Exploring SWAP Technology
SWAP technology does not require any injectors, nor Venturi or other accessories on the top of the bags to increase the secondary air in bag regeneration and it is basically based on:
- Special valves that allow a speed of mechanical opening of the membrane of about 20-40ms
- Maximum use of the law aerodynamics (impulse force)
This effect is related to physical parameters connected with:
- Cleaning pressure (from 2.0 to 3.0 bar)
- Optimized ratio between diameter holes in the blow pipe and diameter of bag.
The SWAP cleaning system can clean in ON-LINE mode bag with a length up to 12m; bags cleaning is performed by means of pneumatic valves (“full immersion” type) feeding up to 28 bags each (solution up to 30 bags is under evaluation in CTP facility).
The flagship of CTP Team in the field of ESP replacement and conversion is represented by the switch from the traditional pulse-jet cleaning system to the SWAP technology: a proven low-pressure technology for cleaning bags consisting in a sonic wave which travels all along the length of the bag at a velocity approx. Mach 1.
In the picture, from left side, the sonic wave travellin all along the bag (SWAP cleaning system).
The comparison between the different impact on the bag of the SWAP cleaning system on left and the traditional Venturi on right.
Bags cleaning and filter control is done through a control board which shall control the bags cleaning procedure sending information to the main control room concerning the pneumatic valve position and status. Bags cleaning cycle can be controlled both by filter Δp and by timer.
Main advantages of SWAP Technology:
- low working pressure (<3 bar)
- minimized open/close time of the valve (<40 ms)
- high efficiency regardless of bag length (up to 12m)
- high efficiency regardless of dust load
- reduced cleaning frequency and stress of bags
- extended bag lifetime
- simplified movement (no hysteresis and minimized inertia)
- low pressure drops (full immersion type valve inside the tank)
- negligible fluctuations of filter ∆p
- reduced quantity of cleaning valves (up to 28 bags per valve) and so lower energy consumption
- reduced maintenance cost
- no closing dampers closing to perform the cleaning.
- simplified filter construction, erection, operation, and maintenance
- high reliability of the system
Dual-phase CFD simulation
In ESP replacement or conversion the engineering design of the new filter try to optimise as much as possible how the dust reach the bags. In this direction good improvements has been achieved by a dual-phase CFD simulation. Such tool enables the analyses of the distribution not only of the gas entering the filter, but also of the particulate (dust) carried by the gas. As result the gas is evenly distributed among the bags, and plus also the dust is smoothly divided before approaching the bags. Therefore, each bag is subject to equal loads in terms of flowrate and particulate and so the life of bags can be predicted in specific way and not only in average.
A dual-phase CFD simulation allow to optimise the dust distribution and all the filter performances.
From left side, the original drawing of ESP filter, in blue the drawing of the fabric filter with bags 10 m long, in red the drawing of the final solution with bags 12m long.
Recent project highlights
In 2017 Tasek Corporation Behrad, Malaysia, has chosen CTP’s solution awarding his solid experience in managing the replacement of kiln&raw-mill filters replacing in brown-field configurations, when merging dedusting needs with the constraints intrinsic to each plant represents the key of the Project.
Indeed, a layout considering a Fabric Filter designed with bags 12m long and equipped with the SWAP technology, duly corroborated by a proper CFD simulation, was the only way of keeping existing footprint, foundations and supports, avoiding additional civil works and minimizing, in terms of time and cost, the impact of site activities.
The same has happened more recently, in 2020, when Austrian Gmunden plant, part of Rohrdorfer Zement, has conferred the order to CTP for the replacement of the existing kiln&raw-mill ESP into Bag Filter, provided that existing footprint, foundations and supports could be kept, the only option for respecting the original schedule also during the occurred pandemia. The Austrian project is actually on-going and will be commissioned in the first part of 2021.
From left side, the original drawing of ESP filter, in blue the drawing central manifold, in red the drawing of the final solution with two longitudinal gas distribution inlet ducts.
View of the new fabric filter installed in Tasek Corporation Beherad, Malaysia