JPS5853108B2 - Method for recovery and reuse of ammonia in systems for treating textiles with liquid ammonia - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This application is a continuation in part of my pending application Ser. No. 490,202, filed in the United States on July 19, 1974.

This application and the present invention are assigned to CluetttP.
B transferred to eabody & Q), Inc.
U.S. Patent No. 372109 to r1ley et al.
This is related to the subject matter of No. 7 and is an improved method thereof.

Fabrics composed at least in part of fibrous materials are advantageously processed by treatment with liquid ammonia in order to improve the resistance to shrinkage and to improve the compatibility of the fabrics with other processing agents. .

According to known liquid ammonia treatment techniques, exposure to a liquid ammonia solution may be accomplished simply by, for example, immersion in a bath of liquid ammonia.

After a period of reaction time, preferably about 9 seconds or less, the fabric is heated to evaporate and drive off the ammonia and terminate the reaction at the desired level.

In typical liquid ammonia processing methods, only a small amount of ammonia (eg, about 5%) is actually consumed or otherwise lost during the processing reactions.

The remainder is in the form of ammonia vapor.

Due to the potentially hazardous and unpleasant nature of ammonia vapor, and also for obvious economic reasons, in actual liquid ammonia processing operations, spent ammonia vapor is not used for reliquefaction and reuse. It is important to collect them.

Broadly speaking, this is accomplished by drawing ammonia vapor from the fabric processing chamber and compressing and condensing such vapor.

The condensed vapor is returned to the liquid ammonia storage tank and reused within the system as needed.

One advantageous method of recovering and reusing ammonia vapor is disclosed in U.S. Pat.
No. 21097.

In the system of the No. 13 Riley et al. patent, hot steam from the processing chamber is directed to a desuperheating vessel in which the steam bubbles through a bath of liquid ammonia.

The liquid ammonia bath may be at a temperature of about -28°C below.

The desuperheated gas is then directed to appropriate compression and condensation stages, and the liquefied ammonia produced is returned to the storage tank and ultimately reused within the process.

U.S. Patent No. 37210 to Br1ley et al.
Although No. 97 represents a significant advance in ammonia recovery technology, overall operating efficiency is limited in part by the gradual accumulation of water within the system.

Water is difficult to separate from liquid ammonia because it is highly condensable with respect to ammonia.

That is, in high speed continuous processing trains, large quantities of processing media in the form of anhydrous liquid ammonia are used, and large quantities must be continuously circulated.

Since this system inherently accumulates water, it must be adapted to both batch processes, where it is necessary to shut down the series, as well as continuous processes.

However, because the properties of ammonia and water are closely related, their separation is difficult in a continuously operating processing chain environment, unlike traditional laboratory separation methods.

Such water build-up sometimes required extraction and disposal from the water-diluted liquid ammonia process.

If circumstances permit, such extracts may be used for fertilizer applications.

Otherwise, such materials must be incinerated or otherwise disposed of appropriately.

In accordance with the present invention, a unique, highly simplified, and totally effective method is provided for continuously extracting aqueous condensate from a liquid ammonia recovery system without requiring the destruction or low-grade utilization of large amounts of liquid ammonia. Provided for removal.

The method of the present invention is a liquid ammonia recovery system of the general type described in the patents of Briley et al. Includes a unique method of extracting the ammonia make-up stream to the processing chamber.

In continuous operation methods, the continuous flow of condensate water in the make-up stream prevents significant accumulation of water in the desuperheating vessel, keeping the water fraction at a level of 2-3% even under the most extreme processing conditions. , and kept at even lower levels under more favorable conditions.

At these levels, water represents a relatively minor impurity.

Related to the above, ideally the fabric treatment process would be such that when the fabric is contacted with liquid ammonia and then heated to terminate the ammonia reaction, the ammonia is evaporated but the moisture content of the fabric is substantially reduced. It is done in the same way as it is.

The fabric coming out of the treatment chamber is then enriched with moisture, which is thus permanently removed from the ammonia recovery system.

In certain commercial applications of the process, it is not always practical to adjust the process to avoid distilling off a significant percentage of the residual moisture content of the fabric.

In such cases, the gaseous processing effluent contains a very high percentage of water.

According to another particular aspect of the invention, such gaseous process effluent is precooled by non-contact heat exchange before being discharged into direct heat exchange contact with liquid ammonia in a desuperheating vessel.

At this time, it is preferable to use liquid ammonia as a heat exchange medium.

