US2760342A - Means for diluting combustible gas and the like - Google Patents

Description

Aug. 28, 1956 w. L. MORRISON 2,760,342

MEANS FOR .DILUTING COMBUSTIBLE GAS AND THE LIKE Filed Aug. 20, 1954 3 Sheets-Sheet 1 Aug. 28. 1956 w. L. MORRISON 2,760,342

MEANS FOR DILUTING COMBUSTIBLE GAS AND THE LIKE Filed Aug. 20, 1954 2 Sheets-Sheet 2 by Parker 8. Carter ATTORNEYS United States Patent NIEANS FOR DILUTING COMBUSTIBLE GAS AND THE LIKE Willard L. Morrison, Lake Forest, 111., assi nor, by mesne assignments, to Constock Liquid Methane @Corporation, New York, N. Y., a corporation of Delaware Application August 20, 1954, Serial No. 451,272

8 Claims. (Cl. 62*1) My invention relates to the method and apparatus for safely wasting gases to atmosphere.

One object of my invention is to provide a method and apparatus for safely wasting the combustible gas evaporated from such a cold boiling liquid as liquefied methane when such a liquid is stored at approximately atmospheric pressure.

Circumstances can occur when the rate of evaporation resulting from ambient heat will be greater than the gas demand. Under these conditions, it is essential that, in order to maintain the pressure in the storage tank below a safe limit adjacent atmospheric, the gas be safely wasted.

The tank and system will be designed to hold the liquid and to maintain a pressure slightly above atmospheric, such that the evaporated gas will fiow out as desired; for example, five pounds gauge. Any pressure above that is dangerous, and to prevent development of excessive pressure the gas must be released by discharge to atmosphere.

Since the gas is combustible and, when mixed with the right amount of air, will produce an explosive mixture,

it is essential that the excess gas as discharged from the tank be diluted with a suitable solvent in such proportions that a dilute incornbustible mixture results for discharge to atmosphere.

I propose to provide the volume of air necessary to dilute the gas to a safely lean mixture, by using the excess gas as it is discharged from the tank as a motive fluid in an expansion engine to compress or impel ambient air for mixing with the gas exhausted from the turbine.

Other objects will appear from time to time throughout the specification and claims.

My invention is illustrated more or less diagrammatically in the accompanying drawings, wherein:

Figure l is a plan view of a vessel and storage tank to which my invention is applied;

Figure 2 is a diagrammatic layout of a modified form of the discharge and dilution means when applied to a tank on shore;

Figure 3 is a diagrammatic layout of a further modified form of my invention;

Figure 4 is a diagrammatic layout of a further modified form.

Like parts are indicated by like characters throughout the specification and drawings.

1 is a water-borne vessel, 2 an insulated tank carried thereby adapted to contain at approximately atmospheric pressure a mass of cold boiling liquid, for example, methane or other liquefied petroleum gas. 3 is an engine, preferably an internal combustion engine, adapted to propel the boat. 4 is a gas supply pipe leading from the tank 2 to the engine 3. '5 is a valve for control of gas flow to the engine. 6 is a pressure relief pipe leading from the tank 2 to a pressure relief valve 7. 8 is a gas discharge pipe leading from the pressure relief valve to a turbine 9. 16 is a turbine exhaust pipe leading to the mixing nozzle 11. The turbine 9 drives a compressor 12 which draws in air and discharges it through the air duct 13 to the mixing nozzle 11 so that the pressure of the gas discharged through the pressure relief valve actuates a turbine to compress air and discharge it for mixing with the exhaust gas from the turbine in the pressure nozzle with the waste gas.

Figure 2 illustrates my invention applied to a tank 12 on shore; 1'3 is a gas supply pipe controlled by valve 14 for usual discharge of the gas to point of use. The pipe 6, pop valve 7, pipe 3, turbine 9, and compressor 12 are just as in Figure l, but turbine exhaust pipe 15 and compressor exhaust pipe 16 join before they discharge into mixing nozzle 1-7.

In the modified form of Figure 3, the pop valve 18 carries an actuating arm .19 which, as the pressure increases and the valve is just about to open, contacts the pad 26 on switch arm 21 to close contact 22 to close an electrical circuit from a suitable source of power at 23 through conductor 24, contact 22, conductor 25, solenoid 26, conductor 27, back to power source 23.

Solenoid 26 opens valve 28 to release a shot of high pressure gas, preferably CO2, from pressure bottle 29 through pipe 3:) and pipe 31 to turbine 19. This shot of high pressure gas starts the turbine spinning so that when the gas from tank 2 or 12 reaches the turbine the inertia of turbine compressor combination will have been overcome and no delay in the discharge of air for mixture with the gas exhausted from the turbine will occur.

As the valve 18 and arm 19 complete their movement to open position, switch .21 will open so gas from tank 29 will not be wasted. The same effect will occur as the valve closes so the CO2 will in another shot mix with the as and insure purging of the system after the gas pressure is shut off.

In the modified form of Figure 4, as the valve 18 opens, arm 19 will close switch 39 and hold it closed as long as valve 18 is open; this closes a circuit from power source 31 through conductor 32, switch 30, conductor '33, electric motor $4, conductor 35, to power source 31 so motor 34 will assist gas pressure in turbine 9 to compress or discharge air for mixing with the gas.

The details of the turbine, compressor, nozzle and relief valve are not here illustrated since they are conventional and their details form no part of the present invention.

For example, if a normal desired pressure in the tank is two pounds gauge and five pounds is safe, the relief valve will be set to blow off at five pounds, but it will also be set to remain wide open until the pressure drops to two pounds. Thus, between two and five pounds gauge, the valve will be wide open and the turbine will receive the full discharge of relief gas. When the turbine operates the compressor, the exhaust gas discharged to the mixing nozzle will be discharged at the exhaust pressure of the turbine, preferably atmospheric, and will there be mixed with an adequate supply of air to insure an air-gas mixture so lean as not to support combustion.

