Why Radar Technology for Tank Gauging

“Safety is more important than cost. We can now perform real-time monitoring of the floating roofs from the control room.” Vice General Manager, ZPG

Many terminals and tank farms struggle because they use outdated equipment resulting in unreliable operations, inefficient routines, and high operational costs.

Emerson’s three generations of Tank Gauging Technology

Rosemount 5900S Radar Gauge

Figure 1: A Rosemount 5900S Radar Gauge Installed on Tank

The Rosemount Tank Gauging System has been developed and perfected with the best-in-class Radar technology over decades.

Radar technologies offer various benefits:

  1. Non-contact, No moving parts, and No maintenance
  2. High reliability, High accuracy
  3. Long life
  4. Lowest Cost of Ownership and Fastest Return on Investment

Tank Gauging Applications – Mechanical Gauge Challenges

Figure 2: Complex interiors of the Mechanical Gauge demonstrating the challenges of maintaining spare parts, calibrating the device and upkeep.

Mechanical gauges have intrinsic drawbacks including moving parts such as
displacer, wire, wire drum, weighing mechanism, electric motor, and encoders. In the case of tank gauging instruments, tape is used to measure ullage or innage which requires instrument contact with the liquid while measuring. Having instruments in contact with the product is not desirable due to reliability, contamination, and safety concerns among other risks.

In the case of Servo technology, a weighing system in the servo gauge senses the tension in the wire, signals from the weighing mechanism control an electric motor in the servo unit and make the displacer follow the liquid level movements. For these instruments, constant wear and tear due to movement remains an issue. Customers spend a lot of time and effort on regular maintenance / cleaning, stocking spare parts, engaging in service contracts and frequently calibrating or recalibrating the instruments.

Radar based Tank Gauging is a better Choice

Density Measurement

3051S Pressure Transmitter & 2240S Multi-input Temperature Transmitter

Figure 3 (left): 3051S Pressure Transmitter used for precise online density measurement for Tank Gauging Systems; (right): Rosemount 2240S Multi-input Temperature Transmitter for Tank Gauging Systems

Density is an integral part of providing feedback on the composition of the liquid inside the tank.

Using Mechanical devices such as servo for measuring density is not supported by any engineering standards. Also, installed accuracy is too low, there is no level reading when instrument is measuring density and there is no online measurement.

For Rosemount Tank Gauging, the best practice is to use a high accuracy pressure instrument to measure vapor and liquid pressure (density). This is suitable for most applications including crude oil tanks and floating roof tanks which is compliant with the standardized method outlined in API MPMS 3. 6—Manual of Petroleum Measurement Standards Chapter 3-Tank Gauging Section 6-Measurement of Liquid Hydrocarbons by Hybrid Tank Measurement Systems.

Water Level Measurement

Automatic measurement of the free water at the bottom of the tank may be required for accurate inventory assessment.

Mechanical devices like Servo share several drawbacks such as online measurement is not available while measuring, contamination on the drum and displacer mechanism during the dipping process and the need for special displacers which requires additional maintenance.

In Rosemount Tank Gauging Systems, the Rosemount 2240S Multi-input Temperature Transmitter can connect to sixteen 3- or 4-wire temperature spot elements and an integrated water level sensor made with cutting edge capacitance technology. With features like on-tank push-button calibration and an active length of up to 1000mm, it is the perfect solution for bottom water level measurement needed for inventory assessment.

Radar Tank Gauging ROI

Why invest millions of dollars in old technology?

Figure 4: Reduced Uncertainty comparison between Radars and Some Outmoded Technologies

Going for radars lead to both upfront and ongoing cost savings. Upfront significant CAPEX savings on fixed roof tanks are accrued because there is no stilling well required on these types of tanks. Other benefits include better reliability and availability as fewer personnel need to climb the tank, reduced the risk of tank overfill and better safety.

Non-contacting radars have fewer moving parts and reduces measurement uncertainty which enables higher profit. ROI from the Rosemount Tank Gauging System always helps our customers justify a return on investment quicker compared to outmoded technologies.

Interested to learn more on this subject? Join us at Emerson Exchange Asia Pacific, coming on October 26-28, 2021. Register for the event via Emerson Exchange Asia Pacific.

Oct 26-28 Emerson Exchange Asia Pacific

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