Document 0Qe6JLa1zBO51NDNyYVvNOBb
Modified Furnace Operations Problems and Experiences
n
o h
oa
mo'-i
a> o
-i ^
Chris Reed July 15, 1991
SIMPLIFIED (SELAS) C.G, FURNACE AT LHC 3 MODIFIED
FURNMQD 1/2/91
WASTE HEAT
DUCT
6 DUCT SAHPCa ISOLATION
STACK NEW FURNACE SIMPLIFIED DIAGRAM
INSIDE
0UTJ1CC
OUTSIDE
DO A 0 3 6 1 7 6
C O N F ID E N T IA L .
fCVfURN
4/4/*l
Modified Furnace Operations
Problems Runtimes Less Than Predicted Instrumentation Reliability Coil Outlet Temperature Spreads Feed Rates Different From Predicted
CJR:7/15/91
DO A 0 3 6 1 .7 7
CONFTOE-NTTAl.
Furnace Runtimes
Inadequate Furnace Decoking - Higher Flow Rates -- Longer Decoke Times - C02 Sampling for Completion
DMS Injection Problems - Use on All Feed Types - One Injection Point
CJR:7/15/91
Modified Furnace Runtimes
Average Run Length (Days) 80
60
4-0
20
0
Propane Naphtha Ethane
r> oo
o^
?P
sM0
CJR:7/15/91
Propane
Feed Type Naphtha
Ethane
Instrumentation
Venturi Pressure Ratios - Trouble Getting Good Readings - Plugging Made System Unreliable - Nitrogen Purge Added
CJR:7/15/91
Coil Outlet Temperatures
COT Spread Increases Through Run
COT Spread Not Reduced by Decoke
Possible Causes Include - Uneven Flow Distribution
-- Uneven Coking
-- Instrumentation Problems
- Uneven Heating of Coils
ro> a
2: o
zT-H>*
2 h
I> UcOr)\
CJR:7/15/91
--I>i CO
Coil Outlet Temperature Spreads
Coil Outlet Temperature
oo o
zT] o
m^a
x>
o
HZ CyJ-
Xr~> \0>5
CJR:7/15/91
Max COT ------- Min COT
Modified Furnace Feed Rates
Propane Rates Below Design Values Naphtha Rates Above Design Values Often Constrained By Fuel Gas
oo
-2~Hn
o
1>
2----2'O>lifl C>oJ CJR:7/15/91
Modified Furnace Feed Rates
Average Feed Rate (kg/hr) (Thousands) 24
23
22 21
20
Propane Naphtha
CJR:7/15/91
Feed Type
Propane
Naphtha
Future Plans
Venturi Replacement -- Better Flow Distribution - More Stability at Low Rates - No Longer "End of Run" Criteria
Skin Thermocouples on Coil Outlets Oxygen Control Load Swing Furnace
CJR:7/15/91
Future Plans
Burner Replacement -- Lower NOx Formation - Less Impingement on Tubes - More Even Heat Distribution - Less Susceptible to Plugging
Control of DMS Injection
Mod 5 Control of Furnaces
o
oo
LT o
o
-I a
]>
1
aa
CJR:7/15/91