Ozone generating machine with electrical closed cabinet cooled by closed loop

Abstract

Ozone generating machine (OGM) for generating ozone in a ship, comprising: an ozone generator with at least two electrodes separated by an ozonizing gap and at least a gas inlet for receiving a feed gas containing dioxygen, and a gas outlet for exhausting gas comprising ozone to an ozone circuit of the ship, a main liquid cooling circuit (CWP, CWT), with at least a cooling portion in the ozone generator, to be connected with a cooling circuit of a ship, a liquid-liquid heat exchanger (LLHEX) connected with the main liquid cooling circuit (CWP, CWT), and an electrical closed cabinet (ECB) comprising an electric current converter (ECV),
characterized in that the ozone generating machine (OGM) further comprises a closed loop cooling liquid circuit (CLC) comprising a converter liquid cooling portion (CECV) arranged to cool the electric current converter (ECV) and connected with the liquid-liquid heat exchanger (LLHEX).

Claims

1. An ozone generating machine (OGM) for generating ozone in a ship, comprising: an ozone generator (OG) with at least two electrodes (E1, E2) separated by an ozonizing gap (OZ) and a dielectric layer, the ozone generator (OG) comprising at least a gas inlet (O21N) for receiving a feed gas containing dioxygen, and a gas outlet (O3OUT) for exhausting gas comprising the generated ozone to an ozone circuit of the ship to supply the generated ozone to ballasts of water of the ship, a main liquid cooling circuit (CWP, CWT), at least one portion of the main liquid cooling circuit (CWP, CWT) being located inside the ozone generator (OG), to be connected with a cooling circuit of the ship, a liquid-liquid heat exchanger (LLHEX) connected with the main liquid cooling circuit (CWP, CWT), and an electrical closed cabinet (ECB) comprising an electric current converter (ECV), characterized in that the ozone generating machine (OGM) further comprises a closed loop cooling liquid circuit (CLC) connected with the liquid-liquid heat exchanger (LLHEX) and comprising a converter liquid cooling portion (CECV) arranged to cool the electric current converter (ECV).

2. The ozone generating machine (OGM) according to claim 1, wherein the liquid-liquid heat exchanger (LLHEX) comprises at least two internal circuits, one internal circuit being connected to the main liquid cooling circuit (CWP, CWT), and one other internal circuit being connected to the closed loop cooling liquid circuit (CLC).

3. The ozone generating machine (OGM) according to claim 1, wherein the closed loop cooling liquid circuit (CLC) has a total volume no greater than three liters.

4. The ozone generating machine (OGM) according to claim 1: wherein a lowest electrical device of the electrical closed cabinet (ECB) is installed at a predetermined distance from an internal lowest surface of the electrical closed cabinet (ECB), thereby defining an electrical closed cabinet bottom volume where there is no electrical device, and wherein the closed loop cooling liquid circuit (CLC) has a total volume no greater than said electrical closed cabinet bottom volume, in order to avoid a contact between lower electrical device and closed loop cooling liquid in case of liquid leakage of said closed loop cooling liquid circuit (CLC).

5. The ozone generating machine (OGM) according to claim 4, wherein the electrical closed cabinet (ECB) further comprises an air-liquid heat exchanger (ALHEX) connected with the closed loop cooling liquid circuit (CLC) and arranged to cool air inside the electrical closed cabinet (ECB).

6. The ozone generating machine (OGM) according to claim 5, wherein the air-liquid heat exchanger (ALHEX) comprises an internal circuit connected to the closed loop cooling liquid circuit (CLC).

7. The ozone generating machine (OGM) according to claim 5 wherein the electrical closed cabinet (ECB) further comprises an electric current transformer and a transformer fan (FN) arranged to blow air onto said electric current transformer, after sucking it from the said air-liquid heat exchanger (ALHEX).

8. The ozone generating machine (OGM) according to claim 5 further comprising a heat exchanger fan (FN) arranged to suck air from said air-liquid heat exchanger (ALHEX).

9. The ozone generating machine (OGM) according to claim 5 further comprising a cabinet fan (FN) arranged to create an air circulation inside said electrical closed cabinet (ECB).

10. The ozone generating machine (OGM) according to claim 1, further comprising at least one air temperature sensor (ATS) arranged to measure air temperature inside said electrical closed cabinet (ECB).

11. The ozone generating machine (OGM) according to claim 1, further comprising at least one liquid temperature sensor (LTS) arranged to measure liquid temperature inside the closed loop cooling liquid circuit (CLC).

12. The ozone generating machine (OGM) according to claim 1, further comprising: at least one liquid temperature sensor (LTS) arranged to measure a liquid temperature inside the closed loop cooling liquid circuit (CLC) and arranged upstream the electric current converter (ECV), at least one flow switch arranged to detect liquid flow inside the closed loop cooling liquid circuit (CLC), in order to monitor that said electric current converter (ECV) is cooled.

