Apparatus for measuring impurity concentrations in a liquid

• US 5,098,657 A
• Filed: 08/07/1989
• Issued: 03/24/1992
• Est. Priority Date: 08/07/1989
• Status: Expired due to Term

• Current Assignee: TSI Incorporated
• Original Assignee: TSI Incorporated
• Inventors: Kerrick, Thomas A., Quant, Frederic R., Havir, Darrell D., Blackford, David B., Sem, Gilmore J.
• Primary Examiner(s): Lacey, David L.
• Assistant Examiner(s): Redding, David
• Application Number:
  US07/390,282
• Time in Patent Office: 960 Days
• Field of Search: 356/37, 356/335-337, 436/36, 422/73, 422/110, 422/112, 422/115, 377/11, 377/12, 239/74, 239/19, 137/115
• US Class Current: 422/73
• CPC Class Codes: B03C 2201/04 Ionising electrode being a wire
• CPC Class Codes: B03C 3/017 Combinations of electrostatic separation with other processes, not otherwise provided for
• CPC Class Codes: B03C 3/09 characterised by presence of stationary flat electrodes arranged with their flat surfaces at right angles to the gas stream
• CPC Class Codes: B03C 3/12 characterised by separation of ionising and collecting stations
• CPC Class Codes: B03C 3/38 Particle charging or ionising stations, e.g. using electric discharge, radioactive radiation or flames
• CPC Class Codes: B03C 3/47 flat, e.g. plates, discs, gratings
• CPC Class Codes: G01N 15/065 using condensation nuclei counters
• CPC Class Codes: G01N 15/0656 using electric, e.g. electrostatic methods or magnetic methods by investigating individual particles G01N15/1031, G01N15/12

Abstract

An apparatus for measuring nonvolatile residue concentrations in liquid is disclosed. A plurality of fixed and adjustable flow restrictive elements are utilized and arranged in-line from a fluid supply source to provide a constant, pressure controlled flow of liquid to the measuring apparatus and allow for real-time measurements and optimal concentration detection. An atomizer atomizes the liquid into droplets which are dried to nonvolatile residue particles. The nonvolatile residue particle concentration is then determined utilizing an electrostatic aerosol detector. The invention further discloses apparatus for collecting a sample of nonvolatile residue for analysis and identification using a corona precipitator.

Claims

1. An apparatus for measuring residue particles in a fluid, comprising:

(a) an atomizer for atomizing a fluid;

(b) means cooperatively connected to said atomizer for drying atomized fluid to produce residue particles;

(c) delivery means, cooperatively connected to said atomizer, for placing the fluid in fluid communication with said atomizer at a constant flowrate, said delivery means including a first orifice, a second orifice, a pressure sensor and control valve means, wherein said sensor is constructed and arranged so as to measure the fluid pressure between said first orifice and said control valve means and generate a first signal indicative thereof, and wherein said control valve means is positioned and arranged so as to respond to said generated signal and maintain the liquid pressure at a predetermined value to said second orifice, and

(d) means for counting the residue particles connected in flow communication with said drying means.

2. The apparatus of claim 1 wherein said pressure sensor includes:

(a) a pressure transducer constructed so as to measure the fluid pressure between said first orifice and said control valve means and for producing said first signal;

(b) an analog to digital converter, cooperatively connected to said transducer, constructed so as to produce a second signal responsive to said first signal;

(c) a microprocessor operatively connected to said analog to digital converter constructed so as to compare said second signal with a predetermined value and producing an error signal; and

(d) means for adjusting said control valve means, said adjusting means operatively connected to said microprocessor and said control valve means, said adjusting means being responsive to said error signal, whereby said control valve means maintains the measured fluid pressure at a predetermined value.

3. The apparatus of claim 1 further including at least one diffusion screen, said diffusion screen operatively connected to said counting means and constructed so as to alter the operating range of the apparatus for measuring residue.

4. An apparatus for measuring nonvolatile residue particles in a liquid, comprising:

(a) an atomizer for atomizing liquid and producing droplets;

(b) an evaporator in flow communication with said atomizer for evaporating the droplets into residue particles;

(c) a condensation nucleus counter in flow communication with said evaporator for counting the residue particles; and

(d) means for controlling the flow rate of the liquid to the atomizer in flow communication with said atomizer, including a first and second orifice in fluid communication with one another, a pressure sensor and a control valve means, a processing means connected to said pressure sensor and said control valve means, said control valve means in fluid communication between said first and second orifices so as to respond to signals generated from said processing means, wherein said sensor is positioned and arranged to measure the liquid pressure between said first orifice and said second orifice and the pressure measurements are provided to said processing means, and wherein variations of the pressure are automatically compensated for by said processing means so as to provide constant liquid delivery to the atomizer, said control valve means in flow communication with a fluid disposal means for disposing fluid, wherein when the pressure is above a predetermined value, said processing means provides a signal to said control valve means which opens allowing more fluid to flow into said fluid disposal means and when the pressure is below a predetermined value, said processing means provides a signal to said control valve means which closes allowing less fluid to flow into said disposal means.

