overview
overview

Introduction

Arvand Petrochemical Co. is situated in southern of Iran. It has been constructed at site 3 of Bandar Imam Petrochemical Special Economic Zone, on the northern coast of the Persian Gulf. Sprawling on a

108-hectare, it seeks to help the country move towards self-sufficiency, industrial development and to provide the related local and downstream sector with the required raw material. Arvand was initially planned to implement olefins, MEG and EOG plants. But, the olefins plant was later transferred to Gachsaran petrochemical Co.

In 2002, the petrochemical industries Development Management Co.,a subsidiary to the National Petrochemical Co. (NPC) of Iran and a consortium of Uhbe of Germany and Sazeh of Iran entered into a

contract for the construction of Chlor-alkali(CA), ethylene dichloride (EDC), vinyl chloride monomer (VCM) and polyvinyl chloride (PVC) units. Arvand Petrochemical Co. was tasked with implementing these projects. The APC complex consists of EDC/VCM and PVC plants as well as an air separation unit (ASU),a CF unit, cooling towers, an air plant, a salt washing unit and brine transfer pipeline.lts output includes valuable products such as NaOH 50%, chlorine gas, Sodium hypochlorite, EDC, E-PVC and S-PVC. After the bidding, an EP contract was awarded to the Uhde- Sazeh consortium in 2003.

Arvand Production State And Application

Plant

Product

Capacity(t/y)

Application

CA

NaOH100%

660000

Detergents, paper & textile industries

NaOCl

16200

Detergents & hygiene product textile

Chloring Gas

585000

EDC plant, raw material for other petrochemical plants

ADC/VCM

EDC

890000

Solvents, resines, wax, Vcm 329,300 for sales

VCM

343000

Production of PVC

PVC

S-PVC

300000

Downstream industries

E_PVC

40000


Arvand feedstock

Plant

Feedstock

Capacity(t/y)

source

CA

Washed salt (100%)

1300000

sarbandar salt Pond

ADC/VCM

Ethylene

255000

Ethylene grid

Oxygen

57700

Arvand & fajr Petrochemical Co.

CL2

395000

CA Plant

HCL

203678

Karoon Petrochemical Co.

PVC

VCM

343000

EDC/VCM Plant

 


CA  plant
The plant is slated to produce 660,000 ton/year of caustic soda 100% or its equivalent 1,320,000 ton/year of caustic soda 50%. the plantconsists of two lines each producing half of the overall output.

Its major feedstock is brine with a density of 300-310 gr/lit. Thisrequired feed is obtained by processing 1,196,000 t/y of washed

Salt from the Sarbandar salt pond.

The plant can be classified into four major sections:

1-Brine filtration and precipitation

2-Cell room (electrolysis of sodium chloride)

3-Purification unit

4-Wastewater treatment

At the first section Na2 Co3

Sodium carbonate (Na2CO3)and sodium hydroxide (NaOH) are added to the input brine. Then, suspended solid impurities are settled and the brine is fed to the filtration unit where three different kinds of filters  namely anthracite, candle and ion-exchange filters are used

respectively to remove the suspended solid content, the dissolved solid content and  the calcium and magnesium impurities to a level of 20 ppb. (Due to the sensitivity of the membranes, the brine should have a high purity.)

The second section

Includes 24 BM 2.7 Electrolyzer. Each electrolyzerconsists  of 168electrolyzing cells 5 of which remain stays in stand- by mode.

In electrolyzing cells, the saturated brine will be decomposed electrically into CL- and Na+ with a current density of 5.46 KA/m2 and a current of 14.86 KA. Some amount of hydrogen is produced in the cathode

compartment of each cell.The CL- ions are oxidized and produce chlorine gas.And the Na+ ions, after passing through the membranes, combine with OH- ions and form NaOH or caustic soda.

The third section

Includes cooling, drying and concentration of chlor in which the chlorine gas produced by the electrolyzers will be pumped to the drying unit.

The out coming the chlorine gas will be sent to users.

At the concentration Unit, the 32% NaOH coming from the cells is concentrated ot 50%. This is then sent storage tank for sales.

In the acidification unit, portions of the freed hydrogen during hydrogen purification and the out coming chlor from the compressors are combined and burnt in a furnace. As a result, the obtained chloridric acid will convert to HCL in a column after absorbing water.

This will be used for the plants consumption. The combination of chlor and NaOH will produce sodium Hypochlorite.

In the water Treatment Unit, the waste water coming from various units will be neutralized and diluted. It is pumped to the nearby Fajr UT complex after its PH is regulated and its free chlorine is eliminated.

EDC/VCM Plant

The plant is designed to produce ethylene di- chloride (EDC) and vinyl chloride monomer (VCM) as feed for the production of polyvinyl chloride (PVC).

The process of PVC production consists of two phases:

Phase one

Phase one includes production and purification of EDC which is carried out at the Direct Chlorination, Oxy Chlorination and EDC Purification Units.

