process furnace/heater The decoking waste gas stream is passed through the process furnace/heater during decoking where the coke particles (and CO) are further combusted Applicability for existing plants may be restricted by the design of the pipework systems or fire-duty restrictions

2.2. Emissions to water

BAT 21: In order to prevent or reduce the amount of organic compounds and waste water discharged to waste water treatment, BAT is to maximise the recovery of hydrocarbons from the quench water of the primary fractionation stage and reuse the quench water in the dilution steam generation system. Description: The technique consists of ensuring an effective separation of organic and aqueous phases. The recovered hydrocarbons are recycled to the cracker or used as raw materials in other chemical processes. Organic recovery can be enhanced, e.g. through the use of steam or gas stripping, or the use of a reboiler. Treated quench water is reused within the dilution steam generation system. A quench water purge stream is discharged to downstream final waste water treatment to prevent the build-up of salts in the system.

BAT 22: In order to reduce the organic load discharged to waste water treatment from the spent caustic scrubber liquor originating from the removal of H2S from the cracked gases, BAT is to use stripping. Description: For the description of stripping see Section 12.2. The stripping of scrubber liquors is carried out using a gaseous stream, which is then combusted (e.g. in the cracker furnace).

BAT 23: In order to prevent or reduce the amount of sulphides discharged to waste water treatment from the spent caustic scrubber liquor originating from the removal of acid gases from the cracked gases, BAT is to use one or a combination of the techniques given below. Technique Description Applicability a. Use of low-sulphur raw materials in the cracker feed Use of raw materials that have a low sulphur content or have been desulphurised Applicability may be restricted by a need for sulphur doping to reduce coke build-up b. Maximisation of the use of amine scrubbing for the removal of acid gases The scrubbing of the cracked gases with a regenerative (amine) solvent to remove acid gases, mainly H2S, to reduce the load on the downstream caustic scrubber Not applicable if the lower olefin cracker is located far away from an SRU. Applicability for existing plants may be restricted by the capacity of the SRU c. Oxidation Oxidation of sulphides present in the spent scrubbing liquor to sulphates, e.g. using air at elevated pressure and temperature (i.e. wet air oxidation) or an oxidising agent such as hydrogen peroxide Generally applicable

3. BAT CONCLUSIONS FOR AROMATICS PRODUCTION

The BAT conclusions in this section apply to the production of benzene, toluene, ortho-, meta- and para-xylene (commonly known as BTX aromatics) and cyclohexane from the pygas by-product of steam crackers and from reformate/naphtha produced in catalytic reformers; and apply in addition to the general BAT conclusions given in Section 1.

3.1. Emissions to air

BAT 24: In order to reduce the organic load from process off-gases sent to the final waste gas treatment and to increase resource efficiency, BAT is to recover organic materials by using BAT 8b. or, where that is not practicable, to recover energy from these process off-gases (see also BAT 9).

BAT 25: In order to reduce emissions to air of dust and organic compounds from the regeneration of hydrogenation catalyst, BAT is to send the process off-gas from catalyst regeneration to a suitable treatment system. Description: The process off-gas is sent to wet or dry dust abatement devices to remove dust and then to a combustion unit or a thermal oxidiser to remove organic compounds in order to avoid direct emissions to air or flaring. The use of decoking drums alone is not sufficient.

3.2. Emissions to water

BAT 26: In order to reduce the amount of organic compounds and waste water discharged from aromatic extraction units to waste water treatment, BAT is either to use dry solvents or to use a closed system for the recovery and reuse of water when wet solvents are used.

BAT 27: In order to reduce the waste water volume and the organic load discharged to waste water treatment, BAT is to use an appropriate combination of the techniques given below. Technique Description Applicability a. Water-free vacuum generation Use mechanical pumping systems in a closed circuit procedure, discharging only a small amount of water as blowdown, or use dry-running pumps. In some cases, waste-water-free vacuum generation can be achieved by use of the product as a barrier liquid in a mechanical vacuum pump, or by use of a gas stream from the production process Generally applicable b. Source segregation of aqueous effluents Aqueous effluents from aromatics plants are segregated from waste water from other sources in order to facilitate the recovery of raw materials or products For existing plants, the applicability may be restricted by site-specific drainage systems c. Liquid phase separation with recovery of hydrocarbons Separation of organic and aqueous phases with appropriate design and operation (e.g. sufficient residence time, phase boundary detection and control) to prevent any entrainment of undissolved organic material Generally applicable d Stripping with recovery of hydrocarbons See Section 12.2. Stripping can be used on individual or combined streams Applicability may be restricted when the concentration of hydrocarbons is low e. Reuse of water With further treatment of some waste water streams, water from stripping can be used as process water or as boiler feed water, replacing other sources of water Generally applicable

3.3. Resource efficiency

BAT 28: In order to use resources efficiently, BAT is to maximise the use of co-produced hydrogen, e.g. from dealkylation reactions, as a chemical reagent or fuel by using BAT 8a. or, where that is not practicable, to recover energy from these process vents (see BAT 9).

3.4. Energy efficiency

BAT 29: In order to use energy efficiently when using distillation, BAT is to use one or a combination of the techniques given below. Technique Description Applicability a. Distillation optimisation For each distillation column, the number of trays, reflux ratio, feed location and, for extractive distillations, the solvents to feed ratio are optimised Applicability to existing units may be restricted by design, space availability and/or operational constraints b. Recovery of heat from column overhead gaseous stream Reuse condensation heat from the toluene and the xylene distillation column to supply heat elsewhere in the installation c. Single extractive distillation column In a conventional extractive distillation system, the separation would require a sequence of two separation steps (i.e. main distillation column with side column or stripper). In a single extractive distillation column, the separation of the solvent is carried out in a smaller distillation column that is incorporated into the column shell of the first column Only applicable to new plants or major plant upgrades. Applicability may be restricted for smaller capacity units as operability may be constrained by combining a number of operations into one piece of equipment d. Distillation column with a dividing wall In a conventional distillation system, the separation of a three-component mixture into its pure fractions requires a direct sequence of at least two distillation columns (or main columns with side columns). With a dividing wall column, separation can be carried out in just one piece of apparatus e. Thermally coupled distillation If distillation is carried out in two columns, energy flows in both columns can be coupled. The steam from the top of the first column is fed to a heat exchanger at the base of the second column Only applicable to new plants or major plant upgrades. Applicability depends on the set-up of the distillation columns and process conditions, e.g. working pressure

3.5. Residues

BAT 30: In order to prevent or reduce the amount of spent clay being sent for disposal, BAT is to use one or both of the techniques given below. Technique Description Applicability a. Selective hydrogenation of reformate or pygas Reduce the olefin content of reformate or pygas by hydrogenation. With fully hydrogenated raw materials, clay treaters have longer operating cycles Only applicable to plants using raw materials with a high olefin content b. Clay material selection Use a clay that lasts as long as possible for its given conditions (i.e. having surface/structural properties that increase the operating cycle length), or use a synthetic material that has the same function as the clay but that can be regenerated Generally applicable

4. BAT CONCLUSIONS FOR ETHYLBENZENE AND STYRENE MONOMER PRODUCTION

The BAT conclusions in this section apply to the production of ethlybenzene using either the zeolite or AlCl3 catalysed alkylation process; and the production of styrene monomer either by ethylbenzene dehydrogenation or co-production with propylene oxide; and apply in addition to the general BAT conclusions given in Section 1.

