MEETING ADNOCS CO & SO 2 EMISSION LIMITS - AT WHAT COST? CASE - - PowerPoint PPT Presentation

MEETING ADNOC’S CO & SO2 EMISSION LIMITS - AT WHAT COST?

CASE STUDY

Middle East Sulphur Plant Operations Network 2017

October 16th, 2017

GASCO: Mr. Dheeraj Nagwani Senior Process Engineer

SUMMARY OF CONTENT

Introduction & Facilities Description Conclusion CO Emission SO2 Emission

> As per ADNOC COP, emission limits from SRU stack are restricted to:

• Sulphur dioxide (SO2) : 2000 mg/Nm3 (700 ppmv)
• carbon monoxide (CO) : 500 mg/Nm3 (400 ppmv)

> To check compliance, GASCO conducted a study for Habshan Complex SRUs to:

• Identify current CO and SO2 emission levels
• Evaluate possible options/solutions with cost estimate to meet the ADNOC CoP

emission requirements

INTRODUCTION

FACILITIES DESCRIPTION

Habshan-0 U-50/51 Habshan-1 U-52/53/54/57 Habshan-2 U-58/59 Habshan-5 U-550/551/552/553 OAG U-152/153 3 Stage Claus CBA Process CBA Process SUPERCLAUS Amine Based TGTU Capacity: 400TPD/Unit SRE: 97.5% Capacity: 600 TPD/Unit (U-57 : 640 TPD) SRE: 98.8% Capacity: 740TPD/Unit SRE: 99% Capacity: 800TPD/Unit SRE: 99% Capacity: 1300TPD/Unit SRE: 99.9%

TOTAL CAPACITY 11500 TPD Sulphur

CO EMISSIONS

Investigating current CO emission levels

>

An evaluation of the CO destruction in eight SRU incinerators and related stacks were conducted to investigate the current CO emission from Habshan SRUs

>

The comprehensive “Incinerator on Site Field Testing” for all the units were performed

>

The incinerators were tested at various temperatures

CO EMISSIONS

U-52/53/54/57

1552 880 517 1325 1060 2950 665 400 800 1200 1600 2000 2400 2800 3200 620 640 660 680 700 720

CO concentration at 3mol% O2 (ppmv DRY) Incinerator Temperature (°C)

U 52/53/54/57 Incinerator Temperature and CO Concentration at 3mol% O2 (dry) ˃

At ~700°C, the CO concentration is still more than 100 ppm higher than the ADNOC limit of 400 ppmv

˃

It is expected that ADNOC CO limit can be achieved at above 725°C incinerator

• perating temperature

ADNOC LIMIT: 400 ppmv

CO EMISSIONS

U-52/53/54/57

˃

At ~690°C, the CO concentration is exactly same as ADNOC limit of 400 ppmv

˃

At ~710°C, CO emission from U-58/59 will be well below the 400 ppmv limit

ADNOC LIMIT: 400 ppmv

1981 2221 652 286 2535 1245 1428 2027 400 800 1200 1600 2000 2400 2800 600 620 640 660 680 700 720

CO concentration at 3mol% O2 (ppmv DRY) Incinerator Temperature (°C)

U 58/59Incinerator Temperature and CO Concentration at 3mol% O2 (dry)

CO EMISSIONS

U-152/153

˃

At ~685°C, the CO concentration is exactly same as ADNOC limit of 400 ppmv

˃

At ~700°C, CO emission from U-152/153 will be well below the 400 ppmv limit

1682 2099 273 2558 2481 587 266 469 400 800 1200 1600 2000 2400 2800 630 640 650 660 670 680 690 700 710

CO concentration at 3mol% O2 (ppmv DRY) Incinerator Temperature (°C)

U 152/153 Incinerator Temperature and CO Concentration at 3mol% O2 (dry)

ADNOC LIMIT: 400 ppmv

CO EMISSIONS

Summary

>

At 650°C, the current CO levels are in the range of 1100 to 2300 ppmv range

>

All existing incinerators are capable of reducing the CO emissions to less than 400 ppmv

>

In order to achieve the required CO emission, the incinerators must be

• perated at higher temperatures as compared to current value of 650°C

>

Required estimated incinerators Operating Temperatures are:

• CBA SRUs U-52, 53, 54 and 57 :

750°C

• CBA SRUs U-58 and 59 :

710°C

• SuperClaus SRUs U-152 and 153 : 700°C

CO EMISSIONS

Evaluation of various options for CO emission reduction

• 1. Increasing Incinerator Operating Temperature

CO emission limit can be achieved at higher incinerators operating temperatures, however it will lead to increased fuel gas consumption and increased CO2 emission

>

At 100% volumetric capacity

• Additional fuel gas required : 4.8 MMSCFD
• Estimated additional fuel gas cost: US$ 4.25 million per year (*)
• Additional CO2 emission: 105493 tons per year

>

At current operating capacity

• Additional fuel gas required : 3.35 MMSCFD
• Estimated additional fuel gas cost: US$ 3 million per year (*)
• Additional CO2 emission: 74244 tons per year

(*) Fuel gas cost considered is 2.6 US$/MMBTU

CO EMISSIONS

• 2. Installing Hydrogenation Reactor/Catalyst

> An alternate solution is to install additional hydrogenation catalyst reactor/bed to convert

the CO in the tail gas to CO2

> For SO2 and elemental Sulphur (S8) the reactions are as follows:

SO2 + 3H2 = H2S+ 2H2O & S8 + 8H2 = 8H2S

> CO reacts with water vapor (H2O) present in the tail gas to release CO2 and H2:

