Compressors for natural gas and related devices, systems, and methods
A natural gas compressor can include a pre-staging chamber that couples with a supply line to receive natural gas from the supply line. The compressor can additionally include a first-stage chamber that couples with the supply line to receive natural gas from the supply line. The first-stage chamber can additionally be coupled with the pre-staging chamber to receive from the pre-staging chamber natural gas that has been compressed by the pre-staging chamber. The compressor can also include a second-stage chamber configured to receive natural gas that has been compressed by the first-stage chamber.
1. A natural gas compressor assembly comprising:
a pre-staging chamber configured to be coupled to a supply line to receive natural gas directly and only from the supply line;
a first-stage chamber configured to be coupled to the supply line to receive natural gas from the supply line and coupled with the pre-staging chamber to receive natural gas compressed by a first amount from the pre-staging chamber such that the natural gas compressed in the pre-staging chamber is received by the first-stage chamber separately from the natural gas received by the supply line and is selectively delivered from the pre-staging chamber to the first-stage chamber;
a second-stage chamber configured to receive natural gas only from the first-stage chamber after the natural gas has been compressed by a second amount in the first-stage chamber;
a drive shaft; and
a plurality of pistons comprising a first piston and a second piston, wherein the first piston and the second piston are attached to the drive shaft, wherein the first piston and the second piston remain at a constant distance from each other, wherein the pre-staging chamber is defined at one end by the first piston and at an opposing end by the second piston, wherein a stroke length of the drive shaft in a first direction is the same as a stroke length of the drive shaft in a second direction, and wherein the first piston moves in tandem with the drive shaft to alter a size of the first-stage chamber, wherein the second piston moves in tandem with the drive shaft to alter a size of the second-stage chamber, and wherein a maximum volume of the first-stage chamber is greater than a maximum volume of the second-stage chamber;
wherein the pre-staging chamber and the second-stage chamber decrease in size and the first-stage chamber increases in size as the drive shaft moves in the first direction; and
wherein the pre-staging chamber and the second-stage chamber increase in size and the first-stage chamber decreases in size as the drive shaft moves in the second direction.
2. The assembly of claim 1 , wherein a ratio of the maximum volume of the first-stage chamber to the maximum volume of the second-stage chamber is such that the same amount of work is performed in moving the drive shaft through a full stroke length in the first direction as is performed in moving the drive shaft through a full stroke length in the second direction.
3. The assembly of claim 1 , wherein, the pre-staging chamber is physically between the first-stage chamber and the second-stage chamber.
4. The assembly of claim 1 , wherein the first amount by which natural gas is compressed in the first-stage chamber is less than the second amount by which natural gas is compressed in the second-stage chamber.
5. The assembly of claim 1 , further comprising a valve configured to selectively permit natural gas to flow from the pre-staging chamber to the first-stage chamber.
6. The assembly of claim 5 , wherein the valve is a one-way valve in the first piston, and wherein the one-way valve is configured to prevent gas from flowing from the first-stage chamber into the pre-staging chamber.
7. The assembly of claim 6 , wherein the one-way valve comprises a reed valve.
8. The assembly of claim 5 , wherein the valve is a controlled valve that is configured to selectively permit natural gas to flow from the pre-staging chamber to the first-stage chamber when the a pressure of the natural gas in the pre-staging chamber is greater than a pressure of the natural gas in the first-stage chamber and when the valve has been actuated to an open state.
9. The assembly of claim 8 , wherein the controlled valve is configured to be in an open state when the drive shaft moves in the first direction and is configured to be in a closed state when the drive shaft moves in the second direction.
10. The assembly of claim 8 , wherein the valve is controlled by an electronic controller.
11. The assembly of claim 1 , wherein at one or more stages of operation of the assembly, a sleeve defines at least a portion of each of the pre-staging chamber and the first-stage chamber.
12. The assembly of claim 11 , wherein the assembly is configured to draw natural gas from the supply line into the sleeve when the drive shaft moves in each of the first and second directions.