4.1. Process selection

BAT 31: In order to prevent or reduce emissions to air of organic compounds and acid gases, the generation of waste water and the amount of waste being sent for disposal from the alkylation of benzene with ethylene, BAT for new plants and major plant upgrades is to use the zeolite catalyst process.

4.2. Emissions to air

BAT 32: In order to reduce the load of HCl sent to the final waste gas treatment from the alkylation unit in the AlCl3-catalysed ethylbenzene production process, BAT is to use caustic scrubbing. Description: For the description of caustic scrubbing, see Section 12.1. Applicability: Only applicable to existing plants using the AlCl3 catalysed ethylbenzene production process.

BAT 33: In order to reduce the load of dust and HCl sent to the final waste gas treatment from catalyst replacement operations in the AlCl3-catalysed ethylbenzene production process, BAT is to use wet scrubbing and then use the spent scrubbing liquor as wash water in the post-alkylation reactor wash section. Description: For the description of wet scrubbing, see Section 12.1.

BAT 34: In order to reduce the organic load sent to the final waste gas treatment from the oxidation unit in the SMPO production process, BAT is to use one or a combination of the techniques given below. Technique Description Applicability a. Techniques to reduce liquids entrainment See Section 12.1 Generally applicable b. Condensation See Section 12.1 Generally applicable c. Adsorption See Section 12.1 Generally applicable d. Scrubbing See Section 12.1. Scrubbing is carried out with a suitable solvent (e.g. the cool, recirculated ethylbenzene) to absorb ethylbenzene, which is recycled to the reactor For existing plants, the use of the recirculated ethylbenzene stream may be restricted by the plant design

BAT 35: In order to reduce emissions of organic compounds to air from the acetophenone hydrogenation unit in the SMPO production process, during other than normal operating conditions (such as start-up events), BAT is to send the process off-gas to a suitable treatment system.

4.3. Emissions to water

BAT 36: In order to reduce waste water generation from ethylbenzene dehydrogenation and to maximise the recovery of organic compounds, BAT is to use an appropriate combination of the techniques given below. Technique Description Applicability a. Optimised liquid phase separation Separation of organic and aqueous phases with appropriate design and operation (e.g. sufficient residence time, phase boundary detection and control) to prevent any entrainment of undissolved organic material Generally applicable b. Steam stripping See Section 12.2 Generally applicable c. Adsorption See Section 12.2 Generally applicable d. Reuse of water Condensates from the reaction can be used as process water or as boiler feed after steam stripping (see technique b.) and adsorption (see technique c.) Generally applicable

BAT 37: In order to reduce emissions to water of organic peroxides from the oxidation unit in the SMPO production process and to protect the downstream biological waste water treatment plant, BAT is to pretreat waste water containing organic peroxides using hydrolysis before it is combined with other waste water streams and discharged to the final biological treatment. Description: For the description of hydrolysis see Section 12.2.

4.4. Resource efficiency

BAT 38: In order to recover organic compounds from ethylbenzene dehydrogenation prior to the recovery of hydrogen (see BAT 39), BAT is to use one or both of the techniques given below. Technique Description Applicability a. Condensation See Section 12.1 Generally applicable b. Scrubbing See Section 12.1. The absorbent consists of commercial organic solvents (or tar from ethylbenzene plants) (see BAT 42b). VOCs are recovered by stripping of the scrubber liquor

BAT 39: In order to increase resource efficiency, BAT is to recover the co-produced hydrogen from ethylbenzene dehydrogenation, and to use it either as a chemical reagent or to combust the dehydrogenation off-gas as a fuel (e.g. in the steam superheater).

BAT 40: In order to increase the resource efficiency of the acetophenone hydrogenation unit in the SMPO production process, BAT is to minimise excess hydrogen or to recycle hydrogen by using BAT 8a. If BAT 8a is not applicable, BAT is to recover energy (see BAT 9).

4.5. Residues

BAT 41: In order to reduce the amount of waste being sent for disposal from spent catalyst neutralisation in the AlCl3-catalysed ethylbenzene production process, BAT is to recover residual organic compounds by stripping and then concentrate the aqueous phase to give a usable AlCl3 by-product. Description: Steam stripping is first used to remove VOCs, then the spent catalyst solution is concentrated by evaporation to give a usable AlCl3 by-product. The vapour phase is condensed to give a HCl solution that is recycled into the process.

BAT 42: In order to prevent or reduce the amount of waste tar being sent for disposal from the distillation unit of ethylbenzene production, BAT is to use one or a combination of the techniques given below. Technique Description Applicability a. Material recovery (e.g. by distillation, cracking) See BAT 17c Only applicable where there are available uses for these recovered materials b. Use of tar as an absorbent for scrubbing See section 12.1. Use the tar as an absorbent in the scrubbers used in styrene monomer production by ethylbenzene dehydrogenation, instead of commercial organic solvents (see BAT 38b). The extent to which tar can be used depends on the scrubber capacity Generally applicable c. Use of tar as a fuel See BAT 17e Generally applicable

BAT 43: In order to reduce the generation of coke (which is both a catalyst poison and a waste) from units producing styrene by ethylbenzene dehydrogenation, BAT is to operate at the lowest possible pressure that is safe and practicable.

BAT 44: In order to reduce the amount of organic residues being sent for disposal from styrene monomer production including its co-production with propylene oxide, BAT is to use one or a combination of the techniques given below. Technique Description Applicability a. Addition of inhibitors to distillation systems See BAT 17a Generally applicable b. Minimisation of high-boiling residue formation in distillation systems See BAT 17b Only applicable to new distillation units or major plant upgrades c. Use of residues as a fuel See BAT 17e Generally applicable

5. BAT CONCLUSIONS FOR FORMALDEHYDE PRODUCTION

The BAT conclusions in this section apply in addition to the general BAT conclusions given in Section 1.

5.1. Emissions to air

BAT 45: In order to reduce emissions of organic compounds to air from formaldehyde production and to use energy efficiently, BAT is to use one of the techniques given below. Technique Description Applicability a. Send the waste gas stream to a combustion unit See BAT 9 Only applicable to the silver process b. Catalytic oxidiser with energy recovery See Section 12.1. Energy is recovered as steam Only applicable to the metal oxide process. The ability to recover energy may be restricted in small stand-alone plants c. Thermal oxidiser with energy recovery See Section 12.1. Energy is recovered as steam Only applicable to the silver process

Table 5.1 BAT-AELs for emissions of TVOC and formaldehyde to air from formaldehyde production Parameter BAT-AEL (daily average or average over the sampling period) (mg/Nm3, no correction for oxygen content) TVOC < 5–30 (22) Formaldehyde 2–5 The associated monitoring is in BAT 2.

