KR800000125B1 - Process for recovery of ammonia in liquid ammonia fabric treating system - Google Patents

Abstract

In a process for treating a moving cellulosic web in a confined area with liq. NH3 at near atm. pressure, NH3 was recovered by withdrawing the gas effluents from the zone after the web was heated to vaporize introducing the effluent into a body of anhyd. liq. NH3 at approx. atm. pressure to cool the effluent and to condense the water vapor, compressing condensing the gaseous NH3, withdrawing the liq. NH3-condensed water mixt. from the body and supplying it to treating zone, and replenishing the body of anhyd. liq. NH3 with anhyd. liq. NH3 from the condensing step.

Description

Recovery of Ammonia

1 is a schematic representation of a typical form of a liquid ammonia woven processing system comprising an ammonia recovery system in accordance with the present invention.

2 is a schematic diagram of the main configuration of the ammonia recovery liquefaction system according to the present invention.

The present invention is directed to a system for the recovery of ammonia consumed in connection with processing such as woven fabrics and liquid ammonia, and particularly relates to the removal of ammonia recovered in undesired water.

Economical processing of woven fabrics with liquid ammonia requires the reuse and recovery of substantial amounts of ammonia. During processing, ammonia is inevitably contaminated with water. Separation of water from ammonia at the laboratory level is a theoretically simple problem for any kind of batch processing and can be countered by other conventional evaporation techniques or otherwise. In any case, a substantial amount of anhydrous ammonia is used as a treatment medium in the continuous processing series and water accumulates not only from the woven fabric in the treatment process, but also from any unavoidable amount of air leakage in the system. Because of the large number of recycles in any given increment of the treatment medium, water must accumulate rapidly in the system and be removed in a continuous manner compared to what is actually "used" in the treatment process. The specification is the only method for forming a process effluent, supplying the effluent to a desuperheated vessel and directly contacting the low temperature liquid ammonia fuselage to condense water and ammonia vapor to remove water. Represents a highly efficient process. This is done in connection with the preliminary cold condensation of the effluent in the non-contact heat exchange step. The condensed body of liquid ammonia in the desuperheated vessel contains residual condensate from the process effluent that combines with the reliquefied ammonia and forms a feedstock of the liquid ammonia solution in the process. In the new process that forms part of the feedstock, the water condensed is used in the woven fabric to be treated together with the liquid ammonia. Typically some of the water is conveyed with the woven fabric to be processed as a water content composition. Residues emitted as steam in the process are recycled.

Instead of being sent directly back to the process, the main factor in the new process is that the reliquefied ammonia enters the desuperheater and merges with the condensate effluent there. The mixed solution containing a small amount of condensed residual water is fed back to the process. In this way, the total water content in the process solution should be kept satisfactorily low, typically up to 2 or 3% under extreme process conditions, preferably much lower than under more moderate process conditions.

Woven fabrics consisting of at least some of the cellulose-containing materials can be effectively treated to expose them to liquid ammonia to improve shrinkage resistance and to provide greater affinity for the fabric to other process chemicals. According to the known technique of treating liquid ammonia, the woven fabric is briefly exposed to liquid ammonia, such as by liquid bath deposition. After a predetermined reaction time, which is effectively less than about 9 seconds, the woven fabric is heated to vaporize ammonia to dissipate and terminate the reaction at the desired level.

In a typical liquid ammonia process, only a small percentage of ammonia (eg about 5%) is actually consumed or otherwise lost in the process reaction. The balance is in the form of ammonia vapor. Due to the potentially dangerous and unpleasant nature of ammonia vapors, as well as for economic reasons, it is important to recover the ammonia vapors re-liquefied, reused and consumed by practical liquid ammonia processing operations. Broadly speaking, this can be done by recovering ammonia vapors from the woven processing chamber and by compressing and condensing vapors such as ammonia. The condensed vapor is returned to the liquid ammonia storage tank for last reuse in the system.

In known systems, hot steam from the processing chamber is directed to the desuperheater vessel, where the steam is bubbled through a bath of liquid ammonia at about -28 ° F. The desuperheated gas is then directed through a suitable compression and condensation step, and the resulting liquefied ammonia is returned to the storage tank for final reuse in the process.

