To obtain high-quality products from crude oil, complex processing processes are necessary. A vital factor is steam. For the Ruhr Oel refinery in the northern Ruhr area, STEAG has developed an environmentally friendly steam generation system that can serve as a model for other refinery sites.
Anyone driving past the site of the internationally operating petroleum company BP knows the scenario: an impressive number of huge storage tanks, miles of pipelines and tall chimneys. Here, STEAG is currently building an innovative energy generation system for the part of the refinery located in the Gelsenkirchen district of Scholven with the aim of significantly reducing environmental emissions and achieving greater efficiency in plant operation.
Over the next ten years, the BP subsidiary plans to invest around two billion euros in environmentally compatible modernization projects. One of the central investment measures is the “Steam and Power” project. STEAG was appointed as EPC contractor for the steam section. “Our aim is to secure jobs in the long term through safe and environmentally compatible action and high profitability. The investment in a modern steam supply system is an important step in this direction,” says refinery manager José Luis García Galera
„It is our concern to secure jobs in the long term through safe and environmentally compatible action and high profitability.“
José Luis García Galera, Refinery Manager
The main fuel used for steam generation is the refinery gas produced at the site. This energy recovery can reduce the number of flares required for safety – for example during start-up and shut-down activities of refinery production facilities. At the same time, the new energy-efficient steam boilers replace the steam supply from the neighboring hard coal fired power plant, which has been in place for decades. Another advantage of the STEAG concept is the significant reduction of emissions.
The core element of the future steam supply at the Scholven site will be four of the latest, state of the art steam boilers, which will be erected on the refinery site. The energy system developed by STEAG provides for heating of the boilers manufactured by Duisburg-based Standardkessel Baumgarte GmbH with the refinery gas produced at site. This energy recovery can reduce the number of flares required for safety – for example in the start-up and shut-down activities of refinery production facilities. This means fewer emissions. At the same time, the new energy-efficient steam boilers replace the existing steam supply system, which has been in operation for decades, with an adjacent coal-fired power plant.
„For the project, we have integrated expertise from different fields throughout the company.“
Volker Veelmann, Project Manager
At STEAG, Volker Veelmann is responsible for this trend-setting project. “With a project volume in the hundreds of million euros, the order is of great importance to our company,” says the former manager of the STEAG power plant in Bergkamen. The experienced engineer is currently in charge of coordination: “For the project, we have integrated expertise from different fields throughout the company and can now be very proud of this joint achievement.”
Rüdiger Völkner as site manager and Christian Hensel as technical manager are two of Volker Veelmann’s most important supporters in the “Steam” project. At the moment, it is the turn of process engineer Völkner: “From excavating the pits for the foundations up to commissioning, we expect a construction period of around two years.” Most recently, the construction sections were prepared using the vibratory tamping method. Columns are rammed into the ground to compact it so that it can support the steam boilers, which weigh several hundred tons.
These steam boilers produce the process steam for the refinery systems, with which the crude oil consisting of hydrocarbons is heated to such an extent that a certain component becomes gaseous and can thus be separated from the solid constituents. This produces gasoline and diesel oil, among other things. The steam is not only used for heating, but also as process steam in the operation of the entire plant, for example in the running of pumps.
Christian Hensel is responsible for this part: “Each of the two boilers in the northern part of the refinery will generate 140 metric tons of steam per hour at a pressure of 145 bar. In the two boilers in the middle section, there will be 120 metric tons of steam per hour each, at a pressure of 107 bar,” the technical manager explains. “And the 15 MW condensing turbine installed in the central section uses the process steam not otherwise required to generate electrical power from surplus refinery gas, and that power is intended for the refinery’s own requirements.
For safety reasons, redundant installations are planned in both parts of the plant: “One steam boiler at each location would suffice. Should that fail, the system would still be fully operational thanks to the second boilers. This so-called (n-l) concept ensures in all cases that all the gases produced can be used to generate steam, and therefore there is as little need as possible for flaring,” says the STEAG engineer.
The systems are to be handed over to BP in autumn 2021. By then, Volker Veelmann and his team will have thoroughly tested the concept for practical suitability and safety. For although the planning was established individually for BP’s Scholven site, the basic concept has far more potential: “With increasing environmental awareness, the requirements at refineries will also become more stringent,” says Volker Veelmann. “And with the concept implemented here, STEAG offers refinery operators an opportunity to meet future demands in terms of emissions and efficiency. That’s why we see this as a reference project for the future.”
In the refinery process, desalinated crude oil is first heated to around 400 degrees Celsius in a tube furnace and then fed into the lower part of a very tall rectification column. Steam (process steam), which drives the evaporation of the crude oil, is fed into this column at high pressure. The column contains several compartments separated by horizontal walls. Overflow openings allow lighter fractions to flow into the higher compartments, and an outlet serves to discharge liquid products from each compartment. Out of these compartments flow the substances that are the basis for fuels such as gasoline and diesel oil.