Method and apparatus for controlling polyolefin reactor temperature

Abstract

Methods and apparatus for controlling polyolefin reactor temperature. In one embodiment, a simulation model is constructed for improving control of polymerization temperature in a polyethylene loop slurry reactor. The model is used to design the reactor coolant system to capacity and to improve tuning of system controllers, such as the reactor temperature controller and coolant temperature controller. A coolant control valve is sized having a bilinear flow characteristic which improves Cv reproducibility at low coolant flow rates and thus improves reactor temperature control.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates generally to the polymerization of polyolefins and, more specifically, to the use of a coolant system and simulation model to control temperature in a polyethylene loop slurry reactor. [0003] 2. Description of the Related Art [0004] This section is intended to introduce the reader to aspects of art that may be related to aspects of the present invention, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. [0005] As chemical and petrochemical technologies have advanced, the products of these technologies have become increasingly prevalent in society. In particular, as techniques for bonding simple ...

AI Technical Summary

Benefits of technology

The present invention relates to a method for controlling the temperature in a polyolefin loop slurry reactor, specifically for the production of polyethylene. The invention involves the use of a coolant system and a simulation model to control the reactor temperature. The technical effects of the invention include improved reactor temperature control, reduced coolant system equipment costs, increased reactor stability, and improved polyethylene production quality.

Problems solved by technology

Problems with coolant control valve sizing and with tuning of the primary and slave controllers have caused poor temperature control of the polymerization.

These problems cause the coolant system to remove too little heat or too much heat from the reactor.

Poor temperature control in the reactor increases the cost to manufacture polyethylene.

In particular, poor temperature control in the reactor results in a wider design basis for coolant system equipment and thus increases equipment costs.

Furthermore, swings in reactor temperature impact reactor stability and can lead to a reactor foul and / or unplanned shutdown.

Additionally, polymerization temperature affects the properties of the polyethylene and thus poor control of reactor temperature cause off-spec production of polyethylene.

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