In the case of heat exchange equipment of practical proportions, this serves to precondense residual moisture from the gaseous effluent to a level of 2-3%.

The method used to extract excess water from a continuous processing system may be by mechanically transporting it away with the fabric, by condensing a portion of it, or by using some other method such as a desiccant. Regardless of the method, no practical method of moisture removal is 100% effective.

Because of this, in conventional methods, water accumulates in the desuperheating vessel, either rapidly or gradually, depending on the efficiency of the water extraction technology, to the point where the vessel operates at significantly lower efficiency.

However, in accordance with the present invention, the liquid content of the desuperheating vessel, including residual condensed water, is continuously returned to the processing chamber and recycled through various water removal stages.

The reliquefied ammonia from the recovery system, instead of being returned directly from its storage vessel to the processing chamber, is supplied to the desuperheating vessel as a make-up for the extracted water-containing solution.

Therefore, the water content of the desuperheating vessel is easily maintained at a sufficiently low level.

A secondary, but important, advantage of supplying the reliquefied ammonia to the desuperheating vessel is that by doing so it can be delivered at a convenient point upstream of the process chamber without requiring a separate method for that purpose. It is simultaneously precooled to its operating temperature of -33°C.

Compared to the method of supplying reliquefied ammonia directly to the processing chamber, where high temperatures must be supplied, precooling significantly reduces the energy requirements of the system.

In this way, the method of the invention not only effectively removes accumulated water in a continuous and reliable manner, but at the same time achieves a significant efficiency improvement in the ammonia recovery system.

For a better understanding of these and other features and advantages, please refer to the following detailed description and accompanying drawings.

FIG. 1 is a simplified schematic representation of a typical configuration of a liquid ammonia textile processing system including an ammonia recovery system according to the present invention.

FIG. 2 is a simplified schematic representation of the major components of an ammonia recovery and liquefaction system according to the present invention.

Referring first to FIG. 1 of the drawings, there is shown diagrammatically an advantageous method for carrying out liquid ammonia treatment of, for example, fabrics or yarns.

For the purpose of this description, it will be assumed that the material to be processed is a fabric consisting essentially of fibrous material.

However, apart from the ability of the material to be processed to optimize processing efficiency by receiving and carrying away small amounts of water, the properties of the material to be processed are not important to the invention.

In FIG. 1, a fabric 10 coming from a suitable supply location (not shown) passes through tensioning rollers 11 and around one or more heated rollers 12 forming a pre-drying section. Directed.

As it passes through a series of pre-drying rollers 12, the fabric is heated sufficiently to drive off excess moisture.

It should be noted that the incoming fabric may typically contain moisture on the order of 7-10% of the weight of the fabric.

The presence of this amount of moisture in the fabric significantly interferes with the desired reaction of liquid ammonia processing.

This reaction should normally be carried out in a liquid ammonia solution containing less than about 10% water.

Although the weight of ammonia relative to the weight of fabric in the reaction may vary over a wide range, a one-to-one relationship (1 part ammonia solution to 1 part fabric by weight) is not atypical.

In such a case, if the incoming fabric contains about 10% water, such an amount of water will be present at the reaction site, and about 10% of the ammonia solution
%.

This is an undesirably high level, especially when the ammonia solution itself contains some water, as contemplated in the present invention.

Typically, therefore, the pre-drying step is adjusted to drive sufficient moisture from the fabric to leave a residual moisture on the order of 3-5% by weight of the fabric.

Of course, if the incoming fabric is sufficiently dry and ready to start, the pre-drying step may be omitted.

The fabric exiting the pre-drying stage will be at an undesirably high temperature and is therefore cooled before entering the liquid ammonia temperature chamber 13.

Typically, a suitable fan or blower means 14 is located downstream of the pre-drying section to direct a stream of cooling air onto the fabric to return it to a level near room temperature.

The pre-dried and cooled fabric is passed through another tensioning roller 1
After passing through 5, it enters the processing chamber 13 through a sealed hole 16.

An advantageous form of sealing of such holes is described in Jackson Lawrence, filed in the United States on July 19, 1974.
Patent application ``Low-Friction Pressure Sealing Apparatus for Textile Processing Chambers'' is described and claimed in the pending application ``Low Friction Pressure Sealing Apparatus for Textile Processing Chambers.''

Normally, the inside of the room is kept at a slightly negative pressure relative to the atmosphere.
The inlet hole 16 is equipped with a double seal.

Since the intermediate chamber between the double seals is kept at a slightly higher negative pressure than the interior of the processing chamber, any unavoidable small leakage of the seal will tend to be directed into the intermediate chamber.