While known systems make important advances in the technology of ammonia recovery, the overall operating efficiency is limited in part by the overall accumulation of water in the system. Water is difficult to separate from liquid ammonia because it can condense considerably compared to ammonia. That is, a significant amount of the medium to be treated in the form of anhydrous liquid ammonia is used in a high speed continuous processing system, and most of it is continuously recycled. Since the original system will accumulate water, the process must be shut off and batched or batched. In any case, the ammonia and water properties are so closely related that it is difficult to separate them around a continuous process line corresponding to a conventional laboratory separation process. This water accumulation requires extraction and disposal from the process of water-diluted liquid ammonia every hour. If the circumstances permit, such extraction can be used for fertilizer application. Otherwise the substance must be incinerated or otherwise treated appropriately.

According to the present invention, a unique, highly simplified, and more generally efficient process is provided for removing water accumulation from the liquid ammonia system without requiring the use or destruction of significant amounts of poor liquid ammonia. In the known general form of liquid ammonia recovery system, the process of the present invention is a unique method of inducing liquid ammonia composition flow from the liquid held in the desuperheated vessel into which the spent process steam containing the residual water portion is introduced. Process. In continuous operation processes, the successive effluents of water condensed in the composition liquid prevent significant accumulation of water in desuperheated vessels, with the percentage of water being 2 to 3% under the most extreme positive conditions, much less under more moderate conditions, for example. Is maintained at the level. At that level, water forms relatively insignificant impurities.

According to the above, the woven fabric treatment process was ideally performed in such a way that the water content of the woven fabric was almost left when ammonia was vaporized when the woven fabric was heated after contact with the liquid ammonia to terminate the ammonia reaction. Thus, the woven fabric from the process chamber is accompanied by an additional increase in moisture which is forever removed from the ammonia recovery system.

In some commercial applications of the process, it is not always practical to adjust the process to avoid distilling off significant% of the residual moisture content of the woven fabric. In such cases, the gaseous process effluent will carry a very high percentage of moisture. According to another particular aspect of the invention, process effluents, such as gases, before being discharged in a direct heat exchanger in contact with liquid ammonia in a desuperheater are preferably precooled by a non-contact heat exchanger using liquid ammonia as the light exchange medium. . In addition to the actual heat exchanger, this serves to condense residual water in the gaseous effluent to levels of 2 or 3%.

Regardless of the process used to extract excess water from the continuous process system, whether mechanically draining water with a woven fabric, condensing a portion of the water, or using a desiccant, may be used for water removal, No practical technique is 100% valid. Even in the case of conventional processes, the water is rapidly or slowly scaled up in the desuperheated vessel depending on the efficiency of the water extraction technique and eventually the desuperheated vessel is operated at significantly reduced efficiency. In any case, according to the present invention, the liquid content of the desuperheated vessel containing the condensed residual water is continuously supplied back to the process chamber and recycled through various water removal steps.

Instead of being fed back directly from the reservoir to the processing chamber, ammonia re-liquefied from the recovery system is fed to the desuperheater as a composition for the solution containing the extracted water. Therefore, the water content of the desuperheated container is easily maintained at a moderately low level on the basis of the rectified state.

However, the second advantage of supplying the reliquefied ammonia to the critical desuperheater is that it does not require a separation process for that purpose and at the same time at an operating temperature of -28 ° F (-33 ° C) upstream of a convenient location in the processing room. Pre-cooled. Pre-cooling significantly reduces the system's energy demand as compared to supplying ammonia reliquefied directly to the processing room, which must be maintained at a high temperature. Thus, the process of the present invention is continuous and effectively removes accumulated water on a steady-state basis and at the same time achieves significant efficiency improvements in ammonia recovery systems.

To better understand the above-mentioned features and other features and advantages, refer to the following detailed description and accompanying drawings.

The drawings first systematically illustrate a system useful in carrying out liquid ammonia treatment of woven or spinning as an example in FIG. 1. The purpose of this technique will be clear if the material to be processed is a woven web consisting essentially of cellulose material. In any case, the ability of the treated material to optimize the process efficiency of introducing and conveying a small amount of water is a matter apart and the properties of the material to be treated are not critical to the present invention.

