Polymerization process with a partial shutdown phase
AssigneeBasell Polyolefine GmbH
InventorsErich NEUMANN, Sven WOLFRAM, Christoph WOLF, Juergen MOHRBUTTER, Dieter LITTMANN
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Abstract
A process for polymerizing ethylene to obtain an ethylene-based polymer in a plant, wherein the plant includes a reactor in fluid communication with a recycle connection, wherein the process includes a polymerization phase, a partial shutdown phase, and the steps of reducing the pressure in the reactor for entering into the partial shutdown phase from the polymerization phase; and increasing the pressure in the reactor for exiting from the partial shutdown phase and re-entering the polymerization phase.
Claims20
A process for polymerizing ethylene, and optionally one or more comonomers, to obtain an ethylene-based polymer in a plant having a polymerization reactor, a reactor inlet side, a reactor outlet side, a recycle connection, a product output, and a flow of fluid from the reactor outlet side into the recycle connection and from the recycle connection to the reactor inlet side, comprising the steps of:
- i. reacting ethylene, and optionally one or more comonomers, to obtain the ethylene-based polymer at an operating pressure in the reactor pr1 and an operating pressure in the recycle connection pc1 during a polymerization phase;
- ii. reducing the pressure in the reactor from the pressure of pr1 to a pressure of pr2 by increasing the flow rate of fluid from the reactor outlet side of the plant into the recycle connection, wherein the relation of pr1 and pr2 is pr2≤0.85*pr1 for entering into a partial shutdown phase;
- and
- iii. increasing the pressure in the reactor from the pressure of pr2 to a pressure of pr3, wherein the relation of pr2 and pr3 is pr3≥1.1*pr2 for exiting from the partial shutdown phase and re-entering the polymerization phase
- wherein (a) the polymerization reactor has a reactor inlet and a reactor outlet, (b) the reactor inlet side is located upstream of the reactor inlet, (c) the reactor outlet side is located downstream of the reactor outlet, and (d) the recycle connection has an inlet in fluid communication with the reactor outlet side of the plant and an outlet in fluid communication with the reactor inlet side of the plant.
A plant for polymerization comprising:
- A. a reactor having a reactor inlet and a reactor outlet;
- B. a recycle connection positioned in fluid communication between the reactor outlet and the reactor inlet;
- and
- C. a valve in fluid communication with the recycle connection or a component situated between the reactor outlet and the inlet of the recycle connection, and when being in an open position, the valve provides fluid communication to a receiver;
- wherein the valve is configured to move to an open position as the pressure in the recycle connection exceeds a set pressure.
A process for polymerizing ethylene, and optionally one or more comonomers, to obtain an ethylene-based polymer in a plant having a polymerization reactor, a reactor inlet side, a reactor outlet side, a recycle, a product output, and a flow of fluid from the reactor outlet side into the recycle connection and from the recycle connection to the reactor inlet side, comprising the steps of
- i. reacting ethylene, and optionally one or more comonomers, to obtain the ethylene-based polymer at an operating pressure in the reactor pr1 and an operating pressure in the recycle connection pc1-during the polymerization phase;
- ii. reducing the pressure in the reactor from the pressure of pr1 to a pressure of pr2 by increasing the flow rate of fluid from the reactor outlet side of the plant into the recycle connection, wherein the relation of pr1 and pr2 is pr2≤0.85*pr1 for entering into the partial shutdown phase;
- and
- iii. increasing the pressure in the reactor from the pressure of pr2 to a pressure of pr3, wherein the relation of pr2 and pr3 is pr3≥1.1*pr2 for exiting from the partial shutdown phase and re-entering the polymerization phase;
- and
- wherein
- (a) the polymerization reactor has a reactor inlet and a reactor outlet,
- (b) the reactor inlet side is located upstream of the reactor inlet,
- (c) the reactor outlet side is located downstream of the reactor outlet,
- (d) the recycle connection has an inlet in fluid communication with the reactor outlet side of the plant and an outlet in fluid communication with the reactor inlet side of the plant,
- (e) a valve, being located in the recycle connection, or in a component situated in fluid communication between the reactor outlet side and the inlet of the recycle connection, wherein the valve has a closed position and an open position,
- (f) a receiver for receiving fluid from the recycle connection through the valve when the valve is in the open position, and
- the valve moves from the closed position to the open position as the pressure in the recycle connection exceeds a set pressure pc2, wherein the relation of pc1 and pc2 is pc1<pc2≤1.5*pc1;
- and
- the valve moves from the open position to the closed position as the pressure in the recycle connection decreases below a reset pressure pc3, wherein the relation of pc1 and pc3 is 0.7*pc1<pc3≤pc1, and
- (g) a compressor, being located in fluid communication between the outlet of the recycle connection and the reactor inlet.
Dependencies are inferred from the claim text.