Marine exhaust gas cleaning system

Abstract

A marine exhaust gas scrubbing device including an enclosure having a first end and a second end, an exhaust gas inlet, at least one quencher, at least one pre-treater, at least one venturi component including a venturi inlet and a venturi outlet, an impingement basket, at least one demister, an exhaust gas outlet, and a receiver, and a process for scrubbing a marine exhaust gas including cooling the exhaust gas, pre-treating the exhaust gas, washing the exhaust gas, mixing the exhaust gas and exhausting the scrubbed exhaust gas.

Claims

1. A marine exhaust gas scrubbing device comprising: a) an enclosure having a first end and a second end; b) an exhaust gas inlet proximate said first end for accepting a high temperature exhaust gas comprising sulfur dioxide and particulate matter; c) at least one quencher proximate the exhaust gas inlet for cooling the high temperature exhaust gas with at least one quenching fluid to give a cooled exhaust gas; d) at least one pre-treater for pre-treating the cooled exhaust gas with at least one pre-treating fluid to give a pre-treated exhaust gas; e) at least one venturi component comprising a venturi inlet for accepting the pre-treated exhaust gas and a venturi outlet for washing the pre-treated exhaust gas with at least one washing fluid to give a washed exhaust gas containing a plurality of washing fluid droplets and conveying the washed exhaust gas to the venturi outlet; f) an impingement basket proximate the venturi outlet for providing additional mixing of the washed exhaust gas with the washing fluid; g) at least one demister for removing the plurality of washing fluid droplets from the washed exhaust gas to form a demisted exhaust gas; h) an exhaust gas outlet at said second end for exhausting said demisted exhaust gas; and i) a receiver for receiving the at least one quenching fluid, the at least one pre-treating fluid and the at least one washing fluid.

2. The device of claim 1 wherein the at least one quenching fluid, the at least one pre-treating fluid and the at least one washing fluid are basic.

3. The device of claim two wherein the at least one quenching fluid, the at least one pre-treating fluid and the at least one washing fluid comprise an aqueous alkali metal hydroxide solution selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, an aqueous alkaline earth metal hydroxide solution selected from calcium hydroxide, magnesium hydroxide, and combinations thereof.

4. The device of claim 1 wherein the at least one venturi component is a concentric venturi further comprising a convergent-divergent passageway joining the venturi inlet with the venturi outlet.

5. The device of claim 3 wherein the alkali metal hydroxide is sodium hydroxide.

6. The device of claim 1 wherein the at least one quenching fluid, the at least one pre-treating fluid, the at least one washing fluid have a pH of from about 8 to about 12.

7. The device of claim 1 wherein the enclosure, the at least one quencher, the at least one pre-treater, the at least one venturi, the impingement basket and the at least one demister are constructed of material resistant to a temperature of up to about 300 C.

8. The device of claim 1 further comprising a generator for generating the at least one quenching fluid, the at least one pre-treating fluid and the at least one washing fluid.

9. The device of claim 1 further comprising a distributor for distributing the at least one quenching fluid, the at least one pre-treating fluid and the at least one washing fluid.

10. The device of claim 1 further comprising a collecting receiver for receiving the at least one quenching fluid, the at least one pre-treating fluid and the at least one washing fluid.

11. The device of claim 1 further comprising a cooler for cooling the at least one quenching fluid, the at least one pre-treating fluid and the at least one washing fluid.

12. The device of claim 1 further comprising a cleaner for cleaning the at least one quenching fluid, the at least one pre-treating fluid and the at least one washing fluid.

13. The device of claim 1 wherein said device is closed-loop.

14. A process for scrubbing marine exhaust gas comprising the steps of: a) providing a high temperature exhaust gas comprising sulfur dioxide and particulate matter; b) cooling the high temperature exhaust gas using a quenching fluid to give a cooled exhaust gas; c) pre-treating the cooled exhaust gas using a pre-treating fluid to give a pre-treated exhaust gas; d) washing the pre-treated exhaust gas using at least one venturi component comprising a venturi inlet for accepting the pre-treated exhaust gas and a venturi outlet for washing the pre-treated exhaust gas with a washing fluid to give a washed exhaust gas containing a plurality of washing fluid droplets and conveying the washed exhaust gas to the venturi outlet; e) mixing the washed exhaust gas with the washing fluid using an impingement basket; f) removing the plurality of washing fluid droplets from the washed exhaust gas to form a demisted exhaust gas; g) exhausting the demisted exhaust gas; and h) capturing the quenching fluid, the pre-treating fluid, and the washing fluid.

