US3667487A - Integrated chemical cleaning apparatus - Google Patents

Abstract

An integral chemical cleaning apparatus for supplying and recirculating compositions used in the process of removing scale, rust, grease and dirt coatings from internal metallic surfaces of closed industrial equipment where the stages of pickling, passivating and flushing are performed consecutively without change-over to separate devices for each of such stages of the process. The apparatus comprises a circulating pump forcing fluids from a supply source to valve means capable of directing flow in either of two directions for reverse cleaning and flushing and circulation back to said valve and on through a second valve means for discharge into one of a plurality of filters for removal of insoluble particles wherein said filtrate is collected in said supply source for recirculation into the system.

Description

United States Patent Schoenbeck et al.

[54] INTEGRATED CHEMICAL CLEANING APPARATUS [72] Inventors: Delbert L. Schoenbeck, Clarendon Hill;

Reece Kincaid, Crete, both of Ill.

Richardson Chemical Cleaning Service, Inc., Schererville, Ind.

[22] Filed: Dec. 11, 1970 [211 App]. No.: 97,160

[73] Assignee:

1 51 June 6,1972

2,223,791 12/1940 Morganetal ..l34/lll X 2,963,029 12/1960 Bock ..l34/95X [5 7] ABSTRACT An integral chemical cleaning apparatus for supplying and recirculating compositions used in the process of removing scale, rust, grease and dirt coatings from internal metallic surfaces of closed industrial equipment where the stages of pickling, passivating and flushing are performed consecutively without change-over to separate devices for each of such stages of the process. The apparatus comprises a circulating pump forcing fluids from a supply source to valve means capable of directing flow in either of two directions for reverse cleaning and flushing and circulation back to said valve and on through a second valve means for discharge into one of a plurality of filters for removal of insoluble particles wherein said filtrate is collected in said supply source for recirculation into the system.

4 Claims, 3 Drawing Figures INTEGRATED CHEMICAL CLEANING APPARATUS BACKGROUND OF THE INVENTION This invention relates to an apparatus for removing damaging deposits from internal walls of storage and manufacturing equipment which have become coated with films and encrustations of dirt, grease, rust and scale, etc. caused by adverse environmental conditions. More particularly, a single apparatus has been developed which is capable of performing all the essential tasks involved in industrial chemical cleaning. Generally, this type of cleaning is performed in four stages: degreasing, pickling, passivating, and flushing. Each of these stages ordinarily requires a separate and distinct set-up of apparatus to complete the job. l-leretofore, no single device has been available which was capable of efficiently performing all the above tasks. It is through the discovery of the present invention that the entire chemical cleaning process can be completed quickly and efficiently without resorting to more costly change-over equipment as each succeeding stage of the process is reached.

There is hardly an industry today that does not utilize storage containers, pipe lines, heaters, coolers, reaction vessels, distillation towers, exchangers, gas scrubbers, boilers, water softeners, precipitators, air conditioners, nuclear reactors, etc. for manufacturing purposes. Even before such equipment is put into use, soiling and fouling of all exposed surfaces begins, usually with the formation of scale, corrosion, grease and dirt deposits, lining their walls. In time, these deposits, if not removed, will have deleterious efiects on the equipment by reducing heat transfer, restrict fluid flow, impair plant efficiency, thereby increasing production costs. Therefore, to assure optimum output and efficiency of plant equipment, it is necessary to periodically clean the internal walls of such equipment.

In industrial cleaning, removal of encrustations and deposits and restoration of equipment is popularly done by reacting with and dissolving corrosion products and scale with the use of chemicals. Chemicals, since they are more efficient, have for the most part replaced the old mechanical methods of removal such as by hammering and chiseling.

Over the years it has become the recognized procedure in most cases of chemical cleaning to first clean or pickle the encrusted system with either organic or mineral acids such as hydrochloric, sulfuric, nitric, phosphoric, formic, hydroxyacetic, citric, and tartaric acids. Since pickled surfaces are quite reactive and quickly form metal oxides thereon, they are customarily protected from corrosion by passivation. The second step of passivation can be completed with solutions of sodium sulfite, hydrazine, or by adding sodium nitrite and ammonia to a pH of at least 9. Finally, after passivation, the system is flushed with oil or any media which is capable of removing and carrying any remaining insoluble material from the system.

