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I. Product Overview
The absorption-based tertiary Vapor recovery device is a highly efficient and environmentally friendly equipment designed to address the issue of Vapor volatilization in oil depots, refining enterprises, and large gas station storage tanks. This product utilizes the principle of differences in solubility of various components in the Vapor mixture within an absorbent (such as diesel or gasoline). Through countercurrent gas-liquid contact, volatile organic compounds (VOCs) are separated and recovered from the mixed gas. The treated exhaust gas meets emission standards, and the recovered oil can be directly reused.
This product complies with the requirements of the "Emission Standard of Air Pollutants for Gas Stations" (GB 20952-2020) and the "Emission Standard of Air Pollutants for Oil Depots" (GB 20950). It can be used in combination with adsorption and membrane separation methods to achieve an emission concentration ≤25g/m³ (national standard), meeting the environmental compliance requirements of oil depots, refineries, and large storage and transportation enterprises.
Important Note: The absorption method is relatively less used in tertiary Vapor recovery at gas stations, mainly because its recovery rate is relatively low when used alone (approximately 80%), making it difficult to meet current national standards. The core applications of absorption methods are concentrated in large and medium-sized storage and transportation sites such as oil depot loading platforms, refineries, and chemical enterprises. It is typically used as the first-stage pretreatment unit in combined processes, operating in conjunction with adsorption and membrane separation methods. In gas station scenarios, absorption methods are generally not used in pure absorption, but rather as part of a condensation + absorption or absorption + adsorption combined process.
II. Technical Principles
2.1 Core Technical Principles
Absorption-based Vapor recovery technology separates Vapor from air based on the solubility of each component in the mixed Vapor in the absorbent. Using lean oils such as diesel as the absorbent, the Vapor generally come into countercurrent contact with the absorbent sprayed from the top of the absorption tower. The absorbent selectively absorbs hydrocarbon components, and the unabsorbed gas is discharged through a flame arrester. The absorbent enters a vacuum desorption tank for desorption, enriching the Vapor for further absorption with oil products.
Absorption Principle: Inside the absorption tower, Vapor enter from the bottom and come into full contact with the absorbent (such as low-temperature gasoline or diesel) sprayed from the top of the tower in the packing layer. Based on the principle of "like dissolves like," the absorbent has a strong solubility for hydrocarbon molecules, while air has extremely low solubility in the absorbent. Hydrocarbon molecules transfer from the gas phase to the liquid phase and are captured by the absorbent; air is discharged from the top of the tower.
2.2 Workflow
Main Flow (Absorption + Desorption Cycle):
Oil-containing waste gas → Absorption tower → Unabsorbed gas → Flame arrester → Compliant emission
↓
Absorbent absorbs Vapor → Enriched absorbent → Vacuum desorption tank
↓
Enriched Vapor → Oil absorption/return to tank
↓
Lean absorbent recycling
Process Flow Description:
Absorption Stage: Oil-containing waste gas enters the absorption tower through the collection system. The absorbent is sprayed down from the top of the tower, and the gas and liquid phases come into countercurrent contact. Hydrocarbon components are selectively dissolved and absorbed by the absorbent. The unabsorbed clean gas is discharged from the top of the tower and discharged after passing through the flame arrester to meet emission standards.
Desorption Stage: The rich absorbent, having absorbed Vapor , enters a vacuum desorption tank. Under vacuum conditions, it is heated and desorbed, releasing the absorbed Vapor to form a high-concentration Vapor mixture.
Recovery Stage: The desorbed high-concentration Vapor mixture is transported to an oil absorption tower (or directly returned to the tank), where it is absorbed by the liquid oil within the tower, achieving resource recovery. The absorbent, after desorption and regeneration, becomes a lean absorbent and is recycled back to the absorption tower for reuse.
2.3 System Composition
The main core components of the absorption-based tertiary Vapor recovery unit include:
|
Component Names |
Functional Description |
|
Absorber Tower |
Core processing unit, the gas-liquid contact area, with a packing layer (or tray) inside the tower to increase the gas-liquid contact area and improve absorption efficiency. Generally a vertical structure, offering high processing capacity flexibility. |
|
Vacuum Desorption Tank |
Desorbs Vapor from the rich absorbent under vacuum conditions, achieving absorbent regeneration and oil/gas enrichment. |
|
Absorbent Storage Tank |
Stores lean and rich absorbents to ensure continuous system operation. |
|
Circulation Pump (Lean Oil Pump/Rich Oil Pump) |
Transports absorbent from the absorbent storage tank to the top of the absorption tower for spraying, and sends rich absorbent to the desorption tank. |
|
Refrigeration Unit (Optional) |
Reduces the absorbent temperature to approximately 5°C; low temperature helps improve absorption efficiency. |
|
Vacuum Pump |
Provides a vacuum environment for the desorption tank, with a vacuum level below 5.3 kPa, ensuring effective desorption. |
|
PLC Control System |
Fully automatic control, real-time monitoring of absorbent level, temperature, pressure, and other parameters, automatically adjusting the absorbent circulation rate. |
|
Flame Arrestor |
Installed on the discharge pipeline to prevent flame propagation and ensure safety. |
III. Key Technological Advantages
Advantages
- Mature and Stable Process: Absorption methods have a long history of application in the petrochemical industry and are highly mature.