Woven web 10 from a suitable feed (not shown) in FIG. 1 is about one or more heated rollers 12 consisting of a pre-drying section that passes through eleven rollers. To be oriented to. Through a series of pre-drying rollers 12, the woven fabric is sufficiently heated to remove excess moisture. The woven fabric introduced at this point typically contains as much as 7 to 10% water (midrange of the woven fabric). The amount of moisture in the woven fabric excessively interferes with the desired reaction of the liquid ammonia process. It should normally be performed in a liquid ammonia solution containing less than about 10% water. Although the weight of ammonia varies greatly depending on the weight of the fabric in the reaction phase, a relationship of one-to-one (eg, one part of ammonia solution to one part of zippo by weight) is typical. In such cases, if the woven fabric to be introduced carries 10% water, the amount of water will be present at the reaction site and will form about 10% ammonia solution. This is an undesirably high level, as contemplated in the present invention, especially when the ammonia solution itself contains some water. Thus, the predrying step typically removes sufficient moisture to bring the residual water content from about 3 to 5% by weight of the woven fabric. Of course, if the woven fabric being introduced is sufficiently dry first, the predrying step is omitted. The woven fabric leaving the predrying step will undesirably be kept at high temperature and then cooled before being introduced into the liquid ammonia temperature chamber 13. Typically a suitable fan or blower 14 is arranged downstream of the pre-dry section to direct the flow of cooling air to the woven fabric and to return to near ambient temperature levels.

The pre-dried and cooled woven fabric passes through the additional stretch control roller 15 and enters the process chamber 13 through the sealed opening 16. The advantageous form of such openings sealed is described and patented in " Justson Concurrent Application Series No. 490, 202, filed on July 19, 1974 on low friction sealing for woven fabrication process rooms. Typically, the interior of the chamber is kept at a slight negative pressure along the periphery and the entry opening 16 is double sealed.The intermediate chamber between double seals is inevitably kept at a negative pressure slightly greater than the interior of the seal. Slight leakage from the seal is directed into the intermediate chamber, which minimizes the leakage of ammonia vapor from the process chamber at atmospheric pressure In a typical process the main treatment chamber is operated at a negative pressure of about 0.5 (inch) H ₂ O The intermediate chamber shall be maintained at a negative pressure of approximately 0.75 inch H ₂ O.

A trough 17 to be processed in the simple arrangement described in FIG. 1 is provided in the processing chamber 13. Through proper control (not shown and not part of the present invention), this trough supplies a liquid ammonia solution for processing through an internal feed line 18. Control of this will include a Valve (not shown) to keep the processing liquid at an appropriate level in the trough.

After entering the processing chamber, the woven fabric is led to trough 17 and then deposited in a liquid ammonia solution at a temperature of about -28 ° F. It is then directed through padding rollers 19 to extract the excess processing solution and then to a series of adjustable timing rolers 20. After a predetermined reaction time, the woven fabric is contacted with a heat source to flow liquid ammonia. In the system described there is a pair of Palmer-type dryers 21, 22. This includes a heated drum 23 surrounded by a closed blanket 24. For practical purposes the ammonia reaction essentially decreases shortly after the initial contact between the woven fabric and the first dryer drum. Advantageously the time interval between initial deposition and initial contact with the first dryer drum in liquid ammonia should be controlled in the range of 0.6 to 9 seconds. This can effectively control the distance traveled between the trough 17 and the first dryer 21 by adjusting the roller 20 to make the path of the web moderately short or long. In any case, with respect to the control of the operations of dryers 21 and 22, except for the control of water in woven fabrics and processing solutions, certain process conditions do not form part of the invention.

After leaving the second dryer stage 22, the woven fabric leaves the main treatment chamber 13 through the outlet 25. This opening, such as entry and exit 16, is effectively double sealed with an intermediate chamber maintained at a negative pressure slightly greater than the process chamber itself.

The woven fabric leaving the main treatment chamber 13 is effectively directed to the steam chamber 26 and the woven fabric will then be conveyed, for example, to a folding machine or winder.