5.2. Emissions to water

BAT 46: In order to prevent or reduce waste water generation (e.g. from cleaning, spills and condensates) and the organic load discharged to further waste water treatment, BAT is to use one or both of the techniques given below. Technique Description Applicability a. Reuse of water Aqueous streams (e.g. from cleaning, spills and condensates) are recirculated into the process mainly to adjust the formaldehyde product concentration. The extent to which water can be reused depends on the desired formaldehyde concentration Generally applicable b. Chemical pretreatment Conversion of formaldehyde into other substances which are less toxic, e.g. by addition of sodium sulphite or by oxidation Only applicable to effluents which, due to their formaldehyde content, could have a negative effect on the downstream biological waste water treatment

5.3. Residues

BAT 47: In order to reduce the amount of paraformaldehyde-containing waste being sent for disposal, BAT is to use one or a combination of the techniques given below. Technique Description Applicability a. Minimisation of paraformaldehyde generation The formation of paraformaldehyde is minimised by improved heating, insulation and flow circulation Generally applicable b. Material recovery Paraformaldehyde is recovered by dissolution in hot water where it undergoes hydrolysis and depolymerisation to give a formaldehyde solution, or is reused directly in other processes Not applicable when the recovered paraformaldehyde cannot be used due to its contamination c. Use of residues as a fuel Paraformaldehyde is recovered and used as a fuel Only applicable when technique b. cannot be applied

6. BAT CONCLUSIONS FOR ETHYLENE OXIDE AND ETHYLENE GLYCOLS PRODUCTION

The BAT conclusions in this section apply in addition to the general BAT conclusions given in Section 1.

6.1. Process selection

BAT 48: In order to reduce the consumption of ethylene and emissions to air of organic compounds and CO2, BAT for new plants and major plant upgrades is to use oxygen instead of air for the direct oxidation of ethylene to ethylene oxide.

6.2. Emissions to air

BAT 49: In order to recover ethylene and energy and to reduce emissions of organic compounds to air from the EO plant, BAT is to use both of the techniques given below. Technique Description Applicability Techniques to recover organic material for reuse or recycling a. Use of pressure swing adsorption or membrane separation to recover ethylene from the inerts purge With the pressure swing adsorption technique, the target gas (in this case ethylene) molecules are adsorbed on a solid (e.g. molecular sieve) at high pressure, and subsequently desorbed in more concentrated form at lower pressure for reuse or recycling. For membrane separation, see Section 12.1 Applicability may be restricted when the energy demand is excessive due to a low ethylene mass flow Energy recovery techniques b. Send the inerts purge stream to a combustion unit See BAT 9 Generally applicable

BAT 50: In order to reduce the consumption of ethylene and oxygen and to reduce CO2 emissions to air from the EO unit, BAT is to use a combination of the techniques in BAT 15 and to use inhibitors. Description: The addition of small amounts of an organochlorine inhibitor (such as ethylchloride or dichloroethane) to the reactor feed in order to reduce the proportion of ethylene that is fully oxidised to carbon dioxide. Suitable parameters for the monitoring of catalyst performance include the heat of reaction and the CO2 formation per tonne of ethylene feed.

BAT 51: In order to reduce emissions of organic compounds to air from the desorption of CO2 from the scrubbing medium used in the EO plant, BAT is to use a combination of the techniques given below. Technique Description Applicability Process-integrated techniques a. Staged CO2 desorption The technique consists of conducting the depressurisation necessary to liberate the carbon dioxide from the absorption medium in two steps rather than one. This allows an initial hydrocarbon-rich stream to be isolated for potential recirculation, leaving a relatively clean carbon dioxide stream for further treatment. Only applicable to new plants or major plant upgrades Abatement techniques b. Catalytic oxidiser See Section 12.1 Generally applicable c. Thermal oxidiser See Section 12.1 Generally applicable

Table 6.1 BAT-AEL for emissions of organic compounds to air from the desorption of CO2 from the scrubbing medium used in the EO plant Parameter BAT-AEL TVOC 1–10 g/t of EO produced (23) (24) (25) The associated monitoring is in BAT 2.

BAT 52: In order to reduce EO emissions to air, BAT is to use wet scrubbing for waste gas streams containing EO. Description: For the description of wet scrubbing, see Section 12.1. Scrubbing with water to remove EO from waste gas streams before direct release or before further abatement of organic compounds.

BAT 53: In order to prevent or reduce emissions of organic compounds to air from cooling of the EO absorbent in the EO recovery unit, BAT is to use one of the techniques given below. Technique Description Applicability a. Indirect cooling Use indirect cooling systems (with heat exchangers) instead of open cooling systems Only applicable to new plants or major plant upgrades b. Complete EO removal by stripping Maintain appropriate operating conditions and use online monitoring of the EO stripper operation to ensure that all EO is stripped out; and provide adequate protection systems to avoid EO emissions during other than normal operating conditions Only applicable when technique a. cannot be applied

6.3. Emissions to water

BAT 54: In order to reduce the waste water volume and to reduce the organic load discharged from the product purification to final waste water treatment, BAT is to use one or both of the techniques given below. Technique Description Applicability a. Use of the purge from the EO plant in the EG plant The purge streams from the EO plant are sent to the EG process and not discharged as waste water. The extent to which the purge can be reused in the EG process depends on EG product quality considerations. Generally applicable b. Distillation Distillation is a technique used to separate compounds with different boiling points by partial evaporation and recondensation. The technique is used in EO and EG plants to concentrate aqueous streams to recover glycols or enable their disposal (e.g. by incineration, instead of their discharge as waste water) and to enable the partial reuse/recycling of water. Only applicable to new plants or major plant upgrades

6.4. Residues

BAT 55: In order to reduce the amount of organic waste being sent for disposal from the EO and EG plant, BAT is to use a combination of the techniques given below. Technique Description Applicability a. Hydrolysis reaction optimisation Optimisation of the water to EO ratio to both achieve lower co-production of heavier glycols and avoid excessive energy demand for the dewatering of glycols. The optimum ratio depends on the target output of di- and triethylene glycols Generally applicable b. Isolation of by-products at EO plants for use For EO plants, the concentrated organic fraction obtained after the dewatering of the liquid effluent from EO recovery is distilled to give valuable short-chain glycols and a heavier residue Only applicable to new plants or major plant upgrades c. Isolation of by-products at EG plants for use For EG plants, the longer chain glycols fraction can either be used as such or further fractionated to yield valuable glycols Generally applicable

7. BAT CONCLUSIONS FOR PHENOL PRODUCTION

The BAT conclusions in this section apply to the production of phenol from cumene, and apply in addition to the general BAT conclusions given in Section 1.

