Reference methods: releases of vinyl chloride from plants, chapter 2


Part 1: Sampling

Method S-2: Sampling for the determination of reactor opening releases from polyvinyl chloride plants

S-2.1 Scope

This method applies to the sampling of the gases contained in a PVC polymerization reactor immediately after a reactor has been opened.

S-2.2 Apparatus

S-2.2.1 Sampling Train

(See Figure S-2-1)

S-2.2.2 Sampling Line

The sampling line shall be connected to the sampling train using the minimum length of Teflon® tubing. Use a clean piece of Teflon® tubing to sample each opened reactor. The sampling line shall be long enough to reach the bottom of the reactor being tested. The sampling train is to be located as close as is practical to the reactor.

S-2.2.3 Rotameter

A rotameter capable of measuring flows in a range from 0 to 0.5 litres/min is required. The rotameter shall have a measurement accuracy of within ±5% of full scale.

S-2.2.4 Pump

An intrinsically safe sampling pump shall be used to fill the sampling bag. The pump shall have both inlet and exhaust ports and a capacity of at least 200 mL/min.

S-2.2.5 Needle Valve

A needle valve is used to adjust the sampling rate as indicated on the rotameter.

S-2.2.6 Quick-Connect

A male and a female stainless steel quick-connect, with ball checks, are required to connect the sampling bag to the sampling train and to the sample recovery loop.

S-2.2.7 Sampling Bag

The gas sample shall be collected in a Tedlar® or aluminized Mylar® sampling bag. The capacity of the sampling bag shall be adequate to contain the required total sample volume, based on the following calculation -- sampling rate multiplied by duration --, and be at least half full at the completion of sampling.

S-2.3 Procedures

Assemble the sampling train as shown in Figure S-2-1 but do not connect the bag. Leak-check and purge the bag according to S-1.4 before use. A leaking sampling bag shall not be used.

Verify that all connections are tight. Open the manway lid just enough to permit the insertion of the sampling line to within 30 cm of the bottom of the reactor. The line end shall not touch the bottom of the reactor chamber. If water is present at the bottom of the reactor, place the end of the sampling line above the water level. Close the lid, leaving only a gap to enable movement of the sampling line. If a sampling location exists at the top of the reactor that allows for the insertion of a sampling line into the reactor for the collection of the required gas samples, then that port may be used in lieu of opening of the reactor manway lid. Start the pump and purge the train at a sampling rate of at least 200 mL/min. The purge duration must allow at least three gas volume exchanges through the sampling train. Stop the pump.

Connect the sample bag, start the pump, and begin sampling at a rate of at least 200 mL/min.

The sample shall be obtained by sampling for five minutes at each of the three following points in the reactor: within 30 cm of the bottom, at the centre of the reactor, and within 30 cm of the lid of the reactor.

Sampling shall be continuous throughout the 15-minute sampling period and shall begin within 10 minutes of the reactor being opened.

Obtain the data set out on Form S-2.2and record them on that form or in the format of the sampler's choice.

S-2.4 Sample Storage and Analysis

Sampling bags shall be stored out of direct sunlight. For sample tracking, assign a unique identifier to each bag sample submitted for analysis. Analysis of a sample shall be done using Method A-1 contained in Part 2 of this Reference Method.

S-2.5 Calculations

Sample test data may be recorded in the units for which the sampling equipment is designed. However, if those units are different than those stipulated in this sampling method, they shall be converted to the units used in the equations of this sampling method.

S-2.5.1 Equations

(See S-2.5.2 for nomenclature)

Mass Releases per Unit Production

The release rate of VCresulting from a reactor opening shall be calculated using equation S-2.1:

Equation S-2.1

S-2.5.2 Nomenclature

C b
concentration of VCin the sample, ppm (v/v) (as determined by equation A-1.3 of A-1.6.3 within Part 2 of this Reference Method)

ER VC/ PVC
mass release rate of VC per production of PVC, kg of VC per 100 kg of PVC

V r
reactor volume, m 3

W
total weight of PVC resin produced since last opening, in 100 kg increments (e.g. if the production is 300 kg, then W equals 3)

2.56 × 10 -6
conversion factor, ppmof VC to kg/m 3 at 25°C and 101.3 kPa

Figure S-2-1: Sampling train for measuring reactor opening releases

Figure S-2-1: Sampling train for measuring reactor opening releases

Form S-2.2: Measurement of reactor opening releases

Plant:

____________________________

Date:

____________________________

Date of last Opening:

____________________________

Sample Identifier Number:

____________________________

Sample Taken by:

____________________________



Local Time Sampling Probe Location Sampling Time (min) Sampling Rate (mL/min)
  Bottom    
  Middle    
  Top    



Time Reactor Opened:

____________________________

Reactor Volume (m3):

____________________________

Weight of Resin Produced Per Batch (kg):

____________________________

Number of Batches Since Previous Opening:

____________________________

Plant name and street address of site where sample was collected:

____________________________



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