Centrifugal Blowers and Paddle Dryers for Process Industries

Process industry is a broad term that covers the most demanding air and gas handling conditions in manufacturing. Chemical plants, fertilizer complexes, refineries, specialty chemical units, dye and pigment manufacturers, textile processing facilities, rubber and plastic compounders, glass plants, and general manufacturing operations — each runs processes that generate gas streams, require combustion air, move dry materials, or produce wet intermediates that need controlled drying.

The common thread across all of them: the blower or dryer must be specified to the actual process conditions, not to a catalog average. Gas temperature, composition, particulate loading, humidity, and pressure drop across the system all determine whether a unit runs reliably for five years or fails its first service interval.

AS Engineers has supplied centrifugal blowers and paddle dryers to process industry clients across India for 24 years — including Coromandel International, Meghmani Organics Ltd, UPL Ltd, and Ashima Ltd. Every unit is engineered to the specific airflow volume, static pressure, temperature, and material of construction requirement of the application it serves.

Design range for centrifugal blowers: 100 to 2,50,000 m³/hr airflow, 25 to 2,100 mmWC static pressure, operating temperatures up to 650°C.

Centrifugal Blowers for Process Industry Applications

Combustion Air Supply — Process Heaters, Furnaces, and Boilers

Fired process heaters, tube furnaces, and package boilers in chemical and refinery plants require a continuous, controlled supply of combustion air to maintain the flame at the designed heat release rate. The forced-draft blower sets the excess air level that determines combustion efficiency, flue gas composition, and furnace temperature profile. An oversized blower wastes energy through excess air. An undersized blower causes incomplete combustion and process upset.

High pressure radial blade blowers and high temperature plug blowers are the standard choices for combustion air duty, depending on the furnace pressure and temperature profile. Where the burner location and duct layout require the blower to be positioned close to the heat source, plug fan arrangement keeps motor and bearings in the ambient temperature zone while the impeller handles the hot air side.

Reactor Ventilation and Corrosive Gas Exhaust

Chemical reactors — batch or continuous — generate vapour, off-gas, and fume that must be managed at the process boundary. The gas stream may contain acid vapours, organic solvents, reactive gases, or particulate entrained from the reaction. The blower pulling these streams must handle the composition and temperature without corrosion failure or accumulation of reactive deposits on the impeller.

Industrial exhauster radial blowers handle corrosive and particulate-laden gas streams in reactor ventilation duty. MOC selection is based on the specific gas: SS 304 for mildly acidic organic vapours; SS 316 or SS 316L for chlorinated or sulphur-bearing streams; Duplex SS 2205 for aggressive mixed-acid environments. Shaft seals are specified to prevent fugitive emission from corrosive or solvent-bearing gas streams.

Fluidised Bed and Calcination Air Supply

Fluidised bed reactors, dryers, and calciners in fertilizer, mineral processing, and specialty chemical plants require a controlled upward air or gas flow through the bed at a velocity that maintains fluidisation without entraining the product. The blower must deliver stable airflow across the operating range of bed depth and material density. High pressure radial blade blowers are sized to the minimum fluidisation velocity, bed pressure drop, and distributor plate resistance at the design throughput.

Pneumatic Conveying of Process Materials

Chemical intermediates, fertilizer granules, pigments, polymer powders, and fine process materials move between process steps through dilute phase pneumatic conveying systems. The blower provides the driving pressure across the conveying line. Selection depends on conveying distance, material bulk density, pipe diameter, and the product’s abrasivity and moisture sensitivity. Backward inclined blowers handle dry, non-abrasive process powders; radial blade geometry is used where the material or its fines have abrasive characteristics.

ETP Aeration for Process Plant Effluent

Chemical and fertilizer plant ETPs handle high-COD, sometimes high-TDS effluent streams from process washings, reactor drains, and condensate. Biological treatment zones require sustained dissolved oxygen levels, which depends on the aeration blower delivering consistent airflow to the diffuser grid against the static head of the tank depth. Backward curved centrifugal blowers are the standard choice for clean aeration air — stable operating point, non-overloading power curve, and high efficiency at the design duty.

Cooling Tower Fan Duty and Air-Side Heat Rejection

Process plants use forced-draft and induced-draft cooling towers to reject process heat. The cooling tower fan moves large air volumes at low static pressure across the fill media. Fan duty must be maintained at design performance across the ambient temperature range and the seasonal variation in cooling duty. Impeller selection and blade pitch are set to the tower design conditions. MOC is typically MS or aluminium depending on the water chemistry and atmospheric conditions at the plant site.

General Process Area Ventilation

Production buildings, compressor houses, pump rooms, battery rooms, and control buildings in process plants require positive or negative pressure ventilation to manage heat, fume, and classified area requirements. Ventilation rates are specified to the heat load, the gas generation rate for classified areas, and the number of air changes per hour mandated by the hazardous area classification. Industrial exhauster air handling blowers and backward curved units cover the volume-flow range of most process area ventilation duties.

Paddle Dryers for Process Industry Applications

AS Engineers’ paddle dryer for process industry applications uses indirect heat transfer. Heat passes from steam or thermic fluid circulating inside hollow, wedge-shaped paddles into the process material. There is no hot air contact. The dual counter-rotating shafts agitate the material continuously at low shaft speed, producing even heat distribution without localised overheating — important for thermally sensitive chemicals, crystalline intermediates, and heat-labile compounds.

Heating media options are steam, thermic fluid (up to 400°C), or hot water, chosen based on the process temperature requirement and available utility supply at the plant. For solvent-bearing or oxygen-sensitive materials, the dryer operates under nitrogen atmosphere or vacuum to prevent oxidation, solvent ignition risk, and loss of volatile components.

