Water Treatment: Protect your Investment
Process Water Treatment
Two of the main processes of industrial water treatment in petroleum industry are waste water
treatment and water injection treatment. A large amount of proper water treatment can lead to the
reaction of solids and bacteria within process.
Wastewater treatment is a process used
to convert wastewater into an effluent
that can be returned to the water cycle
with minimum impact on the
environment, or directly reused. The
latter is called water reclamation
because treated wastewater can then be
used for other purposes. The treatment
process takes place in a wastewater
treatment plant (WWTP), often referred
to as a Water Resource Recovery Facility
(WRRF) or a sewage treatment plant.
Pollutants in municipal wastewater
(households and small industries) are
removed or broken down.
Disposal of wastewaters from an industrial plant is a difficult and costly problem. Most petroleum
refineries, chemical and petrochemical plants have onsite facilities to treat their wastewaters so that
the pollutant concentrations in the treated wastewater comply with the local and/or national
regulations regarding disposal of wastewaters into community treatment plants or into rivers, lakes
or oceans. Constructed wetlands are being used in an increasing number of cases as they provided
high quality and productive on-site treatment. Other industrial processes that produce a lot of waste-
waters such as paper and pulp production has created environmental concern, leading to
development of processes to recycle water use within plants before they have to be cleaned and
disposed. Chemicals are used during wastewater treatment in an array of processes to expedite
disinfection. These chemical processes, which induce chemical reactions, are called chemical unit
processes, and are used alongside biological and physical cleaning processes to achieve various water
standards. There are several distinct chemical unit processes, including chemical coagulation,
chemical precipitation, chemical oxidation and advanced oxidation, ion exchange, and chemical
neutralization and stabilization, which can be applied to wastewater during cleaning.
In petroleum industry, chemicals aid in producing suitable water for discharge or injection. A wide
range of chemicals is available for water treating in petroleum industry. Offshore water injection
consists of injecting seawater into oil reservoirs to maintain or increase oil production. A number of
reservoirs, require that the water be treated before injection.
Oxygen scavenger
Chemical scavengers are used to remove dissolved oxygen from water-flow
streams. There are a number of compounds commercially available to remove
dissolved oxygen. These include:
sodium sulfite (Na 2 SO 3 )
sulfur dioxide (SO 2 )
sodium bisulphate (NaHSO 3 )
sodium metabisulfite (Na 2 S 2 O 5 )
ammonium bisulfite (NH 4 HSO 3 )
Flocculant / Coagulant
Vira’s water-clarification chemicals aid in coagulating and flocculating the oil
and solid particles into larger ones to enhance their separation from water.
Flocculation and coagulation treatment chemicals are used in water injection
treatment processes for solids removal, water clarification, lime softening,
sludge thickening, and solids dewatering. Coagulants neutralize the negative
electrical charge on particles, which destabilizes the forces keeping colloids
apart. Water treatment coagulants are comprised of positively charged
molecules that, when added to the water and mixed, accomplish this charge
neutralization. Inorganic coagulants, organic coagulants, or a combination of
both are typically used to treat water for suspended solids removal.
When an inorganic coagulant is added to water containing a colloidal
suspension, the cationic metal ion from the coagulant neutralizes the
negatively charged electric double layer of the colloid.
Flocculants gather the destabilized particles together and cause them to
agglomerate and drop out of solution.
Antifoaming agent (Antifoam)
Some water systems (e.g., seawater) have a tendency to create foam when subjected to high pressure-
drop or turbulence conditions. This foaming is very unpredictable and can cause enormous problems,
particularly in deaerator columns. In the deaerator, foaming may result in failure of the level control
on the base of the column and reduced oxygen-removal efficiency.
Antifoam chemicals are polyglycols or silicones contained in a solvent that is fully water-soluble or
water-dispersible. At dose levels usually less than 1 ppm, they act by decreasing the surface tension
of bubbles so that they expand and coalesce. They are dosed to the inlet of the deaerator before the
inlet distributor. In water-injection systems, the polyglycols are preferred because silicones produce
fine precipitates, which can cause injectivity loss. However, silicones may be required in difficult
applications, usually in low-temperature vacuum systems or when the foaming tendency is very high.
Corrosion inhibitor
Because piping and processing equipment of water injection plants are normally made of metals that
are in contact with produced water or seawater, chemical or electrochemical reactions will occur. Vira’s water injection corrosion inhibitors reduce the corrosion rate by interrupting the
electrochemical corrosion cell setup between the metal and the liquid or by stopping the deterioration
of metal by a chemical reaction. One method of interrupting the electrochemical cell is to form a film
on the metal surface, which stops the transfer of ions. One method of chemical protection uses an
absorption inhibitor, such as a surface-active amine, which forms a chemisorption bond to the metal,
rendering it incapable of dissolving into the fluid.
Vira’s corrosion inhibitors are selected by laboratory or field tests. Laboratory testing and evaluation
have the advantage of being quicker and less
expensive; however, inhibitor selection should
always be verified by a field test.
The following factors all have a significant effect on the corrosion rate of water injection plants:
the type of metal
Water pH
dissolved oxygen, dissolved salts, and acid gases in water
temperature, pressure, and fluid velocity
The most commonly used laboratory and field methods are:
the linear polarization resistance (LPR) test
electrical probes and corrosion coupons
Analysis Standards
Biocide
The types of biocide available are varied and are
selected on the basis of:
kill rate to anaerobic bacteria
kill rate to aerobic bacteria
ability to penetrate surface films
Quaternary ammonium compounds
Chlorinated phenols
Organometallic compounds
Sulfur organic compounds
THPS
Glutaraldehyde
بازدارنده رسوب
تغییرات فشار و دما بر حلالیت اجزای شیمیایی در آب تاثیر می گذارد و ممکن است سبب تشکیل شوند. بسته به ترکیبات موجود در آب، انواع مختلف رسوب می تواند در خطوط لوله، تجهیزات، سیستم کنترل، پمپ و … تشکیل شود. تشکیل رسوبات منجر به آسیب دیدن تاسیسات، انسداد و آلودگی آن ها می شود. گستره وسیعی از مواد شیمیایی بازدارنده رسوب توسط شرکت ویرا بسپار برتر تولید شده و فرمولاسیون های نوینی توسعه یافته است تا از تشکیل رسوبات در آب پیشگیری کند. انتخاب بازدارنده رسوب مناسب به نوع رسوبات و شرایط تشکیل مانند دما و فشار سیستم بستگی دارد.
شایع ترین رسوب های موجود در سیستم تولید یا آب دریا
کربنات (Carbonate)
سولفات (Sulfate)
فسفات (Phosphate)
کمپلکس سیلیکا- فلز (Metallic-silicate complexes)
سولفید (Sulfide)
سیلیکا (Silica)
اکسید (Oxide)
آمونیوم (Ammonium)
استاندارد ارزیابی
