# US 7,608,230 B2 · Sample conditioning system for removing selenium from a gas stream

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- Number: US 7,608,230 B2
- Document ID: US7608230B2
- Status: Granted
- Kind: B2
- Application number: 11/471,108
- Filed: 2006-06-19
- Published: 2007-12-20
- Granted: 2009-10-27
- Earliest claimed: 2006-06-19
- Assignees: Apogee Scientific, Inc.
- Inventors: Scott E. McLaren; Kevin M. Fisher
- Web page: https://patentgrep.com/patent/US7608230B2

## CPC

- G01N 33/0013: {by a chemical reaction (a chemical reaction taking place or a gas being eliminated in one or more analysing channels G01N33/0024)}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

A sample conditioning system removes selenium from a flue gas sample to provide more accurate measure of mercury in the gas stream. Ammonia or another basic reagent is added to the sampled gas stream to increase the pH of the condensate, and thereby ensuring the removal of hydrogen selenide.

## Claims

### Claim 1

A method for conditioning a flue gas stream to remove selenium prior to measuring mercury in the gas stream, said method comprising:
adding a basic reagent to the gas stream to increase solubility of hydrogen selenide in water; and
removing moisture and soluble gases, including hydrogen selenide, from the gas stream.

### Claim 2 (depends on 1)

The method of claim 1 wherein the basic reagent comprises ammonia.

### Claim 3 (depends on 1)

The method of claim 1 further comprising adding a reducing agent to the gas stream to consume available oxidizing agents in the gas stream.

### Claim 4 (depends on 3)

The method of claim 3 wherein the reducing agent comprises propane.

### Claim 5 (depends on 1)

The method of claim 1 wherein moisture and soluble gases are removed from the gas stream by a condenser.

### Claim 6

A method for measuring mercury in a flue gas stream comprising:
adding a reducing agent to the gas stream to consume available oxidizing agents in the gas stream and convert oxidized forms of mercury in the gas stream to elemental mercury;
adding a basic reagent to the gas stream to increase solubility of hydrogen selenide in water;
removing moisture and soluble gases, including hydrogen selenide, from the gas stream; and
measuring elemental mercury in the gas stream.

### Claim 7 (depends on 6)

The method of claim 6 wherein the basic reagent comprises ammonia.

### Claim 8 (depends on 6)

The method of claim 6 wherein the reducing agent comprises propane.

### Claim 9 (depends on 6)

The method of claim 6 wherein moisture and soluble gases are removed from the gas stream by a condenser.