Background
Sociedade de Angolana Betumes in Lobito is the only company in Angola (South West Africa) licensed by the Angolan Ministry of Oil for the import and sale of bitumen. There is a national programme for the immediate restoration of approx. 8000 kilometres of road and, in the long term, for the restoration of approx. 70000 km of road. Ships deliver the bitumen to the port of the loading station. It is then stored in a heated tank farm. The tankers are fi lled here and the bitumen is then transported to the road building sites. The capacity of the loading station is approximately 10000 tonnes per month.
• Storing the bitumen in a heated tank farm
• Automatic loading of tanker
• Low pump capacity
Measurement requirements
The level meters must be able to deliver reliable, accurate and highly repeatable measurements. Other requirements include simple installation, immediate operational availability without a complex start-up procedure and low maintenance. Furthermore, the operator needs display units to configure the device on site, i.e. measuring devices that can be read and operated at eye level to avoid climbing up the tank. In addition, all the measurement data must be directly transmitted to the control centre and the purchasing department to optimize warehouse and fuel management. Previously, the power plant had used a float-type level gauge system. However, these mechanical measuring devices have two major disadvantages:
1. Their accuracy depends on the product density. If the density changes, the results are inaccurate.
2. The considerable cost and effort associated with the installation and maintenance of such devices.
Measurement requirements
Bitumen is stored in a tank farm at approx. 150 °C. When loading into the tankers, the temperature must be approx. 135 °C for the bitumen to remain in liquid form. The tankers are partially thermally insulated and they transport the bitumen directly to the road building sites. The various parts of the system communicate with one another via a modbus interface.
Solution
For this application, KROHNE supplied four mass flowmeters with a single straight measuring tube: OPTIFLUX 7000 F, size T50. The devices are thermally insulated so the bitumen remains in liquid form. The four BM 110 batching masters that were also supplied control the metering of the bitumen automatically and independently. The loading station can fill up to four tankers at the same time. The mass flowmeters forward the data about the quantity filled directly to the batching master devices, which control the batch process. The batching masters must use a modbus interface to forward the dosing values to a printer multiplexer PCC 3008 in order to use the printer to document the quantity of bitumen filled.
Customer benefits
Since this version of mass flowmeter features a single straight measuring tube, only very minimal additional pressure loss occurs with the devices. That means that the loading station manages with minimal pump capacity when filling the tankers. The tankers are loaded at a flow rate of 42000 kg/h. The filling time is thus very short, cutting down substantially on costs. The reliability and accuracy of the KROHNE devices are what impressed the customers.
Products Used
OPTIMASS 7300
• Only mass flowmeter with a single straight measuring tube available in
Stainless Steel, Hastelloy®, Titanium and Tantalum
• Minimal pressure loss
• Reliable measurement of mass and volume flow, density, temperature,
concentration and solid content
Batching Master BM 110 i
• All information displayed for reliable and automatic filling
• Inputs and outputs for analogue and digital data transmission
• Modbus interface
• Flow control (mass or volume) during metering
