US3565164A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control of an air-cooled heat exchanger
Assignee: Dow Chemical Co
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Filing: 1969-07-07
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Granted: 1971-02-23
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Expires: 1989-07-07
Abstract
Abstract An air-cooled heat exchanger provided with a reversible pitch fan is controlled against excessive temperature swing in the material being cooled by the use of temperature-sensing elements and control circuitry which set the pitch of the fan for forward flow, reverse flow or feathering.
Inventors
- 👤 Paul E Kline
- 👤 Charles E Fahlgren
- 👤 Merlin R Kitchen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:27
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/1927; G05D23/193; G05D23/1931; G05D23/20; G05D23/22
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
172 words
A method for controlling the temperature of a process fluid within an air-cooled heat exchanger wherein air is forced through the heat exchanger by a reversible air-forwarding means, the reversible air-forwarding means being capable of assuming three conditions: (1) forwarding air into the heat exchanger; (2) withdrawing air from the heat exchanger, and (3) no airflow, the heat exchanger having an air intake end and an air discharge end, the steps of the method comprising: sensing the temperature of the process fluid adjacent the air intake end and adjacent the air outlet end; selecting predetermined temperatures above the freezing point of the process fluid; forwarding air through the heat exchanger when both the inlet and outlet temperatures are above predetermined temperatures; causing air to flow from the outlet end to the inlet end when the temperature adjacent the inlet end is below a predetermined temperature; and when the temperature at the inlet and outlet ends is below the predetermined temperatures, stopping flow of air through the heat exchanger by the forwarding means.
Claim 2
Independent Claim
172 words
A method for controlling the temperature of a process fluid within an air-cooled heat exchanger wherein air is forced through the heat exchanger by a reversible air-forwarding means, the reversible air-forwarding means being capable of assuming three conditions: (1) forwarding air into the heat exchanger; (2) withdrawing air from the heat exchanger, and (3) no airflow, the heat exchanger having an air intake end and an air discharge end, the steps of the method comprising: sensing the temperature of the process fluid adjacent the air intake end and adjacent the air outlet end; selecting predetermined temperatures above the freezing point of the process fluid; forwarding air through the heat exchanger when both the inlet and outlet temperatures are above predetermined temperatures; causing air to flow from the outlet end to the inlet end when the temperature adjacent the inlet end is below a predetermined temperature; and when the temperature at the inlet and outlet ends is below the predetermined temperatures, stopping flow of air through the heat exchanger by the forwarding means.
Claim 3
Independent Claim
157 words
A method for controlling the temperature of an air-cooled heat exchanger wherein the air-cooled heat exchanger for cooling a process fluid comprises a plurality of tubular heat exchange members in combination with inlet and outlet headers, an air-forwarding means comprising a motor-driven reversible pitch fan adapted to cause air to flow over the tubular members, the heat exchanger having an inlet end and an outlet end, the steps of the method comprising: sensing the temperature of the process fluid at the inlet and outlet ends of the heat exchanger; forwarding air from the inlet to the outlet end when the temperatures of the process fluid are above a predetermined temperature above the freezing point thereof; when the temperature at the inlet end is below the predetermined temperature, reversing the pitch of the fan, thereby reversing the direction of airflow; and when the temperature at the inlet and outlet ends is below the predetermined temperature, feathering the fan.
Claim 4
Independent Claim
157 words
A method for controlling the temperature of an air-cooled heat exchanger wherein the air-cooled heat exchanger for cooling a process fluid comprises a plurality of tubular heat exchange members in combination with inlet and outlet headers, an air-forwarding means comprising a motor-driven reversible pitch fan adapted to cause air to flow over the tubular members, the heat exchanger having an inlet end and an outlet end, the steps of the method comprising: sensing the temperature of the process fluid at the inlet and outlet ends of the heat exchanger; forwarding air from the inlet to the outlet end when the temperatures of the process fluid are above a predetermined temperature above the freezing point thereof; when the temperature at the inlet end is below the predetermined temperature, reversing the pitch of the fan, thereby reversing the direction of airflow; and when the temperature at the inlet and outlet ends is below the predetermined temperature, feathering the fan.
