Air-cooled heat exchanger cleaning and temperature control apparatus and method

Patent metadata

Field	Value
Publication number	US-10907914-B2
Application number	US-201815975439-A
Country	US
Kind code	B2
Filing date	May 9, 2018
Priority date	May 9, 2018
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

A system for the maintenance and operation of an air-cooled heat exchanger (ACHE) includes a plurality of spray tubes provided with spaced-apart nozzles permanently positioned between the finned heat exchange tubes and longitudinally aligned within the region of the finned-tube pitch. The system is operable in several modes, including cleaning where the flow of air is stopped and temperature-controlled pressurized water with an optional cleaning agent is discharged from the nozzles to dislodge dirt and debris from the finned surfaces while simultaneously cooling the hot process liquid. When extremes of ambient air temperatures preclude the forced air fans from achieving the target temperature range of the process liquid passing through the ACHE, refrigerated pressurized cooled water and compressed air in the form of a mist is discharged from the nozzles, or alternatively, pressurized heated air is discharged from the nozzles.

First claim

The invention claimed is:

1. A method for cleaning and/or cooling or heating an air-cooled heat exchanger (ACHE) operating in extremes of ambient air temperatures to maintain a process fluid at or within a predetermined target temperature or temperature range, the ACHE including an array of finned air-cooled tubes extending in fluid communication between opposing headers, the plurality of finned tubes being arranged horizontally into a plurality of vertically spaced-apart rows, the fumed tubes thereby defining parallel open regions in the array, the method comprising:
a. permanently installing at a position proximate a header at one end of the ACHE a common manifold configured to receive and transmit a pressurized fluid from an external source, the common manifold extending above and transverse to the top row of finned tubes;
b. providing a plurality of spray tubes, each of the spray tubes extending parallel to, and substantially coterminous in length with the finned tubes, the ends of the spray tubes opposite the common manifold being sealed, one of each of the spray tubes being positioned in one of the open regions defined by the spaced-apart rows of finned tubes, the spray tubes being provided with spaced-apart nozzles for discharging a pressurized fluid to contact the adjacent surfaces of the fins and the tubes;
c. providing a plurality of intermediate fluid conduits extending between, and in fluid communication with the common manifold and the ends of each of the spray tubes proximate the header for delivering the pressurized fluid from the common manifold to the nozzles of each of the spray tubes to thereby provide an integrated array of spray tubes positioned in the ACHE;
d. providing a source of pressurized temperature-controlled water that is in controlled fluid communication with the common manifold;
e. monitoring the temperature of the process fluid at a location proximate a location of discharge of the process fluid from the ACHE, where the method is practiced subject to one or more of the following conditions:
a first condition being that the controlled operation of the ACHE cannot achieve and/or maintain the target temperature of the process fluid, and the method comprises initiating a cleaning of the air-cooled finned tubes to remove dirt and dust by introducing into the common manifold for discharge through the nozzles a pressurized cleaning fluid to remove the dirt and dust from the finned tubes;
a second condition being that the ambient air temperature is so high that it exceeds the ability of the ACHE to reduce the process fluid temperature to the target temperature, wherein the method comprises:
i. supplying a controlled flow of pressurized cooling water from an external source to the common manifold for discharge through the nozzles to reduce the temperature of the process fluid;
ii. if the monitored temperature of the process fluid remains higher than the target temperature after step (e)(i) above, then introducing compressed air from an external source into the manifold with the cooling water and discharging a mist of water droplets in compressed air from the nozzles to effect increased evaporative cooling of the air passing over the fins to cool the process liquid to the target temperature;

a third condition being that the ambient air temperature is so low that the ACHE is unable to maintain the process fluid temperature at the targeted temperature, wherein the method comprises:
iii. introducing a controlled flow of pressurized hot air from an external source into the common manifold for discharge from the nozzles to increase the temperature of the process fluid; and
iv. if the monitored temperature of the process fluid remains lower than the target temperature after step (e)(iii) above, introducing a controlled flow of steam from an external source into the common manifold for discharge through the nozzles until the target temperature is achieved.

2. The method of claim 1 which further comprises controlling the speed and operation of one or more fans of the ACHE in response to changes in the ambient air temperature in order to achieve and/or maintain the process fluid target temperature.

3. The method of claim 1 where the cleaning fluid is selected from the group consisting of water, an aqueous solution of a detergent or chemical agent, and compressed air and particles of bicarbonate of soda, alone or with other abrasive particles, and combinations thereof.

4. The method of claim 3 in which the temperature of the cleaning fluid is controlled to cool the process fluid to the target temperature.

5. The method of claim 3 in which the cleaning fluid is water or an aqueous solution, and heated or cooled water from an external source is mixed with water at ambient temperature to provide the cleaning fluid at a temperature predetermined to effect the reduction in temperature of the process fluid to the target temperature when sprayed on the finned tubes.

6. The method of claim 3 in which one or more fans of the ACHE are turned off during the cleaning of the air-cooled finned tubes.

7. The method of claim 1 in which the temperature of the cooling water is controlled by mixing water cooled by a refrigeration apparatus at ambient temperature.

8. The method of claim 1 in which the temperature and/or flow rate of the cooling water sprayed through the nozzles in step (e)(i) is controlled to maintain the target temperature of the process fluid.

9. The method of claim 1 in which the temperature and/or flow rate of the hot air or steam sprayed through the nozzles in steps (e)(iii) or (e)(iv) is controlled to maintain the target temperature of the process fluid.

Assignees

• Saudi Arabian Oil Co

Inventors

• Al-Otaibi Abdullah M

Classifications

• F28F1/24

  and extending transversely (F28F1/38 takes precedence) · CPC title

• B08B3/08

  the liquid having chemical or dissolving effect · CPC title

• F28G9/00

  Cleaning by flushing or washing, e.g. with chemical solvents (appliances using jets of fluid for removing debris F28G1/16, F28G3/16) · CPC title

• F28D1/05341

  with multiple rows of conduits or with multi-channel conduits combined with a particular flow pattern, e.g. multi-row multi-stage radiators · CPC title

• F28G1/166 Primary

  from external surfaces of heat exchange conduits · CPC title