Tubular reactor, LDPE

Stamicarbon bv Polyethylene, LDPE Ethylene Advanced Clean Tubular Reactor LDPE reliable, flexible and low-cost for any PE product lines sizes up to 200,000 tpy 9 2000... 

EniChem through Snamprogetti EniChem process, high pressure, autoclave or tubular reactor. LDPE (density 918-935 kg/m ), MFI = 0.1-400 g/10 min. EVA copolymer (3-40% VA content) for film, injection moulding, profiles, sheets, cable sheetings, crosslinking, and foaming. 

LDPE is produced in either a stirred autoclave or a tubular reactor total domestic production, divided between the two systems at 45% for tubular and 55% for autoclave, is estimated to be 3.4 million metric tons per year (5). Neither process has gained a clear advantage over the other, although all new or added capacity production in the 1990s has been through the autoclave. 

The SCB distribution (SCBD) has been extensively studied by fractionation based on compositional difference as well as molecular size. The analysis by cross fractionation, which involves stepwise separation of the molecules on the basis of composition and molecular size, has provided information of inter- and intramolecular SCBD in much detail. The temperature-rising elution fractionation (TREE) method, which separates polymer molecules according to their composition, has been used for HP LDPE it has been found that SCB composition is more or less uniform [24,25]. It can be observed from the appearance of only one melt endotherm peak in the analysis by differential scanning calorimetry (DSC) (Fig. 1) [26]. Wild et al. [27] reported that HP LDPE prepared by tubular reactor exhibits broader SCBD than that prepared by an autoclave reactor. The SCBD can also be varied by changing the polymerization conditions. From the cross fractionation of commercial HP LDPE samples, it has been found that low-MW species generally have more SCBs [13,24]. 

Simulation and application of the ideas for productivity enhancement in an LDPE tubular reactor... 

Van Vliet et al. (2004, 2006) investigated the formation of hot spots and reactor efficiency in various geometrical configurations of a tubular reactor for manufacturing Low-Density Polyethylene (LDPE) by means of the above... 

Van Vliet, E., Derksen, J. J., and Van den Akker, H. E. A., Numerical Study on the Turbulent Reacting Flow in the Injector Region of an LDPE Tubular Reactor . Proceedings of the 12th European Conference on Mixing, Bologna, Italy, pp. 719-726 (2006). 

The LDPE production with tubular reactors (see Section 5.1) requires some sophisticated control valves [45]. The let-down valve (Fig. 4.2-6 B) controls the polymerization reaction via the pressure and temperature by a high-speed hydraulic actuator (9) together with an electronic hydraulic transducer. The position of the valve relative to the stem is determined by a high-resolution electronic positioner (7). The cone-shaped end of the valve stem (2), as well as the shrunk valve seat (3) are made from wear-resistant materials (e.g., sintered tungsten carbide) in order to tolerate the high differential pressure of around 3000 bar during the expansion of the polymer at that location. 

The in-line safety valve [45] as shown in Fig. 4.2-7 is used in LDPE plants during emergency situations in order to depressurize the system by the outlet (2). The valve is directly included in the tubular reactor train (1) in a manner to avoid dead spaces where harmful decomposition of the polymer could take place. The control of the safety valve is effected again by a special... 

The first section of this chapter describes the most important high pressure process run under homogeneous conditions to manufacture Low Density PolyEthylene (LDPE). The radical polymerization of ethylene to LDPE is carried out in tubular reactors or in stirred autoclaves. Tubular reactors exhibit higher capacities than stirred autoclaves. The latter are preferred to produce ethylene copolymers having a higher comonomer content. 

LDPE was occasionally found in 1933 by R.O. Gibson and E.W. Fawcett, when they tried to perform reactions with ethylene [1]. Based on their invention. Imperial Chemicals Ltd (ICI), Great Britain, developed a process with a stirred autoclave in which ethylene was radically polymerized under high pressure [2], Later, BASF AG in Germany designed a tubular reactor to produce LDPE under similar high-pressure conditions [3]. 

