Saving Energy Cost for a Leading Hydrogen Peroxide Manufacturer
- Jiaur Mallick, Application Engineer II, WPS Heavy-West & South Division

The following case study explains how Nalco's PermaCare Programme improved reverse osmosis process and saved significant costs for a leading hydrogen peroxide manufacturer. The programme helped the company achieve power reduction of 43,800 kWh due to the optimised feed pressure and save power cost by USD 5,568 per year.

Established in 1954, this listed company is a pioneer in India for peroxygen chemicals and the largest manufacturer of hydrogen peroxide in India, with an installed capacity of 84,000 MTPA.

The company offers hydrogen peroxide, which is used in various industries for bleaching, chemical synthesis, environmental control/ effluent treatment and sterilisation.

The production of hydrogen peroxide requires demineralised water and this is produced from the permeate water using Reverse Osmosis (RO). The RO solution was not performing up to par, registering a low water flow rate of 45m3/hour , which was 20-25 percent lower than planned. Feed pressure had to be increased during Stage 1. Due to increased feed pressure and reduced permeate flow, they cleaned membranes every week. This also led to peripheral complications in fouling as a result of contaminants accumulating on the membrane surface.

It was evident to the customer that increasing the feed pressure was not a sustainable, long- term solution.

The customer recognised the challenge and called on the expertise of Nalco in India.

To ascertain the areas of concerns, it was important to have the right data. Nalco India conducted a thorough mechanical, operational and chemical survey . Leveraging Nalco's extensive expertise and industry know-how, the specialist team was able to ascertain the plant's condition and pinpoint areas of improvement in the pre-treatment regime. This included a detailed analysis of chemical dose control, residuals monitoring and optimisation to bring the customer's pre-treatment programme to a new level of performance .

Leveraging global best practices, Nalco was able to provide proven solutions and customised a tailored approach to address shortcomings in the RO process and introduce operational efficiency in the membrane maintenance.

Nalco PermaCare was introduced to address specific issues in aluminum and silica traces in the feed water and apply the corrective measures to optimise the RO process, levelling off fouling. Nalco applied the antiscalant to prevent scaling and recommended cleaning of the RO membrane under Nalco's supervision. A monitoring regimen was implemented to provide a benchmark of feed pressure and permeate flow, as well as to document improvement post Nalco implementation.

Since implementation in early 2013, the customer has achieved tangible benefits in operational efficiency, risk reduction and capital expenditure avoidance. RO feed pressure and permeate flow recovered to its design value. Feed pressure decreased from 8kg/cm2 to 6kg/cm2 in average. Permeate flow increased from 27m3/hour to 31m3/hour in average, and the recovery ratio raised from 68 percent to 75 percent. Cleaning frequency reduced from once every week to once every month. Specifically, throughput was increased, and the membrane replacement was reduced. The total cost of operation decreased by more than USD 26,000 per year.

Reduced Chemical Usage: The EDTA was reduced by 20 kgs per cleaning, total 1,040 kgs per year (52 times of cleaning for each year). The citric acid/caustic was reduced by 15 kgs per cleaning, total 780 kgs per year. The overall chemical usage reduction cost was USD 2,000.

Saved Water: As the cleaning frequency was decreased from once every week to once every month, the demineralised water used for flushing was reduced by 2,200 m3, annually saving USD 1,860.

Protected Membrane: The membrane life was prolonged from 2 years to 5 years due to less cleaning frequency, saving the equivalent membrane replace cost by USD 14,240.

Reduced Maintenance: The man hours were reduced from 576 hours to 180 hours per year due to less maintenance work, achieving the manpower cost reduction of USD 3,050.

Saved Energy: The power consumption was reduced by 43,800 kWh due to the optimised feed pressure, saving USD 5,570 per year.

With the implementation of the Nalco PermaCare program and best global practices introduced by the Nalco team, the client was able to achieve a significant increase in RO permeate output, reduction in feed pressure thus saving power cost, prolonged membrane life and asset maintenance cost reduction