Method and apparatus for producing steam and uses of same

Claim 2

A steam generator (11) comprising, a plurality of preferably stacked, interconnected, vertically-oriented liquid-holding chambers, there being defined a top chamber and a bottom chamber, means 29 for introducing water into the top chamber, means (45, 47, 49) in each of said chambers above the bottom chamber for communicating overflow water from a higher chamber to a lower chamber, the bottom chamber having a drain means (33) for removing water reaching the bottom chamber, means (43) for heating the water in at least two of said chambers to create steam in each of said chambers, means (51) for conducting said steam from a lower chamber to the chambers above, the steam migrating upwardly to a collection zone (77), and means (31) for releasing said steam from said collection zone (77).

Claim 3

The steam generator of Claim 1 in which at least in the bottom chambers (17) and the chambers (15) below the top chamber (13), preferably in all chambers, heating means (43) are provided.

Claim 4

The steam generator of Claim 1 or 2 in which the means (31) for releating said steam are arranged to communicate with the upmost collecting zone (77).

Claim 5

A steam generator (11) especially according to one of the preceding claims comprising, a housing having a plurality of liquid holding walled chambers (13, 15, 17) in cascading, gravity-feed-­relation, there being a top chamber (13) and a bottom chamber (17), means (29) for introducing water into the top chamber, first passageway means (45, 47, 49) defined in said chambers (13, 15, 17) for feeding overflow water from a higher chamber to the next lower chamber, the bottom chamber (17) having a fluid drain means (33) for removing said water therefrom, means (43) for heating the water in each chamber to create steam in each of said chambers, second passageway means (51) defined in said chambers for conducting the steam from a lower chamber to the chambers above, and means (31) for controllably releasing the steam from the top chamber (13).

Claim 6

A steam generator (11) especially according to one of the preceding claims comprising, a plurality of interconnecting, vertically-stackable modules which when stacked together define a plurality of vertically-oriented chambers (13, 15, 17), there being defined a top chamber (13) and a bottom chamber (17), each of the chambers having a liquid reservoir (75) therein, at least one feed water inlet (29) that introduces feed water into the reservoir of the top chamber (13), the bottom chamber (17) having a feed water drain outlet (33) responsive to levels of feed water within the reservoir of the bottom chamber, an electrical heating system having a resistive coil disposed within the reservoir (75) of each chamber, each coil (43) producing sufficient energy to cause gentle boiling of the feed water, and a steam outlet (31) in the top chamber.

Claim 7

The steam generator of one of the preceding claims wherein said means (45, 47, 49) for communicating overflow water from a higher to a lower chamber comprises a plurality of drain tubes (45), each of which has an entry (47) in the higher chamber and an exit (49) in the chamber immediately below, the entry being set at an overflow level (0) in the higher chamber.

Claim 8

The steam generator of one of the preceding claims further comprising a gravity feed network of standtubes (43) having entries in a higher chamber and an exit in the chamber immediately below the entries being at a reservoir overflow level (0), and a network of steam passageways (51) in direct communication with adjacent chambers, each passageway having an inlet port in the uppermost portion of lower chamber and an outlet port in the chamber directly above, the outlet port being at a level above the overflow level (0).

Claim 9

The steam generator of one of the preceding claims wherein said means (51) for conducting steam comprises a plurality of passages, each passage having an inlet (53) in the uppermost portion of the lower chamber and an outlet (55) in the chamber immediately above, the outlet (55) being at a level above said overflow level (0).

Claim 10

The steam generator of one of the preceding claims wherein said means (31) for releasing said steam comprises a steam outlet in said top chamber (13).

Claim 11

The steam generator of one of the preceding claims wherein said means (43) for heating comprises an electrical resistive coil having a portion thereof below said overflow level (0).

Claim 12

The steam generator of one of the preceding claims wherein each resistive coil (43) converts approximately the same amount of electrical power to steam.

Claim 13

The steam generator of one of the preceding claims wherein each chamber (13, 15, 17) is made of non-­metallic material.

