IN-DEPTH INTRODUCTION TO THE SANICIP™
POWDER RECOVERY
The GEA Niro Sanitary Bag Filters-SANICIP™ is designed for the application of dry filter entrapment and collection of particulate of products from exhaust air of spray dryers. The main applications are powder recovery from spray dryer exhaust systems for food, dairy and pharmaceutical products. As the entire system can be Cleaned-In-Place (CIP) between the product changes without changing the bags, the bag filter is also suitable for other related products.
LOW EMISSIONS AND LOW PRESSURE DROP
The unit exceeds every particulate emission requirement. Collection efficiencies are typically greater than 99.8%, with emission levels typically less than 10 mg/m3. Low-pressure drop across the bag filters mean long bag life, reduced energy consumption and noise emission.
DESIGN & CONSTRUCTION
Each bag filter selection is computer modelled against the specific application, for optimum cost effectiveness and performance. The model draws on an extensive database of live applications, which allows for a guaranteed performance.
Tangential inlet enhances separation of product in dust-laden air and reduces the particulate abrasion on filters. The cylindrical housing and the bottom cone construction means strength without stiffeners as compared to rectangular systems. Circular design eliminates dead corners and decreases the probability of material bridging.
Designed for optimum air-to-cloth ratio and powder load (due to one bag being blown at a time).
Cleaning by water, caustic and acid solutions with provision for self-draining of the fluid.
Fully automatic sequence control during production, CIP washing and drying of the unit after CIP.
Low Maintenance and short dry-out time compared to other washable sanitary bag filters.
Design Codes applied to the unit are in compliance with the 3-A/USDA (Pending) and EN 1672-2 sanitary standards.
A vast range of standardised design configurations (i.e. bag area range from 6.3 to 940 m2 and bag lengths range from 1.75 m to 6 m) increase the suitability to the building requirements and reduces the space requirements for new installation. The vast range of design configurations also facilitates the easy replacement of cyclones for retrofits without major change in the buildings.
Functional features:
The basic influential factors for the correct function are based on the following parameters:
- Type of powder, composition of the exhaust air and the particle size distribution.
- The plant and process for producing the powder.
- The degree of emission losses to the ambient surrounding and limitations.
FILTER BAGS CLEANING SYSTEM
The SANICIP™ cylindrical filter is equipped with a fully automatic bag cleaning system. The cleaning of the filter bags is achieved by impulsive scavenging through the reverse jet nozzles system positioned above the bags.
The nozzle ejects a burst of cleaning air down into the filter element at intervals adapted. The tension release occurring due to the air leaving the reverse jet nozzle produces a pressure wave that continues across the entire bag length. The exhaust airflow is turned into cleaning airflow, the bags are stretched and the adhering product is thrown away into the conical bottom chamber and discharged through the product outlet nozzle. The frequency and duration of the cleaning sequence can be adjusted to suit the actual running conditions.
REVERSE JET NOZZLE (PATENT PENDING)
Compressed air is blown into the bag through this specially designed and developed nozzle. A jet is formed which draw air from the clean side into the bag thus saving the compressed air. The nozzle is also used for the internal bag CIP.
BOTTOM CONE HEATING
In order to avoid condensation, warm air is led into the double wall duly equipped with baffles to ensure uniform heating of the total surface. A constant wall temperature is maintained during operation and standby conditions.
FLUIDISED BOTTOM (OPTIONAL)
The key purpose is to achieve a constant product flow from the bottom of the bag filter housing.
PNEUMATIC HAMMERS
In order to facilitate the release of any deposits, the bag filter bottom cone is equipped with pneumatic hammers.
CLEANING-IN-PLACE SYSTEM (CIP) (PATENTS / PATENTS PENDING)
The systems are designed to allow cleaning solutions to be circulated/passed through the unit and remove the material that has been deposited or has grown during production. No dismantling of the equipment is normally required with this system. Specific cleaning procedures are optimised for each particular application to ensure the reliability and repeatability of the cleaning process.
The Internal bag CIP cleans the bag from the inside towards the dirty side. Atomized clean water is injected into the inside of the bag through the reverse jet nozzle. Penetrated product in the bag material is forced out towards the dirty side and the used water is not re-circulated in this step. The reduced water consumption is achieved through the atomization. This feature is extremely important, as this is the only way to wet clean the bag against the entrained product.
The Outlet chamber CIP cleans the bag filter above the hole-plate. The used water is not re-circulated in this step.
The Hole plate CIP cleans the bottom side of the hole-plate and the snap ring area of the bag using a specially designed dual-purpose nozzle. During the plant operation on product, purged air is used to maintain the hole-plate free from deposits and thereby preventing the discolouring/denaturation. The water is re-circulated.
The Cylindrical Shell CIP is performed by means of Niro standard retractable CIP nozzles. The water is re-circulated.
After completing the predetermined CIP sequences, the bag filter is totally dried. The duration of CIP and drying of the bag filter can be adjusted to suit the actual requirements, which is estimated in the range of 6-10 hours.
Safeguarding
During drying operations there are the possibilities of principal dust hazards such as fire and explosions. In compliance with the Occupational Safety & Health (OSH), the bag filters are safeguarded to prevent personnel injury and equipment damage.
EXPLOSION RELIEF VENT SYSTEM
The units are equipped with explosion relief venting that is primarily determined based on the product characteristics and the effective volume of the bag filter. The rupture disc(s) are installed on the inlet process air duct to the
cylindrical part. Other preventive systems can be inc orporated in accordance with the requirements.
FIRE EXTINGUISHING SYSTEM
The bag filters are equipped with fire extinguishing deluge nozzles (i.e. sprinkler system) in order to reduce the fire hazards. The main purpose is to cool down the surfaces of the bag filter walls and the interior parts, whereas the bags will be destroyed. Other preventive systems can be incorporated in accordance with the requirements.
CONTROL SYSTEM
The control system is designed to ensure safe and reliable operation and following critical parameters are monitored and controlled:
- Pressure drop across hole-plate
- Pressure in outlet chamber
- Process air inlet/outlet temperatures
- Air Inlet temperature to cone heating section
- Air supply pressure to fluidized bottom
- Water pressure for fire extinguishing system
- Status of explosion relief vent(s)