*As published in Solids Processing NL October 2016 magazine**
PPG invested millions of Euros toward a very complex conveying project in one of its silica plants. The plant is responsible for the production of Agilon®, the innovative raw material used to manufacture car tires of the future. This project was especially impressive because the new pneumatic conveying system was simultaneously engineered and constructed in just one and a half years, while production continued as usual in the plant.
PPG Industries Chemicals is a pilot plant division of PPG Specialty Coatings and Materials International Group. While the company globally employs
PPG prides itself on innovative solutions, including pneumatic conveying
as many as 47,000 workers, this silica plant is relatively small with only 75 full time employees. Albeit its size, the factory is PPG’s only silica production site in Europe.
Silica has numerous applications in the industrial rubber industry – especially tires. In tires, silica is used as a filler to reduce wear, present less rolling resistance, and provide better road grip than its alternative, carbon black.
The newly patented Agilon product has been in development for less than ten years. Jos Hudepohl, project manager of PPG, explains,
“Agilon is modified silica in which we have already taken care of the additives introduced during the liquid phase. This relieves customers of emission problems in the production phase, and allows them to do more with the existing mixing capacity. With this new formula, the properties of silica have been enhanced 10 percent, which reduces the process complexity.”
Agilon® production process
The first phase of the production process is to create liquid glass from a solid form. This is done using special furnaces that allow the glass to dissolve using steam. The liquid mass collects in appropriate concentrations in a reactor vessel, along with certain levels of sulphuric acid, in order to generate a precipitation reaction. The remaining sediment is pure silicon oxide (SiO2). Any remaining liquids are then evaporated from the slurry using a spray dryer. This creates a rapid-flowing powdered product that is moved to stock silos before entering bulk loading stations for pneumatic conveying into big or small bulk bags. The Agilon production process has an entirely separate wastewater flow containing ethanol. The advantage of this clever, innovative sewage solution is that ethanol improves the purification process.
Four parties cooperated closely. Namely:
- Tebodin B.V.: Partner for the construction engineering and supervision.
- PMF Mechanical: Partner for the piping installation.
- Verwater Group B.V.: Partner for the electrical, instrumentation and automation implementation.
- Aannemersbedrijf Lamein B.V.: Lead construction contractor.
PPG project manager Jos Hudepohl explains the power of this consortium: “The planning of one and a half years’ development and construction was particularly tight. Engineering often took place on the spot during the project’s execution. The deadlines were very short and all parties were seated at the table every day.”
PPG is very satisfied with Tebodin’s input. Hudepohl says, “Their plan of approach was more convincing than that of other providers. When coordinating the entire project, Tebodin had a great advantage in that the suppliers all had relevant disciplines in common. For instance, the knowledge of engineering, dry bulk handling, chemistry, process engineering and utilities.”
Hudepohl explained that PPG opted for these parties because they gave the company confidence in achieving the plans of this contract. “Our goal has been reached and everything complied with our expectations. We are very satisfied with the results,” he said.
Apart from the pneumatic conveying system, PPG also invested in a tank storage for new chemicals, a loading bay for bulk trailers, silos for storage of raw materials and finished goods, reactors, a spray dryer, and a packing line for big bags. Dozens of vendors supplied products and services.
Besides the production plant expansion, PPG’s investment led to an adjustment from one to two production lines in the existing plant, which was a major challenge. Developed in cooperation with LeBlansch Bulk Handling Equipment BV, engineer Jaap Schoonhoven, outsourced by Stevens Engineering, designed an ingenious and compact new automated multiport unit. LeBlansch Bulk Handling Equipment BV played a dominant role as the supplier of Vortex diverter valves, multiport diverters, and necessary valve piping for the pneumatic conveying of powders.
“We are talking about four times the original capacity for six different powder flow options being handled,” Schoonhoven says. “Manual actions are now a thing of the past. The bespoke and high-quality diverter valves made a fully automated powder transport possible in place of manual switching stations. To give you an idea: This new system saves 21,000 actions a year.”
To support the new, innovative pneumatic conveying system, more than 2km (6,560 ft) of sophisticated pipework and exchange stations were installed in a relatively small area. The many hoses, valves and tubes in radius bends have been replaced by a compact design.
