CA1213715A - Apparatus for and method of removing volatile boiler- feed additives from pressurized steam - Google Patents
Apparatus for and method of removing volatile boiler- feed additives from pressurized steamInfo
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- CA1213715A CA1213715A CA000406621A CA406621A CA1213715A CA 1213715 A CA1213715 A CA 1213715A CA 000406621 A CA000406621 A CA 000406621A CA 406621 A CA406621 A CA 406621A CA 1213715 A CA1213715 A CA 1213715A
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Abstract
ABSTRACT OF THE DISCLOSURE
An apparatus for and a method of removal of particulate material and boiler-feed additives from pressurized, saturated steam, which apparatus includes a composite cartridge in which particulate matter is removed by a filter tube and boiler-feed additives are removed by contacting the filtered steam with a bed of a hydrogen-form, strong-acid, ion-exchange resin, and sa-turated, pressurized steam substantially free of particulate matter and volatile, alkaline, boiler-feed additives are recovered for use, for example, in food-preparation and sterilization purposes.
An apparatus for and a method of removal of particulate material and boiler-feed additives from pressurized, saturated steam, which apparatus includes a composite cartridge in which particulate matter is removed by a filter tube and boiler-feed additives are removed by contacting the filtered steam with a bed of a hydrogen-form, strong-acid, ion-exchange resin, and sa-turated, pressurized steam substantially free of particulate matter and volatile, alkaline, boiler-feed additives are recovered for use, for example, in food-preparation and sterilization purposes.
Description
~*~
Pressurized~ saturated steam, particularly centrally generated steam, can be used for many purposes, such as for air humidification, food pre-paration and for the ste~ilization of medical devices. The use of pressurized steam, particularly in hospital sterilizers, has given rise to problems, such as stained and spotted sterilized instruments, dirty sterilizers requiring frequent cleaning, malfunctioning of steam-controlled valves, and an excess of maintenance on sterilizer door seals and gaskets. A frequent cause of problems in hospital sterilizers in particular is poor-quality steam; that is, a pres-surized, saturated steam that contains particulate matter, such as dirt from the piping system, pipe-scale rust, particles of packings and grease and oil, as well as liquid or condensed water carrying a wide range of contaminants therewith, such as boiler-feed additives, soluble salts and other organic mater-ial present in the boiler or water supply, and in addition includes other impurities, such as volatile boiler-feedwater additives, typically volatile alkaline additives, such as amines.
The problems associated with the use of steam, particularly in sterilizers, that is, caused by dirty steam, are often controlled or eliminated by filtering out the solid particulate material and the condensed water or other liquids out of the saturated steam, before the steam enters the sterilizer or is otherwise put to use. Usually, a steam filter is employed, which is an extremely efficient solids filter having a rating of 1 micron or better. Filter tubes composed of a plurality of nonwoven, randomly disposed borosilicate-glass fibers, having a bonding agent at the fiber-crossover points to form a porous, self-supporting filter tube, have been employed within a filter housing, to provide for a filtered, saturated steam.
The filter tube also contains a bonding agent, such as a silicone resin or fluorocarbon resin, which may be used at the steam temperatures. The ~2~ 37:1~
filter tube, for example, is placed within a housing within a cylindrical baf-fle. Unfiltered, saturated, pressurized steam enters the housing through an inlet port and is deflected around the centrifugal baffle, so that the change in direction causes much of the suspended water to drop to the bottom of the housing, from which it is removed automatically by a float-operated drain. The steam is essentially ree o condensed water and passes through the walls of the filter tube from the outside inwardly, and filtered steam is removed from the inside of the filter tube through an outlet port and into the sterilizer for use. It has been found that an efficient filter tube can remove virtually all or a substantial portion of the particulate and nonvo]atile, water-soluble impurities in saturated steam. However, it is desirable to provide an apparatus and a method for a very highly sterilized steam, particularly for use in hospital sterilizars.
~y invention relates to an apparatus for and a method of preparing highly purified steam essentially free of contaminants and volatile boiler-feed additives. In particular, my apparatus comprises a composite-cartridge filter and a method for removing volatile alkaline amines employed as boiler-feed additlves from filtered, pressurized steam.
I~ have discovered a method of preparing purified steam from steam which contains ~articulate matter and boiler-eed additives therein, which method comprises ~lltering the particulate and nonvolatile matter from a pres-surized, saturated steam by passing the steam through a ilter tube, which filter tube comprises a plurality of randomly disposed, nonwoven, inorganic fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from about 0.1 ~o 10 microns, and bonded at the junction o~ the fiber-crossover points with a bonding agent, to form a ~orous, self-supporting filter tube, recovering filtered steam from said filter tube, passing the filtered steam through a bed of a hydrogen-form, strong-acid, ion-exchange, high-temperature, resin material, to provide for the react:ion of the strong acid of the ion-exchange resin with volatile, alkaline, boiler-feed additives in the steam in an acid-base reaction, and recovering for use a purified, filtered, pressurized steam substantially free of alkaline, boiler-feed additives~
In a particular aspect, my invention provides a method of preparing purified, saturated, pressurized steam from pressurized, saturated steam which contains particulate matter and a volatile alkaline boiler-feed additive therein, which method comprises:
(a) passing the saturated, pressurized steam through the wall oE a filter tube, which filter tube comprises a plurality of randomly disposed, nonwoven, inorganic glass fibers having interstices therebetween, to define the porosity of the fi.lter tube, the fibers having a diameter of Erom 0.01 to lO microns, and bonded at the junction of the fiber~crossover points with a bonding agent to form a porous, self-supporting filter tube to filter the particulate matter from the pressurized saturated steam;
(bJ passing the particulate-free, filtered, pressurized saturated steam downstream through a bed of strong acid hydrogen-form ion-exchange resin material, the resin material composed of a high temperature, steam-resistant polymer, the resin material having a sufficient bed-depth to provide for the reaction of the strong acid hydrogen of the ion-exchange resin with the alkaline, volatile boiler-feed additive in the steam in an acid-base reaction, the saturated steam having a pressure of from 15 to 90 psi; and, (c) recovering a filtered, purified, saturated, pressurized steam essentially free of particulate matter and yolatile, alkaline, boiler-feed additive therein.
My invention also comprises a composi-te cartridge for the filtering and removing of particulate matter and boiler-feed additives, particularly volatile, alkaline, boiler-feed additives, such as amines, from saturated, pressurized steam, employing a composite cartriclge which contains a filter tube to remove solid, nonvolatile, water-soluble impurities from the steam, and which contains a bed of hydrogen-form, strong-acid, ion-exchange resin material downstream of the filter tube, to remove the volatile, alkaline, boiler-feed or other alkaline materials :Erom the steam -thereby providing for a pressurized, highly purified s-team, particularly suitable for use in food preparation and in hospital sterilizers.
In a particular aspect, my invention provides a composite cartridge for the filtering and removing of particulate matter and boiler-feed additives in saturated, pressurized steam, which cartridge comprises in combination: (a) a porous, self-supporting filter tube which comprises a plurality of randomly disposed, nonwoven, inorganic fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns and bonded at the junction of the fiber-crossover points with a bonding agent, to form a porous, self-supporting filter tube; (b) a bed of particulate, hydrogen-formt strong-acid, ion-exchange resin material peripherally adjacent at least one wall of the filter tube; and (c) porous retaining means to retain the ion-exchange resin adjacent the wall of the filter tube, whereby saturated steam is passed through - 3a -,3~71~
the wall of the filter tube and the bed of ion-exchange resin, to provide for a saturated steam with reduced particulate and boiler-feed additive contents.
