HK1172287A - Efficient methods for operation with high pressure liquids - Google Patents

Description

Efficient method for operating with high pressure liquid

Cross Reference to Related Applications

This application claims priority from U.S. provisional patent application 61/161,977, filed 3/20/2009, the contents of which are incorporated herein by reference.

Background

The invention relates to the following method: these methods are used to more efficiently perform various high pressure operations or operations with high pressure liquids such as those containing pressure precipitation, control high temperature operations by cooling high pressure liquid streams, and efficiently supply and use liquids from the subterranean space.

Since the cost of electricity used to drive pumps to pressurize fluids is steadily increasing worldwide, it is important to investigate whether operating methods involving high pressure fluids can be performed more efficiently to conserve such expensive electrical energy. It has been found that there are a number of operations involving the use of high pressure liquids that can be significantly altered to allow these operations to be performed more efficiently.

Disclosure of Invention

It has been found that various processes and/or treatments involving such high pressure liquids can be more efficiently performed by carefully conserving the high pressure energy present in the high pressure liquid. The key to such conservation was found to be the use of an energy recovery device that is capable of transferring high pressure from one stream to another without consuming the pressure of the high pressure stream.

In one particular aspect, the present invention provides a method for efficiently achieving high pressure precipitation, the method comprising the steps of:

(a) a feed stream with dissolved solute or colloidal suspension is supplied,

(b) raising the pressure of said feed stream to at least about 500psi (35bar),

(c) passing said high pressure liquid stream of step (b) to a reactor,

(d) treating the high pressure liquid stream in the reactor to cause a precipitate to form,

(e) withdrawing a solute depleted or colloidal suspension depleted liquid stream from said reactor while effecting step (a) by exchanging said high pressure of said liquid stream being withdrawn with a feed stream supplied in step (a)

(b) To maintain a high pressure therein, and

(f) separating the precipitate from the high pressure liquid.

In another particular aspect, the invention provides a method of efficiently delivering water to an underground mine and recovering the water to the surface, the method comprising the steps of:

a source of liquid is provided,

effecting gravity flow of a downflow of said liquid into a mine, which is at least 1000 feet (305 meters) down and which requires cooling,

reducing the pressure of the liquid stream to about atmospheric pressure,

in a mine, using the atmospheric pressure fluid stream,

increasing the pressure of the used liquid stream by exchanging the pressure of the used liquid stream with the pressure of the downward flowing liquid stream, an

Returning the repressurized used fluid stream to the surface.

In yet another particular aspect, the present invention provides a method for efficiently regulating the temperature of a high pressure liquid stream, the method comprising the steps of:

providing a first high pressure liquid stream at least about 500psi (34bar), the first high pressure liquid stream desirably being heated or cooled while maintaining substantially the same pressure,

flowing the first, higher temperature liquid stream through a heat exchanger designed for low pressure operation, wherein the heat exchanger either (1) rejects heat directly to a cooler fluid to cool the first liquid stream and produce a second, cooler liquid stream having a temperature that is at least reduced by about 50 ° F (10 ℃), or (2) absorbs heat from a warmer fluid to heat the first liquid stream and produce a second, warmer liquid stream having a temperature that is at least increased by about 50 ° F (10 ℃),

exchanging the high pressure of said first liquid stream with a second liquid stream flowing from a heat exchanger prior to said first liquid stream entering said heat exchanger to produce a depressurized first liquid stream and a pressurized second liquid stream, and

returning said pressurized second liquid stream to said reactor at about the pressure at which said first liquid stream exits.

Drawings

Fig. 1 is a schematic diagram illustrating a method for efficiently performing chemical and/or object reactions at high pressures.

Fig. 2 is a schematic diagram illustrating a method for efficiently using a flow of surface water in an underground space such as a working mine, for example, to efficiently cool an environment.

FIG. 3 is a schematic diagram illustrating a method for efficiently cooling a high temperature liquid stream to lower the temperature of the liquid stream while maintaining substantially the same pressure in the liquid stream, for example, to control an exothermic chemical process.

Detailed Description

Various chemical and/or physical treatments are known to exist that operate more efficiently at superatmospheric pressures, such as at least about 500psi (35bar), and particularly at pressures above about 800psi (55 bar). For purposes of this application, pressure should be understood to mean "gauge" pressure, i.e., a pressure value above atmospheric pressure, unless otherwise specified. Some of these operations involve protein processing, while others involve precipitation of metals from a liquid stream containing dissolved solutes or colloidal suspensions. For example, in the protein field, it is advantageous to treat the dissolution of insulin and albumin in organic solutions at high pressures, such as 1000-. It is also known to treat an aqueous solution of whey with carbon dioxide under high pressure to fractionate and cause precipitation of whey proteins. There are various treatments of solutions of metal ions that can be effectively precipitated under pressure by treatment with hydrogen and/or sulfur containing gases using a technique generally referred to as pressure precipitation. It is also known to treat colloidal suspensions of minerals or other raw materials with acids or the like to precipitate metals under a technique known as pressure leaching.

