NAO Reactor Operation

• Five reactors work in parallel to meet design production rates, with 90% on-line availability.
• All five reactors are online approximately 30% of the time.
• The 10% non-availability is due to the reactor being taken off-line for solvent washing.
• Reactors are solvent washed about once a month to remove waxy polymer buildup, ensure temperature contro, and maintain stable reactor operation.
• Four of the five reactor systems are typically in service, while one is down for solvent washing.
• Compressed ethylene feed and aluminum alkyl catalyst (TEA) flow to each of the reactors to react and form NAO products.
• The reactor section aims to produce NAO products with high alpha olefin content and vinylidenes within specifications.
• Proper control of reactor pressure, temperature, ethylene feed rate and purity, and catalyst feed rate is essential.
• Reactor operation must avoid upsets that could lead to temperature excursions.
• An ethylene purge constantly flows through the inlets of the PSVs and critical transmitters of all reactors.
• The ethylene purge gas passes through Coalescers (CS-202-1/2/3/4/5) for oil removal.
• Pre-filters (FI-202-1/2/3/4/5) removes contaminants, before being routed to the reactors.
• Effluent exits each reactor and is flashed across a control valve.
• The reactors' effluent is routed to the tube side of Reactor Effluent Coolers (E-201-205) and is cooled by cooling water on the shell side.
• Cooling the effluent streams stops the undesirable reactions.
• After cooling, the effluent streams combine into one common header.

R-201-205 (Reactors)

• Horizontal multi-tube reactors, consisting of 216 tubes.
• The first four tubes preheat the ethylene feed, catalyst injection at the fifth tube.
• Conversion occurs in the remaining 211 tubes producing even-carbon, straight-chained Normal Alpha Olefins.
• The process is exothermic, with the heat being controlled by steam production.
• Reactors shall not be operated without PSV purge flows.
• Catalyst propagating into the relief valve riser piping can cause overheating, decomposition, and catastrophic piping failure.

P-201-205 (Catalyst Pumps)

• Oilgear/Petrodyne Catalyst Injection Pumps use hydraulic pressure to drive a piston back and forth in a cylinder.
• Reciprocating piston types with horizontally opposed plungers powered by variable volume hydraulic pumping systems.
• Pistons are held in place by rigid housings made of closely machined steel castings which align the plungers in the fluid cylinder.
• The hydraulic pressure which drives the pistons, is provided by variable volume pumps manufactured by the Oilgear Hydura Division.
• An axial piston pump has a rotating cylinder with a series of pistons which move in or out of the cylinder as the cylinder rotates.
• The amount of volume produced by the pump is determined by the position of the pump swashplate.
• Purpose: inject a precise amount of dilute catalyst (5 wt% TEA) to R-201-205 at the fifth tubes.

P-200 (Catalyst Pump)

• Bran+Luebbe diaphragm style positive displacement pump with an adjustable pump stroke as well as a variable frequency drive to control pump speed.
• Purpose: inject a precise amount of dilute catalyst (5 wt% TEA) to R-205 at the fifth tube.

E-201-205 (Reactor Effluent Coolers)

• Shell and tube, U-tube type heat exchangers that cool the reactor effluent on the tube side with cooling water on the shell side.
• Purpose: cool the reactor effluent and stop the undesirable formation of vinylidenes.

CS-202-1,2,3,4,5 (Coalescers)

• A device that separates an emulsion into the individual components, whether liquid/liquid, vapor/liquid or multi-phase.
• Mechanical coalescing involves some type of media such as stainless mesh or filter element, inserted into a vessel and passing the emulsion through this mesh.
• Small droplets of the heavier liquid will cling to the mesh/element and form larger droplets, which will eventually become heavy enough to fall to the bottom of the vessel where they will stay separated and can be withdrawn.
• The same principle works for removing liquid from a gas that is passed over a mesh/filter element.
• Installed on the ethylene purge lines to each reactor to remove residual oil from the ethylene prior to being routed to the reactors.

FI-202-1,2,3,4,5 (Pre-filters)

• Installed on the ethylene purge lines to each reactor to remove contaminants from the ethylene prior to being routed to the reactors.