SZS Oil/Gas-Fired Saturated Steam Boiler

The two drums are arranged longitudinally in a D layout, with the furnace on the right and convective banks on the left. Movable supports at the lower drum center and ends allow expansion toward both ends. Rear convective tubes are more widely spaced and staggered, with in-line tubes at the front. Gas leaves the furnace rear, enters the burnout chamber and convective banks, then turns at the left front into the heat-recovery surfaces before chimney discharge.

A spiral-finned-tube economizer and condenser are provided at the tail end. Manholes are fitted at both ends of the upper and lower drums, with an inspection door at the rear.

Design and features

D-type membrane-wall construction

Membrane water walls surround the furnace; the left wall seals it from the convective banks. Walls and upper/lower drums are fully seal-welded to limit gas bypass and water leakage.

Insulation and gas tightness

High-density aluminum-silicate insulation and castable material reduce body weight, with radiant-heat insulation measures. The gas side operates sealed at slight positive pressure to reduce air leakage; no separate forced-draft fan is required.

Explosion-relief door and access

A spring-loaded top explosion-relief door provides pressure relief, while inspection doors and manholes provide maintenance access.

Heat-transfer optimization

Optimization considers air velocity, gas flow and impingement surfaces, gas/air pressure losses, and radiant/convective section geometry.

Calculation basis: lower heating values of 8400 kcal/Nm³ for natural gas and 10250 kcal/kg for diesel. Y denotes oil firing and Q denotes gas firing.