Abstract:
A sample handling system includes an inlet for receiving sample from a process, and a mixer for intermixing a solvent with the sample to dissolve undesirable components within a sample. A separator is provided that receives the solvent/sample mixture and separates the sample from the solvent and undesirable solutes. The so separated sample is then provided to a suitable analyzer for analysis.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    Process analytic systems are used in a variety of industries to measure process characteristics in substantially real-time. Such industries include the chemical, petrochemical, pipeline, and pharmaceutical industries. Process analytic systems are often used for process gas analysis, combustion analysis and control, and emissions monitoring in any of the above industries.  
           [0002]    Process analytic systems differ substantially from laboratory analyzers in the manner in which sample handling is effected. For example, samples are usually held as a gas or liquid in an appropriate container that is transported, sometimes by hand, to a laboratory analytical instrument. In contrast, the process analytic system receives its sample directly from a sampling point in the process, without human assistance. Process analytic systems can include a process analyzer and a process sample handling system.  
           [0003]    For a process analyzer in a process analytic system, such as a process gas chromatograph, to provide an accurate analysis of the process, it is important to convey the sample from the process to the analyzer such that the sample is representative of the process. Since any number of variables can affect the extent to which the sample represents the process, it is desirable to control many variables including temperature, pressure and flow while conveying the sample to the analyzer. Further complicating matters is the fact that the sample may be quite hot and under considerable pressure, contain water vapor, solids, condensed liquid, acids and/or other substances, etc. One example of a known process analyzer is the Continuous Analyzer Transmitter, available from Rosemount Analytical, Inc., of Anaheim, Calif. Another example of a known process analyzer is the Model GCX Process Gas Chromatograph, available from Rosemount Analytical, Process Analytic Division, of Orrville, Ohio.  
           [0004]    A process sample handling system is utilized in a process analytic system to extract a process sample from a sampling point and convey the sample to a process analyzer. Generally, the sample handling system includes all requisite components to maintain a constant sample flow to the analyzer. Thus, the sample handling system generally includes suitable pressure reduction components, filters, vaporizers, flow controls, and sample switching or selector valves for introducing multiple sample streams or a calibration standard to the process analyzer. With the exception of vaporizers, filters, and pressure reducers, most components of the sample handling system are usually located near the process analyzer, and sometimes within the same housing as the analyzer. The process sample handling system is an important component of an effective process analytic system. If the process sample is not delivered to the process analyzer in a condition that is representative of the process, errors will occur in the analysis. Many of the problems encountered in process analytic systems can be traced to a problem occurring in the process sample handling system.  
           [0005]    Many industrial samples encountered by the sample handling system contain a number of substances which are not of interest, but which nonetheless may not only adversely affect accuracy of the analysis, but also accelerate deterioration of the sample handling system and/or associated analyzer. Examples of such substances include hydrochloric acid (HCL), chlorine gas, sulfuric acid (H 2 SO 4 ), as well as various solids. These substances not only reduce the quality of analysis, but also cause accelerated deterioration on the process analytic system itself. A system which could ameliorate the effects of such substances on both analyses and analytic system itself, would be highly beneficial to the act of process analysis.  
         SUMMARY OF THE INVENTION  
         [0006]    A sample handling system includes an inlet for receiving sample from a process, and a mixer for intermixing a solvent with the sample to dissolve undesirable components within a sample. A separator is provided that receives the solvent/sample mixture and separates the sample from the solvent and undesirable solutes. The so separated sample is then provided to a suitable analyzer for analysis. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a diagrammatic view of a process analytic system in accordance with an embodiment of the present invention.  
         [0008]    [0008]FIGS. 2 and 3 are diagrammatic views of a sample probe in accordance with embodiments of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0009]    [0009]FIG. 1 is a diagrammatic view of a sample handling system for measuring carbon monoxide and oxygen in accordance with embodiment of the present invention. Although the system shown in FIG. 1 will be described with respect to a specific solvent (water) and water-soluble substances, it is expressly contemplated that other solvent/solute combinations can be used in accordance with embodiments of the present invention.  
         [0010]    System  100  includes enclosure  102 , air inlet  104 , sample probe  106 , solvent inlet  108 , drain  110 , vent  112 , zero gas inlet  114 , span gas inlet  116  and  118 , and vent  120 . Sample probe  106  is generally disposed at or within a stack or process line and is adapted to receive a relatively small amount of sample from within the stack or process line. The sample is conveyed along line  124  into enclosure  102  and subsequently to four-way valve  126 . Preferably, line  124  is sized to have an outer diameter ranging from approximately 9.53 millimeters to approximately 12.7 millimeters. Additionally, it is preferred that line  124  be constructed from a corrosion resistant tubing and physically adapted to slope from stack or duct  122  toward the inlet of mixer  128 . Such sloping is illustrated diagrammatically by the diagonal line. In embodiments where sample handling system  100  will be exposed to subfreezing temperatures, line  124  can be provided with heating elements and insulation as desired. In FIG. 1, valve  126  is illustrated fluidically coupling sample probe  106  to mixer  128  (also referred to herein as jet pump  128 ). An alternate port coupling of valve  126  is shown with dashed lines wherein, upon actuation, dry instrument air is coupled to sample probe  106  to essentially provide a blow-back function. The blow-back airflow is determined in part by pressure regulator  130 . Pressure indicator  132  indicates the blow-back pressure as set by pressure regulator  130 .  
