US3291197A

US3291197A - Shot cleaning method for heat exchangers

Info

Publication number: US3291197A
Application number: US515307A
Authority: US
Inventors: Kollerup Vagn
Original assignee: Burmeister and Wains Motorog Maskinfabrik AS
Current assignee: Burmeister and Wain AS; Burmeister and Wains Motorog Maskinfabrik AS
Priority date: 1962-06-13
Filing date: 1965-12-21
Publication date: 1966-12-13
Anticipated expiration: 1983-12-13
Also published as: DK100513C; DE1286679B; GB993681A

Description

Dec. 13, 1966 v. KQLLERUP 3,291,197

SHOT CLEANING METHOD FOR HEAT EXCHANGERS Original Filed June 11. 1965 R/NSE L/OU/D 0mm /3 INVENTOR PRESSUR/ZED Vagn Kol/erup WATER /2 R/NSE BY ORNEYS United States Patent 3 Claims: or. 165-1) The present invention is a continuation of my earlier application Serial No. 287,013, filed on June 11, 1963, now abandoned.

The present invention relates to improvements in a method of operating ball or shot-cleaning installations associated with heat exchangers or similar units and in an arrangement for ball or shot'cleaning installations operating according to the inventive method.

In boiler plants and similar heating exchangers having heating surfaces which are exposed to deposits of fiyashes and soot, the heating surfaces may be cleaned by steel balls of 4 to 6 mm. being caused to cascade downwardly over the heating surfaces thereby dislodging and removing the deposits because of both the vibration produced and the impurities being directly carried away by the gravitating particles or balls.

Having passed the heating surfaces, the balls are mixed wit-h soot and fiyashes so that they must be cleaned before reuse. This cleaning process is, in the prior art shot-cleaning installations, effected by means of an air flow which first carries the accumulations along with the shot and subsequently passes one or more cyclones, wherein the dust is again separated from the air. A dust separated off is carried away in a dry condition.

Having been subjected to the above-mentioned cleaning process, the balls are conveyed upwards to an upper storing container so as to be ready for another passage through the boiler plant. This return or upward transportation of the balls may be performed mechanically by means of .a lift, or the balls may be carried upwardly by an airflow from a high-pressure blower.

In the known shot-cleaning installations, the separation of soot and ashes from the shot collected after the fall through the plant causes some diificulty. No satisfactory solution has so far been suggested for the removal of impurities present in a dry state. It is true that they can be discharged through the funnel of the boiler plant, but this is from. .a general hygenic view not at all satisfactory. It is therefore an object of the present invention to overcome the above-mentioned difficulties.

Thus, the invention relates to a method of operating shotor ball-cleaning installations associated with heat exchangers or similar units, where the balls are periodically supplied from an upper container to the unit, and having passed such unit, the balls are directed to a lower collecting container, from which, after separation from the soot and ashes sticking thereto, they are returned to the upper container for reuse. The characteristic feature of the inventive method resides in using a liquid flow for the separation of the dirt from the balls as well as for the transportation of the balls up to the upper container.

An installation operating according to the inventive method may be simpler in design than the prior art shotcleaning installations where the dirt is removed from the balls by means of a current of air. There is a. special advantage in the inventive method in that the dirt separated from the balls is present in a wet condition, e.g., suspended in Water, so that instead of being discharged 3,251,197 Patented Dec. 13, 1966 ICC? in the atmosphere, it can be discharged through, for example, a convenient sewage duct.

It is preferable that, between subsequent passages through the heat exchanger, the balls be stored in a liquid in the lower container. Thereby, drying of the balls is superfluous which would otherwise be required in order to prevent the balls from rusting onto one an-' other.

The liquid used in the invention is advantageously alkalized water. In such case, the balls cascading downwardly through the heat exchanger may have a neutralizing effect on any acidic soot deposits particularly if the balls are thoroughly wet during the fall. With a view thereto, the liquid or part thereof used for conveying the balls upwardly may be directed through the heat exchanger or the corresponding unit together with the balls when the cleaning is performed.

Further, the invention relates to a ballor shot-cleaning installation working according to the above-explained method and which comprises one or more upper ball delivery containers and one or more lower collecting containers having an ejector for conveying the balls to the upper container or containers. The characteristic of the device according to the invention is that the collecting container or each of such containers comprises, in addition to the liquid-operated ejector at the bot-tom, one or more rinsing liquid inlets and one or more outlets for discharging the rinsing liquid containing soot and ashes from the balls falling through the liquid. During the passage downward through the collecting container, the cleaning balls coming from the heat exchanger encounter an upwardly directed liquid fiow, e.g., a water flow, the velocity of which is slightly lower than the falling velocity of the balls in water. The liquid flow will therefore, carry off the soot particles and other impurities carried from the heating surfaces by the balls. The impurities practically always have a specific gravity less than that of the balls so that their falling velocity in the liquid will also be lower than that of the balls. Thus, it is possible to obtain, in the collecting container. an effective separation of soot and ashes from the cleaning balls, and the dirt separated off will be carried away by the flow of rinsing liquid.