15. The process of claim 14 wherein the quenching fluid, pre-treating fluid and washing fluid are basic.

16. The process of claim 15 wherein the quenching fluid, pre-treating fluid and washing fluid comprises an aqueous alkali metal hydroxide selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, an aqueous alkaline metal earth hydroxide selected from calcium hydroxide, magnesium hydroxide, and combinations thereof.

17. The process of claim 16 wherein the alkali metal hydroxide is sodium hydroxide.

18. The process of claim 14 wherein the quenching fluid, the pre-treating fluid, and the washing fluid have a pH of from about 8 to about 12.

19. The process of claim 14 further comprising a process for generating the quenching fluid, the pre-treating fluid and the washing fluid.

20. The process of claim 14 further comprising a process for distributing the quenching fluid, the pre-treating fluid and the washing fluid.

21. The process of claim 14 further comprising a process for collecting the quenching fluid, the pre-treating fluid and the washing fluid.

22. The process of claim 14 further comprising a process for cooling the quenching fluid, the pre-treating fluid and the washing fluid.

23. The process of claim 14 further comprising a process for cleaning the quenching fluid, the pre-treating fluid and the washing fluid.

24. The process of claim 14 wherein said process is closed-loop.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a schematic of one embodiment of the present invention.

(2) FIG. 2 shows a schematic of another embodiment of the present invention.

(3) FIGS. 3, 3 A-A and 3 B-B show a schematic of an embodiment of the present invention with two venturi components.

(4) FIG. 4 shows a schematic of the embodiment of the present invention with a venturi component with rotation flow blades.

(5) FIG. 5 shows a top view cut away of the embodiment of the present invention with a divided exhaust gas entry system.

(6) FIG. 6 demonstrates the results for Tests B and F showing the systems capability of SO.sub.2 removal and its correlation to the venturi flow rate (gpm).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) The marine exhaust gas scrubbing device in one embodiment is installed in-line in the funnel of the marine exhaust gas system in lieu of the existing exhaust silencer. The system is manufactured from 316L stainless steel for resistance to sodium hydroxide and seawater, and quenching, pre-treating and washing fluids have a pH of 12 (10 mmol/l) or less. This pH level is generally considered as equivalent to soapy water and is classified as non-hazardous and non-corrosive. The device is preferably designed so that there is no standing seawater/quenching/pre-treating/washing fluid in order to reduce and/or prevent corrosion of the stainless steel.

(8) With reference to FIG. 1, the marine exhaust gas scrubbing device 100 contains an exhaust inlet 110, an exhaust outlet 120, a quencher 500 to cool the incoming hot exhaust gas 111, a pre-treater 600 to pre-treat the quenched exhaust gas 112, a convergent-divergent venturi 300, having a convergent zone 301, a divergent zone 302, and a convergent-divergent passageway 303. The convergent zone 301 contains a washer 320 further to mix the pre-treated exhaust gas 113 and a venturi washdown 310 to remove soot and solid material from the venturi, an impingement basket 700 for further mixing allowing for the separation and collapse of the bubbles formed during operation of the marine exhaust gas scrubbing device 100, a demister 420 to remove fluid droplets from the treated exhaust and an exit space washdown 410. Excess quenching, pre-treating and washing fluid is collected by the drain 200. The unit also includes a demister soot cleaning washdown nozzle 400.

(9) With reference to FIG. 2, an alternate embodiment of the marine exhaust gas scrubbing device 100 contains an exhaust inlet 110, and exhaust outlet 120, a quencher/pre-treater 550, a butterfly valve 130, a venturi 300 having a conical reducer 330 and containing a washer 320 and a demister 400. Excess quenching, pre-treating and washing fluid and washed solids are collected by the drains 200 which empty into sump 250.

