US3719192A

US3719192A - Method and apparatus for transferring a comminuted solid from a low pressure into a space occupied by gas at high pressure

Info

Publication number: US3719192A
Application number: US00167687A
Authority: US
Inventors: A Squires
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-07-30
Filing date: 1971-07-30
Publication date: 1973-03-06
Anticipated expiration: 1990-03-06

Abstract

By the invention, a comminuted solid may be introduced into a space occupied by gas at high pressure with little expenditure of energy for compression of a gas. Solid is charged to a lock chamber at low pressure, and the top of the chamber is placed into communication with a first space filled with a gas at the high pressure. The solid is then dumped from the bottom of the chamber into a second space at high pressure. With the bottom of the chamber out of communication with this second space, but with the top still in communication with the aforementioned first space, a liquid is introduced into the bottom of the chamber to drive gas from the top and into the first space. When the lock chamber is filled with the liquid, the chamber is taken out of communication with the first space, and the liquid is drained from the chamber. The liquid may advantageously be water.

Description

United States Patent 1191 Squires March 6, 1973 METHOD AND APPARATUS FOR TRANSFERRING A COMMINUTED SOLID FROM A LOW PRESSURE INTO A SPACE OCCUPIED BY GAS AT HIGH PRESSURE [76] Inventor: Arthur M. Squires, 245 West 104th Street, New York, NY. 10025 [58] Field of Search .l37/l, 2,14,154, 572, 571, 137/575, 563, 209; 110/106; 302/29 [56] References Cited UNITED STATES PATENTS 2,232,198 2/1941 Ashworth v137/572 X 2,886,210 5/1959 Cooper 3,489,159 H1970 Chang ..137/57l X 3,232,494 2/1966 Poarch ..l37/575 X Primary Examiner-Alan Cohan [57] ABSTRACT By the invention, a comminuted solid may be introduced into a space occupied by gas at high pressure with little expenditure of energy for compression of a gas. Solid is charged to a lock chamber at low pressure, and the top of the chamber is placed into communication with a first space filled with a gas at the high pressure. The solid is then dumped from the bottom of the chamber into a second space at high pressure. With the bottom of the chamber out of communication with this second space, but with the top still in communication with the aforementioned first space, a liquid is introduced into the bottom of the chamber to drive gas from the top and into the first space. When the lock chamber is filled with the liquid, the chamber is taken out of communication with the first space, and the liquid is drained from the chamber. The liquid may advantageously be water.

15 Claims, 4 Drawing Figures SO0E65 F 10W l 054 P17555017! (7/4 1135 l w 0/? 502m Pkapurrs METHOD AND APPARATUS FOR TRANSFERRING A COMMINUTED SOLID FROM A LOW PRESSURE INTO A SPACE OCCUPIED BY GAS AT HIGH PRESSURE BACKGROUND OF THE INVENTION Interest is growing in operations which require introducing a comminuted solid into a space occupied by a gas at high pressure. A number of teams are currently at work on development of processes for gasifying, hydrogasifying, carbonizing, hydrocarbonizing, or otherwise treating coal at pressures ranging from a few hundred to several thousand pounds per square inch. Iron oxide ores may advantageously be reduced by hydrogen at an elevated pressure. A pulverulent solid may be conveyed pneumatically over long distances at low power consumption in a system operating at high pressure (see my US Pat. No. 3,268,264, issued Aug. 23, 1966). Solid waste may be burned at high pressure to provide hot gas to a gas turbine, or solid waste may be pyrolyzed at high pressure to useful gaseous products.

A disadvantage of conventional techniques for lockhoppering a solid into a space occupied by gas at high pressure arises from-the fact that, during the course of a lock-hoppering cycle, gas must be vented from the lock hopper. This is done in order to reduce its pressure from the high pressure at which a charge of solid is delivered from the hopper, and thereby to allow another charge of solid to be placed in the hopper at low pressure. The venting of gas results either in a serious consumption of power for its recompression or in a loss of power which might otherwise be generated if the gas were expanded in a turbine. Sometimes the amount of gas to be vented is reduced by placing the just-emptied hopper, still at high pressure, into communication with a second hopper just filled with a charge of solid at low pressure. My aforementioned Patent discloses an elaboration of this procedure, in which gas from the emptied hopper is vented in turn to a series of gas reservoirs to hold the gas in readiness for recompression from a series of intermediate pressure levels.

It has been recognized that the power required to deliver coal to a space occupied by gas a high pressure can be reduced if the coal is slurried with water, the slurry pumped to the high pressure, and the slurry heated in a furnace to turn the water into steam. See for example US. Pat. No. 2,735,265 (Feb. 21, 1956). A disadvantage of this procedure is that many coal-treating processes cannot use the mixture of steam and coal which results. Proposals have been made to separate the steam from the coal by a gas-solid separator, but it is difficult to obtain steam sufficiently free of dust for the steam to be useful. Proposals have also been made to slurry coal with a hydrocarbonaceous liquid, which would be vaporized by contacting the slurry with hot gaseous products of a coal-treating process. Such proposals suffer the disadvantage of a loss of heat in the gaseous products, since in general the hydrocarbonaceous vapor which results must be condensed from the products at too low a temperature for useful heat recoveries.

