Abstract: The present disclosure provides an apparatus for preparing oligomer including: a reactor; a gas-liquid separator; a solvent transfer line; a second transfer line; a first spray nozzle unit; and a second spray nozzle unit. The apparatus is capable of improving stability of the entire process by including a first spray nozzle unit and a second spray nozzle unit in a reactor and thus preventing by-products containing polymer substances such as C20+ from being entrained with a desired product during a reaction.

Abstract: The present disclosure provides a reactor cleaning apparatus including: a fixing part having a partial region inserted into a hole formed in an upper portion of a reactor to be coupled to the reactor and fixing a pipe; the pipe inserted into a hole formed in the fixing part, protruding downward from the fixing part, and having a length adjustable in a vertical direction; a spray nozzle provided at a lower end of the pipe; and a screener provided on a lower side surface of the pipe, and a reactor cleaning method using the same.

Abstract: Provided is an apparatus for preparing oligomer including: a reactor for carrying out oligomerization reaction by supplying a monomer stream and a solvent stream; and line 1 and line 2 which are separately provided in a lower side of the reactor, wherein line 1 includes a first level control valve and line 2 includes a second level control valve, and the reactor is periodically alternately operated in first operation mode and second operation mode, thereby switching a pipe through which the product is discharged, so that a plugging phenomenon of the pipe through which the product is discharged and the valve can be prevented.