SO2 Scrubbing Applications

Cansolv CO2 capture applications


SO2 Scrubbing Applications

The CANSOLV SO2 Scrubbing System and the TGT+ system can be used in many areas of the refinery or gas plant:

  • Fluid Cokers
  • Fluid Catalytic Crackers
  • Resid Fuel Fired Boilers
  • Sulphur Recovery Units
  • Process Heaters, Furnaces and Boilers
  • Satellite Sulphuric Acid Plants
  • Gasification Units

Fluid Catalytic Cracking Unit / Fluidized Coker Unit

The regenerable CANSOLV SO2 Scrubbing System is an ideal solution for refineries that are facing stricter sulphur emissions limits to air and water and that do not hydrotreat the FCCU/FCU feed or wish to take advantage of higher sulphur feedstocks.

It generates minimal effluent and allows the SO2 to be recovered as sellable sulphur or sulphuric acid. This can be achieved with minimal investment in the existing sulphur recovery unit (SRU) or in a single absorption sulphuric acid plant (SAP). The captured SO2 is pure and concentrated and can also be used to de-bottleneck the existing SRU capacity.

Sulphur Recovery Units

Modern upstream and downstream SRUs now require sulphur recovery efficiencies at levels higher than 99.9% and World Bank standard SOx emissions of less than 150mg/Nm3.

The highly efficient CANSOLV TGT+ system is an SRU tail gas treating unit (TGTU) that complements a new or existing SRU in upstream and downstream applications. Rather than reducing residual SO2 back to H2S, the residual tail gas is oxidized in an incinerator along with any other sour streams.

SO2 captured from the incinerator flue gas by the CANSOLV system, is recycled to the front end of the SRU, which reduces the amount of air required in the SRU to combust H2S into SO2.

The consequential reduction in overall inert gas load enables more sulphur throughput or a smaller SRU and also eliminates the need for oxygen enrichment.

Process Heaters, Furnaces & Boilers

Refiners may wish to burn heavy fuel oil (HFO) and petroleum coke (petcoke) to generate their net energy demand and to provide another outlet for the ‘bottom of the barrel’.

The CANSOLV SO2 Scrubbing System will be most interesting to refiners who have insufficient residue oil upgrading capacity, that are faced with rising gas prices and are impacted by the Marpol Annex VI regulations governing the sulphur content in bunker fuel oil.

HFO can either be burnt in purpose built co-generation power units or in existing refinery units by modifying burners and implementing fuel oil heating systems.

Burning HFO and petcoke, however, will often produce high SOx emissions and conventional scrubbers rely on expensive caustic reagents and generate large amounts of dissolved solids and waste water effluent.

The CANSOLV SO2 Scrubbing System can achieve strict emission compliance while delivering a pure SO2 stream for conversion into sellable sulphur or sulphuric acid. It offers refiners another outlet for cracked residue streams and petcoke to harness power by using them as internal refinery fuel.

Sulphuric Acid Plants

Sulphuric Acid Plant (SAP) tail gas desulphurization has long been dominated by alkali reagent type processes, which convert the SO2 to calcium or sodium sulphate, creating aqueous and solid wastes that contribute to landfill tonnage and expense.

The disposal expense of these by-products is eliminated by installing a CANSOLV SO2 Scrubbing System. The by-product of a Cansolv plant is a pure water-saturated gaseous SO2 stream.

This SO2 is recycled to the existing drying tower at the front end of the acid plant for conversion to additional sulphuric acid, thereby enhancing capacity and maximizing resource recovery.

Power flue gas desulphurisation

Based on the current availability and feasibility of alternatives, fossil fuels are assured to remain a significant source for the world’s electricity production.

Further, the combination of tightening environmental regulations on sulphur emissions and the increasing scarcity of low sulphur fuel (fuel gas, oil or coal) means that the power generation industry faces significant challenges when it comes to flue gas desulphurization (FGD).

The regenerable Shell Cansolv technology can easily adapt to varying levels of sulphur content fuel.

Be it a low sulphur fuel oil or a high sulphur coal, Cansolv's SO2 scrubbing is ideal for treating flue gases to industry leading emissions levels (less than 15 ppmv), while not relying on conventional alkali reagents such as lime, limestone or caustic.

Further, the large operating range of a CANSOLV SO2 Scrubbing System allows for ultimate flexibility in power plant operations in the form of optional fuel switching regardless of sulphur content.

When combined with the CANSOLV CO2 Capture System, Shell Cansolv's technology provides a complete gas capture system for power plants.

Metallurgical plants

The highly efficient CANSOLV SO2 Scrubbing System can be a cost-efficient solution to meet regulation and/or production needs, while providing substantial returns on investment from the additional SO2 captured being transformed into sulphuric acid.