Proposals have been made to employ a lock-chamber fitted with a piston which drives gas at high pressure from the chamber either during or following the transfer of coal from the chamber. Present indications are that such a piston feeder will be expensive and may be unreliable; see the Report Engineering Study and Technical Evaluation of the Bituminous Coal Research, Inc. Two-Stage Super Pressure Gasification Process," prepared under Contract No. 14-32-0001- 1204 for the Office of Coal Research of the United States Department of Interior by Air Products and Chemicals, Inc. This Report reviewed the problem of transferring coal into a space occupied by a gas at high pressure, and concluded that additional approaches should be sought.

In light of the foregoing history of attempts to reduce the power required to deliver coal to a high pressure, I have been surprised to discover a simple procedure for practically eliminating the necessity to vent gas from a lock-chamber, the procedure embracing a step in which gas is displaced at high pressure from the lockc'hamber by pumping a liquid into the chamber.

SUMMARY OF THE INVENTION A primary object of the invention is to provide method and apparatus whereby a comminuted solid may be introduced into a space occupied by gas at high pressure with outstandingly low expenditure of power. The invention is useful for charging a solid to a solidtreating process which operates at high pressure and also to apparatus for conveying a solid by pneumatic means.

Another object of the invention is to provide means for raising a solid to high pressure with little expenditure of energy for compression of a gas.

According to the invention, there is provided an improved procedure for lock-hoppering a comminuted solid, pulverulent or lump-form, into a space occupied by a gas at high pressure. Solid is introduced into a chamber having a top and a bottom. The top of the chamber is put into communication with a first space occupied by a gas at elevated pressure. The solid is dumped from the bottom of the chamber into a second space occupied by a gas at elevated pressure. The bottom of the chamber is taken out of communication with the second space. A liquid is caused to enter the chamber thereby driving gas from the chamber at the top into the first space. The top of the chamber is taken out of communication with the first space, and liquid is withdrawn from the chamber.

The aforementioned liquid may advantageously be water.

Alternative procedures may be used for causing liquid to enter the chamber.

By one procedure liquid is withdrawn from a liquid reservoir maintained at low pressure and pumped into the chamber by a liquid pump. If this procedure is adopted, liquid withdrawn from the chamber may sometimes advantageously be returned to the liquid reservoir. Provision must be made for the chamber to become filled with a gas or vapor as the liquid is withdrawn from the chamber. A connection from the chamber to the atmosphere might be opened, for example. Alternatively, a source of another gas at low pressure might be provided. Another alternative would arise if the liquid is maintained at a temperature such that the equilibrium vapor pressure of the liquid is greater than the initial low pressure of the comminuted solid. The liquid could then be simply drained backed into the reservoir maintained at low pressure, a portion of the liquid flashing within the chamber to fill the chamber with vapor at the low pressure; or the vapor space of the reservoir could be placed into communication with the chamber so that vapor passes from the reservoir into the chamber as the liquid drains into the reservoir. The vapor filling the chamber after the liquid is drained therefrom would be vented before the next batch of solid is introduced into the chamber. Preferably, the low pressure of the liquid reservoir would be somewhat higher than the low pressure of the solid. Preferably, too, the solid would be heated to a temperature greater than the temperature at which the equilibrium vapor pressure of the liquid is equal to the low pressure of the solid. These arrangements would ensure that no vapor can condense upon the solid when it is added to the chamber.

An alternative procedure for causing liquid to enter the chamber dispenses with need for a liquid pump. A reservoir would be provided capable of holding liquid at the high pressure of the aforementioned first space. A source of vapor of the liquid at substantially this high pressure would be connected to the reservoir and the reservoir would be connected to the chamber after the transfer of solid to the aforementioned second space. Flow of vapor into the reservoir would cause the liquid to flow into the chamber. After the chamber has been taken out of communication with the first space, the source of vapor at high pressure may be connected with the chamber and the reservoir connected with a receiver for vapor at high pressure, to cause the liquid to leave the chamber and enter the reservoir. After the transfer of liquid from chamber to reservoir, the chamber would be filled with vapor at high pressure. It would be disconnected from the source of vapor at high pressure, and the vapor would be vented to low pressure. The solid would advantageously be heated to a temperature greater than the temperature at which the equilibrium vapor pressure of the liquid is equal to the low pressure of the solid.

Under the foregoing alternative, when vapor is vented from high pressure in the chamber to low pressure, the vapor may advantageously be put to use at one or more intermediate pressure levels. If water is chosen as the liquid, so that the vapor is steam, at least a portion of the steam vented from the chamber might be sent to equipment utilizing steam at one or more pressures intermediate between the high and low pressures. For example, the vented steam might be used to supply process heat, such as in reboiling a fractionation column, or the steam might be expanded in a turbine from one or more pressure levels, or the steam might be directed to one or more heaters of the regenerative type for boiler feed water.