The Second phase

The second phase includes EDC Cracking, VCM Purification, Gas and Liquid Waste Incinerators and Storage Tanks Units. The chlorine gas produced at the Chlor-alkali Unit with react with the incoming ethylene within the reactor at the Direct Chlorination Unit yielding EDC. At the OxyChlorination reactor, HCL reacts with oxygen and ethylene producing with the EDC produced at the Direct Chlorination Unit will be sent to Unit 130 for purification. The purified EDC will be pumped to the intermediary

storage tanks in Unit 170 or the export storage tanks in Unit 180. Some portion of the purified EDC will be dispatched to the Cracking Unit and will yild VCM and HCL within the furnaces there. The HCL yielded at this unit will be sent back to the Oxy Chlorination Plant. The VCM produced from cracking reactions within the Cracking Unit (Unit140) will be transferred to Treatment and purification Unit (Unit150) where it will be purified and stored at the cicular storage tanks for use at the PVC Unit.

In this unit, medium peressure steam is also be produced using the heat yielded from burning waste gases.

PVC Plant

Producing PVC is one of the major goals  behind setting up

Arvand Petrochemical Complex. It is desingned to produce 300,000 tons per annum of S-PVC and 40,000 tons per annum of E-PVC for local consumption.

The excess produce will be exported to international markets.

The plant produces eight different grades of S-PVC powder and five different grades of E-PVC powder. The S-PVC and E-PVC Units consist of the following sections:

VCM &Dematerializad Water Supply

Dissolving & Catalysts-Production

Polymerization

Degassing

Drying & Bagging

The VCM produced at the EDC/VCM Plant is the major feedstock of the PVC Plant. The modern Vinnolittechnology is employed for the production of PVC which has improved the quality and the efficiency of the plant output.

At the S-PVC plant, the VCM feedstock from the EDC/VCM Unit is dehydrated and sent to polymerization section which consists of six batch reactors.They use Intercooler technology that helps minimize production cost and improve the efficiency of this section.

In the polymerization unit of the S-PVC Plant, PVC is producedsuspension method within the polymerization reactors. Meanwhile,in addition to the VCM feed, a number of chemicals such as catalysts,dispersants are injected in to reactors along with VCM.

The out coming suspension from reactors, enters dehydrators after passing through degassing columns. It is dehydrated by centrifuges and is conveyed to dryers.

The suspension produced in the reactors is dehydrated within centrifuges. The product is dried by hot air from dryers.

The final PVC powder product is conveyed to bagging section.

The bagged product is stored at the plant’s warehouses.

In the E-PVC Plant, much of the production process resembles that of the S-PVC Plant. The polymerization process takes place ina continuous form.

The polymerization section of the E-PVC Plant comprises three reactors that operate continuously and yield PVC by an emulsion process.

In these reactors, VCM is converted to PVC. The produced latex iscontinuously injected into degassing and then to dryers sections.

The 50% concentrated latex is then turned into PVC by dryers using hot air.

The obtained PVC granules are put through a sieve to control the size of the granules. The sieved granules are then conveyed to silos and eventually end up in storehouses after they are bagged.

In addition to the feedstock that is used for the production of E-PVC and S-PVC , a number of substances are also used as additives.

They include dispersant agents, catalysts, stoppers, emulsifiers,

stabilizers, inhibitors, cross-linkings, de-foamers to name some of the most important ones. In a broad comparison, at the S-PVC Plant the PVC cake is dehydrated by centrifuges and at the E-PVC Plant latex is

concentrated by employing the Memberane technology. At both plants, hot and dried air is used  to obtain PVC power.

The dried powder obtained at both plants is later sieved and eventually bagged and stored in warehouses.

Sulphuric Acid Concentration (SAC) Unit

The Unit is designed to recover the sulphuric acid required to be used by the CA Plant. The 78% sulphuric acid current from the CA Plant is purified and concentrated within the stripper column yielding 96% acid which is returned to the CA Plant after going through certain processes. The SAC Unit has a capacity of 32 ton per day.

ASU Plant

The plant, built by Hangzhou Fortune Group of China, is designed to supply the Oxy Chlorination with the oxygen it requires for its operation. It comprises of two identical units each with a capacity of 7,500 normal cubic meters per hour of oxygen and 7,500 normal cubic meters per hour of nitrogen. The two unit will be built on a piece of land covering an area of 1 hectare.

The Oxy Chlorination will require 59,400 tons of oxygen per year.

Plant Air

Arvand Complex consumes 15343 normal cubic meters per hour of industrial air. The Plat Air Unit was built to supply this requirement. The excess volume is supplied to the neighbouring complexes. To this end, three centrifugal compressors, each with a capacity of 8000 normal cubic meters per hour, built by Kobelco of japan, were bought and put in operation.

Salt Washing Plant

Salt saturation pits are 22 km from the boundary of Arvand complex.

It supplies the concentrated brine that the complex requires for processing at its Chlor-alkali (CA) Plant. The process is designed so as to either produce brine with a concentration of 300-310 g/lit from sea water or out of the diluted brine which is returned from the CA Plant.

The Chlor-alkali plant comprises three brine concentration saturates each with a capacity of 480 cubic meters.

The concentrated brine is pumped from a distance of 22 kilometers and is stored in a tank built at Unit 020 in the CA plant.

Before it is sent to the next unit, the brine is passed through exchangers and is warmed by the diluted brine returning from the unit. The diluted brine is then stored in another tank

and is sent to concentration pond where it is concentrated.