In a further aspect, my invention provides a steam-st~rilizer system which comprises in combination: (a) a pressure vessel having an inlet to receive and introduce into the interior of the vessel highly purified, filtered, pressurized steam and an outlet to discharge air and steam condensate; (b) a composite-cartridge housing having an inlet to receive saturated, pressurized steam, containing particulate matter and boi]er-feed additives to be removed, and having an outlet to discharge highly purified filtered pressurized steam to and for use in the pressure vessel, the hous-ing containing downstream of the housing inlet (i) a porous, self-supporting filter tube which comprises a plurality of randomly di.sposed, nonwoven, inorganic fibers having interstices therebetween to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns and bonded at the junction of the fiber-crossover points with a bonding agen-t, to form a porous, self-suppor-ting filter tube to filter the saturated steam, (ii) a bed of strong-acid-form, ion-exchange resin material to react with the volatile, alkaline, boiler-feed additives in the fil-tered steam, and to provide a highly purified, filtered, pressurized steam to the housing outlet, and ~iii) a drain in the housing for the discharge of water containing nonvolatile, boiler-feed additive materials.
A wide variety of boiler-water additives is employed for various purposes, and in particular volatile, alkaline, boiler-feed additives are employed in boiler feedwater to control the - 3b -pH of the cQndensate to minimize corrosion in the steam-distribution system and boiler system. Typlcal volatile amlne addltlyes whlch may be employed lnclude, but are not llmlted to:
cyclohexyl amine; dlethylamlno ethanol; hydrazlne; morphollne, octadecyl amlne; or comblnatlons thereof. These volatlle, boiler-feed addltlves have been found to be present ln flltered steam.
The solid, particulate impurities in the steam are and can be removed by the employment of a ~lass-fiber filter tube, whlle the nonvolatile additives used as boller-feed ~ddltlves are typically carried into the steam llne in the entralned water and remain dissolved or suspended -- 3c -~2~'7~S
in the water. Therefore, a filter which effectively separates the condensate from the steam, before the steam enters the sterili7er usedJ will remove essen-tially or substantially all of the nonvolatile, feedwater additives.
~ lowever and importantly, it has been found that the volatile, boiler-feedwater additives are not removed, either in the condensed water or through the employment of a glass-fiber filter tube, alone. It has been dis-covered that an eficient, glass-fiber steam filter can remove virtually all of the solid impurities and the nonvolatile, water-soluble impurities from the steam, however, the glass-fiber filter tube has been found to remove only a small amount, if an~, Oe the volatile amine additives present in the steam. The major portion of these volatile amines remains in the vapor phase in the steam and enters the sterilizer and contacts the contents with the filtered steam.
Thus, the volatile amines present in the filtered steam may be de-posited on food during blanching or steam-cooking or on medical supplies, such as instruments or gauze~ during sterilization. Steam containing such amines is also often used with a conditioned air supply, and the air is sometimes humidiied by centrally generated steam, and, therefore, there is a possibility that such amine-contaminated steam may reach clean-rooms or critical areas of hosp~tals, including operating rooms, delivery rooms, recovery rooms and in-2Q tensive-care units. A further concern is that some of the amines, such as morpholine, present in the steal~ may react with nitrites or other foodstuff additives, to form nitrosoamines or other compounds which may be or are poten-tial animal carcinogens.
It has been ~ound that volatile, alkaline materials, such as the volatile amines used as boiler-feed additives, may be removed effectively from ~iltered steam through the employment, directly downstream or adjacent to the filtering operation, qf an ion-exchange resin in a strong-acid form. The ion-~. ~ .., 3'7~
exchange resin, particularly in particulate form, should be com-posed of a high-temperature or steam-resis-tant polymer, such as styrene copolymers of the like, which is susceptible to use with with steam, without degradation or substantial deterioration. The employment of the ion-exchange resin material removes the amine vapors present in the filtered steam, by the formation of a resin salt in a reaction analogous to an acicl-base reaction. Thus, where a sulfonic-acid-type ion-exchange resin is employed, the volatile amines, such as morpholine and the like, react in an acid-base reaction, to form the resin salt of the polymer and water. Usually, pressurized steam is employed at a range of from about 15 to 90 psi in hospitals, and, therefore, the upper temper-ature limit of the ion-exchange resin to he employed in my inven-tion is about 300F or higher, if possible, which would permit the steam to be purified, employing the ion-exchange resin at a pressure up to about 65 psi.
The ion-exchange resin employed should be of the strong-acid type, particularly in the hydrogen form, and not the sodium or potassium form, because it is desired to effect an acid-base reaction with the volatile, alkaline material in the pressurized steam. The use of boiler-feedwater additives used in the prepar-ation of steam that will contact food has been recognized by the FDA, and upper limits have been set for particular, common ad-ditives, set forth in the Federal Register, Section 173,310(d), entitled "Boiler Water Additives".
In my method and apparatus, the filtered steam is directed to and passes through a bed of ion-exchange resin of sufficient depth, to permit the reaction of all or essentially 3~
all of the volatile amines in an acid-base reaction with the strong acid on the ion-exchange resin, so that the pressurized steam recovered, after passing through the bed, is essentially free of a volatile, alkaline material or contains only very minor traces of such materials;
- 5a -7~
for example, less than 3 ppm. The ion-exchange resin is typically in bead or other particulate form, and may be placed in a separate contai]ler and spaced apart from, and downstream of, the steam filter tube, but more desirably is directly adjacent the filter tube, so that filtration and neutralization of the steam occur withi.n a single, composite cartridge, as more particularly will be described hereater. Such cartridge is normally employed in a housing, to permit the change in direction of the steam and the removal of condensed water from the housing drain, with the pressurized s~eam then passing through the walls of the filter tube and, thereafter, through the bed of strong-acid, ion-exchange resin.
In one embodiment, a strong-acid, ion-exchange resin is placed in-Between two glass-fiber ~ilter tubes or one upstream filter tube and a down-stream, porous, tubular retainer or support, whereby the satur~ted steam is passed through one wall of the filter tube, is neutralized by passing through the ion-exchange bed and is further filtered or passed through the wall of the Eilter tube or retainer on the opposite side of the bed. ~or example, the filter tube may be arranged concentrically, with the inside of the inside fil-ter tube supported by a perforated core, with the flow of the steam being from the outside to the inside, and the purified steam is removed from the inside of the concentric filter tube, which combination forms a composite cartridge.
~n another embodiment, the ion-exchange resin may be placed directly adjacent a filter tube or a series of filter tubes in a solid-bed form; for example, directly downstream of the filtered steam, so that the saturated steam, containing the impurities, is filtered by passing it through the walls of a glass-fiber filter tube, and, thereafter, passes through a solid particulate Bed of ion-exchange resin directly downstream of the ilter tube; for example, where the bed is axially aligned therewith, and the filtered, highly purified, ~ 6 -~3~7~
neutralized steam is removed from the solid, ion-exchange bed.
The filter tubes suitable for use include those filter ~ubes which are composed of a plurality of inorganic fibers, such as glass and typically borosilicate glass fibers or alumina or zirconia fibers, randomly disposed to form a porous, sel~-supporting filter tube, with the diameter of the fibers ranging from about 0.01 to 10 microns; for example, 0.03 to 8 microns, and typically 0.1 to 4 microns, the fibers arranged so that the interstices between the fibers deine the porosity of the filter tube, and with the crossover points o:E the fibers in the filter tube containing a bonding agent, such as a hardened material, and typically a hardened res.in material, such as a silicone or fluoro-carbon resin, which bonding material would be impervious or not degraded by the steam in use. ~ typical glass-fiber filter tube, employing a fluorocarbon bonding agent, suitable for use in the invention and in the composite cartridge, which is deined herein, is set forth in United States Patent 4,210,540, issued July 1, 1980.