This minimizes leakage of ammonia vapor from the process chamber into the atmosphere.

In a typical process, the main processing chamber is approximately 0.5" H2
It is operated at a negative pressure of O, but the intermediate chamber is approximately 0.75''H20
maintained at negative pressure.

In the simplified arrangement shown in FIG. 1, a processing tank 17 is provided within the processing chamber 13.

This tank is supplied with liquid ammonia processing solution through an inlet pipe 18 by means of a suitable regulating device (not shown in the figures and forming no part of the invention).

The regulating device may include a float valve (not shown) to maintain the processing fluid at the appropriate level within the tank.

After entering the processing chamber, the fabric is introduced into the tank 1γ and the temperature is about -2
It is immersed into a liquid ammonia solution at a temperature below 8.

It then passes through a padding roller 19 to extract excess processing liquid and then around a series of adjustable timing rollers 20.

After a predetermined reaction time, the fabric is contacted with a heat source that flash-evaporates the liquid ammonia.

In the processing system shown in the figure, a pair of Balmer-type drying devices 21 and 22 are provided.

These include a large heated cylinder 23 around which a restriction blanket 24 is drawn.

For practical purposes, the ammonia reaction is substantially reduced immediately after initial contact between the fabric and the first drying cylinder.

It is advantageous to adjust the time interval between the first immersion in liquid ammonia and the first contact with the S-drying cylinder to be in the range from 0.6 seconds to 9 seconds.

This can be effectively adjusted by adjusting the passage distance between the tank 11 and the first drying device 21.

For example, the rollers 20 are adjusted to lengthen or shorten the path of the fabric as appropriate.

However, other than with respect to the regulation of the water in the fabric and in the processing solution, and with respect to the regulation of the operation of the drying devices 21, 22, the individual processing conditions do not form part of the invention.

After leaving the second drying stage, the fabric exits the main processing chamber 13 through the discharge hole 25.

Advantageously, this hole, like the inlet hole 16, is provided with a double sealing device and the intermediate chamber is maintained at a slightly higher negative pressure than the process chamber.

Advantageously, the fabric leaving the main treatment chamber 13 is passed through a steam chamber 26.

The fabric may then be transported to a folding device, a weighing device, etc., for example.

During textile processing in the main processing chamber 13, only about 5% of the liquid ammonia supplied to the tank 11 is actually consumed.

The remainder is evaporated as ammonia vapor.

Not only are these vapors potentially hazardous, but their reuse is economically important in continuous commercial processes.

Until now, ammonia vapor recovery has been accomplished by extracting the vapor from the process chamber and compressing and condensing it.

Although significant amounts of air are normally contained within the drawn gas, air is easily separated from ammonia due to its relative non-condensability.

The extracted gas also contains some amount of water.

This is due to the basic moisture content of the fabric and due to the amount of air that is present in the interstices of the fabric and enters with the fabric, regardless of the efficiency of the inlet and outlet seals, which continuously enters the process. come.

Such amounts of water have, as mentioned above, been considered difficult to remove in the past, and some amounts of diluted liquid ammonia have sometimes been discarded or used as fertilizer. It was necessary to use it as a low-grade material.

The method of the present invention is directed to recovering spent ammonia by a method that allows easy and effective continuous removal of moisture.

As a result, processing reactions are not hindered by excess water that is already dissolved in the relatively pure anhydrous liquid ammonia, and
Maximum utilization of liquid ammonia in processing operations is achieved.

In the simplified diagrammatic representation of FIG.
Suction pipe 2γ to continuously draw out gas from the inside of 3
is connected from the main processing chamber 13.

These gases are first directed to a collection section, indicated generally by the numeral 28 in FIG.

In this recovery section, the gas is processed to compress and condense the liquid ammonia and separate the air.

A liquid ammonia storage container 29 is provided to temporarily store the recovered liquid ammonia.

Processing tank 1, as described in further detail with respect to FIG.
1 is not directly connected to the storage container 29, but is led from the recovery section 28.

The stored liquid ammonia is first returned to the recovery device from the vessel 29, where it is utilized by the method described below and then directed to the processing vessel 11 together with an increasing amount of water extracted from the recovered gas.

In conventional practice, the separated air from the recovery device is directed to an incinerator or other disposal facility 30.

Similarly, the air and steam mixture from the steam chamber 26, containing some residual ammonia gas, is also led through the suction pipe 31 to the disposal facility.

