From feed to concentrate
In a tubular falling-film evaporator, feed enters a distributor above vertical heating tubes. Liquid travels downward along the tube walls; vapor and remaining liquid reach a separator. Heating and product streams remain on opposite sides of the heat-transfer surface. Vacuum operation can lower the boiling temperature. Technical basis: GEA working principle.
Treat the package as a system
A buyer’s scope should identify the feed preparation, evaporator, separator, vacuum service, condensate handling and cleaning connections. Ask the bidder to mark battery limits on a process flow diagram: which pumps, instruments, pipework and utilities are included? A heat exchanger price alone does not describe an operable installation.
Define the operating envelope
Document normal, minimum and maximum feed conditions separately. Include how long the plant must remain at reduced throughput and what happens during interruptions. Ask the designer to explain the planned start-up sequence, product diversion and recovery from loss of feed. These questions are a procurement checklist, not operating instructions.
Review the next interface
Before approving a concept, ask where separated vapor goes, how concentrate leaves, and how unsuitable product is isolated. Confirm that the downstream process can accept the proposed concentration and temperature. Require an agreed test method for product quality instead of a generic claim of gentle treatment.
Technical references
Define the duty before the equipment.
Prepare feed, product and utility information in one local project brief.