The invention will now be described in greater detail with reference to the accompanying drawings, in which:
~igure l is an illustrative system or the furnishing of filtered, highly puriied steam to a sterllizerJ employing a composite cartridge of the 2a invention;
~gure 2 is an illustrative, cross-sectional view of a composite cartridge of the invention; and Pigure 3 is an illustrative view of another composite cartridge of the invention.
p~gure 1 illustrates a system for the suppl~ o highly purified pressurized steam, which system 10 comprises a pressure vessel 12, such as a h~spital sterllizer, a housing 36 for a composite cartridge filter 38, which ~3~S
housing includes a drain 26J such as an automatic drain. The housing is secured to a pressurized, saturai::ed-steam inlet line 14 and an outlet line 16, with three-wa~ valves 18 and 20 in the respective lines7 and having a bypass line 22, with the outlet line includin~ a pressure gauge 28. The pressure vessel 12 includes therein sterilized, filtered, pressurized steam 24, and the vessel includes a vessel outlet line 34 including a pressure gauge 30 which contains a trap 32 which passes an air-and-steam mixture and retains pure steam, which trap discharges air to the atmosphere.
In operation, a pressurized, saturated steam is introduced to in-let 14 and into the housing 36, and exterior of the outer wall of the composite cartridge 38, a cylindrical baffle (not shown~ exterior o-f and spaced apart from the cartridge is optional, the steam passing through the cartridge 38 and out the outlet through valve 18 and line 16 into the pressurized vessel 12 as highly purified, pressurized steam 24. The automatic drain 26 discharges water, containing nonvolatile, boiler additives, from the saturated steam from the housing. Condensed water is passed through the trap 32.
Pigure 2 is a cross-sectional, illustrative embodiment of a com-posite cartridge use~ul in the system 10 of ~igure 1, which composite cartridge 38 includes $itted or sealed end caps 40 and 42, an outer filter tube 44 compos-ed of borosilicate-glass-fibers, with a silicone or fluorocarbon resin-bonding agent, and another internal, borosilicate-glass~fiber, inner filter tube 46 which may~be the same or different from the filter tube 44, and contained within the filter tubes 44 and 46 is a bed 48 of a sulfonic-acid, ion-exchange resin i~n particulate or bead form. A stainless-steel mesh or other porous support core 50 is employed. The end cap 42 includes an outlet for steam, and end cap 40 closes off the bottom of the support core. The flow of the steam is schemati-cally illustrated by the flow arrows.
~2:~3'7~S
In operation, saturated steam passes through the wall of the ilter tube 44 through resin bed 4~ and through the wall of filter tube ~6 and into the interior passageway, and is discharged out outlet 52 as highly purified filtered9 pressurized steam ready for use in a hospital sterilizer.
~ igure 3 i5 an illustrative, sectional view of another composite cartridge of the inventionJ which includes end caps 54 and 56, with end cap 56 having a steam outlet 66, and with end cap 54 being imperforate. A glass-fiber filter tube 58 is employed in the lower portion of the cartridge, while a bed of ion-exchange res m beads 60 is formed directly above the axial line as part of the composite cartridge. An open-mesh, porous, support grid 62, such as of stainless steel, separates and retains the ion-exchange resin from the interior of the filter tube 58. The ion-exchange resin is retained in a tubular, non-porous, plastic, sleeve element 64.
In operation, pressurized, saturated steam passes through the walls of the filter 58 at the lower portion of the composite cartridge which is in the housing, and then passes upwardly through the center of the filter tube to the porous, support, open-mesh material 62 and through the tubular bed of par-ticulate, acid, ion-exchange resin 60, and the highly sterilized, filtered, pres-surized steam is then discharged from the top outlet 66.
E~am~le _ 195 grams of Amberlite ~a registered trademark of Rohm ~ Haas Co.~
200 CH, strong-acid, lon-exchange resin were filled into the annular space be-tween two hardened resin bonded glass-fiber filter tubes of 0.75" in diameter and 2.001' in diameter. End caps were then potted on and the entire cartridge was installed in a steam-filter housing. The housing had been installed pre-viously in a steam_distribution systemJ with a working pressure of 10 to 15 psig s*eam. ~orpholine was then added to the boiler, feeding the sys~em in an amount = ~
~Z~L3~1~
sufficient to generate 3 ppm by weight in the steam condensate. Samples of the steam condensate were taken upstream and downstream of the housing, by bleeding steam through a copper coil cooled with water. ~lass collection bottles, which had been rinsed previously with distilled water, were used to collect the condensate. Using a Taylor Water Analyzer Klt No. 1300, the concentration of morpholine in ppm by weight was determined. rn the test used, morph~line reacts wlth carbon disulfide to orm a thiocarbamate compound. This carbonate reacts with excess copper ion to form a brown-colored compound, wlth the inten-sity of the brown color being proportioned to the concentration of morpholine present.
The results were as ollows;
Concentration upstream filter; 3.0 ppm Concentration downstream filter; 0.2 ppm Example 2.
After 2~ hours had elapsed, the procedure ln Example 1 was repeated, and the results were as follows;
Concentration upstream ilter 2.0 ppm Concentration downstream fllter 0.2 ppm Example 3.
2Q E~ample 1 was repeated, but the ion-exchange filter cartridge was removed from the system, with no other changes. The results were as follows:
Concentratlon upstream 1.5 ppm Concentration downstream 1.5 ppm Example 4.
Boiler-eedwater additives fall generally into the following cate-gories: binding agents or calcium, magnesium and silicon, to prevent solids from plating out on the hot tube walls ~examples of these materials are sodium - lQ -L3 ~
tripolyphosphate, sodium alglnate and tetrasodium EDTA ~a chelating agent));
oxygen scavengers to retard tube corrosion, which can bc accelerated by dissolv-ed oxygen in the feedwater ~examples are sodium sulfite and hydrazine); and alkaline bu$~ers to keep the p~ of the feedwater in the desired range; for example, 6.5 to 8.5.
In practice, steam condensate is encountered at p~l 9 or even higher.
Sodium carbonate, sodium aluminate, morpholine and cyclohexyl amine are some materials used as alkaline buffers. The latter two products have the advantage of being volatile, and, therefore, they can protect the entire steam-distribution system and condensate return lines from acidic corrosion.
~urther boiler-feedwater additives are volatile corrosion inhibitors which form a protective film on pipes or other metal surfaces. Octadecyl amine, a long-chain fatty amine, is typically added to boiler_feedwater for this purpose.
Nonvolatile additives constitute the great bulk of the boiler-feed-water additives. The nonvolatile additives are carried into the steam line in the entrained water, and they remain dissolved or suspended in the water.
Therefore, a filter which e$fectively separates condensate from steam, before the steam enters the sterilizer, will remove essentially all of the nonvolatile 2Q feedwater additives.
To obtain quantitative information on concentrations of volatile amines in the steam to hospital sterilizers, analytical determinations on the steamsystem of a hospital, which uses morpholine as one of its boiler-feedwater additives, were made. The testing was done at a sterilizer which has a filter housing containing a fluorocarbon resin bonded glass-fiber filter tube on the steam line. Tests were made on six days over about a one-month period. Each result is the average of two or three determinations. Steam was sampled both ~!L21~71~
upstream and downstream of the filter tube, which is located immediately up-stream of the sterilizer steam inlet. The concentration of morpholine inside the sterilizer was the s~le as the concentration downstream of the filter. The concentration of morpholine in the boiler feedwater, itself, was also deter-mined. The test results are:
~orpholine Concentration, ppm Date B~iler UpstreamDownstream Days Peedwater of filterof Filter -November 19 - 2.6 1.8 November 20 - 2.9 2.0 November 24 4.0 4.0 3.2 December 1 - 5-5 4.0 December 19 - 4.2 3.6 December 22 - 3.5 2.5 On the average, the ilter tube reduced the morpholine concentration in the steam by about 25%, presumably by removing the liquid water in which some of the morpholine is dissolved. ~lowever, the major portion of the morpholine re-mained in the vapor phase and entered the sterilizer with the filtered steam.
