Systems and methods for delivering dissolved gases into force-main and gravity sewers
View Patent ↗Disclosed are systems and methods for dissolving gases into a fluid that is passing through a force-main and gravity sewer system. The system includes a dissolution tank having a pressure vessel for containing a liquid and for providing a regulated gas head space above the liquid, an inlet that permits passage of wastewater into the gas head space, and an outlet that permits passage of treated wastewater out of the pressure vessel. The system also includes a gas source in communication with the pressure vessel; a pump for supplying wastewater from a force-main or sewer system sump into the pressure vessel under conditions effective to dissolve oxygen gas in the wastewater; and a discharge device in communication with the outlet of the dissolution tank assembly for discharging treated wastewater.
1. A method for pre-treating wastewater in a force-main or sewer system, the method comprising the steps of:
(a) passing an intake fluid into an enclosed vessel;
(b) pressurizing the enclosed vessel with gas, wherein the gas enters the vessel at a controlled pressure and is pressurized until a desired pressure is attained in the vessel;
(c) providing a gas source interfacing with the vessel to regulate the amount and type of gas that enters the vessel;
(d) providing means for removing solids from the intake fluid;
(e) providing means to remove accumulation of solids from the system; and
(f) providing means for introduction of a gasified discharge fluid to be introduced into an enclosed pipe, wherein the means for introduction includes an orifice tube configured to prevent bubble formation within the enclosed pipe.
2. The method of claim 1 , wherein the step of providing a means for removing solids from the intake fluid is provided by an intake screen, in-line grinder, or complete fine screen and de-gritting unit.
3. The method of claim 2 , wherein the intake screen the in-line grinder or the complete fine screen and de-gritting unit provides a means for automatic operation.
4. The method of claim 1 , wherein the step of removing accumulated solids from the system is provided by an operating sequence in which the dissolution vessel is periodically emptied.
5. The method of claim 4 , wherein the operating sequence is controlled by a programmable logic controller or other controller.
6. The method of claim 1 , wherein the step of removing accumulated solids from the system is provided by an actuated valve with an operating sequence which periodically opens the valve to allow purging of the accumulated solids into the sewer.
7. The method of claim 6 , wherein the operating sequence is controlled by a programmable logic controller or other controller.
8. The method of claim 1 , further comprising the step of opening a valve, wherein the valve is of construction which provides a large pressure drop.
9. The method of claim 1 , wherein the orifice tube is inserted through a full-bore ball valve, gate valve, other valve, pipe fitting, pipe saddle, or blind flange with means of insertion of the orifice tube.
10. The method of claim 1 , wherein a quality of the gas in the headspace of the pressurized vessel is monitored for hydrocarbon.
11. The method of claim 10 , wherein the monitoring is performed by a lower-explosive-limit detector or other hydrocarbon detector.
12. The method of claim 11 , wherein a detector is in electronic communication with a programmable logic controller.
13. The method of claim 12 , wherein the programmable logic controller is programmed to sound an audible alarm and/or initiate a system shut-down upon a condition determined by the detector.
14. The method of claim 2 , wherein the condition of the device is monitored by sensing the pressure on a suction line between the device and a pump.
15. The method of claim 14 , wherein the pressure sensing device is a pressure transducer or a pressure switch.
16. The method of claim 14 , wherein the pressure sensing device is in electronic communication with a programmable logic controller.
17. The method of claim 14 , wherein the programmable logic controller is programmed to send an alarm signal and/or initiate a shutdown sequence when the signal from the pressure sensing device indicates a low pressure on the pump intake.
18. The method of claim 1 , wherein the system can be started, stopped, and operated remotely through a distributed control system or a system control and data acquisition (SCADA) system.
19. The method of claim 1 , wherein the discharge of the gasified fluid is recirculated back to a wet-well from which it was drawn.
20. A method for pre-treating wastewater in a force-main or sewer system, the method comprising the steps of:
(a) passing an intake fluid into an enclosed vessel;
(b) pressurizing the enclosed vessel with gas, wherein the gas enters the vessel at a controlled pressure and is pressurized until a desired pressure is attained in the vessel;
(c) providing a gas source interfacing with the vessel to regulate the amount and type of gas that enters the vessel, wherein a quality of the gas in a headspace of the vessel is monitored for hydrocarbon;
(d) providing means for removing solids from the intake fluid;
(e) providing means to remove accumulation of solids from the system; and
(f) providing means for introduction of a gasified discharge fluid to be introduced into an enclosed pipe.
21. A method for pre-treating wastewater in a force-main or sewer system, the method comprising the steps of:
(a) passing an intake fluid from a sump or a wet-well into an enclosed vessel;
(b) pressurizing the enclosed vessel with gas, wherein the gas enters the vessel at a controlled pressure and is pressurized until a desired pressure is attained in the vessel;
(c) providing a gas source interfacing with the vessel to regulate the amount and type of gas that enters the vessel;
(d) providing means for removing solids from the intake fluid; and
(e) passing a gasified discharge fluid from said enclosed vessel to said sump or said wet-well.