7.1. Emissions to air

BAT 56: In order to recover raw materials and to reduce the organic load sent from the cumene oxidation unit to the final waste gas treatment, BAT is to use a combination of the techniques given below. Technique Description Applicability Process-integrated techniques a. Techniques to reduce liquids entrainment See Section 12.1 Generally applicable Techniques to recover organic material for reuse b. Condensation See Section 12.1 Generally applicable c. Adsorption (regenerative) See Section 12.1 Generally applicable

BAT 57: In order to reduce emissions of organic compounds to air, BAT is to use technique d given below for waste gas from the cumene oxidation unit. For any other individual or combined waste gas streams, BAT is to use one or a combination of the techniques given below. Technique Description Applicability a. Send the waste gas stream to a combustion unit See BAT 9 Only applicable where there are available uses for the waste gas as gaseous fuel b. Adsorption See Section 12.1 Generally applicable c. Thermal oxidiser See Section 12.1 Generally applicable d. Regenerative thermal oxidiser (RTO) See Section 12.1 Generally applicable

Table 7.1 BAT-AELs for emissions of TVOC and benzene to air from the production of phenol Parameter Source BAT-AEL (daily average or average over the sampling period) (mg/Nm3, no correction for oxygen content) Conditions Benzene Cumene oxidation unit < 1 The BAT-AEL applies if the emission exceeds 1 g/h TVOC 5–30 — The associated monitoring is in BAT 2.

7.2. Emissions to water

BAT 58: In order to reduce emissions to water of organic peroxides from the oxidation unit and, if necessary, to protect the downstream biological waste water treatment plant, BAT is to pretreat waste water containing organic peroxides using hydrolysis before it is combined with other waste water streams and discharged to the final biological treatment. Description: For the description of hydrolysis, see Section 12.2. Waste water (mainly from the condensers and the adsorber regeneration, after phase separation) is treated thermally (at temperatures above 100 °C and a high pH) or catalytically to decompose organic peroxides to non-ecotoxic and more readily biodegradable compounds. Table 7.2 BAT-AEPL for organic peroxides at the outlet of the peroxides decomposition unit Parameter BAT-AEPL (average value from at least three spot samples taken at intervals of at least half an hour) Associated monitoring Total organic peroxides, expressed as cumene hydroperoxide < 100 mg/l No EN standard available. The minimum monitoring frequency is once every day and may be reduced to four times per year if adequate performance of the hydrolysis is demonstrated by controlling the process parameters (e.g. pH, temperature and residence time)

BAT 59: In order to reduce the organic load discharged from the cleavage unit and the distillation unit to further waste water treatment, BAT is to recover phenol and other organic compounds (e.g. acetone) using extraction followed by stripping. Description: Recovery of phenol from phenol-containing waste water streams by adjustment of the pH to < 7, followed by extraction with a suitable solvent and stripping of the waste water to remove residual solvent and other low-boiling compounds (e.g. acetone). For the description of the treatment techniques, see Section 12.2.

7.3. Residues

BAT 60: In order to prevent or reduce the amount of tar being sent for disposal from phenol purification, BAT is to use one or both of the techniques given below. Technique Description Applicability a. Material recovery (e.g. by distillation, cracking) See BAT 17c. Use distillation to recover cumene, α-methylstyrene phenol, etc. Generally applicable b. Use of tar as a fuel See BAT 17e. Generally applicable

8. BAT CONCLUSIONS FOR ETHANOLAMINES PRODUCTION

The BAT conclusions in this section apply in addition to the general BAT conclusions given in Section 1.

8.1. Emissions to air

BAT 61: In order to reduce ammonia emissions to air and to reduce the consumption of ammonia from the aqueous ethanolamines production process, BAT is to use a multistage wet scrubbing system. Description: For the description of wet scrubbing, see Section 12.1. Unreacted ammonia is recovered from the off-gas of the ammonia stripper and also from the evaporation unit by wet scrubbing in at least two stages followed by ammonia recycling into the process.

8.2. Emissions to water

BAT 62: In order to prevent or reduce emissions of organic compounds to air and emissions to water of organic substances from the vacuum systems, BAT is to use one or a combination of the techniques given below. Technique Description Applicability a. Water-free vacuum generation Use of dry-running pumps, e.g. positive displacement pumps Applicability to existing plants may be restricted by design and/or operational constraints b. Use of water ring vacuum pumps with recirculation of the ring water The water used as the sealant liquid of the pump is recirculated to the pump casing via a closed loop with only small purges, so that waste water generation is minimised Only applicable when technique a. cannot be applied. Not applicable for triethanolamine distillation c. Reuse of aqueous streams from vacuum systems in the process Return aqueous streams from water ring pumps or steam ejectors to the process for recovery of organic material and reuse of the water. The extent to which water can be reused in the process is restricted by the water demand of the process Only applicable when technique a. cannot be applied d. Condensation of organic compounds (amines) upstream of vacuum systems See Section 12.1 Generally applicable

8.3. Raw material consumption

BAT 63: In order to use ethylene oxide efficiently, BAT is to use a combination of the techniques given below. Technique Description Applicability a. Use of excess ammonia Maintaining a high level of ammonia in the reaction mixture is an effective way of ensuring that all the ethylene oxide is converted into products Generally applicable b. Optimisation of the water content in the reaction Water is used to accelerate the main reactions without changing the product distribution and without significant side reactions with ethylene oxide to glycols Only applicable for the aqueous process c. Optimise the process operating conditions Determine and maintain the optimum operating conditions (e.g. temperature, pressure, residence time) to maximise the conversion of ethylene oxide to the desired mix of mono-, di-, triethanolamines Generally applicable

9. BAT CONCLUSIONS FOR TOLUENE DIISOCYANATE (TDI) AND METHYLENE DIPHENYL DIISOCYANATE (MDI) PRODUCTION

The BAT conclusions in this section cover the production of:

— dinitrotoluene (DNT) from toluene;

— toluene diamine (TDA) from DNT;

— TDI from TDA;

— methylene diphenyl diamine (MDA) from aniline;

— MDI from MDA;

and apply in addition to the general BAT conclusions given in Section 1.

9.1. Emissions to air

BAT 64: In order to reduce the load of organic compounds, NOX, NOX precursors and SOX sent to the final waste gas treatment (see BAT 66) from DNT, TDA and MDA plants, BAT is to use a combination of the techniques given below. Technique Description Applicability a. Condensation See Section 12.1 Generally applicable b. Wet scrubbing See Section 12.1. In many cases, scrubbing efficiency is enhanced by the chemical reaction of the absorbed pollutant (partial oxidation of NOX with recovery of nitric acid, removal of acids with caustic solution, removal of amines with acidic solutions, reaction of aniline with formaldehyde in caustic solution) c. Thermal reduction See Section 12.1 Applicability to existing units may be restricted by space availability d. Catalytic reduction See Section 12.1

BAT 65: In order to reduce the load of HCl and phosgene sent to the final waste gas treatment and to increase resource efficiency, BAT is to recover HCl and phosgene from the process off-gas streams of TDI and/or MDI plants by using an appropriate combination of the techniques given below. Technique Description Applicability a. Absorption of HCl by wet scrubbing See BAT 8d. Generally applicable b. Absorption of phosgene by scrubbing See Section 12.1. The excess phosgene is absorbed using an organic solvent and returned to the process Generally applicable c. HCl/phosgene condensation See Section 12.1 Generally applicable