Only about 5% of the liquid ammonia supplied to trough 15 is actually consumed in the processing of woven fabrics in the main treatment chamber 13. The remainder is released as ammonia vapor. Not only is this steam potentially dangerous, but its reuse is economically important in continuous commercial processes. The recovery of the ammonia vapor has been performed by recovering the vapor from the process chamber, compressing it, and condensing it.

Although a significant amount of air is contained in the normally recovered gas, air is easily separated from ammonia because of its relative incondensability. The recovered gas also contains a large amount of water, which, regardless of the efficiency of the exit and inlet sealing, is present in a significant amount in the space between the woven fabrics and is continuously processed due to the basic moisture content of the woven fabric entering the woven fabric and the air moisture content introduced. Enter In the past, such an amount of water was difficult to remove as described above, and therefore sometimes required to be used as a lower end product, such as discarding a substantial amount of diluted liquid ammonia and using it as a fertilizer.

The process of the present invention relates to the recovery of ammonia consumed in such a way that water can be removed easily and effectively as a continuous process. Thus, the process reaction is otherwise relatively pure anhydrous ammonia is not inhibited by excess water in the solution, and the maximum utilization of liquid ammonia in the processing operation can be realized.

In the schematic diagram of FIG. 1, the decompression line 27 is guided from the main processing chamber 13 to effect effective continuous recovery of gas from the inside of the chamber. This gas is initially directed to the recovery portion, generally designated by number 28 in FIG. 1, in which the gas is processed to compress, condense, and separate the air from the liquid ammonia. The liquid ammonia reservoir 29 is provided for instantaneous contamination of the recovered liquid ammonia. As described in more detail in FIG. 2, the internal feed and 18 supplied through the processing trough 17 are not directly connected to the reservoir 29 but to the recovery portion 28. The stored liquid ammonia is first directed back into the recovery system using the method described from vessel 29 and then directed to the processing trough 17 along with the incremental water extracted from the recovered gas.

According to a typical practice, the air separated from the recovery system is directed to an incinerator or other treatment plant 30. Alternatively from the steam chamber 26 a mixture of air and steam containing some residual ammonia gas is directed to the treatment plant via the decompression line 31. It is considered uneconomical to attempt to recover it because of the relatively small amount of ammonia in this gas.

Referring to the system table of FIG. 2, the decompression line 27 is shown connected from the processing chamber to a non-contact heat exchanger 32 in the form of a round tube at both ends. The recovered gas, which consists mainly of ammonia gas and also contains a large amount of air and water vapor, passes through the shell side of the exchanger, while the cooling medium flows into the tube side of the exchanger.

Advantageously, the non-contact exchanger 32 has two heat exchange stages consisting of a cooling stage. In the cooling step, water is used as the heat exchange medium flowing through lines 33 and 34. At this stage, gases leaving process chamber 13, typically at a temperature of about 150 ° F., are precooled to about 90 ° F in the water portion of the exchanger. Liquid ammonia is preferably used as the non-contact heat exchange medium in the second stage of the hot air ventilation. Liquid ammonia is supplied through lines 33a and 34a, which serve to cool the outgoing process gas from about 28 ° F to about -210 ° F at a precooled temperature of about 90 ° F.

According to one aspect of the invention, the cold cooling of the effluent gases in the second stage of the heat exchanger 32 serves to condense the essential part of the residual water content with the gas.

This molten water portion can be discharged to 32a and collected for further processing or lower use.

Due to the extremely affinity of ammonia for water, the portion of water condensed in the heat exchanger 32 will inevitably absorb some ammonia. So the condensate extracted at 32a is typically about 50% mixture of water and ammonia. The total amount of condensate collected is generally very small. So typically a commercial feed requires about 3,000 pounds of woven fabric per hour and about 2,500 to 3,000 pounds of liquid ammonia solution per hour and the recovery of condensate is on the order of 8 to 10 gallons per hour, almost half of which is ammonia. At this stage, at least any amount of ammonia in the condensate was recovered without great difficulty, as long as the recovery of ammonia became economically important in a sufficiently large volume of the process.