BRIEF DESCRIPTION OF THE DRAWINGS The invention including various novel features will be more fully understood by reference to the accompanying drawings and the following description of the operation of the alternatives illustrated therein:

FIG. 1 is a schematic diagram illustrating the invention in a broad aspect.

FIG. 2 is a schematic diagram ofa preferred embodiment for introducing coal into a process treating coal at high pressure, the embodiment employing a liquid pump to introduce liquid at high pressure into a lock chamber.

FIG. 3 is a schematic diagram of an embodiment in which steam at high pressure is used to drive water from a reservoir into the lock chamber of the invention, and in which subsequently steam at high pressure is also used to return the water to the reservoir.

FIG. 4 is a schematic diagram illustrating how steam vented from the lock chamber of the invention under the embodiment of FIG. 3 may be utilized at regenerative heaters for boiler feed water.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference is now made to the schematic diagram of FIG. 1, which broadly illustrates myinvention. Comminution means 1 either crushes a solid to the form of lumps or crushes and grinds it to a powder. Optionally, drying means 2 are provided to dry the comminuted solid. The solid is transferred to bin 3 to await charging via line 4 to the top of lock chamber 5. The solid is transferred by gravity intermittently in batches from bin 3 to lock chamber 5 via line 4 and valve 6. Valve 6 is closed, and the solid is pressured within the chamber 5 by opening valve 7 bringing line 4 into communication with space 8, which is maintained at high pressure. With valve 7 remaining open, the solid is transferred by gravity from lock chamber 5 to space 9 via line 10 and valve 11. Space 9 is at substantially the same high pressure as space 8. Optionally,

spaces

8 and 9 may be interconnected or even be one and the same. After the solid is transferred to space 9, valve 11 is closed, and valve 12 is opened, allowing liquid to transfer from source 13 of liquid at high pressure into lock chamber 5. The liquid fills the chamber, driving gas from the chamber via open valve 7 into space 8 at high pressure. Valve 7 is then closed, and liquid is withdrawn from the chamber.

FIG. 1 illustrates alternative means for withdrawing liquid from chamber 5.

If the solid in bin 3 is at substantially atmospheric pressure and if the solid is compatible with atmospheric air, the liquid in chamber 5 may be depressured by opening optional valve 14 to the atmosphere. Liquid may then be drained from chamber 5 by opening optional valve 15, this valve communicating to a space at substantially atmospheric pressure or below.

Alternatively, optional valve 16 may be opened to optional source 17 of the vapor of the aforementioned liquid at a low pressure, which is equal to or greater than the low pressure of the solid in bin 3. Liquid may then be drained from chamber 5 by opening optional valve 15, this valve communicating to a space at substantially the low pressure of the aforementioned vapor from source 17.

A further alternate arises if the liquid in source 13 is maintained at a temperature such that its equilibrium vapor pressure is equal to or greater than the low pressure of the solid in bin 3. In this case, liquid may be drained from the chamber simply by opening optional valve 15 to a space at substantially the pressure corresponding to the equilibrium vapor pressure of liquid in source 13. Under this alternative, a portion of the liquid in chamber 5 flashes to form vapor, filling chamber 5 as the liquid drains from the chamber.

Under either of the last two alternatives, if the temperature ofliquid in source 13 is such that the equilibrium vapor pressure of liquid at this temperature is appreciably greater than the pressure in bin 3, a portion of the vapor standing in chamber 5 after liquid is drained therefrom may advantageously be vented via optional valve 14 before valve 6 is opened to introduce the next batch of solid into chamber 5.

A still further alternative for withdrawing liquid from lock chamber 5 is to open optional valve 16 to optional source 17 of vapor at substantially the high pressure of space 8. Liquid may then be drained from lock chamber 5 by opening valve 12, allowing vapor from optional source 17 to force liquid from chamber 5 into source 13. After the liquid has been transferred, valve 16 would be closed and optional valve 14 would be opened to vent vapor from chamber 5 to a low pressure.

Space 8 may sometimes advantageously be maintained at an appreciably higher pressure than space 9, to allow for a significant pressure drop through line 10. Such would be advantageous, for example, if the solid is to be lifted in line to a higher elevation, space 9 being placed above lock chamber 5; or, if the solid is to be conveyed an appreciable horizontal distance in line 10.

Turning attention to FIG. 2, I now describe a preferred embodiment for feed of coal to a process treating coal at high pressure. Concurrently, I give a numerical example of the operation of this embodiment for feed of 95,000 pounds per hour of dry coal from the atmosphere to a process treating coal at a pressure of about 650 pounds per square inch absolute (p.s.i.a.).

Comminution means 1 crushes and grinds coal to a fineness substantially smaller than 100 mesh (US. Standard). Drying means 2 rids the coal of water, and raises the coals temperature to a level of about 300 F. The hot, dry coal is transferred at atmospheric pressure to bin 3 to await charging via line 4 to the top of lock hopper 5, which has an effective internal volume of 222 cubic feet.