The relief valves 7 and .18 are the usual type of pop valves which open when the discharge pressure is reached and remain open until a desired pressure drop occurs and then close at a pressure substantially below the opening pressure.

The velocity of the combined gas and air column discharged from the mixing nozzle will preferably be greater than the rate of flame propagation in a combustible methane gas mixture at atmospheric pressure.

The usual safeguards in the gas pipe itself to prevent flame propagation will be provided; for example, a screen embodying the Davey miners lamp principle.

Iclaim:

1. A safety device for discharge of combustible gas under pressure from storage to atmosphere including a discharge passage, a pressure relief valve therefor adapted to open when a predetermined maximum, and to remain open until a predetermined minimum pressure has been reached, an expansion engine adapted to be driven by the gas discharged through the valve, a blower driven by the expansion engine adapted'to discharge a column of air, means for mixing the air with the gas discharged from the expansion engine and discharging the mixture to atmosphere, means separate and apart from the discharged gas for commencing blower operation immediately before admission of discharged gas to the expansion engine and for continuing blower operation for a short period after the gas is discharged to the said expansion engine.

2. A safety device for discharge of combustible gas under pressure from storage to atmosphere including a discharge passage, a pressure relief valve therefor adapted to open when a predetermined maximum, and to remain open until a predetermined minimum pressure has been reached, an expansion engine adapted to be driven by the gas discharged through the valve, a blower driven by the expansion engine adapted to discharge a column of air, means for mixing the air with the gas discharged from the expansion engine and discharging the mixture to atmosphere, means separate and apart from the discharged gas for commencing blower operation immediately before the valve opens.

3. A safety device for discharge of combustible gas under pressure from storage to atmosphere including a discharge passage, a pressure relief valve therefor adapted to open when a predetermined maximum, and to remain open until a predetermined minimum pressure has been reached, an expansion engine adapted to be driven by the gas discharged through the valve, a blower driven by the expansion engine adapted to discharge a column of air, means for mixing the air with the gas discharged from the expansion engine and discharging the mixture to atmosphere, said means including a carbon dioxide gas bottle, a control valve therefor, a connection between it and the engine, means associated with the relief valve responsive to the pressure of the combustible gas for opening the control valve for a suflicient length of time before the relief valve opens to discharge a shot of carbon dioxide under pressure into the engine to start its operation.

4. A safety device for discharge of combustible gas under pressure from storage to atmosphere including a discharge passage, a pressure relief valve therefor adapted to open when a predetermined maximum, and to remain open until a predetermined minimum pressure has been reached, an expansion engine adapted to be driven by the gas discharged through the valve, a blower driven by the expansion engine adapted to discharge a column of air, means for mixing the air with the gas discharged from the expansion engine and discharging the mixture to atmosphere, supplemental motor means adapted to drive the blower, means associated with the relief valve responsive to the pressure of the combustible gas for actuating the supplemental motor during the time that the pressure relief valve is open.

5. Means for the safe discharge of a combustible gas under pressure from a container into the atmosphere including a discharge passage in communication with the container and having a discharge opening through which the combustible gas is exhausted into the atmosphere,

means operative in response to the movement of gas through the discharge passage for displacement of air from the atmosphere into the discharge passage, means for admixture of the air with the gas in the discharge passage prior to exhaust into the atmosphere, and means separate and apart from the discharged gas for operation of the air displacement means responsive to the release of gas from the container into the discharge passage for operation thereof prior to exhaust of the gas into the atmosphere whereby the air becomes admixed therewith prior to the exhaust of the gas into the atmosphere.

6. Means for the safe discharge of a combustible gas under pressure from a container into the atmosphere comprising a discharge passage, a pressure relief valve adapted to open when a predetermined maximum and to remain open until a predetermined minimum pressure has been reached in the container, means operative in response to the movement of gas through the discharge passage for displacement of air from the atmosphere into the discharge passage, means for mixing the air with the gas prior to exhaust from the discharge passage, and other means responsive to the opening of said relief valve for operation of the said an displacement means for causing displacement of air into the discharge passage in advance of the passage of gas therethrough for admixture therewith prior to exhaust of the gas into the atmosphere.

7. Means for the safe discharge of a combustible gas under pressure from a container into the atmosphere comprising a discharge passage, a pressure relief valve adapted to open when a predetermined maximum and to remain open until a predetermined minimum pressure has been reached in the container, means operative in response to the movement of gas through the discharge passage for displacement of air from the atmosphere into the discharge passage, means for mixing the air with the gas prior to exhaust from the discharge passage, and other means responsive to the opening and closing of the relief valve for efiecting operation of the said air displacement means to cause displacement of air prior to and after the exhaust of gas through the discharge opening.

8. Means for the safe discharge of a combustible gas under pressure from a container into the atmosphere comprising a discharge passage, a blower operative in response to the movement of gas through the discharge passage for displacement of air from the atmosphere into the discharge passage, means for mixing the air with the gas in the discharge passage for exhausting the mixture to the atmosphere, and means responsive to the exhaust of gas from the container into the discharge passage for commencing operation of the blower in advance of passage of the gas into the atmosphere for admixture of air with the gas prior to its exhaust into the atmosphere.

References Qited in the file of this patent UNITED STATES PATENTS 262,185 Johnson et al Aug. 1, 1-882 1,583,621 Steinberg May 4, 1926 2,332,227 Jackson Oct. 19, 1943 2,507,380 Morrison May 9, 1950 2,543,653 Woog Feb. 27, 1951 2,552,472 Whidden May 8, 1951

Images