Thus, while an eficient, steam, glass-fiber ilter tube can remove virtually all solid impurities and nonvolatile water-soluble impurities from the steam, the ilter will remove only about one-fourth of the volatile amines in the steam, while, as demonstrated, the employment of a bed of strong-acid ion-exchange resin immediately downstream of the filter removes the volatile, alkaline additives from the iltered steam.
Pressurized~ saturated steam, particularly centrally generated steam, can be used for many purposes, such as for air humidification, food pre-paration and for the ste~ilization of medical devices. The use of pressurized steam, particularly in hospital sterilizers, has given rise to problems, such as stained and spotted sterilized instruments, dirty sterilizers requiring frequent cleaning, malfunctioning of steam-controlled valves, and an excess of maintenance on sterilizer door seals and gaskets. A frequent cause of problems in hospital sterilizers in particular is poor-quality steam; that is, a pres-surized, saturated steam that contains particulate matter, such as dirt from the piping system, pipe-scale rust, particles of packings and grease and oil, as well as liquid or condensed water carrying a wide range of contaminants therewith, such as boiler-feed additives, soluble salts and other organic mater-ial present in the boiler or water supply, and in addition includes other impurities, such as volatile boiler-feedwater additives, typically volatile alkaline additives, such as amines.
The problems associated with the use of steam, particularly in sterilizers, that is, caused by dirty steam, are often controlled or eliminated by filtering out the solid particulate material and the condensed water or other liquids out of the saturated steam, before the steam enters the sterilizer or is otherwise put to use. Usually, a steam filter is employed, which is an extremely efficient solids filter having a rating of 1 micron or better. Filter tubes composed of a plurality of nonwoven, randomly disposed borosilicate-glass fibers, having a bonding agent at the fiber-crossover points to form a porous, self-supporting filter tube, have been employed within a filter housing, to provide for a filtered, saturated steam.
The filter tube also contains a bonding agent, such as a silicone resin or fluorocarbon resin, which may be used at the steam temperatures. The ~2~ 37:1~
filter tube, for example, is placed within a housing within a cylindrical baf-fle. Unfiltered, saturated, pressurized steam enters the housing through an inlet port and is deflected around the centrifugal baffle, so that the change in direction causes much of the suspended water to drop to the bottom of the housing, from which it is removed automatically by a float-operated drain. The steam is essentially ree o condensed water and passes through the walls of the filter tube from the outside inwardly, and filtered steam is removed from the inside of the filter tube through an outlet port and into the sterilizer for use. It has been found that an efficient filter tube can remove virtually all or a substantial portion of the particulate and nonvo]atile, water-soluble impurities in saturated steam. However, it is desirable to provide an apparatus and a method for a very highly sterilized steam, particularly for use in hospital sterilizars.
~y invention relates to an apparatus for and a method of preparing highly purified steam essentially free of contaminants and volatile boiler-feed additives. In particular, my apparatus comprises a composite-cartridge filter and a method for removing volatile alkaline amines employed as boiler-feed additlves from filtered, pressurized steam.
I~ have discovered a method of preparing purified steam from steam which contains ~articulate matter and boiler-eed additives therein, which method comprises ~lltering the particulate and nonvolatile matter from a pres-surized, saturated steam by passing the steam through a ilter tube, which filter tube comprises a plurality of randomly disposed, nonwoven, inorganic fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from about 0.1 ~o 10 microns, and bonded at the junction o~ the fiber-crossover points with a bonding agent, to form a ~orous, self-supporting filter tube, recovering filtered steam from said filter tube, passing the filtered steam through a bed of a hydrogen-form, strong-acid, ion-exchange, high-temperature, resin material, to provide for the react:ion of the strong acid of the ion-exchange resin with volatile, alkaline, boiler-feed additives in the steam in an acid-base reaction, and recovering for use a purified, filtered, pressurized steam substantially free of alkaline, boiler-feed additives~
In a particular aspect, my invention provides a method of preparing purified, saturated, pressurized steam from pressurized, saturated steam which contains particulate matter and a volatile alkaline boiler-feed additive therein, which method comprises:
(a) passing the saturated, pressurized steam through the wall oE a filter tube, which filter tube comprises a plurality of randomly disposed, nonwoven, inorganic glass fibers having interstices therebetween, to define the porosity of the fi.lter tube, the fibers having a diameter of Erom 0.01 to lO microns, and bonded at the junction of the fiber~crossover points with a bonding agent to form a porous, self-supporting filter tube to filter the particulate matter from the pressurized saturated steam;
(bJ passing the particulate-free, filtered, pressurized saturated steam downstream through a bed of strong acid hydrogen-form ion-exchange resin material, the resin material composed of a high temperature, steam-resistant polymer, the resin material having a sufficient bed-depth to provide for the reaction of the strong acid hydrogen of the ion-exchange resin with the alkaline, volatile boiler-feed additive in the steam in an acid-base reaction, the saturated steam having a pressure of from 15 to 90 psi; and, (c) recovering a filtered, purified, saturated, pressurized steam essentially free of particulate matter and yolatile, alkaline, boiler-feed additive therein.
My invention also comprises a composi-te cartridge for the filtering and removing of particulate matter and boiler-feed additives, particularly volatile, alkaline, boiler-feed additives, such as amines, from saturated, pressurized steam, employing a composite cartriclge which contains a filter tube to remove solid, nonvolatile, water-soluble impurities from the steam, and which contains a bed of hydrogen-form, strong-acid, ion-exchange resin material downstream of the filter tube, to remove the volatile, alkaline, boiler-feed or other alkaline materials :Erom the steam -thereby providing for a pressurized, highly purified s-team, particularly suitable for use in food preparation and in hospital sterilizers.
In a particular aspect, my invention provides a composite cartridge for the filtering and removing of particulate matter and boiler-feed additives in saturated, pressurized steam, which cartridge comprises in combination: (a) a porous, self-supporting filter tube which comprises a plurality of randomly disposed, nonwoven, inorganic fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns and bonded at the junction of the fiber-crossover points with a bonding agent, to form a porous, self-supporting filter tube; (b) a bed of particulate, hydrogen-formt strong-acid, ion-exchange resin material peripherally adjacent at least one wall of the filter tube; and (c) porous retaining means to retain the ion-exchange resin adjacent the wall of the filter tube, whereby saturated steam is passed through - 3a -,3~71~
the wall of the filter tube and the bed of ion-exchange resin, to provide for a saturated steam with reduced particulate and boiler-feed additive contents.
In a further aspect, my invention provides a steam-st~rilizer system which comprises in combination: (a) a pressure vessel having an inlet to receive and introduce into the interior of the vessel highly purified, filtered, pressurized steam and an outlet to discharge air and steam condensate; (b) a composite-cartridge housing having an inlet to receive saturated, pressurized steam, containing particulate matter and boi]er-feed additives to be removed, and having an outlet to discharge highly purified filtered pressurized steam to and for use in the pressure vessel, the hous-ing containing downstream of the housing inlet (i) a porous, self-supporting filter tube which comprises a plurality of randomly di.sposed, nonwoven, inorganic fibers having interstices therebetween to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns and bonded at the junction of the fiber-crossover points with a bonding agen-t, to form a porous, self-suppor-ting filter tube to filter the saturated steam, (ii) a bed of strong-acid-form, ion-exchange resin material to react with the volatile, alkaline, boiler-feed additives in the fil-tered steam, and to provide a highly purified, filtered, pressurized steam to the housing outlet, and ~iii) a drain in the housing for the discharge of water containing nonvolatile, boiler-feed additive materials.
