CROSS-REFERENCE TO RELATED APPLICATIONS This application claims benefit to provisional patent application serial no.

62/418,916 (91 1 -027.1 -1 /N-OIC-0018US), filed 8 November 2016, which is incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1 . Field of Invention

This invention relates to a Total Organic Carbon (TOC) system for measuring organic contaminants in a water system; and more particularly relates to a main combustion furnace tube in such a TOC system.

2. Description of Related Art

One issue that is typical with all combustion Total Organic Carbon (TOC) systems is the expense and time involved in maintaining and or replacing the main combustion furnace tube. This is typically due to either chemical attack on the quartz tube material, or eventual structural failure of the tube due to direct exposure to the liquid sample injected. Thus, any design change that can extend the life of these expensive main furnace tubes can offer value to the customer, if it can be done easily and inexpensively.

In view of this, there is a need in the art for a better main combustion furnace tube. SUMMARY OF THE INVENTION

In summary, the invention utilizes a simple cylindrical tube, typically made of quartz, to serve as a sacrificial surface which the liquid sample can

preferentially attack, without interfering with the nominal performance of the TOC analyzer. The most basic and preferred version of the invention is a plain cylinder with openings on each end.

However, other versions of the design could utilize a closed, or semi- closed bottom, with or without ventilation holes and/or slits in the side walls of the cylinder.

The bottom of the cylinder could also be closed using a porous frit, again typically made of quartz. This would be an excellent solution, but at significant expense per part for this disposable guard tube.

According to some embodiments, and by way of example, the present invention may include, or take the form of, a furnace system, featuring a combination of a furnace, a main combustion furnace tube and a disposable guard tube.

The main combustion furnace tube may be configured to couple and extend from the furnace, having a zone for a combustion catalyst or high temperature support configured or formed therein.

The disposable guard tube may be coupled to the main combustion furnace tube, have a top opening configured to receive and have direct exposure to a liquid sample being injected into the main combustion furnace tube, and also have a bottom opening to provide the liquid sample to the main combustion furnace tube for processing in the zone for the combustion catalyst or high temperature support.

The furnace system may include one or more of the following additional features: The furnace system may include, or form part of, a total organic carbon (TOC) system for measuring organic contaminants in a water system.

The disposable guard tube may be a cylindrical tube made of quartz, or is made of a quartz tube material.

The disposable guard tube may include a closed or semi-closed bottom.

The closed or semi-closed bottom is configured or formed with ventilation holes.

The closed or semi-closed bottom may be configured or formed with slits in side walls of the cylindrical tube.

The closed or semi-closed bottom may be configured or formed using a porous frit, including made from quartz.

The porous frit may be a mixture of silica and fluxes that is fused at high temperature to make glass. BRIEF DESCRIPTION OF THE DRAWING

The drawing, which are not necessarily drawn to scale, includes Figures 1 - 6, as follows:

Figure 1 includes Figs. 1 A and 1 B, where Fig. 1 A shows a perspective view of a furnace system including a furnace having a main combustion tube with a disposable guard tube arranged thereon, and where Fig. 1 B shows a corresponding perspective view of the furnace system in Fig. 1 A, e.g., showing a partial exploded view of the main combustion tube and disposable guard tube above and outside of the furnace, all according to some embodiments of the present invention.

Figure 2 includes Figs. 2A, 2b and 2C, where Fig. 2A shows a perspective view of a main combustion tube with a disposable guard tube arranged thereon, where Fig. 2B shows a corresponding perspective view of the main combustion tube, the disposable guard tube arranged thereon, and a zone contained or formed therein for combustion catalyst or high temperature support, and Fig. 2C shows a

perspective view of the disposable guard tube shown in Figs. 2A and 2B, all according to some embodiments of the present invention.

