CA1132410A

CA1132410A - Cleanable circumferentially finned heat exchanger

Info

Publication number: CA1132410A
Application number: CA350,660A
Authority: CA
Inventors: Henry J. Blaskowski
Original assignee: Combustion Engineering Inc
Current assignee: Combustion Engineering Inc
Priority date: 1979-09-04
Filing date: 1980-04-25
Publication date: 1982-09-28

Abstract

CLEANABLE CIRCUMFERENTIALLY FINNED HEAT EXCHANGER

Abstract of the Disclosure A heat exchanger for use in a particle laden gas stream and employing a plurality of circumferentially finned tubes. The tubes are arranged in line with respect to gas flow, and a soot blower uses an elongated tubular element with nozzles projecting steam downwardly between the in-line finned tubes. The soot blower is movable to traverse the heat exchanger. And the blowing medium may be interrupted when the soot blower is in line with the tubes.

Description

~ ~ 3~

i CLEANABLE CIRCUMFERENTIALLY FINNED HEAT EXCHANGER

Backaround of the Invention The invention relates to a heat exchanger arrangement and, in particular, to an arrangement for use in a particular laden gas stream.
With the present day trend moving towards coal firing, with ; the development moving in the direction of gasification systems handling charred-ash laden gases, the need for inexpensive, compact heat exchangers to hold down design cost has grown in importance.
10Spiral-finned surface affords one oF the best opportunities to affect the desired economy since it produces a material, space and cost saving. Moreover~ it is a form of extended surface that can be efficiently produced.
Although this surface has been applied with economy for gas-and oil-fired units, and for some coal-fired units, it is not possible to design spiral-finned heat exchangers for particulate-laden gases with assurance that surface failing will not be a problem. This di~fi-; culty ar;ses because there is no effective way to clean these surfaces as they are arranged. Rotating soot blowers are ineffective because of the staggered-lame tubing disposition and because of the presence of fins Summary of the Invention The invention comprises a heat exchanger arrangement using circumferentially finned tubing located within a gas flow duct with the tubes arranged in in-line relationship. A soot blower includes ~ ~3~

a tubular blowing elernent located adjacent the tube bank with the element arranged parallel to the tubes and ~ith nozzles in the element arranged to blow between the in-line tubes in a direction parallel to the gas flow. The soot blowing element traverses the width cf the duct so that it blows between each line of tubes in turn. The blowing medium may be interrupted when the nozzles are in line with the tubes of the tube bank.

Brief Description of the Draw~
Figure 1 is a sectional side elevation illustrating the heat exchange arrangement;
Figure 2 is a sectional view taken through 7ine 2-2 of Figure 1, and Figure 3 is a detail view taken in the area of the center of the soot blowing element as indicated by section 3-3 of Figure 2.

Description of the Preferred Embodiment A gas duct 10 confines a -flow 12 of particle laden hot gas.
Such gas may be from a coal-fired furnace or a coal gasifier. A
plurality of tubes 14 are circumferentially finned to supply ex-tended heating surface such as by the use of spiral fins. Such finning increases the effective heating surface of the tubes but is subject to plugging in a dust laden atmosphere.
A plurality of these tubes are connected in series flow relationship with a flow of fluid such as water forced through the tubes by means of pump 16. This may be a feedwater pump for a steam ~enerator or it may be a recirculating pump -for a gas-to-gas heat exchanger system with a fluid loop.
The axis of the tubes 14 is perpendicular to the flow of gases, and the tubes are arranged in a plurality of rows 18, 20, 22 transverse to the gas flow. The tubes of each row such as tubes 24, 26, 28 and 22 are in line with respect to gas flow. The tubing as arranged has a one-inch space between the edges of fins o-f adjacent tubes in ~he horizontal plane and one-half inch clear between fins in a vertical plane.
A soot blower 30 includes a tubular blowing element 32 having its axis parallel to -the finned tubes 14. It includes nozzle openings 34 on the bottom and top sides of the element arranged to direct the flow of fluid flowing through the element upwardly and downwardly parallel to the direction of the flowing gases.
A blowinq medium such as steam or air is passed through supply line 36 through control box 38 and thence through a tube 40 to the blowing element. In the location shown it can be seen that ; 10 a stream of blowing mediurn can be projected upwardly and/or down-wardly between the rows of tubes thereby achieving effective pene-tration and cleaning of the finned surfaces.
Control box 38 also includes means for supporting the soot blower assembly from support member 42. It also inc1udes means for traversing the element 32 across the width of the duct in a direction perpendicular to the axis of the element. Accordingly in traversing the duct the jet stream is blown through each of the series of open-ings between the in-line tubes.
The control box 38 also includes means to interrupt the flow of the blowing medium at those locations where the element 32 is in line with a row of tubes such as 18 20 or 22 thereby avoiding direct impingement on the tubing at close range. The blowing element 32 may be arranged to blow in both directions as illustrated or it may be arranged to blow only downwardly or upwardly depending on the arrangement of the tubing adjacent thereto.
.

Claims

1. A heat exchanger arrangement for transferring heat from the flow of particle laden hot gases to a flow of fluid com-prising: a duct for confining the flow of gases; a plurality of circumferentially finned tubes located within said duct, with the axis of said tubes perpendicular to the flow of gases, said tubes arranged in a plurality of rows transverse to the gas flow, the tubes of each row being in line with respect to gas flow; means for passing the flow of fluid through said finned tubes; a soot blower comprising a tubular blowing element having its axis parallel to said finned tubes and having nozzle openings directed parallel to the flow of gases and toward said circumferentially-finned tubes; means for traversing said tubular blowing element across said duct in a direc-tion perpendicular to the axis of said element; and means for passing a flow of blowing medium through said blowing element.

2. A heat exchanger arrangement as in Claim 1 having also:
means for interrupting the flow of flowing medium when the nozzles of said element are in alignment with said finned tubes.