E AP Project Summary

United States

Environmental Protection

Agency

Minipilot Solar System:

Design/Operation of System

and Results of Non-Solar

Testing at MRI

Risk Reduction

Engineering Laboratory

Cincinnati, OH 45268

Research and Development

A Minipilot Solar Reactor System

(MSRS) with liquid organic feed was

designed, constructed, and tested without solar input (the solar tests were to

be done later at DOE’s National Renewable Energy Laboratory). The nonsolar tests were done to determine

whether use of EPA’s sampling and

analysis methods would allow

quantitation of the expected significantly lower organic emissions when

the MSRS is operated with solar input.

Results of the 10 tests showed that it

should be possible to determine if there

is a significant reduction in emissions

(>3X) when operating with solar input.

Such reduction in the emissions should

be determinable for two of the principal constituents contained in the synthetic feed liquid (CCl4 and

dichlorobenzene), for both the volatile

and semivolatile products of incomplete

combustion (PICs), and for dioxins and

furans. But reductions are probably not

determinable for the other two feed constituents (toluene and naphthalene).

Results also showed that a three-fold

reduction in volatile PICs occurred in

both single-chamber tests when an artificial UV light was utilized.

This Project Summary was developed

by EPA’s Risk Reduction Engineering

Laboratory, Cincinnati, OH, to announce

key findings of the research project

that is fully documented in a separate

report of the same title (see Project

Report ordering information at back).

Introduction

A Tri-Agency effort was initiated in 1991

to develop solar technology for the destruction of hazardous wastes. The three

Agencies are EPA (RREL, the Risk Reduction Engineering Laboratory), DOE

(NREL, the National Renewable Energy

Laboratory), and DOD (USAEC, the U.S.

Army Environmental Center). As part of

the Tri-Agency effort, EPA’s RREL set out

to design, construct, and test an MSRS

with liquid organic feed. The system was

designed to enable the study of the destruction of organic compounds and the

emission of PICs when combustion of the

liquid organic feed was augmented with

concentrated solar input.

This project did not involve use of solar

energy for desorption of organics from

soil. Rather, it was directed to the use of

solar energy for destruction of organics

that would be desorbed from soil by conventional low-temperature thermal desorption, with recovery of the desorbed

organics in liquid form prior to their solar

destruction. Advantages of this concept

are that it utilizes conventional desorption

equipment and enables soil desorption

operations to be continuous (that is, independent of solar availability). Also, this

concept enables the solar destructor to be

relatively small since it needs to process

only the amount of organics recovered as

liquid from the soil desorption operations.

Testing of the MSRS was intended to

include the determination of the degree of

destruction of principal organic hazardous

EPA/600/SR-94/027 April 1994

Paul Gorman, Ed Ball, John James and Pam Murowchick
2

constituents (POHCs) and the emission of

PICs, when operating with concentrated

solar input using facilities at DOE’s National Renewable Energy Laboratory. It

was first necessary, however, to conduct

tests without solar input to determine if it

would be possible to quantify significantly

lower levels of emissions that might be

provided by solar input.

The system has not yet been tested

with solar input, but testing without solar

input has been completed. Those “nonsolar” results are summarized here, along

with results from tests done with the input

of artificial ultraviolet (UV) light.

Methodology

The MSRS was designed to operate in

either of two modes: single or duel chamber. In the single-chamber mode, the liquid feed is combusted in one chamber

that is equipped with a quartz window for

the concentrated solar rays to enter. In

the dual-chamber mode, the liquid is combusted in one chamber and the gases

then enter the second chamber which is

equipped with the quartz window.

The entire system consisted of many

components including the feed and control of liquid organic and combustion air,

and effluent gas monitoring and cleanup

(see Figure 1). It was fully equipped with

process monitoring instruments, flame detectors and other safety shutdown interlocks, continuous emission monitoring of

CO, 02

, and THC, and computerized data

logging and control.

The design of the system was based on

a liquid organic feed rate of 11 g/min. and

an air feed rate of 10 ft3/min. Each reactor

chamber was 10.5 in. inner diameter by

36 in. long with approximately 4-in.-thick

internal insulation and 4-in.-thick external

insulation (see Figure 2). Operating temperatures could be varied over a range of

1400° to 2000°F.