Since only relatively small amounts of ammonia are present in these gases, it would be considered uneconomical to attempt to recover it.

Referring now to the schematic diagram of FIG. 2, there is shown a suction pipe 21 leading from the processing chamber 13 to a shell-and-tube type non-contact heat exchanger 32.

The withdrawn gas, which is primarily ammonia gas and also contains some air and water vapor, is passed through the cylindrical side of the exchanger, and the cooling medium is passed through the tube side of the exchanger.

Advantageously, the non-contact heat exchanger 32 has two exchange stages, a cooling stage and a cooling stage.

During the cooling phase, water may be utilized as a heat exchange medium and is flowed through tubes 33,34.

At this stage, the gas exiting the process chamber, typically at a temperature below about 150°F, is precooled to about 90'F in the water section of the exchanger.

Preferably, liquid ammonia is utilized as the non-contact heat exchange medium in the second stage of the heat exchanger.

Liquid ammonia is introduced into tubes 33a, 34 at a temperature of about -28 m below.
a, which serves to cool the effluent process gas from a pre-cooling temperature of below 90°C to, for example, about 21'F.

According to one aspect of the invention, cryogenic cooling of the effluent gas in the second stage of heat exchanger 32 serves to condense a significant portion of the residual moisture content from the gas.

This condensed water portion is discharged from 32a and collected for further processing or lower grade use.

Since ammonia has a very high affinity for water, the water portion condensed in the heat exchanger 32 will inevitably absorb some ammonia.

The condensate extracted in 32a is therefore typically an approximately 50% mixture of water and ammonia.

The total amount of condensate collected is generally negligible.

Thus, in a typical commercial processing process, for example, 3000 bonds of fabric may be processed per hour, and thus approximately 2500
In cases requiring the processing supply of 3000 bonds of liquid ammonia, the condensate withdrawal rate is 8 to 10 per hour.
gallons, about half of which is ammonia.

Insofar as the amount of ammonia removed at this stage becomes economically significant in processes of sufficiently high overall volume, at least some of the ammonia content of the condensate will be recovered without great difficulty.

The cooled gas from heat exchanger 32 is directed into a desuperheating vessel 36 containing a body 37 of liquid ammonia.

In the method of the invention, the desuperheating vessel is maintained at a slightly negative pressure and the body of liquid ammonia therein is
(or slightly higher, depending primarily on the amount of total water portion).

The incoming process gases may be discharged directly into the lower part of the desuperheating vessel 36 and vented upward through cold liquid ammonia.

Alternatively, liquid ammonia may be sprayed into the processing gas.

In either case, direct contact heat exchange serves to remove superheat from the ammonia gas.

The cooled gas then accumulates in the upper part 38 of the container together with the gas evaporated from the liquid ammonia itself;
Maintain its low temperature and liquid phase.

A suction pipe 39 connects the desuperheating vessel 36 to a compressor 40 driven by a motor 41 .

In the compressor 40, the gas containing air, which is mainly composed of ammonia gas whose superheat has been reduced, is, for example, about 180%
Compressed to a pressure of psig.

The compressed gas is substantially heated by the compression and is approximately lO
It exits the compressor through high pressure line 42 at a temperature below O.

The high pressure pipe 42 is led to the cylindrical side of a cylindrical multi-tubular condenser/heat exchanger 43.

The condenser/heat exchanger has inlet and outlet pipes 44, 45.
It is cooled by water supplied to the multi-tube side.

The liquid ammonia condensate from condenser 43 is now at a temperature of about 95° C. below and is flowed through high pressure pipe 46 into storage and holding vessel 29 .

Uncondensed vapor from the condenser/heat exchanger 43 is removed through pipe 41 and directed to a wash vessel 48 where the uncondensed vapor is exposed to low temperature (typically -28'F) liquid ammonia and non-contact heat. It is flowed in an exchange state and allowed to condense.

The condensate from the wash vessel 48 is passed through a tube 49 into the desuperheating vessel 36 where the liquid portion of the condensate enriches the volume of liquid ammonia and the contained gas portion, if present, is vented through the liquid ammonia. and recirculated.

Liquid ammonia for draining the wash vessel 48 is drawn from the holding vessel 29, passed through a suitable expansion valve 50, and directed to the tubular side of the wash vessel.

The washing vessel is typically a shell-and-tube heat exchange vessel.

After the liquid ammonia passes through the multi-tube side of the cleaning container 48,
It may be routed through the discharge pipe 51 and combined with the condensate flowing in the pipe 49 to a desuperheating vessel.