(10) With reference to FIGS. 3, 3 A-A and 3 B-B, a marine exhaust gas scrubbing device 100 is shown having two venturi components 300 in parallel. FIG. 3 A-A provides the flowpath of the exhaust gas from the exhaust gas inlet 110, up the inlet side 121 of the device 100 into the two venturi components 300 out the venturi outlet 304, up the outlet side 122 and out the treated exhaust gas outlet 120.

(11) With reference to FIG. 4, the convergent zone 301 is shown with rotational flow blades 800 along the inside wall of the upper portion of the convergent zone 301. The flow blades 800 are angled (helical in configuration) to promote rotational flow of the exhaust gas into the convergent-divergent passageway 303. Although helical blades are shown herein, the rotational flow may be any surface structure along the inside of the convergent zone 301 that will promote rotational flow. Examples include but are not limited to, surface beads, surface impressions, surface etchings, ribs and combinations thereof.

(12) With reference to FIG. 5, there is provided top cutaway view of the exhaust gas inlet 110 modified such that the exhaust gas 111 is divided into two streams before entering the inlet side 121 of the scrubber device 100, resulting in a rotational flow of the exhaust gas and a turbulent zone in the scrubber.

(13) Drains

(14) The drain 200 from the marine exhaust gas scrubbing device 100 of the present invention is designed for gravity flow of 125% of the maximum pump flow through the nozzles of the device into the collector. In a most preferred embodiment the device has two separate compartments for the pre-treatment and primary treatment. Each compartment has its own drain and is designed for maximum flow of the nozzles.

(15) The marine exhaust gas scrubbing device of the present invention can also operate in dry-mode wherein no quenching, pre-treating, washing, mixing or demisting steps are employed. The device is constructed of a material that can resist in one embodiment an exhaust temperature of 265 C. The device, when in full operation, also has a backpressure less than about 150 mm (dry) and less than about 60 mm (wet). The complete unit including the exhaust piping and other equipment is below about 350 mm water column backpressure limit total for marine engines.

(16) Optional Access for Inspection and Maintenance

(17) Optionally included in the marine exhaust gas scrubbing device of the present invention are three external access panels in the side of the device and one internal access panel in the divider plate between the exhaust inlet 110 and exhaust outlet 120. Two of the external access panels are located above the demister 400 for demister installation and access to the upper portion of the exhaust outlet end of the device. The third external access panel is located on the lower portion of the exhaust outlet of the device for access to the interior of the device, the impingement basket 700 and primary drain.

(18) The exhaust inlet side 121 of the marine exhaust gas scrubbing device is accessed from the exhaust outlet side 122 by an access panel in the vertical divider 123 between the exhaust inlet and exhaust outlet sides of the device for access to the exhaust inlet elbow, the inlet drain and the nozzle headers. The spray nozzle lances are also accessible by removing the headers from flanged penetrations on the exhaust inlet side of the device. Inspection points are also provided in the access panel or the device body for visual inspection and temporary testing or sampling of the exhaust gas stream.

(19) Soot Cleaning

(20) Optionally, to insure minimal soot build-up in the device, the wetted portions of the internal walls of the device are continually washed through the pre-treatment 600 and primary 500 nozzle systems. In particular the nozzles 405 serve as soot cleaning nozzles as well. Additional washdown spray nozzles 310 are also provided in the top of the venturi component 300, below the demister 420 (see 400) and in the exhaust outlet 120 above the demister (see 410). These nozzles may be operated as needed to wash soot from these portions of the device.

(21) Demister and Exhaust Outlet

(22) Proximate the exhaust outlet 120 of the marine exhaust gas scrubbing device 100 of the present invention are three pass chevron-type demisters 420 designed to eliminate mist having a preferable diameter of about 25 microns. The demisters are preferably fabricated from 316L stainless steel and are installed in the device on a Z-shaped divider panel 420 approximately halfway up the exhaust outlet side 122. The demisters are installed through access panels in the sides of the device. The demisters are designed with a maximum velocity of about 5 meters per second and a maximum pressure drop of about 65 mm water column. The demister area is also fitted with an optional washdown spray system 400 to wash any soot or dried sodium hydroxide or salts from the demister vanes.

