Air-cooled ammonia refrigeration systems and methods

Patent metadata

Field	Value
Publication number	US-11226143-B2
Application number	US-201916689574-A
Country	US
Kind code	B2
Filing date	Nov 20, 2019
Priority date	Jul 15, 2016
Publication date	Jan 18, 2022
Grant date	Jan 18, 2022

Abstract

In some embodiments, an air-cooled ammonia refrigeration system comprises: a plurality of air-cooled condensers, each having a heat exchanger and at least one axial fan and having a first operating state capable of condensing vaporous ammonia to form liquid ammonia; an evaporator coupled to the air-cooled condenser; a subcooler positioned between the air-cooled condenser and the evaporator; a compressor coupled to the evaporator; an oil cooler coupled to the compressor; and a plurality of valves coupled to the plurality of air-cooled condensers and having a first configuration corresponding to the first operating state of the plurality of air-cooled condensers, and a second configuration corresponding to a second operating state of one or more of the plurality of air-cooled condensers such that the one or more of the plurality of air-cooled condensers functions as an evaporator capable of evaporating liquid ammonia to form vaporous ammonia.

First claim

What is claimed is:

1. An air-cooled ammonia refrigeration system, the system comprising:
a plurality of air-cooled condensers, each of the plurality of air-cooled condensers comprising a heat exchanger and at least one axial fan, and the plurality of air-cooled condensers having a first operating state such that the plurality of air-cooled condensers are capable of condensing vaporous ammonia to form liquid ammonia by heat transfer;
an evaporator coupled to the plurality of air-cooled condensers and configured to evaporate a liquid ammonia received from the plurality of air-cooled condensers to form vaporous ammonia;
a subcooler positioned between the plurality of air-cooled condensers and the evaporator and configured to further remove heat from the liquid ammonia passing from the plurality of air-cooled condensers to the evaporator;
a compressor coupled to the evaporator and configured to compress the vaporous ammonia received from the evaporator;
an oil cooler coupled to the compressor and configured to remove heat from circulating oil in the compressor;
a plurality of valves coupled to the plurality of air-cooled condensers, the plurality of valves having a first configuration corresponding to the first operating state of the plurality of air-cooled condensers, and a second configuration corresponding to a second operating state of one or more of the plurality of air-cooled condensers such that in the second operating state the one or more of the plurality of air-cooled condensers functions as an evaporator capable of evaporating liquid ammonia to form vaporous ammonia by heat transfer;
a control circuit coupled to the plurality of air-cooled condensers, the control circuit configured to:
determine a head pressure of the plurality of air-cooled condensers; and
when the head pressure of the plurality of air-cooled condensers is lower than a predetermined lower value, determine that one or more of the plurality of air-cooled condensers should be converted from the first operating state to the second operating state; and

a water system coupled to the plurality of air-cooled condensers and the control circuit, the water system comprising a water source, a water pump, and a plurality of spray nozzles positioned below the plurality of air-cooled condenser, wherein the control circuit is configured to pulse atomized water through the plurality of spray nozzles to a surface of the plurality of air-cooled condensers when a head pressure of the plurality of air-cooled condensers is higher than a predetermined upper value.

2. The system of claim 1 , wherein the control circuit is further configured to automatically identify the one or more of the plurality of air-cooled condensers to convert from functioning in the first operating state to the second operating state.

3. The system of claim 2 , wherein the control circuit is further configured to determine that the one or more of the plurality of air-cooled condensers in the second operating state should be converted back to functioning in the first operating state in response to the head pressure of the plurality of air-cooled condensers.

4. The system of claim 3 , wherein the control circuit is further coupled to the plurality of valves, and the control circuit is further configured to automatically reconfigure the plurality of valves to convert the one or more of the plurality of air-cooled condensers from functioning in the first operating state to the second operating state and back to the first operating state in response to the head pressure of the plurality of air-cooled condensers.

5. The system of claim 1 , further comprising:
a high pressure receiver coupled to the plurality of air-cooled condensers; and
a recirculator coupled to the evaporator,
wherein the high pressure receiver receives the liquid ammonia from the plurality of air-cooled condensers in the first operating state, and the recirculator receives liquid ammonia from the high pressure receiver that has been cooled by the subcooler.

6. The system of claim 5 , wherein the high pressure receiver is further coupled to the compressor to provide liquid ammonia to cool the oil in the oil cooler that is coupled to the compressor.

7. The system of claim 1 , wherein the control circuit is further configured to intermittently reverse a rotation of the at least one axial fan of one or more of the plurality of air-cooled condensers to remove debris from the one or more of the plurality of air-cooled condensers based on at least one of predicted, forecasted, historical, detected, and real time environmental, seasonal, climate, and weather conditions for a location of the plurality of air-cooled condensers.

8. The system of claim 1 , wherein the control circuit is further configured to intermittently reverse a rotation of the at least one axial fan of one or more of the plurality of air-cooled condensers to remove debris from the one or more of the plurality of air-cooled condensers at predetermined intervals as part of a daily, weekly, monthly, or seasonal maintenance cycle.

9. A method of providing refrigeration using an air-cooled ammonia refrigeration system, the method comprising:
supplying a vaporous ammonia to a plurality of air-cooled condensers, each of the plurality of air-cooled condensers comprising a heat exchanger and at least one axial fan, and the plurality of air-cooled condensers having a plurality of valves coupled thereto, the plurality of valves having a first configuration corresponding to the first operating state of the plurality of air-cooled condensers in which the plurality of air-cooled condensers are capable of condensing vaporous ammonia to form liquid ammonia by heat transfer;
condensing the vaporous ammonia in the plurality of air-cooled condensers to form liquid ammonia;
flowing the liquid ammonia to an evaporator configured to evaporate the liquid ammonia to form vaporous ammonia;
flowing the vaporous ammonia back to the plurality of air-cooled condensers in the first operating state;
determining, using a control circuit coupled to the plurality of air-cooled condensers, a head pressure of the plurality of air-cooled condensers;
when the head pressure of the plurality of air-cooled condensers is lower than a predetermined lower value, converting one or more of the plurality of air-cooled condensers in the first operating state to a second operating state by reconfiguring the plurality of valves from the first configuration to a second configuration, the second configuration corresponding to the second operating state of the one or more of the plurality of air-cooled condensers in which the one or more of the plurality of air-cooled condensers functions as an evaporator capable of evaporating liquid ammonia to form vaporous ammonia by heat transfer;
flowing a portion of the liquid ammonia condensed by the plurality of air-cooled condensers in the first operating state to the one or more of the plurality of air-cooled condensers in the second operating state to evaporate the liquid ammonia received from the plurality of air-cooled condensers in the first operating state to form vaporous ammonia;
flowing the vaporous ammonia evaporated from the one or more of the plurality of air-cooled condensers in the second operating state back to the plurality of air-cooled condensers in the first operating state; and
pulsing, using the control circuit, atomized water through a plurality of spray nozzles positioned below the plurality of air-cooled condensers to a surface of the plurality of air-cooled condensers when a head pressure of the plurality of air-cooled condensers is higher than a predetermined upper value.

10. The method of claim 9 , further comprising automatically ident

Assignees

• Walmart Apollo Llc

Inventors

• Baker Steven Kent
• Braz Marcos Rente

Classifications

• F25B49/027 Primary

  Condenser control arrangements · CPC title

• F25B9/002

  characterised by the refrigerant · CPC title

• F25B39/04

  Condensers · CPC title

• F25B2500/16

  Lubrication · CPC title

• F25B2600/111

  of condenser fans · CPC title