What is the Difference Between VDU (Vacuum Distillation Unit) and CDU (Crude Distillation Unit)?

Vacuum Distillation Units (VDU) and Crude Distillation Units (CDU) are two essential technologies in oil refineries, each serving distinct purposes and operating under different conditions. Understanding their differences is crucial for optimizing the processing of crude oil and its residuals.

DOING waste oil distillation machine

Processing Material

CDU: CDU primarily process raw crude oil directly from production fields. In the context of waste oil distillation, CDU technology serves as the foundational method. It can refine various types of waste oils, such as waste lubricants, waste engine oil, and pyrolysis oil, into non-standard diesel. The diesel can be used as feedstocks for further processing or as final products.

Processing materials of CDU

VDU: VDU process the atmospheric residue, which is the heaviest fraction obtained from the CDU. Using advanced vacuum distillation techniques, VDUs further refine these residues into even lighter and more valuable products, such as light and heavy vacuum gas oils (VGOs). These VGOs can be used as feedstocks for other refining processes such as hydrocracking or catalytic cracking, maximizing the value of the waste oil.

Temperature

CDU: CDU require higher temperatures to vaporize and separate lighter fractions from waste oil. The temperature in the distillation reactor increases from top to bottom, typically ranging from 250°C to 400°C, to match the increasing boiling points of the hydrocarbons. This high-temperature operation is necessary to ensure the efficient separation of lighter hydrocarbons.

DOING CDU distillation reactor

VDU: VDU operate at lower temperatures compared to CDU due to the reduced pressure. The operating temperature range is typically between 350°C and 450°C. The lower temperature helps in avoiding thermal cracking of heavy hydrocarbons, which could lead to the formation of undesirable by-products and reduce the overall efficiency of the process.

Operating Pressure

CDU: Crude Distillation Units operate at atmospheric pressure or slightly above it, typically ranging from 1 to 1.5 atmospheres. This is the first major processing unit in an oil refinery, where waste oil is heated and separated into different fractions based on their boiling points. The atmospheric pressure allows for the initial separation of lighter hydrocarbons without the need for complex pressure control systems.

VDU: Vacuum Distillation Units, on the other hand, operate under vacuum conditions, significantly reducing the pressure inside the distillation column to around 10 to 40 mmHg (millimeters of mercury). This low-pressure environment enables the separation of heavier fractions at lower temperatures than would be possible at atmospheric pressure, preventing thermal degradation and preserving the quality of the products.

Products

CDU: CDU produce a range of products, including non-standard diesel, and asphalt. These products are essential for various applications, from fuel production to chemical feedstocks.

DOING CDU products

VDU: VDU focus on further refining the atmospheric residue into more valuable products such as light and heavy vacuum gas oils and vacuum residue. These products have diverse applications in downstream processing units, such as in the production of lubricants, waxes, and other specialty chemicals.

As a leading manufacturer of waste oil distillation machines, DOING Company utilizes CDU technology as the basis for our efficient and effective systems. Our waste oil distillation machines are designed to process used oils, converting them into valuable products such as diesel and asphalt. By incorporating advanced distillation techniques, we ensure that the processing is done efficiently, minimizing energy consumption and maximizing product quality.

DOING CDU manufacturer

DOING Company offers a range of services to our clients, including customized solutions tailored to specific waste oil processing needs, comprehensive technical support, and training programs to ensure optimal operation and maintenance of our equipment. We are committed to providing innovative solutions for waste oil processing, helping our clients turn waste into wealth.