Intermittent Operation

Unlike continuous blowdown, intermittent bottom blowdown removes settled sludge and concentrated solids through periodic manual or timed valve opening. Large instantaneous flow at boiler pressure and temperature requires surge capacity preventing drainage system damage. Blowdown drums provide volume buffering, flash steam separation, and cooling enabling safe batch discharge handling.

Vessel Design

Horizontal drum sized for maximum blowdown volume from single discharge event typically 100-500 gallons. Inlet section withstands full boiler pressure. Flash chamber allows pressure reduction vaporizing portion of water. Cooled liquid section brings temperature to safe disposal levels below 60°C. ERGIL sizes drums based on boiler capacity, blowdown frequency, and batch volume.

Flash Steam Handling

Pressure reduction from 150-2400 psig to atmospheric vaporizes 10-30% of blowdown water. Flash steam at low pressure vents to atmosphere or routes to low-pressure recovery. Remaining liquid cools through flashing and optional makeup water dilution achieving safe discharge temperature.

Design Conditions

Inlet section rated for maximum boiler pressure with appropriate safety margin. Outlet section atmospheric or low pressure. Temperature ratings accommodate boiler saturation temperature with outlet cooling to disposal limits. Materials handle thermal shock from intermittent discharge cycles.

Material Selection

Carbon steel construction suitable for boiler feedwater chemistry. Proper corrosion allowances for concentrated dissolved solids. Internal baffling prevents erosion from high-velocity discharge. Design per ASME Section VIII with materials meeting power boiler standards.

Applications

Industrial steam boilers requiring periodic bottom blowdown, power plant auxiliary boilers, package boiler systems, marine boiler installations, and heating boilers with manual blowdown procedures. Serves facilities with boiler capacities from 10,000-200,000 lb/hr steam generation.

Control Features

Level switches manage batch accumulation and drainage preventing overflow. Temperature monitoring verifies adequate cooling before disposal. Pressure relief protects against blocked outlets. Simple manually-initiated or timer-controlled blowdown sequences.

Cooling Methods

Flash cooling through pressure reduction provides primary temperature drop. Makeup water injection provides supplemental cooling where required. Adequate residence time enables heat dissipation. Drainage to sewer only after temperature verification.

Performance Benefits

Safe handling of large batch blowdown volumes protecting drainage systems. Flash steam venting prevents pressure buildup. Temperature reduction meets disposal requirements. Simple robust design for intermittent service. Minimal maintenance with proven construction.

Construction Standards

Design per ASME Section VIII with appropriate code stamps. Relief valve protection sized for blocked outlet scenarios. Materials suitable for concentrated boiler water. Complete documentation with surge calculations and cooling analysis.

ERGIL intermittent blowdown drums deliver safe batch discharge handling enabling proper boiler bottom blowdown in steam generation facilities.