TGTU recycle
Amine loss makeup
Q-8
Vent to incinerator
TGTU to SRU
Amine makeup
Lean amine
1
Condenser
39
38
Amine cooler
31
Q-5
Amine absorber
Blowdown
RCYL-2
14
32
37
10
RA pump
28
29
30
Regenerator
13
VLVE-100
LR HEX
Rich amine
Steam
34
1
Q-4
Reboiler
36
Tubes
Q-Reb
33
LA pump
35
Condensate
27
Q-7
Q-2
Q-3
1
Cooling tower
26
25
Quench
RCYL-1
Cooler
Chiller
24
Gas heater
SRU tail gas to TGTU
Hydrogenation reactor
Q-6
5
Makeup
17
18
20
21
CW pumps
23
4
22
Q-9
Waste heat
Purge
Q-1
Figure 1 Typical tail gas treating unit
• Recover more than 99% H₂S from this stream (to recycle back to the SRU). • Maintain <100 ppm of H₂S in the absorber vent line routed for the incinerator (minimising eventual SOx emissions). • Slip >90% of the CO₂ (to ensure SRE is not affected). A process simulator suitable for accurately modelling sour gases and based on operating data from hundreds of sul- phur facilities units globally will be utilised (Bryan Research & Engineering, LLC, 2025). Process simulation models will be built for all these bespoke variables, and their respon- siveness to various cases will be tracked and reported. This article should give readers deep insight into how a TGTU responds to changes in key process conditions and offer a technical conclusion on the best design and operational boundaries of the unit. Analysis and discussion of results The fixed variables across all the scenarios, unless stated otherwise, will be a maximum flooding percentage of 70% in the towers (letting the diameter float), an L/G solvent to gas flow ratio of 3 (on a mass basis), an amine regenerator reboiler steam rate of 130 kg/m³ of amine, and a selective MDEA-based solvent at a temperature matching the feed. Absorber dimensions As shown in Figure 2 , as the height of the random packing in the absorber increases, H₂S removal efficiency improves because of more mass transfer surface area and contact time (as seen via the downward trend of the H₂S ppm in the absorber vent line). However, this comes at the cost
primary focus of the remaining discussion will be a thor- ough scrutiny of a TGTU amine absorber, using process simulation models of these towers under various conditions to analyse performance and identify opportunities to drive performance improvements. The variables selected for the evaluation of a TGTU amine absorber will be the following: Absorber dimensions. v Amine chemistry. For this study, a characteristic tail gas stream that has undergone hydrogenation and cooling consistent with some of the most common sulphur recovery facilities around the world will be used, as shown in Table 1 . The goal while comparing various operating scenarios will be to meet the following objectives: w Lean amine circulation rate. x Lean amine temperature.
Typical TGTU absorber feed conditions
Temperature
45°C
Pressure
0.15 kgf/cm2 (g)
Standard vapour flow Composition (mol %) H₂S
10,000 m3/h or ~11,500 kg/h
2 1
CO₂
H₂ N₂
0.5 90 6.5
H₂O
Table 1
88
PTQ Q4 2025
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