CROSS REFERENCE TO RELATED APPLICATIONS

[000 Ij The present, application is related to U.S. Patent Application No. 12/353,821, entitled ^s4 Low Water Consumption Cooling Tower for Gasification Plants'' and filed on January 14. 20(K ⁾ , and U.S. Provisional Patent Application No. 61/084,070, entitled "Zero Discharge Waste Water System lor Gasification Plants" and filed on July 28, 2008, which are all assigned to the assignee of the present application. Each of these related applications are incorporated by reference in its entirety herein.

TECHNICAL FIELD

(0002) The application relates generally to power management for gasification facilities.

More particularly, the application relates to the management of electrical loads for gasification processes, such as for the production of substitute natural gas (SNG) from fossil fuels, to maximize the export of power during peak price periods, and minimize the export of power during offpeak price periods. In facilities that do not produce power, the import of power during peak price periods is minimized and the import of power during offpeak price periods is maximized.

BACKGROUND

(0003] Gasification is a process that enables the conversion of fossil fuels, such as coal or petroleum coke, imα SN(I hydrogen, or chemical feedstock. A number of processes in a gasification unit require large amounts of power or refrigeration. Currently, gasification facilities are operated under constant conditions and produce a constant amount of byproduct power, or basefoad power. Recent increases in power prices during peak usage periods have resulted in 'ess than optimum power production for current gasification facilities.

|0004] Accordingly, a need exists in the art for an Improved system for power management of a gasification unit for SNG production. SUMMARY

1000! ] The present invention satisfies ihe above-described need by providing systems and methods for controlling the power needs of a gasification facility.

{ 0002 j Gasification systems of the present invention include a gasification unit and a refrigeration storage system having a cooied medium _* such as ice water, for providing refrigeration to the gasification unit. The gasification unit may be a gasification unit for SNCi production and can include a gasifter, an air separation unit, an acid gas removal system, a CO; refrigeration system, or any combination thereof. In certain embodiments, the gasification unit includes three air separation units operating at 40% capacity and having liquid oxygen storage for additional refrigeration.

{00031 Methods of the present invention include manipulating the gasification systems of the present invention to maximize the export of power during peak price periods and minimize the export of power during offpeak price periods. In certain embodiments, methods include utilizing the refrigeration storage system to produce and store the cooled medium during offpeak price periods when power demands are low, and then using ihe cooled medium for supplying refrigeration to the gasification unit during peak price periods when the market price of power is high. In certain embodiments, power can be imported for utilisation during offpeak price periods when the market price of power is low. The power generated during offpeak price periods also can be exported during peak price periods. As a result, significant power revenue cat? be generated by the gasification systems of the present invention.

(0004 J These and other aspects, features and embodiments of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of illustrated embodiments exemplifying the best mode for carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THK DRAWINGS

[0005J Figure I is a graph illustrating wholesale power pricing vs. time of day for a single day in and around Houston, Texas, in June 2008.

[0006] Figure 2 illustrates an exemplary embodiment of a gasification unit for SN ⁽ I production. f 0007] Figure 3 illustrates an exemplary embodiment of an tee refrigeration system for supplying power to the gasification unit for SNG production of Figure 2.

{00081 Figure 4 is a graph comparing the power usage of existing baseload operations with the power usage of the load management system utilizing the ice refrigeration system of

Figure 3 in accordance with an exemplary embodiment.

[0009] The drawings illustrate only exemplary embodiments of the invention and are therefore not to be considered limiting of its scope, as the invention may admit to other equally effective embodiments.

BRIEF DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0010} The application is directed to systems and methods for control! ing the power needs of a gasification unit. In particular, the application is directed to manipulating an ice refrigeration storage system to control the electrical loads for the larger consumers of cooling in the gasification unit. The ice refrigeration storage system allows gasification facilities to maximize the export of power during peak price periods, minimize the export of power during offpeak price periods, control the export of power during mid-peak price periods, and supply power during emergency peak periods, in facilities thai do not produce power, the import of power during peak price periods is minimized and the import of power during offpeak price periods is maximized, As used herein, the term "peak price period" refers to a time period, typically mid-day, during which power demand is at a maximum and the market price of the power is at a premium, As used herein, the term "offpeak price period" refers to a time period, typically night, during which power demand is tu a minimum and the market price of the power is the lowest. As used herein, the term "mid-peak price period" refers to time periods, typically morning and evening, between the peak and offpeak price periods. As used herein, the term ''emergency peak period" refers to a ύπ\ε period, typically 1-2 hours, during impending blackout conditions.

