Dual Effect External Circulation Evaporator

Double-Effect Natural Circulation Evaporator — Overview

I. Working Principle

The equipment consists of a first-effect heating-separation chamber, second-effect heating-separation chamber, condenser, vacuum pump unit, and circulation piping. It utilizes vacuum gradient to create a two-stage pressure differential for cascaded heat utilization: Fresh steam enters the first-effect shell side to heat the feed liquid, which rises naturally due to reduced density into the first-effect separation chamber for flash evaporation, producing high-temperature secondary steam. This secondary steam is then directly fed into the second-effect heater shell side as the heating source, fully recovering waste heat and significantly reducing fresh steam consumption. The second-effect secondary steam enters the condenser for solvent recovery. Both effects rely on temperature and density differences for natural circulation without circulation pump disturbance, ensuring gentle liquid flow. The material can be concentrated continuously in series across both effects, progressively increasing concentration until the target is reached for automatic discharge. The entire process operates under low-temperature negative pressure, minimizing thermal degradation of heat-sensitive components.

II. Structure & Components

  1. First & Second-Effect Shell-and-Tube Heating Chambers: Vertical long tube bundle heat exchange structure with ample heating area. Shell-side steam heating with external insulation to reduce heat loss, ensuring uniform and stable temperature rise.

  2. Natural External Circulation System: Self-circulation driven by material temperature and density differences — no circulation pump, no mechanical shear. Low operating noise and minimal maintenance requirements.

  3. Two-Stage Vapor-Liquid Separation Chambers: Large-volume separation cavities with built-in corrugated demister and mist eliminator to intercept entrained droplets, reducing material loss.

  4. Condensation & Solvent Recovery System: Shell-and-tube condenser with solvent storage tank. High recovery rates for water, ethanol and other solvents, enabling recycling and reuse for production cost savings.

  5. Multi-Stage Vacuum Pump Unit: Stably maintains two-stage negative pressure gradient, enabling low-temperature evaporation to protect heat-sensitive active substances such as polysaccharides, volatile oils and alkaloids.

  6. PLC Intelligent Control System: Interlocked control of temperature, vacuum level, feed flow rate and liquid level. Automatic parameter recording and storage, supporting continuous automated production.

  7. CIP In-Place Cleaning Interface: Pre-configured throughout the entire unit with zero cleaning dead zones. Convenient disassembly and cleaning, meeting GMP cleaning validation requirements.

Double-Effect Evaporator — Technical Specifications (SJN Series)