PROPYLENE EVAPORATORS
Engineered for petrochemical propylene refrigeration cycles, PP/PE production, and gas fractionation. Shell & tube, falling film, and thermosiphon configurations. ASME & PED certified. HTRI-validated thermal design. Capacities from 200 kW to 12,000 kW duty.
PROPYLENE PROPERTIES
- –47.6 °C — Boiling point (1 atm)
- 91.9 °C — Critical temperature
- 4.60 MPa — Critical pressure
- 42.08 g/mol — Molecular weight (C₃H₆)
- R-1270 — Refrigerant designation
- GWP < 2 — Near-zero global warming potential
WHAT IS A PROPYLENE EVAPORATOR?
Critical heat transfer equipment for converting liquid propylene (R-1270) to the gas phase in petrochemical refrigeration and process systems.
Propylene evaporators are pressure vessels designed to absorb heat from process streams — cooling those streams while vaporizing liquid propylene on the refrigerant side. They operate at evaporating temperatures typically between –40 °C and –5 °C, corresponding to suction pressures of 0.12–0.55 MPa.
These units form the core of propylene refrigeration systems used across petrochemical complexes for reactor cooling, condensation duty, and storage temperature maintenance. Propylene (R-1270) is selected as the refrigerant because of its thermodynamic efficiency at moderate cryogenic temperatures, low GWP, and compatibility with standard carbon steel and stainless steel construction.
- Flooded shell & tube — Most common type, high heat transfer coefficient, liquid propylene on the shell side
- Falling film — Higher efficiency, compact footprint, reduced refrigerant charge
- Thermosiphon — Natural circulation, no pump required, lower maintenance
- Plate heat exchanger — Small-duty applications, compact, easy to clean
APPLICATIONS
Propylene evaporators serve as the cold-end heat exchanger in refrigeration loops across multiple petrochemical and energy processes.
PROPYLENE REFRIGERATION SYSTEMS
Central chiller duty in ethylene crackers, PDH/MTO plants, and chemical complexes. Evaporating temperatures –40 °C to –5 °C. Single or multi-stage compression loops.
POLYPROPYLENE (PP) PRODUCTION
Reactor cooling in Spheripol, Unipol, and Novolen PP processes. Propylene evaporator removes polymerization heat to maintain reactor temperature control.
LDPE / HDPE PLANT COOLING
Process gas cooling and condensation duty in polyethylene plants. Evaporator provides stable cold utility for separator and purge gas systems.
GAS FRACTIONATION UNITS
Condenser and reboiler duty in de-propanizer, de-ethanizer, and C3 splitter columns. Propylene evaporator provides controlled cooling at target column pressures.
LPG STORAGE TERMINALS
Propylene and propane storage tank pressure maintenance. Evaporator cools and reliquefies boil-off gas to maintain tank operating pressure.
CASCADE PRE-COOLING
Propylene evaporator as high-stage pre-cooler in propylene/ethylene cascade systems. Reduces ethylene compressor duty and improves overall system COP.
DESIGN STANDARDS
All propylene evaporators designed and fabricated to international pressure equipment codes.
- ASME BPVC Section VIII Div.1 — U-Stamp pressure vessels
- TEMA — Shell and tube exchanger mechanical standards (BEM, AES, BEU, etc.)
- API 660 — Shell and tube heat exchangers for petroleum and petrochemical
- PED 2014/68/EU — CE marking for European market
- GB 150 / GB 151 — Chinese national pressure vessel and heat exchanger standards
- HTRI Xist — Thermal design validated by HTRI simulation software
MATERIALS OF CONSTRUCTION
Material selection matched to service temperature, pressure, and corrosion environment.
- SA516 Gr.70 (Normalized) — Standard shell and head material for propylene service to –45 °C
- SA516 Gr.60 (Impact Tested) — Shell components requiring MDMT compliance below –29 °C
- 304L / 316L Stainless — Tubes, tubesheets, and internals for corrosion resistance and low-temperature toughness
- SA333 Gr.6 — Low-temperature carbon steel piping
- SA350 LF2 — Flanges for low-temperature service
- Copper alloy tubes — Optional for enhanced thermal conductivity in specific configurations
TYPICAL SPECIFICATIONS
Representative parameters for propylene evaporator configurations. All designs are project-specific based on process data sheets.
