Planning ion exchanger system
The planning of an ion exchanger system as a recirculation system essentially depends on the ingredients, but also on the temperature of the medium. Due to the required anion exchangers, the temperature is typically limited to 60°C (in exceptional cases 70°C), as above this temperature the functional groups of the anion exchanger are irreversibly lost, i.e. it is inactivated.
With regard to the circulation streams to be treated, it is first necessary to select the appropriate wastewater streams. No precipitation should occur at this point (if possible) in a common storage tank for the circulation ion exchanger system, otherwise the streams must be separated. Any impurities (e.g. particles, apolar substances, biology, manganese, tin, oils, greases, oxidative substances) in wastewater streams must either be separated or pretreated separately or they exclude the entire wastewater stream.
Depending on the load of the combined water and the desired volume stream, the actual design of the ion exchanger system is then carried out, which is typically expressed in BV/h, i.e. bed volume (= net volume of ion exchanger in a column) per hour. The required quantity of ion exchanger in L is taken into account depending on the required layer height, the ionogenic binding behaviour of the substances to be cleaned and the required speed of the volume stream in m/h.
The following reference values apply:
5 BV/h = very slow, very long contact time
10 BV/h = slow, long contact time
20 BV/h = typical speed
40 BV/h = fast, short contact time
The ion exchange columns can basically be operated in two different directions, in the so-called fixed bed process (normal case) or in the floating bed process (e.g. if blockages of the resin bed would otherwise occur).
After loading the ion exchangers, the resins are regenerated in an ion exchanger circulation system. For systems with long service lives, this can also be carried out externally in a central regeneration station for ion exchangers or the regeneration can be carried out stationary on site. Replacement or exchange of ion exchangers for new ion exchangers is only necessary in rare cases.
Regeneration is typically carried out using the designated chemicals hydrochloric acid and caustic soda, but other acids and alkalis may also be used, or in a multi-stage process, often known as conditioning, and subsequent rinsing of the resin bed. Like the operation of the resins, regeneration can basically take place in two directions, such as operation in a fixed bed in a direct current or counter-current process. Both processes have their advantages and disadvantages and depend on the use of the ion exchanger system and the substances bound on it. Depending on the results of the planning, the ion exchanger system is either designed as an on-site self-regenerating system or, for example, as an ion exchanger system to be regenerated externally due to the low quantity
Typically, ion exchanger circulation systems have two to three internal circuits to prevent adverse effects during operation of the system.
The ion exchanger system as a recirculation system is typically expected as a water-saving measure as part of the indirect discharger permit or the indirect discharger application (or a justification as to why such a system is not used).
If the system is used to produce demineralized water without recirculation, either a so-called demineralization system is planned or, for small quantities, a demineralization cartridge or, alternatively, a reverse osmosis system for industry.
Do you have further questions about the planning, design, maintenance or operation of an ion exchanger system?
Please also note our further information on the ion exchanger.
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