CO + H2O = CO2+ H2

Hydrogenation Reactor Incinerator

Tail Gas SO2, S , H2S, CO

H2S,CO2, H2 SO2,CO2

CO EMISSIONS

ADVANTAGES

>

Lower temperature incinerator operation, significant reduction in fuel gas consumption because of: a) Exothermic reactions b) Increase in H2 c) Lower CO levels (<100 ppmv), further combustion not needed DISADVANTAGES

>

New equipment required, Very high CAPEX & additional plot space requirement

>

Reduced plant throughput due to pressure drop in additional equipment ECONOMIC EVALUATION

>

Estimated Equipment and Catalyst Cost: 14 MMUSD

>

Estimated total installed cost : US$ 45 million (*)

>

Estimated fuel gas cost saving: 11 MMUSD/year (*)

>

Reduction in CO2 emission: 44%

(*) Fuel gas cost considered is 2.6 US$/MMBTU. Considering all units are operating at maximum volumetric capacity. Saving numbers are reported as compared to high temperature

• peration option for CO reduction.

CO EMISSIONS

• 3. Lowering Reaction Furnace Temperature

>

It reduces the amount of CO formed in the reaction furnace

>

However, acid gas at Habshan is relatively lean and contains BTEX

>

Minimum reaction furnace temperature of 1050°C is required to ensure proper BTEX destruction to avoid catalyst deactivation

>

Lowering the furnace temperature would result in BTEX breakthrough and catalyst deactivation in Claus reactor

>

Therefore, CO reduction by this option is not feasible

CO EMISSIONS

• 4. Lowering CO2 Content in the Acid Gas

>

CO formation in the SRU reaction furnace depends on CO2 content in acid gas.

>

The current CO2 level in acid gas is approx. 45mol%

>

Lowering CO2 content in acid by 20 mol% would result in CO formation reduction by approx. 19%. However, this would not comply to ADNOC COP CO emission regulations

>

With a 20% reduction in CO2, the CO levels in stack will still be at least four time higher than ADNOC limit.

>

Major investment is needed as Acid Gas Enrichment technology would be needed to improve the acid gas quality.

>

Therefore this option is not considered feasible for further evaluation

CO EMISSIONS

• 5. Incinerator modification / replacement

>

Another possible option could be incinerator modification

>

CFD analysis is to be carried out to determine whether it is possible to improve mixing in incinerators via installation of checker walls or other internals

>

Installation of internals in existing incinerators could reduce the CO emissions

>

Capex impact for this option might be an additional 4-5 MM Euro each for adjustments/replacement of incinerator

SO2 EMISSIONS

Identifying design SO2 emission levels

>

Sulphur Recovery Units 52/53/54/57/58/59:

• As per design, all the units are expected to achieve 99% Sulphur

recovery

>

Sulphur Recovery Units 152/153:

• As per design, units U-152/153 are expected to achieve 99% Sulphur

recovery

>

A Sulphur Recovery efficiency of approximately 99.7% would be required to achieve 2,000 mg/Nm3 (700 ppmv) SO2 in the stack gas

>

Therefore, existing SRUs at Habshan are not currently designed to meet the ADNOC CoP emissions requirements as stated above

Evaluation of various options for SO2 emission reduction

SO2 EMISSIONS

Jacobs licensed Sulphur Recovery Units 152/153: B&V Licensed Sulphur Recovery Units 52/53/54/57/58/59:

>

Amine based Tail Gas Treatment (TGTU) on the back end of the CBA SRU’s would be required

>

Single TGTU for three SRU’s 52/53/54 and similar arrangement for the three SRU’s 57/58/59

>

Estimated cost of a single TGTU for 2000 MTPD of Sulphur is approx. USD 55 million

>

Estimated schedule : 4 months for FEED and 24 months for EPC.

>

Typically Plot: 65 m X 110 m plot area.

>

Additional tail gas treating units would be required

>

Either a new SCOT unit dealing with Super Claus

• ff-gases

>

Or a Consolv unit (or other scrubbing process) dealing with SO2 gases from the incinerator will be required

>

The SCOT unit dedicated to one SRU train would cost roughly 50 MM Euro (total for two 100 MM Euro)

Independent Consultant

>

Amine based TGTU would be required

>

Estimated CAPEX for all the Units would be ~400 MMUSD

>

There will be OPEX impact

• f ~110MW for all the

SRUs

SRU net energy balance at various SREs

Sulphur Recovery Efficiency 97% 99% 99.3% 99.7% 99.9% kWh per Metric ton "S" produced +1458 +1401 +1033 +913 +853

>

As SRE increases, the net energy produced from a SRU decreases

>

As the energy consumption increases (or the net energy produced decreases) so too increased fuel burning

>

This will emit additional CO2 emission, which is undesirable outcome in a time when carbon emission reduction is among the top environment

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SO2 EMISSIONS

CONCLUSION

>

Habshan SRU’s are not designed to meet SO2 emission levels as stipulated by ADNOC COP.

>

All existing SRU incinerators are capable of reducing the CO emissions to less than 400 ppmv at higher operating temperatures as compared to current value of 650°C.

>

While endeavoring for lower SO2 and CO emissions may be beneficial from environmental point of view, it does not come free of cost. In fact, it comes with substantial increase in cost.

>

Right balance between emissions regulations vs energy efficiency / CAPEX / OPEX for existing operating SRU’s is to be established by assigned regulatory bodies.

Thank You!