Here is the process for the production of hydrogen gas through electrolytic Knowel's cells -

• Tanks and bells are welded by special quality electrodes to avoid the process embrittling between hydrogen and caustic soda.
• Bells are manufactured out of C.R.C. sheets that are specially recommended for caustic soda handling.
• The Asbestos diaphragm cloth is manufactured from 100% pure long fiber asbestos without cellulose core and closely woven to avoid pin holes.
• Extra length of cloth is provided at the bottom to guard against bye-pass of gases.
• Ebonite insulators are tested against warping under high temperature and they are checked by meger for infinity resistance.
• Nickelling of anodes is done under strict supervision for a minimum of .002 thick coarse deposit and each plate is tested chemically for pores.

There are so many details we take care of, like -

The performance and long life of the electrolyser depends on the quality of feed water. As only hydrogen and oxygen together with some water vapour escape from the electrolyser, each impurity introduced with the feed water will accumulate in electrolyte, i.e. chloride, sulphate and iron. The former two will have harmful effect on nickel metal which leads to heavy corrosion and the later will cause impure oxygen gas.

Electrolysis process description

Purpose of the plant is production of hydrogen and oxygen. A water flow enters in the electrolytic cells where, through an electric current, it happens the following electrochemical reaction.

H₂O -----1/2 O₂ + H₂

Hydrogen and oxygen, so produced, are stored separately in their proper circuits and tanks. End user can use the required gas quantity proportionally to his necessity : the generator provides automatically to deliver the necessary gases (O₂ and H₂).

Production pressure of both gases is > 4 bar, and it is kept constant by an electronic control equipment.

Plant Description -
Hydrogen Generator Model G 16/d

Generator G 16/d is composed by:

n 1 electrolitic cells with support slide and fixing belts in inox steel. All connections and pipelines are in inox steel and chassis in painted carbon steel. It is composed by:

• "Structural tank" in the lower level, in inox steel for restraining of all liquids present in the generator in case of accidental lack.
• Skid in carbonium steel, all painted and fixed to the "structural tank" in order to guarantee a complete painting.
• Shell composed by four different compartments (A-cells, B transformer, C- electrical and electronics parts, D- electro pneumatics devices.)

Internal tanks in inox steel, with function of bi. phasic separators, with condensators with air and liquid exchangers. Furthermore there are present all the necessary devices for gases treatment, like pressures balancing and regulation automatic discharge system of condenses.

Pipelines and threaded connections in inox steel AISI304. Internal exchangers by tube nest for coolings gases coming out from separators groups.

n.1 process off-gas discharges device. The process off- gas of the generator, i.e oxygen and hydrogen, will have an external discharge from the cabinet by a proper pipeline

Plant control instruments
In the front side of the generator, inside a separate shaft (insulated from production shaft of the degree IP65), it is installed the electronic control panel with relevant PLC and power interface: in the lower level there in another shaft (separated from the first one) containing power transformer

Performances

Plant performances

Hydrogen=99.8+ 2 by Vol.
Oxygen =99.5+ 0.5 by Vol.

Max. 250 mm of water column- sufficient for storage in low pressure gas holders. When oxygen is not required to store in gas holder it is vented through pressure balancing tank to atmosphere.

(in filter press type) : NIL
(in Knowel type) : Minor leakage of gases connot be detected, which cause caustic atomsphere in the cell room.

(in filter press type) : NIL
(in Knowel type) : 1. In case of loose electrical connection.
2. In case of blocking of the cells from bottom by disposition of solid caustic and carbonate.
3. Short circuit due to leakage of electrolytes.