Sodium hypochlorite (Seawater System)

In water treatments the on-site generated hypochlorite from seawater is a disinfection practice, obtained applying a certain amount of electrical current  to salty water through an electrochemical process.
Thanks to the integration of qualified personnel to the existing structure and the creation of strategic alliances, Gemwater is able to realize any size of plant, following any type of Standard requirement from Customer and Final Users.

The amount and velocity in formation of biological fouling and growth of shellfish, algae, mollusks and slime are usual inconvenience, due to un-natural variations in temperature, chemical and physical parameters, in cooling processes or in process water.
The marine organisms can also increase corrosion by reducing oxygen diffusion which can significantly shorten affected equipment’s operational life. As a consequence, bio-fouling reduces efficiency and safety of these processes by restricting the flows in pipe runs and reducing heat transfer across heat exchangers and condensers. In membrane desalination and separation processes, bio-fouling is a very critical operating issue.

These processes are present in many of the industrial fields such as in:
petrochemical plants;
re-gasification of liquefied natural gas (LNG);
oil offshore platforms;
FPSO - Floating Production Storage and Offloading (Top side and Sea Bed);
power plants.

Gemwater supplies different types of Hypochlorite production Plants, depending on the size, on the environmental condition, on Client’s specification and Standard requirements.

In platforms or in FPSO, the requirement of Sodium Hypochlorite production is accompanied with the necessity to have compact designs for easy handling and maintenance, avoiding as possible chemicals handling (as HCl) .

Another requirement is that the electro-chlorination package can be installed  in  Zone 2,  or in  Zone 1, rarely in Safe Area.
Gemwater provides all engineering services  for the good and reliable execution of the  electro- chlorination unit, in particular considering:
process, mechanical, electrical and instrumental design of the equipment;
manufacturer/procurement of the equipment, inspection, controls and FAT at proper works shops;
drawings, flow sheets, data books, operating instruction and maintenance manuals, certificates, etc;
packing and delivery.

Here below are underlined the evident technical advantages of our designed Electrolysers:
no acid cleaning. Choice of  the better performing water speed  in the pipes in order to avoid scaling effects;
long life of electrodes (guaranteed for a period of not less than 5 years);
high quality and efficient electrode material and configuration, so less power consumption,
  infrequent shutdown or turndown periods;
simply operation and low maintenance. The electrolysers are designed to perform replacement of an electrode
  assembly with a spare assembly, in a very short time (minimal operator attention and attending);
low by products formation by the electro-chlorination process as bromate, chlorates ions;
supplied package is mainly customized according to Client’s technical engineering specifications and designed
  to resist against the hard and critical ambient outdoor condition, typical in off-shore application
 (Hazardous and Explosion area);
no potential dangerous condition to operator and to environmental. All plant is designed complying to restrict
  and recognized international standards and rules;
all package will be skid preassembled, minimizing all client‘s erection works at site;
no special capital spare parts to be purchased;
low footprint requirement;
easy future expansions;
low operating cost and low power consumption.

The electrodes cells are named CTE’s (concentric tubular electrolysers). In most cases, CTE’s are used in multiples of two, three or four.  

All CTE’s are constructed of two concentric mounted titanium tubes called “inner” and “outer” tubes. These are the electrodes (anodes & cathodes).    
The real innovation of this model CTE  (Concentric Tubular Electrolysers) has been created to be completely electrically insulated for increasing Health & Safety.
The  THREETUBE SAFETY CTE is basically a conventional CTE with exactly the same operational and performance characteristics. The only difference is that it is mounted inside an electrically insulated “third” outer PVC tube/casing, hence the name “THREETUBE SAFETY CTE”.
This PVC tube/casing holds all the inner and outer titanium tubes in position and forms part of the pressurized hydraulic system.

Gemwater applies  the plate type electrode in desalination plant, in Power Plant Cooling Cycle, everywtime the production required is high, and one of the requirement is low electrical consumtion, high reliability, high efficiency of the plant.      
The injection of hypochlorite in the cooling water circuit or in membrane process treatments provides efficient protection to the equipment.

Seawater is an inexpensive source of salt. When these sources are not available or suitable, artificial brine is prepared using salt and fresh water.
Another way to provide this biocide, is to purchase it as commercial.
Some of the inconvenience of this solution are the build-up of hard deposits by reaction of excess alkalinity with the substances dissolved in water; a very serious limit in the use of chlorine is the  safety hazard connected with the transportation, storage and handling of this as a gas.

The on-site production create independence of the client from the outside suppliers and market price variations.

For all the above, the on-site generation of sodium hypochlorite solution from seawater is the cheapest and most safe way to produce this powerful biocide.

The plant as designed will have the following technical characteristics and environmental benefits:
ROI (Return Of Investment) very effective;
high efficiency and updated process technology for the electrodes;  
sodium Hypochlorite is much less hazardous than Gas-Chlorine; no certified operator is requested to
  handle this chemical;  
as Sodium hypochlorite tend to partially decompose if handled, the on-site production prevent form product losses;
storage, dosing equipment and procedures are easier to install and operate;
no costs for transportation;
minimum costs for maintenance;
no time and cost for documentation (material safety data sheet) and permission by local authorities;
doesn’t classify the area.

The proposed plant shall be installed into a dedicated building or within a container with accessories and air conditioning facilities to protect all equipment against atmospheric conditions.