Coal is charged intermittently from bin 3 to lock chamber 5 via line 4 and valve 6. With valve 6 closed, the coal is pressured within chamber 5 to about 700 p.s.i.a. in a manner to be described subsequently. The pressurized coal is transferred from chamber 5 via line 10, valve 11, and line 21 to coal feed chamber 9, which has an effective volume of at least about 222 cubic feet, preferably greater.

Feed chamber 9 is maintained at a steady pressure of about 700 p.s.i.a., in a manner to be described, and coal flows continuously from chamber 9 to coal-treating process 22 via gently-curving lines 23. Two lines 23 are shown in FIG. 2, but more lines may sometimes be advantageously provided. To a degree, the rate of coal injection into coal-treating process 22 may be controlled by adjusting the pressure in feed chamber 9. A

more positive control is provided by using more or pressure coal passing from bin 3 to lock chamber 5. The remaining gas, about 1,022.0 moles per hour, is abstracted via line 25 from the gaseous discharge of process 22, carried from process 22 via outlet 26. The gaseous discharge in outlet 26 is at about 650 p.s.i.a. Net gas made by process 22 is delivered at this pressure via line 27, the pressure being regulated by valve 28. The gas abstracted via line 25 is heated or cooled, if necessary, in temperature-adjusting means 29 to bring its temperature to a level between about 300 and 600 F.

Coal ash or slag is delivered from process 22 via outlet 30. Liquid or solid product (if any) is delivered via outlet 31.

The function of the remaining equipment depicted in FIG. 2, as well as the manner in which lock chamber 5 is pressured and depressured, will best be understood from a step-by-step description of the operating cycle. I will begin the description at the point in the cycle where lock chamber 5 stands filled with about 9,500 pounds of coal and is in communication with bin 3 via open valve 6 and line 4, and also in communication with the atmosphere via open valve 14. Valves 7, l1, l2, 15, 32, 33, 34, and 35 are closed. Blower 36 boosts about 1,022.0 moles per hour of gas from temperatureadjusting means 29 to a pressure of about 700 p.s.i.a. and delivers this gas to surge vessel 8. Control means 37 governs the operation of blower 36 to maintain a pressure of about 700 p.s.i.a. in vessel 8 throughout the entire operating cycle. Check valve 38 is provided to prevent backflow of gas from vessel 8 through blower 36 should the blower fail. Vessel 8 is in communication via line 21 with the top of feed chamber 9; flow of gas from vessel 8 to chamber 9 maintains the pressure therein at about 700 p.s.i.a.

Step 1 of the operating cycle: Valves 6 and 14 are closed. Valve 33 is opened, allowing gas to flow from temperature-adjusting means 29 via line 4 into the top of lock chamber 5, thereby raising the pressure in chamber 5 to about 650 p.s.i.a. The gas in chamber 5 at the beginning of Step 1 amounts to about 0.22 moles. About 9.28 moles are transferred into chamber 5 during Step 1, raising the inventory of gas in chamber 5 to about 9.5 moles. Step 1 might be accomplished in about 1 minute, say.

Step 2: After lock chamber 5 reaches substantially 650 p.s.i.a. valve 33 is closed, and valve 7 is opened, thereby causing gas to flow from vessel 8 via line 4 into the top of lock chamber 5. About 0.73 moles of gas enters lock chamber 5, raising its pressure to about 700 p.s.i.a. and raising its gaseous inventory to about 10.23 moles. Step 2 might be accomplished in about 0.5 minute, say.

Step 3: After lock chamber 5 reaches substantially 700 p.s.i.a., valve 11 is opened, allowing the coal in chamber 5 to drop into feed chamber 9 via

lines

10 and 21. The transfer of the coal causes about 10.23 moles of gas to flow from feed chamber 9 into lock chamber 5, raising the inventory of gas in chamber 5 to'about 20.46 moles.

Step 4: When lock chamber 5 is emptied of coal, valve 11 is closed, and valve 12 is opened. Water pump 39 is then actuated, withdrawing water at about 250 F from vessel 40 and raising the waters pressure to about 700 p.s.i.a. The top of vessel 40 is in communication via line 41 and check valve 42 with source 43 of steam at about 30 p.s.i.a. As water is withdrawn from vessel 40, steam flows from source 43 into the top of vessel 40. Pump 39 delivers water at about 700 p.s.i.a. via check valve 44 and open valve 12 to line 10 and thence into the bottom of lock chamber 5. Water entering chamber drives gas outward at the top, the gas flowing via line 4 and open valve 7 to vessel 8 and feed chamber 9. Operation of pump 39 is continued until chamber 5 is substantially filled with water, control means 45 being advantageously provided to stop pump 39 when chamber 5 is full. Step 4 might be accomplished in about 3 minutes, say.

Step 5: When lock chamber 5 is filled with water at 700 p.s.i.a., valves 7 and 12 are closed.

