JPS59207909A - Reciprocatory compressor available under high pressure and use for polymerization of ethylene-alpha-olefin polymerization - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reciprocating compressor for use under extremely high pressures and its use in the polymerization process of ethylene and alpha-olefins.

The present invention aims to solve the technical problems associated with compressing fluids at compression pressures of 150 bar or more that meet at least one of the following three conditions: Here, the above three conditions are i. The fluid contains a trace amount of abrasive particles; 11. The fluid is not self-lubricating and no lubricant is added from the outside; iii. The fluid is not self-lubricating and is involved in processes where lubricant is added externally, but in some cases it is a lubricant medium.

The fluid relevant to the subject matter of the invention may be in liquid or gaseous state. Also, the temperature is in the range -30-200°C for all stages of the compressor, and the fluid contains a wide variety of chemicals such as helium, ammonia, ethylene, alpha-olefins, hydrogen, and saturated It may be a mixture with at least one compound selected from the group consisting of hydrocarbons, for example propane or butane.

Compression of a fluid under a compression pressure of 150 bar or more generally involves one or more steps, reciprocating,
As a result, each cylinder has on the one hand a plunger or cylinder jacket and on the other hand at least one stationary seal in several parts (in the case of a plunger) or at least one movable segment fixed to the piston (in the case of a cylinder jacket), etc. In the case of seals, the dynamic seal is achieved between the seal or seals and the plunger; in the case of segments, the seal is between the cylinder jacket and at least one segment. achieved between.

If the fluid to be compressed does not correspond to any of the three conditions mentioned above, in particular if it is self-lubricating and/or does not contain traces of abrasive particles, and/or the dynamic sealing If the surfaces in contact with the components are lubricated, the compressor can run for up to 70 minutes without disturbance.
The compressor operates satisfactorily for thousands of hours, up to 00 hours, and requires no special attention to the materials that make up the different parts of the compressor. For example, when pressurizing ethylene or mixtures of ethylene and polar comonomers to compression pressures in the range 150 to 3000 bar, in particular French Patent No. 1,58
4.529, 2.025.887, 2.0
99.267 and 2.313.399, in which the plunger or cylinder jacket is treated at high temperatures in the presence of a free-radical initiator. It is made of steel or cast, or is made of a substance such as carbide of metal such as tungsten, and the airtight element is made of 9% tin, 0%
．． It is common to use reciprocating compressors, such as those made of bronze, such as bronze UB9P, which consists of 3-1% phosphorous and the balance copper. This is based on the fact that the ethylene flags to be compressed do not contain traces of abrasive particles.

Conversely, if the fluid to be compressed corresponds to at least one of the three conditions mentioned above, a reciprocating compressor whose parts are constructed of commonly used materials will most likely operate satisfactorily. i.e., it operates only for a limited period of time, for example several tens of hours, without disturbance. The tens of hours corresponds to the absence of lubrication and/or the presence of abrasive particles in the fluid. An analysis of the causes of this unsatisfactory behavior was carried out in particular by examining the surface of the sealing element, for example with an optical microscope and an electron microscope. Extremely rapid surface wear leads to unavoidable wear of the compressor sealing elements. The present invention aims to solve the technical problems that arise in this way.

A first object of the present invention is to provide a significantly high-pressure casting body comprising at least one plunger or cylinder jacket and at least one hermetic element made of one material selected from the group consisting of steel and tungsten carbide. The object of the present invention is to provide a reciprocating compressor for use with It is made of a composite material blended with a polymer selected from fluoroethylene, polyimide and polyimide-amide or a graphite-silver fritting compound.

Among the bronzes useful for the compressor hermetic element of the present invention, mention may be made in particular of the bronze UIE9P.

Titanium-based alloys useful for the hermetic element of the compressor of the present invention include alloys of titanium and silver, such as alloys containing 94% by weight titanium and 6% by weight silver. . Polymers useful for compressor sealing elements of the present invention may also optionally be filled with graphite and/or glass fibers;
It is likewise possible to reinforce it with bronze fabric.

The bonding of the two types of composite materials used for the compressor sealing element of the present invention can be carried out according to the two methods described below. According to the first method, the bonding is achieved by a bonding system in the form of adhesive bonding. A preferred adhesive is
A peel resistance of KN/m or more can be provided. According to a second method, the bond is achieved by a bonding system in the form of a vacuum solder, for example with a gold-germanium alloy or also with silver. This bonding is advantageous depending on the method used depending on the particular geometry of the composite, which consists of inserting a polymer or graphite-silver fritted compound into a metal alloy ring.

The compressor of the invention operates satisfactorily, ie without any disturbance, for a period of 1000 hours or more under the following conditions: That is, (a) the compressed fluid, i.e. liquid or gas, is -30
(b) the compression pressure of the fluid is 150 bar or more; (C) the reciprocating motion of the compressor is relatively low depending on the compression pressure; (d) the compressed fluid contains traces of abrasive particles in an amount corresponding to a coefficient of friction of the order of 0.5; and (e) The compressed fluid is not self-lubricating and cannot be supplied with external lubricant.

