About BIS

The Bureau of Indian Standards (BIS) is India’s national standards body responsible for developing and maintaining technical standards to ensure quality, safety, and efficiency across industries. This draft standard specifies the material, construction, performance, and testing requirements for Biomass Hammer Mills, used for size reduction of agro-residues in pellet and briquette production.

Purpose of Draft

The draft aims to:

Provide uniform specifications for biomass hammer mills.
Assist manufacturers in selecting appropriate materials and ensuring safety compliance.
Standardize testing methods for evaluating hammer mill performance at no-load, load, and during long-run endurance.
Promote efficient biomass utilization in pellet plants for co-firing in thermal power plants, reducing reliance on coal and supporting environmental sustainability.

Key Points Summary

Defines types of hammer mills (reversible, non-reversible, light, medium, heavy duty).
Prescribes material standards for components (IS 2062, IS 1079, ASTM-A48, etc.).
Specifies constructional requirements (housing ≥12 mm thickness, hammer ≥5 mm thickness, rotor 1200–2800 rpm).
Includes safety features (emergency stops, temperature monitoring, limit switches).
Provides testing protocols at no-load, load, and long-run operation.
Ensures compliance with noise limits (≤86 dB) and durability standards.

Scope

This standard covers material, performance, construction, and testing requirements for biomass hammer mills used in pellet and briquette plants. It applies to hammer mills of all sizes, duty categories, and designs.

Terminology

Biomass Hammer Mill: Equipment used to crush raw biomass into fine particles (<3.15 mm).
Desired Particle: Particle size less than 3.15 mm.
Feed Mechanism: System for uniform biomass feeding and regulating feed rate.

Types of Hammer Mill

Based on Direction of Rotation:
- Reversible: Rotation can change direction, extending hammer life.
- Non-Reversible: Fixed direction, simple design, lower cost.
Based on Power Consumption:
- Light Duty: <200 kW, small-scale/feed operations.
- Medium Duty: 200–500 kW, industrial biomass processing.
- Heavy Duty: >500 kW, large-scale, high durability.

Material Requirements

Key materials as per BIS:

Mild Steel (IS 2062): Base frame, cyclone, body frame, airlock.
EN8/EN9/Alloy Steel/Hardox/Abrex: Hammers and mounting pins.
Hot Rolled Carbon Steel (IS 1079): Screens.
CI ASTM-A48: Pulleys.
EN8 Shafts with IS 2062 compliance.
V-Belts IS 2494.

Blower/Cyclone/Induced Draft Fan (ID Fan)

Blower type: centrifugal with 3–8 blades.
Air volume: 3,600–540,000 m³/h.
Cyclone size: customized as per capacity.
ID Fan material: mild steel, IS 2062.
Pressure rating: up to 1.47 kPa (150 mm WC).

Test at Load and No Load (with Example)

No-Load Test

Run at rated speed for 10 minutes.
Measure power consumption.
Record vibrations, noise, heating, and mechanical issues (Annex E).

Load Test

Feed chopped biomass (moisture checked as per IS 17655).
Run for 20 hours at rated capacity.
Collect samples for moisture, particle size, density, energy consumption.
Run trials at 80%, 90%, 110%, 120% of rated capacity.
Calculate:
- Capacity (kg/h)
- Efficiency (%)
- Specific Energy Consumption (Wh/kg)
- Biomass Loss (kg)

Example

If input = 100 kg, output (desired particle) = 90 kg:

Efficiency = (90/100) × 100 = 90%.
Energy use difference (load–no load) ÷ throughput = Specific Energy Consumption.

Data Sheet for Test at Load (Long Run Test)

Parameters recorded (Annex F & H):

Feed composition and moisture.
Shaft speed (rpm), energy readings.
Output weight, particle size, density.
Observations on vibrations, heating, belt slip.
Endurance: Must operate 20 hours, continuous 5-hour runs, without major breakdown.

Summary Report

Includes details (Annex J):

Manufacturer, model, year.
Test material & moisture content.
Feed control adjustments.
Power requirement at no-load and load.
Efficiency, capacity, biomass loss, calorific value.
Major breakdowns (if any).
Final remarks on performance.

Conclusion

The BIS draft standard for Biomass Hammer Mills establishes a comprehensive framework for material quality, construction, performance, and safety testing. It ensures reliability, efficiency, and sustainability in biomass pellet production—supporting India’s shift toward renewable energy through co-firing in thermal power plants.

PDF Download

Samarth Committee PDF Download and Comments Link

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Disclaimer

This draft is for comments and reference only and must not be reproduced or used as an official BIS standard until formally adopted.