US2712730A

US2712730A - Method of and apparatus for storing gases

Info

Publication number: US2712730A
Application number: US250898A
Authority: US
Inventors: Carl V Spangler
Original assignee: JF Pritchard and Co
Current assignee: JF Pritchard and Co
Priority date: 1951-10-11
Filing date: 1951-10-11
Publication date: 1955-07-12
Anticipated expiration: 1972-07-12

Description

July 12, 1955 c. v. SPANGLER l 2,712,736

METHOD OF AND APPARATUS FOR STORING GASES Filed Oct. 11. 1951 nnentor Cof/ V. fpafgy/ef @MYV/@MM Gttomegs United tates Patent ME'IGD 0F AND APPARATUS FR STORING GASES Pittsburgh, Pa., assigner to J. F.

Carl V. Spangler,

Kansas City, Mo., a corporation of Pritchard & Co., Missouri This invention relates to a method of and apparatus for storing or stock piling of gases, for example, hydrocarbon gases such as propane, methane or natural gas such as the commercial pipe line gas which is now distributed on almost a nation-wide basis, the present application being an improvement on the method and apparatus disclosed in my co-pending application led May i4, 1949, Serial No. 93,384, now Patent No. 2,663,626.

The principal object of the invention is the provision of a practical, safe and economical storage of the above mentioned gases through adsorption by a solid adsorbent material at moderate pressures and at a temperature close to, at the liquefaction temperature of methane at the storage pressure.

it is also an object of the invention to provide for release or" the adsorbed gas when the gas is desired for use or to augment the flow volume in a pipe line at times of high demand.

In accomplishing these and other objects of the invention hereinafter described, I have provided an improved method and apparatus which is diagrammatically illustrated in the accompanying drawing wherein:

1 designates a pipe line leading from a supply of natural gas, for example, a commercial high pressure gas transportation system by which natural gas is conveyed from a lield of production to a market which may be many miles from the source of supply. Protable operation of such systems depend upon substantially full pipe line flow. Consequently, during times' of low demand for the gas, adequate storage must be provided for the surplus gas which is made available for augmenting the pipe line flow during times of high market demand. This storage gas may be taken at the start of the transportation system and at various points along the length of the line where it is convenient to remove and store the gas. It is therefore to be understood that the pipe line 1 merely connects a source for the gas to be stored in accordance with the present invention. It is also to be understood that such gas is substantially methane although pipe line gas in addition to normal impurities may contain carbon dioxide, nitrogen, traces of the rare gases such as helium, argon, etc., limited amounts of vapor or gas of the heavier hydrocarbons such as ethane, propane, butaues, pentanes, etc. which are not removed from it completely in commercial practice. Essentially, however, the major ow is methane and therefore in the present description the terms methane and natural gas are used synonomously.

I have discovered that methane can be adsorbed as an adsorbate on adsorbent materials at temperatures near its liqueiaction temperature in suliicient amounts to make such storage system commercially practical.

ln carrying out the invention the gas to be stored is brought from the line l into the storage system through an orifice meter indicated at 2 and passed through a puriiication plant 3 in which all traces of vapor phase moisture is removed from the gas together with any possible carbon dioxide, hydrogen sulde, or other acid 4gases 2,712,730 ce Patented July 12, 1955 which may be mixed in the main gas supply as impurities.

After purification the gas passes through a pipe 4 to a compressor 5 from which the gas is conducted through a pipe 6 to an aftercooler 7 and then through a pipe 8 to a heat exchanger 9 in which the gas is prechilled prior to discharge through a pipe 10 to a refrigerating apparatus 11. The refrigeration apparatus may be of any suitable type and utilize various methods of refrigeration depending upon the individual situation. The temperature of the gas as it leaves the refrigerated apparatus will be just above the liquefaction temperature of the methane at the operating pressure. The refrigerated gas is then conducted through a pipe l2 to a separator 13 wherein those materials which have been liquefied or solidified are separated from gas stream. The liquid so removed will be through a pipe 14 to a separate outside storage system (not shown) and will not enter into any processing embodying the present invention, except as the refrigeration embodied in this cold liquid may be used for precooling entering natural gas. The vapor phase methane that is left in the system is conducted through a pipe l5 into a condenser 16 wherein further heat removal from the methane causes it to condense. The refrigeration system used in the condenser 16 may be any of several systems well known in the art of gas liquefacfrom the condenser 9 wherein the methane vapors serve to cool incoming methane. The methane vapors are then conducted and discharged through a pipe 21 to the suction of the gas compressor 5 by way of a pipe 22 connecting the pipes 21 with the pipe 4. By continual ow of liquid methane into the adsorbent 19, the adsorbent will eventually reach temperatures closely approaching the temperature of the liquid methane. When the adsorbent has been cooled to temperatures slightly above the temperature of liquid methane, methane will be adsorbed in the pores of the adsorbent and the liquid methane phase will disappear except for a possible slight visible wetting of the adsorbent.