Gases cooled from the heat exchanger 32 are directed to a desuperheater 36 comprising a liquid ammonia body 37. In the process of the present invention, the desuperheating vessel is maintained at slightly negative pressure and the liquid ammonia fuselage 37 is maintained at a temperature of about -28 ° F. (or slightly higher, mainly along the entire water portion). Process gases will be charged directly into the bottom of the desuperheated vessel and bubble up through the cold liquid ammonia. In turn, the process gases were sprayed with liquid ammonia. In either case, direct contact heat exchange prevents overheating from the ammonia gas so that the cooled gas accumulates in the upper 38 of the vessel along with the incidental gas flowing out of the liquid itself, thereby maintaining the liquid ammonia low temperature and liquid phase. do.

The suction line 39 connects the upper part of the desuperheating vessel 36 with the suction line of the compressor 40 adjusted by the motor 41. Gases consisting primarily of desuperheated ammonia gas with air in the compressor will be compressed at a pressure of about 180 psig as an example. The compressed gases are essentially heated by compression and leave the compressor through high pressure tube 42 at a temperature of about 100 ° F. The high pressure pipe 42, which is led to the rounded side of the round tube cooler-heat exchanger 43, cools the piped water by the inlet pipe 44 and the outlet line 45.

The liquid ammonia, now condensed from the cooler 43 at a temperature of about 95 ° F., flows into the storage and storage vessel 29 through the high pressure tube 46. Uncondensed steam from the cooler-heat exchanger 43 is recovered through the tube 47 and introduced into the purging vessel 48 so that the uncondensed steam flows through non-contact heat exchange with low temperature (typically -28 ° F) liquid ammonia. Condensation. The material condensed from the purging vessel 48 flows through the tube 49 through the desuperheating vessel 36 where the liquid portion of such material is added to the liquid ammonia body, and any contained gaseous portion is bubbled through the liquid ammonia and recycled. do. Liquid ammonia, introduced from the storage vessel 29 used for cooling the purging vessel 48, is introduced into the tube side of the purging vessel through a suitable expansion valve 50, which is typically a round tubular heat exchange vessel. After passing through the tubing side of the purging vessel, liquid ammonia is introduced into the desuperheating vessel with the flow of condensate flowing through the outlet line 51 and in the line 49.

According to an important point of the present invention, the liquid ammonia demand of the process is supplied to the main treatment chamber entirely or in placenta via tubes 18, which are not directly from the storage vessel but preferentially from the desuperheating vessel containing the effluent.

For this purpose, the vessel 36 has an outlet line 52 which is connected to the inlet of a suitable pump 53 and discharged through a control valve device 54 to a tube 18 which is connected to the treatment trough 17. Advantageously, the desuperheating vessel 36 sets up the upper and lower limits of the ammonia level in the container by installing appropriate liquid level detection elements 55 and 56.

The liquid ammonia feed from the high pressure mixing vessel 29 and valve 57 at 58 introduce liquid ammonia into the desuperheating vessel by regulating by means of detection elements 55 and 56 to maintain the desired level in the desuperheating vessel as required.

As can be appreciated, the new, relatively pure anhydrous ammonia is introduced into the desuperheated vessel 36 from the reservoir 29, which serves a variety of functions. The first liquid is introduced into an equilibrium at a slight negative pressure and -28 ° F temperature in a superheated vessel, for example, introduced into a superheated vessel maintained at a relatively high temperature of 95 ° F and a relatively high pressure of 180 psig. Any amount of new liquid ammonia that is released is soon dissipated to equilibrium, causing self-cooling. In a typical process, 75% of liquid ammonia remaining from the reservoir by 25% by weight causes self-cooling to -28 ° F and is discharged as a gas.

If the reliquefied ammonia is taken directly from the storage vessel 29 to the treatment chamber in the process of the invention, a significant advantage is realized by the self-cooling of the reliquefied ammonia in the desuperheating stage rather than in the treatment chamber 13.

A considerable volume of ammonia is required to self-cool and this volume is released in process chamber 13 as in the past, which increases the energy demand of the heating area of the process chamber and likewise increases the cooling demand of the ammonia recovery system. Play a role.

In the system operation of FIG. 2, the liquid ammonia containing a small amount of water is directed through the pipes 52 and 18 to the processing chamber 18 and supplied directly to the trough 17. Woven 10 continues to advance to the processing room at a predetermined rate. The woven fabric enters the processing chamber and is deposited in trough 17 and saturated with liquid ammonia solution.