| Parameter | Shell & Tube (Flooded) | Falling Film | Thermosiphon |
|---|---|---|---|
| Duty range | 500 – 12,000 kW | 200 – 8,000 kW | 300 – 5,000 kW |
| Evaporating temperature | –40 °C to –5 °C | –40 °C to –5 °C | –35 °C to –5 °C |
| Design pressure (shell) | 2.5 MPa typical | 2.5 MPa typical | 2.5 MPa typical |
| Heat transfer area | 10 – 500 m² | 10 – 300 m² | 10 – 200 m² |
| Tube material | 304L / 316L / Carbon steel | 304L / 316L | 304L / Carbon steel |
| TEMA type | BEM / AES / BEU | BEU / NEN | BEM / AES |
| Refrigerant charge | Highest (shell-side flooded) | Lowest (thin film, reduced inventory) | Moderate (natural circulation) |
LMART CAPABILITIES
- ASME U — NBIC-registered fabrication
- 600+ PQR — All low-temp weld grades covered
- HTRI Xist — Licensed thermal design software
- 38,000 m² — Workshop in Zhangjiagang
- 6 Class Societies — DNV, ABS, BV, LR, NK, CCS
- PED 2014/68/EU — CE marking for EU export
EPC DELIVERY SCOPE
Full documentation and witness testing as standard for all propylene evaporator orders.
- Thermal design report — HTRI Xist simulation with duty verification
- Mechanical design — ASME VIII or PED compliant, with FEA for critical nozzle loads
- Material test certificates — EN 10204 Type 3.1 / 3.2 as required
- NDE and hydrostatic test — 100% RT/UT on pressure welds, hydrotest per code
- FAT witness — EPC / TPI witness plan agreed at kickoff
- Vendor data book — Closeable turnover package with all QA/QC records
FREQUENTLY ASKED QUESTIONS
Common questions from EPC engineers and procurement teams about propylene evaporators
What is a propylene evaporator and how does it work?
A propylene evaporator is a heat exchanger that vaporizes liquid propylene (R-1270) by absorbing heat from a process stream. Liquid propylene enters at low pressure (typically 0.12–0.55 MPa) and evaporates at temperatures between –40 °C and –5 °C. The latent heat absorbed during this phase change cools the process fluid on the other side. This is the core cooling mechanism in propylene refrigeration systems used across petrochemical plants.
What types of propylene evaporators are available?
Four main types: (1) Flooded shell & tube — the most common, with liquid propylene flooding the shell side for high heat transfer coefficients. (2) Falling film — propylene flows as a thin film over tube surfaces, offering higher efficiency with reduced refrigerant charge. (3) Thermosiphon — uses natural convection for circulation, eliminating the need for a refrigerant pump. (4) Plate heat exchangers — used for smaller duties where compactness and ease of cleaning are priorities.
What materials are used for propylene evaporator construction?
Shell and heads are typically SA516 Gr.70 (normalized) for service to –45 °C, or SA516 Gr.60 (impact tested) for lower MDMT requirements. Tubes and tubesheets are commonly 304L or 316L stainless steel for corrosion resistance and low-temperature toughness. Flanges are SA350 LF2 for low-temperature carbon steel service. Piping is SA333 Gr.6. Material selection is finalized based on project-specific process conditions and code requirements.
What design codes and certifications does LMART comply with?
LMART holds ASME U Stamps (NBIC-registered) for pressure vessel fabrication, and PED 2014/68/EU certification for CE marking. Propylene evaporators are designed to ASME VIII Div.1, TEMA standards, and API 660 as applicable. We maintain 600+ welding procedure qualifications (PQR) covering all material grades used in propylene service. Classification society approvals include DNV, ABS, BV, LR, NK, and CCS. ISO 9001 quality management system certified.
How does LMART validate the thermal design?
All propylene evaporator thermal designs are validated using HTRI Xist software, the industry-standard tool for shell-and-tube heat exchanger simulation. We model the two-phase propylene evaporation with accurate prediction of heat transfer coefficients, pressure drop, and flow distribution. The HTRI report is included in the vendor data book and can be reviewed by the client’s process engineering team during the design approval phase.
What is the typical lead time for a propylene evaporator?
Standard propylene evaporators: 12–20 weeks from design approval to ex-works, depending on size, material procurement, and third-party inspection requirements. Large or special-material units may require 20–28 weeks. Documentation deliverables include GA drawings, data sheets, material test certificates (EN 10204 3.1/3.2), weld maps, NDE reports, hydrostatic test certificates, HTRI thermal reports, and operation/maintenance manuals.
DISCUSS YOUR PROPYLENE EVAPORATOR PROJECT
Submit your process data sheet or key parameters and our engineering team will respond with a data-backed technical proposal within 24–48 hours.