According to an important aspect of the invention, the ammonia requirements of the process are supplied entirely or in large part to the main process chamber 13 through line 18 .

This tube 18 is not led directly from the storage vessel 29, but from the desuperheating vessel 36 which initially received the effluent.

For this purpose, the container 36 has a discharge pipe 52.

This pipe is led to the intake side of a suitable pump 53 which discharges through regulating valve means 54 into a pipe 18 connected to processing tank 17.

The desuperheating vessel 36 is conveniently provided with suitable liquid level sensing devices 55, 56 for determining the upper and lower limits of the level of liquid ammonia therein.

A valve 57 in the liquid ammonia supply line 58 from the high pressure supply vessel 29 is controlled by sensing devices 55, 56 to admit liquid ammonia into the desuperheating vessel as necessary to maintain the desired level within the vessel. may be done.

As will be appreciated, the fresh, relatively pure, anhydrous liquid ammonia placed from storage vessel 29 into desuperheating vessel 36 performs several functions.

First, the liquid may be directed to the desuperheating vessel 36 while still at a relatively high temperature, eg, about 95'F, and a relatively high pressure, about 180 psig.

Since the liquid in the desuperheating vessel is in equilibrium at a slight negative pressure and a temperature of about -28"F", some of the incoming fresh liquid ammonia is first vaporized and self-cooled to an equilibrium state.

In a conventional process, about 25% by weight of the liquid ammonia from the storage vessel is vaporized as a gas and the remaining 75% is allowed to self-cool to below -28°C.

In the method of the invention, significant benefits are achieved by self-cooling the reliquefied ammonia in the desuperheating stage, rather than in the process chamber 13, as would be the case if the reliquefied ammonia was led directly from the storage vessel 29 to the process chamber. is realized.

As will be recognized, the self-cooling action requires large amounts of ammonia), and such large amounts are not conventionally available in the process chamber 1.
If released within 3, this would increase the energy requirements of the heating section of the process chamber and thus the cooling requirements of the ammonia recovery system.

In operation of the system of FIG. 2, liquid ammonia containing a small amount of water is led into processing chamber 13 through pipes 52, 1B and immediately supplied to tank 11.

The fabric 10 is continuously advanced into and passed through the processing chamber at a predetermined speed.

When the fabric enters the chamber, it is immersed in the bath 17;
Saturated with liquid ammonia solution.

When the processing equipment is in steady state, the chamber 13 is completely saturated with ammonia vapor, so that when the fabric leaves the tank 17 and moves to its first point of contact with the drying equipment 21, it is saturated with liquid ammonia. remains saturated.

During this time, the main desired reaction between ammonia and the fabric takes place.

Shortly thereafter, the fabric undergoes an evaporation process to substantially terminate the reaction, and the remainder is substantially removed as the fabric passes over the drying device 21.22.

The ratio of processed fabric to ammonia solution utilized will vary widely depending on the type of fabric, but a ratio of 1 bond of liquid ammonia feed to 1 bond of fabric feed is not atypical and will be discussed here. Assume so for our purposes.

Therefore, for each bond of fabric entering the chamber, one bond of liquid ammonia solution is absorbed from the tank 17 and carried away with the moving fabric, approximately 95% of which is absorbed into the drying device 21.2.
evaporated by 2.

Therefore, for each bond of processed fabric, approximately one bond of consumed gas must be withdrawn from chamber 13.

Since the incoming fabric carries air trapped within its plow, and since that air inherently contains some moisture, the atmosphere within chamber 13 is necessarily somewhat dominated by air and its moisture. Recommended.

This occurs regardless of the efficiency of the inlet and outlet hole seals.

As this ammonia-rich gas mixture is withdrawn from the chamber and vented through desuperheating vessel 36, the moisture in the gas readily condenses in liquid ammonia 37 at about -28'F.

Furthermore, depending on the processing operation, the heat of the dryer 21,22 can also drive further moisture out of the fabric.

If not properly disposed of, these moistures will accumulate in the vessel 36 and gradually increase the temperature within the bath 31 until it no longer performs its intended function.

Therefore, such water must be extracted and discarded or used for lower grade applications.

However, in accordance with the present invention, the water-containing liquid ammonia in the desuperheating vessel 36 is constantly extracted through the tube 52 and utilized as a supplementary supply to the impregnation bath 11.

As a component of the present invention, provision is made conveniently and economically for the continuous removal of water from the process.

Although the particular technique used for water extraction is not critical to the basic method of the invention, it is important that some means be provided for water removal.