- Lower Investment Costs: Compared to cryogenic condensation processes, initial equipment investment is lower, and recovery results are stable.
- Large Processing Capacity and Strong Concentration Adaptability: Suitable for high-concentration Vapor treatment, insensitive to fluctuations in exhaust gas concentration, particularly suitable for large-volume intermittent emissions such as oil depot loading.
- High Operational Flexibility: Adaptable to 0-100% operating condition fluctuations, especially suitable for intermittent loading situations.
- Direct Utilization of Recovered Resources: Absorbed rich oil can be directly returned to storage tanks, resulting in direct economic benefits.
- High Recovery Rate: In the combined absorption + adsorption process, the recovery rate of heavy hydrocarbon (C3 and above) components is close to 100%.
Limitations:
- Low recovery rate when used alone: Pure absorption methods typically only achieve a recovery rate of around 80%, which is insufficient to meet current national standards (treatment efficiency ≥95%, emission concentration ≤25g/m³).
- Large footprint: The equipment requires a relatively large installation space.
- Absorbent consumption: Absorbent is consumed to some extent and needs continuous replenishment; improper absorbent selection may affect long-term operating efficiency.
- Large system pressure drop: Can reach approximately 5000 Pa, requiring a high-pressure blower.
IV. Technical Parameters
|
Parameter Items |
Technical Specifications |
Description |
|
Processing Capacity |
200～10000 Nm³/h (customizable) |
Covering all needs from small and medium-sized gas stations to large oil depots |
|
Absorbent Type |
Low-grade gasoline, light diesel oil, kerosene, special absorbent |
Selection based on Vapor composition |
|
Absorbent Temperature |
0℃～10℃ (refrigeration optional) |
Low-temperature absorption helps improve absorption efficiency |
|
Absorbent Circulation Ratio |
Feed gas:absorbent = 10:1～5:1 (volume ratio) |
Determined by Vapor concentration and absorbent performance |
|
Vacuum Desorption Pressure |
≤13.3 kPa |
Ensuring complete desorption |
|
Theoretical Plate Count of Absorber Tower |
9～13 blocks |
Affecting absorption efficiency |
|
System Pressure Drop |
Approximately 5000 Pa |
Requires appropriate air pressure and blower configuration |
|
Processing Efficiency (Pure Absorption) |
≥80% (used alone) |
Complete emission standards require combined adsorption processes |
|
Combined Process Efficiency |
≥95%～99.9% |
Absorption + adsorption combination can achieve national Class A standards |
|
Emission Concentration |
≤60 mg/m³ (combined process) |
Non-methane total hydrocarbons |
|
Explosion-proof Rating |
Ex d IIB T4 |
Suitable for flammable and explosive locations |
|
Control Method |
PLC fully automatic control |
Supports remote data transmission and online monitoring |
V. Application Scenarios
|
Application Areas |
Specific Scenarios |
Recommended Process Configurations: |
|
Gas stations |
Tertiary Vapor recovery at gas stations with annual sales exceeding 5,000 tons |
As a pretreatment unit in a combined process, used in conjunction with adsorption: |
|
Oil depots |
Vapor recovery in refined oil tank areas and dispensing platforms |
Absorption + Adsorption Combined Process (Mainstream Solution) |
|
Oil terminals |
Vapor recovery during tanker loading and unloading operations |
Low-Temperature Absorption + Adsorption Combined Process |
|
Refineries/chemical plants |
Atmospheric and vacuum distillation gas, Vapor from loading platforms, and chemical exhaust gases |
Multi-Stage Combination of Absorption + Membrane Separation + Adsorption |
|
Railway/highway loading and unloading systems |
High-concentration Vapor displaced during tanker loading |
Ambient Temperature and Pressure Absorption Recovery Unit |
VI. Combined Process Routes
Single absorption methods are insufficient to meet increasingly stringent emission standards; therefore, the industry typically employs combined processes to achieve compliance. The following are some mainstream combined absorption process schemes:
|
Combined processes: |
Process Flow: |
Key Features: |
|
Absorption + Adsorption |
Absorber pretreatment (removing over 50% of Vapor ) → Adsorption tower deep purification → Emission meeting standards |
This is currently the most widely used and mature technology in oil depots and loading/unloading systems, boasting advantages such as low energy consumption and high processing capacity. |
|