13. The ozone generating machine (OGM) according to claim 1, further comprising at least one liquid pressure sensor arranged to measure liquid pressure inside the closed loop cooling liquid circuit (CLC).

14. The ozone generating machine (OGM) according to claim 1, further comprising a liquid circulation pump (CRP) connected to the closed loop cooling liquid circuit (CLC).

15. Ship (S) comprising an ozone generating machine (OGM) according to any one of the preceding claims.

Description

(1) Other features and advantages of the present invention will appear more clearly from the following detailed description of particular non-limitative examples of the invention, illustrated by the appended drawings where:

(2) FIG. 1 represents a schematic diagram of a part of the ozone generating machine comprising an electric closed cabinet according to the invention;

(3) FIG. 2 represents a perspective view of the ozone generating machine according to the present invention;

(4) FIG. 3 represents a simplified cross section of the ozone generator according to the present invention;

(5) FIG. 4 represents a schematic diagram of the ozone generating machine according to the present invention;

(6) FIG. 5 represents a ship equipped with an ozone generating machine according to the invention.

(7) The ozone generating machine OGM machine shown on FIGS. 1, 2 and 3 mainly comprises an ozone generator OG, an electrical closed cabinet ECB, which can be done also in two separated or half cabinets C1 and C2, and a frame F for supporting the ozone generator OG and the electrical closed cabinet ECB. Of course, such machine comprises also numerous valves, sensors, pipes, electric devices to ensure automatic generation of ozone. In particular, the depicted machine is designed for use in ships or vessels, having a need to sanitize ballasts water, to avoid cross-harbor water contamination for example. FIG. 5 represents a ship S comprising ballasts BA (full of water) and an ozone generating machine OGM, connected to an ozone circuit O3C of the ship S, to supply ozone to the ballasts BA. Indeed, water contained in the ballasts BA need to be treated/sanitized before being released, and ozone is supplied by the ozone circuit O3C directly into the ballasts BA, where ozone bubbles are visible.

(8) The ozone generator OG comprises a plurality of electrodes sets ES placed within a housing H, as shown on FIG. 3. Each electrodes set comprises two electrodes E1 and E2, separated by an ozonizing gap OZ, and a dielectric layer (not shown on figures for clarity). The ozone generating machine OGM comprises also an electric power unit EPU shown FIG. 4 for supplying electric current to each of the electrodes sets ES. Each ozonizing gap OZ is connected upstream to a gas inlet O2IN of the ozone generator OG for receiving a gas containing dioxygen, and downstream to a gas outlet O3OUT for exhausting gas containing ozone, when the ozone generating machine OGM is operated.

(9) In an embodiment, the electrodes are metallic, and the dielectric layer comprises a ceramic coating, applied onto at least one of the electrodes.

(10) The gas containing dioxygen might be supplied by the ship network, a bottle, or might be air. When electric power is supplied to the electrodes and gas flow is established, electric discharges occur in the ozonizing gap OZ between the electrodes E1 and E2 allowing corona affect, and a portion of oxygen supplied at the gas inlet O2IN is transformed into ozone, which is exhausted at the gas outlet O3OUT in a given amount.

(11) To ensure stable conditions during production of ozone, a liquid cooling circuit comprises a cooling path within the ozone generator OG, so that a cooling liquid can flow through the ozone generator OG, to cool directly each of the electrodes sets ES. FIG. 3 shows that cooling water WC is present in the housing H of ozone generator OG. The ozone generator OG comprises an inlet of water cooling WCIN, and an outlet of water cooling WCOUT as shown in FIG. 4. As shown in FIG. 1, the ozone generating machine OGM further comprises a main liquid cooling circuit CWP. CWT, and at least one portion of the main liquid cooling circuit CWP, CWT being located inside the ozone generator OG, to be connected with a cooling circuit of the ship, and further comprises a liquid-liquid heat exchanger LLHEX connected with the main liquid cooling circuit CWP, CWT. Further, the main liquid cooling circuit CWP, CWT comprises an upstream portion CWP, located upstream the liquid-liquid heat exchanger LLHEX and a downstream portion located downstream the liquid-liquid heat exchanger LLHEX. The liquid-liquid heat exchanger LLHEX is located outside and narrow the electrical closed cabinet ECB. The at least one portion of main liquid cooling circuit CWP, CWT being located inside the ozone generating machine OGM is thereby connected to the inlet of water cooling WCIN, and to the outlet of water cooling WCOUT, as being part of the main liquid cooling circuit CWP, CWT, considering FIGS. 1 and 4 together.