Figure 3 includes Figs. 3A, 3B and 3C, where Fig. 3A shows a side view of a main combustion tube having a disposable guard tube arranged thereon with a frit coupled inside the bottom of the disposable guard tube, where Fig. 3B shows an exploded view of that shown in Fig. 3A with the main combustion tube and the disposable guard tube coupled together and the frit de-coupled from inside the bottom of the disposable guard tube, and Fig. 3C shows a bottom view of the disposable guard tube shown in Figs. 3A along its longitudinal axis with the frit coupled inside the bottom of the disposable guard tube, all according to some embodiments of the present invention.

Figure 4 includes Figs. 4A, 4B and 4C, where Fig. 4A shows a side view of a main combustion tube having a disposable guard tube arranged thereon with a frit coupled inside the bottom of the disposable guard tube, where Fig. 4B shows an exploded view of that shown in Fig. 4A with the main combustion tube and the disposable guard tube coupled together and the frit de-coupled from inside the bottom of the disposable guard tube, and Fig. 4C shows a bottom view of the disposable guard tube shown in Figs. 4A along its longitudinal axis with the frit coupled inside the bottom of the disposable guard tube, all according to some embodiments of the present invention.

Figure 5 includes Figs. 5A, 5B, 5C and 5D, where Fig. 5A shows a

perspective view of a disposable guard tube having a bottom portion with holes configured or formed therein next to its bottom, where Fig. 5B shows a side view of the disposable guard tube shown in Fig. 5A having the bottom portion with the holes configured or formed therein next to its bottom, and where Fig. 5C shows a bottom view of the disposable guard tube shown in Figs. 5A along its longitudinal axis thru its bottom, all according to some embodiments of the present invention.

Figure 6 shows a side view of a disposable guard tube having the bottom portion with slits configured or formed therein next to its bottom, all according to some embodiments of the present invention.

To reduce clutter in the drawing, each Figure in the drawing does not necessarily include every reference label for every element shown therein.

DETAILED DESCRIPTION OF BEST MODE OF THE INVENTION

By way of example, and consistent with that shown in Figures 1 -6, the present invention may include, or take the form of, a furnace system generally indicated as 10 (e.g., see Fig. 1 ), featuring a combination of a furnace 20 (Fig. 1 ), a main combustion furnace tube 30 (e.g., see Figs. 1 and 2) and a disposable guard tube 40, 40', 40", 40"' (e.g., see Figs. 1 -6). By way of example, the furnace system 10 may include, or form part of, a total organic carbon (TOC) system, e.g., for measuring organic contaminants in a water system.

Figures 1 -2

The main combustion furnace tube 30 may be configured to couple and extend from the furnace 20, may be made of a quartz tube material, and may have a zone 32 for a combustion catalyst or high temperature support configured or formed therein (e.g. like quartz chips). Main combustion furnace tubes like element 30 are known in the art, and the scope of the invention is not intended to be limited to any particular type or kind thereof, e.g., either now known or later developed in the future..

The disposable guard tube 40, 40', 40", 40"' may be coupled to the main combustion furnace tube 30, have a top 42 with a top opening 42a configured to receive and have direct exposure to a liquid sample (not shown) being injected, poured or provided into the main combustion furnace tube 30, and also have a bottom or bottom portion 44 with a bottom opening 44a to provide the liquid sample from the disposable guard tube 40, 40', 40", 40"' to the main combustion furnace tube 30 for processing in the zone 32 for the combustion catalyst or high

temperature support. By way of example, the most basic and preferred version of the disposable guard tube 40 according to present invention is a plain cylinder with top and bottom openings 42a, 44a on each end; however, the bottom 44 of the disposable guard tube 40', 40" can be fritted (see Figs. 3-4), or a bottom portion of the disposable guard tube 40", 40"' can be closed ended with holes or slits for gas flow (see Fig. 5-6). In effect, the disposable guard tube 40, 40', 40" is an

inexpensive disposable part that helps preserve the expensive main combustion furnace tube 30 extending its useful life.