As methane is adsorbed on the adsorbent, fresh gas will be brought into the plant from line 1 to maintain the volume of the circulating system substantially constant. When the adsorbent is saturated with methane need be removed. It

However, the quantities of gas which must be circulated are extremely large, furthermore, if gas circulation is used there is a temperature gradient through the adsorbent which reduces its capacity to adsorb gas below the value obtained if the entire bed is'cooled to. a temperature closely approaching the liquefaction temperature.

they may be comprised of bottom 24 and a top 25 constructed with substantially tight joints to prevent direct leakage into and out of the Vessel. The vessel is completely insulated preferably' is l.supplied by the container. ln some cases ,nected to the discharge pipe Ztl.

by lining all the interior surfaces with an insulating material 26 suiiicient to maintain the desired low temperature oiV the adsorbent. With this method of insulation, the walls of the vessel are protected from becoming iriable and structurally unsafe at the extremely low ternperatures involved. Therefore, special expensive alloys and construction are not required as in cases Where the metal is indirect Contact with low temperatures. in fact, such tanks as now used for large oil or gas storage might be used with modifications for handling tie Inaterials herein involved. lt is important, however, that the thickness and nature of the insulating material be selected as the best available for the duty. Suitable insulating materials are readily obtained which have adequate strength, thermal capacities and general physical and `chemical qualications for the duty described. lt is also desirable to select an insulation that is resistant to abrasion by the adsorbing material. Such materials need only protection from the weather, which function it may be desirable to install an inner liner 27 of thin sheet metal or other material between the insulation and the adsorbent bed to prevent large circulating `currents. of gas from reaching the outer vessel wall or to prevent the flow of liquid through the insulation.

The liquid from the condenser is discharged onto the adsorbent through a distribution system which in the illustrated instance comprises a header 2d which connects the inlet pipe with a plurality of distribution ducts 29 having perrorations through which the liquid methane is distributed substantially uniformly over the horizontal cross sectional area of the vessel.

A similar collection system of perforate ducts E@ is located at the bottom of the bed of adsorbent and con- The distributing and discharge systems are formed of a suitable material to withstand the temperatures involved. Since Vthe distributing and discharge systems are cooled by the gas or liquid passing therethrough, insulating seals 3l areV required where the pipes pass through the walls or the vessel. A second compressor 32 is shown in connection with the pipes t and i5 through intalce and

discharge pipes

33 and 34.

Filling the space within the vessel Vis the body of solid adsorbent material 19. The adsorbent material may be Vallowed to rest directly on the insulating material on the bottom of the vessel and to hll out against the sides. ln turn the insulation across the top oi the vessel and above the adsorbent material may rest directly on the bed of adsorbent. In order to take advantage of possible physical characteristics of either insulation or adsorbent material, structural props or supports might be supplied if needed to take or distribute some of tre stress.

The adsorbent 1% may comprise one or a mixture o two or more of the well-known adsorbent materials .such as an adsorbent clay, attapulgite, ullers earth, activated carbons and charcoals, bauKites, sintomas, calcium sulfate, silica or alumina gels, diatomaceous earth, etc. These materials are all solids and may be prepared for use in a variety of ways.

