RAW PROPORTIONAL TOXIC SAMPLER FOR SAMPLING EXHAUST

• US 20130276552A1
• Filed: 04/20/2012
• Published: 10/24/2013
• Est. Priority Date: 04/20/2012
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Administrator Of The United States Environmental Protection Agency
• Original Assignee: The USA As Represented By The Administrator of The United States Environmental Protection Agency
• Inventors: SANCHEZ, Lawrence James, McDonald, Joseph, Schenk, Charles
• Granted Patent: US 8,887,554 B2
• Time in Patent Office: Days
• US Class Current: 73/863.03
• CPC Class Codes: G01N 1/2247 Sampling from a flowing stream of gas
• CPC Class Codes: G01N 1/2252 in a vehicle exhaust

Abstract

Components of interest are captured on a resin column from a sample of exhaust gas from an operating vehicle. Makeup air is added to the residual exhaust gas flow exiting the resin column at a junction downstream of the resin column. Makeup air flow rate is determined using a laminar flow element and pressure and temperature gauges associated therewith. The sample and the makeup air are drawn together through a blower and the flow rate through the blower is calculated based on differential pressure across the blower and temperature of the gas drawn through the blower. The controller adjusts a proportional control valve in the makeup air line to regulate the sample flow rate, taken as the blower flow rate minus the makeup air flow rate, at a predetermined proportion of the exhaust gas flow rate.

Claims

1. An apparatus for capturing components of interest from vehicle exhaust gas, comprising:

a device for determining exhaust gas flow rate;

a sample tube for capturing a sample of exhaust from an operating vehicle and introducing the captured sample into a sample line;

a resin column connected to the sample line for receiving the exhaust gas sample and selectively capturing the components of interest on the resin, with a residual exhaust gas flow exiting the resin column;

a makeup air line for adding makeup air to the residual exhaust gas flow at a junction downstream of the resin column;

a laminar flow element for receiving a flow of makeup air introduced into the makeup air line and measuring the flow rate of the makeup air;

a proportional control valve for controlling the makeup air flow rate;

a blower for drawing the sample through the sample line, the makeup air through the makeup air line and the combined sample and makeup air through a blower inlet line;

associated with the blower, pressure sensors in the blower inlet line and downstream of the blower and a temperature sensor; and

a controller for calculating the makeup air flow rate and blower flow rate through the blower, based on signals from the temperature and pressure sensors associated with the blower, and controlling the proportional control valve to indirectly regulate the sample flow rate, taken as the blower flow rate minus the makeup air flow rate, as a set percentage of the exhaust gas flow rate.

2. The apparatus of claim 1 further comprising an ice bath in which the resin column is contained.

3. A process for capturing components of interest from vehicle exhaust gas comprising:

capturing a sample of exhaust gas from an operating vehicle;

passing the captured sample through a resin column and selectively capturing the components of interest on the resin with a residual exhaust gas flow exiting the resin column;

adding makeup air to the residual exhaust gas flow at a junction downstream of the resin column;

measuring the flow rate of the makeup air utilizing a laminar flow element;

utilizing a blower, drawing the sample through the sample line, the makeup air through the makeup air line and a combination gas stream of the sample and makeup air through a blower inlet line;

detecting inlet temperature and pressure of the combination gas stream in the blower inlet line;

detecting outlet pressure of the combination gas stream exiting the blower;

calculating the makeup air flow rate based on signals from temperature and pressure sensors associated with the laminar flow element;

calculating the blower flow rate based on signals from the detected inlet temperature and pressure and the detected outlet pressure; and

controlling the proportional control valve to regulate the sample flow rate taken as the blower flow rate minus the makeup air flow rate.

4. The process of claim 3 further comprising determining the flow rate of the exhaust gas and wherein the proportional control valve is controlled to provide a sample flow rate which is a predetermined proportion of the determined flow rate of the exhaust gas.