(12) As shown in FIG. 1, the electrical closed cabinet ECB comprises an electric current converter ECV distributing current to the electrodes sets ES of the ozone generator OG. To provide an efficient cooling of the electric current converter ECV, the ozone generating machine OGM further comprises a closed loop cooling circuit liquid CLC connected with the liquid-liquid heat exchanger LLHEX and comprising a converter liquid cooling portion CECV arranged to cool the electric current converter ECV. The ozone generating machine OGM further comprises a liquid circulation pump CRP connected to the closed loop cooling liquid circuit CLC, allowing circulation of the liquid inside the closed loop cooling liquid circuit CLC. Said cooling liquid is preferably water or water with additives, but could be any other calorific transport fluid.

(13) The liquid-liquid heat exchanger LLHEX comprises at least two internal circuits, one internal circuit being connected to the main liquid cooling circuit CWP, CWT, and one other internal circuit being connected to the closed loop cooling liquid circuit CLC. The closed loop cooling liquid circuit CLC is thereby partly arranged inside the closed electrical cabinet ECB. As the electrical closed cabinet ECB is closed to avoid any dust or the like to enter inside, and create pollution, the electrical components or devices of the electrical closed cabinet ECB should be cooled, as there is no natural fresh air convection as for open electrical cabinet. The main electrical component is the electric current converter ECV that is cooled by the converter liquid portion CECV. Other electrical components such as electric current transformer are cooled thanks to a transformer fan FN arranged to blow air onto said electric current transformer after sucking air from an air-liquid heat exchanger ALHEX of the electric closed cabinet ECB. The air-liquid heat exchanger ALHEX comprises an internal circuit connected to the closed loop cooling liquid circuit CLC. The transformer fan FN can also blow air to create air circulation inside electrical closed cabinet ECB.

(14) A set of sensors is provided with the electrical closed cabinet ECB, such as an air temperature sensor ATS arranged to measure air temperature inside said electrical closed cabinet ECB, a liquid temperature sensor LTS arranged to measure liquid temperature inside the closed loop cooling liquid circuit CLC, a flow switch or a flow sensor LFS arranged to detect or to measure the flow of liquid inside the closed loop cooling liquid circuit CLC. The set of sensors can thereby provide information about the health of the electrical closed cabinet ECB and allow to change parameters to better cool the electrical closed cabinet ECB, such as for example adjust the flow and/or the temperature of liquid in the closed loop cooling liquid circuit CLC, change the speed of the transformer fan FN, or any other adjustment or retroacting correction to allow temperature management of the electrical closed cabinet ECB.

(15) In addition, the dot line on the closed loop cooling liquid circuit CLC is representing an example of the arrangement of the same. The closed loop cooling liquid circuit CLC presents a limited volume, for example three liters or the like, small compared to the main liquid cooling circuit CWP, CWT. This allows to have a small amount of liquid in case of leakage or failure inside the electrical closed cabinet ECB. The electrical components of devices inside the electrical closed cabinet ECB are located at a predetermined distance such as ten cm or fifty cm or the like, thereby defining an electrical closed cabinet bottom volume in order to avoid any contact between liquid and electric component. The same is done for electric current converter ECV or electric current transformer. The closed loop cooling liquid circuit CLC is equipped with a low point valve or drain valve and other necessary connecting point, and the electrical closed cabinet ECB is equipped with a low point check valve allowing a liquid leakage to be evacuated but keeping the electrical closed cabinet ECB airtight.

(16) Also for safety, sensors of the electric current converter ECV are equipped with a switch off function in order to switch off the electric current converter ECV if needed. Safety management and switch off order are managed through a programmable logic controller usually know as PLC.

(17) In other hand, the ozone generating machine OGM can typically be operated in the following ranges:

(18) range of power density: [0.1 to 10] kW per square meter of electrode

(19) range of electric current frequency: [10 to 30000] Hz

(20) upper limit of peak voltage: [2-20] kV

(21) Ozone concentration at the gas outlet: 1-16% by weight

(22) Range of absolute pressure of feed gas, [0.5 bar(a)-6.0 bar(a)]

(23) It might be desired that Nitrogen (N2) and/or Argon (Ar) is present in the feed gas at least with a concentration of: 0.1-5% by weight, and the rest is dioxygen. Alternatively, one can supply air to the ozone generator OG.

(24) The ozone generating machine OGM is also equipped with adequate sensors to monitor and check the ozone production, and the machine can comprise, as shown on FIG. 4 an oxygen concentration sensor OCS, an oxygen pressure sensor OPS, an oxygen flow sensor OFS, an ozone concentration sensor O3S, an ozone pressure sensor O3PS, an ozone circulation flow sensor O3Q, an inlet water cooling temperature sensor IWCTS and an outlet water cooling temperature sensor OWCTS, an inlet water cooling flow sensor IWCQS and an outlet water cooling flow sensor OWCQS, electrode power measurement means EPS with for example an electrode intensity sensor, an electrode voltage sensor, and a frequency sensor. These sensors are equipped with a deported display located inside the electrical closed cabinet ECB.

