Structure of the chemical industry

Transcription

1 CEE-Lectures on Industrial Chemistry Lecture 1. Crystallization as an example of an industrial process (ex. of Ind. Inorg. Chemistry) Fundamentals (solubility (thermodynamics), kinetics, principle) Process design (reactors, processes) Applications, example: KCl Chem. Process Technologies: From raw materials to final products (ex. of Ind. Organic Chemistry energy raw material product-network Fossile resources as raw materials of the chem. industry & energy sources: From the resources to the base materials (general aspects) Resources Base materials and selected intermediates Oil ETHENE and its family tree Oil/nat. gas, coal syngas METHANOL and selected intermediates Fine chemicals manufacture Structure of the chemical industry Source: Moulijn, J.A., Makkee, M., van Diepen, A.: Chemical Process Technology, Wiley

2 Classification of chemicals In chemical industry, one usually distincts between commodities (bulk chemicals), fine chemicals and specialties Bulk and fine chemicals are identified acc. to specifications (what they are); specialties are identified acc. to performance (what they can do) e.g. Methanol Ammonia Acetic acid Volume Commodities Fine chemicals Specialties Character Classification of chemicals on the basis of volume and character e.g. advanced intermediates Bulk drugs Bulk pesticides Bulk vitamins Flavour & fragrance chemicals e.g. adhesives Diagnostics Disinfectants Pharmaceuticals Dyestuffs Perfumes Photoogr. chemicals Specialty polymers Source: A. Cybulski et al.: Fine chemicals manufacture technology and engineering. Elsevier, 2001 Fine chemicals: General Fine chemicals (FC): products of high & well-defined purity, manufactured in relatively small amounts and sold at relatively high price - reasonable limits: t/a and 10 $/kg - fine chemicals: products of large variety number exceeds size of global fine chemicals market (1993): Mio. $; average annual growth between 1989 and 1995: ~4.5%* - 2 trends visible: (1) custom synthesis: dedicated prod. for a single client; world-wide a Mio. $/a business (2) specialization in production of chemicals grouped in chemical trees characterized by same chemical roots (compounds) or the same/similar method of manufacturing Food additives Dyes & Pigments Fragrances & Flavours Other Drug industry Agrochemicals Division of fine chemicals production by outlet *Source: Cybulski, A.et al.: Fine chemicals manufacture technology and engineering. Elsevier,

3 Characteristics of bulk vs. fine chemicals manufacture Bulk Fine Volume (kt/a) > 10 < 10 Price ($/kg) < 10 > 10 Added value Low High Lifecycle Long Relatively short Processing Continuous Batch-wise Plants Dedicated Multi-purpose & -product (MPP s) Flexibility Low High Raw materials quote Relatively high (raw material costs could represent >80% of total costs) Labour costs/kg product Low High Capital investment/kg product High Relatively low Producers Many Limited number Waste per kg product Relatively low High Even higher (fixed costs could be reduced by process simplification..e.g. less steps) Source: Cybulski, A.et al.: Fine chemicals manufacture technology and engineering. Elsevier, 2001 Multi-Purpose and Multi-Product-Plants (MPP s) Heart of the plant Typically consist of: Stirred stainless-steel & glass-lined batch reactors with reflux condensers Feed systems for gaseous, liquid and solid reactants Feed systems for blanketing with inert gases Equipment for separation and purification, e.g. Filters, centrifuges (most fine chemicals are solids!) fluidized-bed driers, tray driers, rotary driers Distillation equipment Facilities for recovery of solvents Storage facilities Effluent treatment facilities Sewage treatment Liquids and solids incinerators Off-gas treatment Utilities 3

4 Batch reactor systems (1) Heat exchange area limited (esp. with glass-lined reactors); internal coil hinders stirring, cleaning and inline sensors (1) (2) When large heat exchange area needed, external heat exchanger: part of liquid circulated; no agitator required, liquid circulation provides mixing (1). when reaction at boiling point, reflux condenser can be used (2). Typical practically used batch reactor systems Batch reactor systems (2) (special reactors) 1 reactant is gaseous (g-l reactions): Mechanically stirred tank reactor, where gas is supplied through a sparger plate semi-batch reactor (1 reactant (g) continuous, 1 reactant (l) loaded) Bubble-column reactors Spray columns g-l-s-systems: common when solid catalyst is present Fixed bed reactors Reactors with moving catalyst particles Suspension reactors (stirred tank, bubble-column, jet-loop (venturi) reactor) (for fine catalyst particles <200µm) (3-phase fluidized-bed reactor (for larger catalyst particles <3mm)) 4

5 Example: Aspirin production (Bayer trademark) Synthesis routes to acetylsalicylic acid Kolbe- Schmittreaction Salicin isolated from willow bark (historical/natural route) current industrial route via phenol (Kolbe-Schmittreaction: carboxylation) Salicylic acid Acetylsalicylic acid Main reaction: exothermic reaction of salicylic acid with acetic anhydride Acetylsalicylic acid: ester of salicylic acid (provides the hydroxyl group) and acetic acid Production of acetylsalicylic acid (ASA) - so called dedicated plant (no MPP) - production volume: ~ t/a (not clearly a fine chem. process) ASS crystals (storage) (reaction: esterification) (crystallization) (downstream processing) Glass-lined or stainless-steel batch reactor; solvent: HAc, (CCl 4, hydrocarbons) Reaction period: 2-3 h; T must be kept below 90 C ( R H < 0) After reaction, liquid product mixture is pumped to a crystallizer, where it is cooled to 0 C Suspension is transferred to a filter for mother liquor removal; crystals are washed with solvent, afterwards slurried and washed again; dried HAc as by-product is recovered; solvent and unconverted anhydride are recycled to the reactor 5