N.M. Admin. Code § 20.2.14.301

Current through Register Vol. 35, No. 21, November 5, 2024

Section 20.2.14.301 - PROCEDURE I, METHOD

A. Principle: Particulate matter is withdrawn at an approximately isokinetic rate from the source, the large (over 2u) [over 2 micrometer] particles separated from the gas stream, and the fine particles collected on a filter. The weight of the fine particles is determined gravimetrically after removal of uncombined water.

B. Apparatus:

(1) Sampling Train: The recommended sampling train is shown schematically in Figure 1 (20.2.14.302 NMAC). It is based on the US EPA sampling train described in the Code of Federal Regulations, Title 40, Part 60, Appendix A, Method 5, Section 2.1 (hereinafter referred to as US EPA Method 5). To the Method 5 train is added a particle separator. The purpose of the particle separator is to trap essentially all of the particles greater than 2u [two micrometers]; to do this, a certain gas flowrate is required through this device as specified in Section 2.2.1.3.

(2) Nozzle: Stainless steel (type 304 or 316).

(3) Probe: Pyrex glass, insulated and heated uniformly to a temperature sufficient to prevent condensation from occurring at any point in the tube. For lengths greater than about 8 feet, a metal tube may be used. Incoloy 825 is preferred, but types 304 or 316 stainless steel are acceptable. Long probes shall be reinforced or supported to prevent excessive droop or gas stream whip. For sampling stacks carrying electrically charged particles (as for installations using electrostatic precipitators), the probe shall be grounded to prevent electrical shock to personnel and the inner shell of the probe shall be electrically conductive and shall be grounded to prevent size discriminative trapping of particles within the probe.

(4) Particulate Separator and Filter: The particle separator and filter system shall be housed in a temperature-controlled container.

(a) Particle Separator: The particle separator shall be a cascade impactor, such as the Andersen Mark II or Mark III Stack Head, manufactured by 2000 Inc., Atlanta, Georgia, or other if approved by the Department. The stack head must be modified to use only five of the collection plates arranged in the following order 0, 1, 2, 3, 4, 1 (manufacturer's numbers) and a filter holder as specified in subparagraph (b) of paragraph (4) of subsection B of 20.2.14.301 NMAC. The complete arrangement is shown in Figure 2 (20.2.14.303 NMAC). The gas flowrate through the stack head must be controlled to maintain a particle impaction efficiency of 50% on plate 4 for particles of 2 microns aerodynamic diameter. The procedure for doing this is described in paragraphs (3) and (4) of subsection D of 20.2.14.301 NMAC.

(b) Filter Holder: The filter holder shall immediately follow the last collection plate, as indicated in Figure 2 (20.2.14.303 NMAC), and contain a filter similar to those specified in paragraph (2) of subsection C of 20.2.14.301 NMAC.

(5) Metering System: Vacuum gage, leak-free pumps, thermometers capable of measuring to within 3 degrees Fahrenheit., dry test meter with 2 percent accuracy, and related equipment, as required to maintain an approximately isokinetic sampling rate through the probe and specified flowrate through the Andersen Stack Head, and to determine sample volume.

(6) Other Sampling Train Equipment: Pitot tube (type S, or equivalent), impingers/condensers, and barometer shall be as specified in US EPA Method 5, Section 2.1. Note that an equivalent condenser may be used in place of the impinger train.

(7) Sample Recovery Accessories: As specified in Section 2.2 of US EPA Method 5.

(8) Analytical Accessories: As specified in US EPA Method 5, Section 2.3.

C. Reagents:

(1) Sampling:

(2) Filters: Glass fiber type, having high efficiency for collecting small particles (99% or higher efficiency for particles 0.3 microns or larger in diameter). Cambridge Media CM-114 or Gelman Type A filters are acceptable types.

(3) Other Sampling Reagents: As specified in US EPA Method 5, Section 3.1.

(4) Sample Recovery and Analytical Reagents: Acetone and water, as specified in Sections 3.2 and 3.3 of US EPA Method 5.

D. Sampling Procedure:

(1) Selection of Sampling Site and Sampling Points: The sampling site is preferably located in a vertical duct or stack, at least eight stack diameters downstream and two diameters upstream of a major disturbance (bend, expansion, contraction, or visible flame). In large ducts (of 20 feet or greater diameter), a distance five diameters downstream of a disturbance will be considered adequate, providing the velocity traverse does not show the flow to be highly irregular. Under these recommended conditions, a single sampling point is considered to be adequate (See Industrial Gas Cleaning Institute, Test Procedures for Gas Scrubbers, Publication No. 1, p. 6): This point shall be located between 0.2 and 0.5 of the diameter from the outside toward the center of the stack, preferably at a point whose velocity approximates the average velocity of the flue gases. For conditions which do not meet the criteria given above, additional sampling points must be considered and will be determined as agreed upon between the coal-burning equipment operator and the Department.

(2) Determination of Stack Pressure, Temperatures, Moisture and Distribution of Velocity Heads: Prior to actual sampling for particulates, a preliminary survey of stack pressure, temperature, moisture content, and velocity distribution shall be made to assess overall sampling conditions and establish isokinetic sampling velocities.

(a) Stack Pressure and Temperature: Stack pressure shall be obtained at one or more points at the sampling station using a water-filled U-tube manometer to sense pressure from a hole in the side of the stack or duct to within 0.1 in water. Temperatures shall be determined from a thermocouple (or equivalent device) attached to the pitot tube, capable of measuring to within 1.5% of the minimum absolute stack temperature.

