Polypropylene plants

Figure 1 shows part of a solvent phase polypropylene plant. The plant consists of three process lines, denoted A, B, and C. During a risk assessment review, a scenario was identified that involved a release of reactor contents from a location near the west end of the A line. Estimates are needed of the blast overpressures that would occur if the resulting cloud of vapor, mist, and power ignites. 

Figure 1. Layout of the solvent phase polypropylene plant with the leak location.

Figure 8.36 Photograph of a membrane unit used to recover nitrogen and propylene from a polypropylene plant vent gas...

Commercial plants Ten polypropylene plants are in operation or under construction, with capacities ranging from 65,000 tpy to 360,000 tpy. 

Borstar A catalytic process for polymerizing ethylene or propylene, subdivided into Borstar PE and Borstar PP. Use of two reactors — a loop reactor and a gas-phase reactor — allows better control of molecular weight distribution. The loop reactor operates under supercritical conditions to avoid bubble formation. Either Ziegler-Natta or metallocene catalysts can be used. The latest version, Borstar PE 2G, uses a single, multizone gas-phase reactor to make polymers that have bimodal molecular weight distributions. Developed by Borealis A/S. The first commercial unit, for polyethylene, was installed in Porvoo, Finland, in 1995. The first polypropylene plant was operated by Borealis in Schwechat, Austria, in 2000. In 2005, Borstar s total capacity for PE and PP was 1.3 million tons. 

Petrofin [Process enhancement through recovery of olefins] A process for recovering olefins (ethylene and propylene) from polymerization processes by adsorption on zeolite 4A. Developed by BOC and used at Montell s polypropylene plant at Lake Charles, LA. First demonstrated in 1997. 

VaporSep A family of separation processes, based on membranes that are selectively permeable to organic vapors. Developed by Membrane Technology Research, CA, in the 1990s and used by DSM in its polypropylene plant to separate propylene from nitrogen. The membrane is a three-layer sandwich, packaged in spiral modules. 

Philippines [42-43]. Financial problems, tariff restrictions, and political problems have dealt blows to the building of a major petrochemical complex in the Philippines. In the late 1980s, plans were made, but in 1993 they appeared to be dead. The plans were revived in 1996-1997, however. In the mid-1990s, polymer plants based on imported feedstocks were planned and, ultimately, a steam cracker. In the long range, polystyrene, LLDPE/HDPE, and polypropylene plants are being considered. Seven CPI projects were under way in early 1999 [13]. 

Energy Consumption. Without the need for de-ashing and diluent distillation, and with a more efficient operation due to the higher pressure level in the reactor, major reductions (ca. 50 % expressed in terms of fuel equivalent per tonne of polymer) in the energy consumption of the modern polypropylene plant have been achieved. Figure 95... 

The recovery of hydrocarbon monomers from ethylene in polyethylene and polypropylene plants is actually the largest application of vapor separation membranes. After the production of the polyolefin resin, there are unreacted monomer and hydrocarbon solvents dissolved in the resin powder that must be separated in order to reuse the polymer. The traditional application involves stripping with hot nitrogen in a column known as a degassing bin. The values of nitrogen and monomer are both high therefore, the recovery and reuse of these components are of great interest. For this purpose, a membrane operation is profitably used. It consists of two membrane units in series where the off-gas... 

The next year, 1990, Lyondell purchased, from the Rexene Products Company, the low-density polyethylene and polypropylene plants built in Bayport, Texas, by El Paso Products Company in the 1970s. In 1995, the Alathon HOPE business was acquired from Occidental Chemical Corporation for 356 million. In 1997, Lyondell combined its petrochemical and polymer businesses with those of Millennium Chemicals (which itself had recently been formed from the Quanmm Chemical Company, which had been the largest producer of polyethylene in the USA) to form Equistar Chemicals as a joint venture. Occidental Chemical s petrochemical business became the third part of Equistar in 1998. 