(23) While the water droplets are largely eliminated by the demisters 420, the exhaust gas exiting the marine exhaust gas scrubbing device is generally saturated at a temperature range of from about 35 C. to about 50 C. Some water vapour is expected to condense on the inside walls of the exhaust outlet compartment and elbow. The exhaust outlet and elbow are constructed from 316L stainless steel to prevent any problems with corrosion in these areas and any water condensed is expected to drain down through the demisters 420 and the demister support plates into the primary device drain 200. The saturated exhaust forms a white plume as the exhaust stream contacts the outside air.

(24) Quenching, Pre-Treating and Washing Fluid

(25) In one embodiment, the quenching, pre-treating and washing fluids are a mixture of seawater and aqueous sodium hydroxide. The sodium hydroxide is added to maintain maximum alkalinity between about pH 8 (0.1 mmol/l) and about pH 12 (10 mmol/l) and has a maximum sodium hydroxide concentration of about 0.04% by weight. The fluid solution at the maximum pH would be equivalent to soapy water and not considered hazardous to personnel or equipment. By-products of the expected chemical reactions are not considered hazardous or corrosive. The particulates cleaned from the marine exhaust gas may contain heavy metals and oil which should be considered to require standard handling as for used engine oil, or similar, but are not acutely hazardous to personnel or corrosive to the device components.

(26) The quenching, pre-treating and washing fluids are cooled by a seawater heat exchanger so that it is at a target of about 35 C. for the spray systems. The maximum operating temperature of the fluid is restricted to about 65 C. in order to limit evaporation and to ensure that it remains within the operating temperatures of the composite materials of the distribution means piping.

(27) The fluid collects sulfur dioxide, other gases and particulate matter from the marine exhaust gas stream. The sulfur dioxide is neutralized by the sodium hydroxide and the resulting particulate matter along with other solids and salt precipitate is cleaned by the cleaning means to ensure the fluid remains at 5% solids or lower.

(28) The fluids are contained within the unit and thus the unit is closed-loop.

(29) Fluid Piping, Valve and Pump Materials

(30) The materials selected for the marine exhaust gas scrubbing device 100 are generally based on resistance to concentrated seawater, with additional consideration for any materials which may react with the sodium hydroxide. Suitable materials for the fluid solution include copper nickel (70/30), bronze, nickel aluminum bronze, duplex stainless steel, alloy 20, nickel alloys and glass reinforced epoxy (GRE). Suitable materials for a diluted sodium hydroxide solution are selected based on the Handbook of Corrosion Data and include copper nickel (70/30), bronze, 316 stainless steel, duplex stainless steel, alloy 20, AL6XN, Hastelloy and GRE. The recommended material for seawater and sodium hydroxide solution are based primarily on resistance to seawater and include copper nickel (70/30), bronze, nickel aluminum bronze, duplex stainless steel, alloy 20, AL6XN, Hastelloy and GRE. 316 stainless steel is suitable for valves due to the increased material thickness and because the valves are able to be removed for inspection and replacement, as necessary.

(31) The quenching 500, pre-treating 600, washing 320 and washdown 400 nozzles, in the marine exhaust gas scrubber device are metal piping as required to withstand the dry-mode operating temperature of about 265 C. This metallic piping is most preferably super duplex stainless steel (Sandvik SAF2507 or Zenon 100) or similar material suitable for high temperature seawater systems.

(32) Circulation of the fluids is accomplished using pumps and pumping systems known in the art for pumping corrosive and high temperature fluids.

(33) The fluid system includes the following fluid and washdown nozzles, lances and headers: 1) Quencher: 6 nozzles at total 18 gpm at 60 psi, 2) Upper Pre-treatment: 12 nozzles at total 242 gpm at 60 psi 3) Lower Pre-treatment: 12 nozzles at total 242 gpm at 60 psi 4) Washing: single nozzle at 1300 gpm at 60 psi 5) Top washdown: 4 nozzles at total 13 gpm at 25 psi 6) Demisting: 8 nozzles at total 25 gpm at 25 psi 7) Optionally a demister washdown: 1 nozzle at 5 gpm at 60 psi; and 8) Exhaust Outlet washdown: 4 nozzles at total 13 gpm at 25 psi.

(34) The nozzles are 316 stainless steel and are threaded into welded super duplex stainless steel bosses on the lances. The nozzles are removable and replaceable.

