Variable restrictor and method

• US 5,694,973 A
• Filed: 01/09/1995
• Issued: 12/09/1997
• Est. Priority Date: 01/09/1995
• Status: Expired due to Term

• Current Assignee: Waters Technologies Corporation (Waters Corporation)
• Original Assignee: Lalit M. Chordia
• Inventors: Chordia, Lalit M.
• Primary Examiner(s): NGUYEN, HOANG M
• Application Number:
  US08/370,483
• Time in Patent Office: 1,065 Days
• Field of Search: 137/487.5, 137/341, 251/218, 251/368, 251/129.11, 251/36
• US Class Current: 137/341
• CPC Class Codes: F16K 1/38 of conical shape
• CPC Class Codes: F16K 1/422 attachable by a threaded connection to the housing
• CPC Class Codes: Y10T 137/6606 With electric heating element
• CPC Class Codes: Y10T 137/7761 Electrically actuated valve

Abstract

A variable restrictor. The variable restrictor is comprised of a housing having a high pressure inlet. The housing also has a channel connected to the high pressure inlet. The housing also has a low pressure outlet connected to the channel with the channel disposed between the high pressure inlet and the low pressure outlet. The variable restrictor is also comprised of a mechanism for reducing supercritical fluid at a pressure between 100-12,000 psi from the high pressure inlet to a pressure between 0-800 psi from the low pressure outlet. The reducing mechanism is disposed in the housing and is in contact with the low pressure outlet. Additionally, the variable restrictor is comprised of a pressure transducer disposed in the housing and in contact with the channel to sense the pressure in the channel. A method for restricting fluid comprising the steps of introducing high pressure fluid at a pressure between 100-12,000 psi into a high pressure port of a housing. Next, there is the step of reducing the pressure of the fluid in the high pressure port to a pressure between 0-800 psi as it flows through a channel connected to the high pressure port with a needle of a needle assembly. Then there is the step of sensing the pressure of the fluid with a pressure transducer connected directly to the channel after the pressure of the fluid has been reduced. Next there is the step of moving the needle of the needle assembly to reduce the pressure of the fluid a desired amount based on the pressure sensed in the channel. Then there is the step of flowing the fluid after its pressure has been reduced through a seat channel of a seat made of sapphire. Then there is the step of releasing the fluid through a low pressure outlet port of the housing.

Claims

1. A variable restrictor comprising:

a housing having a high pressure inlet, a channel connected to the high pressure inlet, and a low pressure outlet connected to the channel with the channel disposed between the high pressure inlet and low pressure outlet;

a mechanism for reducing supercritical fluid at a pressure between 100-12,000 psi from the high pressure inlet to a pressure between than 0-800 psi from the low pressure outlet, said reducing mechanism disposed in the housing and in contact with the low pressure outlet;

a mechanism for providing heat to the channel, said providing mechanism in thermal communication with the channel so the fluid does not solidify as its pressure is reduced;

a pressure transducer disposed in the housing and in contact with the channel to sense the pressure in the channel; and

a controller for controlling the reducing mechanism based on the pressure in the channel sensed by the pressure transducer, said controller connected to the pressure transducer and the reducing mechanism.

2. A variable restrictor as described in claim 1 wherein the pressure transducer is in contact with the channel and disposed downstream of the reducing mechanism.

3. A variable restrictor as described in claim 2 including a temperature sensor connected to the channel to sense the temperature in the channel.

4. A variable restrictor as described in claim 3 including a controller connected to the pressure transducer, the temperature sensor and the reducing mechanism to control the reducing mechanism as a function of the temperature and the pressure of the channel to cause the pressure of fluid from the high pressure inlet to reduce to a desired lower pressure in the low pressure outlet.

5. A variable restrictor as described in claim 4 said reducing mechanism having a needle assembly with a needle made of sapphire or alumina oxide ceramic that extends into the channel to reduce the pressure of fluid in the high pressure inlet to a lower pressure as the fluid passes through the channel.

6. A variable restrictor as described in claim 5 wherein the reducing mechanism includes a motor connected to the needle assembly for moving the needle of the needle assembly in the channel.

7. A variable restrictor as described in claim 6 including a seat made of sapphire or having a seat channel, said seat disposed in the housing downstream of the reducing mechanism, said seat channel connected with the channel and the low pressure outlet so fluid from the channel passes through the seat channel and to the low pressure outlet.

8. A variable restrictor as described in claim 7 wherein said housing has a needle assembly port needle assembly disposed in the needle assembly port, said needle assembly having a spring loaded seal which seals the needle in the housing so no fluid can escape by flowing out the needle assembly port.

