Plantilla de excel para aplicar la metodología HazopDescripción completa
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Example on how to conduct HAZOP study on distillation columnFull description
hazop silDescripción completa
hazopFull description
Study Node: Oxidation Reactor Process : Oxidation of p-xylene to Terephthalic Acid
Hazop
HAZOP Exercise
[Type text]
Guide Word
Deviation
NONE
NO FLOW
Causes (1) Blockage in line
(2) Solid DEA in tank (3) Pump fails
(4) Pressure in line = pressure in reactor
Consequences
Safeguards
Action Required
- Loss of flow to reactor, no reaction due to control response. - DEA solidifies in line. - Possible line rupture due to pump overpressure. - Pump motor burn out, possible fire.
- Line is electrically traced to maintain DEA as liquid. - Pump is tripped by pressure in line. -
(a) Temperature indicator and controller needed on line to control tracing. (b) Design pipes to take maximum pump pressure. (c) Heat tank using jacket and/or coil Covered by (a), (b), (c)
As for (1) - Cavitation in pump As for (1) - DEA stays in storage tank - Backflow through valve V-8 - Heat exchanger overheat, line expansion As for (1) and (3)
- Standby pump
- Pressure controller on reactor - Pressure controller on line
Covered by (a), (b), (c)
(d) Regular inspection and maintenance of valves. (e) Put a blanking plate on drain flange plate. (f) Regular
(5) Valve fails closed or blocks
As for (1) and (3) - Overpressure in line before valve leading to rupture.
- Bypass valve in place
(6) Leak or drain left open
As for (1) to (5) - DEA released from pipework – hazardous. - Potential damage to surrounding
- FRC on line - Trip on pump
[Type text] equipment.
MORE OF
MORE FLOW
(7) Empty tank/leak in tank/LSL fails
As for (1) to (6)
- Level alarm on tank.
(8) Heat exchanger blockage
As for (1) to (7)
-
(9) Pump overpower or both pumps operating
- Heat exchanger cannot heat stream enough – DEA solidifies - Reactor overflow/overpressure - Excess DEA in reactor passing through process - Possible line rupture Same as (9)
- Electrically traced line for preventing solidification - FRC on line
Same as (9)
- Valves fail closed - Pressure controller on reactor -
(10) FRC gives incorrect value (too low) (11) Valve failure
LESS OF
LESS FLOW
(12) Lower pressure in reactor
Same as (9)
(13) FRC gives incorrect value (too high)
- Less reaction - Higher DEA outlet temperature from heat exchanger - Insufficient reactor pressure - Potential higher flow in other
-
inspection of lines to look for leaks. (g) Use flow controllers on all lines with the potential to leak. (h) Ensure regular inspection of tank for leakage. (g) Ensure good heat exchanger cleaning and inspect after cleaning. (h) Use a locking off procedure for pump not in use. (g) Surge meter to prevent pump overpressure (i) Check FRC regularly (j) Design valve for maximum pressure Covered by (a) to (j)
Covered by (a) to (j)
[Type text]
(14) Partial blockage/leak in pipe (15) Pump underpowered
(16) High reactor pressure
(17) Valve stuck partially closed (18) Fouling in pipes and heat exchanger
REVERSE
MORE OF
REVERSE FLOW
MORE PRESSURE
(19) Insufficient DEA in tank (20) High reactor pressure (21) Reactor isolation valve fails open
(22) Pump overpower (23) PIC gives wrong value (too low) (24) Thermal expansion of DEA due to heat
sections of line possibly leading to pipe rupture Same as (1), (6) and (13) Same as (13) - Backflow of nitrogen into DEA line Same as (13) - Reactor vessel rupture
Same as (13) Same as (13) - Reduces heat transfer which could lead to DEA solidifying Same as (13) - Potential cavitation in pump As previously discussed - Backflow of reactor contents (including hydrogen) to DEA line
Discussed previously -
- Relief valve for reactor - Pressure controller on reactor - Valves should fail closed -
- Level alarm on tank Reactor pressure control -
Covered by (a) to (j) (k) Fit non return valve to reactor inlet. Covered by (a) to (k)
Covered by (a) to (k) Covered by (a) to (k)
Covered by (a) to (k) Covered by (a) to (k)
Discussed previously Discussed previously
-
(l) Add FIC to all reactor inlet lines, shut down if backflow into DEA line is detected. Covered by (a) to (l) Covered by (a) to (l)
Discussed previously
Discussed previously
(m) Design pipes for higher pressure and
[Type text]
LESS OF
NONE OF MORE OF
LESS PRESSURE
NO PRESSURE MORE TEMPERATU RE
(25) Steam rate fluctuation to heat exchanger
Discussed previously
- Temperature controller on steam flow
(26) Blockage/ closed valves (27) Pump failure
Discussed previously
(28) PIC gives wrong value (too high) (29) Leakage
Discussed previously
(30) Valves more closed than expected (31) Solid DEA in tank with pump running (32) Excess steam in to heat exchanger
expansion Covered by (a) to (m) (n) Consider cascading flow and temperature control for heat exchanger steam Covered by (a) to (n) Covered by (a) to (n) Covered by (a) to (n) Covered by (a) to (n) Covered by (a) to (n) Covered by (a) to (n) Covered by (a) to (n)
Covered by (a) to (n) Covered by (a) to (n) (o) Add temperature control to tank
[Type text] LESS OF
LESS TEMPERATU RE
(36) Insufficient steam in to heat exchanger (37) Tracing failure