Claim 5
Dependent Claim
123 words
An air-cooled heat exchanger temperature control means comprising: first and second temperature-sensing means adapted to be disposed at the inlet and outlet ends of an air-cooled heat exchanger, respectively, to sense the temperature of a process fluid flowing therein; an air-forwarding control means capable of at least three speeds: forward, reverse and off; means in cooperative combination with the temperature-sensing means and the control means to provide a signal permitting forward flow of air when first and second sensing means are above a predetermined temperature; means providing a reverse flow when temperature adjacent the inlet end is below a predetermined temperature; and means to cause the air-forwarding means to be in the off condition when both temperature-sensing means indicate temperatures below predetermined values.
Claim 6
Dependent Claim
123 words
An air-cooled heat exchanger temperature control means comprising: first and second temperature-sensing means adapted to be disposed at the inlet and outlet ends of an air-cooled heat exchanger, respectively, to sense the temperature of a process fluid flowing therein; an air-forwarding control means capable of at least three speeds: forward, reverse and off; means in cooperative combination with the temperature-sensing means and the control means to provide a signal permitting forward flow of air when first and second sensing means are above a predetermined temperature; means providing a reverse flow when temperature adjacent the inlet end is below a predetermined temperature; and means to cause the air-forwarding means to be in the off condition when both temperature-sensing means indicate temperatures below predetermined values.
Claim 7
Dependent Claim
187 words
An air-cooled heat exchanger comprising: a first header; a second header; process fluid-carrying tubes extending between and being in fluid-carrying cooperation with the headers, the tubes having outlet ends in communication with an outlet header; an air-forwarding means, the air-forwarding means comprising: a motor; and a fan, the fan adapted to force air through the heat exchanger from the heat exchanger inlet end to the heat exchanger outlet end, the fan being of reversible pitch and capable of being feathered; a first temperature-sensing element in operative combination with the discharge end of the heat exchanger tube adjacent the inlet end, the temperature-sensing element being in cooperative combination with: a signal-providing means, said signal-providing means adapted to cause reversal of the pitch of the fan; a second temperature-sensing element disposed within the heat exchange tube associated with the outlet end of a heat exchange tube at the outlet end of the heat exchanger, the temperature-sensing means being in cooperative combination with: a signal-providing means which is adapted to feather the fan when the temperature is below the predetermined temperature as indicated by the first and second temperature-sensing elements.
Claim 8
Dependent Claim
187 words
An air-cooled heat exchanger comprising: a first header; a second header; process fluid-carrying tubes extending between and being in fluid-carrying cooperation with the headers, the tubes having outlet ends in communication with an outlet header; an air-forwarding means, the air-forwarding means comprising: a motor; and a fan, the fan adapted to force air through the heat exchanger from the heat exchanger inlet end to the heat exchanger outlet end, the fan being of reversible pitch and capable of being feathered; a first temperature-sensing element in operative combination with the discharge end of the heat exchanger tube adjacent the inlet end, the temperature-sensing element being in cooperative combination with: a signal-providing means, said signal-providing means adapted to cause reversal of the pitch of the fan; a second temperature-sensing element disposed within the heat exchange tube associated with the outlet end of a heat exchange tube at the outlet end of the heat exchanger, the temperature-sensing means being in cooperative combination with: a signal-providing means which is adapted to feather the fan when the temperature is below the predetermined temperature as indicated by the first and second temperature-sensing elements.
Claim 9
Dependent Claim
11 words
The apparatus of claim 4 wherein the fan is pneumatically controlled.
References Cited (Backward Citations)
US2826395A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-22 | 1974-08-24 | 1975-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-22 | 1978-08-24 | 1979-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-22 | 1982-08-24 | 1983-02-23 | $7700.00 | Window Closed / Lapsed |