BAT 66: In order to reduce emissions to air of organic compounds (including chlorinated hydrocarbons), HCl and chlorine, BAT is to treat combined waste gas streams using a thermal oxidiser followed by caustic scrubbing. Description: The individual waste gas streams from DNT, TDA, TDI, MDA and MDI plants are combined to one or several waste gas streams for treatment. (See Section 12.1 for the descriptions of thermal oxidiser and scrubbing.) Instead of a thermal oxidiser, an incinerator may be used for the combined treatment of liquid waste and the waste gas. Caustic scrubbing is wet scrubbing with caustic added to improve the HCl and chlorine removal efficiency. Table 9.1 BAT-AELs for emissions of TVOC, tetrachloromethane, Cl2, HCl and PCDD/F to air from the TDI/MDI process Parameter BAT-AEL (mg/Nm3, no correction for oxygen content) TVOC 1–5 (26) (27) Tetrachloromethane ≤ 0,5 g/t MDI produced (28) ≤ 0,7 g/t TDI produced (28) Cl2 < 1 (27) (29) HCl 2–10 (27) PCDD/F 0,025–0,08 ng I-TEQ/Nm3 (27) The associated monitoring is in BAT 2.

BAT 67: In order to reduce emissions to air of PCDD/F from a thermal oxidiser (see Section 12.1) treating process off-gas streams containing chlorine and/or chlorinated compounds, BAT is to use technique a, if necessary followed by technique b, given below. Technique Description Applicability a. Rapid quenching Rapid cooling of exhaust gases to prevent the de novo synthesis of PCDD/F Generally applicable b. Activated carbon injection Removal of PCDD/F by adsorption onto activated carbon that is injected into the exhaust gas, followed by dust abatement BAT-associated emission levels (BAT-AELs): See Table 9.1.

9.2. Emissions to water

BAT 68: BAT is to monitor emissions to water with at least the frequency given below and in accordance with EN standards. If EN standards are not available, BAT is to use ISO, national or other international standards that ensure the provision of data of an equivalent scientific quality. Substance/Parameter Plant Sampling point Standard(s) Minimum monitoring frequency Monitoring associated with TOC DNT plant Outlet of the pretreatment unit EN 1484 Once every week (30) BAT 70 MDI and/or TDI plant Outlet of the plant Once every month BAT 72 Aniline MDA plant Outlet of the final waste water treatment No EN standard available Once every month BAT 14 Chlorinated solvents MDI and/or TDI plant Various EN standards available (e.g. EN ISO 15680) BAT 14

BAT 69: In order to reduce the load of nitrite, nitrate and organic compounds discharged from the DNT plant to waste water treatment, BAT is to recover raw materials, to reduce the waste water volume and to reuse water by using an appropriate combination of the techniques given below. Technique Description Applicability a. Use of highly concentrated nitric acid Use highly concentrated HNO3 (e.g. about 99 %) to increase the process efficiency and to reduce the waste water volume and the load of pollutants Applicability to existing units may be restricted by design and/or operational constraints b. Optimised regeneration and recovery of spent acid Perform the regeneration of the spent acid from the nitration reaction in such a way that water and the organic content are also recovered for reuse, by using an appropriate combination of evaporation/distillation, stripping and condensation Applicability to existing units may be restricted by design and/or operational constraints c. Reuse of process water to wash DNT Reuse process water from the spent acid recovery unit and the nitration unit to wash DNT Applicability to existing units may be restricted by design and/or operational constraints d. Reuse of water from the first washing step in the process Nitric and sulphuric acid are extracted from the organic phase using water. The acidified water is returned to the process, for direct reuse or further processing to recover materials Generally applicable e. Multiple use and recirculation of water Reuse water from washing, rinsing and equipment cleaning e.g. in the counter-current multistep washing of the organic phase Generally applicable BAT-associated waste water volume: See Table 9.2.

BAT 70: In order to reduce the load of poorly biodegradable organic compounds discharged from the DNT plant to further waste water treatment, BAT is to pretreat the waste water using one or both of the techniques given below. Technique Description Applicability a. Extraction See Section 12.2 Generally applicable b. Chemical oxidation See Section 12.2

Table 9.2 BAT-AEPLs for discharge from the DNT plant at the outlet of the pretreatment unit to further waste water treatment Parameter BAT-AEPL (average of values obtained during 1 month) TOC < 1 kg/t DNT produced Specific waste water volume < 1 m3/t DNT produced The associated monitoring for TOC is in BAT 68.

BAT 71: In order to reduce waste water generation and the organic load discharged from the TDA plant to waste water treatment, BAT is to use a combination of techniques a., b. and c. and then to use technique d. as given below. Technique Description Applicability a. Evaporation See Section 12.2 Generally applicable b. Stripping See Section 12.2 c. Extraction See Section 12.2 d. Reuse of water Reuse of water (e.g. from condensates or from scrubbing) in the process or in other processes (e.g. in a DNT plant). The extent to which water can be reused at existing plants may be restricted by technical constraints Generally applicable

Table 9.3 BAT-AEPL for discharge from the TDA plant to waste water treatment Parameter BAT-AEPL (average of values obtained during 1 month) Specific waste water volume < 1 m3/t TDA produced

BAT 72: In order to prevent or reduce the organic load discharged from MDI and/or TDI plants to final waste water treatment, BAT is to recover solvents and reuse water by optimising the design and operation of the plant. Table 9.4 BAT-AEPL for discharge to waste water treatment from a TDI or MDI plant Parameter BAT-AEPL (average of values obtained during 1 year) TOC < 0,5 kg/t product (TDI or MDI) (31) The associated monitoring is in BAT 68.

BAT 73: In order to reduce the organic load discharged from a MDA plant to further waste water treatment, BAT is to recover organic material using one or a combination of the techniques given below. Technique Description Applicability a. Evaporation See Section 12.2. Used to facilitate extraction (see technique b) Generally applicable b. Extraction See Section 12.2. Used to recover/remove MDA Generally applicable c. Steam stripping See Section 12.2. Used to recover/remove aniline and methanol For methanol, the applicability depends on the assessment of alternative options as part of the waste water management and treatment strategy d. Distillation See Section 12.2. Used to recover/remove aniline and methanol

9.3. Residues

BAT 74: In order to reduce the amount of organic residues being sent for disposal from the TDI plant, BAT is to use a combination of the techniques given below. Technique Description Applicability Techniques to prevent or reduce the generation of waste a. Minimisation of high-boiling residue formation in distillation systems See BAT 17b. Only applicable to new distillation units or major plant upgrades Techniques to recover organic material for reuse or recycling b. Increased recovery of TDI by evaporation or further distillation Residues from distillation are additionally processed to recover the maximum amount of TDI contained therein, e.g. using a thin film evaporator or other short-path distillation units followed by a dryer. Only applicable to new distillation units or major plant upgrades c. Recovery of TDA by chemical reaction Tars are processed to recover TDA by chemical reaction (e.g. hydrolysis). Only applicable to new plants or major plant upgrades

10. BAT CONCLUSIONS FOR ETHYLENE DICHLORIDE AND VINYL CHLORIDE MONOMER PRODUCTION

The BAT conclusions in this section apply in addition to the general BAT conclusions given in Section 1.

