US 10,377,681 B2Granted

Use of an advanced multivariable controller to control alphabutol units

AssigneeAxens

InventorsJean-Marc Bader, Damien Maintenant

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Abstract

The present invention describes a control system for units for the production of 1-butene by the oligomerization of ethylene in the presence of a homogeneous catalyst, in the liquid phase and at the bubble point, which uses a multivariable predictive controller and provides the units with better stability.

Claims7

Dependent claims

A method for advanced process control (APC) of an ethylene oligomerization unit having a reactor, a catalyst recycling loop or loops and a heat exchanger or exchangers for the catalyst recycling loop or loops, comprising:

oligomerizing an ethylene feed flow to 1-butene in the reactor operated in liquid phase and at bubble point and in the presence of a homogeneous catalyst having two components, while controlling oligomerizing target parameters simultaneously and continuously by adjusting action variables, wherein the two components of the catalyst comprise a first component (LC) comprising titanium or chromium and a second component (T2) comprising aluminum,
wherein the target parameters are production of 1-butene (Dprod), reactor pressure (Preac) and reactor temperature (Treac), and the action variables are ethylene feed flow rate (DCh), flow rate of each of the components of the catalyst (T2 and LC) and flow rate of cooling liquid supplied to the exchanger or exchangers of the catalyst recycling loop or loops;
and
wherein a multivariable controller (termed the APC controller) carries out the method for advanced process control (APC) including performing the following three actions:
controlling the reactor pressure (Preac) by varying the flow rate of each of the two catalyst components and varying the feed flow rate in order to compensate for the effects of reactor pressure on the conversion which affects the production,
controlling the production (Dprod) by varying the feed flow rate and the flow rate of each of the two catalyst components in order to compensate for the effects on the reactor pressure,
controlling the reactor temperature (Treac) by acting on the flow rate of the cooling liquid which is supplied to the exchanger or exchangers of the catalyst recycling loop or loops,
wherein the flow rates of the components of the catalyst, T2 and LC, are varied within a range such that the ratio (T2/LC) is kept between 1.5 and 3 moles/moles;
the APC controller being installed in a computer which is connected to the system controlling the process in the oligomerization unit, said computer carrying out the following operations:
recovering signals for the action variables and the target variables,
generating new setpoints for the action variables, and
sending the new setpoints to the APC controller.

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Dependencies are inferred from the claim text.

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Abstract

oligomerizing an ethylene feed flow to 1-butene in the reactor operated in liquid phase and at bubble point and in the presence of a homogeneous catalyst having two components, while controlling oligomerizing target parameters simultaneously and continuously by adjusting action variables, wherein the two components of the catalyst comprise a first component (LC) comprising titanium or chromium and a second component (T2) comprising aluminum,
wherein the target parameters are production of 1-butene (Dprod), reactor pressure (Preac) and reactor temperature (Treac), and the action variables are ethylene feed flow rate (DCh), flow rate of each of the components of the catalyst (T2 and LC) and flow rate of cooling liquid supplied to the exchanger or exchangers of the catalyst recycling loop or loops;
and
wherein a multivariable controller (termed the APC controller) carries out the method for advanced process control (APC) including performing the following three actions:
controlling the reactor pressure (Preac) by varying the flow rate of each of the two catalyst components and varying the feed flow rate in order to compensate for the effects of reactor pressure on the conversion which affects the production,
controlling the production (Dprod) by varying the feed flow rate and the flow rate of each of the two catalyst components in order to compensate for the effects on the reactor pressure,
controlling the reactor temperature (Treac) by acting on the flow rate of the cooling liquid which is supplied to the exchanger or exchangers of the catalyst recycling loop or loops,
wherein the flow rates of the components of the catalyst, T2 and LC, are varied within a range such that the ratio (T2/LC) is kept between 1.5 and 3 moles/moles;
the APC controller being installed in a computer which is connected to the system controlling the process in the oligomerization unit, said computer carrying out the following operations:
recovering signals for the action variables and the target variables,
generating new setpoints for the action variables, and
sending the new setpoints to the APC controller.

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