Acid Gas Removal and Sulphur Recovery Unit
The undesirable elements, like sulphur, nitrogen and water, are removed from crude
oil by different chemical treatment methods such as merox treatment, olamine
process, glycol treatment, etc. During merox treatment, the mercaptans are removed.
The sulphur dioxide, nitrogen dioxide and carbon dioxide are removed in olamine
process using amine solution. For removal of water, glycol is used. Generally, the
noxious wastes of these units are mercaptans, organic acids, spent amine solution
and spent glycol (Central Pollution Control Board, India 2018).
Heat Exchanger
All petroleum industries use heat exchangers for heating or cooling the different
streams. Routine maintenance of the heat exchangers is required by removing sludge
and scale from tubes, pipes and bundles to maintain efficiency. The effluents from
heat exchangers contain oily sludge including heavy metals like lead, chromium, etc.
(Central Pollution Control Board, India 2018).
Cooling Tower
Cooling tower plays an important role in petroleum refineries. After cooling the
different fractions of hydrocarbons using water in heat exchangers, this hot process
water is passed through the cooling tower for heat removal. But sometimes, the
process water is contaminated with hydrocarbons due to some leakage problems.
From the cooling tower, cold water is mixed with oily sour water, suspended and
dissolved solids, etc. This wastewater has high chemical oxygen demand, biochemical oxygen demand and pH. So, this cooling water blowdown must be treated in the
refinery effluent plant before reuse (Central Pollution Control Board, India 2018;
International Petroleum Industry Environmental Conservation Association 2010).
Blowdown
Blow-down system is a collection unit in which most refinery process units are
manifolded to offer safe handling and disposal of liquid and gases from different
units. The liquid from the blow-down system typically contains water contaminated
with hydrocarbons, sulphur compounds, heavy metals, organic nitrogen, different
solvents, etc. which is dispatched to the wastewater treatment plant (Central Pollution Control Board, India 2018; International Petroleum Industry Environmental
Conservation Association 2010). Table 8.1 shows the characteristics of effluents
from refinery units.
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M. Samanta and D. Mitra
The undesirable elements, like sulphur, nitrogen and water, are removed from crude
oil by different chemical treatment methods such as merox treatment, olamine
process, glycol treatment, etc. During merox treatment, the mercaptans are removed.
The sulphur dioxide, nitrogen dioxide and carbon dioxide are removed in olamine
process using amine solution. For removal of water, glycol is used. Generally, the
noxious wastes of these units are mercaptans, organic acids, spent amine solution
and spent glycol (Central Pollution Control Board, India 2018).
Heat Exchanger
All petroleum industries use heat exchangers for heating or cooling the different
streams. Routine maintenance of the heat exchangers is required by removing sludge
and scale from tubes, pipes and bundles to maintain efficiency. The effluents from
heat exchangers contain oily sludge including heavy metals like lead, chromium, etc.
(Central Pollution Control Board, India 2018).
Cooling Tower
Cooling tower plays an important role in petroleum refineries. After cooling the
different fractions of hydrocarbons using water in heat exchangers, this hot process
water is passed through the cooling tower for heat removal. But sometimes, the
process water is contaminated with hydrocarbons due to some leakage problems.
From the cooling tower, cold water is mixed with oily sour water, suspended and
dissolved solids, etc. This wastewater has high chemical oxygen demand, biochemical oxygen demand and pH. So, this cooling water blowdown must be treated in the
refinery effluent plant before reuse (Central Pollution Control Board, India 2018;
International Petroleum Industry Environmental Conservation Association 2010).
Blowdown
Blow-down system is a collection unit in which most refinery process units are
manifolded to offer safe handling and disposal of liquid and gases from different
units. The liquid from the blow-down system typically contains water contaminated
with hydrocarbons, sulphur compounds, heavy metals, organic nitrogen, different
solvents, etc. which is dispatched to the wastewater treatment plant (Central Pollution Control Board, India 2018; International Petroleum Industry Environmental
Conservation Association 2010). Table 8.1 shows the characteristics of effluents
from refinery units.
236
M. Samanta and D. Mitra