10.1. Emissions to air

10.1.1. BAT-AEL for emissions to air from an EDC cracker furnace

Table 10.1

BAT-AELs for emissions to air of NOX from an EDC cracker furnace

Parameter BAT-AELs (32) (33) (34) (daily average or average over the sampling period) (mg/Nm3, at 3 vol-% O2) NOx 50–100

The associated monitoring is in BAT 1.

10.1.2. Techniques and BAT-AEL for emissions to air from other sources

BAT 75: In order to reduce the organic load sent to the final waste gas treatment and to reduce raw material consumption, BAT is to use all of the techniques given below. Technique Description Applicability Process-integrated techniques a. Control of feed quality Control the quality of the feed to minimise the formation of residues (e.g. propane and acetylene content of ethylene; bromine content of chlorine; acetylene content of hydrogen chloride) Generally applicable b. Use of oxygen instead of air for oxychlorination Only applicable to new oxychlorination plants or major oxychlorination plant upgrades Techniques to recover organic material c. Condensation using chilled water or refrigerants Use condensation (see Section 12.1) with chilled water or refrigerants such as ammonia or propylene to recover organic compounds from individual vent gas streams before sending them to final treatment Generally applicable

BAT 76: In order to reduce emissions to air of organic compounds (including halogenated compounds), HCl and Cl2, BAT is to treat the combined waste gas streams from EDC and/or VCM production by using a thermal oxidiser followed by two-stage wet scrubbing. Description: For the description of thermal oxidiser, wet and caustic scrubbing, see Section 12.1. Thermal oxidation can be carried out in a liquid waste incineration plant. In this case, the oxidation temperature exceeds 1 100 °C with a minimum residence time of 2 seconds, with subsequent rapid cooling of exhaust gases to prevent the de novo synthesis of PCDD/F. Scrubbing is carried out in two stages: Wet scrubbing with water and, typically, recovery of hydrochloric acid, followed by wet scrubbing with caustic. Table 10.2 BAT-AELs for emissions of TVOC, the sum of EDC and VCM, Cl2, HCl and PCDD/F to air from the production of EDC/VCM Parameter BAT-AEL (daily average or average over the sampling period) (mg/Nm3, at 11 vol-% O2) TVOC 0,5–5 Sum of EDC and VCM < 1 Cl2 < 1–4 HCl 2–10 PCDD/F 0,025–0,08 ng I-TEQ/Nm3 The associated monitoring is in BAT 2.

BAT 77: In order to reduce emissions to air of PCDD/F from a thermal oxidiser (see Section 12.1) treating process off-gas streams containing chlorine and/or chlorinated compounds, BAT is to use technique a, if necessary followed by technique b, given below. Technique Description Applicability a. Rapid quenching Rapid cooling of exhaust gases to prevent the de novo synthesis of PCDD/F Generally applicable b. Activated carbon injection Removal of PCDD/F by adsorption onto activated carbon that is injected into the exhaust gas, followed by dust abatement BAT-associated emission levels (BAT-AELs): See Table 10.2.

BAT 78: In order to reduce emissions to air of dust and CO from the decoking of the cracker tubes, BAT is to use one of the techniques to reduce the frequency of decoking given below and one or a combination of the abatement techniques given below. Technique Description Applicability Techniques to reduce the frequency of decoking a. Optimisation of thermal decoking Optimisation of operating conditions, i.e. airflow, temperature and steam content across the decoking cycle, to maximise coke removal Generally applicable b. Optimisation of mechanical decoking Optimise mechanical decoking (e.g. sand jetting) to maximise coke removal as dust Generally applicable Abatement techniques c. Wet dust scrubbing See Section 12.1 Only applicable to thermal decoking d. Cyclone See Section 12.1 Generally applicable e. Fabric filter See Section 12.1 Generally applicable

10.2. Emissions to water

BAT 79: BAT is to monitor emissions to water with at least the frequency given below and in accordance with EN standards. If EN standards are not available, BAT is to use ISO, national or other international standards that ensure the provision of data of an equivalent scientific quality. Substance/Parameter Plant Sampling point Standard(s) Minimum monitoring frequency Monitoring associated with EDC All plants Outlet of the waste water stripper EN ISO 10301 Once every day BAT 80 VCM Copper Oxy-chlorination plant using the fluidised-bed design Outlet of the pretreatment for solids removal Various EN standards available, e.g. EN ISO 11885, EN ISO 15586, EN ISO 17294-2 Once every day (35) BAT 81 PCDD/F No EN standard available Once every 3 months Total suspended solids (TSS) EN 872 Once every day (35) Copper Oxy-chlorination plant using the fluidised-bed design Outlet of the final waste water treatment Various EN standards available, e.g. EN ISO 11885, EN ISO 15586, EN ISO 17294-2 Once every month BAT 14 and BAT 81 EDC All plants EN ISO 10301 Once every month BAT 14 and BAT 80 PCDD/F No EN standard available Once every 3 months BAT 14 and BAT 81

BAT 80: In order to reduce the load of chlorinated compounds discharged to further waste water treatment and to reduce emissions to air from the waste water collection and treatment system, BAT is to use hydrolysis and stripping as close as possible to the source. Description: For the description of hydrolysis and stripping, see Section 12.2. Hydrolysis is carried out at alkaline pH to decompose chloral hydrate from the oxychlorination process. This results in the formation of chloroform which is then removed by stripping, together with EDC and VCM. BAT-associated environmental performance levels (BAT-AEPLs): See Table 10.3. BAT-associated emission levels (BAT-AELs) for direct emissions to a receiving water body at the outlet of the final treatment: See Table 10.5. Table 10.3 BAT-AEPLs for chlorinated hydrocarbons in waste water at the outlet of a waste water stripper Parameter BAT-AEPL (average of values obtained during 1 month) (36) EDC 0,1–0,4 mg/l VCM < 0,05 mg/l The associated monitoring is in BAT 79.