(b) Distribution of Velocity Heads: The US EPA Method 1 ( 40 CFR, Part 60, Appendix A) shall be used as a general guide in determining the number and distribution of pitot tube traverse points. US EPA Method 2 ( 40 CFR, Part 60, Appendix A) shall be used as a guide in selection of pitot tube equipment, procedure for making and recording measurements, and calibration of the instrument. In calibration, the procedure shall be modified in that the pitot tube to be used in testing shall be mounted on the probe and the probe shall have attached to it a 1/4-inch sampling nozzle so that the arrangement is similar to that used in testing. A complete velocity traverse shall be done each day of testing.

(c) Moisture Determination: Moisture content of the gas stream is determined by extracting a measured quantity of gas from the stack, condensing the moisture in an external condenser (or in the impingers), and measuring the volume of condensate. A single, preliminary measurement shall be made using either the stack sampling train or a simplified apparatus consisting mainly of a filter, condenser, pump, and dry gas meter. If liquid drops are present in the gas stream, proceed as follows: Assume the stream to be saturated, determine the average stack gas temperature from the data obtained in subparagraph (a) of paragraph (2) of subsection D of 20.2.14.301 NMAC above, and use a psychometric chart with appropriate altitude correction along with steam tables to calculate the approximate percentage of moisture. A further determination of moisture content is made as a part of the particulate sampling as described below.

(3) Preparation of Collection Train: Check to see that the probe, nozzle, etc., are clean and that there is sufficient ice to fill the ice bath, place 100 ml. of water in the first two impingers, leave the third impinger empty, and place approximately 200 g. of preweighed indicating silica gel in the fourth impinger. Complete the preparation by desiccating the filter, checking the train for leaks and adjusting the probe heater, generally as specified in US EPA Method 5, Section 4.1.2. To establish near isokinetic sampling conditions at the start of testing, the desired flowrate through the particle separator is corrected to stack conditions and the desired sample nozzle size is calculated. To do this record the temperature of the container surrounding the particle separator. Find this temperature in the abscissa of the graph in Figure 3 (20.2.14.304 NMAC), go up to the curve and read the correction factor on the ordinate of the graph. Multiply the correction factor by 2 microns and obtain the temperature corrected aerodynamic diameter. Locate the corrected aerodynamic diameter on the abscissa of the graph on Figure 4 (20.2.14.305 NMAC), go up to the curve and read on the ordinate the flowrate needed to maintain an impaction efficiency of 50% on plate #4. Correct this flowrate to stack conditions by adjusting for the difference in particle separator temperature and stack temperature. Using the equation Q = VA where Q = volumetric flowrate through the separator adjusted to stack temperature (cfm), V = velocity of the stack gas at the point in the stack where the sampling is to take place (fpm) and A is area of the nozzle (sq. ft.) calculate the desired sampling nozzle diameter. Attach a nozzle to the probe that matches this calculated diameter within 1%. To establish at the start of testing the correct gas flow through the separator, using the dry gas meter, correct the desired flowrate through the separator to meter conditions by correcting for the difference in temperature between the separator and the dry gas meter and subtract out that portion of the gas volume which will be condensed in the impingers.

(4) Particulate Train Operation: To begin sampling, position the nozzle at the selected point in the stack with the nozzle tip pointing directly into the gas stream. Immediately after, start the pump and adjust the dry gas meter to the flowrate calculated in paragraph (3) of subsection D of 20.2.14.301 NMAC. Sample for at least 5 minutes and then record the temperature of the gas on the outlet end of the separator. If the temperature is different from that of the container surrounding the separator readjust the dry gas meter flowrate by repeating the steps described in paragraph (3) of subsection D of 20.2.14.301 NMAC using Figures 3 (20.2.14.304 NMAC) and 4 (20.2.14.305 NMAC) excluding the step used in calculating nozzle diameter. Continue the run until 30 standard cubic feet (70 degrees Fahrenheit, 29.92 inches Hg) have been drawn through the sampling train. For each run record the required data on a sheet such as the one shown in Figure 5-2 of US EPA Method 5 and include the temperature monitored at the outlet of the separator. Record the data after every 5 minutes of testing. At the end of the run, turn off the pump and record the final readings. Remove the probe and nozzle from the stack. Remove the filter from the separator and place in a container. Repeat the sampling procedure until three runs have been obtained. Desiccate the filters for at least 24 hours and weigh to the nearest 0.5 mg in a room where the relative humidity is less than 50%.

E. Calibration: Use approved methods and equipment for calibration of the particle separator, orifice meter, pitot tube, temperature sensors and dry test meter. Recalibrate after every third test or three months whichever comes first except for the particle separator which shall be recalibrated as agreed upon between the owner or operator of the coal burning equipment and the Department.

F. Calculations: After completing the test series, average the dry gas meter temperatures and average orifice pressure drops, correct the sample volume measure to standard conditions and calculate the water vapor and moisture content. Calculate the concentration of particulate matter in the stack gas in pounds per standard cubic foot on a dry basis by using equation 5-5 given in Section 6.6.2 of US EPA Method 5. Use only the weight of the particulate collected on the filter. Using the stack volumetric flowrate corrected to standard conditions on a dry basis calculate the emission rate in pounds per hour. Using the average heat input to the coal burning equipment during the time of testing, in million Btu per hour, calculate the emission rate in pounds per million Btu. Average the emission rate for the three runs.

G. Acceptable results: Validity of each run shall be determined by calculating the actual flow through the particle separator from the recorded data. If the flowrate is within 10% of the ideal flow calculated from Figure 4 (20.2.14.305 NMAC) the run will be considered valid. Deviations from isokinetic sampling rate shall not invalidate the test.

N.M. Admin. Code § 20.2.14.301

11/30/95; 20.2.14.301 NMAC - Rn, 20 NMAC 2.14.301 10/31/02