9. A method for restricting fluid comprising the steps of:

introducing high pressure fluid at a pressure between 100-12,000 psi into a high pressure port of a housing;

reducing the pressure of the fluid in the high pressure port to a pressure between 0-800 psi as it flows through a channel connected to the high pressure port with a needle of a needle assembly while heat is applied to channel so the fluid does not solidify as its pressure is reduced;

sensing the pressure of the fluid with a pressure transducer connected directly to the channel after the pressure of the fluid has been reduced;

moving the needle of the needle assembly to reduce the pressure of the fluid a desired amount based on the pressure sensed in the channel;

flowing the fluid after its pressure has been reduced through a seat channel of a seat made of sapphire; and

releasing the fluid through a low pressure outlet port of the housing.

10. A variable restrictor comprising:

a housing having a high pressure inlet, a channel connected to the high pressure inlet, and a low pressure outlet connected to the channel with the channel disposed between the high pressure inlet and low pressure outlet;

a pressure transducer disposed in the housing and in contact with the channel to sense the pressure in the channel;

a mechanism for reducing supercritical fluid at a pressure between 100-12,000 psi from the high pressure inlet to a pressure between 0-800 psi from the low pressure inlet, said reducing mechanism disposed in the housing and in contact with the low pressure outlet, said reducing mechanism having a needle assembly with a needle made of a material having a surface smoothness between 0.001 to 1 microns, a hardness of 4-20 mohs, a coefficient of linear thermal expansion of 0-20×

10^-6 /°

C. and a thermal conductivity of 10-100 W/M-K that extends into the channel to reduce the pressure of fluid in the high pressure to a lower pressure as the fluid passes through the channel, said reducing mechanism having a mechanism for providing heat to the channel so the fluid does not solidify as its pressure is reduced, said providing mechanism in thermal communication with the channel; and

a controller for controlling the reducing mechanism based on the pressure in the channel sensed by the pressure transducer, said controller connected to the pressure transducer and the reducing mechanism.

11. A variable restrictor as described in claim 10 wherein the reducing mechanism includes a motor connected to the needle assembly for moving the needle of the needle assembly in the channel.

12. A variable restrictor as described in claim 11 wherein the material of the needle is sapphire or alumina oxide ceramic.

13. A variable restrictor comprising:

a housing having a high pressure inlet, a channel connected to the high pressure inlet, and a low pressure outlet connected to the channel with the channel disposed between the high pressure inlet and low pressure outlet;

a pressure transducer disposed in the housing and in contact with the channel to sense the pressure in the channel;

a mechanism for reducing supercritical fluid at a pressure between 100-12,000 psi from the high pressure inlet to a pressure between 0-800 psi from the low pressure inlet, said reducing mechanism disposed in the housing and in contact with the low pressure outlet, said reducing mechanism having a mechanism for providing heat to the channel so the fluid does not solidify as its pressure is reduced, said providing mechanism in thermal communication with the channel;

a seat made of a material having a surface smoothness between 0.001 to 1 microns, a hardness of 4-20 mohs, a coefficient of linear thermal expansion of 0-20×

10^-6 /°

C. and a thermal conductivity of 10-100 W/M-K having a seat channel, said seat disposed in the housing downstream of the reducing mechanism, said seat channel connected with the channel and the low pressure outlet so fluid from the channel passes through the seat channel and to the low pressure outlet; and

a controller for controlling the reducing mechanism based on the pressure in the channel sensed by the pressure transducer, said controller connected to the pressure transducer and the reducing mechanism.

14. A variable restrictor as described in claim 13 wherein the material of the seat is sapphire or alumina oxide ceramic.

15. A variable restrictor comprising:

a housing having a high pressure inlet, a channel connected to the high pressure inlet, and a low pressure outlet connected to the channel with the channel disposed between the high pressure inlet and low pressure outlet;

a pressure transducer disposed in the housing and in contact with the channel to sense the pressure in the channel;

a mechanism for reducing supercritical fluid at a pressure between 100-12,000 psi from the high pressure inlet to a pressure between 0-800 psi from the low pressure inlet, said reducing mechanism disposed in the housing and in contact with the low pressure outlet, said housing having a needle assembly port, said reducing mechanism having a needle assembly with a needle that extends into the channel to reduce the pressure of fluid in the high pressure to a lower pressure as the fluid passes through the channel, said needle assembly disposed in the needle assembly port, said reducing mechanism having a spring loaded seal which seals the needle in the housing so no fluid can escape by flowing out the needle assembly port, said reducing mechanism having a mechanism for providing heat to the channel so the fluid does not solidify as its pressure is reduced, said providing mechanism in thermal communication with the channel; and

a controller for controlling the reducing mechanism based on the pressure in the channel sensed by the pressure transducer, said controller connected to the pressure transducer and the reducing mechanism.