PTQ Q4 2025 Issue

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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