[003 \ I The invention may be better understood by reading the following description of non-limiting, exemplary embodiments with reference to the attached drawings, wherein like parts of each of the figures are identified by the same reference characters, and which are briefly described as follows.

{0012] Figure I is a graph 100 illustrating an exemplary embodiment of wholesale power pricing in and around Houston, Texas _* USA, for a single day in June, 2008. The graph 100 shows the price per megawatt hour (MWh) vs. time of day. The power pricing is at a minimum during offpeak price period 1 10. The minimum price for power during the day is about S13/MWh. The offpeak price period HO typically occurs between about 2:00 a.m. and about 10:00 a.m. The power pricing is at a maximum during peak price period 120. The maximum price for power during the day is about $3227/ ^' M Wh. The peak price period i 20 typically occurs between about 2:00 p.ra. and about 10:00 p.m. Mid-peak price period 130 occurs between about 10:00 a.m. and about 2:00 p.m. and mid-peak price period NO occurs between about 10:00 p.m. and about 2:00 a.m.

[0013) in certain alternative embodiments, the offpeak price period 1 10 begins at about

12:00 a.m. and anas at about 7:00 a.m. or begins at about 1 :00 a.m. and ends at about 9:00 a.m. In certain alternative embodiments, the peak price period 120 begins at about 10:00 a.m. and ends at about 6:00 p.m. hi certain alternative embodiments, the mid-peak price period 130 begins at about 7:00 a.m. and enάs at about 10:00 a.m. In certain alternative embodiments, the mid-peak price period 140 begins at 6:00 p.m. and ends at 12:00 a.m. One having ordinary skill in the art can determine the offpeak, peak, and mid-peak price periods of a given day based on the power needs of a supplied area. Thus, these time periods may vary depending upon area location and demand requirements.

|0014] Referring to Figure 2, an exemplary embodiment of a gasification unit 200 for

SMG production is shown. The gasification unit 200 comprises a coke feed stream 202 ai about 9,500 tons per day (TPD) and a biomass feed stream 204 at about 5(K) TPO. Hie coke feed stream 202 and bicmass feed stream 204 enter .slurry preparation units 206 (5 units at 25 % capacity, or 5x25%) and produce a slurry stream 208. The slurry stream 208 can be formed by grinding or any other means known to one having ordinary skill in the art {00! S] hi alternative embodiments, the coke feed stream 202 and the biomass &cά stream 204 may be replaced with other suitable feed streams, such as hazardous waste, hydrocarbon streams, carbohydrate-based compounds, coal, and municipal waste. {0016] The slurry stream 208 enters gasifiers 210 (4x30%). Air separation units 212

(3x40% or 2x60%) also provide an oxygen (O>) stream 214 at about I l ,000 ITD to the gasifiers 230. The use of the oversized air separation units 212 can result in an increase in overall SNG production. The gasifiers 210 produce a slag stream 216 and a syngas stream 220. The slag stream 216 may comprise metals naturally occurring in the coke and biomass thαά streams 202, 204, and added minerals to control the melting point of the slag stream 216. The slag stream 216 may be utilized as an aggregate in concrete manufacturing and/or the manufacturing of other materials.

{ ^' 0017j The syngas stream 220 comprises about 35% carbon monoxide (CX)), about. 15% hydrogen (Ih)- about 40% water (H^O), and about 10% carbon dioxide. (CCh). The conversion of the slurry stream 208 and O? stream 214 into the slag stream 216 and the stream 220 is an exothermic process and as a result, a high pressure saturated steam stream 222 also is produced. [CK)ISj The stream 220 enters shift reactors 224 (4x30%). The shift reactors 224 are catalytic reactors that convert the stream 220 into a stream 22S. Specifically, ihe shift reactors 224 produce more H-> and CO; by reacting the 1 IjO with the CO. The stream 228 comprises about 15% CO, about 45% IU, and about 40% CO>. Jn certain embodiments, the shift reactors 224 include gas cooling capabilities.