FIG. 1 is a schematic diagram of an exemplary operation of a pressure precipitation. A vessel 11 of liquid is shown for feeding to a low pressure feed pump 13 at atmospheric pressure. The discharge from the feed pump is separated and is first used to feed a small high-pressure pump 15, which small high-pressure pump 15 is used to deliver liquid to the inlet 17 of the reactor 19, so that the reactor is filled with high-pressure liquid in the situation where the treatment takes place. The reactants are optionally fed to reactor 19 via line 21 and may include carbon dioxide at super-atmospheric pressure. Once the treatment has been sufficiently carried out for effective precipitation, the liquid stream is discharged through the outlet line 23 and can optionally be conveyed to a separator 25, where at the separator 25 the particulate precipitate can be removed while the liquid stream is under high pressure. Examples of such processes include those in U.S. Pat. Nos. 5,925,737 and 6,562,952.

As shown in fig. 1, the high pressure liquid stream from reactor 19 is fed to an input line 27 which enters the right hand end of an energy recovery unit 29. While a rotary energy recovery unit such as the one shown in U.S. patent nos. 5,338,158 and 6,659,731 would be preferred, other types of such isobaric devices known in the art, such as the Dweer energy recovery device sold by CalderAG, for example, could also be used. The low pressure pump 13 also supplies a low pressure feed stream to an inlet 31 at the opposite end of the energy recovery unit 29. The preferred energy recovery unit will operate without any auxiliary motor drive and will transfer the pressure of the high pressure effluent stream exiting the reactor to the feed stream fed to inlet 31 by low pressure pump 13. Due to this transfer, the high pressure feed stream exits the outlet 33 at the left hand end of the unit 29 at a pressure of, for example, about 97% of the pressure of the stream exiting the reactor 19. The circulation pump 35 draws the liquid exiting the energy recovery unit and overcomes the line losses when feeding this liquid stream to the inflow 17 of the reactor. As long as the system is operating, substantially the entire treated stream is pressurized by the energy recovery unit 29 and the high pressure pump 15 is rarely, if ever, operated. The liquid stream flowing out of the reactor and transferring its high pressure in the energy recovery unit 29 flows out via an outlet 37 at the right-hand end of the unit and can optionally be fed to a separator 39, especially if no separator is included in the line between the reactor 19 and the energy recovery unit 29. For some processes, the particulate precipitate separates as particulates while the effluent stream is at high pressure; in other processes, however, it is more efficient to separate the precipitate with a pressure reduction. Depending on the treatment, the disposal of the waste liquid from the optional separator 39 may be partly returned as a recycle stream 41 to the container 11 of the feed liquid, or may be entirely directed through a line 43 leading to a further treatment step.

An exemplary operation for effectively cooling an underground space that may have a temperature that rises above a comfortable level and requires cooling due to geothermal heat at a significant distance underground, for example, about 1000 feet (305 meters), and heat generated by electric motors and the like, is schematically illustrated in fig. 2. Furthermore, there is a need for water in underground mines, for example for washing, cleaning and the like, wherein it is also necessary to return the used water flow to the surface. The cooling of the underground space can be effectively performed, for example, by the supply of a cooling water flow which is pumped to an operating underground mine 49 via a simple low pressure pump 45, while the low pressure pump 45 supplies a down flow line 47 which leads downwards approximately 2300 feet (750 meters). Before the coolant flow is supplied to the heat exchanger 51, which coolant flow is supplied to the high pressure inlet 53 of the energy recovery unit 55 similarly as described above, the heat exchanger 51 is for example a heat exchanger with a large surface area through which the atmosphere at the appropriate level of the mine is circulated. In this unit, the pressure may be reduced from about 750psi (52bar) to about atmospheric pressure; and then fed from the low pressure discharge 57 of the unit to the heat exchanger 51. The heat exchanger 51 can be manufactured at much lower cost since it need not be constructed to contain and operate with high pressure liquid, and can have higher efficiency due to the superior heat transfer achieved through the much thinner walls. The heated liquid effluent stream 59 from the heat exchanger 51 is then returned to the opposite end of the energy transfer unit 55 where it enters through a low pressure inlet 61 and its pressure rises back to near the pressure of the descending stream entering the inlet tube 53 at the left hand end of the unit. Since there will be some small amount of lubricant leakage from the high pressure liquid passing through the unit 55, a small jet pump 63 is provided to accommodate the slight additional volume of low pressure liquid by bypassing the energy recovery unit as shown. In this way, about 97% of the pressure of the descending liquid stream is recovered, which is sufficient to return the now warm liquid to the surface. Line losses in the down-flow and up-flow lines of about 90psi (6bar) can be conveniently overcome by the pressure supplied by the surface pump 45. The line losses can instead be compensated for by means of a suction pump 65 in the up-flow line, which suction pump can conveniently be located at the surface.

