Cooling process

Abstract

A process for cooling a heated coolant, said process comprising: (a) passing a heated coolant to an evaporative cooling apparatus wherein the coolant is cooled by evaporation; (b) heating at least a portion of the coolant from step (a) to provide a heated coolant; (c) recycling at least a portion of the heated coolant from step (b) to step (a) to form a circuit; wherein the process further comprises passing at least a portion of the coolant to a reverse osmosis unit to form a retentate solution and a permeate solution; introducing at least a portion of the permeate solution into the circuit; and removing the retentate solution.

Claims

1. A process for cooling a heated coolant, comprising: (a) passing a heated coolant to an evaporative cooling apparatus, wherein the heated coolant is cooled by evaporation to provide a cooled coolant, and maintaining a pH of the cooled coolant below 6.5 by introducing an acidic gas comprising carbon dioxide into said cooled coolant; (b) heating at least a portion of the cooled coolant from step (a) to provide a heated coolant portion; (c) recycling at least a portion of the heated coolant portion from step (b) to step (a) to form a circuit; (d) passing at least a portion of the coolant selected from the group consisting of the cooled coolant, and the heated coolant portion to a reverse osmosis unit for forming a retentate solution and a permeate solution; (e) introducing at least a portion of the permeate solution into the circuit; and (f) removing the retentate solution.

2. The process according to claim 1, further comprising selecting and passing the heated coolant portion to the reverse osmosis unit.

3. The process according to claim 1, further comprising introducing the acidic gas to the coolant prior to heating the coolant.

4. The process according to claim 1, further comprising passing the coolant through an ultra-filtration unit.

5. The process according to claim 1, further comprising heating the coolant using a heat exchanger.

6. The process according to claim 1, wherein the evaporative cooling apparatus comprises a cooling tower.

7. The process according to claim 1, wherein the coolant is selected from the group consisting of river water, bore hole water (well water), mains water (tap water), and reclaimed waste water.

8. The process according to claim 1, wherein the coolant comprises additives selected from the group consisting of one scale inhibitor, a plurality of scale inhibitors, corrosion inhibitors, biocides, and mixtures thereof.

Description

(1) The present invention will now be described further, by way of example only, with reference to the following figures, in which:

(2) FIG. 1: shows a schematic diagram of a flow scheme for carrying out the process/apparatus according to an embodiment of the present invention.

(3) FIG. 2: shows a schematic diagram of a flow scheme for carrying out the process/apparatus according to an alternative embodiment of the present invention.

(4) FIG. 3: shows a schematic diagram of a flow scheme for carrying out the process/apparatus according to a further alternative embodiment of the present invention.

(5) The numbering on the drawing (FIG. 1) depicts the following features: 5 cooling circuit pump(s) 10 evaporative cooling apparatus, for example cooling tower (for example media packed). 15 CO.sub.2 storage vessel 20 CO.sub.2 gas 25 control means for introducing CO.sub.2 into the circuit 28 coolant introduced to the heat exchanger 30 heat exchanger 35 heated coolant from the heat exchanger 40 blow-down 45 direction of coolant recycling around circuit 50 cooled coolant 60 optional pre-treatment unit 65 retentate solution rejected 70 reverse osmosis (RO) unit 75 permeate solution 80 heated coolant introduced to evaporative cooling apparatus (approximately 15 to 35 C.) 90 optional booster pump flow (3.0 to 3.5 barg). 100 pond or reservoir

(6) Coolant (28) passing through the heat exchanger (30) is heated (from 28 to 35). As the coolant is heated the industrial process stream (not shown) is cooled. The heated coolant (35, 80) is passed from the heat exchanger to the evaporative cooling apparatus (10) where it is cooled by evaporation. The evaporative cooling apparatus (10) may be a cooling tower. At least a portion of the cooled coolant (50) is recirculated to the heat exchanger (30) where it is heated (from 28 to 35), and then recycled to the evaporative cooling apparatus (10) to form a coolant circuit of recirculating coolant. At least a portion of the coolant is passed from the coolant (or recirculating) circuit to a RO unit (70) to form a retentate solution (65) and a permeate solution (75). The retentate solution is removed from the circuit. At least a portion of the permeate solution (75) is introduced into the circuit. The permeate (75) may be returned into the cooling circuit directly via the pond (100)

(7) Thus, in one embodiment, at least a portion of the coolant in the recirculating circuit passes from the heat exchanger (30) to the RO unit (70) forming the permeate solution (75), which is introduced into the evaporative cooling apparatus (10), and which then passes back to the heat exchanger (30) and the process is repeated.

(8) The CO.sub.2 storage vessel (15) is in fluid communication with the circuit and CO.sub.2 gas (20) may be fed into the circuit using control means (25). In this embodiment, CO.sub.2 (20) is fed into the circuit upstream of the heat exchanger (30). This is advantageous as the increased CO.sub.2 reduces scaling in the heat exchanger (prolonging its useful life).

(9) Optionally one or more pumps (5) may be used to pump the coolant around the circuit.

(10) Optionally, the coolant in the circuit is fed into a pre-treatment unit (60). Preferably, the pre-treatment unit (60) removes or reduces and suspended particles and/or contaminants from the coolant. Preferably, the pre-treatment unit is positioned upstream of (before) the RO unit (70), such that the coolant is purified before entering the RO unit (70). This will prolong the life of the membrane in the RO unit by reducing scaling and/or fouling of the membrane.

(11) A portion of the coolant may be removed from the circuit as blow-down (40). Advantageously, concentrating the total dissolved solids in the retentate solution (65) which is removed from the system (circuit) reduces the amount of blow-down required.

(12) Make-up feed solution (coolant) can be added to the system as required (not shown).

(13) The process and/or apparatus may further comprise one or more pH and/or alkalinity meters, and/or conductivity meters.

(14) FIG. 2 shows another embodiment of the apparatus and process of the described invention. The reference numerals used in FIG. 2 correspond with those used in FIG. 1, but have been further annotated with the letter a. In this embodiment, the heat exchanger (30a) is positioned downstream of the reverse osmosis unit (70a) and CO.sub.2 gas (20) feed is upstream of the reverse osmosis unit (70a) and the heat exchanger (30a).

(15) FIG. 3 shows another embodiment of the apparatus and process of the present invention. The reference numerals used in FIG. 2 correspond with those used in FIG. 1, but have been further annotated with the letter b. In this embodiment, CO.sub.2 gas (20) feed is upstream of the reverse osmosis unit (70b) and downstream of the heat exchanger (30b).

(16) When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles a, an, the and said are intended to mean that there are one or more of the elements. The terms comprising, including and having are intended to be inclusive and mean that there may be additional elements other than the listed elements.

(17) The foregoing detailed description has been provided by way of explanation and illustration, and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments illustrated herein will be apparent to one of ordinary skill in the art, and remain within the scope of the appended claims and their equivalents.