• Water Treatment
• Fine Chemicals / Pharma
• Fabrication Manufacturing
• CRYOCLEAN®
• Food Freezing and Chilling
• Double Glazing
• Glass Processing
• Heat Treatment
• Sulphur Recovery Burner Technology (SUREburner)

Oxygen Enrichment in Claus Plants – BOC SURE™ Technology

Many Claus plants today are working with:

•  increased sour crude feedstock
•  increasingly stringent environmental regulations
•  increased levels of acid gas or sour water stripper (SWS) gas
•  occasional lean acid gas feed

SURE™ oxygen enrichment technology from BOC

SURE™ oxygen enrichment technology can provide a cost-effective solution for increasing your plant's sulphur handling capacity.  It can also solve the problems associated with contaminants such as ammonia and hydrocarbons.

BOC has worked closely with WorleyParsons, the leading engineering contractor for Sulphur Recovery Units (SRU).  Since we first developed the BOC/Parsons burner in 1980s, the technology has been successfully applied in more than 60 facilities around the world.

Simple enrichment

Low level - or simple - enrichment is accomplished by injecting oxygen via a diffuser into the air-main to the SRU.

Generally, the sulphur plant will require no equipment modification other than the provision of a tie-in point for oxygen injection into the combustion airline.

A maximum oxygen enrichment level of 28% provides a capacity increase of approximately 30%.

Maximum enrichment – BOC SURE™ burner

At an enrichment level above 28%, the combustion-air piping in the conventional sulphur plant and the air-only burner are unsuitable for use with oxygen-rich air.  It is necessary to introduce oxygen into the reaction furnace separately from the air supply.

BOC supplies the proprietary SURE™ burner which has been specifically designed for this purpose.

The SURE™ burner is a self-cooled tip-mix burner with separate ports for acid gas, oxygen and air supply.

The burner can be used in both end-fired and tangential-fired furnace designs.  The intensive mixing characteristics of the SURE™ burner have been developed through extensive test work at the BOC pilot plant - a commercial scale sulphur recovery unit - and Computational Fluid Dynamics (CFD) modelling to give excellent contaminant destruction.

SURE™ Double Combustion

For operation with high levels of oxygen (> 45% oxygen enrichment), methods must be employed to mitigate high flame temperature in the reaction furnace.

The SURE™ Double Combustion process is the best available technology. providing full capability at up to 100% oxygen in an uncomplicated process that is easy to install, operate, and maintain.

Double Combustion, as the name implies, splits the heat release into two separate reaction furnaces with cooling between.

In the first reaction furnace, all amine gas, sour water stripper gas and all the air (if required) are fed to the SURE™ burner together with the supplied oxygen, the level of which depends on plant throughput. The tip-mix burner allows for thorough mixing, giving excellent contaminant destruction efficiencies. Only oxygen is split between the first and second reactors.

There is no sulphur condenser between the first waste heat boiler (WHB), and the second reaction furnace.  Also, there is no burner in the second reaction furnace.   By design, the gases exiting the first waste heat boiler and entering the second reaction furnace are substantially above the auto-ignition temperature of hydrogen sulphide and sulphur vapour, under all normal and turn-down operation conditions.  This system allows for low-pressure drop, which is easy to control and easy to install.

The result of this type of control is a temperature profile ideally suited to the Claus process.

Operating temperatures in the first reaction furnace are high enough to destroy ammonia and hydrocarbons, but remain well below refractory limitations.

The Double Combustion process illustrated here has been operating since 1990 at KOA Oil, Japan.

In the first reaction furnace, all amine gas, sour water stripper gas and all the air (if required) are fed to the SURE™ burner together with the supplied oxygen, the level of which depends on plant throughput. The tip-mix burner allows for thorough mixing, giving excellent contaminant destruction efficiencies. Only oxygen is split between the first and second reactors.

There is no sulphur condenser between the first waste heat boiler (WHB), and the second reaction furnace.  Also, there is no burner in the second reaction furnace.   By design, the gases exiting the first waste heat boiler and entering the second reaction furnace are substantially above the auto-ignition temperature of hydrogen sulphide and sulphur vapour, under all normal and turn-down operation conditions.  This system allows for low-pressure drop, which is easy to control and easy to install.

The result of this type of control is a temperature profile ideally suited to the Claus process.

Operating temperatures in the first reaction furnace are high enough to destroy ammonia and hydrocarbons, but remain well below refractory limitations.

A novel approach has used the benefits of a multi-pass Waste Heat Boiler (WHB) for plants with restricted plot space.  The zone between the first and second passes of the boiler is utilised as the second reaction furnace of the Double Combustion process.

In this situation, lances are installed in the channel head connecting the first and second pass of the WHB tube sheets (where the remaining oxygen can be added).  For the optimum design and location of the SURE™ burner and oxygen lances, BOC uses a validated CFD model.

This particular approach has been operational at API Falconara, Italy, since 1996 and at Shell, Puget Sounds, General Chemicals Anacortes and Exxon Chalmette with 100% oxygen since 2000.
The change-out of the WHB can improve energy efficiency at a plant through the generation of valuable high-pressure steam. 

Other energy efficiency benefits arise from the much-reduced process gas flow through the plant.  This reduces the converter reheat and incinerator fuel gas requirements to a minimum.  Reduced energy requirements significantly cut CO2 releases.

The benefits of using oxygen-enrichment in the Claus process

• increased sulphur recovery capacity
• reduced capital cost of both Claus unit and associated Tail Gas Treatment Unit (TGTU)
• reduced space requirement
• reduced maintenance requirement
• greater flexibility in handling feed gas composition variations
• increased availability of high-grade steam
• reduced project execution time
• ease of installation with minimum disruption to plant operation
  

The benefits of using SURE™ burner

• tip-mix burner maximises the effective and safe use of oxygen
• low pressure drop burner gives an additional 10-20% capacity
• longevity in high temperature corrosive environment
• contaminant destruction
• ammonia destruction
• carbon disulphide destruction
• hydrocarbon destruction
• BTX destruction in gas plant feed streams
• flexible design to allow operation on air, enriched air and pure oxygen
• high turndown
• burner design allows flame shaping to minimise hotspot formation on refractory
• internal burner-staging ensures more effective destruction of contaminants

Our capabilities

BOC has more reference plants for oxygen use in sulphur plants than any other company.

Around 40 SURE burners have been installed and seven Double Combustion units commissioned, of which four plants are now operating with 100% oxygen.

BOC has made a significant investment in SURE technology with the construction of the Claus burner development facility and the development of a validated CFD model.  From this, BOC has achieved 'best in class' for the provision of oxygen process technology in sulphur plants.

BOC engineers can evaluate your plant to assess the most suitable method of oxygen use and oxygen supply for your application, and advise you on the various oxygen supply options.

BOC can provide training for your staff in the operation of the unit and safety procedures for the use of oxygen.

For more information about BOC SURE™ technology email us