Hengli Petrochemical — Ethylene Tank Farm (2018) — Direct Cooling System for Ethylene Storage
By Qiangbin Chu · Sales Manager & Operations Lead
Hengli Petrochemical operates one of China's largest integrated refining-petrochemical complexes on Changxing Island in Dalian. The facility's ethylene production feeds downstream units including HDPE, LLDPE, EO/EG, and styrene. Large-volume ethylene storage tanks at atmospheric pressure require continuous refrigeration to maintain the liquid ethylene at approximately −104 °C and minimize boil-off losses.
| Client | Hengli Petrochemical (Changxing Island, Dalian) |
| Plant / Unit | Ethylene Tank Farm |
| Equipment | Direct Cooling System × 1 |
| Design Code | GB |
| Cooling Capacity | 1,200 kW |
| Motor Power | 1,000 kW |
| Refrigerant | Propylene (R1270) |
| Process Medium | Ethylene |
| Design Institute | Yangzi Petrochemical Research Institute |
| Year | 2018 |
Customer Background
Hengli Petrochemical operates one of China’s largest integrated refining-petrochemical complexes on Changxing Island in Dalian. The facility’s ethylene production feeds downstream units including HDPE, LLDPE, EO/EG, and styrene. Large-volume ethylene storage tanks at atmospheric pressure require continuous refrigeration to maintain the liquid ethylene at approximately −104 °C and minimize boil-off losses.
Direct cooling systems condense ethylene vapour back to liquid phase without an intermediate brine loop, improving thermodynamic efficiency compared to indirect systems. However, the equipment must operate reliably at cryogenic temperatures with ethylene — a flammable gas — as the direct process medium, requiring stringent material selection and safety engineering.
The Changxing Island ethylene tank farm serves as a buffer between the upstream cracker and multiple downstream consuming units. Maintaining reliable low-temperature storage is critical for uninterrupted plant operation — any loss of refrigeration capacity could force the cracker to reduce throughput or flare ethylene product, with significant economic consequences.
Challenges and Engineering Requirements
Process Temperature Control in petrochemical processing
Hengli Petrochemical required precise low-temperature cooling for Direct Cooling System × 1 service in the petrochemical processing sector. The brine chiller system must maintain stable outlet temperatures within narrow tolerances despite variable process heat loads. Fluctuations in feed composition, ambient temperature swings, and seasonal load variations all affect the refrigeration duty — the system must respond to these changes while protecting compressor operation from surge and liquid carryover.
Refrigerant Selection and Safety
The choice of Propylene (R1270) reflects the balance between thermodynamic efficiency at the target evaporating temperature, compatibility with the plant’s existing refrigerant infrastructure, and safety classification under the applicable code. Each refrigerant brings specific considerations: flammability limits for hydrocarbon refrigerants, operating pressure ranges that affect component sizing, and oil miscibility that influences compressor lubrication system design.
Integration with EPC Engineering
The chiller packages were specified and documented by Yangzi Petrochemical Research Institute as part of a larger process unit. This means every interface — brine supply/return connections, electrical load requirements, control signal protocols, and physical footprint — must match the EPC’s plot plan and P&ID exactly. Any deviation requires formal design change management, adding time and cost to the project.
Why Hengli Petrochemical Selected Lmart
Integrated refrigeration package capability. Lmart designs and manufactures complete refrigeration systems — compressor selection, heat exchanger sizing, piping layout, control logic, and skid-frame engineering — as a single-source supplier. This eliminates the interface risks that arise when the chiller vendor, vessel fabricator, and system integrator are separate companies.
Process refrigerant experience. Lmart has delivered refrigeration packages using propylene, propane, ammonia, R134a, and other process refrigerants across petrochemical, chemical, and marine applications. This experience base means the engineering team understands the specific requirements of each refrigerant — safety classifications, oil management, capacity control methods — without a learning curve.
Repeat performance. Lmart has delivered equipment to Hengli Petrochemical and similar clients in the petrochemical processing sector, demonstrating consistent quality and on-time delivery performance across multiple projects.
Technical Scope and Specifications
The direct cooling system provides 1,200 kW of refrigeration at cryogenic conditions using a propylene (R1270) refrigerant cascade. A 1,000 kW motor drives the main screw compressor. The propylene circuit condenses ethylene vapour in a shell-and-tube heat exchanger, returning liquefied ethylene to the storage tank.
Key design parameters include:
- Cryogenic service: Evaporator and associated piping designed for ethylene at approximately −104 °C, requiring impact-tested low-temperature carbon steel or stainless steel construction
- High motor power: The 1,000 kW compressor motor reflects the substantial temperature lift required from ethylene condensation temperature to the propylene condenser rejection temperature
- Flammable gas handling: Ethylene (process side) and propylene (refrigerant side) are both flammable — the package design incorporates gas detection, emergency shutdown, and hazardous area electrical classification
- Yangzi Petrochemical Research Institute engineering: Equipment manufactured to the institute’s technical specifications for ethylene tank farm refrigeration systems
The system was delivered as a complete package including compressor, condenser, evaporator, oil separation system, control panel, and interconnecting piping — factory-tested before shipment to the Changxing Island site.
Delivery and Quality Assurance
The direct cooling system was factory-assembled and tested at Lmart’s Zhangjiagang facility before transport to the Changxing Island site. All cryogenic components were subject to low-temperature impact testing per GB/T 229 to verify material toughness at the design minimum temperature. Pressure-containing components underwent hydrostatic testing, and the complete system was subjected to a leak test before shipment.
The ethylene tank farm project was part of a broader package of three refrigeration/compression orders from Hengli Petrochemical, including HDPE brine chillers and PP brine chillers delivered in the same period. The Yangzi Petrochemical Research Institute’s engineering specifications were met in full, including documentation in the format required for integration with the plant’s distributed control system (DCS).
Results and Business Impact
Lmart successfully delivered 1 units of Direct Cooling System × 1 to Hengli Petrochemical, meeting the project’s quality, schedule, and documentation requirements. The equipment was manufactured to GB standards, with full documentation packages accepted by the client and applicable inspection authorities.
This project reinforces Lmart’s position as a qualified manufacturer for petrochemical processing applications, demonstrating the company’s ability to deliver equipment that meets international quality and certification standards.
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Customer Voice
“The equipment was delivered on schedule and the documentation package was complete. The quality of fabrication met our inspection requirements.”
— Hengli Petrochemical project team (paraphrased from project review)
Note: Lmart respects client confidentiality. Specific contact references are available upon request during the qualification process.