The composition of the synthetic liquid

organic feed to be used in most of the

non-solar and solar testing was selected

by the Tri-Agency group. Its composition

was:

POHC/Fuel Oil Blend

• No. 2 fuel oil 40%

• o-Dichlorobenzene (DCB) 40%

• Carbon tetrachloride (CCl4) 10%

• Naphthalene 5%

• Toluene 5%

100%

After initial operation of the system and

preliminary testing with an on-line gas chromatograph/electron capture detector, tests

were conducted using EPA Methods 0030

and 0010 (volatile organic sampling train

[VOST] and modified Method 5 [MM5]) to

quantify the emissions of the POHCs listed

above and the emission of PICs. As noted

previously, the primary purpose of these

tests was to measure emissions in the

non-solar mode in order to determine if

significantly lower emissions could be

quantified when operating with solar input. This was determined by comparing

the measured emissions with the detection limits of the methods and blank levels.

Results

A series of 10 tests, without solar input,

was carried out using the EPA methods

(VOST and MM5). This series included

tests in both the single- and dual-chamber

modes at two waste feed and air input

flow rates (referred to as “low flow” and

“high flow”). Four of these tests were done

with the input of UV light to simulate the

solar tests that were to follow at DOE/

NREL’s “High-Flux Solar Facility” located

in Golden, CO. All tests involved analysis

of samples for POHCs and PICs, and

some tests also included the analysis of

dioxins/furans.

Results from the 10 tests are summarized in Table 1. Runs 35, 36, 39, and 40

of Table 1 show the four UV-light tests.

These can readily be compared with the

six “conventional incineration” tests also

shown in the table.

Conclusions

Major conclusions drawn from the test

results were:

• Destruction/removal efficiency for the

four POHCs were all above 99.999%

in these non-solar tests.

• Based mainly on the comparison of

measured emissions with blank levels, it will be possible to quantify a

significant decrease in emissions of

volatile and semivolatile PICs and two

of the POHCs (CCl4

 and DCB) when

the solar (“on-sun”) tests are done at

NREL. It will not be possible, however, to quantify any significant decrease in emissions of the other two

POHCs (toluene and naphthalene).

• Tests with artificial UV light indicated

a significant decrease in emissions of

volatile PICs when operating in the

single-chamber mode; however,

these tests did not show a significant

decrease for semivolatile PICs, nor

for any of the four POHCs tested.

The full report was submitted in fulfillment of Work Assignment No. 18 of EPA

Contract No. 68-DO-0137 by the Midwest

Research Institute (MRI) of Kansas City,

MO under the sponsorship of the U.S.

Environmental Protection Agency.

Compressed air

Liquid organic feed 1st chamber

2nd chamber

Gas

cooler

CW

Water

separator

Alumina

NaOH

pellet bed

Carbon

Gas pump bed

Gas effluent

discharge

Quartz

window

Figure 1. Simplified schematic diagram of Minipilot Solar Reactor System.
3

18.000 DIA.

Fuel injection

and access ports

4 inch

Flange

3.625 inch thick

insulation 36.000

10.500 DIA.

flame detector port

1 inch flange

4 inch flange

2.026

13.875 dia. quartz window for solar

or UV input

Note: All dimensions are in inches

Figure 2. Solar detoxification reactor - section view.
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Table 1. Summary of Results from Minipilot Solar Reactor Runs 31 through 40

Single chamber Dual chamber

Units Run 31 Run 34 Run 36* Run 32 Run 33 Run 35* Run 38† Run 37† Run 39† Run 40

Operating Conditions Low flow Low flow Low flow High flow High flow High flow Low flow High flow High flow High flow

 Secondary airflow dscf/min 4.14 4.23 4.29 7.84 7.44 7.62 4.38 7.64 7.77 7.88

 Liquid organic flow rate mL/min 4.10 4.62 4.22 7.85 7.45 8.17 4.10 7.77 7.69 7.21

 UV light Yes or No No No Yes No No Yes No No Yes Yes

 O2 level % 9.3 9.0 3.2 12.3 11.9 7.9 4.2 8.7 6.7 11.8

 Residence time sec 7.1 7.0 6.8 4.0 4.2 4.0 13.3 7.8 7.8 8.9

DREs

 Carbon tetrachloride % 99.999968 99.999963 99.999970 99.999811 99.999910 99.999829 99.999981 99.999949 99.999914 99.999546