Previous methods used in chemical cleaning processes have required individual devices for the pickling, passivating, and flushing stages, since no single assembly of pumps, piping, tank and filters were found to be entirely satisfactory for all three stages. With earlier devices, separate assemblies were required for each cleaning job, adding considerable extra expense for additional manhours taken by pipefitters and other skilled labor. It was not uncommon for pipefitters to spend twenty hours piping a pump, filter, tank, pipes and valves for reverse flow of the system being cleaned. Moreover, because additional time was needed for installation of separate devices, resulting in costly shut-down time of the equipment, it meant a loss of production and output for the manufacturer including idle hours for employees. On the other hand, the cleaning apparatus of the present invention requires only coupling to the system being cleaned and possibly to a steam generator as a source of heat, without requiring disconnection or hook-ups to a second or third pump. Further loss of time and greater expense were also sustained with earlier devices, even once they were assembled. It was found that individual pickling and flushing devices utilized single filter means for removing insoluble particles which required frequent cleaning to assure proper circulation of cleaning chemicals in the system. Devices having single filter systems, unlike those of the present invention, necessitated frequent shutdowns of the cleaning process, causing further delay and expense.

Unlike earlier chemical cleaning assemblies, the integrated device as disclosed herein has virtually eliminated the need for all tank truck requirements. With other devices, a tank truck with its pump would be used to clean the system, then another pump, filter and tank would be assembled to flush the system.

Accordingly, it is the principal object of this invention to provide an integrated chemical cleaning apparatus which is capable of pickling, passivating and flushing both preoperational and operational equipment without further change-over to other cleaning devices.

It is a further object of the present invention to provide an integrated chemical cleaning device with reverse flow means and a plurality of filters.

A still further object of the instant invention is to provide a complete chemical cleaning apparatus which eliminates the need for virtually all auxilliary pumping requirements.

Other objects, features, and advantages of this invention will become apparent to those skilled in the art from the drawing and specification describing the invention in more detail hereinafter.

Broadly, the invention is directed to a chemical cleaning apparatus for supplying and recirculating compositions used in industrial chemical cleaning. The apparatus comprises in combination a supply source for retaining liquid compositions, a pump adapted to withdraw the compositions from the source of supply for delivery to the equipment being cleaned and recirculation back to the source of supply, a plurality of filters, a first valve means adapted to control the direction of flow of the cleaning composition to and from said equipment and on to the source of supply and a second valve means adapted to alternate the flow of the compositions returning from the equipment through said filters prior to returning to the source of supply.

In certain types of chemical cleaning procedures, it may be desirable to heat the cleaning compositions before circulating into the equipment, in which case the source of supply, ordinarily a tank, is equipped with heating means.

ln most instances, it is preferable that the first valve means be an integral four-way, four-port valve fitted for reversing the direction of flow of the cleaning composition to and from the equipment. In addition, the second valve means is preferably an integral three-way, two-port valve adapted to release returning liquids to alternate filters. It is especially important to clean the filters of all insoluble residue to assure proper and continuous, steady flow through device and the system being cleaned. This can be accomplished by rotating the second valve means so that flow will be directed to a filter element other than the one that is to undergo cleaning. During the filter cleaning process, there is no shut-down of the apparatus, and circulation and filtering of fluids continues at the usual rate without interruption.

Having thus indicated the general nature of the invention, reference is made to the accompanying drawing forming a part of the specification and showing an illustrative embodiment of the invention, wherein:

FIG. 1 is a top view, flow diagram showing the circulation of cleaning compositions through valves, pump, pipes and filter assembly. The chemical cleaning apparatus is portably mounted on a skid.

FIG. 2 is a cross-sectional view of the reservoir tank or supply source with heating means and filters mounted in the interior of the tank.

FIG. 3 is a top-view of the supply source showing the floor of the tank and heating means secured within a chamber beneath the floor.

Referring to the drawings and a more detailed description of the invention, number 1 designates a source of rotary power for driving pump 2. Virtually any type of pump drive can be employed, such as electric motors, steam, gas and hydraulic turbines, gasoline, gas and diesel engines may also be used. Particularly useful are drive means which allow variable-speed operation which in turn permits greater control over pressure and flow rate during the process.

The above power source is used to drive pump 2 for moving solutions through the instant device and equipment to be cleaned. In most cleaning operations a centrifugal pump is appropriate, however, rotary pumps can also be effectively used. Then too, a reciprocating pump may be desirable when a pulsating type flow is desired. Because the solutions employed in the device are corrosive in character, pump 2 should be constructed of bronze for mildly corrosive conditions and perhaps nickel-base alloys and high-silicon cast iron when more caustic solutions are employed. Teflon lined pumps also provide added protection from corrosive solutions.

Between the pump discharge and one opening on valve 3, pipe 5 has been joined therewith. Number 3 is a four-way, four port valve capable of directing flow in either one of two directions for reverse flushing procedures. The position of valve 3 as shown in FIG. 1 is for normal flow output and will direct fluids through pipe 9 which has been joined to a second opening of said valve. Pipes 9 and 8 are thus fitted onto a boiler or other industrial equipment. Pipe 8 will serve as flow return as shown by FIG. 1 and is joined at a third opening of valve 3. Although not required in all instances, it is also advantageous to include valve members 10 and 11 on outflowinflow pipes 8 and 9. By using, for example, conventional gate valves on pipes 8 and 9 at a position proximal to the point of connection to the system cleaned, shut-down of the apparatus can be accomplished without draining solutions out of the system and will also prevent air from entering the system.