A wide variety of boiler-water additives is employed for various purposes, and in particular volatile, alkaline, boiler-feed additives are employed in boiler feedwater to control the - 3b -pH of the cQndensate to minimize corrosion in the steam-distribution system and boiler system. Typlcal volatile amlne addltlyes whlch may be employed lnclude, but are not llmlted to:
cyclohexyl amine; dlethylamlno ethanol; hydrazlne; morphollne, octadecyl amlne; or comblnatlons thereof. These volatlle, boiler-feed addltlves have been found to be present ln flltered steam.
The solid, particulate impurities in the steam are and can be removed by the employment of a ~lass-fiber filter tube, whlle the nonvolatile additives used as boller-feed ~ddltlves are typically carried into the steam llne in the entralned water and remain dissolved or suspended -- 3c -~2~'7~S
in the water. Therefore, a filter which effectively separates the condensate from the steam, before the steam enters the sterili7er usedJ will remove essen-tially or substantially all of the nonvolatile, feedwater additives.
~ lowever and importantly, it has been found that the volatile, boiler-feedwater additives are not removed, either in the condensed water or through the employment of a glass-fiber filter tube, alone. It has been dis-covered that an eficient, glass-fiber steam filter can remove virtually all of the solid impurities and the nonvolatile, water-soluble impurities from the steam, however, the glass-fiber filter tube has been found to remove only a small amount, if an~, Oe the volatile amine additives present in the steam. The major portion of these volatile amines remains in the vapor phase in the steam and enters the sterilizer and contacts the contents with the filtered steam.
Thus, the volatile amines present in the filtered steam may be de-posited on food during blanching or steam-cooking or on medical supplies, such as instruments or gauze~ during sterilization. Steam containing such amines is also often used with a conditioned air supply, and the air is sometimes humidiied by centrally generated steam, and, therefore, there is a possibility that such amine-contaminated steam may reach clean-rooms or critical areas of hosp~tals, including operating rooms, delivery rooms, recovery rooms and in-2Q tensive-care units. A further concern is that some of the amines, such as morpholine, present in the steal~ may react with nitrites or other foodstuff additives, to form nitrosoamines or other compounds which may be or are poten-tial animal carcinogens.
It has been ~ound that volatile, alkaline materials, such as the volatile amines used as boiler-feed additives, may be removed effectively from ~iltered steam through the employment, directly downstream or adjacent to the filtering operation, qf an ion-exchange resin in a strong-acid form. The ion-~. ~ .., 3'7~
exchange resin, particularly in particulate form, should be com-posed of a high-temperature or steam-resis-tant polymer, such as styrene copolymers of the like, which is susceptible to use with with steam, without degradation or substantial deterioration. The employment of the ion-exchange resin material removes the amine vapors present in the filtered steam, by the formation of a resin salt in a reaction analogous to an acicl-base reaction. Thus, where a sulfonic-acid-type ion-exchange resin is employed, the volatile amines, such as morpholine and the like, react in an acid-base reaction, to form the resin salt of the polymer and water. Usually, pressurized steam is employed at a range of from about 15 to 90 psi in hospitals, and, therefore, the upper temper-ature limit of the ion-exchange resin to he employed in my inven-tion is about 300F or higher, if possible, which would permit the steam to be purified, employing the ion-exchange resin at a pressure up to about 65 psi.
The ion-exchange resin employed should be of the strong-acid type, particularly in the hydrogen form, and not the sodium or potassium form, because it is desired to effect an acid-base reaction with the volatile, alkaline material in the pressurized steam. The use of boiler-feedwater additives used in the prepar-ation of steam that will contact food has been recognized by the FDA, and upper limits have been set for particular, common ad-ditives, set forth in the Federal Register, Section 173,310(d), entitled "Boiler Water Additives".
In my method and apparatus, the filtered steam is directed to and passes through a bed of ion-exchange resin of sufficient depth, to permit the reaction of all or essentially 3~
all of the volatile amines in an acid-base reaction with the strong acid on the ion-exchange resin, so that the pressurized steam recovered, after passing through the bed, is essentially free of a volatile, alkaline material or contains only very minor traces of such materials;
- 5a -7~
for example, less than 3 ppm. The ion-exchange resin is typically in bead or other particulate form, and may be placed in a separate contai]ler and spaced apart from, and downstream of, the steam filter tube, but more desirably is directly adjacent the filter tube, so that filtration and neutralization of the steam occur withi.n a single, composite cartridge, as more particularly will be described hereater. Such cartridge is normally employed in a housing, to permit the change in direction of the steam and the removal of condensed water from the housing drain, with the pressurized s~eam then passing through the walls of the filter tube and, thereafter, through the bed of strong-acid, ion-exchange resin.
In one embodiment, a strong-acid, ion-exchange resin is placed in-Between two glass-fiber ~ilter tubes or one upstream filter tube and a down-stream, porous, tubular retainer or support, whereby the satur~ted steam is passed through one wall of the filter tube, is neutralized by passing through the ion-exchange bed and is further filtered or passed through the wall of the Eilter tube or retainer on the opposite side of the bed. ~or example, the filter tube may be arranged concentrically, with the inside of the inside fil-ter tube supported by a perforated core, with the flow of the steam being from the outside to the inside, and the purified steam is removed from the inside of the concentric filter tube, which combination forms a composite cartridge.
~n another embodiment, the ion-exchange resin may be placed directly adjacent a filter tube or a series of filter tubes in a solid-bed form; for example, directly downstream of the filtered steam, so that the saturated steam, containing the impurities, is filtered by passing it through the walls of a glass-fiber filter tube, and, thereafter, passes through a solid particulate Bed of ion-exchange resin directly downstream of the ilter tube; for example, where the bed is axially aligned therewith, and the filtered, highly purified, ~ 6 -~3~7~
neutralized steam is removed from the solid, ion-exchange bed.
The filter tubes suitable for use include those filter ~ubes which are composed of a plurality of inorganic fibers, such as glass and typically borosilicate glass fibers or alumina or zirconia fibers, randomly disposed to form a porous, sel~-supporting filter tube, with the diameter of the fibers ranging from about 0.01 to 10 microns; for example, 0.03 to 8 microns, and typically 0.1 to 4 microns, the fibers arranged so that the interstices between the fibers deine the porosity of the filter tube, and with the crossover points o:E the fibers in the filter tube containing a bonding agent, such as a hardened material, and typically a hardened res.in material, such as a silicone or fluoro-carbon resin, which bonding material would be impervious or not degraded by the steam in use. ~ typical glass-fiber filter tube, employing a fluorocarbon bonding agent, suitable for use in the invention and in the composite cartridge, which is deined herein, is set forth in United States Patent 4,210,540, issued July 1, 1980.
The invention will now be described in greater detail with reference to the accompanying drawings, in which:
~igure l is an illustrative system or the furnishing of filtered, highly puriied steam to a sterllizerJ employing a composite cartridge of the 2a invention;
~gure 2 is an illustrative, cross-sectional view of a composite cartridge of the invention; and Pigure 3 is an illustrative view of another composite cartridge of the invention.
p~gure 1 illustrates a system for the suppl~ o highly purified pressurized steam, which system 10 comprises a pressure vessel 12, such as a h~spital sterllizer, a housing 36 for a composite cartridge filter 38, which ~3~S
housing includes a drain 26J such as an automatic drain. The housing is secured to a pressurized, saturai::ed-steam inlet line 14 and an outlet line 16, with three-wa~ valves 18 and 20 in the respective lines7 and having a bypass line 22, with the outlet line includin~ a pressure gauge 28. The pressure vessel 12 includes therein sterilized, filtered, pressurized steam 24, and the vessel includes a vessel outlet line 34 including a pressure gauge 30 which contains a trap 32 which passes an air-and-steam mixture and retains pure steam, which trap discharges air to the atmosphere.