(35) Collection Tank

(36) The quenching, pre-treating and washing fluids drain from the marine exhaust gas scrubbing device of the present invention into a fluid circulation tank (not shown). The tank is used to drain all fluid from the device so that there is no standing fluid in the device or local metal supply piping. The tank also collects the fluid and maintains sufficient fluid for pump suction and provides for connections for the treatment fluid injection. Although the capacity of the fluid circulation tank may vary, the tank depicted herein has a total capacity of about 3,000 liters (790 gallons) and a maximum operating capacity of about 2,000 liters (530 gallons) sufficient to collect any water that may drain back into the tank from the fluid circulation piping and marine exhaust gas scrubbing device without possibility of overflowing.

(37) The bottom of the tank slopes to a treatment system drain. The collection tank is fitted with high level switches to ensure that the tank is not overfilled and for control of makeup and fluid water and a magnetic type sight glass for visual level indication. In one option, the tank also has an integral overflow to the bilge waste tank of the vessel to prevent spilling of dirty fluid on the deck in the unlikely event of a tank overflow.

(38) The tank is fabricated from steel with all flanges less than 10 inches in diameter fabricated from super duplex stainless steel. The interior of the tank is coated with a seawater and sodium hydroxide resistant epoxy coating.

(39) The fluid drains from the marine exhaust gas scrubbing device by gravity into a drain header located at least 150 mm below the minimum operation level of the tank to prevent exhaust gas from entering the circulation tank or from crossing over from the pre-treatment to the primary treatment compartments of the device.

(40) The fluid is drawn from the tank by a circulation pump suction header (through the heat exchangers). The maximum operating temperature of the fluid in the circulation tank is limited to 65 C. to ensure that it remains within the operating temperatures of the composite materials of the circulation system piping. In one embodiment, the tank is vented to atmosphere.

(41) Quenching, Pre-Treating and Washing Fluid Properties

(42) The fluid used to scrub the marine exhaust gas is maintained at a desired pH by injection of more concentrated sodium hydroxide from the fluid generator. This includes fluid mixing and storage tank, piping and fluid pump.

(43) In another embodiment, the quenching, pre-treating and washing fluid is a mixture of fresh water and dry concentrated sodium hydroxide pellets or liquid concentrated sodium hydroxide added to the fluid mixing and storage tank. The sodium hydroxide is added to maintain an alkalinity of approximately pH 12 (1000 mmol/l) and has a maximum sodium hydroxide concentration of approximately 10% by weight. The fluid solution at the maximum pH would be equivalent to household drain cleaner and is considered hazardous and corrosive to personnel and equipment.

(44) Seawater Cooling System

(45) The seawater cooling system is required to dissipate the heat transferred from the hot exhaust gas to the quenching, pre-treating and washing-fluid. Preferably, the fluid temperature after cooling is about 35 C. For a 3.25 MW output unit, the required heat capacity of the system is calculated as 3,479 MJ/hour based on the exhaust flow rate and temperature of the current system and accounting for the heat lost through vapourization of the fluid. This has also been confirmed through CFD analysis. The heat rate will vary for other sized units and other types of engines.

(46) The full flow of the fluid system is pumped through a heat exchanger, typically plate type heat exchangers, (in other instances a tube and shell heat exchanger), located on the suction side of the fluid circulation pumps. Several heat exchangers are arranged in parallel in order to meet the required flow rate with standard sized heat exchangers and to allow for one heat exchanger to be taken offline for cleaning while maintaining 66% of the maximum capacity.

(47) Quenching, Pre-Treating and Washing-Fluid Treatment System

(48) The quenching, pre-treating and washing fluid treatment system processes particulate-loaded solution (pH 12, 10 mmol/l or less) collected in the fluid circulation tank to allow for water recirculation in exhaust gas cleaning. The fluid treatment system is triggered by fluid in the circulation tank reaching a 5% or greater solids level. The 5% solids fluid is pumped from the circulation tank to a clarifier where the particulate matter is settled and clean water is overflowed back to the tank for recirculation.

(49) Controlling and Monitoring

(50) The marine exhaust gas scrubbing device is controlled by a main control system. The control system is programmed with redundancy fail safe and an intuitive Human Machine Interface.

