Tanker Oil Unloading Measurement

The ZHYQ-Ⅱ-XM Crude Oil Automatic Sampler complies with the national standard GB/T27867, international standard ISO 3171, and API 8.2 of the American Petroleum Institute. It effectively addresses three major challenges in automatic sampling during tanker oil unloading:

● Efficient handling of ultra-wide oil unloading flow range (typical value 30:1)

● Efficient response to large single oil unloading volumes

● Effective resistance to sea wind corrosion

The ZHYQ-Ⅱ-XM automatic sampling device is also suitable for automatic sampling of intermittent oil transfers on offshore platforms.

I. Equipment Composition

The sampling device consists of three major parts: the oil unloading main pipeline jet mixing system, automatic sampling system, and sample mixing and splitting system (optional).

1. Oil Unloading Main Pipeline Jet Mixing System

Any sampling equipment should collect as representative a fluid as possible. To ensure accuracy, the fluid received by the equipment must represent the most representative part of the entire pipeline cross-section.

When the fluid is uneven or multiple fluids are mixed, it should be mixed. Common mixing methods are dynamic mixing and static mixing. Given the adverse consequences of using static mixers (unsatisfactory mixing at low flow rates and significant pressure loss at high flow rates) during the ultra-wide oil unloading flow range (typical value 30:1) in tankers, static mixing is not recommended for tanker oil unloading. When designing a dynamic mixing system, the mixing requirements of C1/C2 listed in ISO 3171 must be met, requiring rigorous calculation.

1.1. Jet Mixing System

The jet mixing system consists of a jet nozzle assembly, sampling probe, and jet pump.

The material of the jet nozzle assembly is selected to match the material of the oil pipeline. The jet nozzle and pipe section flange are welded in the factory. The number, diameter, and fixed position of the jet nozzles, as well as the displacement and lift of the jet pump, are calculated using specialized SH software to ensure that the C1/C2 water dispersion ratio in the oil meets the standard requirements under the worst conditions (minimum viscosity, minimum density, and minimum oil flow). The jet pump is a high-quality explosion-proof centrifugal pump.

During the operation of jet mixing system, a small portion of the process fluid is extracted and sprayed at high speed upstream of the sampling probe, generating maximum energy injection in the pipeline and ensuring proper dispersion and uniform distribution of various flow phases across the entire cross-section, achieving rapid and efficient mixing with minimal pipeline pressure reduction. The sampling probe collects samples from the fully mixed liquid flow, ensuring the representativeness of the samples.

The mixing system provides crucial continuous mixing energy at low flow rates. If the natural turbulence is sufficient, the mixing system automatically shuts down.

1.2. Sampling Probe

The sampling probe can be fixed or retractable. If a retractable sampling probe is selected, sufficient space must be reserved for movement. The installation position of the sampling probe on the main oil pipeline must meet standard requirements.

2. Automatic Sampling System

The automatic sampling system consists of a skid-mounted cabinet, flow detection switch (flowmeter), online water content transmitter (optional), separator, portable pressure-resistant sample storage container, weighing system, explosion-proof control box, etc.

2.1. Online Water Content Transmitter (Optional)

Capacitance method

Resolution: 0.01

        Repeatability error: 0.05.

2.2．Portable Pressure-Resistant Sample Storage Container

The sample storage container has a large quick-release opening for easy cleaning and a smooth inner surface to minimize surface adhesion. Made of stainless steel, it includes a built-in jet homogenizing component, pressure relief device, and quick-connect fittings. Available in 5-liter, 10-liter, and 20-liter designs, with a pressure rating of 0.3 MPa.The standard configuration includes one container in use and one as a backup.

2.3. Separator

The separator extracts the required sub-samples and delivers them to the sample container. The minimum sub-sample volume is 1.0 ml, with a standard adjustable volume range from 1.0 ml to 10 ml.

The through-type separator directly discharges unit samples into the sample receiver, minimizing cross-contamination between batches.