Absorption + Membrane Separation + Adsorption |
Absorber pretreatment → Membrane module separation and purification → Adsorption tank deep purification |
Aromatics recovery can reduce non-methane hydrocarbon (NMHC) emissions to 11.36 mg/m³, and at loading/unloading stations, to 13.30 mg/m³, meeting the national Class A enterprise standard. |
|
Low-temperature absorption + Adsorption gradation |
Absorbent cooled to 5℃ enters the absorber → Adsorption tank (three-stage graded material: mesoporous + microporous + ultra-microporous) deep purification |
This technology has been included in the recommended category of the 2025 National Pollution Prevention and Control Technology Guidance Catalogue; the absorption tower can absorb more than 50% of Vapor ; dual tanks operate alternately, with a processing capacity of 200-10000 m³/h. |
|
Absorption + Condensation + Adsorption |
Absorber bulk pretreatment → Condensation liquefaction recovery → Adsorption deep purification |
Utilizing a multi-stage combination to gradually reduce load, it is suitable for treating waste gases with complex compositions and drastic concentration fluctuations. |
VII. Mainstream Products and Specifications in the Market
7.1 Representative Products
|
Companies |
Product Model |
Processing capacity: |
Features |
Applications |
|
Shandong Yingda Environmental Protection |
SDYD-1000 / YD-1000 |
30 m³/h |
Uses lean oils such as diesel as the absorbent; countercurrent spraying at the top of the absorption tower; desorption occurs in a vacuum desorption tank. |
Gas stations, oil depots, oil refineries |
|
Sinopec Safety Engineering Research Institute |
Low-Temperature Absorption - Pore Size Gradation Material Adsorption |
200-10000 m³/h |
The absorbent is cooled to 5°C; a three-stage adsorption gradient material is used. |
Oil field development, crude oil storage and transportation, refining |
|
Shenzhen Autowell |
Absorption + Adsorption Method for Vapor Recovery System |
Customizable |
Parallel dual adsorption tanks + dry vacuum pump + absorption tower + circulation pump. |
Oil refineries, oil storage depots, chemical gas recovery |
|
Jinan Qiankun Environmental Protection |
QKHB-YY |
Customizable |
Uses a high gravity bed or absorption tower as the reactor; absorbs lean oils such as diesel. |
Petrochemical, chemical, oil depots |
7.2 Selection Recommendations
|
Project Scale |
Recommended processing capacity |
Recommended Processes |
Explanation |
|
Small Gas Stations (2000-3000 tons/year) |
6～10 m³/h |
Condensation + Adsorption (Absorption method not recommended alone) |
Absorption methods have limited effectiveness when used alone at gas stations |
|
Large Gas Stations (3000-8000 tons/year) |
10～20 m³/h |
Condensation + Adsorption as the main process, absorption as an auxiliary process |
- |
|
Small and Medium-Sized Oil Depots/Loading Platforms |
200～500 m³/h |
Absorption + Adsorption combination |
Absorption towers serve as the primary pretreatment unit |
|
Large Oil Depots/Shipping Wharves |
500～2000 m³/h |
Low-temperature absorption + adsorption staged combination |
Recommended scheme from the National Encouraged Technologies Catalogue |
|
Refining and Chemical Enterprises/Chemical Waste Gas |
500～10000 m³/h |
Absorption + Membrane separation + Adsorption multi-stage combination |
Targeting complex compositions and drastic concentration fluctuations |
7.3 Absorbent Selection Guide
The choice of absorbent directly affects the absorption efficiency and should be determined comprehensively based on the Vapor composition and the target recovery rate:
|
Absorbent Types |
Applicable Scenarios |
Features |
|
Low-octane gasoline |
Oil depot gasoline tank area, loading platform |
Raw materials are readily available, homogeneous in composition, recyclable, and can be directly returned to storage tanks. |
|
Light diesel oil |
Gasoline vapor recovery, chemical storage and transportation |
Low price and good absorption performance, but flash point control is necessary to ensure safety. |
|
Kerosene |
Aviation kerosene depot, chemical products |
Excellent absorption performance, but limited application range. |
|
Special absorbent (e.g., AbsFOV-97) |
Scenarios with high vapor concentration and high recovery rate requirements |
Pilot-scale recovery rate reached 97%, and the recovered gasoline quality met usage requirements. |
VIII. Installation Requirements
8.1 Installation Conditions
- Installation at gas stations or oil depots that have completed secondary Vapor recovery system upgrades.
