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              Odor Removal Activated Carbon Design Method

1. Odor causing gases

    There are many odor causing gases in our environment. Here are some examples.  
   Nuisance Gas Properties    
Gas Classification Acid Gas   Alkaline Gas  
Gas Formula NH3 (CH3)3N H2S CH3SH
Gas Names ammonia trimethylamine hydrogen sulfide methylcaptan
Molecular Weight 17.03 59.11 32.08 48.11
Boiling Point  -33.4 3.5 -61.8 7.6
Barely Noticeable Lev1 (ppb) 100 0.1 0.5 0.1
Identifiable           Lev2 (ppb) 600 1 6 0.7
Smells                 Lev3 (ppb) 1000 5 20 2
Strong Odor         Lev 4(ppb) 2000 20 60 4

 
 

Nuisance Gas Properties

   
Gas Classification Neutral Gases      
Gas Formula  (CH3)2S  (CH3)2S2 CH3CHO C6H5CH:CH
Gas Names  methylsulfide dimethylsulfide aetaldehyde styrene
Molecular Weight 62.13 94.19 44.05 104.14
Boiling Point  38C 117C 20.2C 145C
Barely Noticeable Lv1 (ppb) 0.1 0.3 2 30
Identifiable            Lv2 (ppb) 2 3 10 200
Smells                   Lv3 (ppb) 10 9 50 400
Strong Odor         Lv4(ppb) 40 30 100 800

2. Specially treated pellet Carbon for various gas removal applications 
    Pellet Carbon For Nuisance Gas: General Specifications  
Target Gases Acid Gas Alkaline Gas   Neutral Gases    
Pellet Designator 4G-H 4T-B 4GG 4SA 4T-C 4T-F
Size 4mm Dia x 6mm L  4/6  4/6  4/6  4/6  4/6  4/6
Specific Gravity (g/ml)  0.40-0.45  0.50-0.60  0.43-0.48  0.48-0.55  0.48-0.56  0.43-0.48
Hardness (%)     >95     >95     >95     >95     >95     >95
Drying Weight Loss (%)     <5     <30     <5     <5     <20     <10
Benzene Adsorption (%)     >38      ---      >33     >25     >30     >20
Primary Effective Gases H2S,CH3SH NH3,(CH3)3N C6H5CH:CH (CH3)2S,(CH3)2S2 (CH3)2S,(CH3)2S2 CH3CHO,CH2O
Secondary Effective Gases C6H5CH:CH   H2S,CH3SH C6H5CH:CH C6H5CH:CH  
      (CH3)2S2 CH3SH    

 

Pressure Drop Consideration

Equilibrium Adsorption Consideration

`

 

 

Design Steps for one gas

(1) Odor Element Generation - A (kg)

      A= (C*M*Q*L/(22,400*1,000)) * 273/(273+T)

C: Gas Concentration (ml/M3=ppm), M: molecular weight (g/mol), Q: flow rate (m3/hr) L: life (hr), T: Temperature (C), 22,400: 1 mol gas amount (ml/mol), 1000: conversion from kg to g (g/kg)

(2)Activated carbon amount needed - B (kg)

     B= W1+W2

W1: Activated carbon needed from the equilibrium chart. 

    W1= (A*100)/X    X(%): The equilibrium adsorption % on each odor.

W2: Activated carbon needed from contact time calculations

    W2=LV*CT*SQ/SG

LV: Linear Velocity (m/sec)  CT: Contact Time (sec) 0.3-0.8 sec. SQ: Flow cross section area (m2)  SG: Specific gravity of activated carbon used 

Note: Please use an appropriate safety factor after computations: i.e. 1.3

The equilibrium gas adsorption amount can be expressed in the following formula within a certain range of gas concentration.       Xi=A*Ci**B   where

Xi=Gas adsorption amount (g) for 100g of  activated carbon carbon Ci=Gas concentration (ppm)  A & B are an experimental constant (see below)

Gas Classification Acid Gas   Alkaline Gas  
Gas  NH3 (CH3)3N H2S CH3SH
Gas Names anmonia trimethylamine hydrogen sulfide methylcaptan
Formula  Xi(g)=8.3xCi**0.063  Xi(g)=11.0xCi**0.079  Xi(g)=34.0xCi**0.126 Xi(g)=8.0xCi**0.129 :4T-C
Formula       Xi(g)=2.8xCi**0.355 :4G-H
       
Gas Classification   Neutral Gases    
Gas   (CH3)2S  (CH3)2S2 CH3CHO C6H5CH:CH
Gas Names  methylsulfide dimethylsulfide aetaldehyde styrene
Formula  Xi(g)=3.4xCi**0.091 :4T-C  Xi(g)=8.8xCi**0.145  Xi(g)=6.0xCi**0.086 Xi(g)=21.4xCi**0.150
Formula  Xi(g)=1.1xCi**0.310 :4SA      

 

If a granular carbon bed is preferred  in stead of pellet carbon, please see:

 TF treated granular carbon design (pdf) format

If a sheet carbon is  preferred in stead of pellet carbon, please see :

 7400W5 for acetaldehyde removal

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