(25) The frame F supports the ozone generator OG via a top subframe TSF, lies onto the ground via a base B and comprises pillars P between the top subframe TSF and base B. The base B is also supporting the electrical closed cabinet ECB. Same conception with pillars P and top subframe TSF can be used for supporting the electrical closed cabinet ECB upon need.

(26) Typically the base B and top subframe TSF are metallic structures comprising welded beams and plates: to ensure adequate resting surfaces or platen areas, for attachment of the components of the ozone generating machine. Welding technique is an example of assembly, but the beams and plates might be attached together with nuts/bolts/screws, to allow easy dismantling/transportation/installation of the frame F. Indeed, as the ozone generating machine OGM is designed to be installed into a ship, one shall take into account the installation in a reduced space, with limited access. This leads to choose between welding assembly for parts having small dimensions/footprint and nuts assembly for parts having larger dimensions/footprint.

(27) Pillars P are supporting the top subframe TSF and are attached to the base B.

(28) As shown FIG. 2, the ozone generator OG is typically located at breast height (between 1 m and 1.6 m from ground), for maintenance reasons: to provide an easy access for the electrodes E1, E2 located within the ozone generator OG, as shown FIG. 3. This is also the case for upper half cabinet C1.

(29) The weight and dimensions of the ozone generator OG are significant (Ø of about [300-800] mm and [800-3000] mm length, weight from 50 kg to 1500 kg), added to the weight of other organs of the ozone generating machine OGM (electric cabinets C1. C2: pipes, valves . . . ) results in stress, strain and displacements when the machine is subjected to vibrations, commonly present in a marine application.

(30) As an example, it might be required that the electrical closed cabinet ECB or any component of the OGM has to fulfil a vibration range of 2 to 100 Hz vibration, and at the resonance frequency it is not allowed to have (as described in the D. N. V standard for certification No. 2.4 “Environmental test specification for instrumentation and automation equipment,”. April 2006): more than 1 mm displacement between 2 and 13.2 Hz and more than 6860 mm/s.sup.2 acceleration between 13.2 and 100 Hz, comparing the base frame to other parts especially on top of the ozone generating machine OGM.

(31) In order to minimize the acceleration and/or displacements when subjected to vibrations, the frame F is designed in the specific following way. Cross-brace beams are positioned in the longitudinal direction of the machine, to link pairs of pillars P located under the ozone generator OG. Consequently, the pillars P linked together by the cross-brace beams are firmly held together.

(32) In addition, the frame F comprises reinforcing plates, and in particular top reinforcing plates attached via two bolts to the top portion of the pillars P and via two bolts to the top subframe TSF, thereby increasing the rigidity of the joint. Similarly, bottom reinforcing plates are attached via two bolts to the bottom portion of the pillars P and via two bolts to the base B, thereby increasing the rigidity of the joint.

(33) The cross-brace beams are also attached via two bolts to the reinforcing plates, to provide a simple and robust structure.

(34) In addition, dampers D are positioned between the ground and the base B to minimize the transmission of vibrations to the frame F. At least four dampers D are placed directly below the ozone generator OG, but as shown FIG. 2, ten dampers total are attached to the bottom face of the base B. Some of these dampers are directly attached to the ground, to prevent any relative movement between the ground and the ozone generating machine OGM (slippage, falling over . . . ).

(35) The dampers D are chosen to have a low vertical size (less than 100 mm), and to resist to the weight of the machine. Typically, such dampers D are comprising a rubber arranged between a first attachment portion attached to the frame F, and a second attachment portion, attached to or laying onto the ground.

(36) At least four dampers D are positioned vertically below the ozone generator OG, and intermediate dampers ID are placed between the ozone generator OG and the top subframe TSF, to minimize as much as possible the vibrations of the heaviest part (the ozone generator OG) of the ozone generating machine OGM.

(37) In addition, one should note that the cross-brace beams are positioned parallel to the longitudinal dimension of the ozone generating machine OGM, defined by the axial direction of the ozone generator OG. Therefore organs or devices might be placed between the two pairs of cross-brace beams, and the machine comprises at least one door, for closing an opening in the frame F through which the organs or devices placed between the two pairs of cross-brace beams can be removed or inserted, for maintenance reasons. In particular, it is advantageous to position and attach in the bottom portion of the ozone generating machine OGM heavy electric devices such as current transformers or converters, to increase stability. The transverse door and its opening, arranged large enough to allow passage of these devices, avoids the need to remove the cross-brace beams.

(38) It is of course understood that obvious improvements and/or modifications for one skilled in the art may be implemented, still being under the scope of the invention as it is defined by the appended claims.