- A foundation must be reserved for the equipment. Installation must be in a well-ventilated, dedicated area away from heat sources.
- A 380V/50Hz three-phase power supply is required; power output depends on the processing capacity.
- Gas connection: DN40～DN200 flange connection (depending on processing capacity).
- The exhaust pipe outlet should be at least 4 meters above ground level, away from areas with high personnel activity.
- The absorbent storage tank must have a dosing port, located above ground level for easy operation.
8.2 Installation Precautions
- The equipment should be installed horizontally to ensure uniform gas-liquid contact within the absorption tower.
- Electrical wiring must comply with explosion-proof area construction specifications (GB 3836 series).
- The packing material in the absorption tower must be checked regularly; any blockages should be cleaned or replaced promptly.
- Pipeline connections must be airtight to prevent Vapor leakage.
- The absorbent tower liquid level control should be within the safe range of 20%～80% of the liquid level height.
- The pipeline between the vacuum desorption tank and the absorption tower must be designed with sufficient slope to ensure gravity flow of the oil.
8.3 Absorber Tower Packing Maintenance
The packing inside the absorber tower is a critical component. After prolonged use, scaling and clogging may occur. Regular inspection, cleaning, or replacement is recommended. When tray efficiency decreases, the actual operating effect of the theoretical tray number needs to be checked.
IX Maintenance and Care
9.1 Routine Maintenance Items
|
Maintenance Items |
Cycle |
Operating Procedures |
|
Operating Parameter Check |
Daily |
Observe the absorption tower temperature, pressure, liquid level, and discharge concentration. |
|
Absorbent Circulation Pump Check |
Weekly |
Check the pump's operating sound, vibration, and sealing condition. |
|
Equipment Visual Inspection |
Weekly |
Check for leaks, abnormal vibrations, and unusual noises. |
|
Vacuum Pump Inspection |
Monthly |
Check the oil level, operating sound, and vacuum level to ensure they meet the standard (≤13.3 kPa). |
9.2 Regular maintenance
|
Maintenance Items |
Cycle |
Notes |
|
Emission Concentration Testing |
Quarterly |
Detect NMHC concentration at the emission outlet, ensuring it is ≤25g/m³. |
|
Absorbent Performance Inspection |
Every 3-6 months |
Check absorbent saturation and replacement. |
|
Absorber Tower Packing Inspection |
Every 6 months |
Check for blockages and cleaning. |
|
System Tightness Testing |
Yearly |
Perform procedures according to GB20952 requirements. |
|
Vacuum Pump Maintenance |
Yearly |
Replace vacuum pump oil and inspect seals. |
|
Absorbent Replenishment/Replacement |
Depending on usage |
Absorbent consumption is high and requires continuous replenishment. |
|
PLC Control System Calibration |
Yearly |
Check sensor accuracy and linkage protection functions. |
X Comparison of absorption method with other processes
|
Processes |
Recovery rate |
Emission concentration |
Investment Costs: |
Operating Costs: |
Scope of Application |
|
Pure absorption method |
Approximately 80% |
higher |
Low |
Medium |
Pretreatment/Large Volume Operating Conditions |
|
Condensation method |
≥95% |
≤25g/m³ |
High |
High Energy Consumption in Cryogenic Section |
High Concentration Vapor , Intermittent Operating Conditions |
|
Adsorption method |
≥95% |
≤10-25g/m³ |
Medium |
Medium (Activated Carbon Replacement) |
Low Concentration Deep Purification |
|
Absorption + adsorption combination |
≥95% |
≤25g/m³ |
Medium |
Low |
Mainstream Solution for Oil Depot Loading, Large Volume Operating Conditions |
|
Absorption + membrane + adsorption |
≥99.9% |
≤60 mg/m³ |
High |
Low |
High Standard Requirements (Grade A Enterprises) |
|
Condensation + adsorption |
≥98% |
≤20g/m³ |
High |
Medium |
Gas Stations, Small and Medium-Sized Oil Depots |
XI. Ordering Information
|
Project |
Contents |
|
Product Name |
Absorption-based tertiary Vapor recovery unit |
|
Product Type |
SDYD-1000 / YD-1000 / QKHB-YY |
|
Processing Capacity |
30-10000 Nm³/h (customizable) |
|
Production Cycle |
30-60 days (depending on throughput) |
|
Warranty Period |
12 months (from the date of acceptance) |
|
Equipment Design Life |
≥15 years |
|
Optional Configurations |
Online monitoring system, remote data transmission module, explosion-proof/standard type, PLC touch screen control |
|
After-Sales Service |
Technical support, on-site response within 48 hours |
The specific price and delivery time are subject to the actual inquiry.
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