BAT 81: In order to reduce emissions to water of PCDD/F and copper from the oxychlorination process, BAT is to use technique a. or, alternatively, technique b together with an appropriate combination of techniques c., d. and e. given below. Technique Description Applicability Process-integrated techniques a. Fixed-bed design for oxychlorination Oxychlorination reaction design: in the fixed-bed reactor, catalyst particulates entrained in the overhead gaseous stream are reduced Not applicable to existing plants using the fluidised-bed design b. Cyclone or dry catalyst filtration system A cyclone or a dry catalyst filtration system reduces catalyst losses from the reactor and therefore also their transfer to waste water Only applicable to plants using the fluidised-bed design Waste water pretreatment c. Chemical precipitation See Section 12.2. Chemical precipitation is used to remove dissolved copper Only applicable to plants using the fluidised-bed design d. Coagulation and flocculation See Section 12.2 Only applicable to plants using the fluidised-bed design e. Membrane filtration (micro- or ultrafiltration) See Section 12.2 Only applicable to plants using the fluidised-bed design

Table 10.4 BAT-AEPLs for emissions to water from EDC production via oxychlorination at the outlet of the pretreatment for solids removal at plants using the fluidised-bed design Parameter BAT-AEPL (average of values obtained during 1 year) Copper 0,4–0,6 mg/l PCDD/F < 0,8 ng I-TEQ/l Total suspended solids (TSS) 10–30 mg/l The associated monitoring is in BAT 79. Table 10.5 BAT-AELs for direct emissions of copper, EDC and PCDD/F to a receiving water body from EDC production Parameter BAT-AEL (average of values obtained during 1 year) Copper 0,04–0,2 g/t EDC produced by oxychlorination (37) EDC 0,01–0,05 g/t EDC purified (38) (39) PCDD/F 0,1– 0,3 μg I-TEQ/t EDC produced by oxychlorination The associated monitoring is in BAT 79.

10.3. Energy efficiency

BAT 82: In order to use energy efficiently, BAT is to use a boiling reactor for the direct chlorination of ethylene. Description: The reaction in the boiling reactor system for the direct chlorination of ethylene is typically carried out at a temperature between below 85 °C and 200 °C. In contrast to the low-temperature process, it allows for the effective recovery and reuse of the heat of reaction (e.g. for the distillation of EDC). Applicability: Only applicable to new direct chlorination plants.

BAT 83: In order to reduce the energy consumption of EDC cracker furnaces, BAT is to use promoters for the chemical conversion. Description: Promoters, such as chlorine or other radical-generating species, are used to enhance the cracking reaction and reduce the reaction temperature and therefore the required heat input. Promoters may be generated by the process itself or added.

10.4. Residues

BAT 84: In order to reduce the amount of coke being sent for disposal from VCM plants, BAT is to use a combination of the techniques given below. Technique Description Applicability a. Use of promoters in cracking See BAT 83 Generally applicable b. Rapid quenching of the gaseous stream from EDC cracking The gaseous stream from EDC cracking is quenched by direct contact with cold EDC in a tower to reduce coke formation. In some cases, the stream is cooled by heat exchange with cold liquid EDC feed prior to quenching Generally applicable c. Pre-evaporation of EDC feed Coke formation is reduced by evaporating EDC upstream of the reactor to remove high-boiling coke precursors Only applicable to new plants or major plant upgrades d. Flat flame burners A type of burner in the furnace that reduces hot spots on the walls of the cracker tubes Only applicable to new furnaces or major plant upgrades

BAT 85: In order to reduce the amount of hazardous waste being sent for disposal and to increase resource efficiency, BAT is to use all of the techniques given below. Technique Description Applicability a. Hydrogenation of acetylene HCl is generated in the EDC cracking reaction and recovered by distillation. Hydrogenation of the acetylene present in this HCl stream is carried out to reduce the generation of unwanted compounds during oxychlorination. Acetylene values below 50 ppmv at the outlet of the hydrogenation unit are advisable Only applicable to new plants or major plant upgrades b. Recovery and reuse of HCl from incineration of liquid waste HCl is recovered from incinerator off-gas by wet scrubbing with water or diluted HCl (see Section 12.1) and reused (e.g. in the oxychlorination plant) Generally applicable c. Isolation of chlorinated compounds for use Isolation and, if needed, purification of by-products for use (e.g. monochloroethane and/or 1,1,2-trichloroethane, the latter for the production of 1,1-dichloroethylene) Only applicable to new distillation units or major plant upgrades. Applicability may be restricted by a lack of available uses for these compounds

11. BAT CONCLUSIONS FOR HYDROGEN PEROXIDE PRODUCTION

The BAT conclusions in this section apply in addition to the general BAT conclusions given in Section 1.

11.1. Emissions to air

BAT 86: In order to recover solvents and to reduce emissions of organic compounds to air from all units other than the hydrogenation unit, BAT is to use an appropriate combination of the techniques given below. In the case of using air in the oxidation unit, this includes at least technique d. In the case of using pure oxygen in the oxidation unit, this includes at least technique b. using chilled water. Technique Description Applicability Process-integrated techniques a. Optimisation of the oxidation process Process optimisation includes elevated oxidation pressure and reduced oxidation temperature in order to reduce the solvent vapour concentration in the process off-gas Only applicable to new oxidation units or major plant upgrades b. Techniques to reduce solids and/or liquids entrainment See Section 12.1 Generally applicable Techniques to recover solvent for reuse c. Condensation See Section 12.1 Generally applicable d. Adsorption (regenerative) See Section 12.1 Not applicable to process off-gas from oxidation with pure oxygen

Table 11.1 BAT-AELs for emissions of TVOC to air from the oxidation unit Parameter BAT-AEL (40) (daily average or average over the sampling period) (41) (no correction for oxygen content) TVOC 5–25 mg/Nm3 (42) The associated monitoring is in BAT 2.

BAT 87: In order to reduce emissions of organic compounds to air from the hydrogenation unit during start-up operations, BAT is to use condensation and/or adsorption. Description: For the description of condensation and adsorption, see Section 12.1.

BAT 88: In order to prevent benzene emissions to air and water, BAT is not to use benzene in the working solution.

11.2. Emissions to water

BAT 89: In order to reduce the waste water volume and the organic load discharged to waste water treatment, BAT is to use both of the techniques given below. Technique Description Applicability a. Optimised liquid phase separation Separation of organic and aqueous phases with appropriate design and operation (e.g. sufficient residence time, phase boundary detection and control) to prevent any entrainment of undissolved organic material Generally applicable b. Reuse of water Reuse of water, e.g. from cleaning or liquid phase separation. The extent to which water can be reused in the process depends on product quality considerations Generally applicable

BAT 90: In order to prevent or reduce emissions to water of poorly bioeliminable organic compounds, BAT is to use one of the techniques given below. Technique Description a. Adsorption See Section 12.2. Adsorption is carried out prior to sending waste water streams to the final biological treatment b. Waste water incineration See Section 12.2 Applicability: Only applicable to waste water streams carrying the main organic load from the hydrogen peroxide plant and when the reduction of the TOC load from the hydrogen peroxide plant by means of biological treatment is lower than 90 %.

