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simonm
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There is more chlorine in brash and green waste than clean wood.

 

Yes, simply because there is more ash in these parts of the foliage and bark than wood

 

 

The chlorine doesn't burn and corrodes the boilers

 

Well chlorine is an oxident so in that respect it doesn't burn but as its incidence in wood is less than .05% I doubt it is significant in corroding anything. Plastic coatings on the other hand do have lots of potential for forming acids, PVC will burn completely to form HCl which will combine with water and eat through stainless steel, incomplete burning gives dioxins.

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I doubt it is significant in corroding anything. [/b][/b]

 

 

It accelerates corrosion.

 

The design of new biomass-fired power plants with increased steam temperature raises concerns of high-temperature corrosion. The high potassium and chlorine contents in many biomasses are potentially harmful elements with regard to corrosion. This paper condenses the current knowledge of chlorine-induced, high-temperature corrosion and describes the potential corrosion problems associated with burning biomass fuels either alone or in blends with coal, for electricity production.

Chlorine may cause accelerated corrosion resulting in increased oxidation, metal wastage, internal attack, void formations, and loose non-adherent scales. The partial pressure of HCl in a biomass-derived flue gas, is not high enough to cause severe gas- phase corrosion attacks, but may provide scale failure and increased sulfidation of water walls in areas where locally reducing conditions occur due to poor combustion and flame impingement. The most severe corrosion problems in biomass-fired systems are expected to occur due to Cl-rich deposits formed on superheater tubes.

The presence of alkali chloride salts in deposits may cause accelerated corrosion well below the melting point of the salt. The corrosion can be severe in air but may be further enhanced by SO2 which may cause intra-deposit sulfation of the alkali chlorides liberating HCl or Cl2 gas close to the metal surface. In case the metal surface temperature becomes high enough for molten phases to form in the deposit, the corrosion may be even further enhanced

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I doubt it is significant in corroding anything. [/b][/b]

 

 

 

 

 

It accelerates corrosion.

 

 

 

The design of new biomass-fired power plants with increased steam temperature raises concerns of high-temperature corrosion. The high potassium and chlorine contents in many biomasses are potentially harmful elements with regard to corrosion. This paper condenses the current knowledge of chlorine-induced, high-temperature corrosion and describes the potential corrosion problems associated with burning biomass fuels either alone or in blends with coal, for electricity production.

 

Chlorine may cause accelerated corrosion resulting in increased oxidation, metal wastage, internal attack, void formations, and loose non-adherent scales. The partial pressure of HCl in a biomass-derived flue gas, is not high enough to cause severe gas- phase corrosion attacks, but may provide scale failure and increased sulfidation of water walls in areas where locally reducing conditions occur due to poor combustion and flame impingement. The most severe corrosion problems in biomass-fired systems are expected to occur due to Cl-rich deposits formed on superheater tubes.

 

The presence of alkali chloride salts in deposits may cause accelerated corrosion well below the melting point of the salt. The corrosion can be severe in air but may be further enhanced by SO2 which may cause intra-deposit sulfation of the alkali chlorides liberating HCl or Cl2 gas close to the metal surface. In case the metal surface temperature becomes high enough for molten phases to form in the deposit, the corrosion may be even further enhanced

 

 

Aye, that's what I was thinking!

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I doubt it is significant in corroding anything. [/b][/b]

 

 

It accelerates corrosion.

 

The design of new biomass-fired power plants with increased steam temperature raises concerns of high-temperature corrosion. The high potassium and chlorine contents in many biomasses are potentially harmful elements with regard to corrosion. This paper condenses the current knowledge of chlorine-induced, high-temperature corrosion and describes the potential corrosion problems associated with burning biomass fuels either alone or in blends with coal, for electricity production.

Chlorine may cause accelerated corrosion resulting in increased oxidation, metal wastage, internal attack, void formations, and loose non-adherent scales. The partial pressure of HCl in a biomass-derived flue gas, is not high enough to cause severe gas- phase corrosion attacks, but may provide scale failure and increased sulfidation of water walls in areas where locally reducing conditions occur due to poor combustion and flame impingement. The most severe corrosion problems in biomass-fired systems are expected to occur due to Cl-rich deposits formed on superheater tubes.

The presence of alkali chloride salts in deposits may cause accelerated corrosion well below the melting point of the salt. The corrosion can be severe in air but may be further enhanced by SO2 which may cause intra-deposit sulfation of the alkali chlorides liberating HCl or Cl2 gas close to the metal surface. In case the metal surface temperature becomes high enough for molten phases to form in the deposit, the corrosion may be even further enhanced

 

You didn't read my earlier post " high potassium and chlorine content in many biomasses" refers to things like miscanthus. Wood chip is a subset of biomass.

 

Also they are talking about raising (and superheating) steam and it is at these high temperatures that the fly ash will firstly melt and then condense on the superheater tubes. Our domestic boilers have water at less than boiling in them.

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You didn't read my earlier post " high potassium and chlorine content in many biomasses" refers to things like miscanthus. Wood chip is a subset of biomass.

 

Also they are talking about raising (and superheating) steam and it is at these high temperatures that the fly ash will firstly melt and then condense on the superheater tubes. Our domestic boilers have water at less than boiling in them.

 

Ok, I was just trying to explain the significance of chlorine content in biomass in relation to fuel for power stations, where the arb waste goes. :001_smile:

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