US 12,065,518 B2
Methods of controlling shutdown of reactor systems
Paul J. Clymans, Kapelle-Op-Den-Bos (BE); Jefferson P. Galliano, Singapore (SG); Philippe A. P. D'Hooghe, Merelbeke (BE); Cindy Dewitte, Puurs-Sint-Amands (BE); and Henri A. Lammens, Antwerp (BE)
Assigned to ExxonMobil Chemical Patents Inc., Baytown, TX (US)
Appl. No. 17/309,175
Filed by ExxonMobil Chemical Patents Inc., Baytown, TX (US)
PCT Filed Nov. 13, 2019, PCT No. PCT/US2019/061227
§ 371(c)(1), (2) Date May 3, 2021,
PCT Pub. No. WO2020/102388, PCT Pub. Date May 22, 2020.
Claims priority of provisional application 62/760,299, filed on Nov. 13, 2018.
Prior Publication US 2022/0025075 A1, Jan. 27, 2022
Int. Cl. C08F 2/01 (2006.01); B01J 3/04 (2006.01); B01J 19/00 (2006.01); C08F 110/02 (2006.01); C08F 210/02 (2006.01); C08F 218/08 (2006.01)
CPC C08F 2/01 (2013.01) [B01J 3/042 (2013.01); B01J 19/002 (2013.01); C08F 110/02 (2013.01); B01J 2219/00162 (2013.01); B01J 2219/00236 (2013.01); B01J 2219/00259 (2013.01); B01J 2219/0027 (2013.01); C08F 218/08 (2013.01); C08F 2400/04 (2021.01)] 15 Claims
OG exemplary drawing
 
1. A method of controlling shutdown of a polyethylene reactor system comprising:
providing a polyethylene reactor system comprising a suction heater and drum 150, a primary compressor 152, a secondary compressor 154, a reactor 156, a high pressure let down valve (HPLDV) 130, a high-pressure separator 158, and a high-pressure recycle gas system 160;
wherein the reactor 156 operates at a pressure of about 3000 bar-g;
experiencing a partial or complete shutdown of secondary compressor 154;
opening the HPLDV 130 to a pre-set open position until a reactor 156 pressure reduces to either a pre-set reduced pressure limit or until a slope of the reactor gas density to reactor pressure exceeds 0.15;
after reactor 156 pressure reduces to either the pre-set reduced pressure limit or after the slope of the reactor gas density to reactor pressure exceeds 0.15:
controlling the HPLDV 130 to control the pressure in line 114 that connects the high-pressure separator 158 outlet to an inlet of the high-pressure recycle gas system 160 to a pressure set point that is approximately 10 bar-g less than the pressure that would cause the high-pressure recycle gas system 160 to vent to avoid overpressure;
controlling a flow in first compressor recycled ethylene line 132 that recycles ethylene from a primary compressor outset to an ethylene feed line 100 to the suction heater and drum 150 using valve 134;
allowing a flow of ethylene leaving the high-pressure recycle gas system 160 to travel through first compressor recycled ethylene line 132 that recycles ethylene from the primary compressor outset to the ethylene feed line 100 to the suction heater and drum 150;
removing ethylene from purge recycled ethylene line 122 to a liquid storage facility and optionally also removing ethylene from makeup ethylene line 102 to an ethylene header.