When the processing unit is in steady state conditions, the yarn 13 is completely saturated with ammonia vapor, effectively saturating with liquid ammonia when the woven material comes out of trough 17 and advances to the first contact point with the dryer 21. During this period, an important necessary reaction occurs between ammonia and woven fabrics. Shortly thereafter, the woven fabric is released to almost terminate the reaction and the balance is essentially removed by the dryer 21, 22 or woven process.

Although the relationship between the woven fabric to be processed versus the ammonia solution to be used differs significantly from that of other woven fabrics, the one pound liquid ammonia feed to the one pound woven feed is typical but is adopted here for illustrative purposes. Thus, for each pound of woven fabric introduced into the yarn, one pound of liquid ammonia solution is absorbed from the trough 17 and conveyed along with the movable woven fabric and approximately 95% is emitted by the dryers 21 and 22.

Thus, about one pound of gas consumed relative to each pound of woven fabric being processed will be recovered from process chamber 13.

The air pressure in process chamber 13 will inevitably be partially diluted by air and moisture because the woven fabric carries the air trapped in the cross section and the air inherently contains some moisture. This will occur despite the efficacy of sealing at the inlet and outlet openings. When the gas mixture mainly composed of ammonia is recovered into the chamber and foamed through the overheating vessel, the water part in the gas easily condenses in the liquid ammonia body 37 of about -28 ° F. In addition, due to certain processing operations, the additional moisture fraction is released from the woven fabric by the heat of dryers 21 and 22. Unless properly handled, the foreign body must accumulate in the vessel 36 and gradually increase the temperature of the bath 37 so that it no longer serves its intended purpose and must be used for extraction, disposal or use of lower grades. In any case, according to the present invention, the liquid ammonia containing water in the desuperheating vessel 36 is used as a composition feed in trough 17 which is subsequently extracted and deposited through line 52.

As an integral part of the process of the present invention, the continuous removal of water from the process is provided on a convenient and economic basis. Although the special techniques used for water extraction are not critical to the basic process of the present invention, it is of course important that some devices be equipped for water removal.

More advantageously one of the special advantages of the present invention is of course the most convenient by the combination of several techniques, including withdrawing the water with a mechanically treated woven fabric and condensing the water fraction in the hot effluent gaseous extracted from the treatment chamber. Is removed. Thus, if processing conditions permit, it is advantageous to adjust the time-temperature relationship of the heating portion to discharge the ammonia portion, essentially keeping the water portion in the woven fabric intact. In this way, the woven fabric leaves the process with a slightly larger moisture content each time it is introduced, resulting in pure deodorization of the water from the processing system.

The second preparation requires precooling the hot effluent from the process to condense at least a portion of the water in the spent gas since not all fabrics and all processing conditions allow for optimal control of the heating portion. Liquid ammonia, which is useful as a coolant, is carried out in a practical non-contact heat exchanger and cooled to about -21 ° F to reduce the amount of water consumed, for example, by 2-3%. Thus, optimum process efficiency will be realized by removing water by condensation from woven conveying or hot water gas. As long as the nature of the woven fabric and the special treatment process is allowed, the heating stage can be adjusted to achieve a pure outflow of water from the woven fabric itself. In any case, the process cannot be operated in an ideal manner and the resulting moisture content of the hot effluent gas will be significantly reduced by cooling in the non-contact heat exchanger 32.

The system of the present invention is uniquely effective in eliminating undesirable amounts of water accumulation in the system by means of a liquid ammonia fuselage containing water in the desuperheated vessel for the supply of process solutions and at the same time significantly improving the thermodynamic efficiency of the system. have. By supplying this solution back to the process, it is possible to prevent the portion of the water present in the originally recovered process gas from accumulating and becoming undesired and removed at a convenient stage of the process.

Under ideal conditions of process operation, the steady-state residual water content in the desuperheated vessel will be maintained at an extremely low level. Under poor conditions, both the primary treatment process itself and the recovery system are operated at high efficiency levels, so that the desuperheated gear water content is easily maintained at levels (2-3% or less).