(51) For example, the ABB PLC used in the operation of the marine exhaust gas scrubbing device and fluid treatment system is considered to be a major control system component and is certified by DNV for this use. In one embodiment the instrumentation and sensors used to control, monitor and log the system include: Exhaust Gas Analyzer (SOx and CO.sub.2) Fluid Circulation Tank Pressure Fluid Header Flow Fluid Header Temperature Fluid Return Temperature Fluid Header Pressure Fluid Pump Pressure Seawater Pump Pressure Marine exhaust gas scrubber Exhaust Inlet Pressure (outlet is at atmospheric pressure) Marine exhaust gas scrubber Exhaust Inlet Temperature Marine exhaust gas scrubber Exhaust Outlet Temperature Circulation Tank pH Treatment Fluid pH Fluid Level (low, high & high-high) Treatment Fluid Mixing and Storage Tank Level (low & high) Treatment Fluid Spill Tray Leak Detection Fluid Circulation Tank Overflow Detection Marine exhaust gas scrubber Sump Overflow Detection Fluid Circulation Tank Level Sightglass (Magnetic) Treatment Fluid Tank Level Sightglass (Magnetic)

(52) In operation, exhaust gas from a marine engine enters the marine exhaust gas scrubbing device 100 through the exhaust inlet 110. Quencher 500 emits quenching fluid to cool the exhaust gas. The cooled exhaust gas travels through the pre-treater 600 which emits pre-treating fluid to further cool and react with the exhaust gas. The pre-treated exhaust gas travels into the convergent-divergent venturi 300 and through the venturi washer 320 to continue mixing the washing fluid with the exhaust gas. The venturi washdown 310 wets the surfaces of the venturi 300 to dislodge any soot or solid material that forms. The washed exhaust gas travels past the impingement basket 700 further to remove and collect formed solids. The exhaust gas passes through the demister 420 to remove droplets of washing/pre-treating/quenching fluid from the exhaust gas stream. After a final pass through the exhaust washdown 410, the treated and demisted exhaust gas exits the marine exhaust gas scrubbing device via the exhaust outlet 120.

(53) In operation of an alternate embodiment, exhaust gas from a marine engine enters the marine exhaust gas scrubbing device 100 through the exhaust inlet 110. Quencher/pre-treater 550 cools and pre-treats the exhaust gas and butterfly valve 130 induces further mixing of the exhaust gas with the quenching/pre-treating fluid. The pre-treated exhaust gas travels into the convergent-divergent venturi 300 and through the venturi washer 320 to continue mixing the washing fluid with the exhaust gas. The washed exhaust gas travels past sump 250 further to remove and collect formed solids and to collect excess quenching, pre-treating and washing fluid. The exhaust gas passes through the demister 420 to remove droplets of washing/pre-treating/quenching fluid from the exhaust gas stream. The treated and demisted exhaust gas exits the marine exhaust gas scrubbing device via the exhaust outlet 120.

EXAMPLES

Example 1

(54) Three scrubbing performance tests were carried out using the marine exhaust gas scrubbing device of the present invention affixed to a 600 kW diesel engine. In Trial 1, the scrubbing device was run for 108 minutes at 100% engine load with an engine speed of 1750-1800 RPM. During that time the quencher and venturi were in operation with a butterfly valve between the quencher and venturi (to create a turbulent mixing zone) in either a fully open (0), or partially closed (22 or 45) position. In Trial 2, the scrubbing device was run for 35 minutes at 100% engine load with an engine speed of 1800 RPM. After 14 minutes, the butterfly valve was closed to 22 and after 20 minutes the quencher was activated. In Trial 3, the scrubbing device was run for 108 minutes at 100% engine load with an engine speed of 1800 RPM. After 13 minutes the venturi was activated; after 18 minutes the quencher was activated; after 49 minutes the venturi was deactivated; after 58 minutes the butterfly valve was closed to 22; after 62 minutes the butterfly valve was closed to 45; after 101 minutes sodium hydroxide solution was provided to the quencher. SO.sub.x, CO.sub.2 and particulate matter measurements were taken before and after scrubbing of marine engine exhaust.

