PTQ Q2 2022 Issue

spacings were divided into four tray spacings. Figure 4 shows a section sketch of the overlay of new trays #112-116 (in blue) against the exist- ing trays #101-104 (in grey). New tray #116 was on the support ring of existing tray #104, while new tray #112 was on the support ring of existing tray #101. The existing sup- port rings, which were originally designed for two-pass trays, had to be completed for a full ring. The new trays #113-115 were supported by full expansion rings. Figure 5 shows the new expansion rings (in blue) and new support struts (in light blue) on existing column attachments. These support struts were to be welded on-site to an existing support ring and down- comer bolting bar for mechanical strength. In both Sections A and B, the existing 48 two-pass trays were successfully replaced with 60 HiFi trays without welding to the col- umn shell. The mist eliminator above Section A was inadequate to handle the increase in gas loads and had to be replaced. The existing mesh pad was supported in a sleeve with a diameter smaller than the column inner diameter (see Figure 6a ). The existing sleeve was cut and modi- fied into a support attachment for the new full-ID mist eliminator with L-hook fixation (see Figures 6b and 6c ). Section C: Sulzer VGPlus trays Section C originally had 47 two-pass round valve trays. This section for H 2 S removal has significantly less liquid load than Sections A and B, receiving only about 40-60% of the loaded methanol from Section B. The modification plan was to have

# 116

# 104

# 115

# 103

# 114

# 102

# 113

# 101

# 112

Figure 4 Overlap of new trays (in blue) on existing tray attachments (in grey)

new fixed valve trays with down - comers optimised for the design loads and operating range. Sulzer supplied two-pass VGPlus trays for this section. Section D is the pre-wash section with nine one-pass round valve trays. The existing trays were ade- quate for the new loads, and no modification was required for the revamp. Table 1 shows a summary of the new trays for the revamp. Installation One of the revamp targets was to complete the turnaround within 21 days, a week less than the ‘stand- ard’ 30 days. To meet this tight

Figure 5 3D image of expansion rings and support struts on existing column attachments

Figure 6a Existing gas sleeve for mesh pad; b Modified support ring for new mesh pad; c New mesh pad with L-hook

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