A study of the entire procedure showed that: by this entire method, an efficient use of cooling or cleaning liquid in the underground space is achieved extremely economically. It is advantageous to utilize the gravity flow of surface liquid flowing down to the level of the working mine, wherein this gravity flow is most efficiently used for absorbing heat from the atmosphere in the low pressure heat exchanger device, which can be achieved by reducing its pressure fundamentally, or for other operational purposes. It is important that such pressure reduction to facilitate the use of the low pressure heat exchanger device is done in such a way that almost all the energy required for returning the used liquid flow to the surface due to the strategic arrangement of such energy recovery device can be supplied. Since the surface and jet pumps 63 only spend a minimum amount of energy, it can be seen that the overall situation is a highly advantageous situation, especially when using an energy recovery unit that does not require an auxiliary power system. For example, extremely efficient cooling of underground installations is provided simply by feeding a flow of coolant through an access point at the surface level and driving a surface pump 45 to feed approximately 1% of the head pressure required to return the flow to the surface.

Figure 3 schematically illustrates high pressure processing which is carried out in a reactor 71 or the like fed by an inlet stream 73. This treatment consists in the need to let the temperature of the liquid material drop instead of the pressure. One such example is chemical processing which is highly exothermic in nature, requiring cooling to keep the reaction under control. For other processes that absorb heat, heat supply is required instead. While various cooling or heating methods may be used, FIG. 3 illustrates a particularly economical arrangement that uses a low pressure heat exchanger 75 of the type just described above. This both saves capital costs and provides for more efficient heat exchange. A cooling application is described in which a substream 77 of the high pressure, high temperature liquid is withdrawn from the main process vessel 71 through an outlet and is delivered to a high pressure inlet 79 into an energy recovery unit 81. These units are configured to: so that the inflow and outflow of the liquid flow effectively drives the pressure exchange, whereby no external power supply is required. Furthermore, there is no significant pressure drop in line 77 exiting processor 71, thereby maintaining the desired high pressure in the process chamber and avoiding any consumption thereof. In the energy recovery unit 81, the pressure of the high temperature substream is transferred to the stream entering the opposite end of the unit, thereby reducing the pressure of the substream substantially to that of the stream entering the other end. For example, a high temperature liquid stream flowing from the main vessel 71 at about 1000psi (69bar) can have its pressure reduced to a pressure just above atmospheric pressure in an outlet 83 of the unit 81, e.g. about 10psi (0.7bar), which outlet 83 leads to the low pressure heat exchanger 75. Such a high surface area heat exchanger can be economically configured to handle relatively low pressure liquids and can effectively reduce the temperature of the liquid stream from, for example, about 400 ° f (204 ℃) to about 100 ° f (38 ℃) using heat exchange with the atmosphere or any other available gas or liquid, depending on the heat exchanger design. It is understood that for heating applications, a suitable temperature rise of at least about 50 ° f (10 ℃) is effectively achieved; while a higher temperature rise leads to higher economics. The discharge line 85 of the heat exchanger is connected to a low pressure inlet conduit 87 at the other end of the energy recovery unit 81. A small pump 89 is preferably included in the line to compensate for line losses through the heat exchanger.

In the energy recovery unit 81, the now cooled liquid stream pressure is returned to a value equal to about 97% of the pressure of the initial high temperature discharge stream 77 from the vessel 71 flowing into the inlet conduit 79. The high pressure outlet 91 of the rotary energy recovery unit 81 is connected to the side inlet of the main vessel 71 to return a stream of liquid to the main vessel and a circulation pump 93 is provided in this line 95 to draw off the fluid discharged from the energy recovery unit and to convey this return stream to the main vessel where the returned cooled substream mixes with the liquid in the vessel and desired temperature control is achieved. A small pump 97 is also included to accommodate oil leakage from the high pressure side of the unit 81. A high pressure discharge stream 99 exits the vessel 71 at about the desired target temperature.

In summary, it can be seen that such an arrangement provides an extremely efficient way to economically and efficiently maintain a desired reaction temperature in a reaction zone, or simply to significantly reduce the temperature of a production stream while maintaining the production stream at a high pressure, as the production stream is passed to the next point in the overall operation. Economy is achieved not only by using a low pressure heat exchanger with far lower capital cost and greater operating efficiency, but also by minimizing the pumping power required to achieve such desired cooling.