In operation, a pressurized, saturated steam is introduced to in-let 14 and into the housing 36, and exterior of the outer wall of the composite cartridge 38, a cylindrical baffle (not shown~ exterior o-f and spaced apart from the cartridge is optional, the steam passing through the cartridge 38 and out the outlet through valve 18 and line 16 into the pressurized vessel 12 as highly purified, pressurized steam 24. The automatic drain 26 discharges water, containing nonvolatile, boiler additives, from the saturated steam from the housing. Condensed water is passed through the trap 32.
Pigure 2 is a cross-sectional, illustrative embodiment of a com-posite cartridge use~ul in the system 10 of ~igure 1, which composite cartridge 38 includes $itted or sealed end caps 40 and 42, an outer filter tube 44 compos-ed of borosilicate-glass-fibers, with a silicone or fluorocarbon resin-bonding agent, and another internal, borosilicate-glass~fiber, inner filter tube 46 which may~be the same or different from the filter tube 44, and contained within the filter tubes 44 and 46 is a bed 48 of a sulfonic-acid, ion-exchange resin i~n particulate or bead form. A stainless-steel mesh or other porous support core 50 is employed. The end cap 42 includes an outlet for steam, and end cap 40 closes off the bottom of the support core. The flow of the steam is schemati-cally illustrated by the flow arrows.
~2:~3'7~S
In operation, saturated steam passes through the wall of the ilter tube 44 through resin bed 4~ and through the wall of filter tube ~6 and into the interior passageway, and is discharged out outlet 52 as highly purified filtered9 pressurized steam ready for use in a hospital sterilizer.
~ igure 3 i5 an illustrative, sectional view of another composite cartridge of the inventionJ which includes end caps 54 and 56, with end cap 56 having a steam outlet 66, and with end cap 54 being imperforate. A glass-fiber filter tube 58 is employed in the lower portion of the cartridge, while a bed of ion-exchange res m beads 60 is formed directly above the axial line as part of the composite cartridge. An open-mesh, porous, support grid 62, such as of stainless steel, separates and retains the ion-exchange resin from the interior of the filter tube 58. The ion-exchange resin is retained in a tubular, non-porous, plastic, sleeve element 64.
In operation, pressurized, saturated steam passes through the walls of the filter 58 at the lower portion of the composite cartridge which is in the housing, and then passes upwardly through the center of the filter tube to the porous, support, open-mesh material 62 and through the tubular bed of par-ticulate, acid, ion-exchange resin 60, and the highly sterilized, filtered, pres-surized steam is then discharged from the top outlet 66.
E~am~le _ 195 grams of Amberlite ~a registered trademark of Rohm ~ Haas Co.~
200 CH, strong-acid, lon-exchange resin were filled into the annular space be-tween two hardened resin bonded glass-fiber filter tubes of 0.75" in diameter and 2.001' in diameter. End caps were then potted on and the entire cartridge was installed in a steam-filter housing. The housing had been installed pre-viously in a steam_distribution systemJ with a working pressure of 10 to 15 psig s*eam. ~orpholine was then added to the boiler, feeding the sys~em in an amount = ~
~Z~L3~1~
sufficient to generate 3 ppm by weight in the steam condensate. Samples of the steam condensate were taken upstream and downstream of the housing, by bleeding steam through a copper coil cooled with water. ~lass collection bottles, which had been rinsed previously with distilled water, were used to collect the condensate. Using a Taylor Water Analyzer Klt No. 1300, the concentration of morpholine in ppm by weight was determined. rn the test used, morph~line reacts wlth carbon disulfide to orm a thiocarbamate compound. This carbonate reacts with excess copper ion to form a brown-colored compound, wlth the inten-sity of the brown color being proportioned to the concentration of morpholine present.
The results were as ollows;
Concentration upstream filter; 3.0 ppm Concentration downstream filter; 0.2 ppm Example 2.
After 2~ hours had elapsed, the procedure ln Example 1 was repeated, and the results were as follows;
Concentration upstream ilter 2.0 ppm Concentration downstream fllter 0.2 ppm Example 3.
2Q E~ample 1 was repeated, but the ion-exchange filter cartridge was removed from the system, with no other changes. The results were as follows:
Concentratlon upstream 1.5 ppm Concentration downstream 1.5 ppm Example 4.
Boiler-eedwater additives fall generally into the following cate-gories: binding agents or calcium, magnesium and silicon, to prevent solids from plating out on the hot tube walls ~examples of these materials are sodium - lQ -L3 ~
tripolyphosphate, sodium alglnate and tetrasodium EDTA ~a chelating agent));
oxygen scavengers to retard tube corrosion, which can bc accelerated by dissolv-ed oxygen in the feedwater ~examples are sodium sulfite and hydrazine); and alkaline bu$~ers to keep the p~ of the feedwater in the desired range; for example, 6.5 to 8.5.
In practice, steam condensate is encountered at p~l 9 or even higher.
Sodium carbonate, sodium aluminate, morpholine and cyclohexyl amine are some materials used as alkaline buffers. The latter two products have the advantage of being volatile, and, therefore, they can protect the entire steam-distribution system and condensate return lines from acidic corrosion.
~urther boiler-feedwater additives are volatile corrosion inhibitors which form a protective film on pipes or other metal surfaces. Octadecyl amine, a long-chain fatty amine, is typically added to boiler_feedwater for this purpose.
Nonvolatile additives constitute the great bulk of the boiler-feed-water additives. The nonvolatile additives are carried into the steam line in the entrained water, and they remain dissolved or suspended in the water.
Therefore, a filter which e$fectively separates condensate from steam, before the steam enters the sterilizer, will remove essentially all of the nonvolatile 2Q feedwater additives.
To obtain quantitative information on concentrations of volatile amines in the steam to hospital sterilizers, analytical determinations on the steamsystem of a hospital, which uses morpholine as one of its boiler-feedwater additives, were made. The testing was done at a sterilizer which has a filter housing containing a fluorocarbon resin bonded glass-fiber filter tube on the steam line. Tests were made on six days over about a one-month period. Each result is the average of two or three determinations. Steam was sampled both ~!L21~71~
upstream and downstream of the filter tube, which is located immediately up-stream of the sterilizer steam inlet. The concentration of morpholine inside the sterilizer was the s~le as the concentration downstream of the filter. The concentration of morpholine in the boiler feedwater, itself, was also deter-mined. The test results are:
~orpholine Concentration, ppm Date B~iler UpstreamDownstream Days Peedwater of filterof Filter -November 19 - 2.6 1.8 November 20 - 2.9 2.0 November 24 4.0 4.0 3.2 December 1 - 5-5 4.0 December 19 - 4.2 3.6 December 22 - 3.5 2.5 On the average, the ilter tube reduced the morpholine concentration in the steam by about 25%, presumably by removing the liquid water in which some of the morpholine is dissolved. ~lowever, the major portion of the morpholine re-mained in the vapor phase and entered the sterilizer with the filtered steam.
Thus, while an eficient, steam, glass-fiber ilter tube can remove virtually all solid impurities and nonvolatile water-soluble impurities from the steam, the ilter will remove only about one-fourth of the volatile amines in the steam, while, as demonstrated, the employment of a bed of strong-acid ion-exchange resin immediately downstream of the filter removes the volatile, alkaline additives from the iltered steam.
