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Reduce manufacturing cost and cut down solvent emission levels with well designed CHEMIPRO R solvent recovery systems.
Organic solvents find extensive use in the Chemical Industry, Printing, Packaging, and Paint Industry. Due to their high volatility and good solubility in water as in case of the most commonly used solvents, substantial quantities of solvents gets evaporated into the air stream and find their way out of factories along with wash and rinse water streams. Apart from losing useful revenue through such uncontrolled losses, the atmosphere too gets polluted. With environmental regulations getting stricter by the day, control measures have become necessary to recover such solvents.
Which are the industries that can use solvent recovery systems?
- printing and packaging industry
- bulk drug manufacturing industry
- herbal extraction plants
Typical solvent losses in the printing & packaging industry:
In the printing and packaging industry, organic solvents like ethyl acetate, MEK, MIBK, toluene, Isopropyl alcohol etc. are used to increase the mobility of printing inks and coating solutions that facilitates easy application of the ink on the substrate. In the case of coating machines, the coating medium, which may be a lacquer or may be an adhesive, is applied through a solvent medium on a substrate before a second substrate is made to adhere to it. Though water-based inks and adhesives have been developed for the printing and packaging industry, converters by and large use solvent based inks and adhesives to keep the drying costs low and production rates high since the latent heat requirements for organic solvents are considerably lower than that of water.
Typically, a high speed gravure printing machine operating at 300 M/min speed and printing 3.2 gsm solid ink on a 1.27 M wide substrate discharges about 216 kgs/hr solvent amounting to the release of about 130 tonnes of the solvent into the atmosphere every month on continuous production. The company therefore loses about INR 6 crores equivalent to about 1.2 million USD worth of solvent every year.
Typical solvent losses in the bulk drug manufacturing industry:
A solvent audit carried out by us for a multinational bulk drug manufacturing facility indicated only 9 tonnes to have been recovered and disposed off to an outside agency out of a total quantity of 136 tonnes organic solvents purchased during the year. In other words, with no solvent being actually getting consumed as a reactant in the process of bulk drug manufacture, more than 90 % of the solvents have been escaping into the environment. This translates to a loss of revenue to the tune of about half a crore of Indian rupees every year equivalent to about 0.1 million USD.
Typical solvent losses in the herbal extraction plants:
A walk-through solvent audit carried out by us for a herbal extraction plant revealed an average of about 84 tonnes of organic solvents being lost to atmosphere every month. This company, therefore, have been losing a revenue of around IRS. 5 crores annually ie. about one million USD.
The above are examples of a few medium scale industries in three typical sectors, which are major consumers of organic solvents. There are hundreds of industries in these sectors and the total worth of solvents that is used but not recovered may run into millions of rupees or dollars.
Solvent recovery through adsorption on activated carbon:
A typical solvent recovery plant works on the principle of adsorbing the solvents on an adsorbent bed like activated carbon, etc. which is a physical process. During adsorption, solvent molecules physically attach themselves by van-dar-walls forces to the numerous pores available in every particle of the activated carbon that comes in contact with the VOC containing gases . On saturation of the activated carbon when most of the pores on the surface of the activated carbon particles get filled with the solvent molecules, the exhausted bed is regenerated with steam whereby the solvent molecules adhering to the activated carbon particles get evaporated and the vapor mixture of solvent and water travels to the surface condenser where the mixture condenses and collects in a receiver. In the case of solvents being miscible with water, the solvent-water mixture is separated through common techniques of distillation. In the situation where the solvent is immiscible in water, the solvent is separated from the water by gravity separation. The exhausted bed is then dried with a stream of hot air being passed through the bed before being put on stream for the next cycle. Typically, a minimum of two beds of activated carbon are used where one bed is in adsorption mode while the other is on desorption mode.
Providing turnkey solution to recover organic solvents from exhaust air streams involves the following services:
- Solvent audits through mass balance and process studies.
- Design of capturing mechanisms for solvent laden air streams
- Design of distillation systems for recovery of solvents from liquid streams
- Energy recovery through oxidation of solvents in exhaust air streams and using the exothermic heat to substitute the use of fuels
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