Optimized unloading of crude oil in cold weather conditions
Jan 1, 2012 12:00 PM
A WELL-KNOWN phenomenon at crude oil terminals in cold regions is that certain types of crude oil transported in railway tankcars can be too stiff to unload. Extremely cold winter weather can bring crude oil transloading operations virtually to a halt.
To help solve this problem, Neste Jacobs, headquartered in Porvoo, Finland, developed an unloading device called Ecoarm. This ready-to-use system can be operated as is or configured by combining top-unloading, bottom-unloading, or top-warming technologies to meet clients' needs.
Traditionally, oil transported by train is unloaded through valves underneath the tankcar. The tool used for this is a base unloading arm with a built-in heating system.
“But if bottom unloading is not possible, which quite often is the case in the Baltic region, the car must be unloaded from the manhole on top of the tank,” says Staffan Lindberg, account manager at Neste Jacobs. “But it is very time consuming and inefficient in the winter to warm the tank from the outside with, for example, hot steam.”
The good thing about Ecoarm is that the system heats the crude oil via the top manhole and from the inside out. Roughly speaking, the system consists of a pump nozzle equipped with a heating coil that has two extendable hot oil spray nozzles on both sides of it.
“First, the pump nozzle is heated and pressed into the stiff oil,” Lindberg says. “When it begins to thin out around the nozzle, the oil is pumped to a heat exchanger on the outside, from which hot oil is sent back into the spray nozzles.”
As the crude oil thins, beginning from the midsection of the tank, the nozzles begin to move sideways and upwards and gradually rise to the top of the tank. This way, all the crude oil will be efficiently warmed up and can be unloaded with much less difficulty.
The key benefit of Ecoarm is that unloading can be done with high volume flows in very cold weather. The equipment is hydraulically operated and steered remotely, which makes it safe to operate.
“Ecoarm is the market's most efficient and versatile unloading system for oil products that are difficult to handle,” says Lindberg. “The remote operation of the unit, combined with controlled collection of harmful gases, makes for a safe working environment for operators. The system also operates well below flashpoint and possible volatile organic compounds can easily be collected.”
Lindberg explains that Ecoarm is often sold together with traditional base unloading systems. “But if the bottom valve is broken, our Ecoarm is an efficient solution for warming up the oil and making it possible to unload in cold weather.”
Due to a European Union directive that requires special valve arrays on the bottom of tankcars transporting oil, older tankcars with traditional valves cannot be used in EU countries. “The problem is that the traditional base unloading equipment with built-in warmers doesn't fit if the tank has EU-adapted bottom valves,” says Lindberg.
To address this problem, Neste Jacobs has recently developed a lighter version of Ecoarm with no pump. “Unloading is done by
gravity through the valves at the bottom of the tank,”
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