Researchers from Tomsk Polytechnic University and South Kazakhstan University have proven that even old oil treatment plants can be done much more efficiently. They analyzed the operation of a real plant with a capacity of 4 million tons per year and found a way to radically reduce fuel costs. The result is impressive: heat consumption fell from 178 to 41 megawatts without loss of product quality.
At any field, oil must first be prepared for transportation. Gas, water and salts are removed from it. To do this, raw materials are heated in furnaces, burning associated gas. Typically, in such installations, a huge amount of heat simply flies out into the chimney. Flue gases escape at temperatures above 300 degrees, and the heated streams of oil and water are wasted.
Scientists used the pinch analysis method. This is an engineering approach that allows you to build an ideal heat exchange scheme between different flows inside the plant. First, specialists collected accurate data: temperature, flow rate and heat capacity of all flows. It turned out that commercial oil, when cooled from 46 to 10 degrees, carries more than 5 megawatts of thermal power. Produced water adds another 9 megawatts, and flue gases add almost 0.2 megawatts. At the same time, inlet crude oil requires nearly 15.5 megawatts of heating, and burner air requires another 0.9 megawatts.
The mathematical model showed that within one plant it is possible to return over 12 megawatts of heat to the process, which was previously simply lost. Engineers rebuilt the heat exchanger circuit so that hot flows heat cold ones directly. Ovens and refrigerators now turn on only when internal resources are low.
As a result, the need for external heating fell by 77%. The main energy for oil preparation does not come from gas burning, but the heat that previously escaped into the atmosphere.
We separately calculated the economy. To bring the scheme to life, about 8 thousand square meters of new heat exchangers will be required. Capital costs were estimated at $4.4 million. At the same time, annual fuel savings will reach $2.7 million. Even taking into account expensive loans, the project will pay off in three and a half years. The internal rate of return exceeds 60% – this is an excellent indicator for industrial energy.
Engineers further simplified the design by removing two low-power heat exchangers. Their contribution to savings turned out to be meager, and the cost was comparable to full-fledged units. After this, capital costs became even lower, and financial attractiveness increased.
The technology is ready for implementation at any similar installations. It does not require complex reconstruction and pays off faster than replacing furnaces or building new facilities. For oil workers, this is a way to dramatically reduce the cost of preparing raw materials and reduce emissions into the atmosphere.
Source: Global Energy
Image: Global Energy