(55) The device demonstrated on average 99% SO.sub.2 scrubbing of the engine exhaust stream: the SO.sub.2 content in the exhaust gas stream was reduced to 0-10 ppm from 1000 ppm SO.sub.2 gas, which is equivalent to scrubbing the SO.sub.2 produced from burning 1.5% to 3.5% sulfur laden fuel to the 0.1% IMO sulfur regulation limit. In addition, the system consistently captured 80-90% of the PM (particulate matter) by mass.

(56) The table below contains data from the scrubbing performance tests:

(57) TABLE-US-00001 Trial 1 Trial 2 Trial 3 SO.sub.x CO.sub.2 SO.sub.x CO.sub.2 SO.sub.x CO.sub.2 level level PM level level PM level level PM Value ppm ppm level ppm ppm level ppm ppm level Manifold 1100 200 85% 1050 200 85% 975 200 90% QuencherH.sub.2O 1100 200 removal 1050 200 removal 975 200 removal QuencherNaOH 600 200 by mass 625 200 by mass 575 200 by mass Venturi 0 200 0 200 0 200 Sump 0 197 0 192 0 196 Heat Exchanger 0 0 N/A 0 N/A Outlet 0 0 0 192 0 196

Example 2

(58) In another series of tests, the effectiveness of SO.sub.2 reduction as a function of venturi flow was assessed. In a first test (Test B) using a diesel engine operating at full load at an engine speed of 1600 RPM, SO.sub.2 concentration of the exhaust stream was measured at the exhaust manifold and the venturi outlet. Over a period of 17 minutes the venturi flow rate was reduced from 180 gallons per minute (gpm) to 0 gpm (See FIG. 6). In a second test (Test F) using a diesel engine operating at full load, SO.sub.2 concentration of the exhaust stream was measured at the exhaust manifold and the venturi outlet. Over a period of nine minutes the venturi flow rate was reduced from 180 gpm to 0 gpm (See FIG. 6).

(59) One embodiment of the present disclosure resulted in an increase in the scrubbing efficiency of the system. This was accomplished by adding chemical scrubbing capability to the Quencher, the last of the three quencher nozzles concurrently sprays NaOH directly into an adjustable butterfly valve. This creates a turbulent mixing zone prior to the concentric venturi component to further remove any SO.sub.2 from the gas stream not removed via the concentric venturi component.

Example 3

(60) In another test of an embodiment of the marine exhaust gas scrubbing device of the present invention, the device was run at 75% engine load at an engine speed of 1750 rpm. Quenching fluid was emitted from the quenchers at 1.5 gpm at a pressure of 60 psi. The SO.sub.2 level at the device inlet was measured at 1000 ppm and at the device outlet was measured at 0 ppm with a CO level of 301 ppm, a NO level of 633 ppm and a NO.sub.2 level of 2443 ppm.

Example 4

(61) Four additional trials of the marine exhaust gas scrubbing device were carried out. In Trial 1 at an engine speed of 1000 rpm, under an engine load of 15% and with the venturi in operation, the inlet SO.sub.2 level was 1000 ppm and the outlet SO.sub.2 level was 0 ppm, the CO level was 258 ppm, the NO level was 366 ppm and the NO.sub.2 level was 439.2 ppm. In Trial 2 at an engine speed of 1200 rpm, under an engine load of 12% and with the venturi in operation, the inlet SO.sub.2 level was 1000 ppm and the outlet SO.sub.2 level was 0 ppm, the CO level was 619 ppm, the NO level was 273 ppm and the NO.sub.2 level was 327.6 ppm. In Trial 3 at an engine speed of 1400 rpm, under an engine load of 13% and with the venturi in operation, the inlet SO.sub.2 level was 1000 ppm and the outlet SO.sub.2 level was 0 ppm, the CO level was 158 ppm, the NO level was 228 ppm and NO.sub.2 level was 273.6 ppm. In Trial 4 at an engine speed of 1599 rpm, under an engine load of 17% and with the venturi in operation, the inlet SO.sub.2 level was 1000 ppm and the outlet SO.sub.2 level was 0 ppm, the CO level was 148 ppm, the NO level was 211 ppm and the NO.sub.2 level was 253.2 ppm.

(62) As many changes can be made to the preferred embodiment of the invention without departing from the scope thereof, it is intended that all matter contained herein be considered illustrative of the invention and not in a limiting sense.