12. DESCRIPTIONS OF TECHNIQUES

12.1. Process off-gas and waste gas treatment techniques

Technique Description Adsorption A technique for removing compounds from a process off-gas or waste gas stream by retention on a solid surface (typically activated carbon). Adsorption may be regenerative or non-regenerative (see below). Adsorption (non-regenerative) In non-regenerative adsorption, the spent adsorbent is not regenerated but disposed of. Adsorption (regenerative) Adsorption where the adsorbate is subsequently desorbed, e.g. with steam (often on site) for reuse or disposal and the adsorbent is reused. For continuous operation, typically more than two adsorbers are operated in parallel, one of them in desorption mode. Catalytic oxidiser Abatement equipment which oxidises combustible compounds in a process off-gas or waste gas stream with air or oxygen in a catalyst bed. The catalyst enables oxidation at lower temperatures and in smaller equipment compared to a thermal oxidiser. Catalytic reduction NOx is reduced in the presence of a catalyst and a reducing gas. In contrast to SCR, no ammonia and/or urea are added. Caustic scrubbing The removal of acidic pollutants from a gas stream by scrubbing using an alkaline solution. Ceramic/metal filter Ceramic filter material. In circumstances where acidic compounds such as HCl, NOX, SOX and dioxins are to be removed, the filter material is fitted with catalysts and the injection of reagents may be necessary. In metal filters, surface filtration is carried out by sintered porous metal filter elements. Condensation A technique for removing the vapours of organic and inorganic compounds from a process off-gas or waste gas stream by reducing its temperature below its dew point so that the vapours liquefy. Depending on the operating temperature range required, there are different methods of condensation, e.g. cooling water, chilled water (temperature typically around 5 °C) or refrigerants such as ammonia or propene. Cyclone (dry or wet) Equipment for removal of dust from a process off-gas or waste gas stream based on imparting centrifugal forces, usually within a conical chamber. Electrostatic precipitator (dry or wet) A particulate control device that uses electrical forces to move particles entrained within a process off-gas or waste gas stream onto collector plates. The entrained particles are given an electrical charge when they pass through a corona where gaseous ions flow. Electrodes in the centre of the flow lane are maintained at a high voltage and generate the electrical field that forces the particles to the collector walls. Fabric filter Porous woven or felted fabric through which gases flow to remove particles by use of a sieve or other mechanisms. Fabric filters can be in the form of sheets, cartridges or bags with a number of the individual fabric filter units housed together in a group. Membrane separation Waste gas is compressed and passed through a membrane which relies on the selective permeability of organic vapours. The enriched permeate can be recovered by methods such as condensation or adsorption, or can be abated, e.g. by catalytic oxidation. The process is most appropriate for higher vapour concentrations. Additional treatment is, in most cases, needed to achieve concentration levels low enough to discharge. Mist filter Commonly mesh pad filters (e.g. mist eliminators, demisters) which usually consist of woven or knitted metallic or synthetic monofilament material in either a random or specific configuration. A mist filter is operated as deep-bed filtration, which takes place over the entire depth of the filter. Solid dust particles remain in the filter until it is saturated and requires cleaning by flushing. When the mist filter is used to collect droplets and/or aerosols, they clean the filter as they drain out as a liquid. It works by mechanical impingement and is velocity-dependent. Baffle angle separators are also commonly used as mist filters. Regenerative thermal oxidiser (RTO) Specific type of thermal oxidiser (see below) where the incoming waste gas stream is heated by a ceramic-packed bed by passing through it before entering the combustion chamber. The purified hot gases exit this chamber by passing through one (or more) ceramic-packed bed(s) (cooled by an incoming waste gas stream in an earlier combustion cycle). This reheated packed bed then begins a new combustion cycle by preheating a new incoming waste gas stream. The typical combustion temperature is 800–1 000 °C. Scrubbing Scrubbing or absorption is the removal of pollutants from a gas stream by contact with a liquid solvent, often water (see ‘Wet scrubbing’). It may involve a chemical reaction (see ‘Caustic scrubbing’). In some cases, the compounds may be recovered from the solvent. Selective catalytic reduction (SCR) The reduction of NOX to nitrogen in a catalytic bed by reaction with ammonia (usually supplied as an aqueous solution) at an optimum operating temperature of around 300–450 °C. One or more layers of catalyst may be applied. Selective non-catalytic reduction (SNCR) The reduction of NOX to nitrogen by reaction with ammonia or urea at a high temperature. The operating temperature window must be maintained between 900 °C and 1 050 °C. Techniques to reduce solids and/or liquids entrainment Techniques that reduce the carry-over of droplets or particles in gaseous streams (e.g. from chemical processes, condensers, distillation columns) by mechanical devices such as settling chambers, mist filters, cyclones and knock-out drums. Thermal oxidiser Abatement equipment which oxidises the combustible compounds in a process off-gas or waste gas stream by heating it with air or oxygen to above its auto-ignition point in a combustion chamber and maintaining it at a high temperature long enough to complete its combustion to carbon dioxide and water. Thermal reduction NOX is reduced at elevated temperatures in the presence of a reducing gas in an additional combustion chamber, where an oxidation process takes place but under low oxygen conditions/deficit of oxygen. In contrast to SNCR, no ammonia and/or urea are added. Two-stage dust filter A device for filtering on a metal gauze. A filter cake builds up in the first filtration stage and the actual filtration takes place in the second stage. Depending on the pressure drop across the filter, the system switches between the two stages. A mechanism to remove the filtered dust is integrated into the system. Wet scrubbing See ‘Scrubbing’ above. Scrubbing where the solvent used is water or an aqueous solution, e.g. caustic scrubbing for abating HCl. See also ‘Wet dust scrubbing’. Wet dust scrubbing See ‘Wet scrubbing’ above. Wet dust scrubbing entails separating the dust by intensively mixing the incoming gas with water, mostly combined with the removal of the coarse particles by the use of centrifugal force. In order to achieve this, the gas is released inside tangentially. The removed solid dust is collected at the bottom of the dust scrubber.

12.2. Waste water treatment techniques

All of the techniques listed below can also be used to purify water streams in order to enable reuse/recycling of water. Most of them are also used to recover organic compounds from process water streams.

Technique Description Adsorption Separation method in which compounds (i.e. pollutants) in a fluid (i.e. waste water) are retained on a solid surface (typically activated carbon). Chemical oxidation Organic compounds are oxidised with ozone or hydrogen peroxide, optionally supported by catalysts or UV radiation, to convert them into less harmful and more easily biodegradable compounds Coagulation and flocculation Coagulation and flocculation are used to separate suspended solids from waste water and are often carried out in successive steps. Coagulation is carried out by adding coagulants with charges opposite to those of the suspended solids. Flocculation is carried out by adding polymers, so that collisions of microfloc particles cause them to bond to produce larger flocs. Distillation Distillation is a technique to separate compounds with different boiling points by partial evaporation and recondensation. Waste water distillation is the removal of low-boiling contaminants from waste water by transferring them into the vapour phase. Distillation is carried out in columns, equipped with plates or packing material, and a downstream condenser. Extraction Dissolved pollutants are transferred from the waste water phase to an organic solvent, e.g. in counter-current columns or mixer-settler systems. After phase separation, the solvent is purified, e.g. by distillation, and returned to the extraction. The extract containing the pollutants is disposed of or returned to the process. Losses of solvent to the waste water are controlled downstream by appropriate further treatment (e.g. stripping). Evaporation The use of distillation (see above) to concentrate aqueous solutions of high-boiling substances for further use, processing or disposal (e.g. waste water incineration) by transferring water to the vapour phase. Typically carried out in multistage units with increasing vacuum,