Process industry drying applications include:

• Chemical intermediates and wet cake: Filter cake from chemical synthesis, crystallisation, or precipitation typically contains 20–60% moisture. The paddle dryer reduces this to below 1–5% depending on the product specification, handling sticky, pasty, and abrasive materials without shaft fouling or bearing overload.
• Fertilizer and agrochemical products: Technical-grade fertilizers, wettable powders, and granulated agrochemical products require moisture control before packaging. The paddle dryer handles granular, powdery, and semi-crystalline fertilizer materials without particle attrition.
• Pigments, dyes, and specialty chemicals: Many pigment and dye intermediates are heat-sensitive and require temperature control during drying to avoid colour shift or decomposition. Operating at reduced paddle surface temperature with thermic fluid or hot water heating provides the precision these products require.
• Salt, sulphate, and crystalline products: The low-shear agitation of the paddle dryer preserves crystal structure and particle size distribution — products like sodium sulphate, ammonium sulphate, and crystalline specialty chemicals are dried without excessive fines generation.
• Process plant ETP sludge: Chemical and fertilizer plant ETP sludge classified under HW Rules 2016 is dried for volume reduction and co-processing. Operating cost: approximately Rs 5.45–7.50 per kg of dried output. Disposal cost avoided: approximately Rs 25 per kg. Volume reduction: 80–90%.

Process Industry Blower Selection Matrix

Non-Standard and Make-to-Order Process Applications

Process industry often produces requirements that fall outside standard product ranges — mixed corrosive gas streams at elevated temperatures, pulsating flow from batch reactors, unusually high static pressure at moderate airflow, or gas compositions that attack standard impeller alloys.

AS Engineers’ make-to-order capability is designed for exactly these situations. We engineer from the gas analysis and process conditions, not from a product catalog. SA516 Gr.70, SS 321, Duplex SS 2205, and hard-faced impellers are available for conditions that exceed standard material options. If your process condition does not fit a standard specification, share the gas composition, temperature, and pressure data with our engineering team and we will propose a design.

Why Process Industry Plants Qualify AS Engineers

• Confirmed supply to Coromandel International, Meghmani Organics Ltd, UPL Ltd, and Ashima Ltd across chemical, fertilizer, and process sectors
• Design to gas analysis and process conditions — not catalog selection
• Full MOC range: MS, CS, SS 304/304L/316/316L/321, Duplex SS 2205, SS 410, SA516 Gr.70, Aluminium, EN-8/9/24, Hard Facing
• Operating temperature capability up to 650°C, static pressure up to 2,100 mmWC
• ISO 9001:2015 certified manufacturing with performance test certificates, balancing reports, and material test certificates
• Dynamic balancing to G6.3 / G2.5 per IS 4894 — relevant for high-speed process fan applications where vibration affects downstream instrument reliability

Frequently Asked Questions

What is the maximum operating temperature for AS Engineers’ centrifugal blowers in process applications?

Our centrifugal blowers are designed for operating temperatures up to 650°C for process gas handling applications. At elevated temperatures, impeller material changes from standard MS to alloy steel, SS 321, or other temperature-rated grades depending on the gas composition and temperature profile. High temperature plug blower arrangements keep bearings and motor in the ambient temperature zone while the impeller handles the hot gas stream. Provide your gas temperature, composition, and pressure requirement for a specific material and design recommendation.

Which blower types are suitable for handling corrosive process gases in chemical plants?

Industrial exhauster radial blowers are the standard choice for corrosive gas exhaust in chemical plant applications. The radial blade geometry handles particulate carry-over and resists impeller fouling in gas streams with condensable vapours or sticky particulate. MOC selection — SS 304, SS 316L, or Duplex SS 2205 — is based on the specific corrosive species, concentration, and whether the gas is above or below the dew point at the blower inlet. Share your gas analysis and we will confirm the correct alloy and seal configuration.

Can AS Engineers supply blowers for pneumatic conveying of abrasive chemical products?

Yes. For abrasive process materials — silica, alumina, calcium carbonate, abrasive fertilizer granules — we supply radial blade centrifugal blowers with hard-facing on the impeller leading edge and wear plates in the casing inlet zone. The hard-facing material and thickness are selected based on the material’s Moh’s hardness and the conveying velocity at the blower inlet. Provide your material specification and conveying line data for a detailed recommendation.

What heating media options are available for paddle dryers in process industry?

Paddle dryers for process industry applications can use steam, thermic fluid (operating temperature up to 400°C), or hot water as the heating medium inside the hollow paddles. The choice depends on the process temperature requirement, the thermal sensitivity of the material being dried, and the available utility supply at your plant. For solvent-bearing or oxygen-sensitive materials, the dryer can be configured to operate under nitrogen atmosphere or vacuum to manage explosion risk and prevent oxidation of the product.

What is AS Engineers’ lead time for a custom-engineered process blower?

Lead time for process blowers depends on specification complexity, MOC selection, impeller diameter, and drive configuration. Standard MS or SS 304 blowers in the 500–5,000 CMH range typically deliver in 4–6 weeks. Large-diameter units, high-temperature alloy construction, or unusual drive arrangements require 8–12 weeks. Make-to-order blowers with non-standard pressure or temperature requirements are assessed individually — share your specification and we will provide a confirmed schedule with our technical response.

Process gas conditions rarely fit a standard product description. Share your application data — gas composition, temperature, flow rate, static pressure, and any MOC preferences — and our engineering team will respond with a specification, not a brochure.

Phone: +91 99090 33851 | +91 82386 77554 Email: info@theasengineers.com