Valves

32 and 15 are opened, thereby depressuring the water in lock chamber 5 and allowing this water to flow back into vessel 40 via line and open valve 15. As water leaves lock chamber 5, steam at about 30 p.s.i.a. enters the chamber, the steam being displaced from the upper part of vessel 33 and flowing to chamber 5 via line 41 and open valve 32.

Step 6: When lock chamber 5 is emptied of water, valves 32 and are closed, and valve 14 is opened, placing lock chamber 5 into communication with the atmosphere and reducing the pressure of the steam therein to atmospheric. Interior surfaces of chamber 5 and lines 4 and 10 are at substantially 250 F, and so depressuring chamber 5 to the atmosphere causes any liquid water which may cling to such surfaces to evaporate, leaving chamber 5 dry and ready to receive dry coal without danger of the coals becoming wet. Chamber 5 should be constructed in a manner such that the water can drain freely therefrom, without leaving substantialy pools of water behind, which by evaporating would cool off their surroundings to substantially the boiling temperature at the pressure of the atmosphere.

Step 7: When lock chamber 5 is at atmospheric pressure, valve 6 is opened, allowed coal to pass from bin 3 to chamber 5. At the end of Step 7, the system is again at the point in the cycle at which the foregoing description began.

To maintain the desired coal feed rate of 95,000 pounds per hour, the complete cycle should take 6 minutes. I

Valve 34 and line 46 are provided to permit addition of make-up water to vessel 40, as may be required to make good losses by evaporation from chamber 5 during step 6. Valve 35 and outlet 47 are provided to permit release of steam from vessel 40 when water is added thereto.

Pump 48 is provided to circulate water through water-heating means 49, as may be required to make good heat losses from the system and to maintain the desired temperature of 250 F in the water in vessel 40.

The power required for the foregoing numerical example of the described embodiment of the invention is appreciably less than the power needed for lock-hoppering of coal by conventional techniques. The exact saving of power depends upon the composition of the gaseous products in line 26 and upon the detailed procedures used in a conventional system for depressuring the coal lock hopper and in handling the lowpressure gas resulting therefrom. The power required for the foregoing example amounts to about 140 kilowatts, on the average. The power required for conventional lock-hoppering would be on the order of 400 kilowatts. The power for conventional lock-hoppering might be reduced to about 265 kilowatts by providing two lock chambers (like chamber 5) and by equalizing the pressure between the two chambers when one stands full of gas at 700 p.s.i.a. and the other stands filled with coal at atmospheric pressure.

The advantage of the instant invention is greater the higher the pressure of the process to be supplied with a solid. If the foregoing numerical example of the described embodiment were to be modified to supply coal at 1,500 p.s.i.a., the power would increase to about 250 kilowatts. Conventional lock-hoppering, with pressure equalization, would require on the order of6l 5 kilowatts.

Where a large coal feed rate must be handled, there would be an advantage in providing two or more lock chambers similar to chamber 5 of FIG. 2. Each lock chamber would communicate with bin 3 via a line like line 4 and a valve like valve 6. Each lock chamber would communicate with the atmosphere via a valve like valve 14; with line 41 via a valve like valve 32; with temperature-adjusting means 29 via a valve like valve 33; with vessel 8 via a valve like valve 7; with line 21 via a line like 10 and a valve like valve 11; with the top of vessel 40 via a valve like valve 15; and with the discharge of pump 39 via a valve like valve 12. In this modified arrangement, feed chamber 9 is advantageously several times larger in size than an individual lock chamber. In the modified arrangement, gas being displaced by water from one of the lock chambers like chamber 5 may be caused to flow into another of the lock chambers, as well as into vessel 8 or feed chamber 9.

Where the coal to be fed is in form of lumps,

equipment items

9, 23, and 24 may be omitted, and line 21 may discharge coal directly into a process vessel. Blower 36 and

items

7, 8, 37, and 38 may also sometimes be omitted if the coal is in form of lumps.

Reference is now made to the schematic diagram of FIG. 3, which illustrates an embodiment in which steam at high pressure is used to drive water from a reservoir into the lock chamber of the invention. Equipment items 1 through 11 operate in substantially the manner already described for the corresponding items in FIG. 1, and they need not be described again or discussed in detail. In the following description of FIG. 3, bin 3 is taken to be at atmospheric pressure, and the solid, in bin 3 is taken to be at 300 F, having been heated to this temperature in drying means 2. Consider the moment in the operation cycle where chamber 5 is empty of solid and stands in communication via open 7 with space 8 at high pressure.