  • Reduction in emissions from the sulphuric acid plant
  • Capture and concentration of SO2 from the secondary gas streams to allow for sulphuric acid production from these streams
  • Debottlenecking of the existing gas treatment unit by concentrating the SO2 in the gas streams prior to their feed to the sulphuric acid plant
  • Treating SO2 concentration variations to deliver a constant SO2 stream into the sulphuric acid plant
  • Reduction in costs and gas treatment unit complexity by using single absorption acid plant technology instead of double absorption technology
  • Increase in revenues by recycling the SO2 captured back to the sulphuric acid plant
  • Assurance that the gas treatment unit can deal with variations in production and SO2 concentration
  • Securing of assets and operations in the event of stricter regulations on SO2 emissions in the future
  • Avoids the use of once-through scrubbing systems and associated landfill or waste water issues and costs

Fertilizer plants

Fertilizer sulphuric acid plants face various challenges that force them to implement new strategies for SO2 treatment:

  • Strengthening regulations pertaining to SO2 emissions
  • Upgrade of their gas treatment process
  • Increased capacity or variations of the production
  • Secure assets and operations
  • Minimizing their environmental footprint

Addressing these challenges, the CANSOLV SO2 Scrubbing System enables:

  • Reduction in emissions from the sulphuric acid plant by capturing the acid plant tail gas SO2 and recycling it to the feed of the plant
  • Capture and concentration of SO2 from the secondary gas streams to enable sulphuric acid production from these streams
  • Reduction in costs and gas treatment unit complexity by using single absorption acid plant technology instead of double absorption technology
  • Increase in revenues by recycling the SO2 captured back to the sulphuric acid plant
  • Securing of assets and the operations in the event of stricter regulations on SO2 emissions in the future
  • Operation of the gas treatment unit in concordance with the principles of sustainable development

Sulphuric acid plants

As new legislation requires lower SO2 emissions from sulphuric acid plants, plants with single absorption sulphuric acid are increasingly faced with the challenge of upgrading to a double absorption sulphuric acid plant. Or, at the very least, to put in place a technology that would reduce their emissions from the sulphuric acid plant’s tail gas to reach double absorption levels. However, implementing double absorption technology in an existing single absorption acid plant can potentially imply:

  • Long shutdown periods of the gas treatment unit for construction
  • Additional shutdowns for catalyst changes
  • Expensive catalyst changes
  • Expensive capital investment costs
  • A more complex gas treatment unit

The regenerable CANSOLV SO2 Scrubbing System can replace the conventional double absorption technology or alkali scrubbing technology when upgrading single absorption sulphuric acid plants. Treating the tail gas from the acid plant, the CANSOLV technology recycles the SOcaptured back to the input of the acid plant.

Direct benefits of using Cansolv’s SO2 capture technology with single absorption sulphuric acid plants are:

  • Ease of implementation as minimal downtime is required on initial construction
  • No catalyst change out associated downtime
  • Decreased SO2 emissions to industry leading levels (<10 ppmv)
  • Generation of additional revenues from recycling the by-product SO2 back to the sulphuric acid process
  • Minimize CAPEX and OPEX

Other benefits from implementing the CANSOLV SO2 Scrubbing System are:

  • De-coupling the emissions from the plant operations
  • Concentration of additional lean SO2 streams to enable sulphuric acid production
  • Minimizing the size and complexity of the entire tail gas treatment line-up
  • Minimization of the liquid and solid effluents related to tail gas cleaning

Cansolv CO2 capture applications

The CANSOLV CO2 Capture System offers an industry leading solution, offering potential improvements over conventional options such as:

  • Low overall energy consumption
  • High tolerance to SO2
  • Superior kinetics
  • Low corrosion solvent
  • Low oxidative degradation
  • EOR grade CO2 purity

Recognising that demand for energy will continue to increase and that some level of fossil fuel use will remain within global energy systems, Shell believes that technologies such as carbon capture and storage (CCS) must play a critical role. CCS is the only currently available technology that can significantly reduce CO2 emissions from industrial sectors of the economy and is indispensable to achieve net zero emissions in line with global aspirations.

Coal-fired power plants

Coal-fired power generation is recognized as being the largest contributor of anthropogenic CO2 emissions.

The regenerable CANSOLV CO2 Capture System offers an effective and economical method to remove up to 90% of the CO2 from exhaust gases, and deliver them as a pure product for downstream use in Enhanced Oil Recovery (EOR) or for sequestration (CCS).

Using a Shell Cansolv CO2 capture solution to decarbonise emissions can enable extension of an existing asset or implementation of a new one.

Combined cycle natural gas power plants

The world’s energy needs will underpin the use of hydrocarbons for decades to come, so the focus should remain on lowering their carbon emissions. Gas is an essential energy source in the transition to a lower-carbon energy system. When burnt for power, gas produces around half the CO2 and one-tenth of the air pollutants that coal does.

CCS could revolutionise the way the world produces electricity, removing up to 90% of carbon dioxide emissions from gas-fired power generation.

The CO2 captured by the Shell Cansolv system at a natural gas plant can be used for EOR and/or CCS.

Chemical plants

As technologies employed in post-combustion CO2 capture (such as amine based technologies) are familiar and common to the chemical industry, rolling out CO2 capture is relatively straightforward compared to the same for the power generation industry. In chemical applications requiring CO2 as a feedstock, it may be possible to meet the needs of the chemical process while also avoiding CO2 emissions to atmosphere.

Steel and cement

Governments around the world are moving towards regulations that can address CO2 emissions from a wide variety of industries. CCS seems to be the only viable route to eliminate the bulk of emissions from activities such as steel and cement making on a reasonable timescale.

The potential advantage of a higher content of CO2 per unit of exhaust gas in steel and cement plants is that the overall economics may favour these applications since many of the proposed legislations consider amount of CO2 avoided as the economic mechanism in either a carbon tax or a cap and trade scheme.

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About Shell Cansolv

Shell Cansolv is an innovative, technology-centred company that offers its clients high efficiency capture solutions for the removal of sulphur dioxide (SO2) and carbon dioxide (CO2) from gas streams in various industrial applications.

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