Figure 14.12 Photograph of a membrane propylene recovery system installed at a polypropylene plant. This unit recovers approximately 450 kg/h of hydrocarbons. Image courtesy of www.mtrlnc.com, Copyright 2010 mtrinc...

The wastewater was collected from the effluent treatment plant of a polypropylene plant production unit situated in northern India. The wastewater was stored at 4°C in a refrigerator in the laboratory and was subsequently used in the experiments without any dilution. All chemicals used in the experiments were of analytical reagent (AR) grade. Copper sulphate (CUSO4 5H2O), anhydrous ferric chloride (FeCy and ferrous sulphate (PeS04 7H2O) were procured from M/S, RFCL, New Delhi. 

Characteristics of Polypropylene Plant Wastewater The characteristics of propylene plant wastewater as analysed by the petrochemical plant are presented in Table 6.21. The waste-water consisted of both organic and inorganic substances and was slightly acidic in nature (pH 5.3). Its COD (3520 mg/L) and BOD (1132 mg/L) were very high and the parameters were most predominant. 

Effect of temperature on COD reduction of polypropylene plant effluent during thermolysis. CODq = 3520 mg/L, = 3 kg/m, pHo = 6.53, P = self-pressure, (a) COD reduction with time, (b) First-order kinetics at different temperatures. 

The kinetic equation for catalytic thermolysis of the polypropylene plant effluent for temperature in the range of 40-160°C, catalyst mass loading in the range of 2-5 kg m and at pHfl = 6.65 may, thus, be written as... 

Arrhennius plot for thermolysis of polypropylene plant effluent. 

Effect of different catalysts on COD reduction of polypropylene plant effluent. CODq = 3520 mg/L, = 3 kg/m, ... 

The monomer consumption data of the HDPE process is slightly different for the polypropylene process due to variable purity of the monomer raw material used by polypropylene plants. 

FIG. 3 (a) How the fourth generation catalyst changes a polypropylene plant, (b) Yields obtained after 2 hr. pol5unerization time, 50°C and 5 atm. with different cocatalytic systems. 

Also, in Europe there were 32 polypropylene plants owned by 13 different companies in 2010. These include Basell with nine plants. Borealis with six plants, Domo with one plant, Dow Chemical with one plant, ExxonMobil with two plants, INEOS with four plants, Polychim with one plant, Repsol YPF with two, Sabic Europe with... 

The SPS polymerization is very unique. Liquid styrene monomer is polymerized with homogeneous catalysts and produces SPS powder in the reactor. This is in contrast to Ziegler-Natta catalysts, which have solid components and powders that can easily be obtained by the growth of the solid components in bulk polyethylene and polypropylene plants. Under limited operational conditions and with a special equipment, SPS powder can be obtained. The SPS polymerization systems are very difficult to design. There are three types of SPS reactor processes from the patent information. 

Synthesis The early polypropylene plants used a slurry process adopted from polyethylene technology. An inert liquid hydrocarbon diluent, such as hexane, was stirred in an autoclave at temperatures and pressures sufficient to keep 10 to 20 percent of the propylene monomer concentrated in the liquid phase. The traditional catalyst system was the crystalline, violet form of TiCla and AlCl (C2Hs)2- Isotactic polymer particles... 

In Malaysia, a number of companies both foreign and local, have expressed considerable interests to establish petrochemical operations. The list of such companies include Kellogg-Thyssen which recently announced that it will establish a US 1 billion petrochemical complex producing polyolefines and aromatics from crude oil and/or naphtha. Then there is Himont and C.T. Chao, a Taiwan-US joint venture, proposing to set up a polypropylene plant in Pasir Gudang, Johor in the south of peninsular Malaysia. Petronas, the National Oil Company, itself has formed a joint-venture company with Neste Oy of Finland and Idemitsu Petrochemical Co. Ltd of Japan to establish an MTBE and Polypropylene Project in Kuantan, Pahang on the East Coast of Peninsular Malaysia. 

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