When it becomes necessary and desirable to use the gas in storage, a warm methane or natural gas is circulated in suitable quantity by the compressor 32 through thel

pipes

33 and 34 to the condenser 16 which is now used as a heater to increase the temperature of the circulated gas. The refrigeration apparatus is ,converted to a heating system by circulating therethrough in heat exchange relation with the gas, heat from a source of supply indicated at 3d which might be a steam boiler plant, the steam being circulated through the pipe connections 56 and 37V with the refrigerating coil. The heated gas is then passed through the distribution duct 2S into and through the adsorbent storage bed i9. On

passing through the adsorbent bed the comparatively warm gas adds heat to it, raising the temperature thereof, adding sensible heat to the adsorbent, and furnishing the latent heat of desorption for the methane adsorbate, thus effecting its release as a free vapor or gas. The desorbed gas thus freed is pumped by a compressor 331 through a heater 39 for release through an orifice meter lil and delivery through pipe 4i. for repressuring the gas supply in a pipe line or for use as desired. ln some cases it may be desirable to store and desorb gas at pressures slightly higher vthan the pressure of the liuc into which the desorbed gas will be injected.

Y case the'compressor 3.8 will not be required.

ln addition to storage of methane, the invention involves separation of methane and/ or other hydrocarbons in natural gas, from nitrogen which, as above stated, oc'- curs in the natural gas in variable amounts from certain natural gas iield sources. The nitrogen not being combustible and having no heat value value of the natural gas mixture on a volume basis. Therefore, nitrogen is usually and justly regarded as an undesirable diluteut or impurity. To avoid the expense handling the nitrogen through a pipeline transmission and distribution system, the nitrogen should be removed.

i have found that nitrogen and methane or' a natural gas mixture can be separated by means of the adsorbent bed when the gas mixture is parsed through a bed ot solid adsorbent with both the mixture and the adsorbent bed a lesser extent as shown in Example 4 hereinafter in- Y. the adsorbent practical to Til' ' adsorbent bed as a free gas.

vgas from the pile of solid at'temperatures just above the'liquefaction temperature oi methane at the contact pressure. Under these temperature conditions, the methane is adsorbed on the adsorbent as an adsorbate, but the nitrogen is'adsorbe-:l to

eluded and the unadsorbed nitrogeupasses through the rthe nitrogen so released can then be disposed of as required under the operating conditions, if it has no further value. Provision is made as shown on the diagram to vent gases from the adsorbent bed back to the pipe line through pipe 42 that connects the pipe 22 with the pipe line l at a point up stream from the connection ofthe pipe 4. f

After processing a methane-nitrogen natural gas mii:-V

ture as described, the adsorbent eventually becomes saturated with the methane adsorbate, and no longer removes methane from the gas mixture under circulation.

The valuable methane adsorbate can be recovered from when needed by circulating gas through the adsorbent bed at a temperature higher than the separation or adsorbing temperature in the `same manner as previously described.

Attention is directed tothe fact that it is possible and desorb at a changed pressure than the adsorption pressure, thus altering the equilibrium to desorb a more favorable temperature or pressure, however, under normal operating conditions desorptionwould be accomplished at adsorption pressure.

If the container of the adsorbent should rupture and the adsorbent spill out on the ground it will not flow as a liquid nor will the gas escape rapidly as a free gas. The adsorbent will merely accumulate in a pile as a solid at the location where it is spilled. On exposure to atmospheric temperatures, the methane will escape slowly as a material. This is because the latent heat of desorption required to release the gas from the adsorbent'as Vapor must be obtained from the atmosphere or other source.V

The results of tests to determine the quantity of methane and nitrogen adsorbed under various conditions are illustrated by the following examples:

Example 1 Results on Athe adsorption or' the adsorbate methane.

in this decreases the E. t. u.;

on the adsorbent attapulgite (activated at' 316 C., 30/60 mesh):

Capacity of adsorbent for adsorbate methane, CH4, at 800 mm. Hg pressure Temperature in Degrees Centigrade +25 C l60 C 16.5 Inl/gram. 340 ml./gram.

Example 2 Results on the adsorption of the adsorbate methane on the adsorbent carbon (commercial sample, 20/60 mesh):

Capacity of adsorbent for adsorbate methane, CH4, at 800 mm. Hg pressure Temperature in Degrees Centigrade +25 C 17.7 Inl/gram. -l59 C 335 Inl/gram.