Most advantageously, and as one of the special aspects of the invention, there is provided a method for mechanically transporting the moisture, if practicable, together with the processed fabric and condensing the water portion from the hot effluent gas extracted from the processing chamber. Water is most conveniently removed by a combination of techniques, including methods of.

Therefore, if processing conditions permit, it is advantageous to adjust the time-temperature relationship of the heating section to primarily expel the ammonia portion while substantially retaining the water portion within the fabric.

By this means, the fabric leaves the process with slightly more moisture than when it entered the process, resulting in a net removal of moisture from the processing system.

Since not all textiles and not all processing conditions allow optimal adjustment of the heating section, the hot exhaust gas from the process is precooled and then cooled in order to condense at least a portion of the water portion from the consumed gas. Secondary arrangements are being made.

For example, the temperature of about -21" F, which is distantly related in non-contact heat exchangers of practical proportions by using liquid ammonia as the coolant, can be used to reserve the consumed gas to this temperature. By cooling, the water part becomes 2
It can be easily reduced to ~3%.

By providing for moisture removal by textile transport or by condensation from the heat effluent gas in this way, optimum process efficiency is achieved.

If the nature and special processing of the fabric permit, the heating step may be adjusted to completely drain the fabric of its own water.

However, if the process cannot be operated in this ideal manner, the resulting high 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 highly effective in eliminating undesirable amounts of water build-up within the system, while at the same time improving the system by utilizing a water-containing liquid ammonia solution in a desuperheating vessel for the supply of processing solutions. Significantly improves thermodynamic efficiency.

By refeeding this solution into the process, the water fraction naturally present in the recovered process gas is prevented from accumulating to undesirable levels and can be removed at an appropriate stage of the process. .

Under ideal conditions of process operation, the steady state moisture content within the desuperheating vessel can be kept at extremely low levels.

Even under adverse conditions, the water content of the desuperheating vessel is easily maintained at a level (2-3 degrees or less) that allows the main process steps themselves and the recovery system to operate at high efficiency levels.

One of the important additional advantages of this unique method is the improved thermodynamic efficiency resulting from feeding the reliquefied ammonia into the desuperheating vessel rather than directly into the processing chamber 13. .

The reliquefied ammonia in storage vessel 29 is therefore at high pressure and relatively high temperature.

In use, liquid ammonia must be brought to equilibrium at substantially atmospheric pressure (actually slightly below atmospheric pressure) and at an equilibrium temperature below -28.

In order to achieve this equilibrium, a large amount of reliquefied ammonia is vaporized as a gas.

When this occurs in a desuperheating vessel, the bulk of the vaporized gas is simply recycled through the recovery system, compressed, and reliquefied.

On the other hand, if the gas is evaporated in the processing chamber, as in conventional methods, the evaporated gas is returned to the recovery system only after being exposed to a large amount of heat within the processing chamber.

As will be appreciated, the heat attempting to raise the temperature of that portion of the vaporized gas solely to bring the liquid ammonia into equilibrium represents a consumption of thermal energy in the heating portion of the process.

Similarly, in order to reliquefy and recover this gas, heat must be removed from it.

This increases the operating load of the compressor.

Therefore, in this new method, by withdrawing the process feed from the desuperheating vessel and using the reliquefied ammonia as a supplementary supply to the vessel and not directly feeding it to the process chamber,
Not only is the water content of the system stabilized at a suitable equilibrium level, but significant energy efficiency is achieved.

The system of the present invention is extremely effective in removing unwanted water from recirculating ammonia systems.

This is of great importance in practical commercial systems.

For example, effective recycling techniques are important because there is an approximately 20:1 ratio between the amount of ammonia that is recycled and the amount that is essentially consumed in the process. .

Until now, such recycling techniques have been severely limited by the practical difficulties of removing the water that inevitably enters the system from the system.

The method and system of the present invention allows water to be removed in the early stages of the recovery process by direct contact with a mass of cold liquid ammonia, with or without an initial non-contact condensation step, to provide replenishment to the process. It operates on the basis of condensing parts.

The condensed water in the desuperheating vessel is thus directly re-supplied into the process as soon as it enters, allowing steady-state levels to be achieved.

Experience has shown that this level is low enough to have only a minor effect on processing reactions.

In this way, water of the order of 10% in the liquid ammonia solution substantially prevents the desired reaction, whereas the water fraction introduced into the processing fluid by the system of the present invention exhibits a relatively small increase in amount. Not too much.

In any case, preparations are made for pre-drying the incoming fabric.