5. A nonvolatile residue particle analyzer in combination with an atomizer and a liquid supply, said atomizer in flow communication with said liquid supply which is constructed to atomize the liquid in said supply into droplets which are subsequently dried to nonvolatile residue particles in an evaporator which is in flow communication with said atomizer, the residue particles being counted by a counting means connected to said evaporator, said combination further comprising:

(a) first fluid restrictive means, in fluid communication with the liquid supply, for producing an approximate flow rate;

(b) second fluid restrictive means, arranged and configured in fluid communication with said first fluid restrictive means, for restricting fluid flow to the atomizer; and

(c) variable fluid restriction control means, located in fluid communication between said first and second fluid restrictive means and responsive to variations in the liquid pressure between said first and second fluid restrictive means, for compensating for changes in the pressure variations, whereby variations of the pressure are automatically compensated for so as to provide constant fluid delivery to the atomizer.

6. A fluid delivery apparatus in combination with a liquid supply and an atomizer constructed so as to atomize the liquid in the supply into droplets, said combination further comprising:

(a) first fluid restrictive means, in fluid communication with the liquid supply, for producing an approximate flowrate;

(b) second fluid restrictive means, arranged and configured in fluid communication with said first fluid restriction means, for restricting fluid flow to the atomizer; and

(c) variable fluid restriction control means in fluid communication between said first and second fluid restrictive means and responsive to fluctuations in fluid pressure between said first fluid restrictive means and said second fluid restrictive means, for automatically compensating for fluctuations in the fluid pressure, wherein variations in the fluid pressure are automatically compensated for so as to provide constant fluid delivery to the atomizer.

7. The apparatus of claim 6, wherein said first and second restrictive means include orifices.

8. The apparatus of claim 7, wherein said first and second fluid restrictive means are made of sapphire.

9. The apparatus of claim 6, wherein said variable restrictive control means includes a pressure sensor and a control valve means wherein said sensor is constructed so as to measure said fluid pressure between said first fluid restrictive means and said second fluid restrictive means and generate a first signal indicative thereof, and wherein said control valve means responds to said generated signal to maintain said fluid pressure at a predetermined value.

10. An apparatus for measuring the nonvolatile residue concentration of a fluid, comprising:

(a) an atomizer for mixing the fluid with clean air or nitrogen to produce droplets having a constant size distribution;

(b) an evaporator connected to said atomizer for evaporating the droplets leaving residue particles;

(c) first fluid restrictive means for producing an approximate flowrate of the fluid;

(d) second fluid restrictive means, located in fluid communication downstream from said first fluid restrictive means, for restricting fluid flow to the atomizer;

(e) variable fluid restriction control means, located in fluid communication between said first and second fluid restrictive means and responsive to pressure between said first fluid restrictive means and said second fluid restrictive means and for compensating for changes in the pressure;

whereby variations of the pressure are automatically compensated for so as to provide constant fluid delivery to the atomizer; and

(f) measuring means, connected in fluid communication with said evaporator, for measuring the concentration of the detectable nonvolatile residue particles.

11. The apparatus of claim 10 wherein said first and second fluid restrictive means include orifices.

12. The apparatus of claim 11, wherein said first and second fluid restrictive means are made of sapphire.

13. The apparatus of claim 10, wherein said variable restrictive control means includes a pressure sensor and a control valve means, wherein said sensor is positioned and arranged so as to measure the pressure between said first fluid restrictive means and said second fluid restrictive means and generate a first signal indicative thereof, so that said control valve means responds to said generated signal to maintain said fluid pressure at a predetermined value.

14. The apparatus of claim 10 wherein said means for measuring the concentration of residue particles includes a condensation nucleus counter.

15. The apparatus of claim 10, further including means for collecting the residue particles for identification, said collecting means in fluid communication with said measuring means.

16. The apparatus of claim 15, wherein said means for collecting the residue particles is a corona precipitator.

17. The apparatus of claim 10, further including a means for draining the non-atomized fluid from said atomizer and said variable fluid control restriction means.

18. The apparatus of claim 17, wherein said means for draining includes a material which provides an air tight seal while allowing fluid to drain, a means for collecting the fluid and a means for disposing of the fluid.

19. The apparatus of claim 18, wherein said material is a natural sponge.