[0019| The stream 228 enters acid gas removal systems 230 (2x50%). The acid gas removal systems 230 may utilize Selexol™ for hydrogen sulfide HhS) removal and CO2 capture. As a result, a C<h stream 232 at about 22,000 TPD is produced. The CO ₃ stream 232 is compressed in a compressor system 234. which includes a CO; refrigeration exchanger (not shown), and the resulting high pressure CCh stream 236 may then be utilised for enhanced oil recovery (EOR) (not shown) by pumping the CQ ₂ into the ground to increase the production of oil.

[002Oj The acid gas removal systems 230 also produce an add gas stream 238. The acid gas stream 238 enters sulfur recovery units 240 (3x50%) to produce a sulfur stream 242 and a recycle taU gas stream 244. The sulfur stream 242 comprises sulfur and can be sold to fertUisser plants and the like. The recycle tai! gas stream 244 comprises some sulfur and is recycled back into the acid gas removal systems 230.

[00211 The acid gas removal systems 230 also produce a stream 248 comprising mainly of CO and f-fe. Since the COi has been removed within the acid gas removal systems 230, the stream 248 comprises about 25% CC) and about 75% H> In certain embodiments, the stream 248 can be soid as syngas to market or consumed by other systems requiring the syngas (not shown). The syngas may be used as ammonia, methanol, or hydrogen, or be utilized in the production of power or chemicals.

10022] The stream 248 enters methanatioπ reactors 250 (2x50%). The methanation reactors 250 convert the stream 248 into a stream 254. The stream 254 comprises SNG at about I SO million standard cubic feet per day of gas (,MMSCFD) and can be sold to market or consumed by other systems requiring the syngas, in certain alternative embodiments, a portion of the stream 254 can enter combustion turbines (not shown) to produce power to be sold to market.

[0023] In addition, the high pressure saturated steam stream 222 from the gasi tiers 210 enters the methanation reactors 250. The conversion of the stream 248 into the stream 254 in the methanation reactors 250 is an exothermic reaction and as a result, the high pressure saturated steam stream 222 is converted to a high pressure superheated steam stream 258 at about 2,800 kilo pounds per hour (kpphj. The high pressure superheated steam stream 258 can be utilized in a steam turbine ( lx$ 20%) (not shown) to produce power to be soid to market or consumed by other systems requiring the power.

(0024 J In the exemplary embodiment of the gasification unit 200, the largest consumers of power or refrigeration needs are the air separation units 212, the acid gas removal systems 230, and the compressor system 234 for the compressing and cooling of the COj stream 232. [0025J Figure 3 illustrates an exemplary embodiment of an ice refrigeration storage system 300 for managing the power supply to the air separation unit 212, the acid gas removal system 230, and the compressor system 234 of the gasification unit 200 (Figure 2). The ice refrigeration storage system 300 comprises a cooling lower 302 coupled to a condenser water pump 304, The condenser water pump 304 pumps a cold water stream 306 from the cooling tower 302 to a water unit 31 Oa of a glycol chiller 310, The glycol chiller 310 is a heat exchanger that utilizes the cold water stream 306 to chiil a warm glycol stream 312 that enters a glycol unit about 370 million British thermal units per hour (MMBTU/h) and is at a temperature of about 25 ^W F. A hot water stream 314 exits the water unit 310a of (he glycol chiller 310 and returns to the cooling tower 302 for further cooling. Λ cold glycol stream 318 exits the glycol unit 310b of the glycol chiller 310 and Hows to a glycol pump 320. In certain embodiments, the cold glycol scream 31 S is at a temperature of about 20° F. Although this embodiment depicts a glycol chiller 3Hh any type of refrigerant chiller may be used without departing from the scope and spirit of the exemplary embodiment. Thus, although glycol is used within the glycol unh 310b, any refrigerant may be used that, is capable of forming ice within an ice storage unit 324, which is further discussed below.

