Molecular Sieve
Dehydration Skid
Sinopec Northwest Bureau -- Shunbei No. 5 Joint Station
Key Facts
- Client
- Sinopec Northwest Bureau
- Location
- Shunbei Field, Xinjiang, China
- Equipment
- Twin-Tower Molecular Sieve Dehydration Skid
- Application
- Deep gas dehydration for Shunbei Ordovician reservoir gas
- System Design
- Twin-tower adsorption-regeneration cycling
- Control
- Automatic PLC cycle control with online dew point monitoring
- Manufactured by
- LINSON OIL, Dongying, Shandong, China
The Shunbei Ordovician Reservoir
What Makes This Gas Technically Demanding
The Shunbei Oilfield in the Xinjiang Tarim Basin is one of China's most technically significant upstream developments. The field produces oil and gas from the Ordovician carbonate formation -- a deep, fractured carbonate reservoir at burial depths exceeding 7,000 metres. At this depth, the reservoir conditions are extreme:
Reservoir Depth and Pressure
Burial depth beyond 7,000 metres places the Shunbei reservoir among the deepest producing formations in China. The reservoir pressure at this depth is correspondingly very high -- requiring surface equipment, including the gas processing system at the joint station, to be designed for operating and design pressures significantly above those of most conventional upstream gas processing applications.
Elevated H₂S Content
Gas from the Shunbei Ordovician reservoir contains hydrogen sulfide (H₂S) above the threshold that requires sour service material selection and design compliance. This affects every piece of equipment that contacts the gas stream: vessel materials must be selected to resist H₂S stress corrosion cracking (per NACE MR0175 / ISO 15156); weld procedures require post-weld heat treatment where applicable; instrument wetted parts must be H₂S-compatible. A molecular sieve dehydration system for sour gas is more demanding to design and specify than one for sweet gas service.
Deep Dehydration Requirement
The downstream processing of Shunbei gas -- which includes compression and gas export -- requires the gas to meet a water dew point specification that cannot be achieved by glycol (TEG) dehydration alone in these service conditions. Molecular sieve dehydration was specified to achieve the required dew point reliably and consistently, regardless of the variability in inlet gas conditions associated with a developing deep carbonate reservoir.
The Sinopec Procurement Context
Sinopec Northwest Bureau operates one of China's most technically demanding upstream gas portfolios. Equipment supplied to the Northwest Bureau's facilities is procured through a rigorous supplier qualification and tendering process -- technical specification compliance, manufacturing capability audit, and quality system review are all part of the supplier selection process. Selection for this project required LINSON OIL to demonstrate that its molecular sieve design and fabrication capability was appropriate for the specific and demanding conditions of the Shunbei reservoir gas.
The Engineering Solution
Twin-Tower Molecular Sieve Dehydration System Design
Process Flow Diagram: Adsorption and Regeneration Cycles
Regeneration Gas System
The regeneration gas circuit uses a slip stream of the dry product gas, heated to the regeneration temperature (250°C-320°C) in an electric regeneration gas heater. The hot gas flows through the saturated sieve bed in the reverse direction to adsorption flow (countercurrent regeneration), desorbing the water. The spent regeneration gas is cooled, water vapour condenses and is knocked out in a drum, and the cooled gas is returned to the inlet. The entire circuit operates automatically under PLC control.
Online Dew Point Monitoring
An online chilled mirror or aluminium oxide dew point analyser at the system outlet provides continuous verification of the dehydrated gas dew point. If the measured dew point rises above the alarm setpoint, the PLC can initiate an early tower switchover before the outlet specification is exceeded, and generate an alarm.
Data is transmitted to the joint station SCADA system, providing real-time visibility of dehydration performance without requiring a local visit to the skid.
Sour Service Design Compliance
- Vessel materials selected and verified for H₂S stress corrosion cracking resistance per NACE MR0175 / ISO 15156
- Weld hardness testing after post-weld heat treatment (where required)
- All instrument wetted materials specified for H₂S-compatible grades
- Valve seat and seal materials compatible with H₂S-bearing sour gas
Technical Scope Summary
Certification Relevance
- A2 Pressure Vessel License Adsorber vessels under high pressure, sour gas service
- GC2 Piping License All skid piping under high pressure, sour service conditions
- NACE MR0175 / ISO 15156 Sour service material selection and fabrication compliance
- CNAS Accredited Laboratory Vessel weld NDT; hydrostatic testing; material chemical analysis
- Sinopec HSE Certified Qualification required for supply to Sinopec Northwest Bureau projects
- ISO 9001:2015 Quality management system covering the full project scope
What Was Delivered
| Component | Description |
|---|---|
| Adsorber vessels (×2) | Twin-tower; pressure vessels per GB 150; sour service material; sized for Shunbei gas flow rate and H₂S content |
| Molecular sieve adsorbent | Selected type and grade for sour gas dehydration duty; bed volume with H₂S competition margin |
| Switching valve manifold | Pneumatically actuated ball valves (high-cycle duty rating); automatic PLC sequencing |
| Electric regeneration gas heater | Sized for regeneration duty at design cycle time |
| Regeneration gas cooler | Air-cooled or water-cooled; sized for regeneration gas flow |
| Regeneration gas knockout drum | Condensate removal from cooled regeneration gas |
| Online dew point analyser | Continuous measurement; integrated with PLC switchover logic and SCADA |
| PLC control panel with HMI | Full automatic cycle control; alarm management; dew point alarm and early switchover logic |
| Structural skid frame | All equipment, piping, and instrumentation on common structural frame |
| All skid piping | GC2 licensed; sour service material and weld procedure; ASME B31.3 compliant |
| FAT | Full system cycle simulation; dew point analyser integration test; all alarm and shutdown functions |
The Significance of the Shunbei Reference
Sour Gas Molecular Sieve Design
Designing a molecular sieve dehydration system for sour gas service -- with the correct sieve type, bed volume margin for H₂S competition, and sour service material specification throughout -- requires process engineering knowledge that goes beyond a standard sweet gas molecular sieve application. The Shunbei project demonstrates this capability in a real, demanding application for a rigorous NOC client.
Sinopec Northwest Bureau Qualification
Sinopec Northwest Bureau's supplier qualification process is not a registration exercise. It involves review of the manufacturer's quality management system, manufacturing facility audit, technical competence assessment for the specific equipment category, and HSE compliance verification. Suppliers who do not meet these requirements are not awarded contracts regardless of price. LINSON OIL's qualification and delivery record with Sinopec Northwest Bureau represents sustained technical and quality performance under this framework.
High-Pressure Equipment for Deep Reservoir Gas
The Shunbei reservoir's extreme depth means the surface operating pressure at the joint station is substantially higher than most conventional upstream gas processing applications. The molecular sieve skid was designed for this operating pressure, requiring vessel design and fabrication at pressure ratings that fewer manufacturers are licensed and capable of producing.
Deep Dehydration for Sour or High-Pressure Gas?
If your project involves molecular sieve dehydration of high-pressure, sour, or otherwise demanding gas -- whether for pipeline export, LNG feed, cryogenic processing, or other deep dehydration duty -- the Shunbei project is the most directly relevant reference LINSON OIL can offer. Send us your gas composition and dew point requirement and our process engineers will assess the design requirements for your specific application within 1-2 business days.
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