While the invention has been described with reference to certain preferred embodiments, it will be understood that various changes and modifications as would be obvious to one skilled in the art may be made without departing from the scope of the invention, which is set forth in the following claims.

Claims (20)

1. A method for efficiently achieving high pressure precipitation, the method comprising the steps of:

(a) a feed stream with dissolved solute or colloidal suspension is supplied,

(b) raising the pressure of said feed stream to at least about 500psi (35bar),

(c) passing said high pressure liquid stream of step (b) to a reactor,

(d) treating the high pressure liquid stream in the reactor to cause a precipitate to form,

(e) withdrawing a solute depleted or colloidal suspension depleted liquid stream from the reactor while maintaining a high pressure therein by exchanging the high pressure of the withdrawn liquid stream with the feed stream supplied in step (a) to achieve a majority of the pressurization in step (b), and

(f) separating the precipitate from the high pressure liquid.

2. The method of claim 1, wherein the separating is performed prior to the pressure exchanging.

3. The method of claim 1, wherein the separating is performed after the pressure exchanging.

4. The method according to any one of claims 1-3, wherein the pressure exchange is effected in an isobaric rotary pressure exchange unit.

5. The method of any one of claims 1-3, wherein the feed stream has solubilized protein.

6. The method of claim 5, wherein the high pressure liquid stream is treated with carbon dioxide in the reactor to cause a precipitate to form.

7. The method of claim 6, wherein the pressure exchange is effected in an isobaric rotary pressure exchange unit.

8. The method of any one of claims 1-3, wherein the feed stream comprises metal ions.

9. The method of claim 8, wherein the high pressure liquid stream is treated with a sulfur-containing compound in the reactor, which results in the formation of insoluble metal sulfides.

10. The method of claim 9, wherein the pressure exchange is effected in an isobaric rotary pressure exchange unit.

11. A method of efficiently delivering water to an underground mine and recovering the water to the surface, the method comprising the steps of:

a source of liquid is provided,

effecting a downflow gravity flow of the liquid into a mine, the mine being at least 1000 feet (305 meters) or less and requiring cooling,

reducing the pressure of the liquid stream to about atmospheric pressure,

in the mine, using the atmospheric pressure fluid stream,

increasing the pressure of the used liquid stream by exchanging the pressure of the used liquid stream with the pressure of the downward flowing liquid stream, an

Returning the repressurized used fluid stream to the surface.

12. The method of claim 11 wherein the reduced pressure liquid stream exiting the pressure exchange step is caused to flow through a low pressure heat exchanger in which the temperature of the liquid stream rises at least about 100 ° f (38 ℃) to produce a heated liquid stream, which is then repressurized and returned to the surface.

13. A method according to claim 11 or 12, wherein the first liquid is used at atmospheric pressure during the cleaning operation to produce the used liquid stream.

14. The method of claim 11 or 12, wherein the pressure exchange is effected in an isobaric rotary energy recovery unit.

15. A method for efficiently regulating the temperature of a high pressure liquid stream, said method comprising the steps of:

providing a first high pressure liquid stream at least about 500psi (34bar), said first high pressure liquid stream desirably being heated or cooled while maintaining substantially the same pressure,

flowing the first high temperature liquid stream through a heat exchanger designed for low pressure operation, wherein the heat exchanger either (1) rejects heat directly to a cooler fluid to cool the first liquid stream and produce a second cooler liquid stream having a temperature that is at least reduced by about 50 ° F (10 ℃), or (2) absorbs heat from a warmer fluid to heat the first liquid stream and produce a second warmer liquid stream having a temperature that is at least increased by about 50 ° F (10 ℃),

exchanging the high pressure of said first liquid stream with said second liquid stream exiting said heat exchanger prior to said first liquid stream entering said heat exchanger to produce a depressurized first liquid stream and a repressurized second liquid stream, and

returning the repressurized second stream to the reactor at about the pressure of the first stream as it exits.

16. The process of claim 15 wherein said first high pressure liquid stream is withdrawn from a process reactor and said second liquid stream is returned to said process reactor.

17. The method of claim 15 or 16, wherein the temperature of the first high pressure liquid stream is reduced.

18. The method of claim 17, wherein the pressure exchange is effected in an isobaric rotary energy recovery unit.

19. The method of claim 15 or 16, wherein the temperature of the first high pressure liquid stream is increased.

20. The method of claim 19, wherein the pressure exchange is effected in an isobaric rotary energy recovery unit.