(0026] The glycol pump 320 pumps the cold glycol stream 3 ! 8 through a thermal storage coil 322 housed in an ice storage unit 324. The thermal storage coll 322 is positioned such that a first terminus 322a of the thermal storage coil 322 is located at a top 324a of the ice storage unit 324 and a second terminus 322b of the thermal storage coil 322 is located at a bottom 324b of the ice storage unit 324. The thermal storage coil 322 also loops from side to side within die ice storage unit 324 to increase the length and surface area of the thermal storage coil 322 within the ice storage unit 324, The cold glycol stream 318 Ls converted to the warm glycol stream 312 as it exits the ice storage unit 324. The warm glycol .stream 312 is then led hack into the glycol chiller 310 and chilled for further reuse by the thermal storage coil 322. Although this embodiment depicts the first terminus 322a and the second terminus 322b at particular locations within the ice storage unit 324. the first terminus 322a and the second terminus 322b may be positioned at any location, either within or on the exterior of the ice storage unit 324 without departing from the scope and spirit of the exemplary embodiment. Further, although the thermal storage coil 322 has been depicted to be oriented in a serpentine manner, the thermal storage coil 322 may be oriented in any pattern, including, but. not limited to spiral, a diagonal serpentine, a vertical serpentine, circular, and rectangular, so long as the surface area is maximized to provide proper cooling to the ice/water within the ice storage unit 324 and surrounding the thermal storage coil 322 without departing from the scope and spirit of the exemplary embodiment. [0027] The ice storage unit 324 stores HjO 330 as mostly solid (ice) or mostly liquid

(water), As the cold glycol stream 318 is pumped through the thermal storage coil 322, at least a portion of the HaO 330 is converted from water to ice. The looped configuration of the thermal storage coil 322 facilitates the formation of sheets of ice between the loops of the thermal storage coil 322. In certain embodiments, the H ₂ O 330 is at a temperature of about 32° F. Jn certain embodiments, the ice storage unit 324 has a width of about 55 feet, a length of about 75 feet, a height of about 35 feet, and stores about 53,000 ton-h Of M ₂ O 330. In alternative embodiments, the ice storage unit 324 stores about 250,000 ton-h of ll^O 330. Although exemplary dimensions have been provided for the ice storage unit, the dimensions of the ice storage unit 324 can be different based on the amount of cooling required for the system 'and the time available for performing the cooling.

[002S] The ice refrigeration storage system 300 also comprises an air pump 334 which feeds air bubbles into the ice storage unit 324 via an air tube 335 located at the bottom of the ice storage unit 324. The air bubbles aid in preventing bridging of the ice sheets between the loops of the thermal storage coil 322 and facilitate the flow of water within the ice storage unit 324. [0029! An ice water pump 340 pumps a chilled water stream 342 comprising H;O 330 at about 32" F from the ice storage unit 324 to the air separation unit 212 at SJ ₅ (K)O gallons per minute (CJPM.) during offpeak price period 1 10 (Figure 1 } and 13,500 GPM during peak price period 120 (Figure 1), to the acid gas removal system 230 at 8,000 CJPM. and to the CO^ refrigeration exchanger 378 at 32,000 GPM.

[0030| The air separation unit 212 comprises an air stream 348 entering at a temperature of about 90° F. The air separation unit 2S2 operates at about 180 MMBTU/h during oitpeak price period I IO (Figure 1} and at about 95 MMBTU/h during peak price period 120 (Figure \ ). The air stream 348 is cooled by the chilled water stream 342 and exits the air separation unit 212 as air stream 350 at about 45* F. Chilling the air stream 348 to air stream 350 allows water in the air stream 348 to condense and increases the density of the air stream 350. [0031 ] The chilled water stream 342 exits the air separation unit 212 as heated water stream. 352a at 60" F after cooling the air stream 348. The heated water stream 352a enters a high temperature chiller 356. The high temperature chilkr 356 operates at about 160 MMBTU/h. The high temperature chiller 356 chills the heated water stream 352a to about 45 ^U F mά the heated water stream 352a exits the high temperature chiller 356 as chilled water stream 360. in certain embodiments, the high temperature chiller 356 operates only during the offpeak price period 110 (Figure I )- ϊn alternative embodiments, the high temperature chiller 356 operates during offpeak price period 1 10 (Figure I) and mid-peak price period 130 (Figure ! }. In alternative embodiments, the high temperature chiller 356 operates at a!! times, 10032] The acid gas removal system 230 comprises a Seiexo! ^{1 M} stream 362 entering at a temperature of about 90° F. The acid gas removal system 230 operates at about 100 MMBTU/h. The Selexoi ^;M stream 362 is cooled by the chilled water stream 342 and exits the acid gas removal system 230 as chilled Seiexoi ^{1 M} stream 364 at about 40° F. Although specific temperatures have been provided for the Se.!exol ^{! M} streams 362, 364, alternative embodiments may have different temperatures for the Seiexol ^iM streams 362, 364 without departing from the scope and spirit of the exemplary embodiment.

