HYGRADE INDUSTRIAL PLASTICS LIMITED AIR POLLUTION CONTROL

HYGRADE INDUSTRIAL PLASTICS LIMITED AIR POLLUTION CONTROL

CLEAN AIR With over 30 years experience in the design and manufacture of fume scrubbing and odour control systems, Hygrade Industrial Plastics occupies a premier position in this field. Hygrade with their extensive manufacturing facilities combine thermoplastics and an in-house process and mechanical design capability to produce corrosion resistant plant, which gives them a unique and enviable reputation for quality products throughout the chemical industry. Schematic of packed tower scrubber showing major components 2 Thermoforming materials used at Hygrade include: PVC Polypropylene Polyethylene PVDF ECTFE (Halar) PFA FEP When glass fibre reinforcement is applied the resins used fall into the following categories: Orthophthalic Isophthalic Bisphenol Vinyl esters Furane Hetron Front inset picture: Three stage NO x scrubber for a European electronics company. Venturi/packed tower supplied to a European chemical manufacturer to remove Acrylate fumes from a reaction vessel.

packed tower scrubbers Gas absorption within packed towers takes place in one of two ways, either: By physical contact and dissolution of gas in water or by A scrubbing reaction between the gas and a scrubbing reagent. The performance and efficiency of a packed tower scrubber is generally dependent upon the following factors: The packing surface area over which gas/liquid transfer will occur The even distribution of the scrubbing liquor throughout the packing Gas velocity through the packed bed The liquor flow rate through the packed bed A packed tower consists of the following main sections: Base Section or Sump Acts as a liquid reservoir for the column and is connected to the recirculation pump inlet. It also has connections for the adding of water, dosing of chemicals and drainage of spent liquor. Packed Bed Section, throughout which gas absorption occurs. The bed comprises many pieces of loose random packing, the size and shape of which is selected to give optimum scrubber performance. The bed is supported on a purpose built packing support plate. Upper Section Made up of the liquid distributor to ensure even liquor distribution across the packing. The distributor will be either a spray system, pan and riser or a trough type depending on the application. Above the distributor, a droplet eliminator prevents liquid carry over. The eliminator could be of a vertical or horizontal design depending on the outlet or discharge requirement. Typical examples of gases removed by these types of scrubber include: Phosphorus Trichloride and Hydrochloric Acid packed tower scrubber manufactured in Celmar and GRP. Hydrogen Chloride Ammonia Oxides of Nitrogen Sulphur Dioxide Phosgene Chlorine Hydrogen Sulphide Amines Bromine Nitric Acid Methanol Formaldehyde 1 Base tank/fume inlet 5 Recirculation tank 2 Scrubber body 6 Scrubbing liquid inlet 3 Top/spray section 7 Water make-up 4 Eliminator 8 Drain 3

venturi & impingement plate scrubbers Both the Venturi and Impingement Plate scrubbers rely on the creation of turbulence and high impact forces to ensure intimate contact between gas and scrubbing liquid. Left and below: All GRP Derakane venturi scrubber with adjustable throat for the removal of Hydrochloric Acid mist. The Venturi scrubber achieves this by accelerating the gas through a restricted area or throat. Liquid is introduced at the throat creating the high turbulence zone. Venturi scrubbers are available with both fixed and variable throats with the efficiency being a direct function of both the throat area and the liquid rate. Venturi scrubbers can be used either as a single stage unit for removal of fine particulates or aerosols, or as part of a multistage scrubber where they may be followed by a packed tower (for gaseous contaminants) or by successive venturi units when very high removal efficiencies are required. Impingement Plate scrubbers are counter-flow devices in which liquid is introduced at the top of the tower and flows down across a series of plates. These plates or baffles are perforated by holes or openings through which the contaminated air introduced at the bottom of the column flows. Gas/liquid contact occurs in pools of liquid as the liquid attempts to pass down the same holes through which the air is rising. Zones of turbulence are formed with the scrubbing efficiency being determined by the size and shape of the openings. Sprays are also directed on the underside of the plates to provide an initial opportunity for collision to occur between gas and liquid. This also eliminates any wet/dry interfaces which may cause plugging. Multi-stage venturi and packed tower scrubber for multi purpose duties including the removal of Methyl Mercaptan and acid gases. LIQUOR FEED Particulate matter which may be present in a gas stream can cause blockages if passed through a packed tower scrubber. Impingement Plate scrubbers are most widely used to overcome this problem. GAS INLET 4 Cut away of a venturi scrubber. GAS OUTLET

