THERMORIGENERATIVE COMBUSTOR FOR CHLORINATED OFF-GAS A SPECIFIC DESIGN FOR THE CHEMICAL-PHARMACEUTICAL INDUSTRY C+A

WHY AN AD HOC COMBUSTOR FOR CHLORINATED OFF-GAS? 1. The resort to organo-chlorinated solvents in the synthesis of pharmaceutical intermediate products, sometimes only during well defined campaigns, comes from the high characteristics of these compounds, which are often unreplaceable. 2. Under combustion chlorinated compounds produce HCl (hydrochloric acid). In some cases HCl is present in the off-gas input as well.

WHY AN AD HOC COMBUSTOR FOR CHLORINATED OFF-GAS? 3. The thermorigenerative combustor type is the highest efficiency combustor: it has the lowest support fuel consumption and exit temperatures of 60 ÷ 150°C. It is of simple construction but materials generally adopted result to be unfit for chlorinated off-gas. 4. In the combustor flue gases HCl has a dew point of ab. 200°C. Below this temperature HCl condensation (very corrosive) finds place. For T < 100°C condensation of water vapour produced by combustion brings in dilution of HCl condense, so decreasing the overall corrosiveness, which nonetheless remains high.

REFERENCE DESIGN PARAMETERS Data apply to off-gas thermorigenerative combustors in the Lombardia Region - Italy (D.g.r n. 7/12943 – Utilzation of best available technologies PC.T.02). The following main parameters apply: Organic chlorine in the VOC [% p.] Combustion chamber temperature [°C] Combustion chamber residence time [sec] Absent≥ 750≥ 0,6 ≤ 0,5≥ 850≥ 1,0 > 0,5 e ≤ 2,0 ≥ 950≥ 2,0 > 2,0≥ 1100≥ 2,0

POSSIBLE TECHNICAL SOLUTIONS After a careful study and examination of what has been been done in this field in Italy and Europe up till now, the technical solutions appear to be: After a careful study and examination of what has been been done in this field in Italy and Europe up till now, the technical solutions appear to be: SOLUTION A (high energy consumption) Enhancing the chlorinated off-gas inlet temperature to T ≥ 200°C by a heat exchanger - 270°C overheated steam / off-gas or double heat exchanger - 200°C steam/ off-gas and NG flue gases / off-gas), with relating high costs of heat exchangers (graphite) and of utilities.

POSSIBLE TECHNICAL SOLUTIONS SOLUTION B (with minimized energy consumption) Feeding the off-gas (chlorinated and non) directly to combustor, with no preheat, under the same conditions of off-gas release from production, or after scrubbers that may be introduced to reduce high concentration peaks of chlorinated compounds (alkaline scrubbing). Feeding auxiliary fuel (natural gas) for combustion chamber temperature control, leaving the combustor flue gas temperature uncontrolled: this shall then depend upon off-gas input flow (turn-down) and organic concentration / enthalpy of combustion.

BASE POINTS OF C+A PROJECT SOLUTION A Plant capacity Nm3/h SOLUTION B (C+A) Plant capacity Nm3/h Steam consumption (15 bar g - 200°C) for off-gas preheat 686 Kg/h0 Kg/h Natural gas consumption (34,953 KJ/Nm3) for off- gas preheat 32 Nm3/h0 Nm3/h Yearly cost (5,000 hrs/year) of steam and natural gas for off-gas preheat 131,000 Euro/year0 Euro/year COMPARISON OF UTILITIES CONSUMPTION AND RELATING COSTS FOR SOLUTIONS A AND B – 10,000 NM3/H OFF-GAS PLANT

BASE POINTS OF C+A PROJECT Steam ejector Concentr. off-gasDiluted off-gas 3 tower combustorHot gas by-pass Flue gas duct Scrubber-quencher Final chimneyFlue gas fan Natural gas NaOH 30%Salty drain OVERALL OFF-GAS INPUT FLOW: 5,000 ÷ 70,000 NM3/H

BASE POINTS OF C+A PROJECT Plant guaranteed emission concentrations: COMBUSTOR [mg/Nm3] SCRUBBER [mg/Nm3] TOC CO NOx HCl < 20 < 100 < 10 Values refer to measured oxygen level (= O2 as such)