10033 \ The chilled water stream 342 exits the acid gas removal system 230 as heated water stream 352b at about 60° F after cooling the Se!exol ^{i M} stream 362. The heated water stream 352b enters the high temperature chiller 356, The high temperature chiller 356 chilis the heated water stream 352b to about 45" F and the healed water stream 352b exits the high temperature chiller 356 as chilled water stream 360. The operation of die high temperature chiller 356 has been previously described above.

100341 The compressor system 234 comprises a dry CO.; stream 36S entering a first heat exchanger 370 and exiting as a cooled CXh stream 376. The dry CO; stream 368 is at about 640 psig.. and is cooled from a temperature of about 90* F to about 60* F by a liquid CO∑ stream 374 at about 2200 psig ami about 50° F. The cooled CO> stream 376 enters the CO _? , refrigeration exchanger 378 and exits as cooled COj stream 382. The cooled CO? stream 376 is further eooied to about 50* F by the chilled water stream 342. The CO? refrigeration exchanger 378 operates at about 170 MMBTU/h. A pump 380 compresses and pumps the cooled CO2 stream 382. which is now the liquid CO;; stream 374. The liquid CO; stream 374 is utilized in the first Tteat exchanger 370, as previously discussed, and exits the first heat exchanger 370 as liquid CCb stream 386 at shorn 2200 psig and about 80° F.

(0035] The chiiied water stream 342 exits the CO≥ refrigeration exchanger 378 as water stream 390 having a temperature of about 45° F. The water stream 390 is combined with chilled water stream 360 to form water stream 392. The water stream 392 enters a low temperature chiller 394, The low temperature chiller 394 operates at about 300 MMBTU/h. The water stream 392 is further cooled to produce a water stream 39$ having a temperature of about 36° F. hi certain embodiments, the temperature of water stream 396 may range from about 33 ^a F to about 48 ° F. The water stream 396 is then fed into the ice storage unit 324 and mixed with the H-O 330. In certain embodiments, the low temperature chiller 394 operates only during the offpeak price period ! 10 (Figure 1 }. hi alternative embodiments, the low temperature chiller 394 operates during offpeak price period 1 \0 (Figure 1) and mid-peak price period i 30 (Figure 1 }. in alternative embodiments, the low temperature chiller 394 operates at ail times. (0036] Generally, the ice refrigeration storage system 300 is designed such that the glycol chilier 310, the high temperature chiller 356, and the low temperature chiller 394 operate during offpeak price period 1 10 (Figure 1). During the olTpeak price period I K ⁾ (Figure i). the export, of power is minimized and refrigeration (ice and liquid Oz) can be stored. During the mid-peak price period 130 (Figure 1 ), the glycol chiller 310 is not in operation, but the high temperature chiller 356 and the low temperature chiller 394 are in operation. During the peak price period 120 (Figure I), the glycol chiller 3 K), the high temperature chiller 356, and the Sow temperature chiller 394 are not in operation. The stored refrigeration can be utilized during the peak price period 120 (Figure !} while export of power can be maximized, in addition, power can be imported and utilized during the offpeak price period 1 IO (Figure I ) at a lower price than during the peak price period 120. Therefore, significant power revenue can be generated by the gasification unit 200 from peak price period power sales vs. baseload operation power sales. [0037J To facilitate a better understanding of the present invention, the following hypothetical example of certain aspects of certain embodiments is given. In no way should the following example be read to limit, or define, the scope of the invention.

KXAMPlJ:, f 0038] Figure 4 is a graph 4(.H) comparing the generated power usage of existing baseload operations with the generated power usage of the load management system utilizing the ice refrigeration system of Figure 3 in accordance with an exemplary embodiment. During baseioad operations, generated power is constantly supplied as follows: about 145 megawatts (MW) to air separation units 4!O ₅ about 40 MW for CO ₂ compression 420, about 30 MW for CO? refrigeration 430, about 25 MW for refrigeration of the solvent used in acid gas removal systems 440, about 20 MW for grinding of coal/coke 450, about 25 MW for miscellaneous use 460, and about 95 MW for export 470. Thus, the total generated power during baseload operations is about 380 MW.

