US 3885437 A
Effluent discharging into the atmosphere from dry exhaust stacks is sampled by employing an effluent-gathering probe capable of obtaining representative samples of the total effluent exhausted through the stack. The probe travels on two axes in a cross sectional plane of the stack so as to move the probe in a spiral path across the radius of the stack to obtain homogeneous samples of the exhaust emissions.
Description (OCR text may contain errors)
United States Patent [1 1 [111 3,885,437 Reagan May 27, 1975 DEVICE FOR SAMPLING EXHAUST STACK EFFLUENT Primary Examiner-James J. Gill Assistant Examiner-Anthon V. Ciarlante  Inventor Paul Reagan Kingston Tenn Attorney, Agent, or F [rm-Jahres E. Denny; David S.  Assignee: The United States of America as Zachry; Earl L. Larcher represented by the United States Energy Research and Development Administration, Washington, DC.  ABSTRACT  Filed: Feb. 26, 1974 Effluent discharging into the atmosphere from dry ex- PP 9 haust stacks is sampled by employing an effluentgathering probe capable of obtaining representative [52 US. Cl 73/421.5 A Samples the total effluhht exhausted thmugh the 51 Int. Cl 001 1/24; GOln 1/26 stack- The Probe travels on two axes a cross  Field of Search 73/4215 A 4215 R 422 R tional plane of the stack so as to move the probe in a spiral path across the radius of the stack to obtain ho-  References Cited mogeneous samples of the exhaust emissions.
UNITED STATES PATENTS 3 Claims, 2 Drawing Figures 2,926,527 3/1960 Crandall 73/4215 A 1 DEVICE FOR SAMPLING ExuAusT'sTA'c'i; r
EFFLUENT l The present invention relates generally to sampling exhaust stack effluent, and more particularly to 'a mechanism for displacing an effluent-gathering probe to obtain homogeneous samples of: the effluen' t' throughout the entire cross section of the stack. This invention was made in the course of, or under, a contract with the United States Atomic Energy Commis- SlOn.
Regulation of the quantity and types of effluent discharged into the atmosphere has been a major pollution control problem. A considerable percentage of this air-borne pollution is discharged from dry stacks. The effluentemanating from such stacks has been brought under control to a significant extent by using various precipitators and dust collecting systems; however, it is application in practical use to thereby enable others skilled in the art to best utilize the invention in various embodiments and modifications as are best adapted to the particular use contemplated.
Described generally, the efflluent-sampling apparatus of the present invention is of the type in which a vacuum operated probe is placed within a dry exhaust stack or conduit for intercepting and capturing a portion of the effluent passing through the conduit and conveying the captured effluent to a suitable container for subsequent analyses. Such containers include filters for removing the particulate matter from the captured effluent as are well known in the art. The improvement still necessary to monitor the actual discharge of the material into the atmosphere to insure that the effluent collecting systems are in proper working order. The accuracy in obtaining these measurements is substantially dependent upon gathering representative samples of the effluent being discharged. If the velocity, particle concentration, and path profiles of the exhaust gases were homogeneous across the exhaust stack, then such representative samples could be readily obtained. However, such ideal conditions seldom exist since the normal conditions within the exhaust stack show that the velocity and concentration of the dust particles vary significantly from point to point throughout any given cross section of the stack.
Accordingly, it is the primary aim or objective of the present invention to provide a device for gathering representative samples of the exhaust effluent throughout the entire cross section of a dry exhaust stack. This apparatus comprises a fixture disposed within the stack, a tubulation supported by the fixture and projecting along the longitudinal axis of the stack, a rotatable shaft disposed within the tubulation, an arm secured to the shaft and extending in a direction orthogonal to the latter with this arm having a length substantially corresponding to the radius of the stack and displaceable in a cross sectional plane of the latter in response to shaft rotation, slide means carried by the arm, an effluentgathering means affixed to the slide means, gear means coupling the slide means to the tubulation for effecting displacement of the effluent-gathering means along the arm in response to rotation of the shaft.
Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.
In the accompanying drawing,
FIG. 1 is a vertical section view of an exhaust stack showing the present effluent-gathering probe of the present invention; and
FIG. 2 is a fragmentary view taken along lines 2-'-2 of FIG. 1 showing the paths of the probe within the exhaust stack.