This is not only to minimize the incoming moisture content, but also to allow the water portion to be removed by the fabric under certain conditions.

Therefore, in an ideal process, the fabric enters the process with a moisture content of about 5%, undergoes the desired liquid ammonia reaction, and leaves the process with a moisture content of, for example, about 5.1%.

By this means, the fabric itself serves as a means for continuous extraction of water from the ammonia recovery system, allowing the system to operate very efficiently and minimizing wastage or low-grade utilization of the recovered material.

If such ideal conditions cannot be achieved, other means are utilized to extract the water portion, such as non-catalytic condensation of the spent gas.

Of course, the form of the invention illustrated and stored herein is intended as representative only, and it is understood that certain changes may be made without departing from the express teachings of the specification. I want to be understood.

Accordingly, reference should be made to the appended claims in determining the full scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a simplified schematic representation of a typical configuration of a liquid ammonia textile processing system including an ammonia recovery system according to the present invention. FIG. 2 is a simplified schematic representation of the major components of an ammonia recovery and liquefaction system according to the present invention.

Claims (1)

Claims: 1. A moving cellulose-containing web material (10) is continuously exposed to liquid ammonia having a substantially low moisture content in a limited treatment zone (13) at a pressure substantially close to atmospheric pressure. 17) and then heating the web in the processing zone 21, 22) to evaporate the liquid ammonia from the web to remove mainly ammonia gas, air, and in a method for recovering and reusing gaseous effluents consisting of water vapor (
a) continuously withdrawing said gaseous effluent from said treatment zone (13); (b) continuously removing most, but not all, water vapor from said withdrawn gaseous effluent; 32a
), (c) a bath (37) of liquid ammonia with a substantially low moisture content, the gaseous effluent being maintained at approximately atmospheric pressure;
(d) thereafter compressing the ammonia gas (40); and condensing 43), (e) withdrawing liquid ammonia with a substantially low water content from the liquid ammonia bath (37) together with condensed water 52) for the treatment zone (17); (f) continuously replenishing said liquid ammonia bath (37) with water-free liquid ammonia (29) from said compression (42) and condensation (43) stages; (58) A method for recovering and reusing gas effluent, characterized by: 2 The water removal step (32a) comprises liquid ammonia (33
A method for recovering and reusing gaseous effluent according to claim 1, carried out by non-contact heat exchange with a, 34a). 3. Recovering and recycling the gaseous effluent according to claim 2, wherein the gaseous effluent is cooled by non-contact heat exchange with water (33, 34) prior to the condensation stage (33a, 34a). How to use. 4) Continuously exposing the moving cellulose-containing web material (10) to liquid ammonia with a substantially low water content at a pressure near atmospheric pressure in a confined treatment zone (13); 21. heating the web in the processing zone; ．． 22) A method for evaporating said liquid ammonia from said web and recovering and reusing the gaseous effluent consisting primarily of ammonia gas, air, and water vapor generated during continuous processing of said web,
(a) the web (10) is placed in the processing area (13);
(b) continuously withdrawing said gaseous effluent from said treatment zone (13) 27); (c) removing all of the gaseous effluent from said withdrawn gaseous effluent; 32a)
, (d) a bath (37) of liquid ammonia with a substantially low moisture content, wherein the gaseous effluent is maintained at about atmospheric pressure;
(e) compressing the ammonia gas after cooling the ammonia gas contained in the gaseous effluent and condensing water vapor from the ammonia gas; (e) compressing the ammonia gas; and condensing it 43), (f) drawing liquid ammonia with a substantially low water content from the liquid ammonia bath (37) together with the condensed water 52) for said treatment in 17). (g) continuously feeding said liquid ammonia bath (37) with water-free liquid ammonia (29) from said compression (42) and condensation (43) stages; Replenish (58)
, a method for recovering and reusing gaseous effluents. 5 The water removal step (32a) comprises liquid ammonia (33
A method for recovering and reusing gaseous effluent according to claim 4, carried out by non-contact heat exchange with a, 34a). 6. Recovering the gaseous effluent according to claim 5, wherein the gaseous effluent is cooled by non-contact heat exchange with water (33, 34) prior to the condensation stage (33a, 34a). How to reuse. 1) Continuously exposing a moving web material (10) to liquid ammonia having a substantially low moisture content in a defined treatment zone (13); 21° 22) to evaporate the liquid ammonia from the web and recover and reuse the effluent consisting primarily of ammonia gas, air, and water vapor generated during continuous processing of the web; (a) continuously withdrawing the effluent from the treatment zone (13); (b) converting a portion of the effluent into liquid ammonia (33a);