(0039) The refrigeration storage system of the present invention operates based on the price period. The offpeak price period is about 2825 hours/year (h/y), the mid-peak price period is about 2825 h/y, the peak price period is about 3000 h/y. and the emergency peak period is about 10 h/y. In addition, a two-train operation shutdown is conducted during about JOO h/y. During the two-train operation shutdown, power is not generated and only power for CQχ compression 420 and miscellaneous use 460 is imported and consumed.

{ ^' 0040 J During the offpeak price period, generated power is supplied as follows: about

173 MW to air separation units 410, about 40 MW for CO ₂ compression 420, about 30 MW for CO ₂ refrigeration 430, about 25 MW for refrigeration of the solvent used in acid gas removal systems 440, about 20 MVV for grinding of coal/coke 450, about 25 MW for miscellaneous use 460, about 65 MW for ice storage 480, and about 2 MW for export 470. Thus, the total generated power during the offpeak price period operation is about 380 MW, which is similar to the total generated power during baseioad operations.

[0041 ] During the mid-peak price period, generated power is supplied as follows: about

173 MW to air separation unite 4.10, about 40 MW (or CO2 compression 420, about 30 MW for COj refrigeration 430, about 25 MW for refrigeration of the solvent used in acid gas removal systems 440, about 20 MW for grinding of coal/coke 450, about 25 MW for miscellaneous use 460, and about 67 MW for export 470. As shown, the generated power typically used for the ice storage 480 during the offpeak price period is now exported during the mid-peak price period. The total generated power during the mid-peak price period operation is about 3S0 MW, which is similar lύ ths total generated power during baseload operations. |0<>42} During She peak price period, generated power is supplied as follows: about 84

MW to air separation units 410. about 40 MW for CQj compression 420, about 20 MW for grinding of coal /coke 450. about 25 MW for miscellaneous use 460, and about 21 1 MW for export 470. As shown, the generated power typically uscά for CX ⁾ > refrigeration 430.. refrigeration of the solvent used in acid gas removal systems 440, and some of the generated power used for Ihe air separation units 410 during the mid-peak price period is now exported during the peak price period. Instead, power for CCh refrigeration 430, refrigeration of the solvent used in acid gas removal systems 440, and .some of the power for the air separation units 410 are provided by ice storage 480. Some of the non-essential systems may be turned off so as to increase the export of power during the peak price period. The total generated power during the peak price period operation is about 380 MW, which is similar to the total generated power during basebad operations,

[0043] During the emergency peak period, generated power is supplied as follows: about

40 MW for CCh compression 420. about 25 MW for miscellaneous use 460. and about 335 MW for export 470. Λs shown, the generated power typically used for the air separation units 410 and the grinding of coal/coke 450 during ihe peak price period is now exported during ihe emergency peak period. Additionally, about 120 MW additional generated power is produced during this emergency peak period. All of the non-essential systems are turned off so as to increase the export of power during the emergency peak period. The total generated power during the emergency peak period operation is about 500 MW. which is about 120 MW more than the total generated power during baseload operations.

[0044] During the two-train operation shutdown period, 35 MW of power is imported and distributed as follows: 20 MW for CCb compression 420 and 15 MW for miscellaneous use 460. i0045| To achieve the above results, 3x40% air separation units 410 with 12 hour liquid

O>2 storage, 16 hour offpeak see production for CO ₂ and refrigeration of the solvent used in acid gas removal systems, and 50 KIW additional steam turbine and boiler capacity are required. [00463 From Figure 4, it can be seen that the yearly export of power is maximized ¹ during the peak price period &nά minimized during the ofφeak price period.

|0047j Therefore, the invention is well adapted 10 attain the ends and advantages mentioned as well ss those that are inherent therein, The particular embodiments disclosed above are illustrative only, as the invention may he modified and practiced in different but equivalent manners apparent to those having ordinary skill in the an and having the benefit of the teachings herein. While numerous changes may be made by those having ordinary .skill in the art. such changes are encompassed wiihm the spirit of this invention as defined by the appended claims. For example, while the use of a glycol chiller is discussed, any solvent heat exchange medium can be used to chill water from the cooling tower. Additionally, solvents such as Rectαsoi ^{i M} or amine solvents, e.g. methyl diethanol amine {MOfcA), can be used for acid gas removal. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed herein .may be altered or modified and ail such variations are considered within the scope and .spirit of the claimed invention. The terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.