Schoonhoven says, “I did a test run with special valves and tubes from LeBlansch Bulk Handling a few years ago. We have taken everything apart after two years and couldn’t find any wear and tear. Therefore, we selected Vortex as the supplier for this large scale project.”
Hudepohl adds, “They also helped tremendously when weighing the benefits between installing one or two multiports. In this instance, they really looked at it from the user’s side, and PPG’s interests were the leading factor. In addition, LeBlansch Bulk Handling Equipment BV not only supplied fast, but the parts were also of high quality.”
Another reason for the system reconfiguration was that in manual operations, hoses may come off suddenly, creating a dangerous situation for employees who have to walk on top of hoppers or on uneven surfaces to connect hoses. “My main drive was to achieve maximum safety,” Hudepohl shares.
The co-planning with LeBlansch Bulk Handling Equipment BV garnered much appreciation from PPG. Hudepohl says, “LeBlansch Bulk Handling Equipment BV was in constant communication, and asked carefully what we had in mind.”
Designing in 3D scans
Koen Froeling, mechanical engineer at Tebodin, further developed the multiport’s design to use a 3D scan, which meant increased efficiency. Engineers scanned the existing floor plan in its entirety. The scan resolution, called a point cloud, was extremely accurate. Tebodin converted this scan into a 3D engineering package and the new expansion was engineered in this. The advantage of 3D scanning is that nothing is overlooked, so you no longer encounter anything unexpected – such as piping that’s in the way, for example.
Hudepohl shares, “This is how we realised we had to move the large multiport because of the position of the spray dryer’s burner box. Without the scan, we would not have found this issue until the multiport was to be installed.”
Froeling explains, “You actually design in a picture of reality, rather than via a drawing. The scan is used as a background in your tooling.”
Assembling the Multiport
To prevent errors during construction, the engineers allocated different colors to the pipes in the multiport’s design. As part of the expansion, a second multiport which has two lines in and seven lines out was installed. Together, the two multiports have 38 different product flows, in which the system blows each pipe clean before and after a batch. The curves of the tubes and the high-quality metals sourced to construct the tubes are designed so that wear on the metal is minimal. In addition to the space saved from the multiport configurations, it also simplifies maintenance. The service technician has easy access throughout the conveying system and hardly needs to work at high altitudes.
Froeling explains, “The large radius curves and tight spaces were complex to design. In partnership with PMF, we had a good look to see which pipes we could replace and when, in order to allow the existing process to continue as much as possible. Through good planning and preparation, we were often able to quickly and safely fit a valve into the system, and the manufacturing process could continue as usual.”
He continues with a summary of the engineering process: “The customer posed a question, which we then analyzed using a process flow diagram (PFD). This diagram was accompanied by mutual consultation with the customer to discuss the system’s many possibilities. Then, we created a process instrument diagram (PID) to explain the system’s routing. We discovered some unexpected challenges on-site during the project’s execution, for which we made adjustments. Continuous communication with all involved parties was very important. This complex undertaking with interim expansion became an extraordinarily challenging project.”
In the new multiport station, a major change was that switching takes place behind the panel now instead of in the factory. The software was quickly implemented so that the new multiport system could be switched over from one day to the next with minimal production loss. A safeguard was simultaneously built in to protect the system’s operations. “For example, the system checks whether there is another product on the relevant route,” Hudepohl says.
The speed of software implementation was characteristic for the rest of the project too. Froeling explains, “Given the late go-ahead for the expansion during the replacement project, we designed and built the second multiport in less than six months. The entire concept had to be reconsidered, as it were, but with two kilometers extra piping.”
“The conclusion of this impressive project is that we have a fairly small and unknown company in Delfzijl, but we are capable of exceptional performance,” shares Hudepohl. “Even for PPG as a whole, this was one of our largest projects ever, and we can be quite proud of it.”
Hudepohl explains that new valves built into multiport units not only ensure transition to a fully automated process, but also for a very efficient use of available space. For the Delfzijl plant, this project has led to a capacity growth of 30 percent. “The advantage is that we can transport both silica and Agilon via the new lines,” he says. “The production capacity is 100 percent utilized and the Agilon share will continue to rise. Expectations are high, given the increasing demand for Green Label tires.”