Valves

11, 12, 14, 16, 51, 52, 56, and 59 are closed. Next, valve 51 is opened placing reservoir 53 in communication with source 54 of steam at high pressure. Reservoir 53 contains water at 250 F. Valve 12 is opened, and flow of steam from source 54 into the top of reservoir 53 causes water at high pressure to flow via valve 12 and line 10 into the bottom of lock chamber 5. This drives gas from lock chamber into space 8. As soon as lock chamber 5 is full of water, valves 7 and 51 are closed. Valve 16 is opened placing the top of lock chamber 5 into communication with source 54 of steam at high pressure. Valve 52 is opened, placing reservoir 53 into communication with equipment 55 for utilizing steam at high pressure. Flow of steam from source 54 into chamber 5 causes water to flow from chamber 5 via open valve 12 into the bottom of reservoir 53, and steam passes from the top of reservoir 53 via open valve 52 to equipment 55. When chamber 5 is empty,

valves

12, 16 and 52 are closed. Valve 56 is opened, venting steam in lock chamber 5 to equipment 57 utilizing steam at a lower pressure than the high pressure in space 8. After venting steam via valve 56 to the lowest pressure at which equipment 57 is capable of utilizing steam, valve 56 is closed, and steam in chamber 5 is vented to the atmosphere by opening valve 14. Temperature-adjusting means 58 are provided to maintain the temperature of the water at 250 F. Valve 59 is provided to add make-up water, as necessary, to reservoir 53 from line 60.

Equipment

55 or 57 may constitute, for example, a steam turbine or heat exchanger transferring latent heat of condensation of steam to a heat-receiving fluid or a chemical reactor for conducting a chemical change requiring an input of steam.

The schematic diagram of FIG. 4 illustrates an advantageous use for steam vented from chamber 5 of FIG. 3 through valve 56. In the example of FIG. 4, the vented steam is directed to three regenerative heaters for boiler feed water acting in cooperation with a steam turbine. High pressure steam enters steam turbine 71 from line 72, and is expanded in the turbine to a low pressure. Steam exhausts from the turbine to condenser 73. Condensate is pumped in pump 74 to heater 75, the first regenerative heater of boiler feed water in a train of such heaters. Three additional

regenerative heaters

76, 77, and 78 are depicted in FIG. 4. Heaters 75-78 are supplied with flows of steam extracted from steam turbine 71 through lines 79-82 respectively, and condensate is drained from the heaters via lines 83-86 respectively. Heater 78 operates at a steam pressure below the high pressure in space 8 of FIG. 3, and

heaters

77 and 76 operate at successively lower steam pressures. For example, if the high pressure in space 8 of FIG. 3 is 700 p.s.i.a., heater 78 suitably operates at 380 p.s.i.a.; heater 77 suitably operates at 175 p.s.i.a.; and heater 76 suitably operates at 80 p.s.i.a. When valve 56 is opened, check valve 87 opens automatically to pass steam to heater 78. When the pressure at valve 56 falls to the pressure of heater 78, check valve 87 closes automatically, and control means 88, sensing the closure of valve 87, opens valve 89. Check valve 90 then opens automatically to pass steam to heater 77. When the pressure at valve 56 falls to the pressure of heater 77, check valve 90 closes automatically, and control means 91, sensing the closure of valve 90, opens valve 92. Check valve 93 then opens automatically to pass steam to heater 76. After the pressure at valve 56 falls to the pressure of heater 92, valves 56 89, and 92 are closed, and the system of FIG. 4 stands ready to receive steam from the depressuring of lock chamber 5 in the next cycle of the solid-transfer operation.

I do not wish my invention to be limited to the particular embodiments and examples described.

The invention is useful for feeding solids other than coal. The reduction of iron oxide ores by hydrogen is advantageously conducted at elevated pressure, and such ores may be handled by the instant invention. Other examples could be given.

Although the invention is generally most useful for transferring solid from a source which is at substantially atmospheric pressure, e.g., bin 3 of FIGS. 1, 2 and 3, the invention may sometimes be advantageously used to transfer a solid supplied by a process operating at a vacuum or at an elevated pressure, the latter pressure being low in respect to the pressure in space 9 of FIGS. 1, 2, and 3.

In the claims, the term comminuted solid" will be understood to embrace both a pulverulent solid and a solid in form oflumps.

I claim:

1. A method useful for transferring a comminuted solid from a region of a relatively low pressure into a region occupied by a gas at a relatively high pressure, comprising:

a. introducing a quantity of a comminuted solid from a source of said solid at a low pressure into a chamber having a top and a bottom,

. placing said top of said chamber into communication with a first space occupied by a gas at a first elevated pressure,

c. placing said bottom of said chamber into communication with a second space occupied by a gas at a second elevated pressure not substantially greater than said first elevated pressure, thereby allowing substantially all of said quantity of solid to transfer from said chamber into said second space,

. taking said bottom of said chamber out of communication with said second space,

e. substantially filling said chamber with a liquid at substantially said first elevated pressure, thereby causing gas to leave said chamber at said top and to enter said first space,

f. taking said top of said chamber out of communication with said first space, and

g. removing said liquid from said chamber.

2. The method of claim 1 in which said liquid in step (e) is at a temperature sufficient that the equilibrium vapor pressure of said liquid is not less than said low pressure.

3. The method of claim 2 in which step (g) is accomplished by placing said chamber into communication with a source of the vapor of said liquid at said equilibrium vapor pressure, and

draining said liquid from said bottom of said chamber, thereby causing said vapor from said source to fill said chamber; and including the step of venting said vapor filling said chamber to said low pressure.

