BVG Plant for the Preperation of Starch, Chemical Additives,
and Automatic Felt Cleaning


Propapier PM 1 assigned BVG Bauer-Verfahrens-technik-GmbH as the supplier for both their chemical processing and automatic felt cleaning plants. The order was given to BVG because BVG could offer the most innovative and economical concept for the handling of all their chemicals. In addition, references from wellknown paper manufacturers spoke highly of the effectiveness BVG displayed. The goal was to utilize as few chemical as possible and make it as inexpensive as possible. Special care was necessary, in order to keep contamination of the closed water circuit as low as possible. To a large extent BVG had a free hand in the pursuit of this goal. The order consisted of the selection of the chemicals, the complete engineering, the supply, assembly, start-up, and optimization of the plants. The emphasis was to guarantee a fully automated plant - without the need of local service personnel. The individual components are controlled and regulated by a Neles-Automation based PLC platform. For the Felt Cleaning, BVG supplied and installed a separate PLC/PC - based on the Siemens S7/WinCC platform.
Altogether, plants for nine different chemicals were provided, all of which were implemented strictly under the guidelines of the WHG. The plants at PM 1 pull together like a net. The chemicals are delivered in powder or liquid form and provided with storage over the unloading stations in tanks and silos. The materials are metered and transported from their addition points, through a BVG recipe manager, automatically.

The plants in detail:


Starch Plant

Only native starch is used, which is enzymatically converted "in-situ" with the BVG – Super - ECC. Over forty operational plants - world-wide - give references and praise, terming BVG as the market leader in this area.
Native starch can be delivered in either powder or slurry form. A silo with a volume of 250m³ is available for powdered starch. Two individual tanks, each with a volume of 250m³, are available for delivery in slurryform.
Since start-up the plant ran initially with powder commodity. Continuous slurry make down is produced directly within the framework of the silo. BVG uses their own developed concentration regulation, where a constant guaranteed concentration of +/-0.15%d.s. is achieved. The plants capacity goes up to 2.5 metric tons/h of native starch. The degradation takes place continuously in the BVG converter. Converted starch is stored in a 30m³ tank and pumped into a ring-circuit, to the two opti-sizers. There, the final concentration can be adjusted differently for both the top and bottom layers. The surface sizing of the production line can be improved by means of a synthetic surface-sizing additive. Additionally, the surface can be dyed. There are separate unloading stations, holding tanks, and metering stations for both surface-sizing additives and dye.

 

Starchsilo and Slurrytanks

Chemical Additves

The most important task within the wet end chemistry is to guarantee an optimal retention. That task is often difficult when mixed waste paper is used. At Propapier, two retention agents are used; aluminium sulfate for the micro flocculation and regulation of the pH value to 6.5, and Polyacrylamide (PAM) for the actual flake retention on the wire. Both products are delivered in solid form and prepared in special plants.


Aluminum-Sulfate

Al2(SO4)3 is delivered ín a size range of 8<x<40mm, by truck, and provided with storage in a 80m³ silo. The dilution station is located directly within the silo framework. A saturated solution is produced, which can then be further diluted. In this way, a solution with constant concentration can be produced by the simplest means. This solution is temporarily stored in a storage tank and metered out with a pump. The addition amount is regulated by the pH value.
Apart from the regulation of the pH value and formation of a micro flocculation, aluminium sulfate offers still another set of advantages, which the paper maker is pleased with.

Solvingplant for Aluminum-Sulfate

Polyacrylamide (PAM) Processing

With the application of PAM (Polyacrylamide), preference was given to powder commodity over that of liquid, for cost reasons. However, the purchase of powder commodity requires an additional powder-dissolving plant and a larger expenditure for handling. Since it is a product which can be difficult to dissolve, it is important that the dissolving-plant is well constructed and of sound design.
In the present case, the plant consists of a big-bag handling station, compressed air delivery, a special wetting section, a preparation tank, a storage tank, metering station, and a filter station at the addition point. Multiple finishing containers are not necessary. It is also a point to use only freshly prepared product.

PAM-Powder Solvingplant

Storage and Dosage of Anti-Foaming Agent

Anti-foaming agent is delivered likewise and provided with storage in a 15m³ silo. Anti-foaming agent is applied at seven metering points on the PM and in the Wet End. The metering of all chemical additives is centralized to the chemical-additives building by individual branch lines with the appropriate dilution. In this way, the factory is kept free of numerous containers. The metering pumps and metering quantities are registered and controlled through the PLS.

Dosingstations for Anti-Foaming

Automatic Felt Cleaning

To save on personnel and chemical costs, BVG would provided a complete ready to use automatic felt cleaning system. The BVG-Super-Clean, represents a new achieve-ment in design. The idea, which is appropriate in this case, consists of washing on the basis of concentrated hydrochloric acid and concentrated caustic soda solution, fully automatic, without the need of personnel, and as economical as possible. Other chemicals (i.e. on the basis of Tensides) are not needed with this plant. Since only in-organic materials are used, the closed-cycle profit- substantially from this. The plant is controlled and regulated by a separate PLS system based on the siemens S7, with WinCC as the HMI user interface.
The plant consists of two unloading stations for concentrated caustic soda solution and hydrochloric acid, storage tanks, dilution stations, service tanks for diluted caustic soda solution and hydrochloric acid, chemical exhaust trap, dosing pumps, and a spraying bar. The entire plant, the pumps, the containers, and all the piping are implemented in plastic material in order to avoid pitting corrosion from chloride. This plant will see a return of investment within six months of operation with the cost saving on chemicals and felt alone. The entire chemical concept worked very well under operating conditions. It did not have to be changed or critically improved in any way. It also turned out that the assigned technology, the requirements for production, became fully justifiable, particularly under the less favourable conditions of the closed water circulation system.

Felt Cleaning: Tanks for Acid and Caustic