Method and apparatus for utilizing heat content in waste water

• US 4,243,522 A
• Filed: 06/21/1979
• Issued: 01/06/1981
• Est. Priority Date: 06/22/1978
• Status: Expired due to Term

• Current Assignee: Kruger A/S
• Original Assignee: Kruger A/S
• Inventors: Ter-Borch, Poul E., Jorgensen, Ernst K., Baumgarten, Per
• Primary Examiner(s): Therkorn, Ernest G.
• Application Number:
  US06/050,537
• Time in Patent Office: 565 Days
• Field of Search: 210/7, 210/10, 210/12, 210/15, 210/71, 210/3, 210/175, 210/181, 210/182, 210/177, 210/178, 210/104, 210/123, 210/127, 210/97, 210/101, 62/238 E, 62/324 D
• US Class Current: 210/774
• CPC Class Codes: C02F 1/02 by heating methods of steam generation F22B; preheating boiler feed-water or accumulating preheated boiler feed-water F22D
• CPC Class Codes: C02F 1/04 by distillation or evaporation
• CPC Class Codes: F25B 30/06 characterised by the source of low potential heat
• CPC Class Codes: Y10S 210/918 Miscellaneous specific techniques

Abstract

Method and apparatus for utilizing the heat content in waste water which has passed through a biological purification plant, the last step of which comprises subjecting the waste water to sedimentation in a settlement tank. A heat pump is provided having an evaporator section which is heated by means of the waste water which has been purified in the settlement tank which is directed to it through a first conduit. During periods in which the flow rate of the waste water through the purification plant is less than the average flow rate which corresponds to the capacity of the heat pump, at least a portion of the waste water which flows through the evaporator of the heat pump is recirculated to the settlement tank, the latter being utilized as a heat reservoir according to the present invention.

Claims

1. A method for utilizing the heat content of waste water which has passed through a biological waste water purification plant at a variable flow rate from which an average flow rate can be obtained, the last operation in said plant comprising directing the waste water into a sedimentation tank wherein the waste water is substantially purified, comprising the steps of:

directing a flow of the substantially purified waste water from the sedimentation tank to the evaporator of a heat pump having a capacity substantially corresponding to the average flow rate so that the evaporator is heated; and

during periods in which the flow rate of the waste water is below said average flow rate, recirculating at least a portion of the waste water flowing through the evaporator back into the settlement tank which thereby functions as a heat reservoir.

2. Apparatus for utilizing the heat content of waste water which has passed through a biological waste water purification plant at a variable flow rate from which an average flow rate can be determined, the last operation in said plant comprising directing the waste water into a sedimentation tank wherein the waste water is substantially purified, comprising:

a settlement tank having an inlet through which said waste water enters said tank;

a heat pump having a capacity substantially corresponding to the average flow rate having an evaporator section;

first conduit means for directing said waste water from said settlement tank to said heat pump evaporator section to provide heat thereto;

second conduit means for recirculating at least a portion of said waste water from said heat pump evaporator section to said settlement tank; and

valve means disposed in said second conduit means for directing, during periods in which the flow rate of the waste water through said settlement tank is below said average flow rate, at least a portion of said waste water to said settlement tank through said second conduit means, said settlement tank thereby functioning as a heat reservoir.

3. Apparatus as recited in claim 2 further including pump means located in said first conduit means, said pump means including a reservoir in which the waste water rises to a certain level, said valve means being controlled by the level of the waste water which accumulates in the pump reservoir.