The reciprocating compressor according to the present invention has various applications in the chemical industry, such as polymerization of ethylene under high pressure or polymerization of ethylene and α
- Used for copolymerization with olefins. In fact, according to French patent no.
It is known to be carried out in the presence of a Ziegler-type catalyst system at temperatures in the range of . A large number of catalyst systems of this type are used for the polymerization of ethylene at high pressures and temperatures as well as for the polymerization of ethylene and α
- It is known to be employed in copolymerization with olefins. These catalyst systems generally include at least one transition metal halide and at least one selected from hydrides and organometallic compounds of metals from Groups 1 to 2 of the Periodic Table of the Elements.
Contains a seed activator. Among the large number of useful transition metal halides, π-allyl or benzyl complexes of chromium, zirconium and titanium, trichloride of vanadium and titanium (which in some cases
eutectic with aluminum chloride in the form TiCl3/38ICl3), optionally supported on a carrier containing, for example, a halide, monohalide or hydrohalide of magnesium. I can do it.

All these compounds can also be used in the presence of complexing agents such as lower alcohols, metal alcoholades, alkyl silicates, aryl or alkyl siloxanes, ethers or amines. Among the useful activators, mention may be made in particular of trialkylaluminums, halogenodialkylaluminums and alkylsiloxanes.

In such polymerization or copolymerization processes, the mixture from the reactor is sent to a separator operating under a pressure of 50 to 500 bar, where the polymer and unreacted monomers are separated, and then the monomers from the separator are It is compressed to reaction pressure and sent to the reactor. It has been found that a significant amount of catalyst residues, especially lower polymers containing aluminum compounds or other reducing agent compounds, are entrained in the flux of unreacted polymer to be compacted. When the compressor operates, 1
A portion of the lower polymers, present as particles with a particle size in the range of ~250 microns, can compress the content of catalyst residues in the fluid to be recycled to more than 0.5 ppm, causing wear of the sealing element of the compressor. This is one of the causes.

A second object of the invention is to provide a process for the polymerization of ethylene which is carried out in a reactor at a pressure of more than 200 bar and at a temperature of more than 170° C. in the presence of a Ziegler type catalyst system. and the mixture from the reactor is 50-5
The polymer is sent to a separator under pressure in the range of 00 bar, where the polymer is separated from unreacted monomers, and the ethylene from the separator is pressurized to the pressure of the reactor and sent there. The method of the present invention comprises pressurizing ethylene from the separator.
It is characterized in that it is carried out by a compressor according to the invention as already described. Such a method of the present invention has high reliability because the compressor operates sufficiently.

The process of the invention can carry out the polymerization of ethylene in the presence of 1 to 50% by weight of an inert hydrocarbon, such as propane or butane, and/or in the presence of up to 2 mol% hydrogen. The process of the invention can be carried out continuously and can use autoclaves, tubular reactors, and various types of reactors. Each of the reactors may have one or more reaction zones. The invention can also be applied to the copolymerization of ethylene with alpha-olefins such as propylene and 1-butene. Furthermore, it can be applied to the formation of terpolymers of ethylene, alpha-olefins such as propylene, and non-conjugated diolefins.

Patent applicant: Société Mic de Charbonage varnish, ah.

Representative Patent Attorney Masahiko Arai

Claims (1)

Claims: (1) used under extremely high pressure, comprising at least one cast body, a plunger or cylinder jacket made of a material selected from steel and tungsten carbide, and at least one hermetic element; A reciprocating compressor, wherein the hermetic element comprises at least one
Made from a composite material blended with a metal alloy selected from bronze and titanium-based alloys and at least one polymer selected from polytetrafluoroethylene, polyimide and polyimide-amide or a graphite-silver fritted compound. The above-mentioned reciprocating compressor is characterized in that: (2) The reciprocating compressor according to claim 1, wherein the polymer is filled with graphite and/or glass fiber. (3) A reciprocating compressor according to claim 1 or 2, characterized in that the polymer is reinforced with bronze fabric. (4) The metal alloy and polymer or graphite-silver fritted compound of the composite are bonded by a bonding system selected from adhesives and vacuum welding. Any one
Reciprocating compressor as described in Section. (5) The reciprocation according to claim 4, characterized in that the metal alloy and polymer or graphite-silver fritted compound of the composite is reinforced by inserting a polymer into a ring of metal alloy. compressor. (6) The reciprocating compressor according to any one of claims 1 to 5 is used for pressurizing a fluid to a compression pressure of 150 bar or more. How to use the machine. (7) the temperature of the fluid is -30°C for all stages of the compressor;
7. The use according to claim 6, characterized in that the temperature is in the range of ~+200<0>C. (8) A method according to claim 6 or 7, characterized in that the fluid contains traces of abrasive particles. (9) The use according to any one of claims 6 to 8, wherein the fluid is not self-lubricating and is involved in a process in which no lubricant is added from the outside. Law. Q[) Claim 6, characterized in that the fluid is not self-lubricating and is involved in the step of adding a lubricant from the outside, but can serve as a medium for the lubricant.
9. The method of use according to any one of items 9 to 9. (11) The fluid of claims 6 to 10 is characterized in that the fluid is ethylene or a mixture of ethylene and at least one compound selected from the group consisting of α-olefins, hydrogen, and saturated hydrocarbons. The method of use described in any one of the paragraphs. (12> Under pressure of 200 bar or more, and 170 bar
In the presence of a Ziegler-type catalyst system at temperatures above ℃,
carried out in a reactor, and the mixture from the reactor is 50 to 50
The polymer is fed to a separator under pressure in the range of 0 bar, in which the polymer and unreacted ethylene are separated, and the ethylene from the separator is injected up to the pressure of the reactor and reacted. ethylene is recycled to the separator and the ethylene from the separator is at least 0.
．． 12. Use according to claim 11, characterized in that the compressor is used in an ethylene polymerization process containing 5 ppm of residues of the catalyst system.