Claims (28)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of preparing purified, saturated, pressurized steam from pressurized, saturated steam which contains particulate matter and a volatile, alkaline boiler-feed additive therein, which method comprises:
(a) passing the saturated, pressurized steam through the wall of a filter tube, which filter tube comprises a plurality of randomly disposed, nonwoven, inorganic glass fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns, and bonded at the junction of the fiber-crossover points with a bonding agent to form a porous, self-supporting filter tube to filter the particulate matter from the pressurized saturated steam;
(b) passing the particulate-free, filtered, pressurized saturated steam downstream through a bed of strong acid hydrogen-form ion-exchange resin material, the resin material composed of a high temperature, steam-resistant polymer, the resin material having a sufficient bed-depth to provide for the reaction of the strong acid hydrogen of the ion-exchange resin with the alkaline, volatile, boiler-feed additive in the steam in an acid-base reaction, the saturated steam having a pressure of from 15 to 90 psi; and, (c) recovering a filtered, purified, saturated, pressuriz-ed steam essentially free of particulate matter and volatile, alkaline, boiler-feed additive therein.
(a) passing the saturated, pressurized steam through the wall of a filter tube, which filter tube comprises a plurality of randomly disposed, nonwoven, inorganic glass fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns, and bonded at the junction of the fiber-crossover points with a bonding agent to form a porous, self-supporting filter tube to filter the particulate matter from the pressurized saturated steam;
(b) passing the particulate-free, filtered, pressurized saturated steam downstream through a bed of strong acid hydrogen-form ion-exchange resin material, the resin material composed of a high temperature, steam-resistant polymer, the resin material having a sufficient bed-depth to provide for the reaction of the strong acid hydrogen of the ion-exchange resin with the alkaline, volatile, boiler-feed additive in the steam in an acid-base reaction, the saturated steam having a pressure of from 15 to 90 psi; and, (c) recovering a filtered, purified, saturated, pressuriz-ed steam essentially free of particulate matter and volatile, alkaline, boiler-feed additive therein.
2. The method of claim 1 wherein the volatile, alkaline, boiler-feed additive is selected from the group consisting of cyclohexyl amine, diethylamino ethanol, hydrazine, morpholine, octadecyl amine and combinations thereof.
3. The method of claim 1 which includes passing the pres-surized saturated steam through the wall of a filter tube and thereafter directly axially upstream or downstream through a bed of a hydrogen-form sulfonic-acid ion-exchange resin material.
4. The method of claim 1 wherein the glass fibers of the filter tube comprise borosilicate-glass fibers having a diameter from 0.03 to 8 microns.
5. The method of claim 1 which includes passing the filtered steam from the filter tube directly through the wall of another filter tube on the opposite side and adjacent to a bed of the ion-exchange resin, whereby the saturated steam passes first through the one wall of the filter tube, through the ion-exchange resin bed, and thereafter directly through another adjacent wall of another filter tube.
6. The method of claim 1 wherein the strong acid hydrogen-form ion-exchange resin comprises a sulfonic acid ion-exchange resin.
7. The method of claim 1 wherein the bonding agent is selected from the group consisting of hardened fluorocarbon resin and hardened silicone resin.
8. The method of claim 1 which includes recovering pressurized steam having less than about 3 parts per million of volatile alkaline boiler-feed additive therein.
9. The method of claim 1 wherein the bed of ion-exchange resin is spaced apart from and directly downstream of the filter tube.
10. The method of claim 1 which includes passing the fil-tered, purified, saturated pressurized steam directly into a sterilizer vessel for the sterilization of medical instruments.
11. A method of preparing purified, saturated, pressurized steam from pressurized, saturated steam which contains particulate matter and a volatile, alkaline boiler-feed additive therein, which method comprises:
(a) passing the saturated, pressurized steam through the wall of a filter tube, which filter tube comprises a plurality of randomly disposed, nonwoven, inorganic glass fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns, and bonded at the junction of the fiber cross-over points with a bonding agent selected from the group consisting of hardened silicone resin and hardened fluorocarbon resin to form a porous, self-supporting filter tube to filter the particulate matter from the pressurized saturated steam;
(b) passing the particulate-free, filtered, pressurized saturated steam directly downstream through a bed of hydrogen-form, sulfonic acid, ion-exchange resin material, the resin material composed of a high temperature, steam-resistant polymer, the resin material having a sufficient bed-depth to provide for the reaction of the strong acid hydrogen of the sulfonic acid ion-exchange resin with the alkaline, volatile, boiler-feed additive in the steam in an acid-base reaction, the saturated steam having a pressure of from 15 to 90 psi; and, (c) recovering a filtered, purified, saturated, pressur-ized steam essentially free of particulate matter and having less than 3 parts per million of volatile, alkaline, boiler-feed additive therein.
(a) passing the saturated, pressurized steam through the wall of a filter tube, which filter tube comprises a plurality of randomly disposed, nonwoven, inorganic glass fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns, and bonded at the junction of the fiber cross-over points with a bonding agent selected from the group consisting of hardened silicone resin and hardened fluorocarbon resin to form a porous, self-supporting filter tube to filter the particulate matter from the pressurized saturated steam;
(b) passing the particulate-free, filtered, pressurized saturated steam directly downstream through a bed of hydrogen-form, sulfonic acid, ion-exchange resin material, the resin material composed of a high temperature, steam-resistant polymer, the resin material having a sufficient bed-depth to provide for the reaction of the strong acid hydrogen of the sulfonic acid ion-exchange resin with the alkaline, volatile, boiler-feed additive in the steam in an acid-base reaction, the saturated steam having a pressure of from 15 to 90 psi; and, (c) recovering a filtered, purified, saturated, pressur-ized steam essentially free of particulate matter and having less than 3 parts per million of volatile, alkaline, boiler-feed additive therein.
12. A composite cartridge for the filtering and removing of particulate matter and boiler-feed additives in saturated pressur-ized steam, which cartridge comprises in combination:
(a) a porous, self-supporting filter tube which comprises a plurality of randomly disposed, nonwoven, inorganic fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns and bonded at the junction of the fiber cross-over points with a bonding agent, to form a porous self-supporting filter tube;
(b) a bed of particulate, hydrogen-form, strong-acid, ion-exchange resin material peripherally adjacent at least one wall of the filter tube; and (c) porous retaining means to retain the ion-exchange resin adjacent the wall of the filter tube, whereby saturated steam is passed through the wall of the filter tube and the bed of ion-exchange resin, to provide for a saturated steam with reduced particulate and boiler-feed additive contents.
(a) a porous, self-supporting filter tube which comprises a plurality of randomly disposed, nonwoven, inorganic fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns and bonded at the junction of the fiber cross-over points with a bonding agent, to form a porous self-supporting filter tube;
(b) a bed of particulate, hydrogen-form, strong-acid, ion-exchange resin material peripherally adjacent at least one wall of the filter tube; and (c) porous retaining means to retain the ion-exchange resin adjacent the wall of the filter tube, whereby saturated steam is passed through the wall of the filter tube and the bed of ion-exchange resin, to provide for a saturated steam with reduced particulate and boiler-feed additive contents.
13. The cartridge of claim 12 wherein the retaining means comprises a second filter tube, which filter tube comprises a plurality of randomly disposed, nonwoven, inorganic fibers having interstices therebetween, to define the porosity of the filter tube, the fibers haying a diameter of from 0.1 to 10 microns and bonded at the junction of the fiber cross-over points with a bonding agent, to form a porous, self-supporting filter tube.
14. The cartridge of claim 12 wherein the fibers comprise borosilicate-glass fibers having a diameter of from 0.03 to 8 microns.
15. The cartridge of claim 12 wherein the bonding agent is selected from the group consisting of hardened fluorocarbon resin and hardened silicone resin.
16. The cartridge of claim 12 wherein the retaining means is positioned internally of the filter tube, whereby flow of the saturated, pressurized steam is from the outside inwardly.
17. The cartridge of claim 12 which cartridge includes a central flow passage within the cartridge, end caps at each end of the filter tube and retaining means, one of the end caps being imperforate and the other end cap having a central flow passage therein for the introduction or withdrawl of saturated steam therefrom.