As previously indicated, out-flow direction as shown in FIG. 1 is normally through valve member 3 and pipe 9 with fluids returning by way of pipe 8, flow will then once again be through valve member 3. Joined at the fourth opening of valve 3 is a second valve member 4 having not fewer than three openings. One opening is joined to valve 3 either directly as, for example, by a flanged joint or by an intervening conduit 12 joining the two valves. The remaining two or more openings of valve member 4 are joined to a plurality of filter members 7 by pipe connections 13 and 14. Where valve 4 is a three way type, there will then be two filter members 7, and accordingly, if said valve is four-way, there will be three filter elements and so on. In most cases, however, valve 4 is a three way, two port valve which will accommodate two filter elements. In this regard, it will be seen that only one filter at a time will receive flow via valve 4, thus permitting cleaning of the remaining filter(s). After cleaning any insoluble residue from the filter element, the spindle or plug of valve 4 may then be rotated to reverse the flow to the cleaned filter. It can be seen that this feature assures continuous uninterrupted operation of the apparatus without necessitating shut-down for cleaning purposes.

Reservoir tank or supply source 6 will receive returning, filtered cleaning compositions for further circulation. The tank or reservoir well 44 is equipped with conduit 17 which is connected to the suction side of pump 2. Filtered solutions free of any objectionably large particles are thus recirculated to the device being cleaned. Optionally, conduit 17 may have a line strainer 19 to assure that no damaging insoluble material will reach the pump. Any conventional strainer or line filter will provide this added protection, thereby prolonging the life of the pump. Conduit 17 may also have a valve 18 such as a gate type, for draining fluids from the apparatus.

FIGS. 2 and 3 disclose more detailed views of the filtering apparatus which comprises in combination a filter basket housing 32, lid 26 and lid securing clamp 22 wherein said lid is either removably mounted from the basket housing or one end of the lid is mounted on a hinge which permits pivoting upwardly from the housing when clamp 22 is disengaged. Num bets 24 are the pipe connections carrying the flow from valve 4 to the filters. Filter element 30 is preferably a mesh screen basket or receptacle 28 which will catch all insoluble foreign matter larger than the screen opening. Screen gauge or mesh size can vary to meet acceptable ranges of particle sizes to suit the needs of the particular cleaning operation. Filter basket 28 is removably mounted for easy access and cleaning and is installed by first removing clamps 22 and lid 26 and inserting through orifice 42 at the bottom of the basket housing. The filter may be retained in the housing by any number of means, however, it has been found specially advantageous to employ filter elements which are flanged to overlap around the edges of housing orifice 42. This type of assembly assures secure retention of the filter and easy removal and insertion after cleanmg.

FIGS. 2 and 3 also show the filter assemblies mounted within the interior of the reservoir tank 36 and 55 respectively. Although they are preferably mounted in the interior of said tank to allow direct drainage of the filtrate for subsequent recirculation, filter assemblies do not have to be so positioned.

For example, filtering means alternatively can be placed out-- side the reservoir, the filtrate collected and discharged into the tank for recirculation.

Frequently, solutions used in chemical cleaning processes are heated to above normal temperatures prior to circulating in the system to be cleaned. The apparatus disclosed herein may heat cleaning compositions by various means. FIGS. 2 and 3 disclose an open tank and floor having hollow double walls as well as a double floor cavity. The double walls and floor are preferably lined with steam coils 25 and 53 or other heating elements. Steam is supplied at inlet 38 and 48 which passes to outlets 37 and 47. In immediate contact with the heating element is liquid media 40 and 46 which serves to transfer heat from the coils to the solutions in the tank. Water, ethylene glycol and the like may be used to fill the wall cavities at fill inlets 33 and 49. Vent couplings are 34 and 51. Alternatively, wall and floor cavities may be lined with electric heating coils. Still further heating means can be employed, whereby steam coils and electric heating elements are eliminated from wall hollows entirely, in which case a heating rod in direct contact with circulating solutions may be employed. Cleaning solutions can also be heated by applying a direct flame at the floor of the tank such as by a propane gas burner.

During the cleaning process, it is generally desirable to monitor both temperature of the cleaning compositions and pressure in the chemical cleaning apparatus. Temperature and pressure gauges 15 and 16 will assure optimal cleaning effect of the compositions and protection of the apparatus from breakdown. Acid and passivating solutions might be used at temperatures ranging from about to 200 F. Pressure gauges are particularly valuable for monitoring possible blockages in the system including excess stress placed on the pump by back pressure.

