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Reducing NH3 slip from a NH3 water wash in a Chilled Ammonia Carbon Capture Process

IP.com Disclosure Number: IPCOM000250226D
Publication Date: 2017-Jun-13
Document File: 4 page(s) / 179K

Publishing Venue

The IP.com Prior Art Database

Abstract

Limiting the NH3 slip from the NH3 Water Wash in order to reduce the Sulphuric acid consumption in the DCH (Direct Contact Heater). A pumparound is used for the bottom section and a lean liquid stream from the stripper is sent to the top of the NH3 Water Wa?h column to wash the flue gas and reduce the NH3 slip to an acceptable level. A profile of the NH3 concentration in the vapor phase has been obtained with the current Aspen Plus model and is shown below the sketch . In the current example; the bottom section is 1.5 m high and the top section 3.0 ·m high. From 0 to 1.5 m, the NH3 concentration in the vapor phase decreases down to around 7500 ppmv.. In the top section, the NH3 concentration decreases quickly down to 0 ppmv and increase near the top of the column. It is believed that the NH3 slip is due to a flash of the lean liquid entering the NH3 Water Wash column at the top. In the current example the NH3 slip is 440 ppmv.

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312CWF783 ‐ Publication 

Background 

Reducing NH3 slip from a NH3 water wash in a Chilled Ammonia Carbon Capture Process.  

Technical Problem 

Limiting the NH3 slip from the NH3 Water Wash in order to reduce the Sulphuric acid consumption in  the DCH (Direct Contact Heater). 

Existing Solutions 

Currently the NH3 water wash comprises 2 sections: the bottom section removes the bulk of NH3  contained in the flue gas stream coming from the absorber. The top section is reducing the NH3 slip  until an acceptable level for the DCH (Direct Contact Heater), meaning an acceptable consumption of  sulphuric acid to control the NH3 emission.  

While the bottom section is using a liquid stream rich in NH3 and C02 , the top section uses a purified  stream from a stripper with a low concentration of NH3 and C02 in order to reduce the NH3 slip from  the NH3 water wash. The goal is to reach a NH3 slip around 200 ppmv to balance the heat duty  consumption of the stripper and the sulfuric acid consumption in the DCH section. 

The current solution leads to a non‐negligible consumption of sulfuric acid in the DCH and a substantial  heat duty in the stripper section which a key  figure when it comes to the total energy consumption of  the CAPs  system. 

 

Detailed Description 

A current configuration is shown in Appendix 1. A pumparound is used for the bottom section and a lean  liquid stream from the stripper is sent to the top of the NH3 Water Wa?h column to wash the flue gas  and reduce the NH3 slip to an acceptable level. A profile of the NH3 concentration in the vapor phase  has been obtained with the  current Aspen Plus model and is shown below the sketch . In the current  example; the bottom section is 1.5 m high and the top section 3.0 ∙m high. From 0 to 1.5 m, the NH3  concentration in the vapor phase decreases down to around 7500 ppmv.. In the top section, the NH3  concentration decreases quickly down to 0 ppmv and increase near the top of the column. It is believed  that the NH3 slip is due to a flash of the lean liquid entering the NH3 Water Wash column at the top. In  the current example the NH3 slip is 440 ppmv. 

Use a Pumparound for the top section in order to .  

Thus, the idea is to use a pumparound for the top section, in order to reduce lean solvent flash and  consequently reduce the NH3 slip from the NH3 Water Wash column‐‐overcome the flash of the lean  solution.  

An example is presented in Appendix 2.  According to this idea, the NH3 slip from the NH3 Water Wash  should be lower than in the current configuration, reducing the consumption of ...