droplet eliminators & washbox scrubbers When liquid in the form of mist spray or droplets is entrained in an air or gas flow there is usually a need for its separation before the gas is discharged into the atmosphere. Typical examples of this are: Air treated by a wet chemical scrubber Spray towers Chillers Humidifiers Air conditioning units Hygrade droplet eliminators are designed to perform this function and are available in a wide range of chemically resistant plastics. Using profiled blades mounted in a horizontal eliminator, the gas and liquid droplets are subjected to inertia forces which cause separation from the liquid droplets impinging on the collection surfaces and falling to drain by gravity. Droplet Eliminators can be supplied as: Individual blades cut to any length Pre-assembled into cassette format Installed complete in a flanged mounted housing If the droplet eliminator is required to be installed in a vertical gas flow, Hygrade can also supply suitable units with either a profiled blade or mesh pad demister. Washbox scrubber installation for the removal of Sulpuric Acid droplets. The horizontal eliminator is usually supplied with a double bank of eliminator blades. By extending the housing, either an agglomerator pad, spray section or packed bed section can be added to form a Washbox scrubber. These units are designed for relatively low inlet concentrations but they offer a cost effective and low pressure drop solution to many contaminated air applications. Profiled droplet eliminator for vertical airflow. Air flow and moisture removal through eliminator blades. Horizontal bladed eliminator in cassette format complete with flanged casing. 5

other products & services Apart from a complete range of gas scrubbing plant, Hygrade also has unrivalled expertise and experience in the design and manufacture of the following corrosion resistant plant: Chemical storage tanks with or without glass fibre reinforcement Pressure vessels to BS4994 (1987) Cat. 1 scrubber internals Extraction ductwork and discharge stacks One off, tailor made specialist fabrications Pressure pipework systems To complement the above, Hygrade has its own unique metal fabrication facilities to provide structural supports, access ladders and other required steelwork items. Hygrade also has an in-house facility for the testing of laminate samples to BS4994. The tests check weld efficiency, peel and shear strength and are approved by ICI and many other inspection authorities. Right: ECTFE/GRP chemical storage tank for a major pharmaceutical company. Far right: All Derakane/GRP tilting reactor vessel, designed and manufactured by Hygrade. Below: PVC/GRP coater for the auto catalyst industry. 6

turnkey capability The system design experience within Hygrade enables the company to offer a complete Turnkey Package from conceptual design, through detailed process and mechanical design, in-house manufacture to on-site installation and commissioning. This provides a complete solution to a wide range of applications, with associated plant specified and incorporated into the scrubber package. Typical examples of the items used in conjunction with Hygrade scrubbers include: Pumps Pipework Fans Ductwork Instruments Dosing equipment Control panels Heat exchangers Steelwork Turnkey supply and installation package for a major pharmaceutical company in Southern Ireland. Major ducting and extraction system for a chemical manufacture in Northern Ireland. 7

complete system design Since its foundation many major UK companies have benefitted from Hygrade s expertise. Typical industries supplied by Hygrade include: Chemical and Fine Chemical Pharmaceutical Metallurgical Processing (Plating, Anodising, Etching, Pickling} Petrochemical Glass and Ceramics Sewage and Refuse We will be pleased to be of assistance should you require to discuss a particular application. TO C OVENTRY J UNCTION 1 M6 J UNCTION 19 M1 & A14 HYGRADE INDUSTRIAL PLASTICS LIMITED to Swift Valley A426 TO R UGBY to Coton Park Brownsover Estate B OUGHTON R OAD to Brownsover Hunters Lane off Newbold Road Rugby Elliot s Field Retail Park Old Viaduct to Newbold A4112 L EICESTER R OAD River TESCO H UNTERS L ANE Police Avon Rugby Station Mill Council Bridge Pub Depot N EWBOLD R OAD to Rugby Town Centre Avon HYGRADE INDUSTRIAL PLASTICS LIMITED Hygrade Industrial Plastics Limited Hunters Lane Rugby Warwickshire CV21 1EA United Kingdom Telephone: +44 (0) 1788 571316/542809 Facsimile: +44 (0) 1788 541184 E-mail: techsales@hygradeplastics.com Internet: http://www.hygradeplastics.com