SZW Type Steam Boiler

SZW type steam boiler, fully known as double-drum longitudinal reciprocating grate water tube steam boiler, is a commonly used assembled / package industrial boiler, mainly suitable for burning biomass fuels (such as wood chips, straw, rice husk) and coal.

   I. Model Meaning   

S: Water tube boiler

Z: Double-drum longitudinal arrangement

W: Reciprocating grate (movable grate)

   II. Core Structure & Working Principle   

1. Core Structure

Drum: Two drums arranged longitudinally. The upper drum is used for steam-water separation, and the lower drum collects boiler water.

Combustion System: The front part is the furnace, surrounded by water wall tubes; the bottom is a reciprocating grate, which realizes intermittent movement and combustion of fuel through mechanical driving.

Convection Heating Surface: Dense convection tube bundles are arranged between the upper and lower drums at the rear of the furnace, where flue gas performs heat exchange via transverse scouring.

Rear Heating Surface: Usually equipped with an economizer to preheat boiler feed water and improve overall thermal efficiency.

2. Working Process

Combustion: Fuel (biomass / coal) is fed from the front of the furnace, moving backward gradually on the reciprocating grate for combustion.

Radiant Heat Exchange: High-temperature flame and flue gas in the furnace heat the surrounding water walls, and water absorbs heat to vaporize.

Convective Heat Exchange: High-temperature flue gas enters the convection tube bundle area for secondary heat exchange.

Rear Heat Exchange: After preheating feed water through the economizer, flue gas is discharged through a dust collector and chimney.

Water Circulation: Boiler water circulates naturally among downcomers, water walls and convection tube bundles to continuously generate steam.

   III. Main Technical Parameters   

Structure type

   IV. Main Performance Features   、

Strong Fuel Adaptability

The reciprocating grate is especially suitable for loose biomass materials with high moisture, low calorific value and many impurities.

Stable combustion, less coking, and adaptable to mixed combustion of various fuels.

High Combustion Efficiency

Staged air supply + special furnace arch design, combined with secondary air disturbance, ensure sufficient combustion of volatile matter and less black smoke.

Large furnace chamber with a cyclone burnout chamber for full combustion of combustible gases.

Stable Operation & Easy Maintenance

Double-drum structure features high rigidity, reliable water circulation and stable steam quality.

Compared with chain grates, reciprocating grates have simpler structure, fewer failures and easier maintenance.

Excellent Environmental Performance

Adopts low-nitrogen combustion technology, with NOₓ emission as low as 100mg/m³.

Built-in cyclone dust removal in the furnace to reduce outlet dust concentration.

   V. Typical Application Fields   

Light industry: Papermaking, textile, food processing, wood processing

Chemical industry: Rubber, plastic, building materials production

Heating industry: Residential central heating, industrial park heating

Agriculture / Forestry: Biomass power plants, grain drying, wood drying