A preferred embodiment of the invention has been chosen for the purpose of illustration and description, The preferred embodiment illustrated is not intended to be exhaustive or to limit the invention to the precise form disclosed. It is chosen and described in order to best explain the principles of the invention and their rangements aspreviously known involves an arrangement wherein the probe is moved across the radius of the conduit while being rotated about the longitudinal axis of the conduit so as to generate a sample-gathering path defined by an archimedean spiral.
As shown in the drawing, the present invention is disposed in a dry exhaust stack 10 wherein the effluent travels in the direction shown by arrow 11. A frame or fixture 12 is placed within the exhaust stack 10 for'supporting the probe-moving device of the present invention. This frame 12 is of a construction which provides minimal resistance to the flow of the exhaust gases. A sleeve or tubulation 14 is fixed to the frame and projects from the latter along a path corresponding to the longitudinal axis of the exhaust stack 10. This tubulation, in turn, houses a rotatable shaft 16 which is driven by a suitable drive motor, e.g., a hydraulic, pneumatic, or electrical motor supported by the frame, as shown at 18. The shaft 16 projects beyond the lowermost end of the tubulation l4 and is coupled to a flange-like structure 20 which has a portion thereof projecting in a vertical direction parallel to the shaft but radially offset therefrom as shown. An arm 22 is secured to the offset portion of the flange and projects in a direction orthogonal to the axes of the shaft 16 to a location adjacent to the interior wall of the stack so as to span essentially the entire radius of the stack. The arm 22 is provided at the end thereof remote to the flange 20 with a block-like structure 23 which, together with the flange, provides support for a worm gear 24. The worm gear is rotatably disposed at one end thereof in block 23 while the other end of the worm gear ex tends through and is rotatably carried by the offset portion of the flange 20. The worm gear 24, in turn, supports a coneshaped probe 26 having a suitable opening at one end thereof facing upstream with respect to the direction of the effluent discharge. The probe 26 threadedly engages the worm gear 22 so that rotation of the latter will move the probe along the worm gear in either direction so as to traverse the radius of the exhaust stack. The worm gear .24 is provided with the suitable well-known direction-changing devices contiguous to the block 23 or the flange 20 for reversing the direction of probe travel.
To provide rotation of the worm gear 24 for displacing the probe 26, a bevel gear 28 is affixed to the end of the worm gear projecting through the flange 20. This gear 28 is in mesh with a stationary bevel gear 30 affixed to the tubulation 14 so that'upon rotation of the shaft 16, flange 20 rotates about the axis of the stack, with this latter rotation causing the bevel gear to rotate the worm gear 24. Thus, as shaft 16 rotates to move the probe in a radial direction through the rotation of the worm gear 24, the probe is also driven about the longitudinal axis of the exhaust stack to generate a spiral path about the cross section of the exhaust stack as generally shown by the arrows in FIG. 2. In order to insure the desired exposure of the probe to the effluent, the distance between adjacent teeth on the worm gear or the rotational velocity of the probe may be selectively varied. The effluent gathered by the probe is conveyed to a suitable container, not shown, by coupling the probe to a suitable vacuum source, not shown, as is well known in the art. The vacuum line 32 coupling the probe to the vacuum source preferably extends through the shaft 16 to assure that the line does not in terfere within the movement of the probe.
As various changes may be made in the form, construction, and arrangement of the parts herein without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in a limiting sense.
What is claimed is:
1. An apparatus for obtaining a substantially homogeneous sampling of an effiuent stream flowing through an elongated dry stack, comprising a fixture disposed within said stack, a tubulation supported by said fixture and projecting along the longitudinal axis of the stack, a rotatable shaft disposed within said tubulation, an arm secured to said shaft and extending in a direction orthogonal to the latter with said arm having a length substantially corresponding to the inner radius of said stack and displaceable in a cross-sectional plane of the latter in response to shaft rotation, slide means carried by said arm, an effluent-gathering means affixed to said slide means, gear means coupling said slide means to said tubulation for effecting displacement of said effluent-gathering means along said arm in response to rotation of said shaft.
2. The apparatus claimed in claim 1, wherein said arm and said effluent-gathering means are displaced simultaneously for driving said effluent-gathering means along a path defined by an archimedean spiral.
3. The apparatus claimed in claim 2, wherein said slide means is a worm gear, said effluent-gathering means is a probe having an effluent-receiving opening at one end thereof and coupled to a vacuum source, and said gear means comprises a stationary bevel gear affixed to said tubulation and a rotatable bevel gear affixed to said worm gear and in mesh with said station-