4. The method of claim 2 in which said solid is at a temperature greater than the temperature at which the equilibrium vapor pressure of said liquid is equal to said low pressure.

5. The method of claim 2 in which said liquid is water.

6. The method of claim 1 in which step (g) is accomplished by placing said chamber in communication with a source of gas at substantially said low pressure, and

draining said liquid from said bottom of said chamber, thereby causing said gas from said source to fill said chamber.

7. The method of claim 1 in which step (e) is accomplished by placing a supply of the vapor of said liquid into communication with a reservoir containing said liquid, said vapor having a pressure not substantially below said first elevated pressure,

placing said reservoir into communication with said chamber in a manner such that flow of vapor from said supply causes said liquid to flow from said reservoir into said chamber;

in which step (g) is accomplished by taking said supply of the vapor of said liquid out of communication with said reservoir.

placing said reservoir into communication with a receiver for vapor of said liquid,

placing said supply of the vapor of said liquid into communication with said chamber in a manner such that flow of vapor from said supply causes said liquid to How from said chamber to said reservoir, said vapor filling said chamber;

and including the steps of taking said chamber out of communication with said reservoir and said supply of the vapor of said liquid, and

venting said vapor filling said chamber to said low pressure.

8. The method of claim 7 in which said solid is at a temperature greater than the temperature at which the equilibrium vapor pressure of said liquid is equal to said low pressure.

9. The method of claim 7 in which said liquid is water.

10. The method of claim 9 in which said step of venting said vapor filling said chamber to said low pressure is conducted in a manner such that several successive portions of said vapor are vented in turn at successively lower pressures to the steam sides of a series of regenerative heaters for boiler feed water.

11. Apparatus useful for transferring a comminuted solid into a region occupied by a gas at high pressure, comprising:

a source of a comminuted solid at a low pressure;

a chamber having a top and a bottom;

means for introducing a quantity of said solid from said source into said chamber;

means for placing the top of said chamber into communication with a first space occupied by a gas at a first elevated pressure;

means for placing said bottom of said chamber into communication with a second space occupied by a gas at a second elevated pressure not substantially greater than said first elevated pressure and for causing substantially all of said quantity of solid to transfer from said chamber into said second space;

means for taking said bottom of said chamber out of communication with said second space;

means for regulating the. temperature of a liquid at a level sufficient that the equilibrium vapor pressure of said liquid is not less than said low pressure;

means for introducing said liquid into said chamber and for substantially filling said chamber with said liquid at substantially said first elevated pressure, thereby causing gas to leave said chamber at said top and to enter said first space;

means for taking said top of said chamber out of communication with said first space;

means for placing said top of said chamber into communication with a source of the vapor of said liquid at said equilibrium vapor pressure;

means for draining said liquid from said chamber, thereby causing said vapor of said liquid to enter said chamber from said source of said vapor;

means for taking said chamber out of communication with said source of said vapor; and

means for venting vapor from said chamber to said low pressure.

12. Apparatus of claim 1 l in which said means for introducing said liquid into said chamber include a vessel containing said liquid;

a pump;

a connection from the bottom of said vessel to said a connection for supplying liquid from said pump to said bottom of said chamber;

a connection for draining liquid from said chamber and for returning said drained liquid to said vessel; and in which said source of said vapor is the vapor space in said vessel, a connection being provided from said vapor space to said chamber.

13. Apparatus of claim 11 in which said liquid is water.

14. Apparatus useful for transferring a comminuted solid into a region occupied by a gas at high pressure, comprising:

a source of a comminuted solid at a low pressure;

a chamber having a top and a bottom;

means for regulating the temperature of a liquid at a level suf ficient that the equilibrium vapor pressure of said liquid is not less than said low pressure;

a source of the vapor of said liquid at a pressure not substantially below said first elevated pressure;

means for placing said source of said vapor into communication with a reservoir containing said liquid;

means for placing said reservoir into communication with said chamber in a manner such that flow of vapor from said supply causes said liquid to flow from said reservoir into said chamber, thereby causing gas to leave said chamber at said top and to enter said first space;

causes said liquid to flow from said chamber to said reservoir, said vapor filling said chamber;

means for taking said chamber out of communication with said reservoir and said source of the vapor of said liquid, and

means for venting said vapor filling said chamber to said low pressure.

15. Apparatus of claim 14 in which said liquid is water.

Claims

1. A method useful for transferring a comminuted solid from a region of a relatively low pressure into a region occupied by a gas at a relatively high pressure, comprising: a. introducing a quantity of a comminuted solid from a source of said solid at a low pressure into a chamber having a top and a bottom, b. placing said top of said chamber into communication with a first space occupied by a gas at a first elevated pressure, c. placing said bottom of said chamber into communication with a second space occupied by a gas at a second elevated pressure not substantially greater than said first elevated pressure, thereby allowing substantially all of said quantity of solid to transfer from said chamber into said second space, d. taking said bottom of said chamber out of communication with said second space, e. substantially filling said chamber with a liquid at substantially said first elevated pressure, thereby causing gas to leave said chamber at said top and to enter said first space, f. taking said top of said chamber out of communication with said first space, and g. removing said liquid from said chamber.