Claim 14

The steam generator of one of the preceding claims wherein each chamber (13, 15, 17) or module has a cylindrical shape.

Claim 15

The steam generator of one of the preceding claims wherein said water is combined with less than 20 % preferably 5 % to 10 % of liquid isopropyl alcohol.

Claim 16

The steam generator of one of the preceding claims wherein said first passageway means or feed network for feeding overflow water from a higher chamber to a lower chamber comprises a first plurality of standing tubes (43) defined in walls of said chambers, each with an entry (47) in the higher chamber and an exit (49) in the next lower chamber, the entry being set at an overflow level (0) in the higher chamber.

Claim 17

The steam generator of one of the preceding claims wherein said second passageway means or feed network for conducting steam comprises a second plurality of standing tubes (51) defined in walls of said chambers, each having an inlet (53) in the uppermost portion of the lower chamber and an outlet (55) in the chamber immediately above, the outlet (55) being at a level above said overflow level (0).

Claim 18

The steam generator of one of the preceding claims wherein said means for heating is operationally adjustable to have a liquid surface area to power ratio greater than 0.2 ft²/kW.

Claim 19

The steam generator of one of the preceding claims comprising a plurality of vertically stackable units held together in biased compression which build up the housing and/or the steam generator (11).

Claim 20

A steam generating and cleaning system comprising, a steam generator (11) especially according to one of the preceding claims capable of producing pure steam and having a steam outlet (31), an inert gas supply (109), a heated supply line (111) connected to the steam outlet of said steam generator and the inert gas supply, the supply line having a droplet separator means (113), means for controllably mixing the flow of the inert gas and the steam into the heated supply line (111), and a cleaning station (115) including an enclosure housing an object (117) with an exposed surface to be cleaned, the supply line connected to the cleaning station so as to pass the inert gas and steam over the exposed surface of the object supported in the cleaning station.

Claim 21

The system of Claim 19 wherein said steam generator (11) includes a plurality of vertically-stacked boiling chambers (13, 17, 19) in cascading gravity feed relation, there being an uppermost chamber (13) with a feed water inlet (29) and a steam outlet (31) therein, said steam generator (11) further including a means for conducting overflow feed water from a higher chamber to the chamber immediately below, there being a lowermost chamber (17) with a feed water drain (33) therein, each chamber having a heating means (43) for creating steam and having means for conducting the steam from lower chambers to the uppermost chamber.

Claim 22

The system of Claim 20 wherein said droplet separator (113) includes filter means.

Claim 25

Use of the steam generator (11) according to one of Claims 1 to 18 in a cleaning system of one of Claims 19 to 23.

Claim 27

The method of Claim 25 further defined by cleaning semiconductor wafer surfaces at said point of use.

Claim 28

The process of Claim 25 or 26 wherein said desired sequence of delivering filtered steam and inert gas comprises: (a) inert gas only for purging the enclosure, followed by (b) inert gas and steam for high velocity preblasting, followed by (c) steam only for forming condensate on said surface follwed by (d) steam and inert gas for post-blasting, followed by (e) inert gas only for drying the surface.

Claim 29

A steam generating and cleaning process comprising the steps of (a) providing a vertically-stacked multi-chambered steam generator especially according to one of Claims 1 to 18, the generator having a top and a bottom chamber, (b) introducing feed water into the top chamber, (c) establishing a reservoir of feed water in each chamber and a downward cascading flow of overflow feed water through the chambers with any excess being released by drain means in the bottom chamber, (d) heating the reservoir of feed water in each chamber to create steam, (e) allowing the created steam to collect in the top chamber, (f) controllably releasing the steam from the top chamber, (g) providing a supply of an inert gas, (h) selectively mixing the released steam with the inert gas in a supply line that is maintained at a temperature above the point of condensation, (i) filtering the mixed steam and inert gas, (j) delivering the filtered steam and inert gas in a desired sequence to pass over a surface of an object rotatably supported in an enclosure, and (k) spinning the object to throw off the formed condensate from the surface.

Claim 30

The process of claim 27 or 28 wherein said inert gas is nitrogen.