Systems for WSR storage and dosing
The equipment for storing and dosing WSR is available for paper machines with performances of 1 to 100 tph. The resin storage concept depends on a PM capacity.
WSR deliveries in 1,000 kg intermediate bulk containers (IBCs) can be utilised for machines with capacities of up to 20 tph, 15 to 23 ton road tanker deliveries are suitable for higher PM performances. If the IBC source is utilised then the "mother-daughter" system configuration can be utilised meaning placing the containers one above another. The bottom work container volume is 1,200 litres to contain the entire volume of a standard 1,000 kg IBC. Both containers are placed in a steel frame, the top one from which WSR is flowing down by gravity to the work container is handled by means of a crane or a forklift. The bottom work container is equipped with a limit or an analogue 4-20 mA level sensor providing a signal of the container level status to the PM control system.
If the IBCs cannot be utilised due to a high consumption of WSR, PAPCEL offers to build one or more storage tanks. Their volumes are chosen with regard to the product logistics, usually 25 - 30 m3 to contain particular deliveries with a sufficient reserve capacity. It is suitable to design the storage tank system so that each WSR delivery is pumped from a tanker to a tank cleaned in advance while another tank is at the moment used as a source. Thus two or three tanks are simply operated in rotation and their cleanliness is need fully managed especially wherever high ambient temperatures are common.
The tanks are equipped with automated drawing system. The fittings enable operators to set a route and a tank from the control board in the operators' room while the control system arranges correct drawing the WSR delivery off to a corresponding tank. The WSR tank storage systems are usually designed for a fully automated operation mode. Therefore the tanks and fittings are equipped with common level sensors and transmitters of particular fittings' statuses
Dosing stations are designed from case to case. A dosing pump can work independently. For high-performance PMs spare pumps are installed to be switched on automatically or manually if work dosing pumps fail. Dosing stations usually work with throughputs of 10 to 1,500 lph but more powerful pumps can be used.
Pump types depend on a performance. Electric diaphragm pumps can be used for throughputs up to 375 lph while for performances of thousands litres per hour screw (Mohno) pumps are used. Dosing stations are usually designed as particular units in support frames. The frames are fixed in the specified positions by means of chemical anchors and connected to input/output pipelines, signal and power cables.
Before inputting the dosing point the product may be continuously proportionally diluted with raw or purified water. The dilution is fully automated and it is switched on at the moment when the pump is starting. A diluting water flow is controlled either with a manual valve (then the ratio is constant) or with an automatic control loop controlling the diluting water flow rate in an exact ratio against the WSR.
Materials: The system can be made from plastics (PP, PE) or from AISI 316 stainless steel. The tanks are either delivered mounted (standing on legs and anchored to concrete foundations by means of anchoring screws) or welded on site (and in such a case the tank bottom is embedded in concrete).
DSR dosing systems
PAPCEL offers various systems for preparing and dosing DSR, e. g. guar gum (galactomannan) or CMC (carboxymethycellulose) solutions.
The equipment covers a wide range of PM capacities from 1 up to 50 tph. Generally the equipment prepares a solution of a specified concentration from a powder product and then doses the solution to the PM system in an exact flow rate.
The power product is purchased either in 20 to 50 kg paper sacks or in large volume (650 to 1,000 kg) Big-Bags. The equipment consists of a standard 430 litres hopper containing hundreds kg of the product (depending on its specific weight). For a higher demand silos are used either for 1 to 10 m3 or for other volumes (similar to those used for deliveries and dosing starch) if the product is delivered in road tankers. The Big-Bag systems are delivered either together with appropriate lifting towers or suitable existing customer's devices can be utilised. The powder material is poured out to the hopper and from there it is delivered in defined mode to a dissolving batch by means of a screw conveyer. The screw conveyer drive is controlled by a frequency converter so that a high dosing accuracy is achieved. A quantity of the product delivered to the dissolving batch is measured by means of a strain-gauge weighing apparatus installed in the batch legs. The batch lid holds a high performance disperging agitator with a motor the input of which is designed depending on the dissolved material, its final concenration and viscosity. The agitator work element is a Z-disc. The agitator is driven directly or by a belt gear. Its motor is controlled by a frequency convertor thus increasing the system variability with regards to the operation conditions. The dissolving batches include systems of measuring water, high pressure walls and agitator sprinklers, systems of filtering air during pouring material and measuring and control (M&C) elements (sensors of level, temperature, on demand sensors of viscosity M&C). The solution is pumped out either with diaphragm pumps driven by pressurized air (with a high capacity and a long lifetime period) or with screw (Mohno) pumps either with controlled or with uncontrolled performance or with centrifugal pumps. The solution is pumped to a storage tank with a volume designed for the given conditions. The tank volumes are in a very wide range of 3 to 100 m3. The tanks are equipped with agitators to homogenise the solution, with level sensors and emergency level detectors. The dosing stations are designed for required performances of tens to thousand liters per hour. Electric diaphragm pumps or screw (Mohno) pumps are always driven with frequency convertors. The solution flow rate is measured either with inductive or for higher demands with mass flowmeters. The dosing stations are designed with regards to the performance and they include either one or more pumps with needful fittings and M&C elements. They are usually designed as compact units to be connected to input/output pipelines by means of standard flanges. Connections to signal and power cabling are solved as per the on-site situation. Switchboxes or switchboards can be used or the M&C elements are connected directly to the mill control systems.
Materials: The system can be made from plastics (PP, PE) or from AISI 314/316 stainless steel. The tanks are either delivered mounted (standing on legs and anchored to concrete foundations by means of anchoring screws) or welded on site (and in such a case the tank bottom is embedded in concrete).