CS196677B1 - Device for vinyl acetate production - Google Patents

Description

(54) Equipment for the production of vinyl acetate

The present invention relates to an apparatus for producing vinyl acetate from acetylene and acetic acid in the vapor phase in the presence of a catalyst.

At present, the production of vinyl acetate from acetylene and acetic acid by a parophasic process is most often carried out in tubular reactors with a fixed catalyst bed, the preheated synthesis mixture consisting of acetic acid vapor and 3-10 times molar amount of acetylene flows through the catalyst bed in the tubes and after reaction most often by two passages to a common manifold for cooling and separation. The number of reactors is usually different, usually even, with at least two at the same time. Thus, the exiting reaction mixture must, after leaving the catalyst bed, pass from the reactor through a parallel pipe with a plurality of elbows to the manifold, where it is mixed with the passages of the other reactors and proceeds to the first cooling stage and further processing. Since it is necessary to work with a large molar excess of acetylene, the resulting reaction exhausts largely contain unreacted acetylene, acetic acid, vinyl acetate and other by-product components in the reactor.

From the point of view of industrial use, the synthesis needs to be carried out at a relatively high temperature level, the vinyl acetate formation reaction itself is strongly exothermic, while the released heat is also consumed to heat the leaving mixture, thereby creating favorable conditions for decomposition or deplagration of acetylene. As a result, the mixture is susceptible to decomposition at any subsequent processing transport, as evidenced by a number of existing plant data and increasing the risk of vinyl acetate production. Extensive research to determine safe working with acetylene and its mixtures does not guarantee a safe way to produce vinyl acetate. The obtained temperature and pressure limits of safe work with acetylene and impurities are dependent on the method of measurement and handling, and to a lesser extent also on the quantity and quality of impurities. It is known that the addition of a gaseous additive to acetylene causes a shift in the boundaries of decomposition, deflagration and detonation towards higher levels. However, this cannot be applied to said reaction system, since the performance of the apparatus drops sharply and the addition of each additional component causes side reactions which are a cause of subsequent processing complications such as separation of the reaction mixture. Other impurities such as catalytic escape, the presence of oxygen and oxygen species, corrosion from equipment corrosion, the possibility of polymerizing acetylene under given conditions and the presence of higher acetylenes, in turn, reduce the temperature of the fire such as pyrophoricity, decomposition etc. '. This is also aided by the highly exothermic subsequent reactions of vinyl acetate. A set of these effects results in a general disruption of the additive effects of admixtures, mainly acetic acid, and therefore a reduction in temperatures and pressures for safe work is required, which is disadvantageous from the point of synthesis itself. It is known that the presence of vinyl acetate in acetylene does not have a favorable effect but, on the contrary, aids in the decomposition of acetylene at lower temperatures, thereby reducing the safety of the manufacturing process. For more details, see Guczalski R. Thermal stability of Zinc acetate catalyst and reagents of vinyl acetate synthesis from Acetylene and Acetic Acid, Rocz. Chem. 48, 10, 1723-30 (1974).

These drawbacks are overcome by the vinyl acetate production apparatus according to the invention, characterized in that the mixer is connected by piping to the inlet tubing of the heat sinks, which are connected by the outlet tubing of the tubing to the pre-heater of the synthesis mixture. The outlet of the preheater is connected by piping to the reactor inlet section. The heat sinks are directly connected to the outlet part of the reactor through the intake inter-tube spaces. The outlet inter-tube spaces of the heat sinks are connected by piping to the collecting piping, which is subsequently connected to the machine technology of vinyl acetate production. This avoids the side and subsequent reactions, all of which hitherto known are exothermic, and their thermal effects add up. In conjunction with the known effects on acetylene transport behavior, this mixture is at the boundary of stability and the slightest concordant effect, such as pressure shock or pressure fluctuations, will cause the mixture to decompose or otherwise decompose, resulting in a rapid temperature rise in outlet pipe and synthesis immediate shutdown is required. Otherwise there is an acute danger of explosion.

In particular, the advantages of the present invention reside in its ease of realization without direct interference with the reactor equipment or subsequent equipment. Nevertheless, it does not require subsequent verification of operation, therefore, due to interference with technology, it does not cause complications in terms of operational safety, but vice versa - it improves it. Furthermore, the possibility of unwanted forms of decomposition of acetylene and, moreover, a heat sink in the circuit according to the invention is avoided, at the same time fulfilling the function of a safety closure, thereby increasing the safety of the entire production and eliminating production losses during forced shutdowns.

An exemplary embodiment of the invention is shown in the accompanying drawing.