An embodiment of the cleaning plant comprising the arrangement according to the invention will in the following be described in detail with reference to the accompanying drawing which illustrates the invention in section.

The unit to be cleaned, e.g., the heating surfaces of a boiler plant has been indicated purely diagrammatically and is noted by reference numeral 1. The ball-cleaning installation as such consists essentially of an upper container 2 for delivering cleaning balls to the unit 1 and a lower container '3 for collecting the balls and dirt coming from said unit. If so desired, the installation may comprise a plurality of upper containers 2 and/or a plurality of lower containers 3. The cleaning balls are delivered from the bottom of the upper container 2 through a pipe 4 having a spreader body 5 and fall through the unit being cleaned to a collecting hopper 16 and a pipe 6 into the lower container 3. This latter container comprises an inlet for rinsing liquid, e.g., alkalized water, flowing upwardly through the container and in so doing encounters the falling balls.

The pipe 6 is in communication with the lower container via a collecting box 8 under which a short tube or socket 9 leads into the container 3. Through the same socket, rinsing liquid flows out of the container 3 as indicated by arrows, and the supply of rinsing liquid is so adjusted that the upwards velocity (indicated by small arrows) of the rinsing liquid within the socket 9 is lower than the falling velocity (indicated by the single broken arrow) of the balls 17 in the liquid. Thereby the liquid flow will carry dirt away from the balls but it will not prevent the latter from falling down to the bottom of the collecting container 3. The used rinsing liquid flows through the collecting box 8 into an outlet 10 which in the interest of safety may be provided with a ball trap 11 from which the impurified rinsing liquid can be directed to a sewer or filtering means if it is desired to reuse the liquid.

In the lower part of the collecting container 3 there is built in a liquid-operated ejector 12 which in an outlet pipe 13 produces a liquid flow sufficient for carrying the clean balls away and conveying them up to the upper container 2 to which the pipe 13 connects, as indicated by the series of arrows. The lower part of collecting container 3 may be provided with a drainage and rinsing pipe 14 through which impurified rinsing liquid may be directed to the sewer.

In the upper container 2 the liquid used for rinsing the balls has a rule to be separated from the balls prior to their being delivered to the unit 1. This separation may be effected by means of a strainer plate 18 and the liquid may leave the container through an outlet 15. The level of the liquid 19 in the upper container would be largely determined by the opening of the outlet 15.

The equipment, such as liquid pumps and operating handles required for operating the plant, is, in the interest of clarity, left out of the drawing.

The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore to be embraced therein.

What is claimed is:

1. In the method of cleaning surfaces of gas swept transmission units by means of solid cleaning shot which are periodically delivered from an upper container so as to rebound by gravity against said surfaces for loosening dirt particles therefrom, and then pass to a lower collecting container from which the cleaning shot are returned to said upper container, the step of using a first liquid fluid flow for separating off and carrying away the dirt particles from said cleaning shot and a second liquid fluid flow for returning the cleaning shot to the upper container, said first liquid fluid flow being directed against the flow of said shot as they are collected, said liquid fluid having a velocity less than the velocity of the falling shot in the liquid but greater than the velocity of said dirt particles.

2. A method of cleaning gas swept transmission surfaces according to claim 1 wherein the cleaning shot between passages through said unit are stored below the level of a liquid supply in the lower collecting container.

3. A method of cleaning gas swept heat transmission surfaces according to claim 1 wherein at least part of the liquid fluid used for returning the cleaning shot to the upper container is delivered from said container to the heat transmission surfaces together with said cleaning shot.

References Cited by the Examiner UNITED STATES PATENTS 1,795,348 3/1931 Schmidt 165 2,670,723 3/1954 Clarkson -95 3,062,508 11/1962 Braddon 165-95 FOREIGN PATENTS 525,076 12/1953 Belgium.

ROBERT A. OLEARY, Primary Examiner.

C. SUKALO, Assistant Examiner.

Claims

1. IN THE METHOD OF CLEANING SURFACES OF GAS SWEPT TRANSMISSION UNITS BY MEANS OF SOLID CLEANING SHOT WHICH ARE PERIODICALLY DELIVERED FROM AN UPPER CONTAINER SO AS TO REBOUND BY GRAVITY AGAINST SAID SURFACES FOR LOOSENING DIRT PARTICLES THEREFROM, AND THEN PASS TO A LOWER COLLECTING CONTAINER FROM WHICH THE CLEANING SHOT ARE RETURNED TO SAID UPPER CONTAINER, THE STEP OF USING A FIRST LIQUID FLUID FLOW FOR SEPARATING OFF AND CARRYING AWAY THE DIRT PARTICLES FROM SAID CLEANING SHOT AND A SECOND LIQUID FLUID FLOW ARE RETURNING THE CLEANING SHOT TO THE UPPER