The entire cleaning apparatus disclosed herein can be portably mounted for easy transporting to the job site. For example, all the components of the device may be directly or indirectly mounted on I-beam skid support 20 to facilitate moving the unit. Alternatively, the device can be mounted on a wheel supported trailer or other draft type vehicle.

As indicated above, in chemical cleaning operations, corrosive compositions are routinely used. Mineral acids such as hydrochloric, sulfuric, and nitric acids, if used, may have an adverse effect on the instant apparatus. Basically, the pipes, etc. used in the construction of the apparatus are composed of standard black iron steel. Although the present device can be constructed from virtually any commercially available steel, including the more acid resistant alloy steels, when standard steels are used therein, the less corrosive organic acids such as citric and formic are preferred.

The pipes, valves, pump, motor, etc. set forth above are all standard components and fabricated equipment. For most industrial cleaning jobs, valves and pipes having a 4 inch diameter, a supply tank with dimensions of about 4 X 4 X 3 feet deep, and a pump output of about 300 gallons per minute will provide a unit of satisfactory capacity, in most cases. However, by altering the size of the components, its capacity can be increased or decreased accordingly.

In actual operation of the apparatus, the following procedure can be employed. After the system to be cleaned is checked for leaks, steam and flow inlets and outlets are coupled and made ready for operation. Initially, the system cleaned is flushed with 1-2 percent caustic soda solution for one to two hours for degreasing. The degreasing solution is drained from the apparatus and system and the same are flushed with water. Water flushing continues until a pH of not more than 7.5 is reached, at which time the discharge of flush water is closed and acid solution added to the system. Five to percent citric acid is used for pickling. Before and during pickling, the filters are inspected and cleaned at regular intervals by rotating the plug on the three-way valve, thereby redirecting discharge into the particular filter desired. During the 4 to 6 hour pickling period, the plug on the four-way valve is rotated for reverse flushing. The temperature of the pickling acid is maintained between 120 and 180 F. When citric acid is used, a passivating solution of sodium nitrite and ammonia adjusted to a pH of 9 can be added to the circulating acid without first draining it from the system and circulated for l to 2 hours at a temperature of between 120 and 140 F. All the solutions are then drained from the entire system while still hot. After the system is dried by blowing air, a check is made to determine if pickling and passivation are complete by removing small spool pieces of pipe at several points in the system. Inspection points are closed and if flushing is desired, flushing media is circulated for not less than 24 hours until no debris is deposited in the filter baskets after one hour of flushing. Filter baskets are cleaned or checked once per hour for the first 6 hours of flushing and once every 4 hours for the balance of the flush time. The media is drained and the equipment disconnected.

While operation of the device has been described in conjunction with the above explanation, this is illustrative only. Accordingly, many alternatives, modifications and variations of the apparatus and its operation will be apparent to those skilled in the art in light of the foregoing description, and it is therefore intended to embrace all such alternatives, modifications and variations as to fall within the spirit and broad scope of the appended claims.

We claim:

1. An apparatus for supplying and recirculating compositions used in the cleaning of industrial equipment containing a fluid treating system comprising in combination;

a. a source of supply for said compositions,

b. a pump adapted to withdraw said composition from said source of supply for delivery to said equipment and recirculation of the composition from said equipment to said source of supply,

c. a plurality of filters,

d. a first valve means adapted to control the fiow of composition to said equipment and from said equipment to said source of supply,

e. a second valve means adapted to alternate the flow through said filters of the composition discharged from said equipment prior to its return to the source of supply.

2. An apparatus as described in claim 1 wherein said first valve means is an integral four-way, four-port valve.

3. An apparatus as described in claim 2 wherein said second valve means is an integral three-way, three-port valve.

4. An apparatus as described in claim 3 wherein said source of supply is a tank equipped with heating means and the plurality of filters are mounted in said tank.

Claims (4)

1. An apparatus for supplying and recirculating compositions used in the cleaning of industrial equipment containing a fluid treating system comprising in combination; a. a source of supply for said compositions, b. a pump adapted to withdraw said composition from said source of supply for delivery to said equipment and recirculation of the composition from said equipment to said source of supply, c. a plurality of filters, d. a first valve means adapted to control the flow of composition to said equipment and from said equipment to said source of supply, e. a second valve means adapted to alternate the flow through said filters of the composition discharged from said equipment prior to its return to the source of supply.

2. An apparatus as described in claim 1 wherein said first valve means is an integral four-way, four-port valve.

3. An apparatus as described in claim 2 wherein said second valve means is an integral three-way, three-port valve.

4. An apparatus as described in claim 3 wherein said source of supply is a tank equipped with heating means and the plurality of filters are mounted in said tank.

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