The furnace 20 is configured to heat the liquid sample, e.g., in zones like element 32, for measuring and analyzing the organic contaminants in the water system. As one skilled in the art would appreciate, furnaces like element 20 for heating samples, including furnaces used in TOC systems are known in the art, and the scope of the invention is not intended to be limited to any particular type or kind thereof, e.g., either now known or later developed in the future. Figures 3-4: The Disposable Guard Tune 40' having Frit 46 Figures 3-4 show embodiments of the present invention with the main combustion tube 30 having a disposable guard tube 40' arranged thereon with a porous frit 46 coupled inside the bottom 44 of the disposable guard tube 40'. In Figure 3, the bottom portion 44 may be configured or formed to receive or accept the frit 46, e.g., by fusing an inside surface 44b of the bottom opening 44a and an outside surface 46a of the frit 46 in multiple places, e.g., including in at least 4 places. As one skilled in the art would appreciate, 100% fusing is not necessary to achieve the desired fusing to implement the present invention.

By way of example, the disposable guard tube 40' may be a cylindrical tubelike structure made of quartz (or a quartz-like material), and the frit 46 may also be a corresponding cylindrical structure also made of quartz (or a quartz-like material) as well. Techniques for fusing two structures together, e.g., such as quartz structures, are known in the art; and the scope of the invention is not intended to be limited to any particular type or kind of fusing technique, e.g., either now known or later developed in the future.

By way of example, the disposable guard tube 40' may be configured with suitable dimensions for coupling to an end of the combustion tube 30, e.g., like that shown in Figure 2. By way of one particular example, e.g., for one particular application, the dimensions of the disposable guard tube like element 40' may include an 18mm inner diameter (ID) x 20mm outer diameter (OD). (See the longitudinal dashed lines Figs 3A, 3B and 4A, 4B showing the

dimension/representation associated with the wall of the disposable guard tube 40'.) By way of one particular example, e.g., for one particular application, the dimensions may include a length of either 2.76 +/- 0.10 (Fig. 3), or 1 .50 +/- 0.10 (Fig. 4), e.g., including length dimensions measured in centimeters. Depending on the particular application, embodiments having different dimensions may be used in different embodiments/configurations/applications within the spirit of the present invention. Figure 5: Disposable guard tube 40" having holes

Figure 5 shows a disposable guard tube 40" having the bottom portion 44 with holes, some of which are labeled 48a, 48b, 48c, 48d, 48e, 48f, configured or formed therein for gas flow. The scope of the invention is not intended to be limited to the number of holes, the size/dimension of the holes, the geometric configuration of the holes, the arrangement/configuration (e.g., alternating up/down, circumferential and/or equidistant, etc.) of the holes, etc.; and embodiments are envisioned using other types or kind of of numbers, dimensions, configurations, arrangements, etc. of holes than that disclosed herein within the spirit of the present invention. Figure 6: Disposable guard tube 40"' having slits

Figure 6 shows a disposable guard tube 40"' having the bottom portion 44 slits, some of which are labeled 49a, 49b, 49c, configured or formed therein for gas flow. The scope of the invention is not intended to be limited to the number of slits, the size/dimension of the slits, the geometric configuration of the slits, the

arrangement/configuration (e.g., alternating up/down, circumferential and/or equidistant, etc.) of the slits, etc.; and embodiments are envisioned using other types or kind of of numbers, dimensions, configurations, arrangements, etc. of slits than that disclosed herein within the spirit of the present invention. Alternate Materials

The scope of the invention is intended to include, and embodiments are envisioned using, e.g., alternate materials that could also be used in place of quartz. By way of example, the alternate materials may include high temperature ceramics that could also be used in place of quartz, e.g. thin wall alumina (ranging from mullites to sapphire), titania, or any other material that is stable in a wet oxygen environment at greater than 1000 C. The ceramic carbides, ceramic nitrides, and ceramic borides may also work, but would have to be evaluated for stability and background interferences.

The Scope of the Invention

While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, may modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed herein as the best mode contemplated for carrying out this invention.