ABOUT THE TECHNOLOGYFor ultra-high levels of sulphur recovery, the CANsOLv TGT+ sour gas treating system can serve as a destination for all the plant’s sour gas streams, including:n flash gases from the acid gas removal unit (AGRU);n treated residue gas from the acid gas enrichment unit

(AGEU);n tail gas from the Claus sulphur recovery unit (sRU);n sulphur degasser off-gas; n sour water stripper off-gas; andn disulphide oils generated in caustic treating of

extracted natural gas liquids (NGL) or condensate.

In addition, the CANsOLv TGT+ system is highly adaptive to changes in process loads and the type and quantity of the compounds being treated.

The system combines the following technologies:n the CANsOLv sO2 scrubbing process; andn the shell Global solutions sulfinol® or ADIP® process.

AT A GLANCECustomer driver: Growing development of highly sour natural gas resources; increasingly stringent emission regulations

Solution: The CANsOLv tail gas treating plus (TGT+) system for ultra-high sulphur recovery is based on Cansolv Technologies Inc.’s sulphur dioxide (sO2) scrubbing process*

Value delivered: Cost-effective and simplified process line-up with centralised treating of all sulphur-containing process off-gases

Proof point: since 2002, 19 CANsOLv licensed units have come online or are under construction

CANSOLV® TGT+ For ultra-high levels of sulphur recovery

Shell Global Solutions

Natural gas reservoirs brought into production in recent years have contained increasing quantities of carbonyl sulphide, mercaptans and other organic sulphur species as well as hydrogen sulphide and carbon dioxide. More complex process line-ups are required to manage these contaminants. Tightening product specifications and stricter environmental emission standards have added additional levels of complexity.

The CANsOLv TGT+ system is an integrated sour gas treating solution that enables ultra-high overall sulphur recovery efficiency (up to 99.99% of the total sulphur present in the feed gas to the processing plant) from sour gas streams while minimising process line-up complexity and cost.

Figure 1: The CANsOLv TGT+ system. Tail gas from the Claus sRU and overhead off-gases from the AGRU flash gas absorber, AGEU and degasser are routed directly to the thermal incinerator, where the sulphur species are burned to sO2. The incinerated gas is cleaned and cooled in a wash tower, and then enters the CANsOLv sO2 absorber where sO2 is preferentially removed.

FEEDGAS

SULPHUR

Regeneration gas(H2O, RSH)

Acid gas (H2S, CO2, RSH, COS)

Flash gas

Disulphide oils

Sales gas

NGL

Sweepgas

AGEU off-gas

Quench water (sulphates)

AGRU

AGEU

ClausSRU

MSU NGLextraction

Incineratorand quench

Degasser

CANSOLV

Caustic wash

Tail gasAcid gas

The CANsOLv sO2 scrubbing process is a post-combustion regenerable wet scrubbing process that uses a proprietary aqueous amine solvent to remove sO2. The captured sO2 is recycled as a pure stream to the sRU reaction furnace, where it reacts with incoming H2s in the acid gas to form elemental sulphur.

sRU tail gas and other sulphur-containing gas streams are directed to a thermal oxidiser where all the sulphur compounds are converted to sO2 (Figure 1). The incinerated gas is cleaned and cooled in a wash tower before entering the CANsOLv sO2 absorber, where sO2 is selectively removed.

The CANsOLv solvent is highly selective to sO2. No other compounds in the gas are absorbed: they are discharged directly to atmosphere through the stack. The sO2-containing solvent leaves the absorber and is regenerated using steam to produce a concentrated sO2 stream that can be accommodated by the sRU.

BUsINEss vALUEThe CANsOLv TGT+ line-up helps to achieve the most stringent emission standards mandated in different jurisdictions, including those mandated by the World Bank (sO2 stack emission <150 mg/Nm3), at competitive capital and operating costs while minimising process line-up complexity.

Compared with conventional process line-ups used to treat complex gases, CANsOLv TGT+ offers:n an increase in the overall sulphur recovery efficiency to 99.99%; n a decrease in complexity of the process line-up; n an outlet for the disulphide oils; and n competitive capital and operating costs.

For further information, please visit our website at www.shell.com/globalsolutions

shell Global solutions is a network of independent technology companies in the shell Group. In this material, the expressions “the shell Group”, “shell” and “shell Global solutions” are sometimes used for convenience where reference is made to these companies in general, or where no useful purpose is served by identifying a particular company.

The information contained in this material is intended to be general in nature and must not be relied on as specific advice in connection with any decisions you may make. shell Global solutions is not liable for any action you may take as a result of you relying on such material or for any loss or damage suffered by you as a result of you taking this action. Furthermore, these materials do not in any way constitute an offer to provide specific services. some services may not be available in certain countries or political subdivisions thereof.

Copyright © 2011 shell Global solutions International Bv. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical including by photocopy, recording or information storage and retrieval system, without permission in writing from shell Global solutions International Bv.

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pRooF poINTssRU TAIL GAs APPLICATIONA CANsOLv sO2 scrubbing process has operated in a 30-t/d sRU tail-gas application at a European chemical plant since 2002. It desulphurises the flue gas from a thermal oxidiser that receives feed streams, including Claus unit tail gas and a side stream of waste high-sulphur compounds, that accumulate in storage from operations. Recycling sO2 to the sRU expands its sulphur-recovery efficiency by reducing the thermal stage combustion air requirement while controlling total sulphur emissions to less than 100 ppmv and as low as 20 ppmv.

The operation of the plant has been stable and reliable. In addition, solvent degradation has been lower than expected, which indicates a very low make-up requirement.

sPENT ACID REGENERATION APPLICATIONThe CANsOLv sO2 scrubbing process has treated tail gas from a 400-t/d spent acid unit at the sulphuric acid plant at a refinery in California, UsA, since 2002. The recovered sO2 is sent to the front end of the acid plant for conversion to sulphuric acid.

Normal operation has demonstrated a steady-state sO2 concentration in the treated gas of between 10 and 20 ppmv. The process has been easy to adapt to changing conditions.

HAvE you CoNsIdEREd How you CAN

n achieve 99.99% overall sulphur recovery efficiency in your sour gas processing facility?

n cut the cost of sulphur recovery?

n reduce the complexity of your sour gas treating facility while achieving higher recovery?

HIGH-PERFORMANCE GAs-TREATING sOLUTIONs sERIEs

ARGUARGU

FEEDGAS

Tail gas treating

Sulphur degassing SULPHUR

TO STACK

C2 treating

LPG treating

NGLextraction

TREATED GASMSU

AGEU

SRU

*so2 and Co2 emission control specialist Cansolv Technologies Inc. is a wholly owned subsidiary of shell Global solutions International Bv.AdIp and sulfinol are shell trademarks.CANsoLv is a Cansolv Technologies Inc. trademark.