Example 3 Results on the adsorption of the adsorbate methane, on the adsorbent bauxite (activated at l100 F. 20/60 mesh):

Capacity of adsorbent for adsorbate methane, CIEM, at 800 mm. Hg pressure Temperature in Degrees Centlgrade 12.0 nil/gram. 145 mL/gram.

Capacity of Adsorbent for adsorbate at 800 mm. Hg pressure Temperature in Degrees Centigrade 16.5 ml./g'ram. 340 ELL/gram.

17.4 mL/g'ram. 21.1 Inl/gram.

It is to be emphasized that the drawing is schematic and has been made as simple as possible for illustrative purposes and it is obvious that various bypasses, automatic controls, valves, etc., are used to obtain the most advantageous heat balance and design consistent with economics, engineering, local gas pressures and temperatures and other attendant local gas pressures and temperatures. Such additions, however, will not change the principles of the invention as herein described.

From the foregoing it is obvious that I have provided a practical, safe and economical method of storing methane or natural gas through adsorption by a solid adsorbent material at moderate pressures and a temperature slightly above the liquefaction temperature of methane at the pressure used. It is also obvious that the adsorbed gas is readily released for use when it is desired to augment the iiow volume in a pipe line at times of high demand for gas.

While l have specically illustrated and described the adaption of my invention to the storage and stock piling of natural gas, it is obvious that other gases may be stored in like manner by maintaining a temperature suitable for holding the gas as an adsorbate in an adsorbent material.

What l claim and desire to secure by Letters Patent is:

l. The method of storing a high pressure natural gas on a solid adsorbent material at substantially atmospheric pressure including, liquefying the gas, bringing the liqueied gas into contact with a solid adsorbent material to effect adsorption of liquefied gas on said material, recirculating any vapor evolved during the adsorption to the place of liquefaction, and returning said vapors as' a liquid to the place of adsorption to perature for holding the gas storage period.

2. The method of storing natural gas on a solid adsorbent material and releasing the natural gas from storage when needed for use including, liquefying the gas, bringing the liquefied gas into contact with a solid adsorbent material to etfect adsorption turning any nnadsorbed gas to the place of liquefaction, circulating the liquefied gas to the place of adsorption to maintain the adsorbent at a temperature for holding the absorbed gas in said material While in storage, and heating the adsorbent material to release gas when gas is needed for use.

3. An apparatus for storing natural gas including a closed vessel, insulating material lining the interior of the vessel for providing an insulated chamber in said vessel, a body of solid adsorbent material contained in said chamber, refrigerating means for cooling the natural gas to near the liquefaction temperature of the gas at the pressure to be maintained on said gas, means for condensing the gas after being cooled by said refrigerating means, duct means for supplying natural gas for passage through exchange between the gas supply and the unadsorbed gas, and a compressor in said rst named duct means for ei'rectperature to hold said natural gas as an adsorbate.

4. An apparatus for storing natural gas including a closed vessel, insulating material lining the interior of the vessel for providing an insulated chamber in said vessel, a body of solid adsorbent material contained in said chamber, gas refrigerating means for cooling the natural gas to near the liquefaction temperature of the gas at the pressure to be maintained on said gas, means for condensing the gas after being cooled by the refrigerating means, duct means for supplying natural gas for passage through the refrigerating means and condensing means to the chamber of said vessel, duct means for withdrawing unadsorbed gas from said chamber and returning the unadsorbed gas to the refrigerating change between the gas supply compressor interconnecting said duct means for eiecting movement of the gas supply and unadsorbed gas through the refrigerating means to the storage chamber for maintaining said adsorbent at a temperature to hold said natural gas as an adsorbate, and a separator between the refrigerating and condensing means and said storage chamber for removing condensate and solid materials which might result from cooling of the gas by said refrigerating means.