. (C) said precondensation continuously removes a portion of the condensed water vapor and ammonia from said effluent;
), (d) continuously introducing the remaining effluent not removed from said precondensation stage into a cooled first substantially water content liquid ammonia bath (37) maintained at atmospheric pressure; (e) the heat from said introduction step generates concomitant ammonia gas; (f) said compressing (40) and condensing (43) L the ammonia gas, including incidentals, to a second liquid ammonia holding bath (29) at a pressure above atmospheric; (g) said first liquid; Continuously withdraw liquid ammonia with a substantially low water content from the ammonia bath (37) together with condensed water 52), and transfer this withdrawn liquid to said treatment zone (13) for said exposure 17). 18), (h) continuously replenishing said first liquid ammonia bath (37) having a substantially low water content from said second liquid ammonia holding bath (29); Rikihiro is characterized by its ability to collect and reuse spilled materials. 8. A method according to claim 1, wherein the water content contained in the liquid ammonia of said first bath (37) is continuously maintained at a level between or below about 2 and 3%. How to collect and reuse spills. 9 The pre-condensation is carried out at -29,4'C(-
8. A method for recovering and reusing an effluent according to claim 7, wherein the effluent is cooled to 21' F. 10) Continuously exposing the moving web material (10) in a defined treatment zone (13) to liquid ammonia having a substantially low moisture content (17) and immediately thereafter exposing said web in said treatment zone. 21° 22) to evaporate the liquid ammonia from the web and recover and reuse the effluent consisting primarily of ammonia gas, air, and water vapor generated during continuous processing of the web; (a) continuously pre-drying said continuously moving web before entering said processing zone (13);
b) continuously withdrawing the effluent from the treatment zone (13) 27); (c) converting a portion of the effluent into liquid ammonia (33a);
. (d) said precondensation continuously removes a portion of the condensed water vapor and ammonia from said effluent;
a), (e) continuing the remaining effluent not removed from said pre-condensation stage into a cooled first substantially water content liquid ammonia bath (37) maintained at atmospheric pressure; (f) the heat from said introduction step generates concomitant ammonia gas; (g) said (h) compressing (40) and condensing (43) L, a second liquid ammonia reservoir at a pressure above atmospheric; continuously withdrawing liquid ammonia having a substantially low water content together with condensed water from a bath (37) of liquid ammonia in the bath (37), and transferring this withdrawn liquid to the treatment zone (13) for the exposure 17). 18), (i) continuously replenishing said first liquid ammonia bath (37) having a substantially low water content from said second liquid ammonia holding bath (29); A method for collecting and reusing spillage, characterized by: 11. Claim 10, wherein the water content contained in the liquid ammonia of said first bath (37) is continuously maintained at a level between or below about 2 and 3%.
Methods for recovering and reusing spills as described in Section 1. 12 The precondensation is carried out by precondensing the remainder of the effluent at -29,4'C(-
11. A method for recovering and reusing an effluent according to claim 10, wherein the effluent is cooled to 21' F. 13) continuously exposing the moving web material (10) in a treatment zone 03) to liquid ammonia with a substantially low moisture content 17), immediately thereafter heating said web in said treatment zone 21; 22) A method for evaporating said liquid ammonia from said web and recovering and reusing an effluent consisting primarily of ammonia gas, air, and water vapor generated during continuous processing of said web, comprising: ) continuously withdrawing said effluent from said treatment zone (13) 27); (b) in a cooled first substantially water content liquid ammonia bath (37) maintained at atmospheric pressure; continuously introducing said effluent to cool said ammonia gas and condense the contained water vapor; (c) heat from said introduction step generates concomitant ammonia gas; and (d) said The ammonia gas, including the incidental ammonia gas and the gases described in paragraph (g) below, is compressed (
40) and condensation (43) I in a second holding bath of liquid ammonia at a temperature above the equilibrium temperature of liquid ammonia at a pressure close to atmospheric pressure and at a pressure above atmospheric pressure. (29); (e) continuously withdrawing liquid ammonia having a substantially low water content together with the condensed water from said first liquid ammonia bath (37); (f) continuously discharging said first liquid ammonia bath (37) from said second liquid ammonia holding bath (29); (g) said replenishment step is characterized in that said replenishment step cools the newly added liquid ammonia gas to the equilibrium temperature of the first liquid ammonia (m37) while generating ammonia gas; A method for recovering and reusing.