One of the important additional advantages of the unique process is the improved thermodynamic efficiency obtained by feeding the re-liquefied ammonia into the desuperheater than in the direct treatment chamber 13. Thus, ammonia re-liquefied in the reservoir 29 is maintained at high pressures and quite high temperatures. In use, liquid ammonia should be brought to equilibrium at nearly atmospheric pressure (actually slightly below atmospheric pressure) and at an equilibrium temperature of about -28 ° F. To achieve this equilibrium, most of the reliquefied ammonia is released as a gas. When this happens in the desuperheating vessel, the substantial amount of gas emitted is only recycled through the recovery system and compressed, thereby re-liquefying. If, on the other hand, the gas is emitted in process chamber 13 in accordance with the precedent, the emitted gas is returned to the recovery system only after being exposed to substantial heat in the process chamber. As can be appreciated, the heat that raises the gas temperature in such a portion that is dissipated to bring liquid ammonia to equilibrium conditions is represented by the consumption of thermal energy in the heating portion of the process. Likewise, the side must be removed from the gas to reliquefy and recover the gas, which increases the burden on the compressor. Thus, in this new process, the water content of the system is not only stabilized at the appropriate equilibrium level by deriving the process feed from the desuperheated vessel and using reliquefied ammonia supplied as a composition feed to the vessel without sending it directly to the process chamber. Significant thermal efficiency is achieved.

The system of the present invention is uniquely effective in removing unnecessary water from the recycled ammonia system. Since the ratio between the amount of ammonia recycled in the process and the amount of ammonia consumed essentially is almost 20 to 1, this efficient regeneration technology is extremely important, so this system is very important in practical and economical systems. Up until now, this technology has inevitably been severely limited by the practical difficulties of removing the water system introduced into the system.

The process and system of the present invention operate on the basis that the water content is directly decondensed by direct contact with the cold liquid ammonia body with or without a non-contact condensation step beforehand to feed the composition feed to the process. The water condensed in the deaeration and heat is then introduced directly into the process as fast as it is introduced, so that experience shows that the steady state level is low enough to have a meaningless effect on the process reaction. Therefore, the water content of about 10% in the liquid ammonia solution almost suppresses the required reaction, while the amount of water introduced into the treatment solution according to the present invention shows a relatively negligible increase. In any case, it is necessary to pre-dry the woven fabric in order to minimize the water content introduced in any case and under certain conditions the water content can be removed by the woven fabric.

Therefore, in the ideal process, the moisture content is reached to 5% level, and the required liquid ammonia reaction is left, for example, to leave the process at a moisture content of about 5.1%. In this way, the cloth itself is responsible for the continuous extraction of water from the ammonia recovery system, allowing the system to operate on a very efficient basis, minimizing the use of waste or recovered material as a lower end. If these ideal conditions cannot be realized, other methods, such as contactless condensation of the gas used, are used for water extraction.

It is intended that the form of the invention may be varied without departing from the obvious teachings of the present disclosure, of course only the representative illustrations and description herein. Therefore, reference should be made to the appended claims in defining the overall scope of the invention.

Claims (1)

The gaseous effluent consists mainly of gaseous ammonia, air, and water vapor, which is derived by successive treatment of a mobile cellulose-containing web with essentially anhydrous liquid ammonia, where the mobile web is at a pressure near atmospheric pressure. 12. A method for recovering ammonia, comprising continuously exposing to the liquid ammonia in a closed treatment zone and further wherein the web is subsequently heated and vaporized in the zone to remove liquid ammonia from the web; After recovering the gaseous effluent continuously from the zone, and continuously removing less than all of the water vapor from the gaseous treatment zone effluent, the recovered gaseous effluent is cooled to gas ammonia and vaporized from the gaseous ammonia. Continuously introduced into an almost anhydrous liquid ammonia body maintained at atmospheric pressure for condensation, and then compressed and condensed gaseous ammonia, and continuously anhydrous liquid ammonia together with water condensed from the body is continuously Recirculating gaseous effluent, characterized in that the liquid is recovered and supplied for the exposure step into the treatment zone, and essentially supplemented with anhydrous liquid ammonia from the compression and condensation step with essentially liquid ammonia. Recovering ammonia from water Way.

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