5. An apparatus for storing natural closed insulated vessel, a body of solid adsorbent material contained in said vessel, gas refn'gerating n cans for cooling the natural gas to near the liquefaction temperature of the gas at the pressure to be maintained on said gas, duct means for supplying natural gas for passage through the refrigerating means, means in said duct means for removing any objectionable materials from the gas, a condenser between the last named means and the vessel for condensing the cooled gas, duct means for withdrawing unadsorbed gas from said vessel and returning the ungas including a Vexchange between the gas supply and the unadsorbed gas,

and a compressor in said rst named duct means for effecting movement of the gas supply and unadsorbed gas Vthrough the refrigerating means to the storage vessel for maintaining said adsorbent at a temperature to hold said natural gas as an adsorbate, Y

6. The method of storing a high pressure natural gas on a solid adsorbent material at substantially low pressure and temperature including, cooling the gas to liquify the gas, bringing the liquied gas into contact with the solid adsorbent material to cool said adsorbent material and to be adsorbed thereby, removing gas that vaporizes incidental to cooling ot the adsorbent material, mixing the vaporized gas with the incoming gas, and liquiiying said mixture for adsorption by the adsorbent material.

7. The method of storing a high pressure natural gas on a solid adsorbent material at substantially low pressure including, cooling the gas to the liquication temperature of the gas, bringing the liquied gas into Contact with the solid adsorbent material to cool said adsorbent material and to be absorbed thereby, removing gas that vaporizes incidental to cooling of the adsorbent material, bringing the vaporized gas into heat exchange relation with the incoming warm gas, and mixing the vaporized gas after said heat exchange with the incoming gas to the place of liquitication.

8. The method of storing a high pressure natural gas on a solid adsorbent material at substantially low pressure including, cooling the gas to a temperature near the liquication temperature of the gas, removing objectionable material from the cooled gas, further reducing the ternperature to liquity the gas, bringing the liquitied gas into contact with the solid absorbent material to cool said afsorbent:r material and to be adsorbed thereby, removing gas that vaporizes incidental to cooling and maintaining temperature of the absorbent irc-m the place o adsorption, bringing the vaporized gas into heat exchange relation with the incoming Warm gas, and mixing the vaporized gas with the incoming gas to the place of cooling.

9. The method of storing a high pressure natural gas on a solid adsorbent material at substantially low pressure and temperature including, cooling the gas to liquify the gas, bringing the liquitied gas into contact with the solid adsorbent material to cool said adsorbent material and to be adsorbed thereby, removing gas that vaporizes incidental to cooling of the adsorbent material, mixing the vaporized gas with the incoming gas, liquifying said mixture for Iadsorption by the adsorbent material, and passing heated gais into contact with the adsorbent material when the adsorbed gas is to -be released 4from storage.,`

10. The method of storingV ahigh pressure natural gas on a solid adsorbent material atV substantially low pressure including, cooling the gas to liquity the gas, bringing the liquiried gas into contact with the solid adsorbent Vmaterial to cool said adsorbent material and to be absorbed thereby, removing gas Vaporized incidental to cooling the adsorbent from the placeof adsorption, bringing the vapoi-ized gas into heat exchange relation with the incoming warm gas, mixing the vaporized gas after said heat exchange with the incominggas, liquiying the mixture at the placent cooling, passing the liquied mixture into contact with the `cold adsorbent material, and passing heated gas into Contact `with theragdsorbred material whenthe absorbed gas is to be released from storage.- Y

ll. The method of storing a high press ire natural gas on a solid adsorbent material at low temperature and presv sure including, cooling the gas to a temperature near the liquication temperature of the gas, removing objectionable matter from the cooled gas, Vcondensing the gas, bringing the condensed gas into Contact with the solid adsorbent material to cool said adsorbent material, removing yaporized gas from the place of adsorption, bringing the vaporized gas into heatl exchange relation with. the incoming Warm gas, and mixing the vaporized gas after said 'neat exchange with the incoming gas. t

Reerences Cited inthe le o this'patent UNlTED STATES PATENTS

Claims

1. THE METHOD OF STORING A HIGH PRESSURE NATURAL GAS ON A SOLID ADSORBENT MATERIAL AT SUBSTANTIALLY ATMOSPHERIC PRESSURE INCLUDING, LIQUEFYING THE GAS, BRINGING THE LIQUEFIED GAS INTO CONTACT WITH A SOLID ADSORBENT MATERIAL TO EFFECT ADSORPTION OF LIQUEFIED GAS ON SAID MATERIAL, RECIRCULATING ANY VAPOR EVOLVED DURING THE ADSORPTION TO THE