The separator is electrically operated, with a maximum sampling frequency of 30 times per minute.

2.4. Flowmeter (Optional)

A flowmeter is installed in the sampling circuit to regulate and display the flow rate within the sampling circuit, ensuring sufficient flow to maintain sample representativeness and sample homogenization within the system.

2.5 Controller

The controller is based on Siemens PLC, and the human-machine interface uses a 7-inch color display explosion-proof touch screen. Digital parameter settings, equipment operation status display, and fault alarm message display. Equipped with RS485 communication interface and MODEBUS RTU communication protocol.

3. Sample Mixing and Splitting System

Connected via special pipes and a circulating pump, this system forms a mobile laboratory mixing and splitting device. The mixed sample is extracted from the bottom of the storage container, passed through a six-unit static mixer, and then discharged back into the storage container through jet piping. The deflected jet holes in the jet piping create jets when liquid is forced through the small orifices, causing the sample to rotate in the container. Power supply: 380V/0.5KW, equipment weight: 40Kg.

Dimensions (mm): L*W*H = 600*500*300

Mixing time generally ranges from 5 to 20 minutes depending on the sample volume and oil type.

II. Equipment Functions and Technical Parameters

1. Equipment Functions

1.1. Simplified Workflow Diagram

1.2. Functions

● The jet mixing system ensures that the C2/C1 water content ratio meets the requirements of ISO 3171, API 8.2, and GB/T-27867 at minimum oil flow rates, while additional pipeline pressure loss at maximum oil flow rates is negligible.

● Collection of flow-proportional samples ensures that the sampling rate is proportional to the oil transfer rate.

● Weight alarm: If the sample volume exceeds the limit due to unexpected situations, the weighing device automatically stops the equipment sampling operation and issues an alarm.

● Equipped with a rotor flowmeter with a measurement accuracy of 2.0, it regulates and displays the flow rate within the sampling circuit.

● Comes with an online crude oil water content transmitter, based on capacitance method, with a resolution of 0.01 and a repeatability error of 0.05.

● Equipped with an electrical heating system in the cabinet.

● Sample mixing and splitting: In the laboratory, the sample is mixed using the sample mixing and splitting system equipped with a circulating pump. After meeting the mixing requirements, samples can be mixed and split simultaneously until the required number of samples is obtained.

● 7-inch color explosion-proof touch screen with digital parameter settings and display.

● RS485 communication interface, MODEBUS RTU communication protocol.

● Detailed data transfer

1).   Data uploaded from the sampling cabinet to the DCS system:

① Equipment operating status

② Equipment fault messages

③ Sampling parameter settings

④ Real-time water content values

⑤ Real-time sub-sample count

⑥ Real-time sample weight

2).   Data collected from the DCS system by the sampling cabinet:

① Instantaneous oil transfer flow rate

② Instantaneous oil transfer temperature

③ Instantaneous oil transfer density

④ Water content calibration correction parameters

⑤ Set sampling operation parameters

3).   See Appendix Communication Data Table for details.

2. Technical Parameters

2.1. Sampling Performance Coefficient (PF): 1±0.1

Unit Sample Volume Coefficient (GF): 1±0.05

Unit Sample Count Coefficient (CF): 1±0.01

2.2. Sub-sample volume adjustable from 1.0 to 10 ml. Sampling interval 2-900 seconds.

2.3. Portable pressure-resistant sample storage container design volume: 5 liters, 10 liters, 20 liters.

2.4. Engineering pressure: 2.5-6.4 MPa.

2.5. Electrical explosion-proof identification: dⅡBT4. Electrical protection level: IP65.

2.6. Power supply: 380V, power: 2-3KW (jet mixing device calculated separately).

2.7. Skid-mounted cabinet dimensions: 800*750*1300 (L*W*H).

Total weight: 350-950Kg.

2.8. Jet pump installation dimensions, weight, and power load are determined by final design.

III. Order Sheet