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Hydrogen Unit debottlenecking

– An Innovative Approach

S.K. Goel

BPCL Mumbai Refinery

International Conference on

Refining Challenges & Way Forward

Hydrogen Unit Process Details

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Need for Innovation

Unit Capacity 49,000 MTPA (148.5 MTPD)

Plant Commissioned In August 2005.

Hydrogen availability low because of reduced thruput, impacting HSD Production

Issues –

Low Pre-reformer temperature, close to hydration limits

This required lower firing in bottom section of reformer, which in turn caused higher skin temperature in upper sections of the reformer.

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Bottlenecks

Unit was revamped in 2008 to include CRU off gas as part of the feed. This helped to some extent to increase pre-reformer temperature

Problem aggravated with switch over reformer feed from naphtha to natural gas, since the reformer firing reduced. There was a sharp drop in Pre-reformer temperature.

There were 5 tube failures, causing expensive shut down’s. Unit was operated at reduced throughput & tube max skin temperature limited to 945 deg C.

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Possible solutions

Licenser suggested to augment heat transfer area in reformer convection section. This was not found feasible, due to space limitations in the unit & needed a major revamp.

Other Licensers suggested duct firing or a convective reformer. These were capital intensive & also needed higher energy consumption.

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BPCL Innovation

The innovation emerged from the following thought process.

Can we use steam superheat space for process pre-heat? or

Can we augment process pre-heat instead of steam superheating to such a high degree, which was really not needed.

A closer look at the process revealed that part of lower temperature steam from feed heat exchanger can be exported directly, which would augment process pre-heat.

The concept was agreed by Process Licenser, who supported for finalizing the process Design.

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NHGU Prereformer Temperature Profile

410430450470490510

0 20 40 60 80 100

% Catalyst Bed

Tem

pe

ratu

re

Naphtha feed case

Prereformer Temperature Profile

N H G U P r e r e fo r m e r T e m p e r a t u r e P r o f i le

4 1 0

4 3 0

4 5 0

4 7 0

4 9 0

5 1 0

0 2 0 4 0 6 0 8 0 1 0 0

% C a t a ly s t B e d

Te

mp

era

ture

N a p h th a fe e d c a s e R L N G + C R U o f fg a s fe e d c a s e

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Steam Network

320 °C

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Steam Network

320 °C

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Post Modification –

Pre-reformer Bed Temperatures

410

420

430

440

450

460

470

480

490

500

510

0 10 20 30 40 50 60 70 80 90 100

Naphtha Case

RLNG Case

After Modification

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Results Achieved

Pre-reformer minimum bed temperature increased by 15 deg C & tube skin temperature dropped by 10 deg C

Fuel reduction – 4 MT/D

CRU off gas – No longer essential in the feed, thus unit load can be increased independently during CRU shut down.

Unit rated capacity achieved with 962 deg C max skin temperature & natural gas feed.

The idea won BPCL Chairman’s award at Ideas 2011 Platform. This is the highest in-house award to nurture Innovation & Talent in the organization

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Thank you