LNG VAPORIZATION

Abstract

Apparatus and methods for vaporizing LNG while producing sufficient volume of compressed natural gas at sufficient pressure to meet the needs of internal combustion engines, gas turbines, or other high consumption devices operating on natural gas or on a mixture of diesel and natural gas. The LNG vaporizer of the present invention incorporates a reciprocating pump to provide vaporized LNG to an output at rates and pressures as required by the particular application. The heat rejected into the engine coolant and the exhaust stream from an artificially loaded internal combustion engine, as well as the hydraulic heat resulting from artificially loading the engine, is transferred to the LNG as the LNG passes through a heat exchanger. Exhaust heat is transferred to the engine coolant after the coolant passes through the heat exchanger.

Claims

1. (canceled)

2. (canceled)

3. (canceled)

4. (canceled)

5. (canceled)

6. A method of vaporizing LNG from an LNG source utilizing an internal combustion engine and circulating engine coolant, the engine being loaded by driving a hydraulic pump that pumps hydraulic fluid through a restricted orifice, comprising the steps of: driving the hydraulic pump with the internal combustion engine, the hydraulic fluid being pumped through the restricted orifice to load the engine, thus heating the hydraulic fluid, engine coolant, and engine exhaust; routing LNG from the LNG source to a reciprocating pump; transferring heat from the heated hydraulic fluid and the heated engine coolant to LNG output from the reciprocating pump; and transferring heat from the heated engine exhaust to the engine coolant.

7. The method of claim 6 wherein heat is transferred from the heated engine exhaust to the engine coolant after heat is transferred from the heated engine coolant to the LNG.

8. The method of claim 6 additionally comprising combining any vapor lost from the LNG source with the output from the reciprocating pump.

9. The method of claim 6 wherein LNG output from the reciprocating pump is output at a pressure ranging from about 400 to about 10,000 psi.

10. The method of claim 6 wherein sufficient heat is transferred from the heated engine exhaust that the engine coolant can be returned to the internal combustion engine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a schematic, or layout, diagram of a system incorporating an LNG vaporizer constructed in accordance with the teachings of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0016] Referring to FIG. 1, LNG is provided to a storage tank 10 by one or more LNG transport trucks 12 through a loading manifold 14, all constructed in accordance with known LNG storage and handling systems. LNG is output from storage tank 10 through supply line 16 to the LNG vaporizer of the present invention, indicated generally at reference numeral 18, that is itself powered by an internal combustion engine 19 that may be diesel or natural gas powered, or that may be powered on a mix of diesel and natural gas. The internal combustion engine 19 of LNG vaporizer 18 is artificially loaded by driving a hydraulic pump 20 that pumps hydraulic fluid through the restricted orifice 22 of a sequencing valve, the engine 19 producing more heat that is captured in the engine coolant as engine 19 works harder and burn more fuel to push hydraulic fluid through valve orifice 22. In the embodiment described herein, the internal combustion engine 19 of LNG vaporizer 18 provides three heat sources, the hydraulic fluid, the engine exhaust, and the high temperature engine coolant, and all three heat sources are used to advantage in the method and apparatus described below.

[0017] The engine 19 of LNG vaporizer 18 also powers a hydraulically-driven booster pump 24 provided for the purpose of feeding LNG through line 26 to the suction side of a hydraulically-driven reciprocating pump 28, which may be a simplex, duplex, triplex, or other multiple-cylinder pump. Those skilled in the art who have the benefit of this disclosure will recognize that the booster pump 24 is not always utilized, and may not even be needed, in installations in which the LNG source, such as LNG tank 10 or transports 12, provides LNG at sufficient pressure to the suction side of reciprocating pump 28. For instance, some LNG tanks provide LNG at sufficient pressure that a booster pump is not needed and some LNG tanks are provided with internal pumps that provide LNG at the pressure needed at the suction side of reciprocating pump 28. Reciprocating pump 28 builds sufficient pressure in the input line 30 to heat exchanger 32 to overcome the 200-1000 psi pressure drop characteristic of passage through a heat exchanger with the result that the natural gas output through line 34 to the compressed natural gas (CNG) tank 36 or other equipment (see the description of valve 37 and line 39, below) can be in the 400-10,000 psi range, more particularly, 500-2500 psi, to overcome further pressure drop or resistance downstream depending upon the needs of the particular installation or application. As illustrated in FIG. 1, the output line 38 from CNG tank 36 is connected to an industrial plant, electric power plant, temporary pipeline, a well head for applications in which the vaporized natural gas is utilized at volumes and pressures sufficient for well servicing and/or well completion operations (for instance, at pressures high enough to break the rupture disks used to isolate one zone from another), the internal combustion engines of a drilling rig or frac fleet, or any of the many other applications and/or installations in which natural gas is used to advantage. As also shown in FIG. 1, output line 36 is provided with a by-pass or diverter valve 37 and line 39 for routing the vaporized natural gas directly to the industrial plant, electric power plant, or any of the many other applications and/or installations in which large volumes of pressurized natural gas are used to advantage.

[0018] As noted above, the internal combustion engine 19 of LNG vaporizer 18 outputs three heat sources, and heat exchanger 32 receives inputs from two of those sources, the engine coolant at temperatures typically ranging between about 170-190 degrees F. and the hydraulic fluid used to load engine 19 at temperatures typically ranging between about 160-200 degrees F. The third heat source, namely the engine exhaust, enters a second heat exchanger 40 with the engine coolant in the line 42 at temperatures ranging between about 110-170 degrees F. as the coolant is returned to engine 19 from heat exchanger 32. The LNG flow passing in line 30 through heat exchanger 32 strips enough heat from the engine coolant in heat exchanger 32 that engine coolant is returned to the engine through second heat exchanger 40 so that coolant heated by the engine exhaust in second heat exchanger 40 is heated to the coolant temperature specified for the particular engine 19 (typically in the 160-180 degree F. range).

[0019] No matter how well the LNG storage tank 10 and/or transports 12 is/are insulated, some vapor is lost from tank 10/transports 12 which is typically vented to the atmosphere. The present invention provides a means to collect the vapor from the LNG storage tank 10 and LNG transport 12 and direct that collected vapor to vapor supply line 44, thus preventing the vapor/gas from being vented to the atmosphere and preserving the natural gas for meaningful use. Vapor supply line 44 is connected into output line 34 after being routed through heat exchanger 32, a relatively small compressor 46 being provided to insure flow from line 44 into the relatively high pressure output line 34 in the event the expansion occurring within heat exchanger 32 does not provide adequate pressure to overcome the pressure in line 34. Those skilled in the art who have the benefit of this disclosure will recognize that under normal operating conditions, compressor 46 will run only intermittently.

[0020] A return line 48 and appropriate valves (not numbered) arc provided in each section of the lines connecting storage tank 10 to CNG tank 36, as is a safety valve 50 and appropriate controls (not shown), all as known in the art. Likewise, appropriate controls, instrumentation, and sensors/monitors are provided to insure safe operation of the LNG vaporizer of the present invention.

[0021] Those skilled in the art who have the benefit of this disclosure will also recognize that changes can be made to the component parts of the of the present invention without changing the manner in which those component parts function and/or interact to achieve their intended result. All such changes, and others that will be clear to those skilled in the art from this description of the preferred embodiment(s) of the invention, are intended to fall within the scope of the following, non-limiting claims.