 Toluene % 99.999951 99.999926 99.999950 99.999905 99.999938 99.999966 99.999965 99.999935 99.999941 99.999952

 Dichlorobenzene % 99.9999975 99.9999965 99.9999950 99.9999924 99.9999944 99.9999977 99.9999976 99.9999960 99.9999988 99.999991

 Naphthalene % 99.99966 99.99940 99.99926 99.99943 99.99949 99.99952 99.99949 99.99935 99.99962 99.99961

Volatiles(amount of one trap pair)

 Carbon tetrachloride ng 21.9 37.2 25.2 124.9 46.9 158.7 13.6 40.9 125.8 230.0

 Toluene ng 5.6 61.2 25.4 23.5 41.6 19.2 15.1 22.0 27.6 14.7

 Total PICs ng 4,685 6,862 1,376 4,824 5,827 1,823 779 895 1,079 1,069

 Volume sampled L 18.12 18.80 18.64 20.87 18.76 18.94 19.20 19.29 19.16 19.45

 POHC and PIC

 concentration‡ μg/dscm 260 370 76 238 315 106 42 50 64 68

Semivolatiles

 Dichlorobenzene μg 0.22 0.36 0.36 0.86 0.68 0.30 0.21 0.45 0.15 1.04

 Naphthalene μg 3.70 7.72 6.75 8.00 7.72 7.89 5.55 9.09 5.91 5.75 Total PICs μg 1,560 3,248 2,334 4,018 2,014 3,714 2,148 3,579 2,331 14,271

 MM5 sample volume dscm 0.617 0.612 0.494 0.751 0.815 0.824 0.604 0.726 0.801 0.802

 POHC and PIC

 concentration§ μg/dscm 2,535 5,320 4,739 5,362 2,481 4,517 3,566 4,943 2,918 17,803

Dioxins and Furans

 Dioxins μg -- 0.00161 -- -- 0.00316 -- -- 0.00655 0.01082 0.00825

 Furans μg -- 0.00871 -- -- 0.02102 -- -- 0.04470 0.07802 0.04134 Total μg -- 0.01032 -- -- 0.02508 -- -- 0.05125 0.08884 0.04759

Blanks

 Carbon tetrachloride ng <4.0 <4.0 6.5 <4.0 <4.0 <4.0 <4.0 <4.0 <4.0 <4.0

 Toluene ng <4.0 <5.2 5.8 <4.0 <4.0 <4.4 7.6 <4.0 7.7 <6.0

 Volatile PICs ng 85

 Dichlorobenzene μg 0.06

 Naphthalene μg 4.32 Semivolatile PICs μg 225

 Dioxin μg 0.000618

 Furan μg 0.0000776

* Auxiliary fuel (fuel oil) was fired in Runs 35 and 36 to maintain operating temperature during these tests with UV light in the single chamber mode.

† Propane was fired in the second chamber in Runs 37, 38, and 39 to maintain the operating temperature in the second chamber.

‡ Volatile POHC/PIC concentrations range from 42 to 370 μg/dscm, which is equivalent to 0.010 to 0.088 ppm, (assuming an approximate average MW of 100).

§ Semivolatile POHC/PIC concentrations range from 2,481 to 17,803 μg/dscm, which is equivalent to 0.40 to 2.88 ppm, (assuming an approximate average MW of 150).
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Paul Gorman, Ed Ball, John James and Pam Murowchick are with Midwest

Research Institute, Kansas City, MO 64110

C.C. Lee is the EPA Project Officer (see below).

The complete report, entitled "Minipilot Solar System: Design/Operation of

System and Results of Non-Solar Testing at MRI," (Order No. PB94-

152238AS; Cost: $27.00, subject to change) will be available only from:

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22161

Telephone: 703-487-4650

The EPA Project Officer can be contacted at:

Risk Reduction Engineering Laboratory

U.S. Environmental Protection Agency

Cincinnati, OH 45268

BULK RATE

POSTAGE & FEES PAID

EPA

PERMIT No. G-35

United States

Environmental Protection Agency

Center for Environmental Research Information

Cincinnati, OH 45268

Official Business

Penalty for Private Use

$300

EPA/600/SR-94/027