Energy Efficiency How to Save Energy with Venturi Orifice Steam Traps
At Levaco Chemicals, process steam is the principal heating medium used in the reactors. To ensure that this valuable energy source is used as efficiently as possible, the company chose venturi orifice steam traps manufactured by EBE Engineering, Essen, Germany. Levaco’s plant engineer used the steam traps as a basis for comparing different steam trapping methods. His findings came as a surprise to the rest of the team.
Leverkusen/Germany — Levaco Chemicals has its headquarters and production facility in the Chempark Leverkusen, which is a major industry centre in this region of Germany. On this site Levaco produces various specialty chemicals such as dispersants, emulsifiers, wetting agents, defoamers and superabsorbents for numerous industries. Previously a part of the Bayer Group, the company, which now belongs to the Diersch & Schröder group, can look back on more than 50 years of experience in chemical production.
In order to be successful in the market, Levaco is constantly working to improve its efficiency. As part of these efforts, the company constantly optimizes its energy management by implementing industry best practices with the aim of identifying savings opportunities. Steam is one of the most effective factors to target as it is needed in considerable production volumes in the reactors. Steam energy is supplied by the chemical park operator Currenta. Savings in steam usage offer true bottom-line savings, reducing direct energy costs in production. Any steam losses, on the other hand, or a reduction in heat transfer efficiency lead to higher costs, poorer productivity in the reactors and higher energy requirements. This can be caused, for example, by poor efficiency in steam traps.
Tom Hummel has worked as a plant engineer at Levaco since 2014. He was looking for a suitable technical topic for his master’s thesis in industrial engineering at the University of Applied Sciences for Economics & Management (FOM), Essen. He decided to conduct a comparison between the Ecoflow venturi orifice steam traps from EBE Engineering, which had never previously been installed in the company, and conventional float steam traps. “As a member of our company’s energy management team, I constantly look for ways to save energy,” he says. “The steam trap comparison was an excellent project to balance the company’s objectives and my own.”
In total, 36 reactors are in operation on the site. Their capacities range from three to 25 cubic metres. One or two steam traps are installed per reactor, and a large number are also needed for the steam tracing systems. Altogether, more than 250 mechanical steam traps of various types (bimetallic, thermal, float) are installed in the steam system.
The venturi orifice steam trap project began by measuring the performance of the existing mechanical steam traps on one of the three largest reactors. For this, Tom Hummel began by identifying two products with a wide reference range. Both products were specifically chosen due to their different physical properties, in particular their viscosity. As a consequence the steam volumes required for the processes and the heating times were very different. This made it possible to investigate a larger operating range for the steam traps.
The reactor selected produces 27 different products with varying amounts of feedstock. The total annual tonnage of the 20-cubic-metre reactor is about 3,600 tonnes. The plant operated with a steam pressure of 30 bar and consumes about 200 tonnes per year. In autumn 2019, a planned maintenance shutdown was used to install two venturi orifice steam traps. As the chosen venturi steam traps comply with all European dimensional standards for valve installation, they were interchangeable with mechanical steam traps.
In his comparative analysis, Tom Hummel found that the Ecoflow venturi orifice traps used an average of 22.4 percent less steam in the process than conventional mechanical traps for the first product in the test. For the second product, the savings were 18.8 percent, confirming that for both products the use of the venturi orifice steam trap gave steam savings compared to mechanical float steam traps. This is due partly because venturi orifice steam traps do not have moving parts that can wear out, leading to greater steam consumption.
In fact, I expected the venturi steam trap to save steam beforehand. However, when I saw the actual measured values, I was surprised at the amount of steam saved.
Shorter Heating Times
During the analysis, the venturi orifice steam trap also showed a reduction in the reactor heating cycle time for the two products being investigated. Due to better steam energy utilisation, the processing speed could be increased and thus for batch operation the production volume could be increased. For the first product, an average time saving of about 27 min or 16.6 percent was observed, for the second product the average saving was about four minutes or 11.3 percent. According to Hummel, this could be due to how the venturi orifice steam traps handle start-up from cold. When the condensate is cold, the venturi trap is physically equivalent to a simple orifice. Compared to,say, a float trap, the cold condensate is discharged faster from the heating coil. Another reason could be that the continuous discharge of condensate through the venturi steam trap allows steam to be introduced into the process more quickly, compared to the intermittent operation of a float trap.
“As we produce many different products, different mass flows of condensate can occur,” explains Hummel. “In addition to the steam and time savings, the scale of the venturi orifice steam traps’ operating point is therefore also an advantage. This is because, due to the orifice and venturi operating range, it is possible to respond flexibly to any changes in the condensate mass flow that may arise during a product change.”
After these positive results, venturi orifice steam traps are to replace existing mechanical traps on an identical reactor. In the long term, Levaco plans to replace defective mechanical steam traps on the larger reactors with Ecoflow venturi orifice steam traps from the Essen-based manufacturer.