Economic data for a LDPE plant equipped with a tubular reactor are given as an example. The industrial unit is described in detail in Chapter 5.1. In order to show the influence of plant capacity the capital and production costs of two units for the production of 100,000 and... 

The advantages known from the production of low-density polyethylene (LDPE) become obvious also when metallocene catalysts are used under high-pressure conditions. The compressed monomer can dissolve the polymer which is formed during polymerization, which means that no additional solvent is required for the polymer. The high-pressure polymerization proceeds with a high rate, which requires a short residence time and small reactor volume. Established technology, with stirred autoclaves as well as tubular reactors, can be applied. 

In the literature many studies on LDPE tubular reactors are found (2-6).All these studies present models of the tubular reactor, able to predict the influence, on monomer conversion and temperature profiles, of selected variables such as initiator concentration and jacket temperature. With the exception of the models of Mullikin, that is an analog computer model of an idealized plug-flow reactor, and of Schoenemann and Thies, for which insufficient details are given, all the other models developed so far appear to have some limitations either in the basic hypotheses or in the fields of application. 

Due to the lack of published data on the special flow field generated in the LDPE tubular reactor by the end pulsing valve, the development of the mathematical model was preceded by a fluiddynamic study, with the aim of evidencing the influence, if any, of the pulsed motion on the axial mixing, the heat transfer coefficient and the pressure drop in the reactor. 

Application The high-pressure Lupotech TS or TM tubular reactor process is used to produce low-density polyethylene (LDPE) homopolymers and EVA copolymers. Single-train capacity of up to 400,000 tpy can be provided. 

Application To produce low-density polyethylene (LDPE) and EVA copolymers by an unique high-pressure clean tubular reactor (CTR) process. Single-line capacities up to 400 mtpy are available. 

Materials and Heat Treatment. The LDPE used, Unifos DFDS 6600, is a high pressure product produced in a tubular reactor. Unifos has reported the LDPE to be free from additives. It had... 

Polyethylene,LDPE, tubular reactor - Lyondell-Basell Polyolefins and LyondellBasell... 

Application To produce low-density polyethylene (LDPE) homopolymers and ethylene vinyl acetate (EVA) copolymers using the high-pressure free radical process. Large-scale tubular reactors with a capacity in the range of 130,000 tpy-425,000 tpy, as well as stirred autoclave reactors with capacity around 125,000 tpy can be used. 

Description A variety of LDPE homopolymers and copolymers can be produced on these large reactors for various applications including films, molding and extrusion coating. The melt index, polymer density and molecular weight distribution (MWD) are controlled with temperature profile, pressure, initiator and comonomer concentration. Autoclave reactors can give narrow or broad MWD, depending on the selected reactor conditions, whereas tubular reactors are typically used to produce narrow MWD polymers. 

LDPE Random branching with either short (average C4) or long (many C) branches dependant on autoclave or tubular reactor t)fpe Many short branches limit crystalUnity and lamella thickness (reduce T ) long branches provide non-Newtonian rheology and melt strength... 

PBE with both short and long branches are prepared from radical polymerization in the traditional high pressure process. These PE are called low density polyethylene (LDPE). A molecular model of a conformation of a typical LDPE is shown in Eig. 3.3. LDPE with different proportions of short and long branches are formed using autoclave or tubular reactors. There are many short branches with average... 

Tubular reactors, see Fig. 3.18(b), are used to make film grade LDPE. The flow through the reactor pipe is turbulent, so there is good mixing in the radial direction however, the blunt velocity profile limits the back mixing that occurs. Free radical initiators are injected into the flow at various spots along the path to cause... 

Chemically, LLDPE can be described as linear polyethylene copolymers with alpha-olefin comonomers in the ethylene chain. They are produced primarily at low pressures and temperatures by the copolymerization of ethylene with various alpha-olefins such as butene, hexane, octane, etc., in the presence of suitable catalysts. Either gas-phase fluidized-bed reactors or liquid-phase solution-process reactors are used. (In contrast, LDPE is produced at very high pressures and temperatures either in autoclaves or tubular reactors.)... 

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