18. The cartridge of claim 12 wherein the ion-exchange resin material comprises a sulfonic-acid resin material.
19. A steam-stabilizer system which includes:
(a) a pressure vessel with an inlet to receive purified, pressurized steam and an outlet to discharge air;
(b) a steam inlet line to introduce steam to the vessel;
(c) a steam cartridge housing in the steam inlet line, the housing having an inlet line and an outlet line; and (d) the composite cartridge of claim 12 in the housing, to filter particulate matter and remove alkaline, volatile, boiler-feed additives from the steam introduced into the housing inlet line.
(a) a pressure vessel with an inlet to receive purified, pressurized steam and an outlet to discharge air;
(b) a steam inlet line to introduce steam to the vessel;
(c) a steam cartridge housing in the steam inlet line, the housing having an inlet line and an outlet line; and (d) the composite cartridge of claim 12 in the housing, to filter particulate matter and remove alkaline, volatile, boiler-feed additives from the steam introduced into the housing inlet line.
20. A composite cartridge for the filtering and removing of particulate matter and an alkaline, volatile, boiler-feed additive from pressurized, saturated steam, which cartridge comprises:
(a) a porous, self-supporting filter tube which comprises a plurality of randomly disposed, nonwoven, inorganic fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns and bonded at the junction of the fiber-crossover points with a bonding agent, to form a porous, self supporting filter tube;
(b) a cylindrical bed of hydrogen-form, strong-acid, ion-exchange resin material adjacent to and positioned axially of the saturated steam flowing through the filter and adjacent the filter tube, the bed containing an imperforate, cylindrical wall thereabout;
(c) an outlet for the discharge of filtered, pressurized, saturated steam substantially free of particulate matter and the volatile, boiler-feed additive, and (d) a perforate retaining means for the resin material extending across the diameter of the filter and the one end of the ion-exchange bed, whereby saturated steam, from which particulate material has been removed by the filter tube, passes axially through the retaining means into the bed of particulate ion-exchange resin and highly purified, filtered steam is discharged from the outlet of the ion-exchange resin bed.
(a) a porous, self-supporting filter tube which comprises a plurality of randomly disposed, nonwoven, inorganic fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns and bonded at the junction of the fiber-crossover points with a bonding agent, to form a porous, self supporting filter tube;
(b) a cylindrical bed of hydrogen-form, strong-acid, ion-exchange resin material adjacent to and positioned axially of the saturated steam flowing through the filter and adjacent the filter tube, the bed containing an imperforate, cylindrical wall thereabout;
(c) an outlet for the discharge of filtered, pressurized, saturated steam substantially free of particulate matter and the volatile, boiler-feed additive, and (d) a perforate retaining means for the resin material extending across the diameter of the filter and the one end of the ion-exchange bed, whereby saturated steam, from which particulate material has been removed by the filter tube, passes axially through the retaining means into the bed of particulate ion-exchange resin and highly purified, filtered steam is discharged from the outlet of the ion-exchange resin bed.
21. The cartridge of claim 20 wherein the fibers comprise borosilicate-glass fibers haying a diameter of from 0.03 to 8 microns.
22. The cartridge of claim 20 wherein the bonding agent is selected from the group consisting of hardened fluorocarbon resin and hardened silicone resin.
23. The cartridge of claim 20 which includes an end cap at the one end of the filter tube comprising an imperforate end cap extending across the diameter of the filter tube, and another end cap at the other end and extending across the ion-exchange resin, which end cap contains a steam discharge outlet.
24. The cartridge of claim 20 wherein the ion-exchange resin material comprises a particulate sulfonic-acid resin material.
25. A steam-stabilizer system which includes:
(a) a pressure vessel with an inlet to receive purified, pressurized steam and an outlet to discharge air;
(b) a steam inlet line to introduce steam to the vessel;
(c) a steam cartridge housing in the steam inlet line, the housing haying an inlet line and an outlet line; and (d) the composite cartridge of claim 20 in the housing, to filter particulate matter and remove an alkaline, volatile, boiler-feed additive from the steam introduced into the housing inlet line.
(a) a pressure vessel with an inlet to receive purified, pressurized steam and an outlet to discharge air;
(b) a steam inlet line to introduce steam to the vessel;
(c) a steam cartridge housing in the steam inlet line, the housing haying an inlet line and an outlet line; and (d) the composite cartridge of claim 20 in the housing, to filter particulate matter and remove an alkaline, volatile, boiler-feed additive from the steam introduced into the housing inlet line.
26. A steam-sterilizer system which comprises in combination:
(a) a pressure vessel having an inlet to receive and introduce into the interior of the vessel highly purified, filtered, pressurized steam and an outlet to discharge air and steam condensate;
(b) a composite-cartridge housing having an inlet to receive saturated, pressurized steam containing particulate matter and boiler-feed additives to be removed, and having an outlet to discharge highly purified, filtered, pressurized steam to and for use in the pressure vessel, the housing containing downstream of the housing inlet (i) a porous, self-supporting filter tube which comprises a plurality of randomly disposed, nonwoven, inorganic fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns and bonded at the junction of the fiber cross-over points with a bonding agent, to form a porous, self-supporting filter tube to filter the saturated steam.
(ii) a bed of strong-acid-form, ion-exchange resin material to react with the yolatile, alkaline, boiler-feed additives in the filtered steam, and to provide a highly purified, filtered, pressurized steam to the housing outlet, and (iii) a drain in the housing for the discharge of water containing nonvolatile, boiler-feed additive materials.
(a) a pressure vessel having an inlet to receive and introduce into the interior of the vessel highly purified, filtered, pressurized steam and an outlet to discharge air and steam condensate;
(b) a composite-cartridge housing having an inlet to receive saturated, pressurized steam containing particulate matter and boiler-feed additives to be removed, and having an outlet to discharge highly purified, filtered, pressurized steam to and for use in the pressure vessel, the housing containing downstream of the housing inlet (i) a porous, self-supporting filter tube which comprises a plurality of randomly disposed, nonwoven, inorganic fibers having interstices therebetween, to define the porosity of the filter tube, the fibers having a diameter of from 0.01 to 10 microns and bonded at the junction of the fiber cross-over points with a bonding agent, to form a porous, self-supporting filter tube to filter the saturated steam.
(ii) a bed of strong-acid-form, ion-exchange resin material to react with the yolatile, alkaline, boiler-feed additives in the filtered steam, and to provide a highly purified, filtered, pressurized steam to the housing outlet, and (iii) a drain in the housing for the discharge of water containing nonvolatile, boiler-feed additive materials.
27. The system of claim 26 wherein the ion-exchange resin material comprises a bed of sulfonic-acid, bead, resin material.
28. The system of claim 26 wherein the filter tube comprises borosilicate-glass fibers, and the bonding agent is selected from the group consisting of hardened fluorocarbon resin and hardened silicone resin.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000406621A CA1213715A (en) | 1982-07-05 | 1982-07-05 | Apparatus for and method of removing volatile boiler- feed additives from pressurized steam |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000406621A CA1213715A (en) | 1982-07-05 | 1982-07-05 | Apparatus for and method of removing volatile boiler- feed additives from pressurized steam |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1213715A true CA1213715A (en) | 1986-11-12 |
Family
ID=4123152
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000406621A Expired CA1213715A (en) | 1982-07-05 | 1982-07-05 | Apparatus for and method of removing volatile boiler- feed additives from pressurized steam |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1213715A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109173496A (en) * | 2018-09-29 | 2019-01-11 | 骆炉昌 | A kind of industrial fermentation compression type air filtration tank |
-
1982
- 1982-07-05 CA CA000406621A patent/CA1213715A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109173496A (en) * | 2018-09-29 | 2019-01-11 | 骆炉昌 | A kind of industrial fermentation compression type air filtration tank |
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