3. The method of claim 2 in which step (g) is accomplished by placing said chamber into communication with a source of the vapor of said liquid at said equilibrium vapor pressure, and draining said liquid from said bottom of said chamber, thereby causing said vapor from said source to fill said chamber; and including the step of venting said vapor filling said chamber to said low pressure.

5. The method of claim 2 in which said liquid is water.

6. The method of claim 1 in which step (g) is accomplished by placing said chamber in communication with a source of gas at substantially said low pressure, and draining said liquid from said bottom of said chamber, thereby causing said gas from said source to fill said chamber.

7. The method of claim 1 in which step (e) is accomplished by placing a supply of the vapor of said liquid into communication with a reservoir containing said liquid, said vapor having a pressure not substantially below said first elevated pressure, placing said reservoir into communication with said chamber in a manner such that flow of vapor from said supply causes said liquid to flow from said reservoir into said chamber; in which step (g) is accomplished by taking said supply of the vapor of said liquid out of communication with said reservoir. placing said reservoir into communication with a receiver for vapor of said liquid, placing said supply of the vapor of said liquid into communication with said chamber in a manner such that flow of vapor from said supply causes said liquid to flow from said chamber to said reservoir, said vapor filling said chamber; and including the steps of taking said chamber out of communication with said reservoir and said supply of the vapor of said liquid, and venting said vapor filling said chamber to said low pressure.

9. The method of claim 7 in which said liquid is water.

11. Apparatus useful for transferring a comminuted solid into a region occupied by a gas at high pressure, comprising: a source of a comminuted solid at a low pressure; a chamber having a top and a bottom; means for introducing a quantity of said solid from said source into said chamber; means for placing the top of said chamber into communication with a first space occupied by a gas at a first elevated pressure; means for placing said bottom of said chamber into communication with a second space occupied by a gas at a second elevated pressure not substantially greater than said first elevated pressure and for causing substantially all of said quantity of solid to transfer from said chamber into said second space; means for taking said bottom of said chamber out of communication with said second space; means for regulating the temperature of a liquid at a level sufficient that the equilibrium vapor pressure of said liquid is not less than said low pressure; means for introducing said liquid into said chamber and for substantially filling said chamber with said liquid at substantially said first elevated pressure, thereby causing gas to leave said chamber at said top and to enter said first space; means for taking said top of said chamber out of communication with said first space; means for placing said top of said chamber into communication with a source of the vapor of said liquid at said equilibrium vapor pressure; means for draining said liquid from said chamber, thereby causing said vapor of said liquid to enter said chamber from said source of said vapor; means for taking said chamber out of communication with said source of said vapor; and means for venting vapor from said chamber to said low pressure.

12. Apparatus of claim 11 in which said means for introducing said liquid into said chamber include a vessel containing said liquid; a pump; a connection from the bottom of said vessel to said pump; a connection for supplying liquid from said pump to said bottom of said chamber; a connection for draining liquid from said chamber and for returning said drained liquid to said vessel; and in which said source of said vapor is the vapor space in said vessel, a connection being provided from said vapor space to said chamber.

13. Apparatus of claim 11 in which said liquid is water.

14. Apparatus useful for transferring a comminuted solid into a region occupied by a gas at high pressure, comprising: a source of a comminuted solid at a low pressure; a chamber having a top and a bottom; means for introducing a quantity of said solid from said source into said chamber; means for placing the top of said chamber into communication with a first space occupied by a gas at a first elevated pressure; means for placing said bottom of said chamber into communication with a second space occupied by a gas at a second elevated pressure not substantially greater than said first elevated pressure and for causing substantially all of said quantity of solid to transfer from said chamber into said second space; means for taking said bottom of said chamber out of communication with said second space; means for regulating the temperature of a liquid at a level sufficient that the equilibrium vapor pressure of said liquid is not less than said low pressure; a source of the vapor of said liquid at a pressure not substantially below said first elevated pressure; means for placing said source of said vapor into communication with a reservoir containing said liquid; means for placing said reservoir into communication with said chamber in a manner such that flow of vapor from said supply causes said liquid to Flow from said reservoir into said chamber, thereby causing gas to leave said chamber at said top and to enter said first space; means for taking said top of said chamber out of communication with said first space; means for taking said source of said vapor out of communication with said reservoir; a receiver for vapor of said liquid; means for placing said reservoir into communication with said receiver; means for placing said source of the vapor of said liquid into communication with said chamber in a manner such that flow of vapor from said source causes said liquid to flow from said chamber to said reservoir, said vapor filling said chamber; means for taking said chamber out of communication with said reservoir and said source of the vapor of said liquid, and means for venting said vapor filling said chamber to said low pressure.