         [0011]    The pressure within sample line  124  downstream from valve  126  is indicated by pressure indicator  134 . Sample is provided to jet pump  128 , and optionally to jet pump  136  based upon actuation of shut-off valve  138 . Jet pump  128  receives solvent (water) from port  108  through shut-off valve  140 . The pressure of solvent provided to jet pump  128  is indicated by pressure indicator  142 . As illustrated, solvent in the preferred embodiment is water provided to port  108  at a pressure ranging between approximately 413 kpa to approximately 689 kpa at a rate of 5.7 liters per minute. Preferably, solvent is filtered at y-strainer  144  which provides filtered solvent on lines  146  and  148 . The solvent entering jet pump  128  actually causes jet pump  128  to draw sample from the process. The exhaust of jet pump  128  is provided on line  150  and generally consists of a mixture of solvent and sample that flows to gas/liquid separator  152  where gas is separated from the solvent (water or steam). In embodiments where the solvent is steam or water, this process removes particulate and undesirable corrosive water-soluble components, such as SO 2 , SO 3 , NO x , HCL, H 2 SO 4 , CL 2 , etc.  
         [0012]    Sample is then provided from gas/liquid separator  152  to coalescing filter  154 . Coalescing filter  154  is preferably a 0.6 micron filter that further removes additional water or steam. The water or steam so removed by coalescing filter  154  is provided to drain  110  through shut-off valve  156 . The sample filtered by coalescing filter  154  is split at node  158  with some flow being provided to vent  120  through flow meter  160 , while other flow is provided to air-dryer  162 . As illustrated, air-dryer  162  receives dry instrument air, the pressure of which is controlled by pressure regulator  164  (indicated by pressure indicator  166 ), and the flow rate of which is determined by flow meter  168 . Essentially, dry instrument air interacts with the filtered sample stream in dryer  162  to thereby further dry the sample stream. Dry instrument air continues on through dryer  162  and out vent  112 . Preferably, dryer  162  is a commercially available, such as those sold by Perma Pure Inc., of Toms River, N.J. The sample stream flowing from dryer  162  is split at node  170  with some sample flowing into five-way manual valve  172  and some sample flowing into five-way manual valve  174 . When five-way manual valve  172  is suitably actuated, sample flows through flowmeter  176  and guard filter  178  into carbon monoxide detector  180 . Carbon monoxide detector  180  provides an output (not shown) that is indicative of the quantity of carbon monoxide flowing therethrough.  
         [0013]    In a similar fashion, when five-way manual valve  174  is suitably actuated, sample flows through flowmeter  182 , through guard filter  184  and into oxygen detector  186 . Oxygen detector  186  provides an output (not shown) that is indicative of quantitative oxygen content in the sample stream.  
         [0014]    Those skilled in the art will recognize that while not necessary for practicing embodiments of the present invention, the provision of jet pump  136  reduces sample lag time through the system. In preferred embodiments, this lag time is reduced to less than 10 seconds per 100 feet using a 9.53 millimeter outside diameter sample line. Those skilled in the art will also recognize that by suitably adjusting flow meters  160 ,  176  and  182  adjustment for sample flow rate and system lag time are provided.  
         [0015]    Zero gas is provided through port  114  to five-way manual valve  172  while span gas (CO) is provided through inlet  118  to five-way manual valve  172 . In this manner, manual actuation of valve  172  can fluidly couple either zero gas or span gas to detector  180  for calibration and diagnostics. Similarly, zero gas is also provided to five-way valve  174 , while span gas (O 2 ) is provided through inlet  116  to five-way manual valve  174 . Thus, actuation of valve  174  can selectively couple zero gas, or span gas to oxygen detector  186  for calibration and/or diagnostics.  
         [0016]    It is preferred that materials in contact with the sample be selected to withstand such contact. Suitable materials include stainless steel, polytetrafluoroethylene, polycarbonate, bun-N polypropylene, and polyvinyl chloride. Further still, it is preferred that the sample probe  106  is constructed from an open tube of material such as Hastelloy C alloy available from Haynes International Inc., of Kokomo Ind., or  316  stainless steel.  
         [0017]    [0017]FIG. 2 illustrates sample probe  106  configured to obtain a sample from an environment that generally has a number of solids mixed with the sample. Such environments include, but are not limited to, glass furnaces, cement plants, and lime kilns. Probe  106  is passes through stack or duct wall  122  at such an angle θ (theta) which is selected to be between about 120 and 135 degrees. Probe  106  also includes solvent inlet  200 , which is coupleable to a source of solvent, preferably water, to allow the solvent to intermix with sample within probe  106  while also cooling probe  106 . Due to the angle at which probe  106  is disposed, excess solvent will drain from probe tip  202  along with undesirable solids by virtue of gravity.  
         [0018]    [0018]FIG. 3 is a more detailed diagrammatic view of probe  106  in accordance with embodiments of the present invention. Probe  106  includes flange  204  for mounting to a process stack or duct wall. Probe  106  includes couplings  206 ,  208  and  210 , for solvent, gas out, and gas in, respectively. A source of solvent, not shown in FIG. 3, is connected to coupling  206  such that solvent is passed through probe  206  ultimately emerging from spray nozzle  212 . Preferably the path of solvent through probe  106  is somewhat circuitous to allow the solvent to cool the probe, which may be exposed to sample temperatures easily ranging from less than 0 degrees Celsius to well over 1000 degrees C. As described above, it is advantageous to mix the incoming sample with a solvent, and nozzle  212  facilitates such function. Coupling  208  is a gas inlet for probe  108  and can be selectively coupled to a source of zero gas or span gas, as desired. Coupling  208  is a gas outlet that provides the sample and mixed solvent to the process instrument for analysis.  
         [0019]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.