Under this illustration, fresh and regenerated acetic acid are fed to mixer 1 where continuous mixing with fresh and recycled acetylene takes place. The resulting mixture is fed through lines 2a, 2b through the heat sink duct space 3a, 3b through lines 4a, 4b to a preheater 5 in which it is preheated to the desired temperature and leads to the inlet part 8 of the reactor 7. After passing through the catalyst bed. the synthesis gas flows through the reactor outlet portions 8a, 8b to the inlet inter-tube portions of the heat sinks 3a, 3b, which are directly connected to the reactor outlet portions 8a, 8b

7. The cooled synthesis gas exits from the outlet portion of the inter-tubular spaces of the heat sinks 3a, 3b and passes through the pipes 9a, 9b to the manifold 10, for further processing by known methods.

SUBJECT

Claims (2)

such as pyrophoric, decomposition, etc. This is also aided by highly exothermic subsequent reactions of vinyl acetate. The set of these effects results in an overall impairment of the stabilizing effects of the admixtures, mainly acetic acid, and thus the need to reduce the temperatures and pressures for a safe work, which is disadvantageous from the hill of the synthesis itself. It is known that the presence of vinyl acetate in acetylene does not favor, but rather helps to decompose acetylene at lower temperatures, thereby reducing the safety of the manufacturing process. More details are given in Guczalski®. Thermal stability of Zinc acetate catalyst and reagents of Winylacetate synthesis from Acetyleneand Acetic Acid, Rocz. Chem. 48, 10, 1723-30 (1974). The above drawbacks are eliminated by the device for producing vinyl acetate according to the invention, which consists in that the mixer is a pipe connected to the inlet pipe spaces of the heat sink, which are connected through the outlet pipe spaces through the pipes on the preheater of the synthesis mixture. The output of the preheater is connected via a duct to the reactor inlet. They discharge the heat through the inlet inter-duct space directly associated with the outlet portion of the reactor. The outlet inter-duct spaces of the drainage duct are connected via pipelines to a manifold, which is subsequently connected to the machine-technical device for the production of vinyl acetate. This avoids more reactive and subsequent reactions, all of which are known to be exothermic, their thermal effects added together. In conjunction with the known effects on the acetylene behavior of the trans-porate, this mixture is found at the stability boundary and the least consistent effect, for example, a pressure burst, or pressure fluctuations, brings the mixture to a de-composition or other form of decomposition, resulting in a rapid temperature rise in output pipe and synthesis it is necessary to immediately shut down. Otherwise, the acute danger is the possibility of an explosion. The advantages of the present invention lie in particular in its simple implementation without the direct intervention of the reactor equipment and subsequent equipment. However, it does not require subsequent verification of the operation, as a result of interfering with the technology, it does not cause complications from the safety of operation, but on the contrary - it improves the possibility of showing undesirable forms of acetylene decomposition and, moreover, the heat in the connection according to the invention. safety closure, thereby increasing the safety of the entire production and avoiding production losses in forced shutdowns. An exemplary embodiment of the invention is shown in the accompanying drawing. According to the drawing, fresh and reclaimed acetic acid is fed to the mixer 1, where complete mixing with fresh and recycled acetylene occurs. The resulting mixture is passed through the pipes 2a, 2b through the tubular space of the heat sinks 3a, 3b through the pipes 4a, 4b to the preheater 5, in which it is preheated to the desired temperature and fed to the inlet part 6 of the reactor 7. After the catalyst is passed through its own son the synthesis gas flows through the outlet portions 8a, 8b of the reactor 7 to the inlet intermediate pipe portions 3a, 3b which are directly connected to the reactor outlet portions 8a, 8b 7. The cooled synthesis gas is discharged from the outlet portion of the intermediate ducts of the heat sinks 3a, 3b and is fed through the ducts 9a, 9b to the collection duct 10 through which it can be further processed by known methods. PREDM ET A device for the production of vinylacetate of acetylene and acetic acid in the vapor phase in the presence of a catalyst, consisting of a mixer, a heat sink, a preheater, a reactor and connecting pipes, characterized in that the mixer (1) is a conduit (2a, 2b) connected to the inlet pipe spaces of the heat sinks (3a, 3b), which are connected by the outlet pipe spaces - to the pipes (4a, 4b) to the preheater (5) and to the outlet therefrom is connected to the inlet (6) of the reactor (7) and the inlet intermediate ducts are heat dissipations (3a, 3b) directly connected to the outlet portions (8a, 8b) of the reactor (7), being connected to the manifold (10) via ducts (9a, 9b).